Effects of Tea Polysaccharides on the Quality and Digestive Properties of Fresh Wet Rice Noodles: Multivariate Analysis and Mechanistic Insights

Traditional fresh wet rice noodles (FWRNs) have shortcomings such as low nutritional value and poor edible quality. Tea polysaccharides (TPSs) show great potential in the food industry as a product with multiple biological activities. Therefore, this study investigated the effects of TPSs on the physicochemical properties and digestive characteristics of FWRNs. Results showed that TPSs significantly reduced the viscosity (p < 0.05) and inhibited the short-term retrogradation of rice flour. TPSs also enhanced the edible qualities (cooking loss, breaking rate, hardness, adhesiveness, and chewiness) of FWRNs. X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy jointly revealed that TPSs improved the ordered structure of starch. The relative crystallinity increased by 2.79%, and the short-range order also improved. Polysaccharides reduced the contact points of starch with enzymes during the digestion process and affected the digestion of starch. In vitro digestion data indicated that TPSs contribute to reducing starch hydrolysis rate. Notably, at a TPS addition level of 2%, resistant starch (RS) content increased by 8.61% and rapidly digestible starch (RDS) decreased by 7.48%, while slow digestible starch (SDS) showed minimal change. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) revealed that TPSs altered the starch cross-linking network. TPSs enhanced the antioxidant capacity of FWRNs, increasing DPPH and ABTS radical scavenging by 89.25% and 59.58%, respectively. Multivariate analysis further revealed relationships among the quality characteristics of FWRNs. This study provides a reference for optimizing functional rice noodles products.