Emulsification Properties For The Apocynum Venetum L.Tea Polysaccharide Conjugates

Apocynum venetum L.is a wild perennial herbaceous plant of Oleander family,and it is often made into tea for drinking in Chinese folk.In this thesis,the alkali-extracted Apocynum venetum L.tea polysaccharide conjugates(ATPC-A)of Apocynum venetum L.tea from Yuli,Xinjiang was extracted by alkaline extraction.Its basic physical and chemical properties were characterized.On this basis,we researched the emulsifying characteristics of ATPC-A,and the following conclusions were drawn:1.The ATPC-A contained 15 kinds of amino acids,but free amino acids were not detected by SDS-PAGE electrophoresis,indicating that the measured amino acids were composed of proteins.However,UV spectrum scanning showed that there was no characteristic absorption peak of proteins in ATPC-A,so it could be inferred that the proteins contained in ATPC-A were covalent binding proteins.The relative molecular weight of ATPC-A was determined by high performance gel chromatography.The results showed that the relative molecular weight of ATPC-A was mainly distributed around 5.5×10⁴ Da,5.38×10⁴ Da and 5.67×10³ Da.It was determined that ATPC-A contains arabinose,rhamnose,xylose,fucose,galacturonic acid,glucose and other monosaccharide components,and the molar ratios are 1.08,14.47,0.78,2.15,4.26,and 4.02.Therefore,it was concluded that ATPC-A was a pectin acid polysaccharide dominated by pyranose according to infrared spectrum analysis.2.By means of interfacial tension,viscosity,APS,PSD and Zeta-potential,the emulsification characteristics and emulsification stability of ATPC-A as an emulsifier were studied.The results showed that the addition of ATPC-A could rapidly reduce the oil-water interfacial tension.And when the ATPC-A content was 1.0 wt%?2.0wt%,the prepared emulsion had a higher viscosity than the 5 wt%GA emulsion.During storage at 25?,the APS of 2.00 wt%and 3.00 wt%ATPC-A emulsion increased from 0.47?m to 1.94?m and from 0.37?m to 1.48?m,respectively.Compared with the GA emulsion at a concentration of 5 wt%,showed better emulsification properties and storage stability.But when the storage temperature increased to 60?,the stability of the emulsion became worse.3.The emulsifying characteristics and emulsifying stability of 2.00 wt%ATPC-A emulsion under different ionic strength Na⁺(0.10 mol/L?0.50 mol/L),Ca²⁺(0.01mol/L?0.05 mol/L)and p H(2.0?8.0)were studied.The results showed that ATPC-A emulsion could resist the adverse effects of Na⁺and Ca²⁺on its stability,but as the concentration of Na⁺and Ca²⁺increased,the resisting effect gradually weakened.CLSM showed that there was a phenomenon of droplet aggregation in the emulsion,and the appearance picture of the emulsion indicated that the emulsion formed a similar"gel state".At the same time,ATPC-A could form emulsions with relatively small APS under different p H conditions,and these emulsions had good storage stability under weakly alkaline conditions.