Modulating the Quality of Chinese Quince Slices via Vacuum Frying: Focus on Sensory Attributes, gut Microbiota After In Vitro Fermentation, and SCFA Production.

Fresh Chinese quince (Chaenomeles sinensis) is inedible because of its lignified texture and strong astringency. Vacuum-frying serves as an effective processing technique to overcome these utilization barriers. However, the effects of vacuum frying on the quality and, crucially, the gut-regulating potential of Chinese quince remain unclear. This study employed a full factorial design to investigate the effects of frying temperature (70-100 °C) and time (20-30 min) on the quality attributes of quince slices and evaluated their subsequent effects on gut health using in vitro digestion and fermentation models. The ideal vacuum frying condition was 80 °C for 20 min, which resulted in a final moisture content of 2.88%, the lowest crude fat content (14.85 ± 0.74%), enrichment of characteristic volatile compounds (aldehydes and alkanes), and the highest sensory score (90.18 ± 4.25). Furthermore, compared with fresh slices, vacuum-fried products retained more significant prebiotic potential during colonic fermentation. They positively modulated the gut microbiota community by notably increasing the relative abundance of beneficial genera, such as Bifidobacterium (genus), Coprococcus (genus), and Sutterella (genus), while suppressing the abundance of pathogenic taxa, such as Streptococcus (genus). Metabolically, the fermentation of these slices significantly promoted the biosynthesis of short-chain fatty acids (SCFAs), with the total content increasing from 11.57 to 25.40 mmol/L, primarily driven by the accumulation of acetic, propionic, and butyric acids. These findings provide insights for promoting the high-value utilization of Chinese quince resources; in particular, they lay a foundation for the development of functional snacks using Chinese quince.