Dietary Fiber Derived From Wheat Bran Following Bacillus Amyloliquefaciens Modification And Its Application In Pasta Products

Wheat products occupy an important role in our diets,but the refinement and industrialization of grain processing has led to a large number of wheat by-products being discarded,resulting in the loss of nutrients in pasta products,and there are also deficiencies in the processing performance of dough that make it difficult to meet the needs of industrial scale.Therefore,it is of great practical importance to research and develop a high value-added pasta product using wheat bran as raw material.In this experiment,glucomannanase from Bacillus amyloliquefaciens was first used to increase the yield of soluble dietary fiber(SDF)from wheat bran and to improve the structural and functional properties of the dissolved fiber.The results showed that enzymatic modification increased the yield of SDF by 34.2%.Gel permeation chromatography(GPC),scanning electron microscopy(SEM)and thermogravimetric analysis(TGA)revealed that the molecular weight of SDF was reduced and the branches were more numerous and finer after enzymatic digestion.Nuclear magnetic resonance analysis(~1H NMR)and Fourier transform infrared spectroscopy(FT-IR)showed partial degradation of hemicellulose.Also,the physicochemical results showed that the SDF obtained from the enzyme treatment exhibited better water holding power,water solubility,swelling power and antioxidant activity(p<0.05).The soluble dietary fibers before(K-SDF)and after(Y-SDF)modification were applied to wheat flour,fresh dough and frozen dough in a graded addition of 0%,2%,4%and 6%.The effects of SDFs on the pasting and regeneration properties of the flour system and on the rheological properties,thermodynamic properties,gluten structure,water migration,color variation and frozen storage of the dough were investigated.The results of the study are as follows:In the SDF-flour system,rapid viscosity analysis(RVA)and rheological properties indicated lower energy storage modulus(G’),loss modulus(G’’)and thixotropy in the blended system,which may account for ability of SDF to inhibit starch swelling,as further evidenced by the significant reduction in peak viscosity,peak-valley viscosity and final viscosity during starch pasting,with the addition of SDF inhibiting the formation of a continuous gel network structure,in which the influence of Y-SDF was stronger.In the SDF-fresh dough system,rheological measurements and FT-IR showed an increase in the elastic viscosity of the mixed dough,a shift of gluten proteins towardsαandβ-structures,a more compact and ordered network structure and a stronger negative effect of K-SDF on the resistance of the dough to deformation.Low-field nuclear magnetic analysis(LF-NMR)and TGA analysis showed that the addition of SDF redistributed the moisture in the dough and its water retention and thermal stability were enhanced.In addition,the introduction of Y-SDF led to a significant color difference in the dough,a decrease in L*and an increase in a*and b*.In the SDF-frozen dough system,theα-helix content of frozen dough decreased andβ-folding increased.The introduction of SDFs stabilized the changes in the secondary structure of gluten protein and reduced the magnitude of changes in G’,G’’and|G*|,while inhibiting significantly the flow of water and the generation of ice crystals in the dough during freezing,especially Y-SDF was more effective in enhancing the freezing stability of dough and alleviating freezing deterioration.In summary,this study provides a scientific basis for the comprehensive utilization of wheat bran in the food industry and the industrialization of pasta products.