Preparation Of Naan From Wheat Flour And The Influence Of Static Simulated Digestion On Gluten Proteins

Celiac disease(CD)is an T cell mediated disease in the genetically susceptible individuals after consumption gluten from wheat,barley and rye.Xinjiang is located in the northwest of China,where wheat is the staple food,and the population carrying high celiac disease susceptibility alleles DQB1*0201 may be at high risk of celiac disease.Naan has two thousand years of history in Xinjiang,and it is the most important staple diet in Xinjiang.Nang is traditionally produced by fermentation and baking of wheat flour with the advantages of low water content,easy to carry,easy to preserve.Although naan is the staple food in Xinjiang residents,there were no reported cases of celiac disease.Whether this is caused by gluten changes in food processing or gluten degradation by digestion in the human body is worth exploring.In this work,"Xindong 22" and "Bainongaikang 58" wheat cultivar were as materials to produce naan.Firstly,the sensory properties,physicochemical properties and the texture characteristics of the prepared naan were assessed,respectively.Then,the digested behavior of naan in the simulated gastrointestinal fluid of infants and adults were tracked in detail,and intestinal brush border membrane enzymes were added in the simulated digestion.Moreover,the effects of p H of gastric fluids and digested time on digestion of gluten in naan were investigated.Finally,the digestion products were analyzed by Tricine-SDS-PAGE,Western blotting,RP-HPLC,and the degree of hydrolysis and gluten content were tested by OPA method and R5 kit,respectively.The main results and conclusions are presented as follows.1.Two kinds of naan were produced from "Xindong 22" and "Bainongaikang 58" wheat cultivar.The physicochemical index and gluten content of flour from "Bainongaikang 58" named Henan flour was higher than that of the flour from "Xindong 22" named Xinjiang flour,and the similar results was found in the corresponding naan.Processing leads to loss of nutrients and reduced gluten content,and the anti-Glia-?9 immunoreactivity was weakened,suggesting that food process can reduce the celiac disease toxicity of naan.2.Regarding to in vitro simulation of gastrointestinal digestion in infants and adults,the simulated gastric and intestinal fluid have great influence on the proteins of molecular weight between 10~75 kDa.In the simulated gastric digestion,the macromolecular proteins were degraded into small molecular fragments below 60 kDa.The small molecular fragments increased continuously upon the extension of gastric digestion.Then the undigested protein fragments were decreased in the process of intestinal digestion.The results also showed that adults have a stronger ability to digest naan than infants,and the hydrolysis ability of wheat proteins in simulated intestinal fluid was stronger than that in the simulated gastric fluid.3.The simulated gastric fluid with different pH had a significant effect on the digestive stability of gluten.When the pH of the simulated gastric fluid was low,the activity of pepsin was higher,leading to easily degrade the wheat gluten with high molecular weight.With the increase of pH in simulated gastric fluid,the activity of pepsin was decreased,and there were more big fragments in the digestive products.Considering the enzyme activity of pepsin(optimum pH 1~2)and the stronger digestive capacity of adults than infants,the pH of gastric fluid is suggested to be 3.0 and 2.0 for infants and adults in the in vitro simulated digestion,respectively.4.The adding of BBM enzyme digestion is beneficial to the in vitro simulated digestion for the degradation of wheat gluten.The gluten content reduced to below 1200 ppm after simulated BBM enzymes digestion in infants,and the gluten content reduced to below 500 ppm after BBM enzymes were added in adults' digestive system.The results show that the BBM enzyme can significantly improve the degree of hydrolysis of wheat proteins,and the digested products have much weak immune reaction to the anti Glia-?9,indicating the celiac toxicity of gluten in the Xinjiang Nann is weakened.Accordingly,it is recommended that the BBM enzyme digestion should be involved for the in vitro simulated digestion of food proteins.