Effects of Lycium barbarum on gluten structure, in vitro starch digestibility, and compound noodle quality

Abstract

Lycium barbarum, a plant of the Solanaceae family with medicinal and food origins, is rich in many bioactive substances. This study examined the effects of Lycium barbarum pulp (LBP) on the gluten structure, starch digestibility, and compound noodle quality. The addition of LBP (typically less than 5%) could improve the performance and structure of gluten proteins. Compared with the control group, when LBP addition was 5%, Tp and ΔH increased significantly (p < 0.05), and the stability of gluten protein thermal increased. At this time, LBP also had a certain reduction effect on the surface hydrophobicity (from 0% to 5%), and the concentration of free thiol group increased from 1.93 μmol/g to 4.19 μmol/g. In addition, the LBP addition improved the gluten structure resulting in favorable texture, stretchability, cooking properties, and flavor of noodles. The hardness and recovery significantly increased by about 25.97% and 11% (p < 0.05), and the cooking yield and cooking loss also changed significantly (p < 0.05). More than 5% of an addition was reported to exhibit detrimental effects. The addition of LBP greatly reduced the in vitro starch digestibility and the expected glycemic index (p < 0.05). The scanning electron microscope (SEM) and atomic force microscope (AFM) analysis showed that the bioactive components of LBP can mix with gluten protein, bringing the structure of noodles closer together and intensifying the cross-linking of the gluten structure. Our results indicated that gluten protein and the starch-gluten composite system were overall improved by LBP addition, while the starch digestibility was lowered.