Effects of deastringency treatments with CO2 on composition, yield and physicochemical properties of pectin extracted from persimmon cell wall

ObjectiveThe present study compared difference of pectin composition in persimmon cell wall at different deastringency degrees by CO2, analyzed the effects of deastringency treatment on extraction yield and physicochemical properties of persimmon pectin, in order to provide technical support for efficient extraction and application of persimmon pectin. MethodJinping persimmon was subjected to deastringency treatment through four experiments: no deastringency treatment, deastringency treatment with 90%-95% CO2 for 15,24,40 h and placed at ambient temperature for 24,24,48 h. Folin-ciocaileu method was used to detect content of soluble tannin and condensed tannin. Polygalacturonic acid method was chosen to detect the pectin composition in cell wall. Pectin was extracted by ultrasound-assisted acid method. Physico-chemical properties of the extracted pectin were investigated, including pectin yield, color, polygalacturonic acid content, esterification degree and monosaccharides compositions. ResultAs deastringency time extended, content of soluble tannin decreased, content of condensed tannin increased, water soluble pectin decreased at first and then increased while chelator soluble pectin and acid soluble pectin showed the opposite tendency in the process of deastringency. With increase of deas-tringency degree, extraction yield of pectin increased,pectin yield of persimmon with 90%-95% CO2 treatment 40 h fol-lowed by being placed at ambient temperature for 48 h was 4.00 times as that of untreated persimmon. The lightness L* of extracted pectin decreased significantly(P<0.05,the same below), polygalacturonic acid content increased significantly. The pectin extracted was high methoxyl pectin, contained rhamnose, arabinose, galactose, glucose, xylose and galacturonic acid. As deastringency time prolonged, relative percentage of arabinose and xylose decreased, but that of galacturonic acid increased. ConclusionDeastringency treatment with CO2 can significantly increase extraction yield of pectin , affect physicochemical properties of pectin, hence it can be taken as pre-treatment in production of persimmon pectin. Deastrin-gency treatment with 90%-95% CO2 for 40 h and put in ambient temperature for 48 h can produce the pectin with optimal quality.