Effects of mulberry pomace polysaccharide addition before fermentation on quality characteristics of yogurt

Mulberry pomace, a by-product of mulberry juice processing, is rich in natural bioactive substances including polysaccharides and polyphenols and is useful for the production of functional foods. As such the effects of mulberry pomace polysaccharide (MPP) on physicochemical, textural and microstructural features of yogurt during cold storage were investigated. MPP was incorporated into reconstituted skim milk at 0% (control), 0.5%, 1.0% and 1.5%, respectively and then fermented to yogurt and stored at 4 °C for 28 days. The color, pH, titratable acidity, syneresis, rheology, texture and microstructure of yogurt samples were analyzed. The addition of MPP before fermentation dose-dependently affected the pH value and titratable acidity of yogurt samples such that the addition of 0.5% MPP showed the most significant effect in reducing syneresis, increasing gel strength and viscosity, and improving texture and microstructure of yogurt. The results indicate that the appropriate amount of MPP can effectively improve the gel properties and physicochemical parameters of yogurt, and MPP played an important role in the yogurt quality improvement by mulberry pomace.