Effect Of Cooking And Storage Methods On Resistant Starch Content And Probiotic Function Of Noodles

Resistant starch is a hotspot in the field of starch science.The content of resistant starch?RS?in food is not only affected by raw materials,but also related to factors such as cooking methods and storage conditions.In order to study the effects of typical cooking and storage methods on the RS content and digestion characteristics of traditional Chinese staple foods,this experiment used common staple white salt noodles as the research object,and cooked them by cooking,steaming,microwave heating,stir-frying and frying.Stored the cooked noodles at-18?,4?and 25?for 4h,24h and 48h respectively,and analyze the effect of different cooking methods and storage conditions on the RS content in the noodles;The first-order kinetic equation was used to analyze the digestion curve of starch in noodles and calculate the value of estimated glycemic index value?eGI?;The crystal structure,thermal characteristics and microstructure of starch in noodles were analyzed by X-ray diffractometer?XRD?,differential scanning calorimeter?DSC?,and scanning electron microscope?SEM?;The change rule of noodle digestion characteristics and its correlation with starch structure?crystal structure and microstructure?are clarified.In addition,wheat RS₃ was added to the feed and the high-throughput sequencing technology was used to study the regulation of wheat type?resistant starch on the intestinal flora and metabolites of type?diabetic rats.The probiotic function of wheat RS₃ was initially explored.The main research conclusions are as follows:?1?Different cooking and storage methods can significantly change the noodle RS content.The RS content in the noodles after microwave heating was highest?0.99%?;the second one was in the stir-fried noodles?0.59%?;the RS content is lower and similar in the noodles after boiling and steaming?0.43-0.44%?;The content in the fried noodles is the lowest and almost all disappear.After 24 hours of storage,the RS content in the noodles increased significantly.The noodles stored at 25°C had the highest RS content and the lowest digestibility and digestion rate.The RS content in noodles had a significant negative correlation with digestion rate,and a positive correlation with starch crystallinity.?2?The digestion rate of noodles after microwave heating and stir-frying is slow(0.202 min^-1 and0.0290 min^-1),and the digestion rate after boiling,steaming and frying is faster(0.0411 min^-1,0.0354min^-1 and 0.0423 min^-1).The freshly noodles obtained by different cooking methods belong to high GI foods?86.18-98.33?,however,in which the eGI index of noodles after microwave and deep frying is relatively low;after storage,the eGI index of noodles drops significantly,and some noodles change from high GI index foods?>70?to the medium GI index foods?55<GI?70?,such as microwave heated noodles stored for 4h and 24h at room temperature,the eGI values drop to 66.96 and 66.75.?3?Wheat RS₃ has no significant effect on the body weight,blood glucose and organ index of rats.The effect of diet on intestinal flora is earlier than the effect on apparent state and physical signs.?4?The RS₃ diet significantly reduced the abundance of fecal bacteria in rats,promotes the growth of some probiotics,and inhibits the growth of some harmful bacteria.Significantly increased the relative abundance of beneficial bacteria such as Akkermania and Intestinimonas and played a certain role in inhibiting pathogenic bacteria such as Lachnospiraceae and Trichococcus.At the same time,the ratio of relative abundance of the Firmicutes and the Bacteroidetes?F/B value?in the intestinal flora of rats which is related to the obesity are decreased with RS₃ feed.