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Control of vitamin C losses in vegetables prepared at a food service
Food Control 21 (2010) 264–271
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Control of vitamin C losses in vegetables prepared at a food service C.M.A. Rodrigues a,b, C.M. Della Lucia c,d, R.M.C. Azeredo c,d, A.M. Cota c,d, A.M.C. Santana c,d, H.M. Pinheiro-Sant’Ana c,d,* a
Centro Universitário do Espírito Santo – UNESC, Rua Fioravanti Rossi, 2930, Bairro Martinelli. CEP: 29.705-900, Colatina, ES, Brazil University Center of Espirito Santo – UNESC, Colatina, ES, Brazil c Departamento de Nutrição e Saúde, Universidade Federal de Viçosa, Avenida P.H. Rolfs, s/n, Campus Universitário. CEP: 36.570-000, Viçosa, MG, Brazil d Department of Nutrition and Health, Federal University of Viçosa, Viçosa, MG, Brazil b
a r t i c l e
i n f o
Article history: Received 14 May 2008 Received in revised form 19 May 2009 Accepted 26 May 2009
Keywords: Ascorbic acid Nutritional quality HACCP
a b s t r a c t This study aimed to elaborate a set of measures to control vitamin C losses in vegetables prepared at a food service (FS). Vegetables were randomly selected for vitamin C analysis by high performance liquid chromatography (HPLC) after delivery of raw material and during distribution for consumption of the food prepared. Some principles underlying the Hazards Analysis and Critical Control Points (HACCP) were applied to identify the Nutritional Control Points (NCP) for vitamin C losses. A Nutritional Control Measure (NCM) was adopted for each NCP as well as the monitoring criteria. The vegetables were again collected for vitamin C analysis after adoption of the NCMs. The results indicated reduction of vitamin C losses with NCM adoption. Ó 2009 Elsevier Ltd. All rights reserved.
1. Introduction Besides being economically important, the collective meal segment, represented by food service, plays an influential role in public health, as the meals it produces can affect the health and wellbeing of people (Badaró, 2007). The collective meal sector has significantly expanded in Brazil. It is estimated that one quarter of meals eaten by the population are consumed outside the house. According to the Brazilian Food Industry Association (ABIA), domestic food consumption accounted for annual earnings of around 65 billion dollars in the late 1990s, with 51 billion dollars being spent on food retail and 14 billion dollars on meals outside the house (almost 20% of the total), supplied by commercial establishments (restaurants, fast-food joints, diners, etc.) and collective meal service (public and private companies, hospitals, passenger catering, etc.) (Nutrição Brasil, 2002). Food safety has become increasingly important in the food market as a result of several structural changes in the food system. These changes include advances in public health sciences, changes in consumer knowledge on how to obtain and prepare food, and growth of the international market of food products (WHO, 2008). Thus, the market feels motivated to improve the quality of its products, making them attractive to the consumer from a
microbiological and nutritional viewpoint. This factor stimulates public intervention policies in the food market (Hartog, 2003). HACCP is the acronym for Hazard Analysis and Critical Control Points, a system that identifies and analyses hazards associated with the production of food and establishes ways to control them (Stringer, 1994). The HACCP system has been widely used for food sanitary–hygienic control. It is a proactive system of risk management designed to control hazards – by elimination or reduction of risks associated with identified hazards. The adoption of this system has proven to be effective in ensuring food innocuousness. The application of HACCP is compatible with the implementation of quality management systems, such as the ISO 9000 series, and is the system of choice in the management of food safety within such systems (FAO, 1997). Although it does not apply to nutritional safety (i.e., adequate amount and quality of nutrient supply), the system has a great potential to help reduce nutrient loss in collective meal services and to guarantee both their microbiological and nutritional quality (Badaró, 2007), as it acts as a safety assurance system. According to Barendz (1998), many hazards can compromise food safety, such as: microbiological (fecal coliform, Salmonella and Listeria); environmental (pesticide, heavy metal, nitrate); natural (ingredients); food additives and nutritional (fat consumption, obesity level). The application of HACCP principles consists of the following tasks as identified in the Logic Sequence for Application of HACCP (FAO, 1998):
* Corresponding author. Address: Departamento de Nutrição e Saúde, Universidade Federal de Viçosa, Avenida P.H. Rolfs, s/n, Campus Universitário, CEP: 36.570000, Viçosa, MG, Brazil. Tel.: +55 31 3899 3731; fax: +55 31 3899 2541. E-mail address: [email protected] (H.M. Pinheiro-Sant’Ana).
1. Assemble HACCP team. The food operation should assure that the appropriate product specific knowledge and expertise is available for the development of an effective HACCP plan.
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C.M.A. Rodrigues et al. / Food Control 21 (2010) 264–271
2. Describe product. A full description of the product should be drawn up, including relevant safety information. 3. Identify intended use. The intended use should be based on the expected uses of the product by the end consumer. 4. Construct flow diagram. The flow diagram should be constructed by the HACCP team. The flow diagram should cover all steps in the operation. 5. On-site confirmation of flow diagram. The HACCP team should confirm the processing operation against the flow diagram during all stages and hours of operation and amend the flow diagram where appropriate. 6. List all potential hazards associated with each step, conduct a hazard analysis, and consider any measures to control identified hazards. The HACCP team should list all of the hazards that may be reasonably expected to occur at each step from primary production until the point of consumption. 7. Determine Critical Control Points (CCP). The determination of a CCP in the HACCP system can be facilitated by the application of a decision tree, which indicates a logic reasoning approach. 8. Establish critical limits for each CCP. Critical limits must be specified and validated if possible for each Critical Control Point. Criteria often used include measurements of temperature, time, moisture level, available chlorine, and sensory parameters such as visual appearance and texture. 9. Establish a monitoring system for each CCP. The monitoring procedures must be able to detect loss of control at the CCP. 10. Establish corrective actions. The actions must ensure that the CCP has been brought under control. Deviation and product disposition procedures must be documented in the HACCP record keeping. 11. Establish verification procedures. Verification and auditing methods, procedures and tests, including random sampling and analysis, can be used to determine if the HACCP system is working correctly. 12. Establish documentation and record keeping. Efficient and accurate record keeping is essential to the application of a HACCP system. HACCP procedures should be documented. One of the factors determining the nutritional quality of nutrients is their vitamin content, due to its instability. Since the human body is not capable of synthesizing vitamins in sufficient amounts to satisfy its daily needs, diet should supply them. Vitamin losses may occur at the postharvest stage and during meal distribution to consumers. They can be caused by chemical changes that result in lower activity compounds, irreversible binding to other compounds in the food, or by degradation to inactive products. Oxygen, light and complexation with metal frequently play an important role in these losses (Ryley & Kajda, 1994). The recommendation to include vegetables in the diet is based on their low caloric value, high fiber content and significant levels of micronutrients, such as vitamin C (Giannakourou & Taoukis, 2003). However, vegetable shelf life (i.e. that length of time before vegetables are considered unsuitable for sale or consumption) is reduced and these nutrients are frequently exposed to conditions that degrade their quality, especially in terms of vitamins (Prodanov, Sierra, & Vidal-Valverde, 2003). Knowing the main factors affecting vitamin stability can prevent or reduce vitamin losses during food preparation. Consumers have become more aware of the nutritional quality of foods. Both consumers and food manufacturers have become particularly interested in vitamin C since it is one of the most sensitive (including fat-soluble and water-soluble vitamins) to processing and storage conditions, with its degradation being related to several factors, such as: oxygen, pH, light, temperature, and moisture content or water activity (Zanoni, Peri, Nani, & Lavelli,
265
1999; Rojas & Gerschenson, 2001). Vitamin C is frequently used as an indicator of severity of food processing: since it is well retained in foods, the retention percentage of all other vitamins (fat-soluble and water-soluble) should be similar or higher (Özkan, Kirca, & Cemeroglu, 2004). This is the first study, to our knowledge, that analyses vitamin C losses in a real situation and proposes measures to control these losses. Thus, we have opted to conduct a one-off experiment rather than use established data. It is expected that the adoption of control measures, compatible with the HACCP system will help reduce vitamin C losses in foods prepared at food service (FS), also leading to decreased loss of other nutrients. Thus, this study aimed to develop a set of measures that may contribute to improve the nutritional quality of meals at a FS, focusing on vitamin C loss minimization in vegetables. 2. Material and methods 2.1. Raw material The vegetables used in this study were routinely prepared at a FS, with six raw and two cooked preparations being selected and described as follows: – Raw preparations: lettuce (Lactuca sativa L.), carrot (Daucus carota L.), chicory (Cichorium endívia L.), cabbage (Brassica oleracea, var. acephala), white cabbage (Brassica oleracea, var. capitata) and tomato (Lycopersicom esculetum). – Cooked preparations: carrot (Daucus carota L.) and cauliflower (Brassica oleracea, var. botrytis L.). 2.2. Equipment and reagents The following equipments were utilized for vitamin extraction in the samples: microgrinder, model MA 102, Marconi; vacuum pump model CA Fanem; Excelsa Baby II centrifuge, model 206-R, Fanem. The mobile phase was degasified using a vaccum pump model CA Fanem. To measure the mobile phase pH a pHmetro UB-10, Hexis was used. Absorption spectra scanning and vitamin standard quantification were performed using a spectrophotometer UV 1601, Shimadzu. A forced-air circulation oven, model ETC 45 400ND series, Nova Ética, was used for total solids determination. A Sauter D-7470 analytical balance, with four decimal places was used to weigh the samples. The samples were prepared using analytical grade metaphosphoric acid (Merck, Germany), and ultrapure water Milli-QÒ type. High purity grade L-ascorbic acid (Vetec, Brazil) was used as vitamin standard. The following were used for mobile phase preparation: ultrapure water Milli-QÒ type, HPLC grade acetonitrile (Mallinckroat, USA); analytical grade metaphosphoric acid (Merck, Germany), and analytical grade tetrabutylammonium bromide (Vetec, Brazil). Filter paper number JP41 (J. Prolab, Brazil) and sterilized, disposable 4 mL syringes (Rymco, Colombia); HV Millex poliethylene filtration units, 0.45 lm porosity (Millipore, Brazil) were also used. 2.3. Methods 2.3.1. The FS selected and measures adopted A self-managed public FS participated in the study, with a popular standard menu and nutritionists and home economics specialists as part of its staff. This FS was chosen since it was the only self-managed public in town. Besides, its access was easy, because the FS is located at the University where this study was carried out. In 2000, it was renovated and new equipment and utensils were
– – Time control Time and volume of water control Time, temperature and water volume control NH, Nutritional Hazard; NCP, Nutritional Control Points; NCM, Nutritional Control Measures and NCC, Nutritional Control Criteria.
Cooking
Loss due to leaching and high temperature
Yes
Cooking after water starts to boil
– – 20 min before preparation and 1 h before distribution Immersion: volume of water sufficient to cover the vegetables for 10 min (150 ppm of chlorine) Time of cooking: 10 min at 100 °C. The volume of water must be sufficient to cover the vegetables Not applicable Not applicable Peeling close to preparation and distribution Reduction of volume of water and time of immersion No No Yes Yes exposure to heat oxidation exposure to air leaching to to to to Loss Loss Loss Loss Cooked carrot Transport Storage Peeling Hygienization/sanitization
due due due due
– Temperature control Time control Time and water volume control – – 20 min before preparation and 1 h before distribution Immersion: volume of water sufficient to cover the vegetables for 10 min (150 ppm of chlorine) Not applicable Not applicable Peeling close to preparation time Reduction of volume of water and time of immersion No No Yes Yes exposure to heat oxidation exposure to air leaching to to to to due due due due Loss Loss Loss Loss
Storage at room temperature (20–25 °C) for ±3 h Hygienization/sanitization
Raw grated Carrot Transport Storage Peeling Hygienization/sanitization
Time and water volume control Washing of the leaves by portion. Reduction of volume of water and time of immersion Yes
Immersion for 10 min (150 ppm of chlorine); volume of water sufficient to cover the leaves
Temperature control Storage at 15 °C Cold storage Yes
– – Not applicable No
Loss due to exposure to heat and sunlight Degradation due to heat and artificial light Loss through leaching, due to long contact with water
NCC NCM NCP NH Processing stage
2.3.2. Preparation and sample collection In the first phase of the study, the vegetables were prepared according to the establishment’s production routine. Vitamin C content of each vegetable was analyzed before and after preparation, making it possible to analyze the vitamin content under normal preparation and consumption conditions. Samples were collected randomly from different parts of the gastronorms (GN), during vegetable delivery and the end of the period of meal distribution (vegetables were collected only once after 90 min of exposure, simulating the mean exposure time used by the FS). On average, 50 g of each vegetable were collected on three different days, characterizing three repetitions. After collection, the samples were packed in plastic bags, placed in Styrofoam boxes and taken to the Vitamin Analysis Laboratory of the Department of Nutrition and Health of the Federal University of Viçosa. The vegetables were then stored in the refrigerator, at approximately 5 °C, until vitamin extraction after a maximum of 24 h. The chromatographic analyses were performed immediately after extraction. In the second phase of the study, the proposed NCMs for vegetable preparation were adopted. New vegetable samples were collected (three repetitions) and new vitamin C content analyses were performed to verify whether the NCMs were efficient in preserving the vitamin.
Lettuce, chicory and collard Transport
acquired, making it possible to implement the Good Manufacturing Practices (GMPs); in 2004, training was provided to its employees. The implementation of the GMPs allowed the application of the HACCP practice guidelines. WHO defines GMPs as ‘‘that part of quality assurance which ensures that products are consistently produced and controlled to the quality standards appropriate to their intended use and as required by the marketing authorization” (WHO, 1992). GMPs cover all aspects of the manufacturing process: defined manufacturing process; validated critical manufacturing steps; suitable premises, storage, transport; qualified and trained production and quality control personnel; adequate laboratory facilities; approved written procedures and instructions; records to show all steps of defined procedures taken; full traceability of a product through batch processing records and distribution records; and systems for recall and investigation of complaints (WHO, 1997). At the FS, groceries are purchased weekly from a fruit and vegetable producer, except for the leafy vegetables, which are purchased according to the menu needs. The leafy vegetables are supplied by a local farmer, and the others by the Minas Gerais Supply Center (CEASA, MG). Based on the HACCP system principles cited by Almeida (1998) and NACMCF (1998), the following steps were implemented by the participating FS: description of the operational procedures using flow charts of each vegetable selected, including analysis of the following stages: vegetable reception, storage, preparation and distribution; identification of the stages where significant Nutritional Hazards-NH (possible nutrient loss in food due to the adoption of inappropriate techniques and procedures) might occur; identification of Nutritional Control Points-NCP (points that must be corrected to minimize nutrient losses in foods); proposition of Nutritional Control Measures – NCM (procedures adopted to prevent or reduce losses that compromise the nutritional quality of food, maintaining the nutritional risk under control); definition of Nutritional Control Criteria – NCC (procedure adopted for each Nutritional Control Measure-NCM coupled to a Nutritional Control Point – NCP; it is a minimum or maximum of a parameter to be adopted in respect of NCP in order to prevent, eliminate or reduce the risk of loss of nutrients in foods), based on specialized literature, including the following factors: storage and cooking time and temperature, water/food relation, presence of light and oxygen; and definition of monitoring procedures.
Monitoring
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Table 1 Description of the NH associated to vitamin C losses, NCP, NCM, NCC and monitoring procedures in the handling stages of lettuce, chicory, collard, raw carrot and cooked carrot prepared at the food service.
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C.M.A. Rodrigues et al. / Food Control 21 (2010) 264–271 Table 2 Description of the NH associated to vitamin C losses, NCP, NCM, NCC and monitoring procedures in the handle stages of cooked cauliflower, white cabbage and tomato. Processing stage
NH
NCP
NCM
NCC
Monitoring
Transport Storage Slicing
Loss due to exposure to heat Loss due to oxidation Loss due to exposure to air
No No Yes
Loss due to leaching
Yes
Cooking
Loss due to leaching and inadequate temperature
Yes
Cooking after water starts to boil
– – 20 min before preparation and 1 h before distribution Immersion: volume of water sufficient to cover vegetables for 10 min (150 ppm of chlorine) Time of cooking: 10 min at 100 °C. The volume of water must be sufficient to cover the vegetables
– – Time control
Hygienization/ sanitization
Not applicable Not applicable Slicing close to time of distribution Reduction of volume of water and time of immersion
White cabbage
Transport Storage Hygienization/ sanitization
Loss due to exposure to heat Loss due to oxidation Loss due to leaching
No No Yes
Not applicable Not applicable Reduction of volume of water and time of immersion
– – Immersion: volume of water sufficient to cover vegetables for 10 min (150 ppm of chlorine)
– – Time and volume of water control
Tomato
Transport Storage Hygienization/ sanitization
Loss due to exposure to heat Loss due to oxidation Loss due to leaching
No No Yes
Not applicable Not applicable Reduction of volume of water and time of immersion
– – Immersion: volume of water sufficient to cover the vegetables for 10 min (150 ppm of chloride)
– – Time and volume of water control
Cooked cauliflower
Time and volume of water control
Time, temperature and volume of water control
NH, Nutritional Hazard; NCP, Nutritional Control Points; NCM, Nutritional Control Measures and NCC, Nutritional Control Criteria.
2.3.3. Vitamin C extraction and analyses The analyses were carried out in the dark, with care being taken to protect the pigments from light and oxygen, using aluminum foil to cover the glassware, amber flasks and ‘‘black-out” blinds. The conditions for vitamin C extraction and analyses were based on a method proposed by Giannakourou and Taoukis (2003), with some modifications: 5 g of each sample were weighed; 15 mL of 4.5% metaphosphoric acid were added to the sample, which was ground in a microgrinder. The material was then vacuum-filtered through a Büchner funnel using filter paper, and diluted to 25 mL volume with ultra pure water using a volumetric flask. The sample was centrifuged at a speed of 4000 rpm during 15 min and placed in the refrigerator (5 °C) until analysis by High Performance Liquid Chromatography (HPLC). Before injection, the material was again filtered through filtering units. The chromatographic conditions were: high performance liquid chromatograph, Shimadzu, with high pressure pump, model LC-10AT VP; automatic injector with 50 lL loop, model SIL-10AF; UV-Visible, diode array detector, model SPD-M10A; Multi System software model Class VP 6.12, controls up to four systems; Microsorb column RP-18 5, 250 mm in length and 4 mm internal diameter; mobile phase composed of 80% ultra pure water (pH adjusted for 2.2 with metaphosphoric acid), 20% acetonitrile, 10 mM tetrabutylammonium bromide; 1 mL/min flow; run time between 10–15 min for samples and 5 min for standards. The chromatograms were monitored at 238 nm. Analyses were controlled by Multi System software model Class VP 6.1. 2.3.4. Vitamin C standard-curve, identification and quantification After quantification in a spectrophotometer, 5 and 15 lL of AA 1 mg/mL solution and 15 and 30 lL of 4 lL/mL solution were injected to build the standard-curve. Vitamin identification in the vegetable samples was carried out by comparing standard and sample retention times under the same conditions. The spectra of the standard absorption and peaks of interest in the samples were also compared, using the diode array detector.
Vitamin C concentration in the samples was calculated based on the standard-curve and regression equation obtained. The real concentration value in the samples was obtained by calculating the dilutions performed. 2.3.5. Linearity range determination Linearity range was tested under the chromatographic conditions optimized in this study. Injections of increasing volumes (5–50 lL) of the standard solution were performed in triplicate. Linearity was determined based on the results obtained for the peak areas and their respective concentrations, through a linear regression analysis. Linearity was evaluated using the correlation coefficient (R2) obtained (Albalá-Hurtado, Novella-Rodríguez, Veciana-Nogués, & Mariné-Font, 1997). 2.3.6. Vitamin standard recovery analysis Using the extraction procedures and chromatographic conditions optimized in this study, recovery tests were conducted by adding known concentrations of the vitamin C standard into samples of cooked carrot cooked cauliflower, cabbage and raw tomato. To evaluate and determine recovery, the samples were carefully homogenized and weighed in two tubes, to obtain two similar aliquots. The standard solution was added to one of the samples in sufficient concentration to represent 50% of the original vitamin content of each vegetable tested, with the other tube being used as control. Two tubes of each sample were submitted to extraction and analysis procedures. All procedures were carried out in duplicate and the samples were also injected in duplicate. The recovery values were obtained based on the percent difference between the analyzed and added contents. Percent recovery values (%R) were obtained through the following equation:
%R ¼ ðFinal compound content Amount of added compoundÞ =ðInitial amountÞ 100
ð1Þ
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2.3.7. Total solids determination Moisture content of the samples was determined according to the method described by Kawashima and Soares (2003) for green leafy vegetables by applying the time and temperature binome (105 °C/2 h) according to Guinazi (2004). Moisture content was obtained after drying the samples in a forced-air circulation oven followed by chilling in a desiccator (2 h min) and weighing. The following equation was used to calculate moisture content in the samples: Moisture content (%) = (wet weight dry weight)/ wet weight 100. Total solids content was determined by the difference between total sample and moisture contents.
min loss. One of the most important points was lack of temperature and cooking time monitoring as well as immersion time and water volume. The FS routinely sanitizes the vegetables, except for cabbage and cooked carrots, which are just washed under tap water. Carrots and cauliflower were placed in the cooking pot before the water boiled, increasing the chances of losses due to heat and leaching. This behavior was probably due to lack of knowledge or training of the workers. After preparation, the vegetables were stored in a refrigerated pass through (5–8 °C) before distribution, a positive measure to maintain their microbiological and nutritional quality.
3. Results and discussion 3.1. Vitamin C loss stages and definition of control measures
3.2. Vitamin C qualitative analysis, linearity range, and vitamin standard recovery
After analysis of the operational procedures, the manipulation procedure stages, where significant hazards for vitamin C losses might occur, were identified. The NCMs and their respective monitoring formats were associated to these hazards, aimed at controlling vitamin losses in the vegetables (Tables 1 and 2). The NCMs were experimentally adopted at the FS to control vitamin C losses in the samples, after their implementation. It was observed that following delivery, the leafy vegetables were exposed for a prolonged period of time (±3 h) at room temperature (20–27 °C) until sanitized. One of the adopted NCMs was to store the leafy vegetables under refrigeration (10 °C) until sanitization. Following the FS routine, the remaining vegetables were also stored in the refrigerator (8–10 °C), thus reducing vita-
Fig. 1 shows typical chromatographic profiles of two of the samples analyzed in this study. The extraction technique resulted in samples with reduced amounts of interfering compounds, making it easier to separate the compounds of interest. The chromatographic conditions used allowed a good ascorbic acid resolution, which ensured safe vitamin quantification in the samples. The diode array detector provided important spectral information for ascorbic acid identification in the samples. Fig. 2 shows an example of overlapping between the vitamin standard absorption spectra and the peak of interest in a raw collard sample. The linearity range obtained for AA was wide (12.3–80.5 mg), allowing the collection of reliable data in the studied ranges. The correlation coefficient (R2) was equal to 0.977.
AA
Absorvance (mAU)
1400 1200 1000 800 600 400 200 0 0
2
4
6
8
10
12
14
12
14
Retention Time (min) 600
Absorvance (mAU)
500 400 300 AA 200 100 0 0
2
4
6
8
10
Retention Time (min) Fig. 1. Analysis by HPLC of ascorbic acid (AA) raw collard (A) and lettuce (B). Chromatographic conditions: Mobile phase: 80% of ultrapure water (pH adjusted to 2.2 with metaphosphoric acid) + 20% of acetonitrile; + 10 mM of bromide tetrabutylammonium; Microsorb RP-18 column; diode array detector (detection at 238 nm). Flow: 1 mL/min; injection volume: 30 lL.
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500
Raw Collard sample
Absorbance (mAU)
Standard 2.92 min
400 300 200 100 0 200
220
240
260
280
300
320
340
360
Wavelength (nm) Fig. 2. Absorption spectra overlap of AA standard of raw collard analysed by the diode array detector.
AA recovery percentage in the four vegetables ranged between 69.24% and 93.35%. Recovery percentage was lower in cooked cauliflower samples. A broader exposure of the chopped vegetable might have influenced this low recovery rate. The cauliflower tissue becomes very soft after cooking and sectioning into small pieces (to make grinding easier) might have increased the surface in contact with air, leading to partial degradation of the vitamin. Rizzolo, Brambilla, Valsecchi, and Eccher-Zerbini (2002) found similar results in AA recovery rates in pears (between 60% and 85%). The authors reported that AA recovery is significantly affected by small temperature variations and exposure to light during extraction. 3.3. Ascorbic acid content in vegetables AA contents in the studied vegetables, in natura and after routine preparation at the institutional restaurant, are shown in Table 3. AA content varied greatly among the studied vegetables, but, in general, the values were compatible with those presented by the American Guide of Food Composition (USDA, 2008). It should be noted that this table reflects nutrient contents in vegetables cultivated in the United States. In addition, vegetable variety, mode of cultivation, and soil type can influence nutrient content in foods (Campos, 2006). Some authors found similar AA values for cauliflower, cabbage and tomato (Lee & Kader, 2000). Gökmen, Kahraman, Ddemir, and Acar (2000) found lower values for tomato and cabbage (7.9 and 5.5 mg/100 g, respectively). Della Lucia, Campos, Tomazini, and Pinheiro-Sant’Ana (2006) found AA contents ranging between 11.66 and 16.20 mg/100 g after standard processing conditions. Few studies are found in the literature associating vitamin C content in lettuce, carrot, chicory, collard, cauliflower, cabbage,
and tomato and on the effect preparation and cooking methods can have on their stability. However, Della Lucia et al. (2006) found contents of 88.27 and 99.71 mg/100 g in stir-fried collard, which are higher than those found in this study, since stir-fried vegetables concentrate nutrients by weight units. Considering the expression of AA contents on a dry basis, the vegetables showing the highest vitamin content reduction were chicory and lettuce. Collard, however, had a smaller loss. Type of slicing is one of the factors that might have contributed to the percent difference between these two vegetables. Collard is sliced using a mechanic slicer, while chicory is manually sliced using a knife. Lettuce leaf is more sensitive to transportation and storage damages (Marques, Baldotto, Santos, & Oliveira, 2003) and even to type of cutting, while collards and chicory leaves are more resistant. Among the cooked vegetables, cauliflower presented a higher AA loss percentage. Grated raw carrot presented a smaller loss than cooked carrot, as expected. Tomato and cabbage presented the lowest AA losses. After analysis of AA content in the vegetables under real preparation conditions, the NCMs proposed were duly monitored to verify their efficiency in retaining vitamin in the foods being tested. AA contents in vegetables in natura and after preparation, adopting the NCMs, are show in Table 4. Fig. 3 shows AA retention percentage in the vegetables analyzed at the FS, before and after adoption of the NCMs. Overall, the vegetables showed higher vitamin retention after NCM adoption. Losses were reduced in approximately 88%, 49% and 45% for collard, lettuce and chicory, respectively, and approximately 30% for cauliflower. Although loss percentage increased in cabbage, it should be emphasized that this vegetable was duly sanitized, a procedure not previously conducted.
Table 3 Ascorbic acid in vegetables in natura and after preparation at food service, before the adoption of the Nutritional Control Measures (NCMs). Vegetable
Lettuce Cooked carrot Raw grated carrot Chicory Collard Cooked cauliflower White cabbage Tomato *
In natura
After preparation
Wet base* (mg/100 g)
Dry base* (mg/100 g)
Wet base* (mg/100 g)
Dry base* (mg/100 g)
Losses in dry base (%)
9.2(3.1–18.4) 8.4(5.5–11.1) 10.1(9.3-10.7) 15.7(5.7–24.6) 98.9(94.4–104) 52.7(42.0–61.6) 33.9(21.6–40.4) 15.9(14.7–16.2)
235(92.7–428) 84.5(65.1–105) 107(94.5–126) 228(74.0–325) 812(708–922) 570(465–741) 545(401–716) 294(278–305)
5.8(3.8–7.6) 6.7(5.4–8.1) 7.5(5.5–8.5) 4.5(2.5–6.1) 61.1(50.1–71.9) 10.9(8.3–16.1) 31.1(20.9–38.4) 13.3(10.1–15.6)
126(47.4–171) 51.6(45.5–63.4) 74.2(60.5–81.0) 72.5(45.8–88.0) 577(572–581) 156(111–238) 482(382–593) 229(164–292)
46.5 38.9 30.8 68.2 28.9 72.6 11.6 22.2
Means of three repetitions (range).
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Table 4 Ascorbic acid in vegetables in natura and after preparation at food service, after the adoption of the Nutritional Control Measures (NCMs). Vegetable
In natura
After preparation *
Lettuce Cooked Carrot Grated raw carrot Chicory Collard Cooked cauliflower White cabbage Tomato *
*
Wet basis (mg/100 g)
Dry basis (mg/100 g)
Wet basis* (mg/100 g)
Dry basis* (mg/100 g)
Losses in dry basis (%)
8.1(6.1–10.9) 7.8(6.6–9.3) 6.9(6.5–7.3) 8.7(6.9–10.3) 95.3(90.2–105) 49.9(48.4–50.7) 29.4(22.2–38.1) 19.9(15.6–24.6)
193(153–272) 71.5(63.4–83.6) 69.1(63.4–72.6) 134(113–157) 812(723–892) 748(496–875) 438(336–605) 348(268–460)
5.4(4.1–7.5) 6.3(5.6–6.6) 6.7(6.5–7.1) 3.9(3.1–4.1) 84.7(73.1–99.8) 21.2(20.0–23.4) 26.6(21.4–35.4) 14.5(12.4–15.6)
147(90.2–229) 58.4(48.4–63.4) 60.9(59.1–63.4) 84.1(52.2–109) 784(599–950) 374(339–405) 392(285–553) 260(194–299)
23.7 18.4 8.4 37.5 3.4 50.1 10.6 25.2
Means of three repetitions (range).
120 96.6
AA Retention (%)
100
60
81.6
76.3
80 53.5
61.1
88.4 89.4
87.6
77.8 74.8
71.1
69.1
62.5 49.9
40
31.8
27.4
20 0
Lettuce
Cooked Raw Grated Carrot Carrot
Chicory
Before adoption of NCM
Collard
Cooked White Cauliflower Cabbage
Tomato
After adoption of NCM
Fig. 3. AA retention in vegetables prepared in food service, before and after the adoption of the Nutritional Control Measures.
AA retention was similar for tomato and cabbage before and after NCM adoption. It is worth mentioning that these vegetables presented smaller AA loss percentages from reception to distribution. However, in a study by Campos (2006), storage under refrigeration favored AA retention in tomatoes, with mean retention of 89% under 10 °C and 81% under room temperature (24 °C mean). The higher vitamin C retention in cooked vegetables confirms the efficiency of the NCMs regarding water volume, cooking time and allowing the water to boil before beginning cooking. Vitamin C loss reduction in most of the vegetables analyzed was also a result of reduced preparation time. Before NCM adoption, the vegetables would be ready for consumption within, approximately, 3 h before distribution. After the measures were adopted, this time was reduced to approximately 1 h. No studies were found in the literature linking the use of the HACCP system and vitamin loss control in vegetables. However, in a study conducted by Fernandes, Dutra, and Proença (2007), the Nutritional and Sensorial Quality Evaluation System (NSQE) was applied in combination with the HACCP system. This study evaluates the nutritional and sensorial criteria applied to black and red beans prepared at a FS. The findings point to the need to soak the grains to minimize their antinutritional factors, improving their sensorial quality, as shown by a higher acceptance by tasters, and, though not measured, increased grain digestibility. Although the analysis of nutrients, especially vitamins, was not conducted in this study, the NSQE system may be considered a helpful tool in maintaining nutritional characteristics. In a FS case study aimed to implement the HACCP system principles in meat preparation, Hering, Proença, Sousa, and Veiros (2006) concluded that possible corrective actions could be associ-
ated not only with hygienic–sanitary control, but also with improved nutritional and sensorial quality of the preparations. Although vitamin content determination was not conducted in this study, it must be emphasized that the nutritional value of meat might be compromised during pre-preparation (freezing, thawing, and cutting) and preparation (cooking),with meats losing expressive amounts of liquid, resulting in water-soluble nutrient losses (Pires, Rosado, Azevedo, Neves, & Miranda, 2002). Thus, determination of nutritional control measures can be useful under this aspect. Soriano, Moltó, and Mañes (2002) suggested the incorporation of a nutritional concept into the HACCP methodology. These authors argued that this initiative would eventually improve the quality of life of FS users. Our study showed that some procedures can be adopted to prevent vitamin C losses in vegetables prepared at FS, such as: short storage periods; vegetable storage under refrigeration; slicing vegetables close to serving time and in larger pieces to reduce exposure to oxygen. Also, vegetable hygienization and sanitation should be efficient enough to eliminate dirt and contamination. However, time should be monitored to avoid excessive contact with water and leaching losses. It is important to take into account that safety of raw vegetables is a major issue and should not be compromised in the name of vitamin C losses control. This stage should, whenever possible, precede the slicing stage, since it causes a higher contact with water, increasing not only water-soluble vitamin losses, but also the loss of other micronutrients, such as minerals, and of water-soluble components, such as pigments, sugars and starch, responsible for the sensorial quality of these products. Cooking water should be in a sufficient amount to cover
C.M.A. Rodrigues et al. / Food Control 21 (2010) 264–271
the vegetables, and the cooking methods, whenever possible, should be steam cooking, pressure cooking or stir-frying in oil, to avoid direct contact of the nutrients with water. When not possible (as in this study, there was no food steamer available), cooking water should be used in the preparation of soups and sauces to use the water-soluble vitamins lost through leaching. Vegetable cooking time and temperature should be monitored. Meal distribution should occur 1 hour after preparation at most, provided vegetables are kept under refrigeration. 4. Conclusions Assuming that vitamin C losses are indicators of loss of other vitamins, the NCMs can be effective in minimizing vitamin losses in vegetables prepared at FSs. This study concluded that the NCMs are effective in reducing vitamin C losses in vegetables. The Good Manufacturing Practices utilized throughout the development of this study comprise a larger concept, involving not only widely disseminated hygienic-sanitary control but also aspects related to preservation of the nutritional value of the vegetables. In this study, we have shown that some procedures can be adopted to prevent vitamin C losses in vegetables prepared at FSs, such as: shorter storage periods; vegetable storage under refrigeration; slicing vegetables close to serving time and in larger pieces, adequate hygienization, controlling cooking time and temperature and shorter time between preparation and meal distribution. Through the determination of NCPs and the establishment of corrective actions, it was possible to obtain vegetables with higher nutritional quality. This study can be considered the starting point for further research adopting some HACCP system principles to control the nutritional quality of meals prepared at FSs, as studies of this nature are practically nonexistent internationally. We suggest the implementation of other studies to assess the losses of vitamin C in each stage of the handling of vegetables, so that control measures can be implemented in a more punctual way. The results obtained in this study on the vitamin C content in the vegetables analyzed can contribute to their nutritional characterization, as similar studies are not available in Brazil. Acknowledgement The authors thank PIBIC/CNPq and CAPES for the financial support. References Albalá-Hurtado, S., Novella-Rodríguez, S., Veciana-Nogués, M. T., & Mariné-Font, A. (1997). Determination of vitamins A and E in infant milk formulae by highperformance liquid chromatography. Journal of Chromatography A, 778, 243–246. Almeida, C. R. (1998). O sistema HACCP como instrumento para garantir a inocuidade dos alimentos. Higiene Alimentar, 12(53), 12–20. Badaró, A. C. L. (2007). Avaliação do nível de adoção das boas práticas de manipulação de alimentos em restaurantes do município de Ipatinga, Minas Gerais (75 p). Dissertation (Master’s in Nutrition Science). Federal University of Viçosa. (accessed 15.04.09). Barendz, A. W. (1998). Food safety and total quality management. Food Control, 9(2– 3), 163–170. Campos, F. M. (2006). Avaliação de práticas de manipulação de hortaliças visando a preservação de vitamina C e carotenóides (92 p). Dissertation (Master’s in Nutrition Science). Federal University of Viçosa.
271
Della Lucia, C. M., Campos, F. M., Tomazini, A. P. B. & Pinheiro-Sant’Ana, H. M. (2006). Validação de critérios para controle de perdas de vitamina C em hortaliças preparadas em unidade hospitalar. In Anais do XIX Congresso Brasileiro de Nutrição, São Paulo. FAO Food and Agriculture Organization. (1997). Hazard analysis and critical control point (HACCP) system and guidelines for its application. (accessed 01.04.09). Fernandes, A. C., Dutra, B. E. & Proença, R. P. C. (2007) Critérios de qualidade nutricional e sensorial de preparações de feijão preto e vermelho. Revista Nutrição em Pauta. (accessed 15.04.09). Giannakourou, M. C., & Taoukis, P. S. (2003). Kinetic modeling of vitamin C loss in frozen green vegetables under variable storage conditions. Food Chemistry, 83, 33–41. Gökmen, V., Kahraman, N., Ddemir, N., & Acar, J. (2000). Enzymatically validated liquid chromatographic method for the determination of ascorbic and dehydroascorbic acids in fruit and vegetables. Journal of Chromatography A, 881, 309–316. Guinazi, M. (2004). Tocoferóis e tocotrienóis em hortaliças, ovos e óleos vegetais utilizados em restaurantes comerciais (90 p). Dissertation (Master in Nutrition Science). Federal University of Viçosa. Hartog, J. D. (2003). Feed for food: HACCP in the animal feed industry. Food Control, 14, 95–99. Hering, B., Proença, R. P. C., Sousa, A. A., & Veiros, M. B. (2006). Evaluation of nutritional and sensorial quality in meal production – NSQE system. Journal of Foodservice, 17(4), 173–181. Kawashima, L. M., & Soares, L. M. V. (2003). Mineral profile of raw and cooked leafy vegetables consumed in Southern Brazil. Journal of Food Composition and Analysis, 16, 605–611. Lee, S. K., & Kader, A. A. (2000). Preharvest and postharvest factors influencing vitamin C content of horticultural crops. Postharvest Biology and Technology, 20, 207–220. Marques, P. A. A., Baldotto, P. V., Santos, A. C. P., & Oliveira, L. (2003). Qualidade de mudas de alface formadas em bandejas de isopor com diferentes números de células. Horticultura Brasileira, 21(4), 649–651. NACMCF – National Advisory Committee on Microbiological Criteria for Foods (1998). Hazard analysis and critical control point principles and application guidelines. Journal of Food Protection, 61(9), 1246–1259. Nutrição Brasil (2002). Como funciona o setor de alimentação coletiva no Brasil. May/ June. Özkan, M., Kirca, A., & Cemeroglu, B. (2004). Effects of hydrogen peroxide on the stability of ascorbic acid during storage in various fruit juices. Food Chemistry, 88, 591–597. Pires, I. S. C., Rosado, G. P., Azevedo, R. M. C., Neves, M. B., & Miranda, L. S. (2002). Composição centesimal, perdas de peso e maciez de lombo (Logissimus dorsi) suíno submetido a diferentes tratamentos de congelamento e descongelamento. Revista Nutrição, 15(2), 162–166. Prodanov, M., Sierra, I., & Vidal-Valverde, C. (2003). Influence of soaking and cooking on the tiamin, riboflavin and niacin contents of legumes. Food Chemistry, 84, 271–277. Rizzolo, A., Brambilla, A., Valsecchi, S., & Eccher-Zerbini, P. (2002). Evaluation of sampling and extraction procedures for the analysis of ascorbic acid from pear fruit tissue. Food Chemistry, 77, 257–262. Rojas, A. M., & Gerschenson, L. N. (2001). Ascorbic acid destruction in aqueous model systems: An additional discussion. Journal of the Science of Food and Agriculture, 81, 1433–1439. Ryley, J. R., & Kajda, P. (1994). Vitamins in thermal processing. Chemistry, 49, 119–129. Soriano, J. M., Moltó, J. C., & Mañes, J. (2002). Development of a nutritional HACCP plan. Journal of the American Dietetic Association, 102(10), 1399–1401. Stringer, M. F. (1994). Safety and quality management through HACCP and ISO 9000. Dairy, Food and Environmental Sanitation, 14(8), 475–481. USDA United States Department of Agriculture (2008). USDA National Nutrient Database for standard reference. (accessed23.02.08). WHO World Health Organization (1992). Expert Committee on Specifications for Pharmaceutical Preparations. Good Manufacturing Practices for Pharmaceutical Products. Technical Report Series n. 823. WHO World Health Organization (1997). A WHO guide for good manufacturing practices (GMP) requirements. (accessed 02.04.09). WHO World Health Organization (2008). Food Safety.
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Control of vitamin C losses in vegetables prepared at a food service C.M.A. Rodrigues a,b, C.M. Della Lucia c,d, R.M.C. Azeredo c,d, A.M. Cota c,d, A.M.C. Santana c,d, H.M. Pinheiro-Sant’Ana c,d,* a
Centro Universitário do Espírito Santo – UNESC, Rua Fioravanti Rossi, 2930, Bairro Martinelli. CEP: 29.705-900, Colatina, ES, Brazil University Center of Espirito Santo – UNESC, Colatina, ES, Brazil c Departamento de Nutrição e Saúde, Universidade Federal de Viçosa, Avenida P.H. Rolfs, s/n, Campus Universitário. CEP: 36.570-000, Viçosa, MG, Brazil d Department of Nutrition and Health, Federal University of Viçosa, Viçosa, MG, Brazil b
a r t i c l e
i n f o
Article history: Received 14 May 2008 Received in revised form 19 May 2009 Accepted 26 May 2009
Keywords: Ascorbic acid Nutritional quality HACCP
a b s t r a c t This study aimed to elaborate a set of measures to control vitamin C losses in vegetables prepared at a food service (FS). Vegetables were randomly selected for vitamin C analysis by high performance liquid chromatography (HPLC) after delivery of raw material and during distribution for consumption of the food prepared. Some principles underlying the Hazards Analysis and Critical Control Points (HACCP) were applied to identify the Nutritional Control Points (NCP) for vitamin C losses. A Nutritional Control Measure (NCM) was adopted for each NCP as well as the monitoring criteria. The vegetables were again collected for vitamin C analysis after adoption of the NCMs. The results indicated reduction of vitamin C losses with NCM adoption. Ó 2009 Elsevier Ltd. All rights reserved.
1. Introduction Besides being economically important, the collective meal segment, represented by food service, plays an influential role in public health, as the meals it produces can affect the health and wellbeing of people (Badaró, 2007). The collective meal sector has significantly expanded in Brazil. It is estimated that one quarter of meals eaten by the population are consumed outside the house. According to the Brazilian Food Industry Association (ABIA), domestic food consumption accounted for annual earnings of around 65 billion dollars in the late 1990s, with 51 billion dollars being spent on food retail and 14 billion dollars on meals outside the house (almost 20% of the total), supplied by commercial establishments (restaurants, fast-food joints, diners, etc.) and collective meal service (public and private companies, hospitals, passenger catering, etc.) (Nutrição Brasil, 2002). Food safety has become increasingly important in the food market as a result of several structural changes in the food system. These changes include advances in public health sciences, changes in consumer knowledge on how to obtain and prepare food, and growth of the international market of food products (WHO, 2008). Thus, the market feels motivated to improve the quality of its products, making them attractive to the consumer from a
microbiological and nutritional viewpoint. This factor stimulates public intervention policies in the food market (Hartog, 2003). HACCP is the acronym for Hazard Analysis and Critical Control Points, a system that identifies and analyses hazards associated with the production of food and establishes ways to control them (Stringer, 1994). The HACCP system has been widely used for food sanitary–hygienic control. It is a proactive system of risk management designed to control hazards – by elimination or reduction of risks associated with identified hazards. The adoption of this system has proven to be effective in ensuring food innocuousness. The application of HACCP is compatible with the implementation of quality management systems, such as the ISO 9000 series, and is the system of choice in the management of food safety within such systems (FAO, 1997). Although it does not apply to nutritional safety (i.e., adequate amount and quality of nutrient supply), the system has a great potential to help reduce nutrient loss in collective meal services and to guarantee both their microbiological and nutritional quality (Badaró, 2007), as it acts as a safety assurance system. According to Barendz (1998), many hazards can compromise food safety, such as: microbiological (fecal coliform, Salmonella and Listeria); environmental (pesticide, heavy metal, nitrate); natural (ingredients); food additives and nutritional (fat consumption, obesity level). The application of HACCP principles consists of the following tasks as identified in the Logic Sequence for Application of HACCP (FAO, 1998):
* Corresponding author. Address: Departamento de Nutrição e Saúde, Universidade Federal de Viçosa, Avenida P.H. Rolfs, s/n, Campus Universitário, CEP: 36.570000, Viçosa, MG, Brazil. Tel.: +55 31 3899 3731; fax: +55 31 3899 2541. E-mail address: [email protected] (H.M. Pinheiro-Sant’Ana).
1. Assemble HACCP team. The food operation should assure that the appropriate product specific knowledge and expertise is available for the development of an effective HACCP plan.
0956-7135/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodcont.2009.05.020
C.M.A. Rodrigues et al. / Food Control 21 (2010) 264–271
2. Describe product. A full description of the product should be drawn up, including relevant safety information. 3. Identify intended use. The intended use should be based on the expected uses of the product by the end consumer. 4. Construct flow diagram. The flow diagram should be constructed by the HACCP team. The flow diagram should cover all steps in the operation. 5. On-site confirmation of flow diagram. The HACCP team should confirm the processing operation against the flow diagram during all stages and hours of operation and amend the flow diagram where appropriate. 6. List all potential hazards associated with each step, conduct a hazard analysis, and consider any measures to control identified hazards. The HACCP team should list all of the hazards that may be reasonably expected to occur at each step from primary production until the point of consumption. 7. Determine Critical Control Points (CCP). The determination of a CCP in the HACCP system can be facilitated by the application of a decision tree, which indicates a logic reasoning approach. 8. Establish critical limits for each CCP. Critical limits must be specified and validated if possible for each Critical Control Point. Criteria often used include measurements of temperature, time, moisture level, available chlorine, and sensory parameters such as visual appearance and texture. 9. Establish a monitoring system for each CCP. The monitoring procedures must be able to detect loss of control at the CCP. 10. Establish corrective actions. The actions must ensure that the CCP has been brought under control. Deviation and product disposition procedures must be documented in the HACCP record keeping. 11. Establish verification procedures. Verification and auditing methods, procedures and tests, including random sampling and analysis, can be used to determine if the HACCP system is working correctly. 12. Establish documentation and record keeping. Efficient and accurate record keeping is essential to the application of a HACCP system. HACCP procedures should be documented. One of the factors determining the nutritional quality of nutrients is their vitamin content, due to its instability. Since the human body is not capable of synthesizing vitamins in sufficient amounts to satisfy its daily needs, diet should supply them. Vitamin losses may occur at the postharvest stage and during meal distribution to consumers. They can be caused by chemical changes that result in lower activity compounds, irreversible binding to other compounds in the food, or by degradation to inactive products. Oxygen, light and complexation with metal frequently play an important role in these losses (Ryley & Kajda, 1994). The recommendation to include vegetables in the diet is based on their low caloric value, high fiber content and significant levels of micronutrients, such as vitamin C (Giannakourou & Taoukis, 2003). However, vegetable shelf life (i.e. that length of time before vegetables are considered unsuitable for sale or consumption) is reduced and these nutrients are frequently exposed to conditions that degrade their quality, especially in terms of vitamins (Prodanov, Sierra, & Vidal-Valverde, 2003). Knowing the main factors affecting vitamin stability can prevent or reduce vitamin losses during food preparation. Consumers have become more aware of the nutritional quality of foods. Both consumers and food manufacturers have become particularly interested in vitamin C since it is one of the most sensitive (including fat-soluble and water-soluble vitamins) to processing and storage conditions, with its degradation being related to several factors, such as: oxygen, pH, light, temperature, and moisture content or water activity (Zanoni, Peri, Nani, & Lavelli,
265
1999; Rojas & Gerschenson, 2001). Vitamin C is frequently used as an indicator of severity of food processing: since it is well retained in foods, the retention percentage of all other vitamins (fat-soluble and water-soluble) should be similar or higher (Özkan, Kirca, & Cemeroglu, 2004). This is the first study, to our knowledge, that analyses vitamin C losses in a real situation and proposes measures to control these losses. Thus, we have opted to conduct a one-off experiment rather than use established data. It is expected that the adoption of control measures, compatible with the HACCP system will help reduce vitamin C losses in foods prepared at food service (FS), also leading to decreased loss of other nutrients. Thus, this study aimed to develop a set of measures that may contribute to improve the nutritional quality of meals at a FS, focusing on vitamin C loss minimization in vegetables. 2. Material and methods 2.1. Raw material The vegetables used in this study were routinely prepared at a FS, with six raw and two cooked preparations being selected and described as follows: – Raw preparations: lettuce (Lactuca sativa L.), carrot (Daucus carota L.), chicory (Cichorium endívia L.), cabbage (Brassica oleracea, var. acephala), white cabbage (Brassica oleracea, var. capitata) and tomato (Lycopersicom esculetum). – Cooked preparations: carrot (Daucus carota L.) and cauliflower (Brassica oleracea, var. botrytis L.). 2.2. Equipment and reagents The following equipments were utilized for vitamin extraction in the samples: microgrinder, model MA 102, Marconi; vacuum pump model CA Fanem; Excelsa Baby II centrifuge, model 206-R, Fanem. The mobile phase was degasified using a vaccum pump model CA Fanem. To measure the mobile phase pH a pHmetro UB-10, Hexis was used. Absorption spectra scanning and vitamin standard quantification were performed using a spectrophotometer UV 1601, Shimadzu. A forced-air circulation oven, model ETC 45 400ND series, Nova Ética, was used for total solids determination. A Sauter D-7470 analytical balance, with four decimal places was used to weigh the samples. The samples were prepared using analytical grade metaphosphoric acid (Merck, Germany), and ultrapure water Milli-QÒ type. High purity grade L-ascorbic acid (Vetec, Brazil) was used as vitamin standard. The following were used for mobile phase preparation: ultrapure water Milli-QÒ type, HPLC grade acetonitrile (Mallinckroat, USA); analytical grade metaphosphoric acid (Merck, Germany), and analytical grade tetrabutylammonium bromide (Vetec, Brazil). Filter paper number JP41 (J. Prolab, Brazil) and sterilized, disposable 4 mL syringes (Rymco, Colombia); HV Millex poliethylene filtration units, 0.45 lm porosity (Millipore, Brazil) were also used. 2.3. Methods 2.3.1. The FS selected and measures adopted A self-managed public FS participated in the study, with a popular standard menu and nutritionists and home economics specialists as part of its staff. This FS was chosen since it was the only self-managed public in town. Besides, its access was easy, because the FS is located at the University where this study was carried out. In 2000, it was renovated and new equipment and utensils were
– – Time control Time and volume of water control Time, temperature and water volume control NH, Nutritional Hazard; NCP, Nutritional Control Points; NCM, Nutritional Control Measures and NCC, Nutritional Control Criteria.
Cooking
Loss due to leaching and high temperature
Yes
Cooking after water starts to boil
– – 20 min before preparation and 1 h before distribution Immersion: volume of water sufficient to cover the vegetables for 10 min (150 ppm of chlorine) Time of cooking: 10 min at 100 °C. The volume of water must be sufficient to cover the vegetables Not applicable Not applicable Peeling close to preparation and distribution Reduction of volume of water and time of immersion No No Yes Yes exposure to heat oxidation exposure to air leaching to to to to Loss Loss Loss Loss Cooked carrot Transport Storage Peeling Hygienization/sanitization
due due due due
– Temperature control Time control Time and water volume control – – 20 min before preparation and 1 h before distribution Immersion: volume of water sufficient to cover the vegetables for 10 min (150 ppm of chlorine) Not applicable Not applicable Peeling close to preparation time Reduction of volume of water and time of immersion No No Yes Yes exposure to heat oxidation exposure to air leaching to to to to due due due due Loss Loss Loss Loss
Storage at room temperature (20–25 °C) for ±3 h Hygienization/sanitization
Raw grated Carrot Transport Storage Peeling Hygienization/sanitization
Time and water volume control Washing of the leaves by portion. Reduction of volume of water and time of immersion Yes
Immersion for 10 min (150 ppm of chlorine); volume of water sufficient to cover the leaves
Temperature control Storage at 15 °C Cold storage Yes
– – Not applicable No
Loss due to exposure to heat and sunlight Degradation due to heat and artificial light Loss through leaching, due to long contact with water
NCC NCM NCP NH Processing stage
2.3.2. Preparation and sample collection In the first phase of the study, the vegetables were prepared according to the establishment’s production routine. Vitamin C content of each vegetable was analyzed before and after preparation, making it possible to analyze the vitamin content under normal preparation and consumption conditions. Samples were collected randomly from different parts of the gastronorms (GN), during vegetable delivery and the end of the period of meal distribution (vegetables were collected only once after 90 min of exposure, simulating the mean exposure time used by the FS). On average, 50 g of each vegetable were collected on three different days, characterizing three repetitions. After collection, the samples were packed in plastic bags, placed in Styrofoam boxes and taken to the Vitamin Analysis Laboratory of the Department of Nutrition and Health of the Federal University of Viçosa. The vegetables were then stored in the refrigerator, at approximately 5 °C, until vitamin extraction after a maximum of 24 h. The chromatographic analyses were performed immediately after extraction. In the second phase of the study, the proposed NCMs for vegetable preparation were adopted. New vegetable samples were collected (three repetitions) and new vitamin C content analyses were performed to verify whether the NCMs were efficient in preserving the vitamin.
Lettuce, chicory and collard Transport
acquired, making it possible to implement the Good Manufacturing Practices (GMPs); in 2004, training was provided to its employees. The implementation of the GMPs allowed the application of the HACCP practice guidelines. WHO defines GMPs as ‘‘that part of quality assurance which ensures that products are consistently produced and controlled to the quality standards appropriate to their intended use and as required by the marketing authorization” (WHO, 1992). GMPs cover all aspects of the manufacturing process: defined manufacturing process; validated critical manufacturing steps; suitable premises, storage, transport; qualified and trained production and quality control personnel; adequate laboratory facilities; approved written procedures and instructions; records to show all steps of defined procedures taken; full traceability of a product through batch processing records and distribution records; and systems for recall and investigation of complaints (WHO, 1997). At the FS, groceries are purchased weekly from a fruit and vegetable producer, except for the leafy vegetables, which are purchased according to the menu needs. The leafy vegetables are supplied by a local farmer, and the others by the Minas Gerais Supply Center (CEASA, MG). Based on the HACCP system principles cited by Almeida (1998) and NACMCF (1998), the following steps were implemented by the participating FS: description of the operational procedures using flow charts of each vegetable selected, including analysis of the following stages: vegetable reception, storage, preparation and distribution; identification of the stages where significant Nutritional Hazards-NH (possible nutrient loss in food due to the adoption of inappropriate techniques and procedures) might occur; identification of Nutritional Control Points-NCP (points that must be corrected to minimize nutrient losses in foods); proposition of Nutritional Control Measures – NCM (procedures adopted to prevent or reduce losses that compromise the nutritional quality of food, maintaining the nutritional risk under control); definition of Nutritional Control Criteria – NCC (procedure adopted for each Nutritional Control Measure-NCM coupled to a Nutritional Control Point – NCP; it is a minimum or maximum of a parameter to be adopted in respect of NCP in order to prevent, eliminate or reduce the risk of loss of nutrients in foods), based on specialized literature, including the following factors: storage and cooking time and temperature, water/food relation, presence of light and oxygen; and definition of monitoring procedures.
Monitoring
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Table 1 Description of the NH associated to vitamin C losses, NCP, NCM, NCC and monitoring procedures in the handling stages of lettuce, chicory, collard, raw carrot and cooked carrot prepared at the food service.
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C.M.A. Rodrigues et al. / Food Control 21 (2010) 264–271 Table 2 Description of the NH associated to vitamin C losses, NCP, NCM, NCC and monitoring procedures in the handle stages of cooked cauliflower, white cabbage and tomato. Processing stage
NH
NCP
NCM
NCC
Monitoring
Transport Storage Slicing
Loss due to exposure to heat Loss due to oxidation Loss due to exposure to air
No No Yes
Loss due to leaching
Yes
Cooking
Loss due to leaching and inadequate temperature
Yes
Cooking after water starts to boil
– – 20 min before preparation and 1 h before distribution Immersion: volume of water sufficient to cover vegetables for 10 min (150 ppm of chlorine) Time of cooking: 10 min at 100 °C. The volume of water must be sufficient to cover the vegetables
– – Time control
Hygienization/ sanitization
Not applicable Not applicable Slicing close to time of distribution Reduction of volume of water and time of immersion
White cabbage
Transport Storage Hygienization/ sanitization
Loss due to exposure to heat Loss due to oxidation Loss due to leaching
No No Yes
Not applicable Not applicable Reduction of volume of water and time of immersion
– – Immersion: volume of water sufficient to cover vegetables for 10 min (150 ppm of chlorine)
– – Time and volume of water control
Tomato
Transport Storage Hygienization/ sanitization
Loss due to exposure to heat Loss due to oxidation Loss due to leaching
No No Yes
Not applicable Not applicable Reduction of volume of water and time of immersion
– – Immersion: volume of water sufficient to cover the vegetables for 10 min (150 ppm of chloride)
– – Time and volume of water control
Cooked cauliflower
Time and volume of water control
Time, temperature and volume of water control
NH, Nutritional Hazard; NCP, Nutritional Control Points; NCM, Nutritional Control Measures and NCC, Nutritional Control Criteria.
2.3.3. Vitamin C extraction and analyses The analyses were carried out in the dark, with care being taken to protect the pigments from light and oxygen, using aluminum foil to cover the glassware, amber flasks and ‘‘black-out” blinds. The conditions for vitamin C extraction and analyses were based on a method proposed by Giannakourou and Taoukis (2003), with some modifications: 5 g of each sample were weighed; 15 mL of 4.5% metaphosphoric acid were added to the sample, which was ground in a microgrinder. The material was then vacuum-filtered through a Büchner funnel using filter paper, and diluted to 25 mL volume with ultra pure water using a volumetric flask. The sample was centrifuged at a speed of 4000 rpm during 15 min and placed in the refrigerator (5 °C) until analysis by High Performance Liquid Chromatography (HPLC). Before injection, the material was again filtered through filtering units. The chromatographic conditions were: high performance liquid chromatograph, Shimadzu, with high pressure pump, model LC-10AT VP; automatic injector with 50 lL loop, model SIL-10AF; UV-Visible, diode array detector, model SPD-M10A; Multi System software model Class VP 6.12, controls up to four systems; Microsorb column RP-18 5, 250 mm in length and 4 mm internal diameter; mobile phase composed of 80% ultra pure water (pH adjusted for 2.2 with metaphosphoric acid), 20% acetonitrile, 10 mM tetrabutylammonium bromide; 1 mL/min flow; run time between 10–15 min for samples and 5 min for standards. The chromatograms were monitored at 238 nm. Analyses were controlled by Multi System software model Class VP 6.1. 2.3.4. Vitamin C standard-curve, identification and quantification After quantification in a spectrophotometer, 5 and 15 lL of AA 1 mg/mL solution and 15 and 30 lL of 4 lL/mL solution were injected to build the standard-curve. Vitamin identification in the vegetable samples was carried out by comparing standard and sample retention times under the same conditions. The spectra of the standard absorption and peaks of interest in the samples were also compared, using the diode array detector.
Vitamin C concentration in the samples was calculated based on the standard-curve and regression equation obtained. The real concentration value in the samples was obtained by calculating the dilutions performed. 2.3.5. Linearity range determination Linearity range was tested under the chromatographic conditions optimized in this study. Injections of increasing volumes (5–50 lL) of the standard solution were performed in triplicate. Linearity was determined based on the results obtained for the peak areas and their respective concentrations, through a linear regression analysis. Linearity was evaluated using the correlation coefficient (R2) obtained (Albalá-Hurtado, Novella-Rodríguez, Veciana-Nogués, & Mariné-Font, 1997). 2.3.6. Vitamin standard recovery analysis Using the extraction procedures and chromatographic conditions optimized in this study, recovery tests were conducted by adding known concentrations of the vitamin C standard into samples of cooked carrot cooked cauliflower, cabbage and raw tomato. To evaluate and determine recovery, the samples were carefully homogenized and weighed in two tubes, to obtain two similar aliquots. The standard solution was added to one of the samples in sufficient concentration to represent 50% of the original vitamin content of each vegetable tested, with the other tube being used as control. Two tubes of each sample were submitted to extraction and analysis procedures. All procedures were carried out in duplicate and the samples were also injected in duplicate. The recovery values were obtained based on the percent difference between the analyzed and added contents. Percent recovery values (%R) were obtained through the following equation:
%R ¼ ðFinal compound content Amount of added compoundÞ =ðInitial amountÞ 100
ð1Þ
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2.3.7. Total solids determination Moisture content of the samples was determined according to the method described by Kawashima and Soares (2003) for green leafy vegetables by applying the time and temperature binome (105 °C/2 h) according to Guinazi (2004). Moisture content was obtained after drying the samples in a forced-air circulation oven followed by chilling in a desiccator (2 h min) and weighing. The following equation was used to calculate moisture content in the samples: Moisture content (%) = (wet weight dry weight)/ wet weight 100. Total solids content was determined by the difference between total sample and moisture contents.
min loss. One of the most important points was lack of temperature and cooking time monitoring as well as immersion time and water volume. The FS routinely sanitizes the vegetables, except for cabbage and cooked carrots, which are just washed under tap water. Carrots and cauliflower were placed in the cooking pot before the water boiled, increasing the chances of losses due to heat and leaching. This behavior was probably due to lack of knowledge or training of the workers. After preparation, the vegetables were stored in a refrigerated pass through (5–8 °C) before distribution, a positive measure to maintain their microbiological and nutritional quality.
3. Results and discussion 3.1. Vitamin C loss stages and definition of control measures
3.2. Vitamin C qualitative analysis, linearity range, and vitamin standard recovery
After analysis of the operational procedures, the manipulation procedure stages, where significant hazards for vitamin C losses might occur, were identified. The NCMs and their respective monitoring formats were associated to these hazards, aimed at controlling vitamin losses in the vegetables (Tables 1 and 2). The NCMs were experimentally adopted at the FS to control vitamin C losses in the samples, after their implementation. It was observed that following delivery, the leafy vegetables were exposed for a prolonged period of time (±3 h) at room temperature (20–27 °C) until sanitized. One of the adopted NCMs was to store the leafy vegetables under refrigeration (10 °C) until sanitization. Following the FS routine, the remaining vegetables were also stored in the refrigerator (8–10 °C), thus reducing vita-
Fig. 1 shows typical chromatographic profiles of two of the samples analyzed in this study. The extraction technique resulted in samples with reduced amounts of interfering compounds, making it easier to separate the compounds of interest. The chromatographic conditions used allowed a good ascorbic acid resolution, which ensured safe vitamin quantification in the samples. The diode array detector provided important spectral information for ascorbic acid identification in the samples. Fig. 2 shows an example of overlapping between the vitamin standard absorption spectra and the peak of interest in a raw collard sample. The linearity range obtained for AA was wide (12.3–80.5 mg), allowing the collection of reliable data in the studied ranges. The correlation coefficient (R2) was equal to 0.977.
AA
Absorvance (mAU)
1400 1200 1000 800 600 400 200 0 0
2
4
6
8
10
12
14
12
14
Retention Time (min) 600
Absorvance (mAU)
500 400 300 AA 200 100 0 0
2
4
6
8
10
Retention Time (min) Fig. 1. Analysis by HPLC of ascorbic acid (AA) raw collard (A) and lettuce (B). Chromatographic conditions: Mobile phase: 80% of ultrapure water (pH adjusted to 2.2 with metaphosphoric acid) + 20% of acetonitrile; + 10 mM of bromide tetrabutylammonium; Microsorb RP-18 column; diode array detector (detection at 238 nm). Flow: 1 mL/min; injection volume: 30 lL.
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500
Raw Collard sample
Absorbance (mAU)
Standard 2.92 min
400 300 200 100 0 200
220
240
260
280
300
320
340
360
Wavelength (nm) Fig. 2. Absorption spectra overlap of AA standard of raw collard analysed by the diode array detector.
AA recovery percentage in the four vegetables ranged between 69.24% and 93.35%. Recovery percentage was lower in cooked cauliflower samples. A broader exposure of the chopped vegetable might have influenced this low recovery rate. The cauliflower tissue becomes very soft after cooking and sectioning into small pieces (to make grinding easier) might have increased the surface in contact with air, leading to partial degradation of the vitamin. Rizzolo, Brambilla, Valsecchi, and Eccher-Zerbini (2002) found similar results in AA recovery rates in pears (between 60% and 85%). The authors reported that AA recovery is significantly affected by small temperature variations and exposure to light during extraction. 3.3. Ascorbic acid content in vegetables AA contents in the studied vegetables, in natura and after routine preparation at the institutional restaurant, are shown in Table 3. AA content varied greatly among the studied vegetables, but, in general, the values were compatible with those presented by the American Guide of Food Composition (USDA, 2008). It should be noted that this table reflects nutrient contents in vegetables cultivated in the United States. In addition, vegetable variety, mode of cultivation, and soil type can influence nutrient content in foods (Campos, 2006). Some authors found similar AA values for cauliflower, cabbage and tomato (Lee & Kader, 2000). Gökmen, Kahraman, Ddemir, and Acar (2000) found lower values for tomato and cabbage (7.9 and 5.5 mg/100 g, respectively). Della Lucia, Campos, Tomazini, and Pinheiro-Sant’Ana (2006) found AA contents ranging between 11.66 and 16.20 mg/100 g after standard processing conditions. Few studies are found in the literature associating vitamin C content in lettuce, carrot, chicory, collard, cauliflower, cabbage,
and tomato and on the effect preparation and cooking methods can have on their stability. However, Della Lucia et al. (2006) found contents of 88.27 and 99.71 mg/100 g in stir-fried collard, which are higher than those found in this study, since stir-fried vegetables concentrate nutrients by weight units. Considering the expression of AA contents on a dry basis, the vegetables showing the highest vitamin content reduction were chicory and lettuce. Collard, however, had a smaller loss. Type of slicing is one of the factors that might have contributed to the percent difference between these two vegetables. Collard is sliced using a mechanic slicer, while chicory is manually sliced using a knife. Lettuce leaf is more sensitive to transportation and storage damages (Marques, Baldotto, Santos, & Oliveira, 2003) and even to type of cutting, while collards and chicory leaves are more resistant. Among the cooked vegetables, cauliflower presented a higher AA loss percentage. Grated raw carrot presented a smaller loss than cooked carrot, as expected. Tomato and cabbage presented the lowest AA losses. After analysis of AA content in the vegetables under real preparation conditions, the NCMs proposed were duly monitored to verify their efficiency in retaining vitamin in the foods being tested. AA contents in vegetables in natura and after preparation, adopting the NCMs, are show in Table 4. Fig. 3 shows AA retention percentage in the vegetables analyzed at the FS, before and after adoption of the NCMs. Overall, the vegetables showed higher vitamin retention after NCM adoption. Losses were reduced in approximately 88%, 49% and 45% for collard, lettuce and chicory, respectively, and approximately 30% for cauliflower. Although loss percentage increased in cabbage, it should be emphasized that this vegetable was duly sanitized, a procedure not previously conducted.
Table 3 Ascorbic acid in vegetables in natura and after preparation at food service, before the adoption of the Nutritional Control Measures (NCMs). Vegetable
Lettuce Cooked carrot Raw grated carrot Chicory Collard Cooked cauliflower White cabbage Tomato *
In natura
After preparation
Wet base* (mg/100 g)
Dry base* (mg/100 g)
Wet base* (mg/100 g)
Dry base* (mg/100 g)
Losses in dry base (%)
9.2(3.1–18.4) 8.4(5.5–11.1) 10.1(9.3-10.7) 15.7(5.7–24.6) 98.9(94.4–104) 52.7(42.0–61.6) 33.9(21.6–40.4) 15.9(14.7–16.2)
235(92.7–428) 84.5(65.1–105) 107(94.5–126) 228(74.0–325) 812(708–922) 570(465–741) 545(401–716) 294(278–305)
5.8(3.8–7.6) 6.7(5.4–8.1) 7.5(5.5–8.5) 4.5(2.5–6.1) 61.1(50.1–71.9) 10.9(8.3–16.1) 31.1(20.9–38.4) 13.3(10.1–15.6)
126(47.4–171) 51.6(45.5–63.4) 74.2(60.5–81.0) 72.5(45.8–88.0) 577(572–581) 156(111–238) 482(382–593) 229(164–292)
46.5 38.9 30.8 68.2 28.9 72.6 11.6 22.2
Means of three repetitions (range).
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Table 4 Ascorbic acid in vegetables in natura and after preparation at food service, after the adoption of the Nutritional Control Measures (NCMs). Vegetable
In natura
After preparation *
Lettuce Cooked Carrot Grated raw carrot Chicory Collard Cooked cauliflower White cabbage Tomato *
*
Wet basis (mg/100 g)
Dry basis (mg/100 g)
Wet basis* (mg/100 g)
Dry basis* (mg/100 g)
Losses in dry basis (%)
8.1(6.1–10.9) 7.8(6.6–9.3) 6.9(6.5–7.3) 8.7(6.9–10.3) 95.3(90.2–105) 49.9(48.4–50.7) 29.4(22.2–38.1) 19.9(15.6–24.6)
193(153–272) 71.5(63.4–83.6) 69.1(63.4–72.6) 134(113–157) 812(723–892) 748(496–875) 438(336–605) 348(268–460)
5.4(4.1–7.5) 6.3(5.6–6.6) 6.7(6.5–7.1) 3.9(3.1–4.1) 84.7(73.1–99.8) 21.2(20.0–23.4) 26.6(21.4–35.4) 14.5(12.4–15.6)
147(90.2–229) 58.4(48.4–63.4) 60.9(59.1–63.4) 84.1(52.2–109) 784(599–950) 374(339–405) 392(285–553) 260(194–299)
23.7 18.4 8.4 37.5 3.4 50.1 10.6 25.2
Means of three repetitions (range).
120 96.6
AA Retention (%)
100
60
81.6
76.3
80 53.5
61.1
88.4 89.4
87.6
77.8 74.8
71.1
69.1
62.5 49.9
40
31.8
27.4
20 0
Lettuce
Cooked Raw Grated Carrot Carrot
Chicory
Before adoption of NCM
Collard
Cooked White Cauliflower Cabbage
Tomato
After adoption of NCM
Fig. 3. AA retention in vegetables prepared in food service, before and after the adoption of the Nutritional Control Measures.
AA retention was similar for tomato and cabbage before and after NCM adoption. It is worth mentioning that these vegetables presented smaller AA loss percentages from reception to distribution. However, in a study by Campos (2006), storage under refrigeration favored AA retention in tomatoes, with mean retention of 89% under 10 °C and 81% under room temperature (24 °C mean). The higher vitamin C retention in cooked vegetables confirms the efficiency of the NCMs regarding water volume, cooking time and allowing the water to boil before beginning cooking. Vitamin C loss reduction in most of the vegetables analyzed was also a result of reduced preparation time. Before NCM adoption, the vegetables would be ready for consumption within, approximately, 3 h before distribution. After the measures were adopted, this time was reduced to approximately 1 h. No studies were found in the literature linking the use of the HACCP system and vitamin loss control in vegetables. However, in a study conducted by Fernandes, Dutra, and Proença (2007), the Nutritional and Sensorial Quality Evaluation System (NSQE) was applied in combination with the HACCP system. This study evaluates the nutritional and sensorial criteria applied to black and red beans prepared at a FS. The findings point to the need to soak the grains to minimize their antinutritional factors, improving their sensorial quality, as shown by a higher acceptance by tasters, and, though not measured, increased grain digestibility. Although the analysis of nutrients, especially vitamins, was not conducted in this study, the NSQE system may be considered a helpful tool in maintaining nutritional characteristics. In a FS case study aimed to implement the HACCP system principles in meat preparation, Hering, Proença, Sousa, and Veiros (2006) concluded that possible corrective actions could be associ-
ated not only with hygienic–sanitary control, but also with improved nutritional and sensorial quality of the preparations. Although vitamin content determination was not conducted in this study, it must be emphasized that the nutritional value of meat might be compromised during pre-preparation (freezing, thawing, and cutting) and preparation (cooking),with meats losing expressive amounts of liquid, resulting in water-soluble nutrient losses (Pires, Rosado, Azevedo, Neves, & Miranda, 2002). Thus, determination of nutritional control measures can be useful under this aspect. Soriano, Moltó, and Mañes (2002) suggested the incorporation of a nutritional concept into the HACCP methodology. These authors argued that this initiative would eventually improve the quality of life of FS users. Our study showed that some procedures can be adopted to prevent vitamin C losses in vegetables prepared at FS, such as: short storage periods; vegetable storage under refrigeration; slicing vegetables close to serving time and in larger pieces to reduce exposure to oxygen. Also, vegetable hygienization and sanitation should be efficient enough to eliminate dirt and contamination. However, time should be monitored to avoid excessive contact with water and leaching losses. It is important to take into account that safety of raw vegetables is a major issue and should not be compromised in the name of vitamin C losses control. This stage should, whenever possible, precede the slicing stage, since it causes a higher contact with water, increasing not only water-soluble vitamin losses, but also the loss of other micronutrients, such as minerals, and of water-soluble components, such as pigments, sugars and starch, responsible for the sensorial quality of these products. Cooking water should be in a sufficient amount to cover
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the vegetables, and the cooking methods, whenever possible, should be steam cooking, pressure cooking or stir-frying in oil, to avoid direct contact of the nutrients with water. When not possible (as in this study, there was no food steamer available), cooking water should be used in the preparation of soups and sauces to use the water-soluble vitamins lost through leaching. Vegetable cooking time and temperature should be monitored. Meal distribution should occur 1 hour after preparation at most, provided vegetables are kept under refrigeration. 4. Conclusions Assuming that vitamin C losses are indicators of loss of other vitamins, the NCMs can be effective in minimizing vitamin losses in vegetables prepared at FSs. This study concluded that the NCMs are effective in reducing vitamin C losses in vegetables. The Good Manufacturing Practices utilized throughout the development of this study comprise a larger concept, involving not only widely disseminated hygienic-sanitary control but also aspects related to preservation of the nutritional value of the vegetables. In this study, we have shown that some procedures can be adopted to prevent vitamin C losses in vegetables prepared at FSs, such as: shorter storage periods; vegetable storage under refrigeration; slicing vegetables close to serving time and in larger pieces, adequate hygienization, controlling cooking time and temperature and shorter time between preparation and meal distribution. Through the determination of NCPs and the establishment of corrective actions, it was possible to obtain vegetables with higher nutritional quality. This study can be considered the starting point for further research adopting some HACCP system principles to control the nutritional quality of meals prepared at FSs, as studies of this nature are practically nonexistent internationally. We suggest the implementation of other studies to assess the losses of vitamin C in each stage of the handling of vegetables, so that control measures can be implemented in a more punctual way. The results obtained in this study on the vitamin C content in the vegetables analyzed can contribute to their nutritional characterization, as similar studies are not available in Brazil. Acknowledgement The authors thank PIBIC/CNPq and CAPES for the financial support. References Albalá-Hurtado, S., Novella-Rodríguez, S., Veciana-Nogués, M. T., & Mariné-Font, A. (1997). Determination of vitamins A and E in infant milk formulae by highperformance liquid chromatography. Journal of Chromatography A, 778, 243–246. Almeida, C. R. (1998). O sistema HACCP como instrumento para garantir a inocuidade dos alimentos. Higiene Alimentar, 12(53), 12–20. Badaró, A. C. L. (2007). Avaliação do nível de adoção das boas práticas de manipulação de alimentos em restaurantes do município de Ipatinga, Minas Gerais (75 p). Dissertation (Master’s in Nutrition Science). Federal University of Viçosa.
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Della Lucia, C. M., Campos, F. M., Tomazini, A. P. B. & Pinheiro-Sant’Ana, H. M. (2006). Validação de critérios para controle de perdas de vitamina C em hortaliças preparadas em unidade hospitalar. In Anais do XIX Congresso Brasileiro de Nutrição, São Paulo. FAO Food and Agriculture Organization. (1997). Hazard analysis and critical control point (HACCP) system and guidelines for its application.