Preparation Of High Dietary Fiber Coffee And Its Intervention Effect On Alzheimer’s Disease Model Mice

With the advent of the era of food health,the research of functional foods and related nutritional intervention is becoming one of the important directions in food science field.As a favorite functional drink,coffee has physiological functions such as losing weight,inhibiting cancer,reducing the risk of cardiovascular disease and neurodegenerative disease.However,it is found that extracted coffee is easy to produce precipitation during long-term storage in industrial production,which affects the sensory quality.The purpose of this study is to develop a concentrated dietary fiber coffee(HDC)as a dietary fiber supplement to solve the precipitation problem of extracted coffee.The neurodegenerative disease model was used to explore the neuroprotective effect of HDC on Alzheimer’s disease(AD)model,so as to provide a theoretical basis for the development of HDC as a healthy food.The main results are as follows:(1)Firstly,six kinds of coffee beans with different origins were collected,and the contents of fat and main active components were determined by Soxhlet extraction method,spectrophotometry and liquid chromatography.Then coffee was extracted by drip method,decocting method,ultrasonic assisted extraction method,microwave-assisted extraction method and pressure extraction method.The basic physico-chemical properties and aroma components of coffee with different extraction methods were explored.The results showed that Guatemalan coffee beans had the highest fat content(15.20 ± 0.43%).Robusta coffee beans had the highest total phenol content(61.45 ± 1.65 mg GAE/g),followed by Kenyan coffee beans(58.27 ± 0.85 mg GAE/g).The contents of trigonelline(6.11 ± 0.01 mg/g DW)and chlorogenic acid(9.94 ± 0.01 mg/g DW)in Kenyan coffee beans were the highest.The caffeine content of Robusta coffee beans was significantly higher than that of other coffee beans(P < 0.05).There was little difference in p H and color of coffee extracted by five extraction methods.The titratable acid value of coffee extracted by drip method was the highest,and the total solid content of coffee extracted by ultrasonic assisted extraction method was the highest.The total phenol(5.36 ± 0.13 g GAE/L),trigonelline(891.32 ± 13.26 mg/L),chlorogenic acid(1063.33 ± 3.00mg/L),caffeine concentration(1562.26 ± 14.28 mg/L)and antioxidant activity of coffee prepared by pressure extraction were significantly higher than other methods(P < 0.05).The coffee extracted by pressure extraction had the highest sensory score and the most abundant aroma components.Based on the above results,Kenyan coffee beans and pressure extraction method were selected for follow-up experiments.The HDC prepared under this condition has high antioxidant activity,good sensory,and the content of dietary fiber meets the national standard for high dietary fiber drinks.(2)Secondly,the effects of different solid-liquid ratio,polydextrose addition and white konjac flour addition on the basic physical and chemical properties and sensory of HDC were studied.The analytic hierarchy process(AHP)was used for comprehensive scoring to determine the preparation conditions of HDC.The results showed that with the increase of white konjak flour addition,the viscosity,total solids and concentration of main active components of HDC increased,and the centrifugal precipitation rate decreased significantly(P < 0.05).With the addition of polydextrose increasing,the viscosity of HDC decreased,the concentration of total solids,main active components and the centrifugal precipitation rate were increased.The viscosity of HDC increased firstly and then decreased,the concentration of total solids,main active components and the centrifugal precipitation rate was decreased when the ratio of material liquid decreased.Spearman correlation analysis showed that the centrifugal precipitation rate was related to total solids and viscosity of HDC.The final preparation conditions were as follows: the addition amount of white konjak flour was 0.6%,the addition amount of polydextrose was 3% and the material liquid ratio was 1:3.(3)Finally,the effects of HDC on cognition and memory of AD model mice were observed by Morris water maze.16 S r RNA microbial sequencing and gas chromatography were used to observe the abundance and diversity of intestinal microbiota and the changes of intestinal metabolite short chain fatty acids(SCFAs).The expression of inflammatory factors and β-Amyloid protein(Aβ)level in mice were determined by ELISA experiment and the effect of HDC on antioxidant activity in mice was explored.The results showed that HDC could affect the intestinal microbial structure of mice: the abundance of Firmicutes increased,the abundance of Bacteroidota decreased,the abundance of intestinal beneficial microorganisms such as Lactobacillus and Akkermansiaceae increased,and the content of intestinal metabolite SCFAs in mice feces increased significantly(P < 0.05).HDC can inhibit Aβ deposition and over activation of microglia in brain,as well as the expression of NLRP3,caspase-1 and Il-1β in intestinal tissue,serum and brain.In addition,HDC also significantly inhibited oxidative stress in mice.In HDC group,the levels of TSOD and GSH-Px increased significantly(P < 0.05),and the level of MDA decreased significantly(P < 0.05).The results of Morris water maze experiment show that HDC can alleviate memory and cognitive impairment.This study developed a kind of coffee rich in dietary fiber,and preliminarily studied its effect on AD.The results show that HDC can significantly change the intestinal microbial structure,and affect the production of intestinal metabolite SCFAs and the expression of inflammatory factors.And inhibiting the neuroinflammation and Aβ deposition in the brain,so as to improve the impairment of cognitive and spatial memory in mice.