Progressive study of the effect of superfine green tea, soluble tea, and tea polyphenols on the physico-chemical and structural properties of wheat gluten in noodle system.

In this study, the improving effects of green tea powder, soluble tea, and tea polyphenols on the mixing and tensile qualities of dough and texture of tea-enriched noodles, as well as the physico-chemical and structural properties of gluten proteins were progressively investigated. Dough strength and noodle texture were significantly increased by all the three tea products. Tea polyphenols in particular presented the most effective improvement with highest dough stability, resistance, and noodle chewiness. SEM indicated that tea products all induced a more developed gluten network, and polyphenol noodle showed the most continuous and ordered structure. FT-IR and fluorescence spectrum indicated that tea polyphenols promoted an enhancement in α-helix structure and the hydrophobic interactions. Tea polyphenols induced the SH/SS interchange during processing and cooking, and enhanced the water-solids interaction in noodles. AFM results showed that polyphenols induced the polymerization of gluten protein molecular chains, with increased chain height and width.

Inhibiting effect of low-molecular weight polyols on the physico-chemical and structural deteriorations of gluten protein during storage of fresh noodles.

In this study, the inhibiting effects of low-molecular weight polyols on the deterioration of gluten network and noodle texture were systematically investigated, based on dough rheological properties, and the macroscopic, structural and water status changes of gluten protein during storage of fresh noodles. Both glycerol and propylene glycol significantly restrained the decrease of GMP gel weight, LA-SRC value, hardness and springiness, and the increase of cooking loss. SEM showed that polyols retarded the collapse of gluten network, with still continuous gluten fibrils. The inner structure of polyol noodles was much less damaged after 2 days, with more uniform moisture distribution in MRI images. Potential dynamic depolymerization and repolymerization interactions were detected for protein components during processing and cooking, which might contribute to the textural changes. Low-molecular weight polyols inhibited the collapse of gluten network and deterioration of noodle texture although they showed no inhibiting effect on microbial growth.

Comparative study of the quality characteristics of fresh noodles with regular salt and alkali and the underlying mechanisms.

The quality properties of fresh noodles with NaCl and alkali were characterized by rheological, cooking, and texture properties. Microstructure, starch viscosity, protein conformation, gelatinization and protein polymerization during cooking, and water status were determined to investigate the mechanisms underlying their quality differences. The results showed that alkali induced more significantly increased (P < .05) gluten strength and noodle hardness, while NaCl resulted in superior dough extensibility. Pasting viscosity of alkali-flour increased and protein conformation changes were detected in alkaline noodles with increased ß-sheet and decreased α-helix structures. Both NaCl and alkali increased cooking loss. NaCl induced a fibrous gluten structure while alkali caused a membrane-like structure. Furthermore, remarkable protein aggregates were observed in alkaline noodles immediately after 2 min of cooking in non-reduced HPLC patterns, while 4 min in reduced patterns. Water-solids interaction in alkaline noodles was enhanced with decreased water mobility. NaCl induced no significant changes in protein aggregation and water status.