Incorporation of water-in-oil-in-water (W1/O/W2) double emulsion in a set-type yogurt model

Abstract

The effect of W₁/O/W₂ emulsion incorporation in set-type yogurt on the acidification process, physicochemical properties, bacterial growth kinetics and structural characteristics was investigated. The W₁/O/W₂ emulsion was formed by using a two-step homogenisation process and milk as the W₁ and W₂ phases, and stability was monitored with optical microscopy and cryo-SEM. Adding the W₁/O/W₂ emulsions reduced the acidification rate, viscosity and water retention capacity. Texture (adhesiveness, cohesiveness, hardness, and gumminess) differed in yogurts containing W₁/O/W₂ emulsion compared to controls during the acidification process, however, trends became stable during storage. The growth of S. thermophilus during the acidification process of yogurt was reduced in the presence of W₁/O/W₂ emulsion while L. bulgaricus trended higher during storage. This study shows that yogurts containing W₁/O/W₂ emulsion are feasible subject to processing modification.

Keywords: Acidification; Lactobacillus bulgaricus; Streptococcus thermophilus; W(1)/O/W(2) double emulsion; Yogurt.