The Impact of Technological Factors on the Air Phase of Defrosted Fermented-Milk Desserts

Whipped desserts made of fermented milk are very popular. They also make it possible to expand the range of functional products. The consumer properties of defrosted desserts depend on the air phase. This research featured the impact of different formulations and methods on the dispersion of the air phase in the process of defrosting fermented-milk desserts. The study featured several samples of whipped fermented desserts. Sample 1 contained gelatin; Sample 2 contained pectin. Samples 1 and 3 had different contents of fermented foundation while Samples 3 and 5 differed in the amount of gelatin stabilizer. Sample 4 contained a whey protein concentrate. The dispersion of structural elements was measured using microstructural methods. The experiments included the quality parameters of mixes, as we ll as the dispersion of air phase in the frozen state and after 24 h of storage at 4 ± 2°C. The viscosity of the sample with pectin exceeded that with gelatin by 3.8 times. Extra whey protein increased the viscosity by 4.4 times and the overrun – by 1.4 times. In the whey protein sample, the average diameter of air bubbles was 36 μm after 24 h of storage at 4 ± 2°C and 50 μm after 12 months, while in the sample without protein it was 48 and 86 μm, respectively. Sample 3, which had a greater fermentation, demonstrated a smaller average diameter of air bubbles (by 21 μm) after 24 h of storage than the sample with yogurt. The sample with extra gelatin increased the overrun by 1.3 times and negatively affected the dispersion of the air phase. After 24 h of storage, the average diameter of the air bubbles in the sample with an increased content of stabilizer was higher by 27 μm. The air phase was less stable in the sample with pectin. The research established the effect of gelling agents, whey protein concentrates, and fermented foundation on the dispersion and stability of the air phase in fermented-milk desserts. Pectin appeared to have a negative effect on the air phase during defrosting and caused excessive condensation and drainage. The increasing amount of fermented base and gelatin, as well as the use of whey protein concentrates, increased the stability of the air phase during 24 h of storage at 4 ± 2°C. The research results could be used to develop new production technologies of overrun fermented desserts and their preservation in the defrosted state.