The Extraction,Characterization Of Akebia Trifoliata Var. Australis Pectin And Its Construction With Soybean Protein Complex System

Akebia trifoliata?Thunb.?Koidz.var.australis?Diels?Rehd,as a new kind of wild plant resources,is rich in pectin and has a broad market prospect.Our preliminary studies of Akebia trifoliata var.australis pectin have confirmed that the Akebia peel is a valuable pectin resource,which is worth developing and utilizing.Soy protein is one of the few vegetable protein varieties that can replace animal protein,which is low in price and strong in sustainable development compared with animal protein.In addition,diet based on soy protein has proven to be capable of preventing many diseases by reducing blood pressure,blood sugar and cholesterol levels.Although soy protein has many advantages,natural soy protein is less water-soluble near its isoelectric point,which seriously restricts its application in the food industry.Therefore,it is necessary to modify soy protein to improve its functional properties and expand the application fields.In this paper,with the Akebia trifoliata var.australis peel as main raw materials,different extraction agents?H₂O,ammonium oxalate,HCl,Na OH?were used method to extract four kinds of different Akebia trifoliata var.australis pectin by continuous extraction,and its physical and chemical properties and functional properties were determined,the difference among them was also analyzed;two different kinds of Akebia trifoliata var.australis pectin were extracted from the peel with hydrochloric acid and citric acid,and the physicochemical properties and rheological properties of this two kinds of pectin were studied;by using the extracted two pectin to improve the SP,the turbidity,potential and protein content of the solution before and after modification were compared and analyzed.This study provides theoretical support for the expansion of soybean protein separation protein and white wood pass pectin in food industrialization.The main research results are as follows:1.H₂O,ammonium oxalate,HCl and Na OH were used for the continuous extraction of the insoluble substance?AIS?.The results showed that the yield of the white wood peels was as high as 56.30%,and the main pectin was chelating soluble pectin?CSP?.CSP had the highest yield?34.78%?and the average molecular weight?4204 k Da?and the lowest galacturonic acid content?33.32%?.The Gal A results showed that the contents of water soluble pectin?WSP?,hydrochloric acid soluble pectin?HSP?and aikali soluble pectin?ASP?were 86.99%,72.30%and 97.14%respectively,and ASP had the highest content of galacturonic acid.The FTIR results showed that four kinds of pectin have the characteristic absorption peak of typical pectin polysaccharide.The MD results showed that the esterification degree of WSP,CSP and HSP were 31.30%,15.27%and 23.31%respectively.The emulsifying activity results showed that the emulsification activity of the four pectins was higher than that of the standard orange peel pectin,and ASP had the best emulsifying activity.2.Two different kinds of HEP and CEP were prepared by hydrochloric acid and citric acid,and their structural characteristics and static rheological properties were studied.The SEM results showed that the HEP structure is compact and the CEP structure is relatively loose.The FTIR results showed that both of the pectins were?-isomer D-pyranose and rich in uronic acid,and HEP had higher esterification degree than CEP.X-diffraction results show that HEP has higher crystallinity than CEP,and the lower the crystallinity,the better the solubility,so the solubility of CEP is better than HEP.The dynamic and static rheological results show that the static and dynamic properties of Akebia acid-soluble pectin?HEP and CEP?were affected by the factors such as pectin concentration,sucrose content,the species and content of metal ion(Ca²⁺,Na⁺),heat treatment time and temperature,and these factors have different effects on the two pectins.The difference between HEP and CEP may be related to their different structures.3.The soybean protein isolate was modified by using two different kinds of Akebia trifoliata var.australis pectin?HEP and CEP?.The results showed that whether in the high concentration of soy protein?SP?or under the condition of low concentration of SP,with the reduction of p H,pure SP solution showed an obvious phase separation,on the other hand,the addition of HEP/CEP could inhibit the precipitation of SP near the isoelectric point,formed a relatively stable protein-polysaccharide solution.The turbidity analysis results were consistent with zeta potential and phase diagram results.The mixing ratio of SP-HEP/CEP also affected the critical p H value,zeta potential value of soluble complex in solution and the solubility of SP in solution.Under the condition of higher SP concentration?1.00%?,the critical p H value of the soluble complex gradually shifted to a higher p H value,with the mixing ratio of SP-HEP/CEP increased from 5:1 to 20:1.And its zeta potential is smaller than the pure SP solution.The results of protein solubility and protein content also indicated that the addition of HEP/CEP increased the content of soluble protein in the solution under low p H condition.The results of this study showed that the formation of SP-HEP/CEP can significantly improve the functional properties of SP in acidic conditions.