61B-30 |
Determination of changes in aroma active components in reconstituted orange juice during a time-temperature storage study using gas chromatography-olfactometry |
J. G. DREHER1, R. L. Rouseff1, and M. Naim2. (1) Food Science and Human Nutrition, University of Florida, 700 Experiment Station Rd., Lake Alfred, FL 33850-2299, (2) Institute of Biochemistry, Food Science and Nutrition, Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem Citrus juice is the dominant juice in the U.S market. Citrus juice is known to have a complex flavor that is highly unstable. Flavor stability and off-flavor development are the primary limitations of shelf life and consumer acceptance. The objective of this study was to identify the aroma active compounds found in reconstituted orange juice, their relative intensities, and how they change under various time-temperature conditions. Samples of commercially reconstituted orange juice were stored in glass at temperatures of 4, 25, and 35°C for up to 16 weeks. Juices were extracted with a 1:1 mixture of pentane: diethyl ether with an internal standard. Samples were analyzed, using gas chromatography-olfactometry with simultaneous flame ionization detection on DB-Wax and DB-5 columns. Time-intensity olfactometry was employed using two trained assessors in duplicate. At 35°C storage, the number of aroma active compounds decreased from 54 to 41 in 12 weeks. The most intense aroma active impact compounds at all temperatures include: methional, decanal, linalool, b-damascenone, b-ionone, 2,5-dimethyl-4-hydroxy-3(2H)-furanone, wine lactone, 4-vinyl guaiacol and vanillin. Of these compounds, methional, 2,5-dimethyl-4-hydroxy-3(2H)-furanone, and 4-vinyl guaiacol are known to be off-flavors in orange juice. Methional imparts a cooked potato note. It was found at all temperatures, but was especially intense at 25 and 35°C. 4-Vinly guaiacol, with a spicy aroma, increased in intensity with both time and temperature. Important aldehydes such as octanal, decanal, (Z)-3-hexenal, and (Z)-4-octenal were diminished or lost completely. Other less pleasant aldehydes such as (E,E)-2,4-nonadienal (fatty, green) and (E)-2-octenal (woody, musty) increased with increasing storage time and temperature. Results for this study, can be used for quality control purposes to identify specific off flavors. These off-flavor compounds can then be routinely monitored using instrumental analysis.
Session 61B, Food Chemistry: Flavor and aroma chemistry
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