天然抗氧剂茶多酚的提取及其在食品保鲜中的应用

【作者】 蒋建平；

【导师】 汪秋安；

【作者基本信息】 湖南大学 ， 有机化学， 2003， 硕士

【摘要】 本论文的工作围绕茶多酚的提取、分析和应用展开，主要内容如下： 系统地研究了茶多酚的提取过程。首先研究了不同因素对茶多酚浸出情况的影响，正交实验选择合适的浸提条件为：用60％乙醇-水溶液在70℃浸提茶叶末2次，每次20min，投料比为1：20，茶多酚的最终浸出量可达茶叶干重的22.5％。研究了实验装置和过滤过程对茶多酚浸出的影响，结果表明，采用通入N₂和装上冷凝管的装置以及趁热过滤能提高茶多酚浸出率。 其次研究了金属离子沉淀法提取茶多酚的条件，通过反复实验，最终选择以Al³⁺+Zn²⁺为复合沉淀剂；HCl转溶，茶多酚的产率提高到11.8％，纯度达到99.5％。 对样品进行红外扫描得到的红外谱图具有1610cm^-1、1510cm^-1的苯环吸收，1200cm^-1、1020cm^-1及820cm^-1左右的吡喃环吸收及3400cm^-1左右的酚性羟基吸收等吸收谱带，与儿茶素EC的标准谱图对照，证明其有2—苯基苯并吡喃的基本结构。 在前人工作的基础上运用高效液相色谱（HPLC）对茶多酚进行了分析，与标准品色谱行为对照表明，样品含有（-）-表没食子儿茶素没食子酸脂（EGCG）、（-）-表儿茶素（EC）、（+）-儿茶素（+C）三种儿茶素，并定量测定了样品中EGCG、EC和+C的含量。 将茶多酚作为天然食品抗氧化剂应用到冷却鲜猪肉的保鲜，实验通过测定冷却鲜肉（于4±0.5℃条件下保存）在贮藏期间感官品质、微生物和理化指标，来评价保鲜效果的好坏。结果表明：与不加茶多酚的冷却肉比较，单独添加0.03％茶多酚的冷却鲜肉，其细菌总数、挥发性盐基氮（TVB-N）值和过氧化值（POV）值都有明显降低，货架寿命延长，但同时也有轻微失色现象发生。实验中首次发现，将0.01％茶多酚、0.01％V_E和0.01％V_C联用同时添加到肉样中，不但抗氧化和防腐效果好，而且茶多酚引起的失色现象也得到一定的抑制。更多还原

【Abstract】 The thesis focused on extraction, analysis and application of tea polyphenols(TP)as follows:Systemic study on the extraction of tea polyphenols was carried out. Firstly, the influence caused by some factors on TP leaching rate was studied. The orthogonal experiment showed that the optimum condition of leaching TP was- 60% ethanol as solvent, under 70℃, the ratio of tea and solvent is 1:20, leaching 2 times and 20minevery time. Under the conditions ,the maximum leaching rate of TP reached the 22.5% of tea. The influence of experiment equipment and filter process on TP leaching rate was studied. The result showed that filtering when solution was hot and using the equipment with condensator and N2 could benefit enhancing the rate of TP leaching. Secondly, the condition of extracting TP by depositing TP with metal ion was studied. Through repetitious experiment, the optimum condition of precipitation method was Al3++ Zn2+ as precipitator ,dissolving precipitation with HC1. With this conditions ,the yield and purity of TP was improved to 11.8% and 99.5%.Infrared spectra showed absorption as following:benzene absorption at 1610cm-1, 1510 cm-1 , pyrones absorption at 1200 cm-1, 1020 cm-1 and 820 cm-1, and phenol hydroxy absorption at about 3400 cm-1. Compared with the standard spectra of catechin EC ,it could be certified that its frame included 2-phenyl-benpyrones. On the basis of previous work, TP was analyzed by HPLC. Compared with standard samples , EGCG, EC and +C were inspected out in TP sample and we quantitatively determined the content of EGCG, EC and +C in TP sample.TP was used as natural food antioxidant to preserve chilled pork, and the effect was appraised by determining the sensory quality, microbial and physichemical value under 4±0.5℃. The results showed that 0.03%TP could lower the value of total quantity of bacillus, total volatile basic nitrogen(TVB-N) .peroxide value (POV) and prolonged the shelf-life of pork when compared with no addition sample , but also could discolor pork. It was remarkably and significantly discovered that 0.01% tea polyphenols, 0.01%VE and 0.01%VC added to chilled pork could not only reduce value of total quantity of bacillus, TVB-N and POV, but also could restrain discolour.更多还原