Effects of Adding Wuyi Rock Tea on Quality, in vitro Digestive Characteristics and Antioxidant Activity of Rice Noodles

In order to develop functional rice flour products with anti-digestive and antioxidant activities, the effects of adding Wuyi rock tea (WRT) on the quality, in vitro digestive characteristics and antioxidant activity of rice noodles were studied. The texture and sensory quality of rice noodles were determined by texture analyzer and sensory evaluation method, respectively. The flavor components were characterized by GC-MS, and the antioxidant activity was assessed by FRAP, DPPH and ABTS⁺ assays. The digestive characteristics of rice noodles were detected by the in vitro simulated digestion method. The results showed that compared to the control rice noodles, the breaking rate of rice noodles added with 2.9%~7.0%. WRT was not significantly changed (P>0.05), while the breaking rate of rice noodles added with 8.3% WRT was significantly increased (P<0.05). Adding 2.9%~8.3% WRT could significantly lower the values of hardness, cohesiveness, gumminess, chewiness and resilience of rice noodles (P<0.05), but improve the smell and taste scores of rice noodles (P<0.05). The rice noodles added with 5.7% WRT had the highest springiness value among all the groups and reserved the main volatiles from rock tea (i.e. 2,6-Octadien-1-ol, (Z)-3,7-dimethyl, 2-phenylethanol, benzeneacetaldehyde, (E)-2-Hexenal). Meanwhile, it was found that adding 5.7% WRT could reduce the proportion of fast digestible starch of rice noodles by 8.69%, while increase the proportion of resistant starch by 14.34%. In addition, compared with the control noodles, the rice noodles added with 5.7% WRT had a considerably stronger ability to scavenge DPPH and ABTS⁺ free radicals (P<0.05), with a total antioxidant capacity of 7.48 times that of the control noodles. The results suggested that the addition of WRT provided rice noodles with a unique flavor, higher digestion resistibility as well as antioxidant activity, thus improving the nutritional and healthy properties of rice noodles.