Optimization Of Extraction Process Of Carrot Polysaccharide And Its Ultrasonic Modification

With the development of the times,human also pay more attention to health of the diet,and the food industry is studying the latest health food constantly.Carrot as a daily food has a variety of effects,including lower blood pressure,reduce the incidence of heart disease,prevent hardening of the arteries,enhance the immune function of the body,be good for liver and eyesight,also purge detoxification and so on.As a result,carrots are valued by researchers as a worthwhile vegetable.Polysaccharides are the main chemical composition of carrots with anti-tumor,anti-oxidation,hypoglycemic,hypolipidemic and other biological activity.In order to make the carrot polysaccharide better absorbed by the body,the best way is to its ultrasonic modification.The experimental contents of this experiment are as follows:1.Extraction of carrot polysaccharides by Microwave-assisted Extraction.Use microwave oven to extract by microwave from carrot powder as raw material.By controlling the factors such as power,time and solvent ratio,the single factor condition is optimized,and then the optimal process parameters are obtained by orthogonal test.The results showed that the optimum extraction rate of carrot polysaccharide was 4.06% when the extraction power was 560 W,time 35 min and the ratio of material to liquid was 1:20.2.Determine physicochemical properties and molecular weight of carrot polysaccharides extracted by microwave.Physicochemical properties and molecular weight of the carrot polysaccharide was measured.The results showed that neutral sugar content and uronic acid content in carrot polysaccharides are 60.71 ± 2.1% and 51.21% ± 2.16%,found that it does not contain starch by potassium iodide reaction and detected by HPGPC measured to obtain a molecular weight of 2.84 ×105.And compared with the SEM apparent image of the polysaccharide by the hot water extraction and microwave extraction,it was found that the microstructure of the polysaccharide was destroyed and the lamellar structure was smaller.3.The in vitro antioxidant properties of carrots polysaccharides extracted by hot water and microwave assisted extraction were investigated.The ability of DPPH free radical scavenging activity and inhibition of ABTS~+ and iron ion reduction was compared.The results showed that the effect of two kinds of polysaccharides on DPPH was the same;the inhibition of ABTS of the carrot polysaccharide by microwave extraction is slightly better than the other by hot water extraction;the reduction ability of polysaccharide by microwave extraction for iron ions is higher than by hot water extraction.4.Study on ultrasonic modification and structural characterization of carrot polysaccharide.By controlling sonication power,time and sample concentration,the polysaccharide was sonicated.And the physicochemical properties and structural characterization of polysaccharides were measured after the treatment.The results are as follows: the molecular weight of the polysaccharide roughly stabilized at 2.70×10~5-2.80×10~5 after treatment by ultrasonic;carrot polysaccharides are mainly composed of galactose and galacturonic acid and the neutral sugar content decreases with increasing ultrasound conditions but the uronic acid increases.Analysis by infrared spectroscopy revealed that it contained carboxyl and aldehyde groups,so it indicated the presence of uronic acid.The pictures of SEM show that ultrasound will affect the apparent structure of polysaccharides,so that the sheet structure is smaller.