Preparation of Tea Polyphenol-Soy Protein Isolate Microspheres and Their Effects on Low-fat Emulsified Sausage

This study focused on developing a low-fat emulsified sausage by using tea polyphenol-soy protein isolate microspheres as a fat substitute. Tea polyphenol- soy protein isolate microspheres were prepared by thermal cross-linking at 80 ℃ through a reverse-phase emulsion. The microsphere's morphology and diameter were characterized by fluorescence microscopy, confocal laser scanning microscopy, and scanning electron microscopy. In vitro experiments simulated gastrointestinal digestion to investigate the release kinetics of tea polyphenols from the microspheres. The microspheres were then used to replace fat in the preparation of low-fat emulsified sausages. The texture and storage stability of the low-fat sausages were evaluated, and sensory assessments were conducted on appearance, mouthfeel, texture, flavor, and acceptability. Results showed that at 120 min in gastric juice, the microspheres released about 20% of the tea polyphenols, with the release rate increasing to 60% in intestinal juice, which demonstrated good intestinal responsiveness. The low-fat sausages, when compared to full-fat sausages without microspheres, showed no significant difference in hardness, cohesiveness, elasticity, adhesiveness, and chewiness (P>0.05). They also maintained similar flavor components, indicating preserved texture and taste. Moreover, the shelf life of the low-fat sausages was extended by approximately 14 days, with microbial tests showing colony counts well below national standard limits. Overall, the plant-based gel fat substitute can be used as an effective fat alternative. It has great potential in developing low-fat, healthy emulsified sausages with texture and flavor qualities comparable to those of full-fat products and a broad application in low-fat foods.