Screening Of The Probiotics For Alleviating Capsaicin-induced Gastrointestinal Injury And Their Preparation Of Fermented Milk

Chili peppers are vegetables and spices widely consumed in daily life.As the main pungent ingredient of chili peppers,capsaicin has demonstrated potent pharmacological effects,such as anti-obesity,antioxidant and pain-alleviating.Nevertheless,recent studies have revealed that capsaicin shows bioactivities under low doses but tends to have side effects under high doses.When capsaicin is consumed at high levels,it can cause heart-burn in the gastrointestinal tract,and even symptoms such as pain and diarrhea.However,the specific dose and damage form of capsaicin-induced gastrointestinal injury are still unclear.When people eat chili peppers,they usually mix them with other foods to relieve the pungency of the taste caused by chili peppers,but there are no studies or relevant products that can relieve the stimulation of pungent taste.Research on probiotics and gastrointestinal health suggests the great potential of probiotics in alleviating gastrointestinal injury.In this context,this subject investigated the dose-effect relationship of capsaicin-induced gastrointestinal injury in mice,so as to construct a mouse model of capsaicin-induced intestinal injury to screen the probiotics with alleviation,then speculated their mechanisms,and the best two strains of probiotics were used in the preparation of fermented milk with high viable count.The main findings are as follows:Capsaicin was used to investigate the dose-effect relationship of capsaicin-induced gastrointestinal injury.The mouse model of capsaicin-induced gastrointestinal injury was established by intragastric administration of 40,60,and 80 mg/kg/day in mice.Oxidative stress,serum neuropeptides,gastrointestinal tissue morphology and levels of inflammatory factors were determined as the main indicators to reveal the accurate dose and injury form of capsaicininduced gastrointestinal injury.The results showed that after intragastrically administrated of different doses of capsaicin for one week,40 mg/kg/day capsaicin had no significant effect on the gastrointestinal health of mice,while 60 and 80 mg/kg/day capsaicin caused inflammatory damage to the intestine,especially the ileum and colon.The serum contents of SP and CGRP are significantly positively correlated with the dose of capsaicin,and the correlation index are0.730 and 0.687,respectively.80 mg/kg/day capsaicin significantly affected the level of SCFAs and changed the structure of gut microbiota.The above results showed that capsaicin at a dose of 60 mg/kg/day or above will induce tissue lesions and inflammation in the ileum and colon of mice,change neuropeptide levels,and increase gastrointestinal pain.The mice with capsaicin-induced injury of ileum and colon was constructed by intragastric administration at a dose of 60 mg/kg/day,and different probiotics were intervened to screen the probiotics with alleviation on intestinal injury.The results showed that among 9 strains of probiotics with anti-inflammatory potential,Lactobacillus reuteri CCFM1175 and Lactobacillus paracasei CCFM1176 could effectively alleviate the intestinal injury induced by capsaicin,specifically as follows: restored the antioxidant capacity,reduced the pathological damage and pro-inflammatory factor levels in the tissues of ileum and colon,significantly increased the level of anti-inflammatory factors,and down-regulated the levels of SP and CGRP in serum and colon tissue.From the perspective of TRPV1,SCFAs and gut microbiota,the mechanism of two probiotics in alleviating capsaicin-induced intestinal injury was preliminarily analyzed.The results showed that Lactobacillus reuteri CCFM1175 was mainly involved in intestinal immunity by restoring the level of intestinal SCFAs and increasing the relative abundance of Ruminococcaceae UCG＿014 and Akkermansia in the gut microbiota of mice;Lactobacillus paracasei CCFM1176 mainly downregulated the TRPV1 expression in the tissues of ileum and colon,increased relative abundance of Ruminococcaceae UCG＿014 and Lachnospiraceae UCG＿006 in the gut microbiota,which improved intestinal homeostasis.Finally,the above two probiotics that could alleviate the capsaicin-induced intestinal injury were applied to the fermented milk.In order to improve the fermentation rate and quality of probiotics in milk,the co-fermentation method was used to prepare fermented milk with high viable counts of probiotics.The results showed that through the co-fermentation with Lactobacillus bulgaricus 5L6,the viable counts of Lactobacillus reuteri CCFM1175 and Lactobacillus paracasei CCFM1176 in fermented milk were significantly increased,reaching8.24 and 8.61 lg CFU/m L after fermentation for 12 h.The rate and fermentation quality were significantly improved.Compared with original fermentation,the co-fermented milk with probiotics had good storage characteristics and sensory scores,indicating that co-fermentation was feasible to prepare probiotic fermented milk with high viable counts and could effectively achieve the application of two functional probiotics in fermented milk.