| In this paper,the water insoluble arabinoxylan(WUAX)extracted from corn bran by ultrasonic-microwave assisted alkali method was used as raw material.Cellulase was applied for the preparation of small-molecule arabinoxylan(SMAX).Single factor and respone surface methodology were carried out to optimize the preparation process of SMAX.The differences of structural properties,physicochemical properties and functional characteristics between SMAX and AX were studied by high performance liquid chromatography(HPLC)analysis,Fourier transform infrared(FT-IR)spectroscopy analysis,Ultraviolet-visible(UV-vis)spectroscopy analysis,particle size and rheological characteristics analysis.Experimental research conclusions were as follows:(1)The results showed that the content of polysaccharide in AX was 79.20 %,the content of protein,fat,ash and water was 0.25 %,2.67 %,8.21 % and 9.35 %,respectively.Taking the degree of hydrolysis as the response,the optimal conditions were as follows: the amount of enzyme of 5000 U/g,the time of enzymatic hydrolysis of 2.5 h,the temperature of enzymatic hydrolysis of 42 ? and pH 5.Under such conditions,the degree of hydrolysis of AX was 51.24 %.(2)The analysis of monosaccharide composition indicated that the content of xylose and arabinose was higher in SMAX and AX.The glucose content in AX(22.3 %)was higher than that in SMAX(6.1 %).The results of molecular weight showed that the molecular weight of AX was 305 KDa and that of SMAX was 8.9 KDa.The results of FT-IR spectra showed that the main functional groups of SMAX did not change significantly,and arabinose and ?-D xylose existed in the SMAX.(3)The results of solubility test showed that SMAX and AX could dissolve completely.Under the same conditions,the SMAX was not easy to be affected by the dissolution temperature,pH and NaCl,and the dissolution rate was faster.The results of stability test showed that AX was more tolerant to high temperature,and SMAX was more tolerant to pH.The results of UV-vis spectra showed that SMAX and AX did not have nucleic acid,but contained a small amount of protein.The content of protein in SMAX was lower than that of AX.The results of particle size measurement showed that the median diameter and area average diameter of SMAX increased significantly,which might be due to the change of branched chain of AX during the enzymatic hydrolysis process,making the size of SMAX larger and uneven.The results of static and dynamic rheological analysis showed that the apparent viscosity of SMAX decreased,and both SMAX and AX exhibited shear thinning phenomenon.The storage modulus(G')and loss modulus(G'')were positively correlated with the angular frequency.The G' values of SMAX and AX were similar,but the G'' value of SMAX was decreased.Both SMAX and AX showed weak gel properties.(4)The results of functional characteristics showed that the foaming property and foaming stability of SMAX were significantly higher than that of AX in the test concentration range of SMAX and AX,while the emulsifying property and emulsifying stability were decreased.Research results of probiotics in vitro showed that SMAX and AX promoted the growth of Lactobacillus fermentans,Lactobacillus bulgaricus and Streptococcus thermophilus,and the growth of Streptococcus thermophilus was the best.In the same culture time,the biomass of lactic acid bacteria with SMAX as carbon source were higher and the pH values were lower,which indicated that SMAX was more easily utilized by these three kinds of lactic acid bacteria and produced acid metabolite.The three kinds of lactic acid bacteria grown with SMAX and AX as carbon sources showed similar tolerance to gastrointestinal environment.These lactic acid bacteria had higher tolerance to ?-amylase and pancreatin,and a certain degree of tolerance to pig bile salt,but poor tolerance to acid environment. |
PDF Full Text Request