Comparison of the Aroma Characteristics of Acid-Hydrolyzed and Enzyme-Hydrolyzed Vegetable Proteins Produced from Soy

The aroma volatiles of an acidic hydrolyzed vegetable protein (HVP) and an enzymatic hydrolyzed vegetable protein (EVP) were compared by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GCO). Major differences were found between the two hydroly-sates. Furans and furanones, pyrroles, and sulfur-containing compounds were mainly present in HVP, whereas alcohols (including phenols) and pyrazines were mainly found in EVP. These differences reflected the two production methods. The high temperature and low pH during the acid hydrolysis of HVP favored the production of furans and the decomposition of sulfur amino acids, resulting in the production of sulfur-containing volatile compounds. A pH above 5 during the enzymatic hydrolysis facilitated the production of pyrazines. The alcohols in EVP may be formed by the added enzymes or by enzymes naturally present in the soy grits. Significant differences in the odors between the hydrolysates were detected by GCO.