Study On Enzymatic Extraction Technology And Application Of Insoluble Dietary Fiber From Oat Bran

Oat bran was the main by-product of oat processing.The dietary fiber(DF)in oat was mainly concentrated in bran.However,oat bran was mainly used for livestock feed,with low utilization rate and low added value.In this paper,oat bran was used as raw material to extract insoluble dietary fiber(IDF)from oat bran by enzymolysis.The parameters of extraction process were optimized by response surface,and IDF was further purified and characterized by the combined action of alkali/heat/alcohol.The effects of IDF with different particle sizes on its physical and chemical properties were studied.The main results are as follows:The optimal process conditions for extracting oat bran IDF by using a combination of?-amylase and neutral protease were obtained through single-factor experiments and response surface methodology:the ratio of material to water was 1:12.1,the concentration of?-amylase was 1.85%,enzymatic hydrolysis time was39.14 min.Under these conditions,the extraction rate of IDF is 20.1%and the purity is 33%.The enzymatic hydrolysis kinetics of?-amylase hydrolyzed oat bran starch was investigated.The parameters were solved by Wilkinson statistical method.The maximum reaction rate was V_m=2.932 mg/(m L·min),and the Mie constant was K_m=11.349 mg/m L,the kinetic equation was:v=2.932[S]/11.349+[S].The crude fiber was further purified with 4%sodium hydroxide,70?hot water and 95%ethanol,and the purity of IDF was increased from 33%to more than 95%.X-ray diffraction(XRD)analysis showed that the enzyme treatment had no significant effect on the lattice structure of IDF during the enzymatic hydrolysis,and the purification treatment did not change the crystal form of IDF.Differential scanning calorimetry(DSC)analysis showed that IDF has high thermal stability below 250?.Light microscopy and scanning electron microscopy(SEM)showed that the surface of the purified IDF has a loose and porous honeycomb-like structure,and the apparent structure has a spatial network.Fourier transform infrared spectroscopy(FTIR)test showed that both crude fiber and purified IDF have characteristic absorption peaks of polysaccharides.There are significant differences in the functional properties of IDFs with different particle sizes.As the particle size decreases,the water holding capacity,oil holding capacity,expansion force,nitrite ion adsorption capacity,and cation exchange capacity of IDF all increase first and then decrease trend.IDF adsorption of NO₂^-ions occurs mainly in gastric fluid.With the decrease of particle size,the dissolution rate of total phenol and total flavonoids in IDF gradually increased.Comprehensive analysis of the effect of particle size on the functional characteristics of IDF,Oat bran IDF with particle size of 80 has the potential to be added as a functional component to food and health products.In this paper,oat bran IDF was used as raw material to prepare chewable tablets for children,the general public and the elderly.The content of IDF in children's and the general public's chewable tablets was more than 30%,and the content of IDF in the middle-aged and the elderly's chewable tablets was more than 35%.