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The Effect Of Steam Explosion On The Physicochemical Properties,structure And Functional Properties Of Dietary Fiber From Adlay Bran

Posted on:2024-09-14Degree:MasterType:Thesis
Country:ChinaCandidate:X J TangFull Text:PDF
GTID:2531307109953059Subject:Food Science and Engineering
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Adlay bran is a by-product of the processing of adlay,which is rich in nutrients and has high biological activity,and is a good source of dietary fibre(DF).However,the low soluble dietary fibre(SDF)content of adlay bran limits its physiological functions and its application in the food sector.Steam explosion(SE)is a new modification technique that degrades large molecule carbohydrates into small molecule polysaccharides by acid hydrolysis,mechanical fracture and thermal degradation,which has the advantage of low energy consumption and high efficiency compared to other modification methods.At present,obesity has become a serious public health problem,with the number of obese people dramatically increasing in the world,and many studies have shown that DF can prevent and alleviate obesity.Therefore,in this paper,at first,SE was used to modify the dietary fibre from adlay bran,and the effects of SE on the content,physicochemical properties,in vitro hypoglycaemic activity and structure of SDF from adlay bran were investigated;secondly,the in vitro digestion and in vitro fermentation characteristics of SDF from adlay bran treated by SE were investigated.Finally,the effect of SDF from adlay bran treated by SE on fat reduction of high-fat diet-induced obese mice were evaluated in combination with animal experiments,with a view to providing a basis and reference for the comprehensive utilization of adlay bran.The main conclusions are as follows:(1)Effect of steam explosion on the content and physicochemical properties of SDF from adlay bran.SE treatment significantly increased(P<0.05)the SDF content of adlay bran,reaching a maximum of 9.37g/100 g at the steam explosion intensity of 0.8 MPa for 3 min,a significant increase of 27.48% compared to the SDF of adlay bran without SE treatment.And SE treatment significantly reduced(P<0.05)the content of cellulose,hemicellulose and lignin of adlay bran.In addition,SE treatment significantly increased(P<0.05)the oil holding capacity and cholesterol adsorption capacity of SDF from adlay bran,reaching a maximum at 0.8 MPa and 3 min,with a 0.47-fold and 3.03-fold increase,respectively,compared with the SDF from untreated adlay bran SDF.SE(except 1.2 MPa,1 min and 1.6MPa,1 min)significantly increased(P<0.05)the glucose adsorption capacity of SDF,reaching a maximum at 0.8 MPa,3 min,and a significant increase of 57.77% compared with the untreated control.SE significantly increased(P<0.05)the glucose dialysis retardation index and the α-amylase activity inhibition ability of SDF from adlay bran,and the glucose dialysis retardation index and α-amylase activity inhibition ability of SDF reached the maximum at steam explosion intensity of 0.8 MPa and 3 min.(2)Effect of steam explosion on structure SDF from adlay bran.The structure of SDF from adlay bran under optimal SE conditions(0.8 MPa,3 min)(SE-SDF)was characterized by laser particle size measurement,scanning electron microscopy(SEM),Fourier infrared spectroscopy(FT-IR)and differential scanning calorimetry(DSC).The results of particle size distribution showed that the SE treatment significantly reduced the average particle size of SDF and increased the specific surface area of SDF.The results of SEM showed that the surface of SE-SDF showed a honeycomb porous structure and the surface pore structure increased.The results of FT-IR showed that no new peaks appeared in the infrared spectrogram of SE-SDF and the positions of absorption peaks did not change significantly.The results of molecular weight showed that the heavy average molecular weight and number average molecular weight of SE-SDF were significantly lower(P<0.05)than those of SDF from adlay bran without SE treatment(0-SDF).The results of monosaccharide composition showed that the monosaccharide composition in SDF changed after SE treatment.The results of DSC showed that the peak temperature of SDF from adlay bran increased by 4.19℃ after SE treatment,and SE-SDF had better thermal stability.(3)Study on in vitro digestion and in vitro fermentation characteristics of SDF from adlay bran treated by steam explosion.Total phenolic content and flavonoid content and antioxidant capacity of SDF from adlay increased after SE treatment,and the contents of Coumaric acid,Protocatechic acid,P-Coumaric acid,Rutin,P-Hydroxybenzoic acid,and Myricetin in SE-SDF increased significantly(P<0.05)compared with 0-SDF.The total phenolic and flavonoid contents and antioxidant capacity of SDF digest appeared to increase to different degrees during in vitro digestion,and the total phenolic and most phenolic compounds contents and antioxidant capacity of SE-SDF digest were higher than 0-SDF digest.The in vitro fermentation results showed that SE-SDF reduced the p H of the fermentate and increased the content of acetic acid,propionic acid,butyric acid and total SCFAs in the fermentate compared with 0-SDF.In addition,at the phylum level,SE-SDF significantly reduced the abundance of Proteobacteria and increased the abundance of Bacteroidota and Actinobacteriota in the fermentate compared with 0-SDF.At the level of genus,SE-SDF can promote the proliferation of beneficial bacteria such as Lactobacillus,Bifidobacterium and Blautia and inhibit the proliferation of harmful bacteria such as Escherichia-shigella.SE-SDF can improve the intestinal microbial composition,promote the growth and reproduction of beneficial bacteria and inhibit the growth and reproduction of harmful bacteria.(4)To investigate the weight losing effect of SE-SDF on obese mice using high-fat diet-induced obese mice as a model.The results showed that both high and low concentrations of SE-SDF could effectively reduce the weight gain of mice induced by high-fat diet and slow down the fat accumulation caused by high-fat diet,especially high concentration of SE-SDF was more effective.High concentration of SE-SDF significantly reduced(P<0.05)the serum levels of TC,TG,LDL-C,leptin and pro-inflammatory cytokines(TNF-α,IL-6)and increased the levels of HDL-C and anti-inflammatory cytokines IL-10,thus improving the serum inflammation level in obese mice.In addition,SE-SDF could effectively improve the intestinal microbial community composition of obese mice.After gavage of high and low concentrations of SE-SDF respectively,the abundance of Bacteroidota in the feces of obese mice increased,the abundance of Firmicultes decreased,and the F/B ratio decreased;SE-SDF could control body weight and prevent obesity by reducing the F/B ratio.Moreover,compared with the high-fat model group,the abundance of Ackermania and Bifidobacterium increased in the mice of high concentration of SE-SDF.SE-SDF changed the structure and composition of intestinal flora in high-fat diet-induced obese mice,and could promote the growth and reproduction of beneficial bacteria.
Keywords/Search Tags:adlay bran, dietary fiber, steam explosion, intestinal flora, obesity
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