Modification And Application Of Wheat Bran Dietary Fiber And Its Probiotic Effect On Lactic Acid Bacteria

Wheat bran is rich in active ingredients,we can greatly improve the added value of wheat bran by further processing and utilization.In this paper,wheat bran insoluble dietary fiber(W-IDF)was extracted from wheat bran by enzymolysis and modified by carboxymethylation(C-IDF),complex enzymatic hydrolysis(E-IDF),and ultrafine comminution(U-IDF)respectively,the effect of different modification methods were studied;then the W-IDF or C-IDF was added into the dough to prepare bread,and the effect on flour farinograph properties,bread baking quality and starch digestibility in vitro were studied;meanwhile,the prebiotic effects of these two kinds of dietary fiber on lactic acid bacteria were studied.The purpose of this study is to provide theoretical basis for the application of wheat bran dietary fiber in the development of functional food.Comparison of wheat bran dietary fiber properties before and after modification.Structural characterization showed that these four kinds of dietary fiber had similar Fourier infrared spectrum characteristic absorption peaks;carboxymethylation and complex enzymatic hydrolysis significantly improved the thermal stability of W-IDF;and different modification methods had different effects on the microstructure.After carboxymethylation modification,all properties were improved except for nitrite ion adsorption capacity(NIAC);complex enzymatic hydrolysis greatly improved the oil retention(ORC),glucose adsorption capacity(GAC),and NIAC;the cation exchange capacity(CEC),GAC and NIAC of U-IDF reached the peak.Furthermore,all three modification methods significantly improved the antioxidant properties of W-IDF.Effect of addition of W-IDF or C-IDF on dough and bread properties.With the increase of the addition amount of W-IDF or C-IDF,the quality of the dough was improved.Further study after bread preparation indicated that with the increase of dietary fiber content,on the one hand,the specific volume,L* value,cohesiveness and springiness of bread decreased,while the a* value,b* value,hardness and chewiness increased,as a result,the baking quality of bread decreased;on the other hand,the in vitro digestion rate of starch in bread decreased,the content of rapidly digestible starch(RDS)decreased,the content of slowly digestible starch(SDS)and resistant starch(RS)increased,which lead to the improvement of nutritional characteristics of bread.In addition,the effect of C-IDF is more significant.Prebiotic effect of W-DF and C-IDF on lactic acid bacteria.W-IDF or C-IDF wasused to replace glucose as carbon source,and the probiotic effect on lactic acid bacteria was investigated by measuring the growth curve,p H change and total acid content change in the growth process of lactic acid bacteria;the ability of W-IDF and C-IDF to resist digestion of gastrointestinal fluid was studied by simulating artificial gastrointestinal fluid digestion experiment.At the same time,the known prebiotic inulin was used as the control.The results showed that both W-IDF and C-IDF could significantly promote the growth of lactic acid bacteria,and effectively resist the digestion of gastrointestinal fluid.They had typical prebiotic effect,and C-IDF was better than W-IDF.