Study On Modification And Functional Properties Of Rice Bran Dietary Fiber By Steam Blasting-Ultramicro-Crushing Technology

As a by-product of grain processing,rice bran is a pure natural product that is non-toxic and harmless and can be used to improve people’s diet.People’s living standards are constantly improving,their diets are becoming more and more refined,and the lack of dietary fiber in their diet is becoming more and more serious.The research and application of dietary fiber will become one of the research hotspots of functional food.On the basis of rice bran abroad,various rice bran health foods and snack foods have been successfully developed and achieved good economic benefits.Therefore,drawing on foreign experience,increasing the in-depth development and comprehensive utilization of Chinese rice bran,and developing rice bran nutritional function food is one of the research directions of food workers.In this experiment,defatted rice bran was used as raw material to extract RBDF by complex enzymatic hydrolysis method.The extracted RBDF was first modified by the optimal steam blasting scheme,and then subjected to ultrafine treatment by jet pulverization and nano-impact grinding.The effects of composite modification on the structure,physicochemical properties and physiological functions of RBDF were studied by using RBDF without complex modification(C-RBDF).Effects of compound modification on growth characteristics,blood lipid levels and tissue pathology of RBDF in mice with type 2 diabetes mellitus;steam explosion-superfine pulverization of RBDF in four aspects of surface preparation,study on the structure of modified RBDF And the impact of functional properties.The main research contents and results are as follows:(1)In order to determine the optimal scheme for steam blasting,a single factor experiment was first carried out.Taking the yield of SDF as the label,the factors and variables were determined as:steam pressure(0.3～0.9MPa)and pressure time(240-360s).Then using the response surface design experiment and adopting the general rotation combination design principle,the optimal process conditions for steam explosion treatment SDF are as follows:steam pressure 0.631MPa,dimension pressure time 302.866s,SDF yield under this condition is 6.987%.The RBDF treated by the optimal process conditions of steam explosion is further subjected to ultra-micronization treatment.,and dried by a jet mill and a high-energy nanoball mill to obtain S-M-RBDF and S-N-RBDF.The SDF extraction rates of the two samples were compared with those of C-RBDF.Increased by 2.28 and 2.77 times.(2)The particle size of steam-blasted S-RBDF is larger than that of C-RBDF,it may be because during the steam explosion treatment of S-RBDF,the particles expand instantly when the pressure is released,and the internal looseness enlarges,resulting in the RBDF particle size becoming larger.And both ultra-micronization treatments can significantly reduce the particle size of RBDF and increase the specific surface area.The particle sizes of S-M-RBDF and S-N-RBDF were reduced by 80.2%and 89%,respectively,and the specific surface area was increased by 12.25 times and 20.65 times.In the infrared spectrum,there was no new absorption peak in the RBDF infrared spectrum before and after steam blasting-ultrafine pulverization treatment.The peak shape,position and number of peaks of the characteristic absorption peaks did not change significantly,indicating that after physical modification,RBDF No significant change in chemical composition.The structure of S-RBDF fiber in SEM is broken,broken,the surface is uneven,the structure is loose,the RBDF particles treated by ultrafine pulverization are obviously reduced,the honeycomb structure on the surface becomes denser,the specific surface area is increased and exposed in the molecule.More groups to improve its hydration properties.After testing,the swelling,oil and oil holding capacity of RBDF treated by composite modification were significantly improved(p<0.05);the adsorption capacity of modified RBDF glucose was enhanced,and the adsorption of S-N-RBDF was the strongest;When the particle size is less than 20 μm,the cation exchange capacity is gradually decreased,so the cation exchange power of S-M-RBDF is the strongest.(3)In the effect of RBDF on blood glucose in type 2 diabetic mice,the weight of diabetic mice gradually increased under the action of RBDF.The mice in SM and SN group were significantly higher than those in DM group,indicating that RBDF had significant intervention effect on the symptoms of weight loss in type 2 diabetes,and the intervention in SN group was the most obvious.In the SM and SN groups,the blood glucose level at the end of the experiment was 18.3%,4.9%,and 6.4%lower than that of the previous group.The male rats were 18.4%,4.2%,and 13.2%lower than before,indicating that RBDF has hypoglycemia.Role,where S-N-RBDF effect is more obvious.The results of biochemical indicators in mice showed that RBDF can decrease serum total cholesterol(TC),total triglyceride(TG)and low density lipoprotein(LDL-C)levels(p<0.05)and increase high density lipoprotein(HDL-C);simultaneously enhance the activity of superoxide dismutase(SOD)in the liver and reduce the content of malondialdehyde(MDA),wherein the effect of S-N-RBDF is more significant.The above results indicate that RBDF has a protective effect on diabetic mice.(4)S-N-RNDF was added to the hair cake at an addition amount of 2%,5%,and 7%,and a hair cake to which no RBDF was added was used as a control group.The results showed that with the increase of dietary fiber,the peak viscosity,final viscosity and retrogradation parameters of the mixed powder gradually decreased,but the reduction was smaller.At the same time,the hardness and chewiness of the cake increased,and the elasticity decreased.In the low field NMR,the T2 relaxation time of the two peaks in the hair cake with 2%RBDF added to the fast relaxation direction,and the difference was significant(p<0.05).However,the moisture mobility of the cake with 5%-7%RBDF was poor compared with the blank group,and the relaxation time was shortened.In the sensory evaluation,the addition of an appropriate amount of RBDF had no significant effect on the sensory evaluation of the product,and 2%RBDF was the optimum addition amount.