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The Influence of Controlled Atmosphere Storage on Browning of d'Anjou Pear Juice and Concentrate
Can. lnsf. Food Sci. Technol. J. Vol. 23, No. 4/5, pp. 233-235, 1990
RESEARCH NOTE
The Influence of Controlled Atmosphere Storage on Browning of d'Anjou Pear Juice and Concentrate 1 T. Beveridge, M. Meheriuk and J.E. Harrison Agriculture Canada Research Station Summerland, British Columbia YOH IZO
Abstract Nonenzymatic browning rates were followed in juice and concentrate of d' Anjou pears stored for 90, 150 and 210 days in an atmosphere of 2070 O2 and 1070 CO 2 at O°C. Concentrate from pears stored for 210 days browned significantly faster at 80°C than concentrate produced from pears stored for 90 or 150 days. Storage time did not affect the browning rates of the juices.
Resume Les taux de brunissement non enzymatique furent determines dans des jus et des concentre de poires d'Anjou stockes pendant 90, 150 et 210 dans une atmosphere de 2070° 2 et 1070 CO 2 a O°C. Les concentres de poire stockes pendant 210 jours brunirent significativement plus vite a 80°C que ceux obtenus de poires stockes pendant 90 ou 150 jours. La duree d'entreposage n'a pas affecte les taux de brunissement des jus.
Introduction Nonenzymatic browning of pear juice and especially of concentrate during production and storage jeopardizes the value of these products (Beveridge and Harrison, 1984; 1987). Pear juice is commonly produced from cull fruit and pear peel and core material (Beveridge et al., 1988) which have been stored for variable periods of time prior to processing. However, the possible effects of fruit storage on browning have not been considered. Maillard browning proceeds through condensation of amino nitrogen with the carbonyl groups of reducing sugars (Tressler and Joslyn, 1954) or through sugar fragmentation and free radical formation (Namiki and Hayashi, 1983). Hydrolysis of proteinaceous material during pear storage could result in elevated non-protein amino nitrogen levels and enhanced browning of juice products from such pears. The preliminary study reported here was intended to examine the possible effects of pear storage on pear juice and pear concentrate stability. 'Contribution No. 749, Research Station, Summlerland, British Columbia YOH IZO
Materials and Methods 0'Anjou pears from Summerland Research Station plots were stored in an atmosphere of 2.0010 O2 and 1.0% CO2 at O°C. After 90, 150 and 210 d, pears were removed from storage and juice was produced by hammermilling and pressing. Four replicates of 5 to 10 L were prepared on each removal date. Pressed juice was clarified by adding 2 mL of bentonite suspension (5% bentonite in press juice, hydrated 4 h at room temperature) to 1 L of pressed juice. Treated juice was held at 5°C for 24 h and the clarified portion was carefully decanted from the lees. The clarified juice was filtered through diatomaceous earth (previously washed with 1% malic acid (w/v), water, and then dried) to brilliance. Dark brown pigment in the juice, produced by polyphenol oxidase activity prior to and during pressing operations was removed with activated charcoal (7-10 giL; Darco 0-60). The stirred charcoal-juice mixture was held for 15 min then vacuum filtered through a thin pad of diatomaceous earth. All decolorized juices were pasteurized by rapid heating to 80°C in a microwave oven followed by rapid cooling in an ice bath. Final filtration was done through a 2 Jl millipore filter. Juice concentrate was prepared by rotatory evaporation of pear juice at 40°C in a rotary evaporator (Brinkman rotovaporEL) to 60 °Brix. Sugar content was measured as °Brix using an Abbe Mark II refractometer (AO Scientific Instruments, Buffalo, NY.). Water activity was measured at 25°C with a Rotronic Hydroskop DT (Rotronic Instrument Corp., Huntington, NY.) water activity meter equipped with OMS 100 cells and operated according to the manufacturers instructions. Amino nitrogen was determined by the TNBS method outlined by Beveridge and Harrison 1985), with the exception that a Varian OMS 100 UV-visible pectrophotometer equipped with a routine sampler
Copyright © 1990 Canadian InSlilute of Food Science and Technology
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Fig. I. Browning of d' Anjou pear juice at 80°C. Each point represents the average of four replicates. Error bars represent the standard error of the mean.
Fig. 2. Browning of d'Anjou pear juice concentrate at 80°C. Each point represents the average of four replicates. Error bars represent the standard error of the mean.
and a DS-15 data station was used to read absorbance values.
extensive period at 80°C to achieve significant brown color development (Figure 1). This is reasonable since amino acid levels in juice are low and therefore restrict browning reactions. Pear storage had no effect (P $ 0.05) on the extent of browning of thermally stressed pear juice. The concentrate browned much more rapidly than the juice (Figure 2), a reflection of the exponential increase in browning rates which occurs with reduced water activity (Table 1) and the increase in reactant concentration with water removal (Eichner and Karel, 1972). Duration of CA-storage prior to processing affected subsequent browning of pear juice concentrate. Concentrate from pears stored 210 d browned significantly faster (p $0.001) than concentrate from pears stored 90 or 150 d. These latter two preparations were not significantly different (P ~0.05) from each other. Since a correlation has been shown to exist between browning rates at 80°C and browning rates at lower non-frozen storage temperatures (Beveridge and Harrison, 1987), pear juice concentrate production from pears stored for 210 d should be avoided as color instability problems during production and
Accelerated Storage of Juice and Concentrate Ten millilter samples of juice or 60 °Brix concentrate, respectively, were placed in 15 mL-screw cap test tubes. Samples were tightly sealed and immersed in an 85°C water bath. Juice and concentrate temperatures were monitored by thermocouples centrally immersed in several tubes. Water bath temperature was adjusted to maintain sample temperatures at 80 ± 2°C. After approximately 10 min the sample centre temperature had reached 80°C, this was designated as time zero. Tubes were removed from the water bath at various intervals over a period of 250 min for concentrate and 7 d for juice and then cooled in an ice bath. Samples were analyzed for color change at 420 nm with a Varian DMS 100 UV-Visible Spectrophotometer equipped with 1 cm cells and a DS-15 data station.
Statistical Analyses Analyses of Variance were conducted utilizing SAS (SAS Institute Inc., Cary, NC., version 5.18) to determine the effect of pear storage time on Maillard browning of the juice and concentrate.
Table I. Soluble Solids and Water Activity in Pear Juice and Concentrate' .
Results and Discussion Pear storage .time had no significant effect (p ~ 0.05) on the amino nitrogen content of the initial juices. Average amino acid content of the juices was 4.00 ± 0.48 mM glycine, which is in good agreement with previously reported values for d'Anjou pears and pear juice (Chen et al., 1982; Beveridge et al., 1986). All juices required an 234 I Beveridge et al.
Sample Juice
Parameter Soluble Solids (OBrix) Water Activity (25°C)
Pear Storage Time (Days) 90 150 210 9.5 0.95
8.2 0.95
9.0 0.94
Concentrate Soluble Solids (OBrix) 60.2 60.1 60.2 Water Activity (25°C) 0.81 0.81 0.82 I Values shown are averages of four replicate preparations. J. lnst. Can. Sci. Technol. Aliment. Vol. 23. No. 4/5. 1990
storage may result. However, juice produced from long-stored pears showed no color instability problems and would be acceptable for applications requiring juice alone.
References Beveridge, T., and Harrison, J.E. 1984. Nonenzymatic browning in pear juice concentrate at elevated temperatures. J. Food. Sci. 49: 1335. Beveridge, T., and Harrison, J .E. 1985. Amino nitrogen in fruit juice, juice concentrates and fruit drinks determined with 2,4,6-trinitrobenzene-sulfonic acid. Can. Inst. Food Sci. Techno!' J. 18:259. Beveridge, T., Harrison, LE., Bains, D. 1986. Pilot scale production and composition of juice from heated pear mashes. Lebensm. Wiss. Techno!. 19:432. Beveridge, T., and Harrison, J .E. 1987. Storage br?wning of pear juice concentrate. Can. Inst. Food SCI. Techno!. J. 20:170.
Can. lnsi. Food Sci. Technol. J. Vol. 23, No. 4/5, 1990
Beveridge, T., Harrison, J .E., and Kitson, J .A. 1988. Pear juice from Bartlett pear peels and cores. 1. Food Sci. 53:1195. Chen, P.M., Richardson, D.G.: and Mell~~thin, W.M; 1982. Differences in biochemical composItIOn between Beurre d' Anjou' and 'Bosc' pears durin~ fruit development and storage. J. Amer. Soc. Hort: SCI. 101 :807. Eichner, K., and Karel, M. 1972. The mfluence of w~ter cont~nt and water activity on the sugar-amino b~~wnmg reactl?n in model systems under various conditions. J. Agnc. Food Chern. 20:218. Namiki, M., and Hayashi, T. 1983. A new mechanism of the Maillard reaction involving sugar fragmentation and free radical formation. In: The Maillard Reaction in Foods and Nutrition. G.R. Walker and M.S. Feather (Eds.). p. 21. American Chemical Society, Washington, DC. Tressler, D.K., and Joslyn, M.A. 1954. Fruit and Vegetable Juice Production. p. 232. AVI Publishing Co., New York. Submitted April 1, 1990 Revised June 15, 1990 Accepted June 18, 1990
Beveridge et al. / 235
RESEARCH NOTE
The Influence of Controlled Atmosphere Storage on Browning of d'Anjou Pear Juice and Concentrate 1 T. Beveridge, M. Meheriuk and J.E. Harrison Agriculture Canada Research Station Summerland, British Columbia YOH IZO
Abstract Nonenzymatic browning rates were followed in juice and concentrate of d' Anjou pears stored for 90, 150 and 210 days in an atmosphere of 2070 O2 and 1070 CO 2 at O°C. Concentrate from pears stored for 210 days browned significantly faster at 80°C than concentrate produced from pears stored for 90 or 150 days. Storage time did not affect the browning rates of the juices.
Resume Les taux de brunissement non enzymatique furent determines dans des jus et des concentre de poires d'Anjou stockes pendant 90, 150 et 210 dans une atmosphere de 2070° 2 et 1070 CO 2 a O°C. Les concentres de poire stockes pendant 210 jours brunirent significativement plus vite a 80°C que ceux obtenus de poires stockes pendant 90 ou 150 jours. La duree d'entreposage n'a pas affecte les taux de brunissement des jus.
Introduction Nonenzymatic browning of pear juice and especially of concentrate during production and storage jeopardizes the value of these products (Beveridge and Harrison, 1984; 1987). Pear juice is commonly produced from cull fruit and pear peel and core material (Beveridge et al., 1988) which have been stored for variable periods of time prior to processing. However, the possible effects of fruit storage on browning have not been considered. Maillard browning proceeds through condensation of amino nitrogen with the carbonyl groups of reducing sugars (Tressler and Joslyn, 1954) or through sugar fragmentation and free radical formation (Namiki and Hayashi, 1983). Hydrolysis of proteinaceous material during pear storage could result in elevated non-protein amino nitrogen levels and enhanced browning of juice products from such pears. The preliminary study reported here was intended to examine the possible effects of pear storage on pear juice and pear concentrate stability. 'Contribution No. 749, Research Station, Summlerland, British Columbia YOH IZO
Materials and Methods 0'Anjou pears from Summerland Research Station plots were stored in an atmosphere of 2.0010 O2 and 1.0% CO2 at O°C. After 90, 150 and 210 d, pears were removed from storage and juice was produced by hammermilling and pressing. Four replicates of 5 to 10 L were prepared on each removal date. Pressed juice was clarified by adding 2 mL of bentonite suspension (5% bentonite in press juice, hydrated 4 h at room temperature) to 1 L of pressed juice. Treated juice was held at 5°C for 24 h and the clarified portion was carefully decanted from the lees. The clarified juice was filtered through diatomaceous earth (previously washed with 1% malic acid (w/v), water, and then dried) to brilliance. Dark brown pigment in the juice, produced by polyphenol oxidase activity prior to and during pressing operations was removed with activated charcoal (7-10 giL; Darco 0-60). The stirred charcoal-juice mixture was held for 15 min then vacuum filtered through a thin pad of diatomaceous earth. All decolorized juices were pasteurized by rapid heating to 80°C in a microwave oven followed by rapid cooling in an ice bath. Final filtration was done through a 2 Jl millipore filter. Juice concentrate was prepared by rotatory evaporation of pear juice at 40°C in a rotary evaporator (Brinkman rotovaporEL) to 60 °Brix. Sugar content was measured as °Brix using an Abbe Mark II refractometer (AO Scientific Instruments, Buffalo, NY.). Water activity was measured at 25°C with a Rotronic Hydroskop DT (Rotronic Instrument Corp., Huntington, NY.) water activity meter equipped with OMS 100 cells and operated according to the manufacturers instructions. Amino nitrogen was determined by the TNBS method outlined by Beveridge and Harrison 1985), with the exception that a Varian OMS 100 UV-visible pectrophotometer equipped with a routine sampler
Copyright © 1990 Canadian InSlilute of Food Science and Technology
233
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90 Days 150 Days 210 Days
0.0 "-_-'-_--'-_ _'--_...L..-_-'-_--"-_ _'--_..J.. 90 120 150 180 210 240 60 30
o
TIME (h)
TIME (min)
Fig. I. Browning of d' Anjou pear juice at 80°C. Each point represents the average of four replicates. Error bars represent the standard error of the mean.
Fig. 2. Browning of d'Anjou pear juice concentrate at 80°C. Each point represents the average of four replicates. Error bars represent the standard error of the mean.
and a DS-15 data station was used to read absorbance values.
extensive period at 80°C to achieve significant brown color development (Figure 1). This is reasonable since amino acid levels in juice are low and therefore restrict browning reactions. Pear storage had no effect (P $ 0.05) on the extent of browning of thermally stressed pear juice. The concentrate browned much more rapidly than the juice (Figure 2), a reflection of the exponential increase in browning rates which occurs with reduced water activity (Table 1) and the increase in reactant concentration with water removal (Eichner and Karel, 1972). Duration of CA-storage prior to processing affected subsequent browning of pear juice concentrate. Concentrate from pears stored 210 d browned significantly faster (p $0.001) than concentrate from pears stored 90 or 150 d. These latter two preparations were not significantly different (P ~0.05) from each other. Since a correlation has been shown to exist between browning rates at 80°C and browning rates at lower non-frozen storage temperatures (Beveridge and Harrison, 1987), pear juice concentrate production from pears stored for 210 d should be avoided as color instability problems during production and
Accelerated Storage of Juice and Concentrate Ten millilter samples of juice or 60 °Brix concentrate, respectively, were placed in 15 mL-screw cap test tubes. Samples were tightly sealed and immersed in an 85°C water bath. Juice and concentrate temperatures were monitored by thermocouples centrally immersed in several tubes. Water bath temperature was adjusted to maintain sample temperatures at 80 ± 2°C. After approximately 10 min the sample centre temperature had reached 80°C, this was designated as time zero. Tubes were removed from the water bath at various intervals over a period of 250 min for concentrate and 7 d for juice and then cooled in an ice bath. Samples were analyzed for color change at 420 nm with a Varian DMS 100 UV-Visible Spectrophotometer equipped with 1 cm cells and a DS-15 data station.
Statistical Analyses Analyses of Variance were conducted utilizing SAS (SAS Institute Inc., Cary, NC., version 5.18) to determine the effect of pear storage time on Maillard browning of the juice and concentrate.
Table I. Soluble Solids and Water Activity in Pear Juice and Concentrate' .
Results and Discussion Pear storage .time had no significant effect (p ~ 0.05) on the amino nitrogen content of the initial juices. Average amino acid content of the juices was 4.00 ± 0.48 mM glycine, which is in good agreement with previously reported values for d'Anjou pears and pear juice (Chen et al., 1982; Beveridge et al., 1986). All juices required an 234 I Beveridge et al.
Sample Juice
Parameter Soluble Solids (OBrix) Water Activity (25°C)
Pear Storage Time (Days) 90 150 210 9.5 0.95
8.2 0.95
9.0 0.94
Concentrate Soluble Solids (OBrix) 60.2 60.1 60.2 Water Activity (25°C) 0.81 0.81 0.82 I Values shown are averages of four replicate preparations. J. lnst. Can. Sci. Technol. Aliment. Vol. 23. No. 4/5. 1990
storage may result. However, juice produced from long-stored pears showed no color instability problems and would be acceptable for applications requiring juice alone.
References Beveridge, T., and Harrison, J.E. 1984. Nonenzymatic browning in pear juice concentrate at elevated temperatures. J. Food. Sci. 49: 1335. Beveridge, T., and Harrison, J .E. 1985. Amino nitrogen in fruit juice, juice concentrates and fruit drinks determined with 2,4,6-trinitrobenzene-sulfonic acid. Can. Inst. Food Sci. Techno!' J. 18:259. Beveridge, T., Harrison, LE., Bains, D. 1986. Pilot scale production and composition of juice from heated pear mashes. Lebensm. Wiss. Techno!. 19:432. Beveridge, T., and Harrison, J .E. 1987. Storage br?wning of pear juice concentrate. Can. Inst. Food SCI. Techno!. J. 20:170.
Can. lnsi. Food Sci. Technol. J. Vol. 23, No. 4/5, 1990
Beveridge, T., Harrison, J .E., and Kitson, J .A. 1988. Pear juice from Bartlett pear peels and cores. 1. Food Sci. 53:1195. Chen, P.M., Richardson, D.G.: and Mell~~thin, W.M; 1982. Differences in biochemical composItIOn between Beurre d' Anjou' and 'Bosc' pears durin~ fruit development and storage. J. Amer. Soc. Hort: SCI. 101 :807. Eichner, K., and Karel, M. 1972. The mfluence of w~ter cont~nt and water activity on the sugar-amino b~~wnmg reactl?n in model systems under various conditions. J. Agnc. Food Chern. 20:218. Namiki, M., and Hayashi, T. 1983. A new mechanism of the Maillard reaction involving sugar fragmentation and free radical formation. In: The Maillard Reaction in Foods and Nutrition. G.R. Walker and M.S. Feather (Eds.). p. 21. American Chemical Society, Washington, DC. Tressler, D.K., and Joslyn, M.A. 1954. Fruit and Vegetable Juice Production. p. 232. AVI Publishing Co., New York. Submitted April 1, 1990 Revised June 15, 1990 Accepted June 18, 1990
Beveridge et al. / 235