PRODUCTION OF LOW-FAT AND NONFAT SET-STYL E YOGURT WITH WHEY-PROTEIN PRODUCTS AND ROPY STRAINS

The study deals with the influence of two functional whey protein prod ucts on gel firmness, susceptibility to syneresis and sensory properti es of set-style fat-reduced yogurt. Fermentation resulted from differe nt ropy and non-ropy strains of yogurt starters. Despite minor increas es in dry matter contents, the addition of the special whey protein pr oducts led to a qualitative upgrading, especially of low-fat yogurt, b eing superior to samples only made with added skim milk powder. Howeve r, from the sensory point of view, protein products are hardly able to replace milkfat. Acidification with ropy strains of yogurt cultures i s well suited to improve mouthfeel of fat-reduced yogurt by producing exopolysaccharides. In combination with 0.7 resp. 1.0 % (= 0.35 % prot ein) whey protein product a culture with medium slime production achie ved the best results. Comparative measurements of gel firmness and whe y separation demonstrated that the tatter parameter appears better sui ted to allow conclusions on the mouthfeel of the corresponding yogurt sample.