Matcha-fortified rice noodles: Characteristics of in vitro starch digestibility, antioxidant and eating quality

Matcha (MT), the finely ground powder of green tea leaves, is increasingly used as a nutritional food ingredient due to its large content of polyphenols. In this work, rice noodles were fortified with 0, 0.5, 1.0, 1.5 and 2.0% (w/w) of MT, and assessed for in vitro starch digestibility. Addition of MT significantly (p < 0.05) decreased rapidly digestible starch (74.97-62.59%), increased resistant starch (7.56-25.94%), and decreased the glycemic index (84.78-68.34). MT gifted the rice noodles with higher antioxidant capacity and volatiles ((E)-2-hexenal, butyl acetate, 6-methyl-5-heptan-2-one and limonene). After gastrointestinal digestion, the polyphenols retention rate was as high as 57.84%. Furthermore, CLSM revealed that MT polyphenols-starch-protein interactions could interfere with the reassociation of starch chains, leading to the formation of low-ordered crystalline structures (confirmed by DSC, XRD and FT-IR), and the formation of a dense microstructures as revealed by SEM. Thus, rice noodles were endowed with lower cooking losses, higher chewability and stretchability. This work demonstrated the potential use of MT as food ingredient to improve the nutritional properties and eating qualities of rice noodles.