New insights into how starch structure synergistically affects the starch digestibility, texture, and flavor quality of rice noodles.

The functionalities of gluten-free rice noodles are significantly affected by starch hierarchical structures. Identifying the structures that synergistically determine noodle integrated functionalities is vital to designing health-promoting starchy foods with desirable consumer sensory and nutritional qualities. This study reports on the changes in starch structures and functionalities (starch digestibility, texture, and flavor) of rice noodles during household cooking processes (steaming, boiling, and stir-frying), and describes an underlying structure-functionality relationship. Results show that all the cooking processes examined increased starch reassembled ordered structures, especially short-range ordered structures, helical and crystalline structures, and ordered aggregate structures. Steaming and boiling led to a decrease in rapidly digestible starch (RDS) and an increase in slowly digestible starch, while stir-frying yielded a reduction in RDS content and an increase in resistant starch in rice noodles. Steaming and boiling decreased while stir-frying increased the flavor variety of noodles. All cooking processes examined altered noodle textures, with a significant increase in hardness, gumminess, and chewiness. Structure-functionality relationships suggested short-range ordered structures, crystalline structures, and the ordered molecular and aggregate structures of noodles synergistically determined starch digestion, texture, and flavor. By structuring such key structures, the digestion, texture, and flavor of rice noodles can thus be reasonably controlled.

Polysaccharide extracted from the leaves of Cyclocarya paliurus (Batal.) Iljinskaja enhanced stress resistance in Caenorhabditis elegans via skn-1 and hsf-1.

Cyclocarya paliurus polysaccharide (CPP) has many beneficial biological activities. Although the antioxidant activity of CPP is well-known, the stress tolerance and underlying mechanism of the activities of CPP have not been determined in vivo. In this study, we applied the emerging model of Caenorhabditis elegans (C. elegans) to observe that CPP imparted stronger resistance to stress than the positive control Astragalus polysaccharide (H2O2- and paraquat-induced oxidative stress, as well as heat stress) without threatening the growth and reproduction of worms. Further studies found that CPP-treated worms had a strong antioxidant defense system that downregulated peroxidation products (ROS, MDA, NEFAs and GSSG) and upregulated antioxidant enzymes and nonenzymatic activities (SOD, CAT, GSH-Px and GSH). The CPP-treated worms also exhibited improved physiological functions, such as inhibition of age pigment and improvement of lifespan, mobility and neuroprotection. Further exploration of the mechanism of action of CPP treatment suggested that increased resistance to CPP might activate stress-inducible genes (sod-3, sod-5, ctl-1, ctl-2, hsp-16.1 and hsp-16.2) via skn-1 and hsf-1, rather than daf-16. These findings suggest that CPP may have health benefits for humans.