The effect of low oxygen and high carbon dioxide on storage and pickle production of pickling cucumbers cv. ‘Octobus’

Journal of Food Engineering 78 (2007) 1034–1046 www.elsevier.com/locate/jfoodeng

The effect of low oxygen and high carbon dioxide on storage and pickle production of pickling cucumbers cv. ‘Octobus’ Bulent Akbudak b

a,*

, Mecit Hakan Ozer a, Vildan Uylaser b, Bige Karaman

b

a Department of Horticulture, Faculty of Agriculture, University of Uludag, Gorukle Campus, 16059 Bursa, Turkey Department of Food Engineering, Faculty of Agriculture, University of Uludag, Gorukle Campus, 16059 Bursa, Turkey

Received 24 September 2005; accepted 21 December 2005 Available online 23 February 2006

Abstract This study was carried out with the aim of determining the optimum storage time and conditions that provide raw material suitable to pickle production. Fresh pickling cucumbers (cv. Octobus) were stored for 30 days at 7 C and 90–95% relative humidity (RH) under different controlled atmosphere (CA) combinations. Samples taken at the beginning and on the 0 (i.e., without storage), 10, 20 and 30 days of storage were processed to sweet pickle. At each sampling, physical and chemical analyses were carried out in the fresh pickling cucumbers to determine the changes in the quality with storage time. Besides, physical, chemical and sensory analyses were carried out in the pickles elaborated from the fresh samples taken at the same periods, after keeping at room temperature for 6 months, with the aim of determining CA and storage time effect on the final pickle quality. It was found that storage of cucumbers to be processed to pickle could be possible for less than 10 days at 7 C temperature and 90–95 RH under normal atmosphere (NA). However, physical and chemical analyses showed that storage period of fresh pickling cucumbers could be prolonged up to 30 days under the same storage conditions, if suitable atmosphere combinations are created. Nevertheless, it was concluded that restricting the storage period of fresh pickling cucumbers to 20 days could give better results after processing to pickle.  2006 Elsevier Ltd. All rights reserved. Keywords: Controlled atmosphere storage; Pickle production; Pickling cucumber; Quality measurements

1. Introduction In recent years, significant increases are being observed in the pickling cucumber exportation of our country. As a matter of fact, our pickling cucumber exportation which was 4 207 511 kg in the year 2000 raised to 8 004 675 kg 2001 and to 85 210 799 kg in 2003. This situation was reflected to the revenue obtained from pickling cucumber exportation as well, and 1 956 670, 3 302 247 and 51 562 791$ of exportation was made in 2000, 2001 and 2003, respectively (Anonymous, 2004). Cucumber is the leading one among the vegetables used in pickle production in the world. The healthiest and most *

Corresponding author. Tel.: +90 224 442 89 70; fax: +90 224 4429098. E-mail address: [email protected] (B. Akbudak).

0260-8774/$ - see front matter  2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.jfoodeng.2005.12.045

proper method is processing the pickling cucumbers immediately after harvest. However, this may not always be possible, since the product coming in high quantities exceeding the capacity of the plant within a short time makes the storage compulsory. Pickling cucumbers are generally stored in the brine for long-term storage. However, fresh pickling cucumbers should be precooled to 10 C as fast as possible in the situations in which they should be stored for a short time before storage or processing or being placed into the brine tank (Anonymous, 2001). Holmes (2000) reported that fresh cucumbers should be kept at 7.2–10 C and should be transported as fast as possible, if they are going to be shipped to distant markets. It was reported in another group of studies on the storage of pickling cucumbers that storage at 4–4.5 C for 1 week could be convenient (Fellers

B. Akbudak et al. / Journal of Food Engineering 78 (2007) 1034–1046

& Pflug, 1967; Hardenburg, Watada, & Wang, 1986). It was determined as the result of a study aimed at determining the suitable storage temperatures and storage periods of the pickling cucumber cultivars ‘Opera’, ‘Ajax’, ‘Troy’ and ‘Octobus’ that the optimum storage temperature for pickling cucumbers could range from 4 C to 10 C, in accordance with the studies above. In the study, it was determined that fruits of the cvs ‘Octobus’, ‘Troy’ and ‘Opera’ could be stored successfully at 4 C or 7 C, while those of cv. ‘Ajax’ at 10 C (Akbudak & Ozer, 2003). It was determined in a study in which the rates O2, CO2 and temperature combinations were examined with the aim of prolonging the storage period of pickling cucumbers that the spoilage could be inhibited for one week in NA, 2 weeks in 5–10% CO2 + 3% O2, 3 weeks in 15% CO2 + 3% O2 and 5 weeks in 20–30% CO2 regardless of O2 level. Moreover, no spoilage was observed at the end of one week in NA at 4 C, one week in 20% CO2 + 3% O2 and 4 weeks at 4 C. Although spoilage could be controlled for a few weeks in controlled atmosphere (CA), storage should not exceed 2 weeks (Buescher, 1987). Suitable conditions are recommended as 2–3 weeks in 3–5% CO2 + 3–5% O2 similarly in the other studies carried out on CA storage (Saltveit, 2001; Salunkhe & Desai, 1984). Another common opinion in the studies is the benefit of water precooling for the pickling cucumbers harvested in hot air (Salunkhe & Desai, 1984). However, pickling cucumbers should not have been stored for more than a few days before processing if they are precooled by water, since washing reduces their storage life to half. For this reason, unwashed fruits maintain acceptable quality for 6 days at 4–5 C, while this period was less than 4 days in washed fruits (Fellers & Pflug, 1967). If the pickling cucumbers are to be processed just after cold storage, this period can be prolonged by cooling and keeping at 1–2 C, without symptoms of chilling injury (Ryall & Lipton, 1979; Saltveit, 2001). Nevertheless, use of water colder than 6 C in precooling or cooling the cucumbers are not recommended since these practices increase the risk of chilling injury (De Ell, Vigneault, & Lemerre, 2000). Spotting, spoilage, weight loss (Purvis, 1996), electrolyte leakage, chlorophyll fluorescence and respiration rates (Hakim, Purvic, & Mullinix, 2000) were noted as the symptoms induced by chilling and physiological disorders, in a study on susceptibility to chilling. Production of sweet pickles is also in question nearby the production of classical sour pickles with vinegar in the case of processing the cucumbers to pickle. The differences of sweet pickle which is mostly produced for exportation in our country from the classical method are the addition of sugar to its composition at different rates during the preparation of brine, use of some drugs for balancing the sweet taste caused by sugar and omission of fermentation process. The sugar quantity in sweet pickle production changes between 12% and 22% depending on the demand. Moreover, black pepper seed, mustard seed, onion, thyme, etc. are added to the brine with the aim of

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aromatizing and balancing the taste of sugar (Binsted, Devey, & Dakın, 1962; Uylaser & Erdem, 2004). The leading one among our important products with respect to commercial value and consumption is primarily dependent on the crude material which did not lose its characteristics. In this study the effect of CA storage of cucumbers realized with the aim of minimizing the postharvest quality loss-in the situations in which the processing of harvested cucumbers to pickle immediately was not possible or when the product coming to the factory exceeds the production capacity-on the final product quality was investigated. Moreover, the determination of optimum storage period and conditions for the raw material suitable to pickle production and transferring of the information obtained to the industry increases the importance of the study. 2. Materials and methods 2.1. Test material The study was carried out between the Controlled Atmosphere-Cold Storage Research and Application Facility of Department of Horticulture and Laboratory for Fruit-Vegetable Processing Technology at the Department of Food Engineering, Uludag University. Fruits of cucumber cv. ‘Octobus’ were supplied from the garden of a grower who conducted contracted farming on the behalf of a big company in our country located in Odemis country of Manisa province in the Aegean region. Pickling cucumbers were hand-harvested in June when they reached a length of approximately 5 cm (Salunkhe & Desai, 1984). Harvested cucumbers were placed into the plastic boxes with 5 kg capacity and taken into the cold store with a frigorific vehicle. 2.2. Storage of fresh pickling cucumbers in CA Pickling cucumbers which were brought into the cold store were sorted depending on their colour and length and suitable ones were selected thereafter, they were put into plastic containers with 500 g capacity after which they were placed into the plastic cold chambers with 120 L volume in which the inner atmosphere combinations could be controlled. In the study, totally 200 kg of pickling cucumbers cv. ‘Octobus’ were used in 10 plastic containers, being 20 kg of fruit in each replicate. Pickling cucumbers were stored at 7 C temperature and 90–95% RH (Akbudak & Ozer, 2003; Holmes, 2000) and under different atmosphere combinations (0% CO2 + 21% O2-NA; 10 + 3; 20 + 3; 10 + 5; 5 + 10). Atmosphere combinations were established considering the values recommended in the studies carried out on the CA storage of pickling cucumbers and the values close to them (Buescher, 1987; Saltveit, 2001; Salunkhe & Desai, 1984). Atmosphere combinations in plastic containers could be controlled by using ‘BBG Goerz Metrowatt’ recorder,

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‘Servomex 1420’ O2 analyzer and ‘Servomex 1410’ CO2 analyzer. Atmosphere combinations were maintained through semi-automatic gas addition and/or full automatic CO2 scrubbers (activated charcoal), in case of a change monitored in atmospheric combinations in the plastic containers depending on the results of continuous measurements and records realized by O2 and CO2 analyzers. Changes in O2 and CO2 rates in each plastic container was controlled at the deviation level of not more than 0.1–0.2%. 2.3. Physical and chemical analyses carried out during the CA storage of fresh pickling cucumbers 2.3.1. Weight loss Weight losses, which occurred in fruits during storage, were detected using precision balance (0.01 g precision), considering former weight value in each analytical period. 2.3.2. Respiration rate Changes in the respiration rate of fruits within the period beginning with the harvest date till the end of storage were determined as mgCO2 kg 1 h 1 using the Claypool and Keefer (1942) method depending on CO2 absorption basis. Respiration rate measurements were realized under unheated laboratory conditions at about 10 C. 2.3.3. Fruit flesh firmness Firmness measurements of fruits were read as lb with 0.79 cm probe of FT327 brand penetrometer. Measurements were realized as a single reading in the middle part of the each fruit sampled. 2.3.4. Total soluble solids Fruit samples taken from fresh pickling cucumber fruit were passed through blender in the laboratory and TSS rate of the fruit juice was determined as percent sucrose using N.O.W. refractometers. 2.3.5. Titratable acidity Twenty grams of fruit pulp was taken from fresh pickling cucumbers, and brought to a final volume of 100 mL by adding distilled water. A 20 mL sample was taken from the mixture and 3–4 drops of phenolphthalein was dropped on to the sample. This solution was titrated with 0.1 N NaOH until obtaining pink colour and the results were calculated in terms of lactic acid, the most common acid in fresh pickling cucumbers (Cemeroglu, 1992). 2.3.6. pH pH measurements of fruits were made using NEL 890 brand pH meter. 2.3.7. Total chlorophyll The samples taken from the skin and fruit flesh parts of fresh pickling cucumber were subjected to extraction with acetone (90%); the absorbance values were monitored in

spectrophotometer (Shimadzu VV-120-01) at 652 nm wavelength against distilled water in the filtrate of these extracts, and total chlorophyll was calculated (Holden, 1976). 2.3.8. Overall appearance Changes in the external appearances of fresh pickling cucumbers during storage were evaluated by a jury of five persons (as 10–8 very good, 7–6 good, 5–4 bad, 3–1 unusable). 2.3.9. Fruit skin and fruit flesh colour Skin colours of fresh pickling cucumber were determined by two readings on the two different symmetrical faces of the fruit in each replicate, using Minolta CR-300. Fruit flesh colour was determined via the readings made in the both halves of the fruits cut in the middle using Minolta CR-300. 2.3.10. Ion leakage Cylinders of mesocarp tissue were excised with a 10 mm diameter stainless steel cork borer from the mid-part of five fruit. Mesocarp disks (4 mm thick) were cut from the mid portion of each cylinder with a stainless steel razor blade. Four disks from each treatment were put into 10 mL of aqueous 0.3 mol L 1 mannitol and shaken at 100 cycles per min for 3 h, and then boiled for 5 min. The conductivity of the solution (lS cm 1) was periodically measured with an InoLab-Tetra Con 325 (WTW, Germany) conductivity meter. Ion leakage was calculated as the percentage of the total, boiled value (Lafuente, Belver, Guye, & Saltveit, 1991). 2.4. Sweet pickle production Samples taken from the fruits of cucumber cv. ‘Octobus’ which were stored under different atmosphere conditions (0% CO2 + 21% O2-NA; 10 + 3; 20 + 3; 10 + 5; 5 + 10) at the beginning of storage (0 day) and at three stages with 10-day intervals (10, 20 and 30 days) were processed to pickle, being three replicates. Sweet pickle production was taken as basis in the trial and the brine brix was determined as 11 g 100 1 g 1 (Table 1). The brine was subjected to thermal treatment and vinegar and aroma were added into it when the temperature reached 90 C. Dill (1 g), 1g of cubic onion, 3–4 seeds of yellow mustard and 0.5 g of black pepper seed were added into each jar of 720 mL volume in order to give palatability (Binsted et al., 1962; Uylaser & Erdem, 2004). Control samples of day ‘0’ whose raw material analyses were completed were given priority for pickle production Table 1 Composition of the brine Vinegar Salt Sugar Aroma Water

133 mL L 36 g L 1 60 g L 1 2.5 mL L 857 mL L

1

1 1

B. Akbudak et al. / Journal of Food Engineering 78 (2007) 1034–1046

and they were processed to brine. The cucumbers were washed and stored at first, and thereafter the flower stalks containing high quantities of pectolytical enzymes were removed. The pretreated cucumbers were filled into the jars of 750 mL volume, being 500 g of cucumbers in average in each jar, and the brine with an approximate temperature of 90 C was added onto it. The pickles which were then subjected to air discharge and closed and pasteurized for 27 min at 85 C were cooled gradually. The same practices were carried out in the control samples which were taken 10 days later, however, the control samples were not involved in the production due to excessive weight loss in the control group cucumbers, during the following two periods (20 and 30 days). In a related study, cucumbers are accepted to be softened when they reached the firmness value of 5.46–6.15 kg (12.04–13.56 lb) (Ozcelik, Yıldırım, & Ic, 2001). For this reason, cucumbers belonging to the control group could not be processed to pickle beyond the 10th day. Samples taken from four different storage conditions (10 + 3; 20 + 3; 10 + 5; 5 + 10) other than control were processed to pickle as described above with 10-day intervals; the pickles were stored at shelf-life conditions (20 ± 2 C and 60 ± 5%RH) 60 for 6 months and subjected to physical, chemicals analyses and sensory evaluation with the same time intervals.

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FW) and fruit fresh firmness (FFF) (kg) were conducted in the samples taken with the same time intervals 6 months after the processing of the samples taken in three 10-day periods at the beginning of storage and during storage at different conditions, to brine. On the other hand, Altug (1993) was taken as basis in the sensory evaluation (appearance, colour, fragrance, taste and firmness) realized with the same samples and the scoring system was applied after modification. In the scoring system, the numbers were interpreted as follows: 10: extra ordinary, 9: excellent, 8: very good, 7: good, 6: above average, 5: average, 4: below average, 3: limit, 2: bad-defected, 1: very bad, 0: inconsumable. The analyses were carried out so that there would be three parallels in each replicate. Panelists carried out the sensory analyses were academic personnel of food engineering department and they were trained about the evaluation criteria of pickles. 2.5.1. Vacuum determination Vacuum measurement was made using a vacuum-meter. Vacuum quantity of samples was read as mmHg from the indicator and them recorded (Cemeroglu, 1992). 2.5.2. Gross weight Whole weight of preserves including the container weight were weighed on a balance with 0.01 g precision and the gross weight was stated as g (Cemeroglu, 1992).

2.5. Physical, chemical and sensory analyses conducted in the pickle samples

2.5.3. Net weight This determination was made by subtracting the weight of jar content from the gross weight, after being emptied, washed and dried, and expressed as g (Cemeroglu, 1992).

Physical and chemical analyses such as vacuum (mmHg), gross weight (g), net weight (g), space at the top (mm), strained weight (g), dry matter (g 100 1 g 1), TA (%), pH, salt (%), total chlorophyll (mg 100 1 g 1

Table 2 Physical and chemical changes determined during CA storage of fresh pickling cucumbers cv. ‘Octobus’ Storage period (days)

Treatment (CO2%:O2%)

Weight loss (%) a

Respiration rate (mgCO2 kg

1

Firmness (kg)

TSS (%)

TA (%)

pH

Total chlorophyll (mg 100 1 g 1)

Ion leakage (%)

Overall appearance

7.70 a

4.00 fg

0.13 ab

6.47 ef

32.68 a

74.55 g

10.00 a

h 1)

0

0:21

0.00 h

10

0:21 10:3 20:3 10:5 5:10

4.60 1.15 1.15 1.25 1.40

c g g g fg

66.24 64.51 60.22 59.37 59.57

b bc bcd bcd bcd

5.80 7.90 7.40 7.70 7.00

bc a a a ab

5.10 4.65 5.00 4.50 3.90

bcd de cde ef g

0.12 0.12 0.13 0.15 0.13

b b ab ab ab

6.81 6.96 6.98 7.01 7.13

cdef bcdef abcde abcde abcde

17.12 19.51 17.18 16.12 20.23

bcd bc bcd bcd bc

85.85 95.60 95.80 97.50 92.85

f abc ab a bcde

6.00 9.25 9.25 9.50 9.50

d a a a a

20

0:21 10:3 20:3 10:5 5:10

14.75 1.43 1.43 1.52 1.75

b fg fg fg f

63.67 52.73 57.83 58.81 59.64

bc de cd bcd bcd

1.80 7.40 7.30 7.00 6.60

f a a ab abc

4.00 5.90 5.40 5.60 4.70

fg a abc ab de

0.17 0.17 0.15 0.21 0.16

ab ab ab ab ab

7.57 7.32 7.18 7.19 7.23

ab abc abcd abc abc

12.06 18.45 19.73 22.84 16.90

cde bc bc b bcd

98.30 95.55 95.60 96.95 94.30

a abc abc ab abcd

3.50 8.25 7.75 7.50 7.00

e b bc bc c

30

0:21 10:3 20:3 10:5 5:10

25.80 2.35 2.44 2.51 2.90

a e e e d

49.13 30.76 40.39 44.22 45.29

ef h g fg efg

0.30 5.40 5.40 4.00 3.30

g cd cd de e

5.60 5.20 5.00 5.30 5.50

ab bcd cde bc abc

0.12 0.18 0.22 0.20 0.21

b ab a ab ab

7.63 6.30 6.52 6.67 6.68

a f def cdef cdef

6.86 14.40 12.00 12.72 8.94

e bcde cde cde de

91.60 89.30 86.30 91.10 86.95

cde ef f de f

2.00 7.50 6.00 6.00 5.75

f bc d d d

LSD a

0.34

123.95 a

7.23

3.09

0.49

0.08

0.57

7.60

Different letters in the same column indicate significant differences P < 0.05. LSD, least significant difference.

3.63

0.89

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2.5.4. Strained weight The jar content was emptied on to a sieve with 2.8 · 2.8 mm mesh whose tare was determined beforehand and was kept for 10 min for the strained of brine after being spread. Thereafter, strained weight was determined by subtracting the tare of the sieve from the value found by weighing the particles on the sieve expressed as g (Regnell, 1976). 2.5.5. Top space determination The perpendicular distance between the opening edge of the jar and surface of the food in the jar was measured by calipers at five different points and averaged and the result was expressed as mm (Cemeroglu, 1992). 2.5.6. Dry weight Material (5–10 g) was taken from the homogenized samples into the drying containers whose tares were determined beforehand, and kept in the hot air oven at 105 C until it reaches a constant weight. Thereafter, the dry matter quantity in 100 g of sample was calculated gravimetrically (g 100 1 g 1) (Cemeroglu, 1992). 2.5.7. Salt determination Salt was determined by titrating the filtrate prepared for acidity determination with 0.1 N AgNO3 using 5% K2Cr2O7 indicator after being neutralized (Ozgumus, 1999). FFF, TA, pH and total chlorophylls were also determined on the pickle samples as indicated above for the fresh ones. 2.6. Statistical evaluation CA storage trial was established according to A Randomized Plot Factorial Experimental Design with two replicates, consisting of 20 kg of fruit per replicate. The pickle trial was also established in the same experimental design with three replicates, being 1 kg of fruit in each replicate. The results were analyzed using ANOVA and the means were compared using the LSD test (P < 0.05). 3. Results 3.1. Physical and chemical changes determined during CA storage 3.1.1. Weight loss When the weight losses in relation to analytical periods were examined, it was determined that the weight loss ratios increased with the prolonging storage period, however, the highest weight loss ratio was observed in the control group (NA). It was also noted that the differences formed by the NA treatment, compared with CA treatments, either at the time or at the treatments level were significant statistically. At the end of the storage, the highest weight loss ratio was determined in NA, whereas the lowest

values were obtained from CA treatments consisting of 10% CO2 + 3% O2 and 20% CO2 + 3% O2 combinations (Table 2). 3.1.2. Respiration rate Respiration rates of the treatments exhibited a significant reduction on the 10th day of storage—the first analytical period—while these rates generally retained their original values in the later stages. However, the differences between the control group in which the highest respiration rate was obtained at the end of storage (30th day) and the combinations of 10% CO2 + 3% O2 and 20% CO2 + 3% O2 were determined to be significant (Table 2). The lowest respiration rate was obtained from 10% CO2 + 3% O2 treatment, which was followed by 20% CO2 + 3% O2 combination. 3.1.3. Fruit flesh firmness FFF values of treatments were determined to decline with the prolonging storage period, especially with a severe decline on the 20th day of storage in NA treatment. This situation persisted also at the end of the storage, and the lowest FFF value was obtained from the NA treatment. Moreover, the differences determined between NA and CA treatments were determined to be significant statistically (Table 2). 3.1.4. Total soluble solids Increases were determined in TSS values of cucumbers with the prolonging storage period. The highest and the lowest values at the end of storage were taken from the NA treatment and the CA treatment consisting of 20% CO2 + 3% O2, respectively. The difference between these two treatments was found significant statistically (Table 2). 3.1.5. Titratable acidity and pH Changes in the TA values of pickling cucumbers along the storage period were determined to be non-significant both at the time and at the treatments level. Nevertheless, the highest and the lowest TA values at the end of storage were obtained from control and 20% CO2 + 3% O2 treatments, respectively and, only the difference between these two treatments was determined as significant (Table 2). As the pH values of treatments increased on the 20th day of storage, this was followed by the reductions in the treatments other than control. The highest pH value at the end of storage was obtained from the control group in which the lowest TA value was determined CA treatments preserved the pH values at levels close to the initial figures. The differences between the control group and CA treatments were determined to be significant (Table 2). 3.1.6. Total chlorophyll Reductions were observed in total chlorophyll values of pickling cucumbers cv. ‘Octobus’ at different rates with the prolonging storage period. The lowest total chlorophyll values at the end of storage were determined in control and 5% CO2 + 10% O2 treatments (Table 2).

B. Akbudak et al. / Journal of Food Engineering 78 (2007) 1034–1046

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Fig. 1. Changes determined in the fruit skin and flesh colour during the storage of fresh pickling cucumbers cv. ‘Octobus’ under different atmosphere conditions.

3.1.7. Ion leakage When the ion leakage rates of pickling cucumbers were examined, significant increases were noted in all treatments with the prolonging storage period. The highest and the lowest values at the end of storage were obtained from control and 20% CO2 + 3% O2 treatment, respectively. The difference between treatments was determined to be significant (Table 2).

3.1.8. Overall appearance When the treatments are evaluated considering the overall appearance scores, differences began to appear from the 10th day of storage—the first analysis stage—onwards. Differences between NA and CA treatments became more pronounced in the later stages of storage. At the end of the storage, all CA treatments had much higher overall appearance scores compared with NA, at statistically significant

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Table 3 Results of physical analyses related to the pickles manufactured from the cucumber fruits cv. ‘Octobus’ stored in CA for 10 days Storage period (days)

Treatment (CO2%:O2%)

Vacuum (mmHg)

Gross weight (g)

Net weight (g)

Strained weight (g)

0

0:21

87.50 aa

1006.00 a

694.80 a

436.14 c

10

0:21 10:3 20:3 10:5 5:10

50.00 62.50 62.50 50.00 50.00

1003.60 1007.00 1002.80 1003.30 1005.10

692.55 701.23 691.37 691.87 693.93

498.31 508.80 554.38 524.17 477.01

LSD a

a a a a a

30.51

a a a a a

18.29

a a a a a

17.10

Top space (mm) 81.87 a

b ab a ab bc

103.00 96.87 113.25 115.00 88.25

47.28

Firmness (kg) 5.40 a

a a a a a

3.92 5.50 5.40 5.40 5.40

30.75

b a a a a

1.12

Different letters in the same column indicate significant differences P < 0.05. LSD, least significant difference.

Table 4 Results of the physical analyses related to the pickles manufactured from cucumbers cv. ‘Octobus’ stored in CA conditions for 30 days Storage period (days)

Treatment (CO2%:O2%)

Vacuum (mmHg)

Gross weight (g)

Net weight (g)

Strained weight (g)

0

0:21

87.50 aa

1006.00 a

694.80 a

436.14 d

10

10:3 20:3 10:5 5:10

50.00 62.50 62.50 50.00

c b b c

1007.00 1002.80 1003.30 1005.10

a a a a

695.73 691.37 691.87 693.93

a a a a

508.80 554.38 524.17 477.01

bc a ab c

96.87 113.25 115.25 88.25

ab ab ab ab

5.50 5.40 5.40 5.40

a a a a

20

10:3 20:3 10:5 5:10

62.50 62.50 37.50 37.50

b b d d

1004.30 1008.20 1002.20 991.90

a a a a

693.11 696.94 690.36 680.44

a a a a

476.84 500.29 509.84 515.96

c bc bc bc

103.75 97.37 102.62 127.75

ab ab ab a

5.70 5.70 3.80 2.20

a a b c

30

10:3 20:3 10:5 5:10

62.50 62.50 37.50 37.50

b b d d

1003.60 1000.20 1005.80 990.50

a a a a

692.29 689.24 694.54 679.56

a a a a

503.91 bc 509.47 bc 509.61 bc 503.3 bc

96.87 103.62 95.19 119.87

ab ab ab ab

2.70 2.50 0.60 0.20

bc bc d d

LSD a

0.81

18.67

18.81

Top space (mm) 81.87 b

34.25

Firmness (kg) 5.40 a

36.75

2.90

Different letters in the same column indicate significant differences P < 0.05. LSD, least significant difference.

Table 5 Results of the chemical analyses related to the pickles manufactured from cucumbers cv. ‘Octobus’ stored in CA conditions for 10 days Storage period (days)

Treatment (CO2%:O2%)

Dry weight (g 100 1 g 1)

Titratable acidity (g 100 1 mL 1)

pH

0

0:21

8.16 aa

1.23 a

4.20 d

1.41 a

27.91 a

10

0:21 10:3 20:3 10:5 5:10

8.41 8.36 8.25 8.20 8.44

0.88 0.97 0.88 0.88 1.10

4.37 4.44 4.48 4.49 4.30

1.26 1.32 1.27 1.21 1.44

18.07 16.46 17.34 12.62 19.90

LSD a

0.74

a a a a a

b b b b ab

0.20

0.11

Salt (g 100

bc ab ab a cd

a a a a a

0.22

1

mL 1)

Total chlorophyll (g 100 1 g 1)

a a a a a

12.84

Different letters in the same column indicate significant differences P < 0.05. LSD, least significant difference.

level, while the highest score was obtained from the CA treatment consisting of 10% CO2 + 3% O2 (Table 2). 3.1.9. Fruit skin and fruit flesh colour Reductions were observed in the brightness (L) changes of fruit skin and flesh colours during CA storage of pickling cucumbers. This reduction in L values was determined in NA treatment in which the ripening proceeded most rap-

idly with regard to colour values for both two components of this parameter. When the other treatments are examined inter relatedly, one may see that the minimum colour change generally occurred in 10% CO2 + 3% O2 and 20% CO2 + 3% O2 treatments, considering the ‘L’ values. This situation which was observed in ‘L’ values was reflected to the ‘a’ and ‘b’ values. As a matter of fact, reductions and increases were determined in the green colour (a) and

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Table 6 Results of the chemical analyses related to the pickles manufactured from cucumber cv. ‘Octobus’ stored in CA conditions for 30 days Storage period (days)

Treatment (CO2%:O2%)

Dry weight (g 100 1 g 1)

Titratable acidity (g 100 1 mL 1)

pH

0

0:21

8.12 abca

1.23 a

4.20 c

1.41 a

27.91 a

10

10:3 20:3 10:5 5:10

8.37 8.25 8.20 8.44

ab ab ab a

0.97 0.88 0.88 1.10

bc cd cd ab

4.44 4.48 4.49 4.30

ab ab ab bc

1.32 1.27 1.21 1.44

ab abc abc a

16.46 17.34 12.62 19.90

ab ab b ab

20

10:3 20:3 10:5 5:10

8.54 8.28 7.62 7.68

a ab abcd abcd

0.88 0.88 0.83 0.79

cd cd cd d

4.35 4.35 4.43 4.49

bc bc ab ab

1.27 1.21 1.09 1.03

abc abc bc c

16.12 12.29 8.23 17.90

ab b b ab

30

10:3 20:3 10:5 5:10

7.46 7.26 7.03 6.47

bcd cde de e

0.92 0.97 0.97 0.88

cd bc bc cd

4.40 4.42 4.43 4.61

b b ab a

1.27 1.15 1.21 1.15

abc bc abc bc

15.62 14.62 17.62 10.67

ab ab ab b

LSD a

0.80

0.15

0.17

Salt (g 100

0.21

1

mL 1)

Total chlorophyll (g 100 1 g 1)

11.87

Different letters in the same column indicate significant differences P < 0.05. LSD, least significant difference.

yellow colour (b) values of fruits, respectively due to the changes occurred in colour values in relation to the advance in ripening following CA storage of pickling cucumbers. NA treatment had the lowest green colour and the highest yellow colour values with respect to fruit skin and flesh colour. Treatments in which the green colour was maintained with respect to both colour parameters (a and b) were 10% CO2 + 3% O2 and 20% CO2 + 3% O2 combinations (Fig. 1). 3.2. Physical, chemical and sensory changes determined in pickle samples Changes in the pickles samples of cucumber cv. ‘Octobus’ were determined in two separate groups, on treatment basis. In the first group, the performance of all treatments during processing to pickle after 10-day storage were given since the processing of cucumbers stored in NA conditions to pickle was not possible after 20 and 30 days of storage, as was explained in the ‘materials and methods’ section. In the second group, changes in the physical, chemical and sensory parameters were examined with the same time intervals as in the storage periods in the samples taken at different stages periods in the samples taken at different stages during 30-day storage (10, 20 and 30 days) from 4 different CA treatments other than those stored in NA, 6 months after processing to pickle. 3.2.1. Physical changes Result of the physical analyses determined in the samples taken from all treatments subjected to 10-day storage and from CA treatments (0% CO2 + 21% O2: 10 + 3; 20 + 3; 10 + 5; 5 + 10) subjected to 30-day storage are given in Tables 3 and 4. As can be seen in Table 3, no significant differences were determined in the vacuum values of pickles at the

beginning of storage and after 10-day storage under different conditions. Similar situation is also observed in the pickles made from the produce stored 30 days under CA conditions (Table 4). Differences observed in the vacuum values of treatments in Tables 3 and 4 are related to the empty volume left on the top during filling. It was determined that treatments with high empty volume on the top had low vacuum values. Gross, net and strained weight values of all samples were approximate to each other and changes determined when the ratios of strained weight net weight 1 were compared were not at significant levels. It was also noteworthy that 10% CO2 + 3% O2 treatment which gave the lowest strained weight net weight 1 ratio in the pickles made from the samples stored for 30 days also gave the lowest weight loss ratio at the end of storage (Table 2), and the highest FFF ratios either after storage or after processing to pickle (Tables 2 and 4). The pickles made from the cucumbers cv. Octobus stored under different conditions exhibited reductions in FFF values (Tables 3 and 4). This situation which has developed as expected indicated that the pickles made from the cucumbers stored under CA conditions maintained the FFF values at much higher levels compared with those made from NA-stored ones. Among the CA conditions consisting of storage up to 30 days, 5% CO2 + 10% O2 combination was deficient compared with the others, this situation became more pronounced with 10% CO2 + 5% O2 treatment on the 30th day. CA combinations of 10% CO2 + 3% O2 and 20% CO2 + 3% O2 gave more positive results at statistically significant level with respect to FFF values (Table 4). 3.2.2. Chemical changes Results of the chemical analyses carried out in pickles manufactured from the cucumbers taken from all CA

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Table 7 Results of the sensory evaluation related to the pickles manufactured from cucumbers cv. ‘Octobus’ stored in CA conditions for 30 days Storage period (days)

Treatment (CO2%:O2%)

Appearance (0–10)a b

Colour (0–10)

Odour (0–10)

Flavour (0–10)

Firmness (0–10)

7.33 a

6.83 a

6.67 a

8.50 a

0

0:21

5.67 d

10

0:21 10:3 20:3 10:5 5:10

6.33 7.33 7.50 7.67 7.50

d bc b ab b

5.33 7.00 7.00 6.83 6.33

c a a ab abc

5.17 6.17 5.83 6.50 5.67

c abc abc ab abc

5.83 5.50 6.00 6.17 5.83

abc bc ab ab abc

6.83 8.17 8.67 8.33 7.67

e abc a ab bcd

20

0:21 10:3 20:3 10:5 5:10

0.00 8.50 7.33 6.50 4.67

g a bc cd e

0.00 6.33 7.17 6.33 5.83

e abc a abc bc

0.00 5.67 5.83 5.80 4.00

g abc bc abc d

0.00 5.83 5.50 4.80 2.17

f abc bc c d

0.00 7.50 7.17 6.00 2.17

i cde de f g

30

0:21 10:3 20:3 10:5 5:10

0.00 1.83 2.00 1.50 1.50

g f f f f

0.00 1.00 1.83 1.17 1.00

e d d d d

0.00 3.00 3.00 2.33 1.33

g de de ef f

0.00 1.33 1.83 1.33 0.67

f de d de ef

0.00 2.17 2.17 0.83 0.67

i g g h hi

LSD

0.89

0.92

1.03

0.98

0.71

a

10: Extra ordinary, 9: excellent, 8: very good, 7: good, 6: above average, 5: average, 4: below average, 3: limit, 2: bad-defected, 1: very bad, 0: inconsumable. b Different letters in the same column indicate significant differences P < 0.05. LSD, least significant difference.

treatments with 10-day storage and 30-day storage are given in Tables 5 and 6. As can be seen in the mentioned tables, total dry matter contents of treatments declined with the prolonging storage period of the cucumbers to be processed to pickle. Differences determined between the total dry matter values of pickles manufactured from the cucumbers stored under different conditions for 10 days, at the time and treatment level were found not significant (Table 5). This situation continued in the samples produced from the cucumbers stored under CA conditions for 20 days. Nevertheless, significant differences were determined at the time and treatments level by prolonging the storage period to 30 days. In this respect, 5% CO2 + 10% O2 treatment in which the lowest dry matter was obtained has drawn attention with the differences between the treatments and beginning of storage (Table 6). When the TA values of treatments are considered, significant reductions were determined in the treatments processed to pickle on the 10th day of storage (Table 5). This significance which was determined at the time level was not reflected to the difference between the treatments. The TA values in the pickles obtained from CA treatments in the later stages of storage were determined to remain more stable and the differences at the time and treatments level were found insignificant (Table 6). It was observed that there were increases in the pH values of treatments and contrarily to the increases in TA values and these increases were parallel to the reductions in acidity values (Tables 5 and 6). When Table 6 is examined, it can be clearly seen that the changes in TA and pH values are contradictory to each other. According to this, the treatment which gave the highest TA values (5% CO2 + 10% O2) gave the lowest

pH value, whereas the treatment which gave the highest pH value (10% CO2 + 5% O2) gave the lowest TA value in the pickles produced from the cucumbers stored in CA treatments for 30 days. Another noteworthy point here is that these two treatments had contradictory atmosphere combinations with respect to O2 and CO2 values. When the salt values if treatments were examined from Tables 5 and 6, reductions were determined especially by the 20th day of storage. Nevertheless, the differences between the salt values of treatments were observed to be non significant in the pickles produced from the samples taken after 30-day CA storage (Table 6). The reduction in the total chlorophyll contents of cucumbers was reflected to the pickle samples with the prolonging storage period (Tables 5 and 6). Significant reductions were observed in the total chlorophyll values of pickles obtained from the samples at the end of the first 10 days of storage in all treatments (Table 5). This situation persisted after the processing of samples on the 30th day of storage, although there were differences at the treatments level. At the end of the storage, the differences between the treatments were determined to be non significant (Table 6). 3.2.3. Sensory changes As can be seen in Table 7, the results of the sensory evaluations related to the pickles manufactured from cucumbers cv. ‘Octobus’ appears as a complete reflection of the performance (Table 2) exhibited by these cucumbers during storage with different treatments. Reductions were determined in the sensory evaluation values of pickles obtained from the samples with the prolonging storage period. After the 10th day of storage, sensory evaluation changes in NA

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cucumbers which exhibit the worst performance with respect to the quality criteria examined during this analytical period (e.g. weight loss, FFF, total chlorophyll and overall appearance-Table 1), were not taken under observation since these cucumbers could not be used in pickle production. The highest scores were obtained from 10% CO2 + 3% O2 and 20% CO2 + 3% O2, and the lowest from 10% CO2 + 5% O2 and 5% CO2 + 10% O2 CA treatments, due to the examination of the pickles obtained from the samples stored for 30 days (Table 7). This situation supports the changes determined along the storage period. 4. Discussion It was observed in the studies on the CA storage of pickling cucumbers with the aim of prolonging their storage retaining their quality that the spoilage could be inhibited for 1 week in NA, and for 2–3 weeks under CA conditions in which CO2 rates ranged from 3% to 20% and O2 rates from 3% to 5% (Buescher, 1987; Saltveit, 2001; Salunkhe & Desai, 1984). In our study which was carried out under similar conditions with cv. ‘Octobus’ at the storage temperatures and atmosphere combinations given in the above studies the highest weight loss ratio at the end of storage was determined in NA conditions, and the lowest in 10 + 3 and 20 + 3 (CO2% + O2%) CA combinations. Wang (1999), attributed the minimization of chilling injury in cucumbers via modified atmosphere packaging (MAP) to the reduction in water loss under high relative humidity conditions, since the reduction of water loss in the chilling sensitive tissues of cucumbers under high relative humidity inhibits the occurrence of chilling-dependent destruction of the cells on and below epiderm, and this situation prevents the development of spotting and other similar symptoms. However, in addition to this direct effect of cover material towards the maintenance of high relative humidity in the environment, the water loss, hence the weight loss can be kept at lower levels owing to the lower metabolical activity resulting from the suppression of respiration rate by low O2 and high CO2 conditions in the package. The relation between respiration rate and weight loss was also determined by Hakim et al. (2000). These results, supportingly explain the findings of Wang (1999) and Hakim et al. (2000) related to lower weight loss ratios determined in CA treatments consisting of high CO2 and low O2 conditions compared with NA conditions, as was observed in our study. The maintenance of respiration rate at lower levels in CA-stored fruits compared with NA-stored ones at the end 30-day storage of fresh pickling cucumbers is similar to the results about the suppression of respiration rate by CA in the related studies (Nakano, Zhong, Yasunaga, & Akimoto, 1998; Wang, 1999). Moreover, the situation similar to the relation between the respiration rates and weight loss rates determined in our study is also noteworthy, as reported by Hakim et al. (2000) (Table 2). The results obtained from our study are in accordance with the results

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reported by Kubo, Inaba, Kıyasu, and Nakamura (1989) towards the inhibition of respiration in cucumbers via high CO2 conditions. In addition, it was reported in a study made on this subject that the respiration rates of cucumber fruits were basically affected by O2 ratios, yet the direct effect was temperature-dependent (Yasunaga, Uchino, Zhong, & Hamanaka, 2002). Srilaong and Tatsumi (2003) reported that storage in 100% O2 at 5 C was the most effective combination for the suppression of respiration rate in cucumber fruits, compared with the ratios of 5% and 21%. Lower levels of weight loss ratios in CA treatments in our study compared with NA conditions is important with respect to retardation of tissue softening in these treatments (Table 2). As usually known, the power of intercellular connections is maintained by pectins. Enzymatical destruction of polysaccharides in cell wall such as pectin and cellulose, and separation of water-insoluble protopectins from the middle lamella after changing into a water soluble form weaken the cellular connections and reduce the resistance by separating the cells from each other. This undesirable change in the structure can be prevented or minimized by the inactivation of cellulose, pectinesterase and polygalacturonase enzymes. Kim and Hall (1976) reported that 3% O2 level retarded this structural disorder in tomatoes. Also, in our study in which the combination of 3% O2 with high CO2 rates are experimental, FFF values were maintained at much higher levels compared with NA conditions (Table 2). Insignificant differences determined in the TSS ratios of treatments at the end of 30-day storage may be explained as the reflection of the differences in the weight loss ratios of treatments. The highest weight loss and respiration rate values as well as the lowest FFF, TSS and TA values in our study at the end of storage were obtained from NA and 5% CO2 + 10% O2 treatments (Table 2). This situation may originate from the fast metabolical activity dependent on high respiration rate. The highest pH values were determined in these two treatments in which the lowest TA values were obtained, as expected. Increases determined in pH values contrarily to the decline in TA values along the storage period are similar to the results of Naruke et al. (2003) and Srilaong and Tatsumi (2003). Srilaong and Tatsumi (2003) stored the cucumber fruits at 5 C and 5%, 21% and 100% O2. Storage at 100% O2 was determined as the most effective and treatment for the suppression of respiration rate. Succinate dehydrogenase (SDH) activity in the study was lower in cucumber fruits stored at 100% O2. The pH increased under the three atmosphere conditions during storage, however, it was found lower in the fruits kept at 100% O2. These results were explained as that the suppression of SDH activity in the medium rich in O2could lead to a reduction in pH change. As usually known, cucumbers are susceptible to chilling injury at the temperatures lower than the optimum storage temperature with the prolonging storage period and to yellowing at high temperatures (Ryall & Lipton, 1979;

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Salunkhe & Desai, 1984). The risk of chilling injury is also brought up by chlorophyll loss ratio (De Ell et al., 2000; Hakim et al., 2000). Metabolism as well as respiration rate was slowed down in the CA medium created by reducing the O2concentration and the other disintegration processes were also retarded accordingly, as in the chlorophyll loss (Karacalı, 1993). Studies on this subject show that the chlorophyll content of vegetables such as broccoli, cucumber, fresh beans and spinach are preserved most effectively under the storage conditions established by raising CO2 level and lowering O2 level (Do & Salunkhe, 1975). As a matter of fact, the lowest value in the total chlorophyll values decreasing with the prolonging storage period was determined in NA treatment also in our study (Table 2). This situation is supported by the results of fruit skin colour and fruit flesh colour with the lowest green colour (a) and the highest yellow colour (b), respectively, belonging to NA treatment at the end of storage (Fig. 1). However, chilling temperatures should be avoided in CA storage due to the probability of increased chilling injury caused by high CO2, low temperature and low O2 values (Ryall & Lipton, 1979; Salunkhe & Desai, 1984). Ion leakage values which increased at insignificant levels at the end of storage were coincided in the fresh pickling cucumbers cv. ‘Octobus’ stored at 7 C for 30 days (Table 2). This situation was accepted as a natural result depending on the metabolical activity and permeabilities in cellular membranes continuing in the cucumbers in which no chilling injury was coincided. Nevertheless, especially the increase in the ion leakage is known as a result induced by chilling injury (Maezawa & Akimoto, 1998; Rab & Ishtiaq, 1997). At the end of the storage, NA fruits gave the lowest overall appearance valve among the treatments in our study (Table 2). This situation apparently supports the result in which the most adverse reflections were observed with respect to the postharvest quality criteria (weight loss, respiration rate, FFF, total chlorophyll and colour of fruit skin and fruit flesh) examined in the NA treatment in our study. Differences in the vacuum quantities of treatments is related to the top space volume remained during filling as well as to the brine temperature, and the sample with larger top space had a low vacuum level in the samples with the same filling temperature, as can be seen in Tables 3 and 4. In this situation, there is a negative correlation between top space and vacuum (Cemeroglu, 1992; Kramer & Twigg, 1983; Luh & Woodroof, 1982). The results obtained from our study confirm the negative correlation between top space and vacuum, in accordance with the references above. The top space quantities and vacuum, gross, net and strained weights of treatments are in approximate values, and the difference observed in some samples is thought to be originating from the slight differences in the weights of cucumbers in the jar due to the volume differences originating from the sizes of raw material, although the initial filling quantity was decided on weight basis. When the ratios

of filtration weight net weight 1 are considered, 10% CO2 + 3% O2 treatment preserved this ratio at close values even during different periods. The lowest ratio among the treatments processed to pickle from the samples stored for 30 days. This situation may result from the failure in penetration of the brine into the structure of cucumbers due to the fact that the same treatment gave the lowest weight loss at the end of storage and the highest FFF value after processing to pickle. However, the reduction in firmness values of pickle samples proportionally to their storage period is in accordance with the changes in the same treatments which from the raw material, along the storage period (Table 2). The lowest FFF values determined in NA up to the 10th day and in 5% CO2 + 10% O2 treatment on the 30th day may be explained with high O2 values and hence rapid metabolical activities of these treatments. The high respiration rates determined during the same period also support this situation (Table 2). The gradual decline determined in the FFF values affected by the softening resulting from the losses in physical tissue and dry matter depending on the storage conditions and period is similar to the results of Ic, Ozcelik, and Denli (1999). The addition of compounds containing CaCl2 and Ca++ at suitable concentrations to the brine, pasteurization and use of preservatives are of the methods recommended for avoiding this negativity which appears as an important quality loss especially in the final product. Less firmness losses were coincided in the cucumbers which were subjected to thermal treatment after canning, due to the inhibitory effect of temperature on the activity of pectolytical enzymes (Buescher & Hudson, 1984; Guillou, Floros, & Cousin, 1992). Total dry matter contents of treatments which were determined between 6.47 and 8.54% (Tables 5 and 6), are in accordance with the values reported by Dogan and Sahin (2000) and Sahin and Akbas (2001). Differences between the treatments may originate from the textural changes and matter exchange in cucumbers due to the storage period and conditions. Researchers also stated that the dry matter content of pickle is related to the fruit size as well as to the treatments, and that the dry matter content decreased as the fruit size increased (Lu, Fleming, & McFeeters, 2002; Sahin & Akbas, 2001). Moreover, the declines in firmness values occurred with the prolonging storage period may have leaded to decreases in dry matter, as well. The acidity ratio in the pickles obtained from the cucumbers cv. ‘Octobus’ after the establishment of mass equilibrium was determined to change between 0.79% and 1.23% and the pH values between 4.20 and 4.61. pH value of the sample with the highest total acid quantity was naturally found the lowest (Table 6). Flemıng, Daeschel, McFeeters, and Pierson (1989) determined the acidity value of fermented pickles on the 30th day as 1.09%, while Guillou et al. (1992) determined this value as 0.2–1% in the 2nd week of fermentation. The results obtained show similarities despite the differences in application. The pH values were found between values (3.1–4.9) given by Guillou et al. (1992). The salt contents

B. Akbudak et al. / Journal of Food Engineering 78 (2007) 1034–1046

of samples ranged from 1.03% to 1.44%. The fact that the salt content was found lower than the values determined by Ic et al. (1999) (3.07–5.35%) is due to the processing of cucumbers for sweet pickle production. Chlorophyll contents of cucumbers decreased with the prolonging storage period and this situation reflected to pickles, as well. At the end of the storage, CA treatment with 5% CO2 + 10% O2 combination which gave the lowest total chlorophyll value expect NA treatment (Table 2) also gave the lowest value in pickles, similarly (Table 6). The inhibition in total chlorophyll losses under suitable CA conditions (10–20% CO2 + 3–5% O2) are similar to the results of Do and Salunkhe (1975) which indicate that the storage conditions obtained by raising the CO2 level and lowering the O2 level effectively maintain the chlorophyll content. According to the result of the sensory evaluation, the lowest scores related to 10-day storage period were taken by NA treatment with respect to the criteria of appearance, colour, flavour, taste and firmness. The lowest scores among CA treatments on the 20th and 30th days were obtained from 10% CO2 + 5% O2 and 5% CO2 + 10% O2 treatments, expect NA treatment which was not processed to pickle beyond the 10th day. 20% CO2 + 3% O2 and 10% CO2 + 3% O2 treatments got the highest scores in all analytical periods, with regard to the criteria examined. These results which were obtained in the quality criteria after processing to pickle, are completely in accordance with the results obtained regarding the postharvest quality criteria in the same treatments in which the stored fruits constitute the raw material. The results obtained from 20% CO2 + 3% O2 and 10% CO2 + 3% O2 treatments which were also used in our study are in accordance with the findings of Buescher (1987). 5. Conclusion Fresh pickling cucumbers cv. ‘Octobus’ could be stored less than 10 days under NA conditions consisting of 7 C temperature and 90–95% relative humidity. However, the storage periods could be prolonged up to 30 days with acceptable quality losses under the same storage conditions, provided that the suitable atmosphere combinations are used (especially 10% CO2 + 3% O2 or 20% CO2 + 3% O2). Nevertheless, restricting the pre-processing storage of cucumbers to 20 days even under suitable CA conditions may give more convenient results that will satisfy the consumer in physical, chemical and sensory aspects, if the effect of raw material on the quality of the final product is considered. Acknowledgement We wish to thank agricultural engineer M. Gunduz and Penguen Food Industry and Trade Co. for their help in providing the fruit material.

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