Effect Of The Interaction Between Tea Polyphenols And Wheat Gluten On Fresh Noodle Quality

As a main kind of traditional and staple food, noodles are consumed enormously in China for thousands of years. Though dry noodles own low water and long shelf-life, they are rehydratable food, whose taste is not good enough. fresh raw noodles, which are fresh and refreshing, have enough fragrance of noodles and remedy the disadvantage of dry noodles. However, the problems of single variety and short shelf-life limit the industrial production of fresh raw noodles. Adding tea polyphenols into fresh raw noodles, the various production of fresh raw noodles are realized and their healthcare function is improved.At the same time, their shelf-life is extended. This article aims at studying the interation between tea polyphenols and gluten in noodles according to the changes of quality, microstructure, secondary structure of gluten and the content of tea polyphenols, then exponds the effect of the interaction on quality of noodles and tries to discuss the effect mechanism of tea polyphenols on quality of noodles at the molecular level.Tea polyphenols were added into fresh raw noodles in addition of 0.3%, 0.6%, 0.9% and 1.2%. With the increasing of the addition, the formation time and the stability time of the dough increased; L* decreased and the colour of the dough was a little yellow; the pulling strength, hardness and chewiness of cooked noodles increased gradually. When the addition of tea polyphenols was 1.2%, the pulling strength decreased a little and the hardness and chewiness decreased observably. When the addition of tea polyphenols was 0.9%, the softness was the lowest; the pulling strength, hardness and chewiness were the best; the shelf-life of the noodles was extended from 9.1d to 17.0d in the storage of 4℃. Therefore, the optimal addition of tea polyphenols was 0.9%.When the addition of tea polyphenols was 0.9%, the content of the gliadin and GMP in the noodles decreased slower than the blank. And the content of disulfide bond in GMP was higher than the blank. At the early storage, α-helix and β-turn changed to β-sheet.But six days later, β-fold changed to β-turn in turn.After separating catechins from tea polyphenols by the method of HPLC, the content of each catechin was obtained. The content of EGCG was 62.01%, ECG was 11.33%, EC was 6.27%, C was 1.43%. The catechins in noodles were dectected and the results showed that the content of C, EGC and ECG changed little, EC decreased obviously in early six days, then keeped changeless, and EGCG decreased continuously.After mixing proteins with catechins by the rate of 1:6(EGCG:HMW-GS)、1:50(EGCG:LMW-GS)、1:56(EC:HMW-GS)、50:1(EC:LMW-GS)according to the rates they were in noodles, 4.88% of EGCG and 33.15% of EC was absorbed by HMW-GS. 74.65% OF EGCG and 34.94% of EC was absorbed by LMW-GS. This result showed that the main protein which interacted with EGCG was LMW-GS. EC had important effect on both the two proteins. But EC had effct of protection and bacteriostasis on the gluten just at the storage of early six days.Mixed with EGCG, the content of β-sheet and random coil of HMW-GS increased 8.0% and 0.4%, and α-helix and β-turn of HMW-GS decreased 0.7% and 7.1%, separately. The content of β-sheet and random coil of LMW-GS decreased 4.5% and 0.1%, and α-helix and β-turn of LMW-GS increased 0.5% and 4.2%, separately. Mixed with EC, the content of β-sheet and α-helix of HMW-GS increased 6.0% and 1.3%, β-turn and random coil of HMW-GS decreased 6.6% and 0.7%, separately. The content of α-helix and β-turn of LMW-GS increased 0.5% and 6.1%, and β-sheet and random coil of LMW-GS decreased 5.6% and 0.1%, separately. Both EGCG and EC changed the conformation of HMW-GS and LMW-GS.