Preparation Of Garlic Oligosaccharides And Study On Their Probiotic Activity

Garlic is a kind of plant of the same origin as medicine and food.It is widely planted in China,Sugar is one of the important functional substances of garlic,accounting for more than 75% of the dry weight of garlic.Oligofructose is an important bifidus factor,which has functions of regulating intestinal flora,promoting intestinal metabolism,and enhancing immunity.The sugar in garlic is mainly fructan,which is a good source for preparing garlic oligofructose.The annual price of garlic has changed greatly.In order to avoid waste of resources,the deep processing of garlic is a research hotspot in recent years.At present,the garlic deep processing products developed and produced at home and abroad are mainly aimed at sulfur compounds in garlic,and there are few products about garlic polysaccharides.Previous reports have pointed out that the garlic waste residue before and after the extraction of sulfur-containing compounds and wastewater contain a large amount of fructan,which can be used as a raw material for extracting garlic polysaccharide.Therefore,on the basis of extracting garlic polysaccharide by hot water extraction method,membrane separation technology was used to intercept polysaccharides with different molecular weights,and used as carbon source to explore the proliferation of probiotics by different molecular weight polysaccharides.The polysaccharides with the best molecular weight range of probiotics were added as the target,and the changes of their contents in the process of acid hydrolysis and enzymatic hydrolysis were explored.Based on the change rule of target polysaccharides,combined with membrane separation technology,a continuous preparation separation system was established.This study can realize the comprehensive development and utilization of garlic polysaccharide,and play a role in improving the quality of garlic.The main findings are as follows:1.The garlic polysaccharides with different molecular weights were isolated and the proliferative effects of probiotics in vitro were studied.Proliferation experiments of Bifidobacterium longum,Bifidobacterium lactis,Lactobacillus plantarum and Lactobacillus fermentum were carried out with different molecular weights of garlic polysaccharide as carbon source.As the molecular weight of polysaccharide increased,the pH drop and OD value of probiotic culture medium increased.Decrease,the garlic polysaccharide with molecular weight of 300-1000 Da has the best proliferation effect on bifidobacteria and lactic acid bacteria2.Study on the acid hydrolysis of garlic polysaccharides.By measuring the degree of hydrolysis and oligosaccharide content in the hydrolysis of garlic polysaccharides,hydrochloric acid was selected at pH=3,the temperature was 70 °C,and the substrate concentration was 5%.Hydrolysis of garlic polysaccharide under the acid hydrolysis condition is most beneficial to the accumulation of garlic oligosaccharides.3.Inulin was digested with inulin to determine the changes of reducing sugar and oligosaccharide content during enzymatic hydrolysis.After 20 h of enzymatic hydrolysis,the ratio of reducing sugar to total sugar was less than 1%;the highest content of oligofructose in enzymatic hydrolysis was 0.17 mg/mL.Compared with the acid hydrolysis of garlic polysaccharide,acid hydrolysis can obtain more oligofructose than enzymatic hydrolysis.4.Design a continuous preparation system for garlic oligofructose.The process and equipment for the continuous preparation system of garlic oligosaccharides were determined by combining the hydrolysis law of garlic polysaccharide with membrane separation technology.