The Study On Extraction,modification And Functional Characteristics Of Dietary Fiber From Potato Residuals

China is the largest potato production and consume country in the world.As a potato processing product,potato whole powder has been applied and developed rapidly in the food industry.However,a large number of residuals was produced during the processing of potato whole powder.Also,these residuals are rich in dietary fiber.In order to save resources,avoid environmental pollution and promote the deep development of potato resources,this study optimized the technology of potato dietary fiber extracted from these residual by enzyme-alkali method assisted by ultrasonic and the conditions of enzyme modification for the extracted potato dietary fiber.The structure,thermal properties,physical and chemical properties,and functional properties of the two dietary fibers before and after modification were compared and analyzed.The effects of two kinds of dietary fiber on intestinal fermentability and intestinal flora of mice were studied.The main research results were as follows:1.The extraction conditions of potato dietary fiber were optimized.Taking the extraction yield of dietary fiber as the index,ultrasonic-assisted enzyme-alkali was used to extract dietary fiber.Designed single-factor text,response surface test and verified.The results showed that the suitable extraction process conditions were as follows:ultrasonic power was 180 W,the ultrasonic temperature was 50℃,the addition amount of αamylase was 148 U/g,the digestion time was 35 min,the NaOH concentration was 3%,and the alkaline hydrolysis time was 14 min,under this condition,the yiled of dietary fiber reached 66.56%.2.The conditions of potato dietary fiber modified by complex-enzyme was optimized.With the content of soluble dietary fiber as the index,the potato dietary fiber was modified by cellulase-xylanase complex-enzyme.Designed single-factor text,response surface test and verified.The results showed that the suitable modification process conditions were as follows:the addition amount of complex enzyme was 0.18%,the enzymatic hydrolysis temperature was 51.00℃,the pH of enzymatic hydrolysis was 4.9 for 2 hours,under this condition,the content of soluble dietary fiber reached 26.82%.3.The structure,thermal properties,physical and chemical properties,and functional properties of the two dietary fibers before and after modification were studied.The analysis of structural characteristics results showed that the main monosaccharide components of the two kinds of potato dietary fiber before and after modification were glucose and galactose.Compared with potato dietary fiber,the contents of mannose,rhamnose,galacturonic acid,galactose,xylose and arabinose in the modified potato dietary fiber increased.After modification,the surface structure of dietary fiber was rough,cracks and porous structure was formed.In FTIR analysis,both potato dietary fiber and modified dietary fiber showed typical peak of polysaccharide absorption.The peak of XRD showed that they all had the characteristics of type I cellulose.After modification,the diffraction intensity of potato dietary fiber decreased,the crystallization area became smaller,and the soluble components were exposed.By analyzing the thermal properties of potato dietary fiber before and after modification,it was found that the modified potato dietary fiber showed better thermal stability in the range of test temperature from 30.0℃to 790℃.The analysis of physical and chemical properties results showed that the water holding capacity(WHC),oil holding capacity(OHC)and swelling capacity(SC)of sunflower seed oil of the modified dietary fiber were 9.03 g/g,6.67 ml/g and 2.95 g/g,respectively,which were 1.25 times,1.96 times and 1.9 times of the WHC,SC and OHC of sunflower seed oil,and the OHC of potato dietary fiber to sunflower seed oil was higher than that of soybean oil and peanut oil.The analysis of functional properties results showed that the adsorption capacity of glucose(GAC)was 137.2 mg/g,the removal capacity of nitrite(NRC)was 88.9%,the adsorption capacity of cholesterol(CAC)was 28.12 mg/g and 9.64 mg/g,when pH was 2 and 7,respectively,and the cation exchange capacity(CEC)was 0.56 mmol/g of the two dietary fibers.4.The effects of two kinds of dietary fiber before and after modification on short-chain fatty acids and intestinal flora of mice were studied.The content of short chain fatty acids in mice feces was used to explore the ferment ability of two kinds of dietary fiber in mice intestine.The results showed that dietary fiber promoted short chain fatty acids as a whole,and the effect of modified dietary fiber was more obvious.Among them,dietary fiber promoted acetic acid,butyric acid,isobutyric acid,pentanoic acid,common valeric acid,and inhibited propionic acid.The changes in the microbial community structure in mouse feces showed that the dietary fiber treatment group could significantly increase the number and diversity of the intestinal flora of the mice,and that the species diversity of the modified dietary fiber group was higher than that of the unmodified dietary fiber treatment group.Except for the high-dose dietary fiber group,the dietary fiber and modified dietary fiber groups increased with the increasing dose,the relative content of the Firmicutes decreased,and the relative content of Bacteroides was increased.The contents of microorganisms in and Ruminococcaceae increased,while the contents of Prevotellaceac decreased.