Study On The Modification And Performance Of Leishan Dietary Fiber

Phyllostachys praecox f.Prevernalis is a high-quality edible bamboo shoot,which contains protein,amino acids,vitamins,minerals,cellulose,and other ingredients.The cellulose content is only 3%,but the insoluble dietary fiber(IDF)is the main,while the soluble dietary fiber(SDF)is only about 1%,so that its functional value has not been fully developed.To enhance the SDF ratio in bamboo shoots,the bamboo shoots were treated with three modifications(subcritical water(SW),high pressure homogenization(HPH),and enzymatic method(EM).The changes of physicochemical properties and the structural characteristics of dietary fiber(DF)were also studied.Finally,the effects of bamboo shoots dietary fiber on short-chain fatty acids in in vitro fermentation were discussed.The conclusions are as follows:(1)Three modifications(SW,HPH,and enzymatic method)were used to modify the dietary fiber of the bamboo shoots,and their conditions were optimized,respectively.The SW modification optimization process conditions were :the ratio of material to liquid 1:50,the temperature 135°C,the treatment time 30 min,and the SDF yield was10.70% ± 0.42%;The HPH modification optimization process conditions were:the ratio of material to liquid 1:50,the pressure 130 MPa,the treatment time 30 min,and the SDF yield was 7.41% ± 0.20%;The EM modification optimization process conditions were:addition of 0.15% cellulase,pH=6.8,50°C,2 h,then added with 0.15% xylanase,pH=4.8,3 h,the SDF yield was 6.80% ± 0.15%.Compared with untreated SDF(1.02%± 0.04%),all the three modifications can significantly increase the SDF content.(2)SW,HPH,and EM modification can increase the hydration properties(water holding capacity and swelling power),nitrite adsorption capacity and cholesterol adsorption capacity of dietary fiber(P < 0.05).The total phenol content in DF increased significantly after enzyme modification and HPH modification,and the antioxidant capacity was improved(P < 0.05).However,the total phenol content and oxidation resistance of DF after SW modification were significantly reduced.(3)The structural changes of dietary fiber before and after modification were analyzed by scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FT-IR)and X-ray diffraction(XRD).It was found that the surface of DF that modified with SW was porous;the size of DF that modified with HPH particles was reduced;the pore size increased and the specific surface area increased after enzymatic modification;FT-IR results indicated that lignin and cellulose had different degrees of degradation after being treated by three modification methods;XRD showed that the DF crystallinity decreased after treatment by the three modified methods.(4)Before and after the modification,the content of acetic acid,propionic acid and butyric acid could be increased after in vitro fermentation.Although the total acid content was increased after the fermentation,the proportion of fermentation products in the intestinal flora was not significantly changed,and with no effects on gas production during fermentation.