Previous studies have shown that emulsions with higher solid fat content (SFC) are related to a higher in-mouth coalescence level and fat-related perception. However, the effect of SFC in fat droplets on the fat-related attributes of emulsion-filled gels has not been fully elucidated. In this study, the effect of SFC on the creamy mouthfeel of acid milk gel was investigated. Five kinds of blended milk fats with SFC values ranging from 10.61% to 85.87% were prepared. All crystals in the blended milk fats were needle-like, but the onset melting temperature varied widely. Blended milk fats were then mixed with skim milk to prepare acid milk gels (EG10–EG85, fat content 3.0%). After simulated oral processing, the particle size distribution and confocal images of the gel bolus showed that the degree of droplet coalescence in descending order was EG40 > EG20 > EG60 > EG10 ≥ EG85. There was no significant difference in apparent viscosity measured at a shear rate of 50/s between bolus gels, but the friction coefficients measured at 20 mm/s by a tribological method were negatively correlated with the coalescence result. Furthermore, quantitative descriptive analysis and temporal dominance of sensations analysis showed that SFC significantly affected the ratings of melting, mouth coating, smoothness and overall creaminess, as well as the perceived sequence and the duration of melting, smoothness and mouth coating of acid milk gels. Overall, our study highlights the role of intermediate SFC in fat droplets on the creamy mouthfeel of acid milk gels, which may contribute to the development of low-fat foods with desirable sensory perception.

Lactic acid bacteria exopolysaccharides (LAB EPS) have garnered significant interest owing to their beneficial biological properties and safety. This study aimed to screen LAB EPS with comprehensive biological activities and anti-allergic potential from four high-yield strains, isolate and characterize their homogeneous polysaccharide fractions, and preliminarily explore their anti-allergic mechanism. Through in vitro evaluation of antibacterial, hyaluronidase inhibitory, antioxidant and immunomodulatory activities, Lacticaseibacillus casei LZ9183 EPS (183 EPS) was identified as the optimal candidate with the most superior comprehensive performance. Further purification via DEAE-52 anion exchange chromatography and Sephadex G-100 gel filtration chromatography yielded two homogeneous polysaccharide fractions, LZEPS-1 and LZEPS-2. Structural characterization results showed that LZEPS-1 (28.73 kDa) was a neutral polysaccharide composed of rhamnose, galactose, glucose and mannose with a total sugar content of 94.39 ± 0.92%, while LZEPS-2 (95.58 kDa) was an acidic polysaccharide containing glucose, galactose, arabinose, mannose, xylose and glucuronic acid with 92.17 ± 1.22% total sugars and 1.72 ± 0.04% protein. Using the RBL-2H3 cell degranulation model, we demonstrated that 183 EPS, LZEPS-1 and LZEPS-2 effectively alleviated IgE-mediated allergic responses by inhibiting the release of β-hexosaminidase and histamine, and modulating the secretion of IL-4 and TNF-α to restore the Th1/Th2 balance. These results propose that LAB EPS could potentially be utilized as natural anti-allergic functional ingredients in the development of functional foods or dietary supplements.