Evaluation Of Storage Characteristics,Nutritional Quality And Intestinal Probiotics Of Konjac Wet Rice

The rapid progress of science and technology and social economy has promoted people to seek a healthier lifestyle to change the diet habit of high carbohydrate,high calorie and high fat.The dietary requirement of low fat,low sugar and low calories can cope with the daily life of special people such as patients with diabetes,hypertension,hyperlipidemia and hyperglycemia,and weight managers.Konjac glucomannan（KGM）is rich in dietary fiber,contains more than ten kinds of amino acids and many kinds of trace elements required by human body,and has the characteristics of low fat,low calorie and high nutritional value.The rice granular konjac wet rice prepared by the double screw extrusion mechanism is a kind of konjac gel bionic food,which can transform konjac,a non food crop,into a functional staple food and provide new options for special people.The subject takes konjac wet rice as the research object,and studies the storage characteristics,nutritional quality and intestinal probiotics of konjac wet rice.Through the quality change of konjac wet rice with alkaline electrolytic water（AIEW）of different pH values as storage solution,the effect of AIEW on the storage quality of konjac wet rice was investigated.Study on the formula rice with different amounts of konjac wet rice,carry out the optimization of the eating method of formula rice,and evaluate its nutritional digestion characteristics,in vitro simulated adsorption characteristics and intestinal probiotics.To provide optimal reference and certain data support for mass staple food consumption.The main research methods and conclusions are as follows:（1）AIEW（pH9.51-12.52）,distilled water（pH6.95）and citric acid（pH3.12）were stored as storage solution of konjac wet rice.The water holding capacity,color,total bacterial count,pH and turbidity of storage solution of konjac wet rice were monitored at 4℃,25℃and 37℃.Results showed that the AIEW can delay konjac wet rice with water drop,hold water at low temperatures keep ability is stronger.At 4℃,the water retention of Konjac wet rice stored by AIEW remained above 90%for 45 days,and AIEW with pH10.53 for 60 days.TheΔE of Konjac wet rice increased gradually with the increase of storage time,and the high pH AIEW has a stronger ability to inhibit the browning of Konjac wet rice,and the effect is better at low temperature.The high temperature sterilized storage solution can effectively inhibit the microbial propagation of Konjac wet rice.The sterilization effect of AIEW was stronger than that of citric acid and distilled water at different ambient temperatures,and increased with the increase of pH value of AIEW.Stored for 180d,the total number of colonies was less than 100cfu/g,which met the requirements of commercial sterilization.With the increase of storage time,the pH of AIEW storage solution decreased gradually and tended to equilibrium at pH8.5.The equilibrium stability time was prolonged with the increase of pH of AIEW,and the effect was better at low temperature.AIEW as storage liquid can reduce the degree of turbidity,maintain the gel quality of Konjac wet rice better,and extend the shelf life.（2）Selected the konjac wet rice with different addition levels（DSM2=25%,DSM3=50%,DSM4=75%）and rice for cooking,while pure refined rice（DSM1）and pure konjac wet rice（DSM5）were as the control groups.The edible quality was evaluated by color,sensory evaluation,texture characteristics,and cooking characteristics,and the changes in nutritional composition,aroma characteristics and in vitro starch digestibility were compared.Results showed that compared with DSM1,the color and sensory evaluation of DSM2 and DSM3 had no significant difference,but the cooking water absorption increased.The viscosity and the hardness of the three kinds of formula rice decreased,but the DSM4 rice was soft and rotten and excessively gelatinized,which reduced the edible taste and cooking quality of the formula rice.With the increase in the amount of konjac wet rice,the dietary fiber content and aroma flavor of the formula rice increased,and the digestibility and hydrolysis rate of starch in vitro decreased.The addition of konjac wet rice can supplement dietary fiber,slow down the hydrolysis of rice starch,and improve the edible taste of formula rice.This study can provide support for the application of konjac wet rice in staple foods.（3）The adsorption properties of Konjac wet rice formula on heavy metal ions and bile acids in simulated gastrointestinal environment and the intestinal probiotic effect of external fermentation of human cecum contents were further evaluated.Results showed that the adsorption capacity of heavy metal ions Pb²⁺,Cd²⁺and Cu²⁺increased with the increase of Konjac wet rice content,and the adsorption capacity of bile acid increased gradually.The adsorption rate of DSM4 could reach 66.23%of DSM5,and the adsorption capacity of simulated intestinal environment was higher than that of simulated stomach environment.The adsorption capacity of Pb²⁺,Cd²⁺and Cu²⁺decreased to a certain extent in the presence of trace elements.DSM1,DSM3,DSM4and DSM5 were selected for in vitro anaerobic fermentation.Results showed that with the increase of Konjac wet rice content,the ability of generating short-chain fatty acids（SCFAs）and the content of SCFAs increased gradually.The pH of fermentation broth of formula rice decreased gradually,and the decreasing trend was slowed down with the increase of Konjac wet rice content.16S r DNA gene sequencing analysis showed that 744 effective OTUs were obtained from four groups of formula rice,and the number of OTUs owned by each group alone increased with the increase of konjac wet rice.Alpha diversity and Beta diversity analysis showed that the addition of konjac wet rice could adjust the microbial flora structure of the formula rice.OTU cluster analysis showed that the microflora structure of the rice-containing group was in the same branch,while the konjac wet rice group was in another branch,indicating that the species abundance and evenness of the rice group were significantly different from that of konjac wet rice.The analysis of intestinal microflora structure showed that the addition of konjac wet rice increased the abundance of the beneficial bacteria of the formula rice,such as Megasphaera,Bifidobacterium,Weissella and Prevotella-9,and decreased the abundance of Proteobacteria.DSM3 has the highest abundance of Weissella and Prevotella-9,DSM4 has the highest abundance of Bifidobacterium.The proportion of Bacteroidetes/Firmicutes in pure konjac wet rice DSM5 was significantly higher than that in the rice-containing group.The consumption of Konjac wet rice formula and pure Konjac wet rice promoted the species richness and evenness of different intestinal flora to exert their intestinal probiotic activities.