Effects of γ-polyglutamic acid on the rheological, microstructural and sensory properties of low-fat yogurt

BACKGROUND: While low-fat yogurt offers numerous health benefits, its texture and sensory qualities are poor. This study aimed to investigate the effects of gamma-polyglutamic acid (gamma-PGA) on the rheological, microstructural and sensory properties of low-fat yogurt using rheological tests, scanning electron microscopy (SEM) and sensory evaluation. RESULTS: The results showed that the syneresis of low-fat yogurt added with 0.15% gamma-PGA was significantly (P < 0.05) reduced to 23.03%, compared to that of low-fat yogurt without gamma-PGA (42.87%). An improvement in storage and loss moduli (G', G") and apparent viscosity was also observed. The power law model fitted to rheological data indicated that gamma-PGA enhanced the viscoelasticity and strength of the gel network though interaction with casein gel, which might lead to changes in the moduli of yogurts. Microstructural observation via SEM confirmed the enhanced crosslinking between casein micelles and the filling effect of gamma-PGA. Sensory liking scores were strongly correlated with rheological properties and apparent viscosity. The results of principal component analysis (PCA) confirmed the positive effects of gamma-PGA on quality and rheological attributes of low-fat yogurt. CONCLUSION: The results of this study provided valuable references for the potential use of gamma-PGA as a fat replacer to stabilize the sensory quality of low-fat yogurt. (c) 2024 Society of Chemical Industry.