| Black rice is rich in dietary fiber,but the majority of it is insoluble dietary fiber,which limits the utilization of black rice.In order to improve its comprehensive utilization rate and promote the development of black rice related products,Neurospora crass was used to modify black rice by fermentation,and the modification process was explored in order to increase the content of soluble dietary fiber in black rice.The structural and functional properties in vitro of unfermented modified black rice dietary fiber and fermented modified black rice dietary fiber were compared.The cholesterol-lowering effect of fermented modified black rice dietary fiber and its effect on intestinal flora were evaluated by animal experiments,and the fermented modified black rice dietary fiber chewable tablets were developed.Findings were as follows:(1)Study on fermentation modification of black rice.In order to improve the dietary fiber content,especially the proportion of soluble dietary fiber,the fermentation modification process was optimized by using the cellulase activity as the index.The optimal fermentation time was 6 d,temperature was 29 ℃,and solid-liquid ratio was1:0.6 g/m L.Under the modified fermentation conditions,the cellulase activity of Neurospora crassa was 2.399 U.(2)Study on Functional characteristics of fermented modified black rice dietary fiber.The composition,in vitro functional properties and structure of fermented modified black rice dietary fiber and unfermented modified black rice dietary fiber were determined.The soluble dietary fiber content of black rice increased from 17.31% to 29.69%,the insoluble dietary fiber content decreased from 62.13% to 51.96%,and the total dietary fiber content increased from 79.4% to 81.7%.The content of dietary fiber was significantly different.The water holding capacity of fermented modified black rice dietary fiber increased from2.91 m L/g to 6.80 m L/g.The oil holding capacity increased from 1.30 g/g to 3.42 g/g,and the water absorption expansion capacity increased from 2.33 g/g to 4.33 g/g.It was possible to raise the adsorption capacities of sodium cholate from 0.56 mg/g to 0.58 mg/g,glucose from 8.66 mg/g to 8.72 mg/g,and cholesterol from 0.56 mg/g to 49.21 mg/g(p H=2)and 59.22 mg/g(p H=7).The results of SEM showed that the fermentationmodified black rice dietary fiber had loose and porous structure,and the X-ray diffraction showed that the fermentation-modified black rice dietary fiber did not change its crystal structure.(3)Cholesterol-lowering properties of fermented modified black rice dietary fiber.Male C57BL/6J mice were used to establish a hypercholesterolemia mouse model.The mice were given high dose(FBH)and low dose(FBL)fermented black rice dietary fiber by gavage.After 5 weeks of feeding,the average body weight of FBH mice was 28.19 g,and the average body weight of FBL mice was 30.54 g.Compared with the model group(FG)mice,they were decreased by 14.12% and 6.0%,respectively.The fat weights of heart,liver,spleen,kidney and epididymis were significantly reduced with fermented modified black rice dietary fiber intervening.In FBH mice,TBA was decreased to 8.093μmol/g,CYP7A1 was increased to 2.097 ng/m L(p<0.01),HMGCR was decreased to526.027 pg/m L,LCAT was decreased to 4.53 ng/m L,Apo-A1 was increased to 2.566μg/m L.Apo-B was reduced to 349.166 μg/m L,and the related indicators of cholesterol metabolism in mice returned to normal.Compared with FG mice,the contents of propionic acid and valeric acid returned to normal,the contents of acetic acid,butyric acid and isobutyric acid were improved,and the intestinal flora was effectively regulated in FBH intervention mice,which increased the level of Akkermansia and decreased the level of Firmicutes.(4)Study on the formula of fermented modified chewable tablets of black rice dietary fiber.Fermented modified black rice dietary fiber chewable tablets were made of fermented modified black rice dietary fiber,maltodextrin,magnesium stearate and stevioside as auxiliary materials,which were prepared by direct tablet pressing method.Based on the overall score of chewable tablets,the formula for the fermented modified black rice dietary fiber chewable tablets was improved.Finally,the additive amount of maltodextrin was 30%,magnesium stearate was 3%,stevioside was 0.09%,and the hardness of the black rice dietary fiber chewable tablets was 59.8N,the crispness was35.45 N,the difference in slice weight was 1.43%,the sensory score was 91,and the comprehensive score was 25.61.On this condition,the quality of the chewable tablets are good,moderate hardness,taste fresh. |
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