Verification And Analysis Of In Vitro Antioxidation Activity Of Main Ingredients In Cocoa Polyphenols

Cocoa (Theobroma cacao) is a kind of delicious food with long history. It contains abundant fiber, protein, carbohydrates, minerals, vitamins and polyphenols. Polyphenols are considered the main function compounds with complex component and high bioactivity. However, up to now there are few researches on cocoa polyphenols in China. The detection methods of total polyphenols and different kinds of phenolic compound were developed in this study, Moreover, free radical scavenging test in vitro and quantum chemistry evaluation of antioxidant ability were also examined. The main results are as following:1. Establishment and comparion of total polyphenols content detection methodFolin-Ciocalteu and Ferrous Tartrate were selected as two chromogenic agents, gallic acid (GA) and proanthocyanidins (PC) were set as standard to develop the measuring method for total polyphenols. The results showed that the content of total polyphenol detected by Folin-Ciocalteu was higher than that of by Ferrous Tartrate when the same standard was used. While using the same chromogenic agents, the result using PC as standard was30.5%～54.8%higher than using GA. Moreover, the content of PC, main composition of the polyphenols in cocoa, was higher than that of total polyphenols using Ferrous Tartrate method, which is unreasonable. There is no GA found in the sample. According to all above results, we chose Folin-Ciocalteu method and PC as standard.2. Detection of phenolic compound in coca extractThe total polyphenols in industrial extract, trial extract, export sample and cocoa beans were70.21%,56.48%and19.04%8.30%respectively. PC was main compound in coca polyphenols with content of34.51～100%according to the HPLC rssults, the content order of four sample was trial extract> industrial extract> export sample> cocoa beans. In addition, minor amount of catechin (C), epicatechin (EC), chlorogenic acid and scopolamine hydrobromide were detected.3. Antioxidant capacity of cocoa polyphenolsDPPH and ABTS method showed equal capacity of scavenging free radical for Coca polyphenols. The capacity of antioxidation was listed as EGCG> PC> trial extract> industrial extract. The EC50of PC on DPPH was47.71μg/mL, which was closed to VC and one time higher than that of EGCG.4. Evaluation of the antioxidant capacity of polyphenols by quantum chemistry calculationEvaluating the antioxidant capacity of main composition of cocoa polyphenols like EC(C), chlorogenic acid and scopolamine hydrobromide, together with possible ingredient such as PC-A2、B2、B3by PM6method, we got the results that PC had higher antioxidant activity than that of catechins and other phenolic compounds in coca extract. The antioxidant capacity had relationship with the kind of monomer and monomer connection mode, and was direct proportion to the degree of polymerization.