茶渣碱提取物中的蛋白质性质分析

Study on Functional Properties of Alkaline Protein Extract from Tea Residue

茶渣的蛋白质含量较高,可通过碱提法高效获得,然而该法获得的茶渣蛋白质可能与多酚、糖类物质等发生反应,影响其在食品工业中的应用。本研究测定绿茶渣蛋白质提取物的理化性质与生理活性,对碱提法获得的茶渣蛋白质进行分析。采用酶法改进茶渣蛋白质的乳化性、起泡性、抗氧化性。结果表明,提取物中蛋白质含量为52%,其等电点(pI)为3.6,可主要分为3个组分。茶渣蛋白质的溶解度、分散性、起泡性和乳化性与溶液pH值呈正相关性。当茶渣蛋白质质量浓度为80 mg/mL时,对嗜冷菌和假单胞菌的抑菌率分别为98%和93%。经胃蛋白酶处理后,茶渣蛋白质的起泡性为58.3 mL/g,约是未处理样品的2倍。乳化性为100.0 mL/g,约是未处理样品的4倍,抗氧化性变化较小。经碳水化合物复合酶Viscozyme■ L处理后,茶渣蛋白质的起泡性提至52.4 mL/g,乳化性降至12.0 mL/g,抗氧化性提升约0.5倍。试验证明茶渣蛋白质提取物及其酶解产物具有较好的功能性质和开发新型功能性食品的应用潜力。

Tea residue contains high amount of protein,which can be cost-effectively extracted by alkali.However,the application of tea protein in food industry was limited due to its reaction with polyphenols or sugars.In this study,the physicochemical properties and bio-functionalities of the protein extract obtained from green tea residue were determined,and the emulsifying,foaming and antioxidant properties were improved by enzymatic method.The results showed that the protein content of the extract was 52%,and its isoelectric point(PI)was 3.6.The solubility,dispersibility,foaming and emulsifying properties of tea residue protein were positively correlated with the pH value of the solution;when the concentration of protein extract was 80 mg/mL,the inhibition of psychrophilic bacteria and Pseudomonas were 98%and 93%respectively.After pepsin treatment,the foaming ability of protein extract was 58.3 mL/g twice as that of the untreated sample,and the emulsifying ability was 100.0 mL/g four times as that of the untreated sample.After treatment with Viscozyme ■ L,the foaming ability of tea residue protein increased to 52.4 mL/g,the emulsifying ability decreased to 12.0 mL/g,while the antioxidant activity increased by about 50%.The results showed that the protein extracts from tea residue and their enzymatic hydrolysates had good functional properties and potential for the application in food industry.