Influence Of The Interaction Between Tea Polyphenols And Gliadin On The Quality Of Fresh Noodles During The Storage Period

With a long history in China,noodles have a large consumer market.Fresh noodles have virtues of convenient,tasty,fresh,and unique fragrance so as to welcomed by consumers.But its high water content and water activity make it decays rapidly,hindered its circulate on the market.As a safe and natural compound,tea polyphenols can not only increases the nutritional value of noodles,but also prolong its storage time.This article aims to study interactions between tea polyphenols and gliadins in noodles according to the changes of quality,content of tea polyphenols and secondary structure in gliadins,then elaborates the effect of interactions between tea polyphenols and gliadins on structure properties,cooking properties and total bacterial counts of noodles.Noodles of group A(addition of tea polyphenols and gliadins 0.9%+0?0.9%+0.3%?0.9%+0.5%?0.9%+0.7%?0.9%+1.0%,respectively)and group B(addition of gliadins 0.3%?0.5%?0.7%?1.0%,respectively)were prepared,the controls are noodles without addition.The result shows that: during the storage time,brightness,hardness,chewiness and pulling strength of noodles of both groups are decreased,while the total bacterial counts of noodles are increased;the brightness of group A are lower than the control group significantly and decreased as the gliadin content increased;the hardness,chewiness of noodles of group B are increase with the increase of gliadins added to noodles.For noodles of group A,the hardness,chewiness and pulling strength of fresh noodles are decreased and then increased with the increase of gliadins added to noodles,and noodles with 0.9% tea polyphenols and 0.5% gliadins is the lowest;total bacterial counts of noodles with 0.9% tea polyphenols is the lowest.Therefore,to the brightness,hardness,chewiness and pulling strength of noodles,the addition of tea polyphenols is better than tea polyphenols+ gliadins to the protection of noodles,and noodles with 0.9% tea polyphenols and 0.5% gliadins is the lowest.In the noodles of tea polyphenols groups,two groups(0.9% tea polyphenols and 0.9% tea polyphenols+ 0.5% gliadins)is measured on content and structure change of gliadins,additive free group as control.During the storage period of noodles,gliadins and disulfide bonds in gliadins was decreased,while those of tea polyphenols noodles decreased slower.The secondary structure(?-helix,?-sheet,?-turns and random coil)of gliadins are changes non-significantly.The proportion of ?-helix of gliadins in additive free group is the highest,it shows a reduce tendency at first and then rise,it was higher than noodles of tea polyphenols groups all over the storage time.The gliadins of controls noodles are ordering,and the noodles with 0.9% tea polyphenols is the most stable.Method of HPLC was established to detection tea polyphenols.The content of each catechins was obtained: EGCG 66.92%?ECG 9.73%?EGC 6.31%?EC 6.61% and C 0.73%.Content of catechins during storage remain unchanged,but it has a significantly reduction when compared with the tea polyphenols component in the original noodles.According to proportions of tea polyphenol with gluten and gliadin in noodles,disulfide bonds,binding rate,and secondary structure of gluten and gliadin were tested.The results showed that disulfide bonds of gliadins are decreased during the storage period,and gliadins with tea polyphenols has a higher content of disulfide bonds than the control group.The binding rate of tea polyphenols components with gluten was significantly higher than that of gliadin,the combination of EGC with gluten protein is the highest,EC takes the second place EGC combined with gliadin better than other components.Interaction between tea polyphenols with gluten in water environment is noticeable,changes of the secondary structure are apparent.The ?-helix ratio in gluten is increases and then decreases,the rest three kinds of secondary structure are increases and then decreases;secondary structures of gliadins changes little.Changes of secondary structure under the environment of phosphate-SDS buffer are not significant,however,structure of gliadins is stable.