| In the process of litchi processing and consumption,litchi shell is usually discarded dir ectly as waste,which results in waste of resources.The polysaccharide components of li tchi shell has the biological activity function of immune regulation,anti-tumor,loweringb lood sugar,reduce blood lipid,anti-radiation,anti-virus,anti-inflammatory,anti-fatigue,anti-a ging,if the polysaccharide components of litchi shell can be extracted efficiently,it is of great significance for increasing the added value of lychee products,extending the indu strial chain,saving resources and protecting the environment.Therefore,this experiment re spectively carried out water extraction and freeze-thaw assisted extraction of polysacch aride of litchi shell research,explore the influence law of influencing factors on extract ion effect,on the basis of single factor test,response surface optimization analysis result s in the optimal process parameters,and conducts the numerical simulation of polysacc haride extraction process.1.The influence of extraction temperature,water-material ratio,extraction time and extraction times on the extraction effect was studied by water extraction experiment.The results shows that the extraction rate reached the maximum when the ratio of water to material was15:1.The extraction rate reached the maximum when the extraction frequency was selected to extract 1 time,the extraction time was 90 min.The extraction rate reached the maximum when the extraction temperature 60℃.On this basis,the response surface analysis concludes the optimal process parameters as follows:extraction temperature 63.50℃,water ratio of15.73:1,the extraction time of 93.01 min.The theoretical value of extraction rate predicted by regression model was 0.746%.According to the numerical simulation results of Matlab17 software,the correlation coefficient between the prediction curve and the test curve of extraction temperature,water-material ratio,extraction time and extraction times are greater than 0.9,which can accurately predict the extraction process of polysaccharide of litchi shell by water extraction,and the model can reflect the whole extraction process.2.The influence of thawing temperature,freezing times,freezing temperature and water-material ratio on extraction efficiency was studied by freeze-thaw assisted method.The test results shows that the shell extraction yield of polysaccharide in frozen temperature was20℃,extracting effect is better;When the ratio of water to material was 25:1,the extraction rate of polysaccharide was the highest.Polysaccharide was frozen twice and the extraction rate reached the maximum.When thawing temperature selected 50℃,polysaccharide extraction yield the best.The response surface analysis concludes the optimal process parameters as follows:freezing temperature 20℃,thawing temperature 48.86 ℃,water ratio of22.88:1,frozen times 1.98 times.The theoretical value of extraction rate predicted by regression model was 0.831%.According to the numerical simulation results of Matlab17 software,the correlation coefficient between the prediction curve of freezing temperature,water-material ratio,thawing temperature and freezing times and the test curve are greater than 0.9,which can predict the polysaccharide of litchi shell extraction process accurately by freeze-thaw assisted method,and the model can reflect the whole extraction process.The above results can provide experimental basis for the development of polysaccharide of litchi shell. |
