Characteristics Study Of Pectin From Apple,Hawthorn And Application In Fermented Milk

Pectin is a kind of extremely complex polymers with diverse structure which mainly existed in the middle between cell walls and the primary cell walls.Pectin is the metrical polysaccharide of cell wall.Pectin has many functions,including regulate blood sugar level,degrade cholesterol,and improve the intestinal microbial environment and so on.Pectin has extensive sources and special gelling and rheological properties.In this article,pectin was extracted from ?Fuji apple? pomace,fermented hawthorn wine residues and steeped hawthorn wine residues.The physicochemical properties of pectins and their influence in the quality of fermented milk were studied.(1)Separation,purification and properties of apple pectin Apple pectin(AP)was extracted from ?Fuji apple? pomace,in which the pectinases had been inactivated by hot-compressed steam,followed by purification using ethanol washing and dialysis.The yield and Gal A content of the AP were 15.42% and 83.14%,respectively.In order to investigate the physicochemical properties of the AP,comparisons were made with commercial pectin A(CP-A)and B(CP-B).The esterification of AP(DE,82.76%)was higher than that of the CP-A and CP-B,which was confirmed using Fourier Transform infrared spectroscopy(FT-IR)analysis.The Mw of AP,CP-A and CP-B were 698 k Da,623 k Da and 433 k Da respectively.In texture analysis,AP demonstrated the highest gel rupture strength,confirming its better gelling properties.All three pectins exhibited shear-thinning properties under steady-shear rheological conditions,with more elastic-solid characteristics(G‘ > G?)as the concentration and frequency increased;this was especially true for the AP.Furthermore,in contrast to the CP-A and CP-B,AP maintained its viscosity at relatively high temperatures.Our results suggest that AP has great potential for use as a thickener and stabilizer in food processing,especially at higher temperatures and p H values.AP also exhibited superior thickening and stabilizing properties at lower concentrations.AP is suitable for application in the food industry in a variety of gel products.(2)Separation,purification and properties of hawthorn pectinPectin was extracted from fermented and steeped hawthorn wine residues powder,in which the effect of fermentation process on properties of pectins was investigated.The yield of fermented hawthorn pectin(FHP)and steeped hawthorn pectin(SHP)were 14.00% and 19.39%,while galacturonic acid content(Gal A)was 83.23% and 90.25% respectively.The degree of esterification(DE)of FHP(DE,71.02%)was lower than that of SHP(DE,76.69%).Both of the two pectins were defined as high methoxyl pectin(HM).The Mw of FHP and SHP were 286 k Da and 295 k Da respectively.X-ray diffraction(XRD),scanning electron microscope(SEM)and differential scanning calorimetry(DSC)analysis all showed differences which probably due to the fermentation process.FHP and SHP solutions both exhibited shear-thinning properties which was caused by random coil of pectin polysaccharide and FHP tended to be more elastic-solid characteristics(G‘ > G?)as the concentration and frequency increased,which was not reflected in SHP.Our results suggested that the fermented and steeped hawthorn wine residues powder can be used in extracting pectins with different properties,and both of the pectins has great potential for use as a thicker and stabilizer in food processing.The fermentation process greatly enhanced the elastic-solid characteristics of FHP.Compared to the apple pectin,hawthorn pectin is more suitable for application in fluid food as thickening and stabilizing role.(3)The effect of pectin on the quality of fermented milk Different kinds and gradient of pectin were added to the fermented milk formula,and we obtain solidified and stirred fermented milk after sterilization,fermentation and cold storage(or cold storage after stirring)process.AP and CP-A both showed best promotion when the volume of addition was 0.1%,excessive amount of AP and CP-A will have negative effect on quality of fermented milk.The addition of FHP and SHP positively correlated with the quality of fermented milk,fermented milk both got the highest gel intensity and consistency when adding the largest amount of 0.2%.SHP has especially significant effect on improving the quality of fermented milk.The effect of FHP is a bit weaker,which only improve the quality of fermented milk under high volume of addition.