Study On Pectin’s Physical Property And Structure From Actinidia Residue

Pectin is mainly in fruits and vegetables. It can be used as thickener and binder in food industry, improving the commercial value of food. In recent years, Scientists believed that pectin was a kind of soluble dietary fiber to promote intestine movement for health because of its imbibition. In this research, the physical and chemical properties of actinidia pectin, especially its characteristics of non-Newtonian fluid and senior molecular structure, were studied.1Compared with the basic physical properties of pectin1(freezing) and pectin2(hotting), pectin chrominance, such as brightness (whiteness), yellowness, redness and evenness, was tested. Whatever drying method, pectin color was range of milky to shallow yellow. And its evenness was consistent. In addition, the bright of pectin1was lighter, while pectin2was more yellow because of pyrogenetic reaction. Both pH values were3.16±0.015and3.39±0.015, respectively. Their D-galactose contents were48.6%±0.78%and33.05%±0.59%, respectively.2Two actinidia pectins were pseudoplastic non-Newtonian fluid. Their flow curves were followed as Newton’s power law equation with the shear thinning phenomenon,ηp1=7.112×r0.641-1and ηp2=3.274×r0.822-1. The pectin viscosity was opposite to temperature and followed Arrhenius equation, ηp1=0.0194e10.089/RT and ηp2=0.1922e4517/RT. Compared both of them; the pectin1viscosity was more than that of pectin2.3After purified actinidia pectin by DEAE-cellulose, three components were gotten, named as AP-N (5.3%, neutral), AP-Al (84.8%, acid) and AP-A2(9.9%, acid). Triple of them, AP-Al content was mostly. Their molecular weight was281.89kDa,524.31kDa and273.87kDa by HPGHC, respectively. In AP-N and AP-A2, they also contained the small molecular weight of sugar, as7.06kDa and7.13kDa by HPGHC, respectively. Analyzed AP-Al component by HPLC-ion, it was suggested that AP-Al was composed of polygalacturonate and xylan with the ratio of3:1.4Identified AP-N, AP-Al and AP-A2senior molecular structures by infrared spectroscopy (IR), all of them contained C-C backbone in district of the secondary structure and assigned to polysaccharide. Although, there were three special domains for pectin in AP-Al, as C=O and symmetric and asymmetric-COO. AP-N and AP-A2had no C=O group so that they were assigned to atypical pectin polysaccharide. In fingerprint region, there were three stretching vibration in AP-Al at1010-1110cm-1, these domains were identified pyranose. Another stretching vibration at770-840cm-1was assigned a-glycosidic bond. Therefore, AP-A1was poly-pectin, composed of D-xylose and D-galactose. AP-N and AP-A2had one stretching vibration at1010-1110cm-1and another at890-916cm-1as β-glycosidic bond. And the same time, AP-N had also a-glycosidic bond. So both of them belong to oligosaccharides.