Studies On Selection Of PPO Enzyme Source And Preparation Of Tea Pigments By Enzymatic Method

Tea pigments which include theaflavins (TFs), thearubigins (TRs) and theabrown (TB) are a group of oxidative products of tea polyphenols (mainly catechins), general formed in black tea. Tea pigments have remarkable effects on medicine. The content of tea pigments from black tea is low, whose efficient compound (TFs) is especially low; Compared to the tea pigments from black tea, the content of TFs of tea pigments prepared by enzymatic oxidatic was higher; It made industrialization of tea pigments prepared by enzymatic oxidation difficult due to inhibition of season and cost.In this paper, different plant materials were extensively explored in order to research suitable PPO sources, which would be of great help to the preparation of tea pigments. Studying on the preparing technology of tea pigments by means of enzymatic oxidization of tea polyphenols will play an important role in the industrialization and the medical research of tea pigments.The preparing methods of polyphenol oxidase (PPO) were studied. The results showed that when the adding amount of PVPP and extracting temperature were the same, homogenate buffers and pH value had greater effects on enzyme activity. It was helpful to extract enzyme by using homogenate in citrate-phosphate buffer; The enzyme activity extracted from pH5.6 buffer is higher than that of pH5.8.The loss of enzyme activity of this zymin is better, but easily used in manufacture. The enzyme activity was compared by kneeding broken-colored and enzyme oxidase. The results showed that the PPO activities in apple,melburry,mushroom and gaocha were (chosen catechol and tea polyphenol as substrate) better.The optimum pH of PPO from six materials was investigated. The results showed that tea polyphenol as substrate, the optimum pH of PPO: apple(5.6), pear(7.2) , mushuroom(6.8), melburry(7.0), gaocha(5.2); catechol as substrate, the optium pH of PPO: apple(6.0), pear(6.0), mushuroom(6.0), melburry(7.0), gaocha(5.2).The activity variation of different PPO enzyme powder in stockpile was studied.The result showed that activities of several materials declined, but the degree was not the same.The catechol and tea polyphenol as substrate the activity variation (decliation) is the same, as follows: mushroom, pear, tea, apple, gaocha, melburry; when the substrate was different, the PPO activity from mushroom and mulberry varied greatly.The PPO isoenzymy from different materials was anaylized. The results showed that when catechol as substrate, PPO isoenzymy bands of pear, apple and melburry are close to that of tea. And diversity of mushroom and gaocha isoenzymy little; Pyrogallol as substrate, the isoenzymy bands of others are unclear except that of tea, mushroom and melburry.The effect of pyrogallol as sustrate is better than that of catechol as substrate.The tea pigments prepared by enzymatic oxidation from different materials and different extracting method were studied. The results showed that the effects from tea, apple and pear PPO preparing tea pigments were better. Tea as enzyme liquor and pear zymin and enzyme powder as apple preparing tea pigments were good. The yield of pigments prepared by tea,apple and pear PPO were 313.5mg·g-1, 342.35 mg·g-1和114.55 mg·g-1. The total contents of TFs and TRs were 676.22mg·g-1, 89.78mg·g-1 and 37.28 mg·g-1. The conversion of products per enzyme activity were 13.17mg·g-1·μ-1, 19.27mg·g-1·μ-1and 8.37mg·g-1·μ-1.