Chapter 19
Off-Flavor Development of Apples, Pears, Berries, and Plums Under Anaerobiosis and Partial Reversal in Air 1
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Daryl G. Richardson and Manit Kosittrakun Downloaded by MONASH UNIV on November 27, 2015 | http://pubs.acs.org Publication Date: May 5, 1995 | doi: 10.1021/bk-1995-0596.ch019
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Department of Horticulture, Oregon State University, Corvallis, OR 97331-7304 Department of Horticulture, Kasetsart University, Bangkok, Thailand
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Responses of several fruit types to static N or flowing streams (10 mL/ min) of low O concentrations at 0°C or 20°C were investigated. Large differences in anaerobic responses were observed between varieties of the same fruit type. A t 0°C 'Granny Smith' apple and 'd'Anjou' pear did not synthesize detectable off-flavors for at least 20 days in N , whereas 'Golden Delicious' apple and 'Bartlett' pears developed off-flavors after only 5-8 days. A t 20°C, both varieties of apples and pears synthesized off flavors in N , but 'Anjou' pear and 'Granny Smith' apple produced much less. Although off-flavor, ethanol and acetaldehyde increased under anaerobic conditions, the reversibility of off-flavor without much change in tissue ethanol or acetaldehyde, casts doubt on any direct connection between these compounds and off-flavor. 'Blue Jay' blueberries, 'Amity' red raspberries, 'Marion' blackberries, and 'Italian' plums were placed in static N or continuous flow (10 ml/min) low O (0.3 to 4.3%) at 0°C. For all fruits treated, accumulated CO and headspace ethanol increased with time in static N . Blueberries, red raspberries, blackberries and plums could be kept in anaerobic conditions at 0°C for up to 9, 7,4, and 5 days, respectively without developing off-flavors. Storage beyond these periods for a few days resulted in slight off-flavors which dissipated after transferring fruits to air cold storage for 3 days. Longer anaerobic storage resulted in off-flavors which did not completely dissipate. In low-O storage conditions, headspace ethanol increased with time in storage and with decreasing O concentration. Small fruits held in 1.3% O and plum kept in 0.5% O for 10 days developed slight off-flavors, but recovered within 3 days upon transfer to air. While off-flavors could be at least partially reversed in air, changes in acetaldehyde or ethanol were very slight and these two compounds could not account for the changes in off-flavor. 2
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0097-6156/95/0596-0211$12.00/0 © 1995 American Chemical Society In Fruit Flavors; Rouseff, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1995.
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FRUIT FLAVORS
Controlled atmosphere (CA) storage has long been used successfully to extend postharvest life, and maintain quality of certain horticultural commodities, especially apples and pears. However, its potential application as an alternative to chemical fumigation to control insects of quarantine importance has not been thoroughly investigated. Storage in l o w - 0 (1.0 to 1.5%) atmospheres with and without C 0 (0 to 2.0%) resulted in better retention of flesh firmness and titratable acidity in apples (1,2,3,4,5,6) and better dessert quality and suppression of superficial scald and stem-end decay in pears (7,8,9). Use of C A as a quarantine treatment against insects in grains and stored products has been also well documented (10,11,12). Low oxygen concentration was more important in reducing the time to kill insects than C 0 concentration (13). L o w - 0 (
