SOLUBILITY AND EMULSIFYING PROPERTIES OF SOY PROTEIN ISOLATES MODIFIED BY PANCREATIN

Soy protein isolates (SPI) with varying degrees of hydrolysis (DH of 7 , 11, 15, 17%) were produced using pancreatin. The surface hydrophobic ity indices of pancreatin hydrolyzed SPI (PSPI) (34.5, 34.9, 39.1, and 40.7 for 7, 11, 15, 17% DH, respectively) were higher than that of SP I (10.5) and control SPI (CSPI) (12.5, 11.9, 12.9, and 12.6 for 10, 60 , 120, and 180 min incubation, respectively). The solubilities of PSPI at pH 4.5 were 2.7, 9.1, 11.9, and 18.7%, for 7, 11, 15, and 17% DH, respectively while the solubilities of SPI and CSPI at the same pH wer e about 1.6%. Solubilities of PSPI at pH 7.0 were > 90% for all DHs te sted, while those of SPI and CSPI were 85%. The emulsifying activity i ndex (EAI) of PSPI increased with increasing DH. PSPI with 15% DH had highest EAI (1.122) which was higher (P < 0.05) than those of SPI (0.5 50) and CSPI after 120 min incubation without enzyme (0.568). These re sults suggest that PSPI could be used as an ingredient for emulsified products and where high solubility at low pH is required.