Rheological properties of xanthan-modified fish gelatin and its potential to replace mammalian gelatin in low-fat stirred yogurt

Fish gelatin (FG) has been modified to replace mammalian gelatin, but has not been applied in the yogurt production. In this study, xanthan gum (XG) was used to improve the rheology properties of FG, and the XG-modified FG was applied in acid milk gels and low-fat yogurts to mimic the rheology and texture properties of porcine gelatin (PG). No obvious difference in the storage moduli was observed for the FG gels (2.5 g/100 g) with the addition of XG from 0 to 0.05 g/100 g, while increasing addition of XG increasingly impeded the gelation process of FG. Moreover, in the milk gel system with FG addition (0.4 g/100 g), an increase in the XG proportion caused an increase in the storage moduli. Milk gels with a XG to FG ratio of 1:99 best mimicked the storage moduli of milk gels with PG. In the yogurt system, yogurt with 0.4 g/100 g XG-modified FG had better water-holding capacity and consistency than the yogurt with 0.4 g/100 g PG, and had similar viscosity, pseudoplasticity, and thixotropy to yogurt with 0.4 g/100 g PG. The results suggested that XG-modified FG is a promising replacement for mammalian gelatin in low-fat stirred yogurt.