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P. M. COLAHAN-SEDERSTROM and D. G. Peterson. Dept. of Food Science, Pennsylvania State Univ., 215 Borland Lab., University Park, PA 16802 A common problem associated with thermal processing of many food/beverage products is the simultaneous generation of flavor/off-flavor compounds that ultimately result in the development of negative product traits. For example, ultra-high temperature (UHT) processed milk has a cooked flavor that is often considered a flavor defect. Recently our research group has reported that flavonoids, such as epicatechin (EPC), can be used to inhibit the thermal generation of aroma compounds. Our objective was to evaluate the ability of epicatechin (EPC) to inhibit the thermal development of aroma compounds formed during UHT milk processing. Whole raw milk (control) and whole raw milk with three different levels of EPC (0.01, 0.1 and 0.2%) were processed under UHT conditions (138ºC for 6 seconds). Aroma isolates of the control UHT milk and the UHT milk with 0.1% EPC were prepared by solvent assisted flavor evaporation (SAFE) and subjected to Aroma Extract Dilution Analysis (AEDA) to determine differences in key aroma compounds. Key compounds were identified via their linear retention indices on two columns of different polarity, mass spectra, and odor characteristics. A trained sensory panel was also used to evaluate the intensity of cooked flavor in the control and three treatment samples as well as a commercial pasteurized milk sample for comparison. The AEDA indicated that addition of EPC prior to UHT processing of raw fluid milk reduced the overall thermal formation of key aroma-active compounds (i.e. 2-acetyl-1-pyrroline, 2-acetyl-2-thiazoline, skatole, o-aminoacetophenone and methional) in comparison to the control UHT milk. Furthermore, the sensory evaluation showed that all treatment samples had statistically (P<0.05) lower cooked flavor in comparison to the control, while the 0.2% EPC sample was statistical similar to pasteurized milk sample. These results indicate that flavonoids (i.e. EPC) can be used to control the formation of thermally induced aroma compounds during heat processing.
Session 94, Food Chemistry: Chemical effects of food processing, preservation and formulation
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