Improved flavor characteristics of soy protein hydrolysates are needed so that soy protein ingredients with valuable properties can be used in food applications. The primary objective of this research was to evaluate the aroma and flavor alteration of soy protein hydrolysates using descriptive analysis (DA). Data were analyzed using analysis of variance and differences were determined (p\u3c0.05). Sensory panelists (12) described differences in extruded-expelled soy flour (EESF) hydrolysates, particularly fishy, nutty, toasted, sweet, grassy beany, raw beany, bitter, and astringent attributes. Greater fishy aroma was detected in jet-cooked treatments of EESF compared to uncooked treatments. Control and Multifect-Neutral (MN)-modified EESF samples were more fishy than bromelain and Experimental Exopeptidase-C (EEC) treatments. For flavor attributes, bromelain hydrolysate was no different than the control. EEC and MN treatments had less sweetness and more intense grassy-beany flavor, astringency and bitterness than the control. MN-modified EESF was the most bitter and had the least nutty and toasted flavors among samples. A trained panel (10) evaluated sweetness and bitterness of EESF treated with MN and alpha-galactosidase (alpha-GAL). The non-digestible sugar in EESF hydrolyzed by alpha-galactosidase (alpha-GAL) increased sweetness and decreased bitterness of MN-modified EESF. alpha-GAL modification could be used to mask the bitterness of soy protein hydrolysates. Eleven trained panelists evaluated 3 protease-modified soy protein isolates (SPI) samples and un-hydrolyzed control with high- and low-protein dispersibility indices (PDI). High- and low-PDI SPIs were similar in most of the sensory attributes, but low-PDI SPI had more raw beany and bitter flavors than high-PDI SPI. SPI and soy flour hydrolyzed by MN were the most bitter and astringent and lowest in sweetness than other enzyme treatments. FPC-modified SPI had higher cooked beany flavor, less bitter flavor and less astringency than MN-modified SPI and the control. MN+FPC treatment had the sensory attributes between the single enzyme treatments. \u22Cooked beany\u22 was a single attribute defined by sensory panelists, but is likely a mixture of aromas and flavors attributed to by-products of nonenzymatic browning and fatty acid oxidation, volatile carbonyls from lipid oxidation and furans. Proteolysis modification reduced chalkiness and grittiness of soy protein, which would be a favorable attribute for beverages. Bitterness and astringency are the primary flavor problems of protein hydrolysates. Bromelain and FPC proteases produced soy protein hydrolysates with little bitterness and may be potential hydrolysates for food applications. The use of MN + alpha-GAL and the MN + FPC combinations produced less bitter soy hydrolysates than the MN treatment alone.
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