Study on the effect of heat treatment process on the quality characteristics of soybean-Citri Reticulatae Pericarpium (CRP) based yogurt and related mechanisms

Abstract

To improve the quality of soy yogurt, three different heat treatment methods were studied for the preparation of soybean-Citri Reticulatae Pericarpium (CRP) based yogurt. This study investigated the effects of dry steaming (DS), baking-blanching (BB), and wet steaming (WS) on the physicochemical properties, texture, and flavor of yogurt, and explored the mechanism of affecting yogurt gel properties. At a solid-liquid ratio of 1:7, yogurts exhibited superior textural properties. GC-MS analysis revealed that all treatments effectively reduced the flavor components of beany, and CRP imparted dominant lemon and citrus aromas to yogurt. The yogurt produced by DS and WS treatment showed higher viscoelasticity and water stability. The results of fluorescence spectroscopy, FTIR, and SDS-PAGE indicated that DS treatment significantly unfolded the tertiary structure of proteins, making them more susceptible to enzymatic hydrolysis, leading to a higher proportion of disordered secondary structures and an increase in acidity of yogurt. The WS treatment produced yogurt showed the highest levels of α-helix and β-sheet structures, contributing to a gel system with enhanced stability. Analysis of intermolecular forces showed that the samples treated with DS had stronger hydrophobic interactions, while treatment with WS resulted in a higher content of disulfide bonds in yogurt to improve gel stability. Microstructure analysis demonstrated that the gel network of samples produced by the WS treatment was tighter, whereas yogurts produced by the other two treatments were less stable due to fat aggregates. This study provided critical technical support and theoretical foundations for improving the quality of soybean-based yogurt.