Microstructure of Yogurt Stabilized with Milk Proteins

Abstract

Skim milk yogurts were stabilized with a variety of casein- and whey protein-based ingredients. Experimental yogurts contained 1.5% added protein and were compared to a reference yogurt prepared with .5% gelatin (225 Bloom strength).Scanning and transmission electron microscopy revealed extensive fusion of casein micelles in yogurts prepared with additional casein. Yogurt prepared with skim milk powder and milk protein concentrate were composed of casein micelle chains held together by short links. Sodium caseinate induced formation of large and extensively fused micelles.Yogurts prepared with three types of commercial whey protein concentrate were similar in structure but differed distinctively from casein-based yogurts in that casein micelles were individual in nature with intermicellar spaces spanned with flocculated protein.