Consequences of vacuum evaporation on physicochemical properties, storage stability and in vitro digestion of fermented goat milk

Abstract

Concentrated goat milk products are attracting more and more attention in the food industry. This research was performed to investigate the effects of different levels of vacuum evaporation concentration pretreatment on the physicochemical characteristics and in vitro digestion of fermented goat milk (FGM). Concentrated FGM showed higher contents of protein, fat and total solids, longer fermentation time, higher viscosity, increased yellowness vision and enhanced texture characteristics, while exhibited smaller average casein micelle sizes compared to pristine FGM samples. Meanwhile, concentration pretreatment improved the titratable acidity, water holding capacity, emulsion and microbial stability of concentrated FGM as compared with unconcentrated control during 21 days of storage at 4 °C. Principal component analysis showed that the overall quality improvement of FGM was greatest at a concentration gradient of 25% (v/v). FGM with higher concentration gradient exhibited lower protein digestibility and degree of hydrolysis, while higher antioxidant capacities at the end of gastrointestinal digestion than those of control. Heatmap further suggested that CFGM showed better physicochemical and organoleptic characteristics than unconcentrated FGM. This study provided a theoretical reference for industrial processing of novel FGM products with compacter structure, better storage stability, stronger antioxidant capacity and higher consumer's acceptability by vacuum-assisted evaporative concentration.