Studies On Separation, Purification, Stability And Antioxidation Of Proanthocyanidions From Episperm Of Tea Seeds

Procyanidins , which is widely distributed in nature, is one kind of polyphenols by the condensation of a different number of monomer flavan-3-ol or flavan-3,4-diol polymer. It has strong anti-oxidation free radical scavenging ability, and variety of biological activities. It is an efficient, low toxicity, high bioavailability natural substances. Episperm of tea seeds that contains many chemicals like the procyanidins etc, is the testa of tea (Camellia Sinensis) seeds. To make further use of the rich resources of theEpisperm, this paper studied the separation, purification and discussed the difference about the stability and oxidation resistance by compared with other plants'procyanidins and commonly used food antioxidants, then provided a reference for further development and utilization of procyanidins, also offered theoretical and practical basis for industrial production.The results showed that: Episperm of tea seeds was dried after plucking in early maturity had highest levels of procyanidins. Extracted the tea seeds procyanidins with 60% ethanol after skimming by petroleum ether and got it concentrated, then extracted by ethyl acetate and n-butanol, and finally screened by the AB-8 macroporous resin adsorption and using different concentrations of ethanol to wash off. The results showed that: eluted by 50% ethanol after extracting by n-butanol and then used TLC to expand, expand system was: V (toluene): V (acetone): V (acetic acid) = 2.85:3.15:1, the reagent was 1% of vanillin methanol solution. Using established HPLC detection of procyanidins to analyze the derived products, the result determined that the composition had the same peak time to the procyanidins B₂ standard sample, and the compared peak area was 92.63 %, it showed the purity of procyanidin B₂ was high.The drying treatment is carried on to dry episperm of tea seeds procyanidins by the methods of vacuum drying, freeze drying, spray drying .etc, to analyze and compare the content of procyanidins and the average degree of polymerization. The results showed that: the smallest average degree of polymerization was under freezing drying treatment, which was 2.65; content of procyanidins was high under spraying drying treatment, which was 535mg/g. Considering the differences in results, therefore, freeze-drying and spray drying were suitable in the extraction preparation process of procyanidins.Using these episperm of tea seeds procyanidins as tested samples which were dried under different drying treatment, and taking grape seed procyanidins as reference standard, also Vc and TBHQ as comparison to study the scavenging ablity to DPPH^·and O²-·, the results showed that: The antioxidant activity of episperm of tea seeds procyanidins was related to their degree of polymerization under the same concentration. Episperm of tea seeds procyanidins had low polymerization degree under the freezing drying treatment, the scavenging ablity to DPPH·, O²-·was higher than vacuum drying and spray drying, which were 88.12%, 36.78% in the concentration of 0.01 mg/ml, respectively. It had little different from the reference substance in the scavenging abilities, and specifically it's higher than ascorbic acid but lower than TBHQ.Also, the anti-oxidation effects of procyanidins to linoleic acid system had been studied .The results showed that: in the linoleic acid system, the inhibition ability of episperm of tea seeds procyanidins increased with the increasing of concentration during 0.005-0.1 mg/ml range but decreased with the increasing of concentration during 0.1-1.0 mg/ml range under the spraying drying treatment, this trend counted on the analysis of procyanidins dose to some extent.All results showed that the freeze drying treatment would be a good choice in the drying of episperm of tea seeds procyanidins. It had some guidance in the comprehensive application of procyanidins.The stability of procyanidins had been studied under different lighting conditions, pH, temperature, metal ions, food additives. The results showed that: Procyanidins was quite stable under a low temperature and pH; but the stability would decrease when the temperature and pH values increased. The content of episperm of tea seeds procyanidins would decrease under light, and the light led the loss of the degradation of procyanidins. The metalions as Cu²+, Fe³+ and Sn²+ had the most significant effect for the stability of procyanidins. The stability of procyanidins had been reduced by ascorbic acid, sodium benzoate,β-cyclodextrin, glucose, citric acid and other food additives, and it's the turning point when the contents of food additives were 0.3%, 0.1%, 0.3%, 0.3%, 0.7%. Vc and glucose can improve the stability of procyanidins under the optimum concentration.