Freeze drying technique for microencapsulation of Garcinia fruit extract and its effect on bread quality

Journal of Food Engineering 117 (2013) 513–520

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Freeze drying technique for microencapsulation of Garcinia fruit extract and its effect on bread quality P.N. Ezhilarasi a, D. Indrani b, B.S. Jena c, C. Anandharamakrishnan a,⇑ a

Department of Food Engineering, CSIR-Central Food Technological Research Institute, Mysore 570 020, India Flour Milling, Baking and Confectionery Technology Department, CSIR-Central Food Technological Research Institute, Mysore 570 020, India c R&D Planning and Bioresource Engineering, CSIR-Institute of Minerals and Materials Technology, Bhubaneswar 751 013, India1 b

a r t i c l e

i n f o

Article history: Available online 23 January 2013 Keywords: Microencapsulation Garcinia cowa Enriched bread Freeze drying Whey protein isolate Maltodextrin

a b s t r a c t Microencapsulation is an enduring technology for protection and controlled release of food ingredients. The Garcinia cowa fruit rinds are rich source of ()-hydroxycitric acid (HCA), which is reported to have various health benefits. But, HCA is hygroscopic in nature and thermally sensitive. Hence, G. cowa fruit extract was microencapsulated using three different wall materials such as whey protein isolate (WPI), maltodextrin (MD) and combination of whey protein isolate and maltodextrin (WPI + MD in 1:1 ratio) by freeze drying at 30% concentration. The microencapsulated powders were evaluated for their impact on bread quality and free HCA concentration. The microcapsules exhibited wider particle size range of 15–100 lm and HPLC analysis showed that all the three encapsulates yielded higher free (above 85%) and net (above 90%) HCA recovery. Moreover, bread with WPI encapsulates exhibited higher volume, softer crumb texture, desirable colour and sensory attributes and had higher free HCA concentration. This indicated that WPI has excellent encapsulation efficiency than other two wall materials during bread baking. Ó 2013 Elsevier Ltd. All rights reserved.

1. Introduction Microencapsulation is a technology for packing solids, liquids or gaseous materials in miniature, sealed capsules to release their contents at controlled rates under specific conditions. It protects the core from adverse environmental conditions, improve shelf life of a product and promote controlled release (Shahidi and Han, 1993). Freeze drying is most suitable technique for dehydration of all heat-sensitive materials and also for microencapsulation (Desai and Park, 2005). It is a multistage operation stabilizing materials through four main operations such as freezing, sublimation, desorption and finally storage (Mascarenhas et al., 1997). The efficiency of protection or controlled release mainly depends on the composition and structure of wall material (Young et al., 1993). Most commonly used wall materials are gum arabic, maltodextrin, emulsifying starches, whey protein, etc. Whey protein possessed unsurpassed nutritional quality and inherent functional properties that meet the demands of encapsulation. Maltodextrin are used as encapsulating material due to their water solubility, low viscosity and low sugar content (Avaltroni et al., 2004). Gum arabic is also an effective encapsulating agent due to its protective colloid functionality. But the cost, limited supply and quality variations of gum ⇑ Corresponding author. Tel.: +91 821 2514310; fax: +91 821 2517233. 1

E-mail address: [email protected] (C. Anandharamakrishnan). Present address.

0260-8774/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jfoodeng.2013.01.009

arabic have restricted its use for encapsulation and became an another area of research to find alternative biopolymer with same or higher encapsulation efficiency (You-Jin et al., 2003). The blends of biopolymers as wall materials can increase the encapsulation efficiency and shelf life of microcapsules due to interaction of their properties (Perez-Alonso et al., 2009). Hence, the combination of whey protein and maltodextrin were chosen to analyse their encapsulating properties in comparison to them as a single wall material. During last decades, scientific interest in functional foods has increased due to its protective effects on various degenerative diseases. Garcinia cowa is one of the functional foods due to its excellent dietary source of ()-hydroxycitric acid (HCA) in their fruit rinds (Jena et al., 2002a). Various studies reported that, HCA regulated fatty acid synthesis at a dosage of 1.32 mmoles/kg body weight of rat (Sullivan et al., 1977), lipogenesis at 1500 mg/day (Kovacs and Westerterp-Plantenga, 2006), appetite at 1320 mg/ day (Thom, 1996), and weight loss at 1200–2800 mg/day (Ramos et al., 1995; Preuss et al., 2005). It was also attributed to cardioprotection, anti-diabetic effect, correct conditions of lipid abnormalities and enhance endurance in exercise (Jena et al., 2002b). The published literatures had reported several mechanisms of HCA action on weight management such as by inhibition of ATP-citrate lyase, which slows the production of fatty acids, cholesterol, and triglycerides with the net effect of reduced fat production and storage (Clouatre and Rosenbaum, 1994). It also regulates body weight

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through inhibition of malonyl-CoA formation in fatty acid synthesis pathway and regulation of leptin and insulin plasma levels (Hayamizu et al., 2003). But, the native form of HCA (free HCA naturally available in fruit) is thermally sensitive and become lactonized during evaporation and drying (Krishanmurthy et al., 1982), which is biologically less active. Moreover, the hygroscopic nature of HCA makes it unsuitable for its use in tablets, capsules or as powders. Microencapsulation of Garcinia fruit extract can convert them into shelf stable particulate powder. Moreover, it prevents the undesirable interactions of bioactive compounds with the carrier food matrix, when incorporated in food stuffs (Champagne and Fustier, 2007). In the previous study, Pillai et al. (2012), investigated the effect of spray drying conditions and wall (whey protein isolate) to core (Garcinia fruit extract) ratio on microencapsulation efficiency. Then, microcapsules were incorporated in pasta and found that spray-dried at 90 °C outlet temperature and 1.5:1 wall-to-core ratio exhibited higher antioxidant activity as well as better cooking and sensory characteristics. Incorporation of microencapsulated bioactive compounds into foods is essential to increase their intake and only few studies have performed and analysed their effect on food quality. Moreover, bread is an appropriate foodstuff to incorporate microencapsulates. The main objective of this study was to investigate the effect of wall materials types (whey protein isolate, maltodextrin and the combination of whey protein isolate and maltodextrin) on microencapsulation of G. cowa fruit extract using freeze drying. Further, these encapsulated powders were incorporated into bread to investigate their impact on bread quality and HCA concentration after bread baking. 2. Materials and methods 2.1. Materials Dried G. cowa fruit rinds were obtained from Assam, India and whey protein isolate (WPI) from British Nutrition (Bangalore, India). Maltodextrin (Dextrose Equivalent value as 20) was acquired from Loba Chemie (Mumbai, India). Wheat flour, sugar, fat, salt and yeast, were procured from local market in Mysore, India. All other chemicals and reagents were of analytical grade. 2.2. Microencapsulation of Garcinia extract One kg dried fruit rinds of G. cowa was soaked overnight in water, autoclaved for 30 min, filtered and the extract was concentrated to 30% (w/w-dry weight solid) using a flash evaporator (Buchi, Switzerland) at 60 °C (less HCA degradation due to short time of evaporation under vacuum). Further, concentrated extract was encapsulated using three different wall materials such as whey protein isolate (WPI), maltodextrin (MD) and combination of whey protein isolate and maltodextrin (WPI + MD). 20 g of each wall material was mixed with the 66.6 g of concentrated fruit extract (containing 20 g of solid) and 46.7 g of water to achieve the 30% total concentration and 1:1 wall to core ratio. All the three samples were stirred gently with magnetic stirrer for 30 min to dissolve solid particles prior to freeze drying. Then the samples were freeze dried using pilot scale freeze dryer at 40 to 30 °C. The entire freeze drying process was carried out in 20 h. The microencapsulated powders were collected, packed in polythene bags and stored in a dessicator.

of 12 h at 110 ± 2 °C to a constant mass. From the initial and final weights, moisture content of the samples was calculated on wet basis. The test was performed in triplicate and the average values were used to calculate the final moisture. 2.4. Morphology studies The morphology of encapsulated freeze dried powders was examined using Scanning Electron Microscope (Leo 435 VP, Leo Electronic Systems, Cambridge, UK). The powders were mounted on the specimen holder and sputter-coated with gold (2 min, 2 mbar). Then transferred to the microscope where its images were observed at 15 kV and a vacuum of 9.75  105 torr. 2.5. Particle size analysis Particle diameter of encapsulated powders was measured using a laser light diffraction instrument, Malvern Mastersizer (Malvern Instruments, Malvern, UK). Small amount of sample was suspended in iso-butanol (99.9%) using magnetic agitation, and the particle size distribution was monitored during each measurement until successive readings became constant. 2.6. RP-HPLC analysis of HCA The HCA content (free and lactone HCA) in the feed liquid (Garcinia water extract alone) and the encapsulated powders were analysed using reversed phase HPLC (RP-HPLC) according to the method described by Jayaprakasha and Sakariah (2000). An analytical HPLC (1100 series, Agilent technologies, North Point, Hong kong, manual injector and quaternary pump) equipped with C18 column (4.6  250 mm) with 5 lm of pore size was used. 20 ll of each sample was manually injected into the column with 8 mM sulphuric acid as mobile phase. Elution of samples and mobile phase were carried out at a flow rate of 0.7 ml/min at 65 bar pressure and 25 °C column temperature under isocratic conditions. HCA detection was performed by a UV–visible spectrophotometer SPD6AV at a wavelength of 210 nm. On the injection of each sample, free HCA and lactone HCA were identified by means of their specific retention time and peaks were quantified by comparing peak areas with HCA standard peaks [pure HCA was prepared from the calcium salt of HCA (sigma Chemicals, USA) by using ion exchange method to separate the free HCA]. Then analysis of each sample was carried out in triplicates and the average peak area was used to calculate the HCA content in the feed and microencapsulated powder. Further, standard HCA was heated at 90 °C for 60 min and analysed by RP-HPLC to verify the heat induced lactone HCA formation. 2.7. Microencapsulation efficiency The free HCA recovery (free HCA alone) and net HCA recovery (free HCA and lactone HCA) during freeze drying were obtained from the HCA content of the feed liquid and encapsulated powders. Hence, the microencapsulation efficiency (net HCA recovery) was estimated using the following formula:

Encapsulation efficiency ð%Þ ¼ ðHCA content in powder=HCA content in feed liquidÞ  100 ð1Þ

2.3. Moisture content analysis

2.8. Bread making

The average moisture content of encapsulated powders was measured gravimetrically by oven drying method using hot air oven (Industrial and laboratory tools corporation, Chennai, India). A known mass of the sample (0.5 g) was dried in oven for a period

Microencapsulated powders were incorporated into wheat flour along with other ingredients for bread preparation. Wheat flour and Garcinia powder (with and without encapsulation) were taken in the ratio of 100: 2 for bread making. Based on the screening study

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of various percentages of microencapsulated powders on the bread quality along with the functionality and safety limits of HCA, 2 g of powder was incorporated in bread to impart functionality in bread without any quality deterioration. The dough was prepared by mixing 2 g of microencapsulated powders in 100 g of wheat flour, 12 g of sugar, 3 g of fat, 1.5 g of salt, 2.5 g of yeast, 64 ml of water, along with combination of additives (4 g of dry gluten powder, sodium stearoyl lactylate, 0.002 g of fungal a-amylase). All the ingredients were mixed in a mixer (Hobart Model N-50, Offenburg, Germany), followed by fermentation in a proofing chamber (30 °C and 75% relative humidity) for 90 min, then remixed, again fermented for 25 min, moulded and proofed (30 °C and 85% relative humidity) for 55 min. Further, the proofed dough was baked in a baking oven (Serial No. 965, AVP, Queensland, Australia) for 25 min at 220 °C. Finally, the baked bread was cooled to room temperature for 2 h and subjected to further analysis. The control bread was also prepared under conditions mentioned above without incorporation of any encapsulated powders and additives. 2.9. Analysis of bread quality characteristics Loaf volume of bread was determined by the rapeseed displacement method (Pierce and Walker, 1987) using standard volumemeasuring apparatus (National manufacturing co., Lincoln, Netherland). The moisture content and ash content of bread samples were analysed according to AACC method (2000). The crumb firmness was also determined according to AACC (2000) standard method using a texture analyser (Model Tahdi, Stable Microsystems, Surrey, UK), which was equipped with plunger diameter of 35 mm, plunger speed of 100 mm per minute, load cell 10 kg. For firmness analysis 25-mm thick bread slices were force tested against 25% compression. The crumb colour of breads was analysed using Hunter Lab colour measuring system (Labscan XE, Hunter Associates Laboratory Inc., Reston, Virginia, USA) with incandescent light as standard illuminant. Measured values were expressed as luminosity (L), red versus green (a), yellow versus blue (b) and total colour difference (DE). The loaf quality and sensory attributes of bread were evaluated by a panel consisting of 10 semi-trained panelists. The panelist evaluated the sensory attributes such as crust colour, shape, crumb colour and taste, with maximum score of 10 for each attribute and the score of 15 for texture and grain. The overall sensory score (maximum of 70) was computed by the addition of all the above mentioned sensory characteristics scores (Indrani et al., 2003). 2.10. Analysis of HCA content in bread The HCA content (free HCA) of microencapsulates and water extract incorporated breads were analysed using RP-HPLC according to the method described by Jayaprakasha and Sakariah (2000). The analysis was carried out in similar conditions as mentioned in the RP-HPLC analysis of HCA of microencapsulated powders. The analysis of each sample was carried out in triplicates and the average peak area was used to calculate the HCA content in breads. 2.11. Statistical analysis Results were statistically analysed by t test (test of significance for the difference between two means) using Microsoft excel software and the differences at P < 0.05 were considered as significant. 3. Results and discussion The influence of wall materials on encapsulation of Garcinia extract and their effect on bread quality are discussed in the following sub sections.

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3.1. Moisture content analysis The average percentage moisture content of freeze dried WPI, MD and WPI + MD encapsulates were 15.65%, 12.56% and 11.53% respectively. The results indicated that all the three encapsulated powders have slightly higher moisture content (above 10%) due to low temperature (40 to 30 °C) application in freeze drying technique. The higher temperature difference between the drying medium and particles is required to increase the rate of heat transfer into particles, which provides the driving force for moisture removal (Goula and Adamopoulos, 2010). Moreover, sublimation of ice crystal during freeze-drying leaves a porous structure (Anandharamakrishnan et al., 2010). The lower freezing temperature (40 °C) results in smaller pore size in the freeze-dried systems due to higher cooling rate and increased nucleation (Harnkarnsujarita et al., 2012). These small pores effectively resist mass transfer and act as a barrier against sublimation (Pikal et al., 2002). Consequentially, it resulted in higher moisture in the final product. Comparatively WPI encapsulates had higher moisture content due to their ability to bind a great number of water molecules through hydrogen bonds. During freezing, increase in concentration of protein in the solution, can induce aggregation (Franks and Hatley, 1991) and make the interstitial water becomes less available for freezing (Meza et al., 2010). Thus, moisture content increased in the WPI encapsulates. 3.2. Particle size analysis and morphology The microcapsules of Garcinia fruit extract with different wall materials had a particle size ranging from 15–100 lm. The use of different wall materials had significant influence on particle diameter. MD encapsulated particles exhibited higher particle diameter (40–100 lm) than WPI (20–70 lm) and WPI + MD (15–100 lm) encapsulated particles due to their stickiness and aggregation of the particles. The larger size of the particles were due to the low temperature involved in freeze-drying and lack of forces for breaking up the frozen liquid into droplets or to substantially alter their surface topology during the drying process (Chen et al., 2011). The SEM micrographs (Fig. 1a–d) highlighted the effects of freeze drying on surface morphology of the particles. The surface morphology of freeze dried unencapsulated Garcinia fruit extract (Fig. 1a) clearly showed the hygroscopic nature of Garcinia fruit extract. This can be attributed to the presence of higher amount of hydroxycitric acid in the fruit rinds. Generally, the fruit juices and purees rich in organic acids such as citric, malic and tartaric acid as more than 90% of the solids have sticky behaviour (Dolinsky et al., 2000). Fig. 1b–d depicts the morphology of microencapsulated freeze dried particles. The particles exhibited larger size and resembled broken glass or flake-like structure. Freeze dried powders exhibited slight variations in their surface morphology due to the properties of encapsulating material. Many studies have reported a similar morphology for freeze dried microcapsules (Anandharamakrishnan et al., 2010). The pores were clearly noticed in WPI encapsulates (Fig. 1b) as well as in WPI + MD encapsulates (Fig. 1d) due to sublimation of smaller ice crystal during freeze drying as indicated earlier (Anandharamakrishnan et al., 2010). During freeze-drying, ice supported the frozen structure, and once ice removed by the sublimation, the WPI and WPI + MD encapsulates retained the pore structure. The MD encapsulates exhibited stickiness, aggregation of particles, loss of porous structure and resulted in caking due to increased moisture absorption of maltodextrin (Fig. 1c). This may be due to the higher dextrose equivalent value (20) of maltodextrins, that slowly develop stickiness and reach a state of non-adhesion slower than maltodextrin of low dextrose equivalent value (Goula and Adamopoulos, 2008). Water has plasticizing effect on

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Fig. 1. SEM micrograph of microencapsulated powders (S – stickiness, P – pores). Magnification: 1000X.

amorphous materials because it can disturb hydrogen bonds between carbohydrate chains and as a consequence, decrease the glass transition temperature and increase the water content of amorphous materials (Kilburn et al., 2005). Hence, water absorbs on particle surfaces forming a saturated solution and thereby makes the particles sticky and capable of forming liquid bridges (Downton et al., 1982). 3.3. Microencapsulation efficiency The percentage of free HCA recovery and net HCA recovery of encapsulated powders is depicted in Fig. 2. Free HCA eluted at a retention time of 9.2 min and lactone HCA at 8.1 min. Various reports suggested that polyphenols are heat labile compounds and susceptible to degradation on drying at higher temperature (Lin et al., 2012). All the three encapsulates yielded almost higher free (above 85%) and net (above 90%) recovery (Fig. 2). This can be due to low temperature application (40 to 30 °C) in all the three stages of freeze drying. Freeze-drying removes water from a frozen sample by sublimation and desorption. Freezing involved formation of ice nuclei at below 0 °C (Craig et al., 1999). In primary drying stage ice sublimed at low temperature and low pressure (Mascarenhas et al., 1997). During secondary drying stage, the slight increase in temperature removes the residual moisture which was due to the bound and unfrozen water (Fissore et al., 2010). So, the freeze drying had well protected HCA from thermal exposure and reduced the conversion of free HCA to Lactone HCA. Thus, all the three encapsulates yielded higher HCA recovery without significant difference among them. Zubair et al. (2011) reported the maximum retention of phenolic compounds in freeze drying of Plantago major leaves than the other drying techniques

Fig. 2. Effect of wall materials on free and net HCA recovery of microencapsulated powders. WPI – Whey protein isolate encapsulates; MD – maltodextrin encapsulates; WPI + MD – Whey protein isolate + maltodextrin encapsulates (SD of free HCA recovery: WPI: 4.9; MD: 0.7; WPI + MD: 2.12; SD of net HCA recovery: WPI: 4.09; MD: 0.7; WPI + MD: 2.12; no. of replications: 3).

that applied higher temperature. Similarly, Lin et al. (2012) also reported that freeze drying of Rabdosia serra leaves retained higher amount of polyphenols than air drying and sun drying methods. Freeze-drying, can be considered as a favourable drying technique for protecting the thermolabile constituents due to their very low temperature and oxygen-free environment (Borchani et al., 2011). Besides, the low temperature application in freeze drying, encapsulation of Garcinia fruit extract using wall materials offered additional protection to HCA from degradation. Hence, the encap-

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P.N. Ezhilarasi et al. / Journal of Food Engineering 117 (2013) 513–520 Table 1 Effect of incorporation of freeze dried microcapsules of Garcinia cowa extract on bread quality characteristics and HCA concentration. Bread samples

Moisture content (%)

Ash content (%)

Volume (cc)

Crumb firmness (g)

Control Extract WPI MD WPI + MD

30.6 ± 0.90 29.99 ± 1.02 31.6 ± 1.05 30.35 ± 0.97 30.7 ± 0.92

1.29 ± 0.012 1.26 ± 0.007 1.13 ± 0.002 1.26 ± 0.004 1.27 ± 0.004

600 ± 7.07 485 ± 3.53 530 ± 3.53 505 ± 3.53 505 ± 3.53

540.4 ± 74.6 988 ± 95.16 774 ± 45.6 793 ± 6.17 814 ± 6.17

Colour analysis 



L

a

79.29 ± 0.75 68.17 ± 1.21 73.93 ± 0.40 70.66 ± 1.39 72.05 ± 1.03

0.28 ± 0.045 4.54 ± 0.37 2.82 ± 0.18 3.89 ± 0.11 3.33 ± 0.20



b

DE

17.09 ± 0.56 22.28 ± 0.80 21.44 ± 0.58 21.09 ± 0.19 21.48 ± 0.84

20.45 ± 0.60 32.72 ± 1.24 27.14 ± 0.52 30.04 ± 1.27 28.86 ± 0.96

Free HCA concentration mg/100 g – 283 ± 2.3 525 ± 3.5 484 ± 2.8 487 ± 3.3

Data are presented as mean ± SD. Moisture content, ash content and volume: no. of replications: 2. Crumb firmness and colour analysis: no. of replications: 4. HCA concentration: no. of replications: 3.

sulation of Garcinia extract using freeze drying resulted in higher free and net HCA recovery. Sanchez et al. (2011) also reported 97% retention in the encapsulation of red wine polyphenols through freeze drying. Moreover, there was less variation in the percentage of net HCA recovery among the three encapsulated powders (just varied from 90% to 97%). These results indicated that all the three wall materials had excellent encapsulation efficiency during freeze drying. 3.4. Moisture content and ash content of bread Table 1 revealed the percentage of moisture and ash content of bread samples. The mass transfer mechanisms inside the dough can be due to diffusion along with evaporation and condensation (Thorvaldsson and Janestad, 1999). The transport of water is driven by the gradients in water content. During baking, water removes quickly from the dough surface, offers optimum conditions for a Maillard reaction (Kent-Jones and Amos, 1967). However, once the crust is formed, water vapour diffusion is restricted from pores to the dough surface (Mondal and Datta, 2008). The water loss is strongly related to the temperature in the crust because as the crust dehydrates, temperature increases. The water extract incorporated bread had slightly lower moisture content than breads with microencapsulates (Table 1). This can be due to the increased exposure of dough to HCA, which had reduced the water absorption and resulted in less moisture content in the final product. The acidity of dough can change the mixing behaviour and results in a significant decrease in water absorption (Koceva et al., 2010). However, there was no significant difference among the breads on the moisture content (varied from 29.9% to 31.6%). The ash content refers to the mineral content of the bread samples and almost similar (statistically insignificant) ash content was observed in all the bread samples except bread with WPI encapsulate, which had significantly lower ash content than bread with MD and WPI + MD. 3.5. Evaluation of quality characteristics of bread Bread making is a complex process mainly consists of mixing, fermentation and baking, during which water evaporation, volume expansion, starch gelatinization, protein denaturation and crust formation occurs (Sivam et al., 2010). So, the addition of any extra compounds can influence the baking process and results in qualitative changes in the bread. The volume of bread samples were depicted in Table 1. During mixing, air is incorporates in the form of small nuclei/cells into the dough (MacRitchie, 1976). These gas cells expand during proofing and baking with increase in temperature (He and Hoseney, 1991). During the later stages of baking, cross linking of proteins along with gelatinization of starch leads to a rupture in the cell wall, allows the gas to escape from crumb to crust (Bloksma, 1981). Garcinia water extract incorporated bread had considerably

lower volume than microencapsules incorporated breads. Acids can lower internal pH in dough, prevent normal yeast growth (leavening agent) (Peres et al., 2005) affect the effective dough development. Other reason for the cessation of dough expansion during baking is the resistance of dough to extension (Zhang et al., 2007). Acid addition to wheat dough has been reported to decrease extensibility (Tanaka et al., 1967). Hence the flattening occurred in the baked loaf due to lack of strength and tenacity of dough and resulted in poor bread volume in Garcinia water extract incorporated bread. However encapsulation of Garcinia extract with wall materials has partially protected the dough from the effect of acid (HCA) and helped to retain their volume to certain level. Comparatively bread with WPI encapsulates had significantly higher volume than WPI + MD and MD breads indicating its effective encapsulation. The same trend was observed in crumb firmness (hardness) of bread samples (Table 1). During bread making, water moves from hydrated gluten to starch granules and causes gelatinization. Interactions occur between gelatinized starch granules and the gluten network in the crumb region, leads to loss of kinetic energy and subsequently results in bread firmness (Ottenhof and Farhat, 2004). The degree of gelatinization depends on the available water and temperature during baking (Blanshard, 1987). Microencapsulates incorporated breads had significantly lower crumb firmness than water extract incorporated bread due to encapsulation, which had protected the crumb texture from the effect of acid (HCA). Comparatively, bread with WPI encapsulates had slightly (statistically insignificant) lower firmness value due to reduced exposure of bread to Garcinia extract. Moreover, the crumb firmness decreased as the moisture content increased (see Table 1). The moisture content of the crumb have some mechanical and qualitative implications, in relation with the gelatinization of starch in the dough during baking process and correlates with crumb softness (Zghal et al., 2002). Water also plays an important role in crumb firmness due to its plasticizing effect on the crumb network (Hugiten et al., 2003). The colour values such as L (luminosity), a (redness versus green), b (yellowness versus blue) and DE (total colour difference) of the crumb of bread samples were depicted in Table 1. The colour of bread was related to physico-chemical characteristics of raw dough and chemical reactions (Maillard reactions and caramelization) during baking that produced browning (Tong et al., 2010). Temperature of crumb portion is much lower than crust, but water activity is high, that causes light colouration (Borrelli et al., 2003). The results clearly showed that microencapsulates incorporated bread samples had significantly higher L value, lower a, b and DE value than water extract incorporated bread. This was due to the encapsulation that reduced the exposure of bread to Garcinia extract (visually brown in colour). Comparatively bread with WPI encapsulates had significantly higher L value, lower a and DE value than the other two encapsulates incorporated bread indicating

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Table 2 Effect of incorporation of freeze dried microcapsules of Garcinia cowa extract on sensory quality of bread. Bread samples

Crust colour (10)

Shape (10)

Crumb colour (10)

Taste (10)

Texture (15)

Grain (15)

Overall sensory score (70)

Control Extract WPI MD WPI + MD

8.5 ± 2.90 7 ± 0.8 8.1 ± 1.3 8.5 ± 1.58 8.1 ± 0.89

10 ± 0.94 9.1 ± 1.4 10 ± 0 9.7 ± 0.94 9.7 ± 0.94

9.7 ± 0.94 5.3 ± 1.23 7.5 ± 1.52 6.1 ± 1.47 6.1 ± 0.98

9.7 ± 1.26 4.6 ± 2.49 7.2 ± 1.32 7.9 ± 1.44 7.2 ± 1.63

14.2 ± 1.26 10.4 ± 1.68 13.5 ± 1.48 12.8 ± 1.58 12.8 ± 1.58

14.1 ± 4.08 8.5 ± 6.71 11.9 ± 1.46 10.6 ± 1.68 10.6 ± 1.68

66.2 ± 4.08 44.9 ± 6.71 58.2 ± 5.22 55.6 ± 4.64 54.5 ± 4.91

The scores are means ± SD of 10 panelist.

its effective encapsulation of Garcinia extract. The scores of sensory evaluation also supported this result (Table 2). The average scores for sensory attributes of the bread samples are depicted in Table 2. The microencapsulates incorporated breads had significantly higher sensory scores than water extract incorporated bread due to enhanced crust colour, shape, symmetry, crumb colour, taste, texture and grain. The lower sensory score of water extract incorporated bread can be due to increased sour taste, poor crust and crumb colour and lower grain scores. These sensory attributes were imparted by direct exposure of HCA on bread quality. The addition of phenolic compounds in food formulations may lead to negative effects on the sensory attributes of finished foods such as increase in bitterness and astringency (Jaeger et al., 2009). The microencapsulation of Garcinia fruit extract had prevented the exposure of bread to undesirable sensory attributes of the phenolic compounds (HCA) and resulted in higher sensory scores. Comparatively, bread with WPI encapsulates had higher overall sensory score exhibiting its better encapsulation of Garcinia extract than other wall materials, but without any significant difference. Microencapsulates incorporated breads had significantly enhanced qualitative characteristics such as volume, crumb texture, colour and sensory attributes than the water extract incorporated bread. This is due to the encapsulation of Garcinia extract with wall materials, which had protected the dough from effect of acid (HCA) and helped to retain the qualitative characteristics of breads to certain level. But the encapsulation had offered only a partial protection to bread due to the porous structures of freeze dried particles. The porous structures exposed the inner part of particles to an outside atmosphere and retarded the complete protection of bread from the exposure of HCA. Anwar and Kunz (2011) also reported the oxidative stability of freeze dried encapsulated fish oil to be reduced due to the porous structure of the particles. Comparatively bread with WPI encapsulates exhibited better qualitative characteristics indicating its effective encapsulation of the Garcinia fruit extract. This may be due to the denaturation of WPI during bread baking. Heating of whey protein can causes protein denaturation and exposure of internal sulfhydryl groups, promoting intermolecular disulphide bond formation (Shimada and Cheftel, 1989). The unfolded structure and covalent disulphide bonding produces stronger, water insoluble and aggregated gel network that can withstand greater de-formations (Bryant and McClements, 1998). Published literature indicates that degree of denaturation of proteins increases with increasing temperature and holding time (Anandharamakrishnan et al., 2008). Despite the porous structure of the particles, encapsulation with WPI had reduced the exposure of bread to HCA through stronger gel network. 3.6. HCA content in bread samples The free HCA concentrations of water extract and microencapsulates incorporated breads is depicted in Table 1. The results clearly shows that bread with WPI encapsulates had significantly higher free HCA content than bread with MD and WPI + MD

encapsulates. This may be due to denaturation of whey protein during bread baking that formed stronger and aggregated network over the Garcinia fruit extract and may efficiently prevented the exposure of HCA to high temperature as indicated earlier. Consequentially, it decreased the conversion of free HCA to lactone HCA and resulted in higher free HCA retention. The kinetics of bioactive compound degradation from dehydrated materials is strongly dependent on dried matrix structure (Madene et al., 2006). On comparing the HCA retention in breads with encapsulated powders, it was observed that all the three wall materials could yield higher free and net HCA recovery (above 85%) on encapsulation using freeze drying technique. But on incorporation in bread only WPI could effectively encapsulate and protect the retained HCA from thermal degradation during baking in spite of the porous structure of particles. This indicates the excellent encapsulation efficiency of WPI during bread baking. HCA has been reported to be a potential anti-obesity agent. From various studies, it is clear that, HCA concentration of about 1200–2800 mg/day can be effective in weight management and divided daily doses are significantly more effective than single daily doses (Ramos et al., 1995; Preuss et al., 2005). The amount of free HCA present in 100 g of breads was 525 mg, 484 mg and 487 mg in WPI, MD, WPI + MD encapsulates incorporated bread respectively (Given in Table 1), which may be sufficient to claim for functionality of HCA incorporated in bread. Hence, 10–15 slices (28 g/slice) of these breads can be consumed per day to get 1300–2200 mg of HCA, that may be sufficient to impart health benefits within the safety limit of the HCA of about 2800 mg/day (Soni et al., 2004). Numerous animal studies (Greenwood et al., 1981; Roy et al., 2004) and human studies (Ramos et al., 1995; Preuss et al., 2005) had reported significant weight loss due to HCA intake along with the improved blood lipid levels (Preuss et al., 2004 Thom, 1996). In few studies, HCA reported insignificant weight loss due to administration of HCA with high fibre rich diet and low calorie diet (Heymsfield et al., 1998) which reduced the bioavailability and negated the utility of HCA respectively. Moreover, low dosage of HCA, short duration of the study (Kovacs et al., 2001), poor patient compliance and differences in the compositional characteristics of the Garcinia extract influenced the bioavailability of HCA (Heymsfield et al., 1998; Soni et al., 2004).

4. Conclusion This study clearly indicated that freeze drying had efficiently encapsulated Garcinia fruit extract with higher encapsulation efficiency (above 90%) using all the three encapsulating wall materials. Microencapsulates incorporated breads had significantly enhanced qualitative characteristics than the water extract incorporated bread. Comparatively, bread with WPI encapsulates exhibited significantly higher volume, softer crumb texture, highly desirable sensory attributes due to its efficient encapsulation. Furthermore, WPI efficiently encapsulated and well protected the retained HCA in bread, during baking and resulted in higher HCA

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retention. The results of qualitative characteristics of bread sample were consistent with HCA retention indicating WPI has excellent encapsulation efficiency than other two wall materials during bread baking. Acknowledgement The author (Ezhilarasi) thanks the University Grants Commission (UGC) for awarding JRF fellowship. Appendix A. Supplementary material Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.jfoodeng.2013. 01.009. References AACC, 2000. Approved Methods of American Association of Cereal Chemist, eighth ed. Approved Methods Nr. 44-16, 08-01,10-05, 74-09. St Paul, Minnesota, USA. Anandharamakrishnan, C., Rielly, C.D., Stapley, A.G.F., 2008. Loss of solubility of alactalbumin and ß-lactoglobulin during the spray drying of whey proteins. LWT – Food Science and Technology 41 (2), 270–277. Anandharamakrishnan, C., Rielly, C.D., Stapley, A.G.F., 2010. Spray-freeze-drying of whey proteins at sub-atmospheric pressures. Dairy Science and Technology 90 (2–3), 321–334. Anwar, S.H., Kunz, B., 2011. The influence of drying methods on the stabilization of fish oil microcapsules: comparison of spray granulation, spray drying, and freeze drying. Journal of Food Engineering 105 (2), 367–378. Avaltroni, F., Bouquerand, P.E., Normand, V., 2004. Maltodextrin molecular weight distribution influence on the glass transition temperature and viscosity in aqueous solutions. Carbohydrate Polymers 58 (3), 323–324. Blanshard, J.M.V., 1987. Starch granule structure and function: a physicochemical approach. In: Gallidard, T. (Ed.), Starch: Properties and Potential. John Wiley & Sons, Chichester, New York, pp. 16–54. Bloksma, A.H., 1981. Effect of surface tension in the gas-dough interface on the rheological behavior of dough. Cereal Chemistry 58 (6), 481–486. Borchani, C., Besbes, S., Masmoudi, M., Blecker, C., Paquot, M., Attia, H., 2011. Effect of drying methods on physico-chemical and antioxidant properties of date fibre concentrates. Food Chemistry 125 (4), 1194–1201. Borrelli, R.C., Mennella, C., Barba, F., Russo, M., Russo, G.L., Krome, K., Erbersdobler, H.F., Faist, V., Fogliano, V., 2003. Characterization of coloured compounds obtained by enzymatic extraction of bakery products. Food and Chemical Toxicology 41 (10), 1367–1374. Bryant, C.M., McClements, D.J., 1998. Molecular basis of protein functionality with special consideration of cold-set gels derived from heat-denatured whey. Trends in Food Science and Technology 9 (4), 143–151. Champagne, C.P., Fustier, P., 2007. Microencapsulation for the improved delivery of bioactive compounds into foods. Current Opinion in Biotechnology 18 (2), 184– 190. Chen, C., Chi, Y.-J., Xu, W., 2011. Comparisons on the functional properties and antioxidant activity of spray-dried and freeze-dried egg white protein hydrolysate. Food and Bioprocess Technology. http://dx.doi.org/10.1007/ s11947-011-0606-7. Clouatre, D., Rosenbaum, M., 1994. The Diet and Health Benefits of HCA Hydroxycitric Acid: A Keats Good Health Guide. Keats Publishing, New Cannan, CT, p. 9. Craig, D.Q.M., Royall, P.G., Kett, V.L., Hopton, M.L., 1999. Relevance of the amorphous state to pharmaceutical dosage forms: glassy drugs and freeze dried systems. International Journal of Pharmaceutics 179 (2), 179–207. Desai, K.G.H., Park, H.J., 2005. Recent developments in microencapsulation of food ingredients. Drying Technology 23 (7), 1361–1394. Dolinsky, A., Maletskaya, K., Snezhkin, Y., 2000. Fruit and vegetable powders production technology on the bases of spray and convective drying methods. Drying Technology 18 (3), 747–758. Downton, G.E., Flores-Luna, J.L., King, C.J., 1982. Mechanism of stickiness in hygroscopic amorphous powders. Industrial and Engineering Chemistry Fundamentals 21 (4), 447–451. Fissore, D., Pisano, R., Barresi, A.A., 2010. Monitoring of the secondary drying in freeze-drying of pharmaceuticals. Journal of Pharmaceutical Science 100 (2), 732–742. Franks, F., Hatley, R.H.M., 1991. Stability of proteins at subzero temperatures: thermodynamics and some ecological consequences. Pure Applied Chemistry 63 (10), 1367–1380. Goula, A.M., Adamopoulos, K.G., 2008. Effect of maltodextrin addition during spray drying of tomato pulp in dehumidified air: I. Drying kinetics and product recovery. Drying Technology 26 (6), 714–725. Goula, A.M., Adamopoulos, K.G., 2010. A new technique for spray drying orange juice concentrate. Innovative Food Science and Emerging Technologies 11 (2), 342–351.

519

Greenwood, M.R., Cleary, M.P., Gruen, R., Blase, D., Stern, J.S., Triscari, J., Sullivan, A.C., 1981. Effect of ()-hydroxycitrate on development of obesity in the Zucker obese rat. American Journal of Physiology 240 (1), E72–E78. Harnkarnsujarita, N., Charoenrein, S., Roos, Y.H., 2012. Microstructure formation of maltodextrin and sugar matrices in freeze-dried systems. Carbohydrate Polymers 88 (2), 734–742. Hayamizu, K., Hirakawa, H., Oikawa, D., Nakanishi, T., Takagi, T., Tachibana, T., Furuse, M., 2003. Effect of Garcinia cambogia extract on serum leptin and insulin in mice. Fitoterapia 74 (3), 267–273. He, H., Hoseney, R.C., 1991. Gas retention in bread dough during baking. Cereal Chemistry 68, 521–525. Heymsfield, S.B., Allison, D.B., Vasselli, J.R., Pietobelli, D.G., Nunthe, C., 1998. Garcinia cambogia (hydroxycitric acid) as a potential antiobesity agent. A randomized control trial. Journal of American Medical Association 280 (18), 1596–1600. Hugiten, Escher F., Conde-Petit, B., 2003. Staling of bread: role of amylose and amylopectin and influence of starch degrading enzymes. Cereal Chemistry 80 (6), 654–661. Indrani, D., Prabhasankar, P., Rajiv, J., Rao, V.G., 2003. Scanning electron microscopy, rheological characteristics, and bread- baking performance of wheat flour dough as affected by enzymes. Journal of Food Science 68 (9), 2804–2809. Jaeger, S.R., Axten, L.G., Wohlers, M.W., Sun-Waterhouse, D., 2009. Polyphenol-rich beverages: insights from sensory and consumer science. Journal of the Science of Food and Agriculture 89 (14), 2356–2363. Jayaprakasha, G.K., Sakariah, K.K., 2000. Determination of ()-hydroxycitric acid in commercial samples of Garcinia cambogia extracts by liquid chromatography using ultraviolet detection. Journal of Liquid Chromatography and Related Technologies 23 (6), 915–923. Jena, B.S., Jayaprakasha, G.K., Sakariah, K.K., 2002a. Organic acids from leaves, fruits and rinds of Garcinia cowa. Journal of Agricultural and Food Chemistry 50 (12), 3431–3434. Jena, B.S., Jayaprakasha, G.K., Singh, R.P., Sakariah, K.K., 2002b. Chemistry and biochemistry of ()-hydroxycitric acid from Garcinia. Journal of Agricultural Food Chemistry 50 (1), 10–22. Kent-Jones, D.W., Amos, O.B.E., 1967. Modern Cereal Chemistry. Food Trade Press Ltd., London. Kilburn, D., Claude, J., Schweizer, T., Alam, A., Ubbink, J., 2005. Carbohydrate polymers in amorphous states: an integrated thermodynamic and nanostructural investigation. Biomacromolecules 6 (2), 864–879. Koceva, K.D., Ugarcic-Hardi, Z., Jukic, M., Planinic, M., Bucic-Kojic, A., Strelec, I., 2010. Wheat dough rheology and bread quality affected by Lactobacillus brevis preferment, dry sourdough and lactic acid addition. International Journal of Food Science and Technology 45 (7), 1417–1425. Kovacs, E.M.R., Westerterp-Plantenga, M.S., 2006. Effects of ()-hydroxycitrate on net fat synthesis as de novo lipogenesis. Physiology & Behavior 88 (4–5), 371– 381. Kovacs, E.M., Westerterp-Plantenga, M.S., De Vries, M., Brouns, F., Saris, W.H., 2001. Effects of 2-week ingestion of ()-hydroxycitrate and ()-hydroxycitrate combined with medium chain-triglycerides on satiety and food intake. Physiology and Behaviour 74 (4–5), 543–549. Krishanmurthy, N., Lewis, Y.S., Ravindranath, B., 1982. Chemical constituents of kokum fruit rind. Journal of Food Science and Technology 19 (3), 97–100. Lin, L., Lei, F., Sun, D.-W., Dong, Y., Yang, B., Zhao, M., 2012. Thermal inactivation kinetics of Rabdosia serra (Maxim.) Hara leaf peroxidase and polyphenol oxidase and comparative evaluation of drying methods on leaf phenolic profile and bioactivities. Food Chemistry 134 (4), 2021–2029. MacRitchie, F., 1976. The liquid phase of dough and its role in baking. Cereal Chemistry 53 (3), 318–326. Madene, A., Jacquot, M., Scher, J., Desobry, S., 2006. Flavour encapsulation and controlled release—a review. International Journal of Food Science and Technology 41 (1), 1–21. Mascarenhas, W.J., Akay, H.U., Pikal, M.J., 1997. A computational model for finite element analysis of the freeze drying process. Computer Methods in Applied Mechanics and Engineering 148 (1–2), 105–124. Meza, B.E., Verdini, R.A., Rubiolo, A.C., 2010. Effect of freezing on the viscoelastic behaviour of whey protein concentrate suspensions. Food Hydrocolloids 24 (4), 414–423. Mondal, A., Datta, A.K., 2008. Bread baking—a review. Journal of Food Engineering 86 (4), 465–474. Ottenhof, M.A., Farhat, I.A., 2004. The effect of gluten on the retrogradation of wheat starch. Journal of Cereal Science 40 (3), 269–274. Peres, M.F.S., Tininis, C.R.C.S., Souza, C.S., Walker, G.M., Laluce, C., 2005. Physiological responses of pressed baker’s yeast cells pre-treated with citric, malic and succinic acids. World Journal of Microbiology and Biotechnology 21 (4), 537–543. Perez-Alonso, C., Fabela-Moron, M.F., Guadarrama-LezamA, Y., Barrera-Pichardo, J.F., Alamilla-Beltran, L., Rodriguez-Huezo, M.E., 2009. Interrelationship between the structural features and rehydration properties of spray dried manzano chilli sauce microcapsules. Revista Mexicana de Ingenieria Quimica 8 (2), 187–196. Pierce, M.M., Walker, C.E., 1987. Addition of sucrose fatty acid ester emulsifiers to sponge cakes. Cereal Chemistry 64 (4), 222–225. Pikal, M.J., Rambhatla, S., Ramot, R., 2002. The impact of freezing stage in lyophilization: effect of the ice nucleation temperature on process design and product quality. American Pharmaceutical Review 5 (4), 48–53. Pillai, D.S., Prabhasankar, P., Jena, B.S., Anandharamakrishnan, C., 2012. Microencapsulation of Garcinia cowa fruit extract and effect of its use on

520

P.N. Ezhilarasi et al. / Journal of Food Engineering 117 (2013) 513–520

pasta process and quality. International Journal of Food Properties 15 (3), 590– 604. Preuss, H., Bagchi, D., Bagchi, M., Rao, C., Satayanarayana, S., 2004. Efficacy of a novel, natural extract of ()-hydroxycitric acid (HCA-SX) and a combination of HCA-SX, niacine-bound chromium and Gymnesa sylvestre extract in weight management in human volunteers. Nutrition Research 24 (1), 45–58. Preuss, H., Garis, R., Bramble, J., Bagchi, D., Bagchi, M., Rao, C., Satyanarayana, S., 2005. Efficacy of a novel calcium/potassium salt of ()-hydroxycitric acid in weight control. International Journal of Clinical Pharmacology Research 25 (3), 133–144. Ramos, R.R., Saenz, J.L., Aguilar, C.F., 1995. Extract of Garcinia cambogia in controlling obesity. Investigacion Medica Internacional 22, 97–100. Roy, S., Rink, C., Khanna, S., Phillips, C., Bagchi, D., Bagchi, M., Sen, C.K., 2004. Body weight and abdominal fat gene expression profile in response to a novel hydroxycitric acid-based dietary supplement. Gene Expression 11 (5–6), 251– 262. Sanchez, V., Baeza, R., Galmarini, M.V., Zamora, M.C., Chirife, 2011. Encapsulation of red wine polyphenols in an amorphous matrix of maltodextrin. Food and Bioprocess Technology. http://dx.doi.org/10.1007/s11947-011-0654. Shahidi, F., Han, X.Q., 1993. Encapsulation of food ingredients. Critical Review in Food Science and Nutrition 33 (6), 501–547. Shimada, K., Cheftel, J.C., 1989. Sulfhydryl group disulfide bond interchange during heat induced gelation of whey protein isolate. Journal of Agricultural Food Chemistry 37 (1), 161–168. Sivam, A.S., Sun-Waterhouse, D., Quek, S.Y., Perera, C.O., 2010. Properties of bread dough with added fiber polysaccharides and phenolic antioxidants: a review. Journal of Food Science 75 (8), R163–R174. Soni, M.G., Burdock, G.A., Preuss, H.G., Stohs, S.J., Ohia, S.E., Bagchi, D., 2004. Safety assessment of ()-hydroxycitric acid and Super CitriMax, a novel calcium/ potassium salt. Food and Chemical Toxicology 42 (9), 1513–1529.

Sullivan, A.C., Triscari, J., Spiegel, H.E., 1977. Metabolic regulation as a control for lipid disorders. II. Influence of ()-hydroxycitrate on genetically and experimentally induced hypertriglyceridemia in the rat. The American Journal of Clinical Nutrition 30 (5), 777–784. Tanaka, K., Furukawa, K., Matsumot, H., 1967. Effect of acid and salt on farinogram and extensigram of dough. Cereal Chemistry 44 (6), 675–679. Thom, E., 1996. Hydroxycitrate (HCA) in the treatment of obesity. International Journal of Obesity Related Metabolic Disorders 20 (4), 75. Thorvaldsson, K., Janestad, H., 1999. A model for simultaneous heat, water and vapor diffusion. Journal of Food Engineering 40 (3), 167–172. Tong, Q., Zhang, X., Wu, F., Tong, J., Zhang, P., Zhang, J., 2010. Effect of honey powder on dough rheology and bread quality. Food Research International 43 (9), 2284– 2288. You-Jin, J., Vasanthan, T., Temelli, F., Song, B.-K., 2003. The suitability of barley and corn starches in their native and chemically modified forms for volatile meat flavor encapsulation. Food Research International 36 (4), 349–355. Young, S.L., Salda, X., Rosenberg, M., 1993. Microencapsulating properties of whey proteins. 1. Microencapsulation of anhydrous milk fat. Journal of Dairy Science 76 (10), 2868–2877. Zghal, M.C., Scanlon, M.G., Sapirstein, H.D., 2002. Cellular structure of bread crumb and its influence on mechanical properties. Journal of Cereal Chemistry 36 (2), 167–176. Zhang, L., Lucas, T., Doursat, C., Flick, D., Wagner, M., 2007. Effects of crust constraints on bread expansion and CO2 release. Journal of Food Engineering 80 (4), 1302–1311. Zubair, M., Nybom, H., Lindholm, C., Rumpunen, K., 2011. Major polyphenols in aerial organs of greater plantain (Plantago major L.), and effects of drying temperature on polyphenol contents in the leaves. Scientia Horticulturae 128 (4), 523–529.