The absence of lipoxygenase and 7S globulin of soybeans and heating temperatures on the properties of soymilks and soy yogurts

Abstract

The aim of this study was to produce soy yogurt and investigate the physicochemical, textural, and volatile flavor compounds, as well as sensory characteristics using normal (NOR), lipoxygenase-lacking (LOX-lack), and 7S-globulin lacking (7S-lack) soybeans at different temperatures. The soy yogurts were produced by Streptococcus thermophilus and Lactobacillus delbruekii subsp. bulgaricus fermentation of the soymilk. SDS-PAGE results showed that the globulin, subunit, and polypeptide contents of soymilk were affected significantly by the absence of LOX and 7S. Heat treatment accelerated the protein aggregation of soymilk but the content of large non-disulfide aggregates was lower for LOX-lack than for NOR and 7S-lack. As a consequence, the gel firmness and storage modulus of LOX-lack soy yogurt were the highest among others during the heat treatment (80–115 °C), and its network structure was the most compact under CSLM observation. The LOX-lack soy yogurt had the lowest off-flavor compounds and the best sensory acceptability, which offered the best potential for producing soy yogurt with improved textural and volatile profiles.