茶乳之組成與茶湯膜濃縮

Abstract

茶乳之組成和使用茶葉種類，有極大的關係”以全發酵性的紅茶和部份發酵性的包種茶為例，前者因大部分的多元酣，在製作過程中氧化為較高分子量的聚合型態，故較易形成茶乳，且組成以該類的多元酚為主，如茶黃質（Thearlavins）及茶紅質（Thearubigins)。後者因發酵程度輕微，所形成茶乳的多元酚組成以單純的醋型兒茶素為主。且茶湯中的咖啡因是形成茶乳的重要成份。其他的化學組成包括蛋白質、果膠質及離子。在包種茶中並發現有少量的肢基酸參予。以不經相變化的逆滲透濃縮方式進行包種茶濃縮時，得知茶乳存在時，在短時間內就會形成膜淤積，造成操作效率的降低，而適度的提高濃縮溫度，除可克服茶乳對透流率的影響外，且顯著縮短濃縮時間，可得到較好的茶湯品質。 The composition of tea cream formed during tea infusion extraction varied with the types of teas used. The theaflavins and thearubigins, which are high molecular weight oxidized polyphenols, were the major phenolic compounds in black tea cream. However, simple and unoxidized polyphenols, ester-forms of catechins were the major phenolic compounds in Paochung tea cream. Caffeine was another important compound of tea cream. Protein, pectin and calcium also participated in the tea cream formation. Some of free amino acids were also found in Paochung tea cream. During the reverse osmosis concentration of Paochung tea infusion, tea cream quickly decreased the flux of infusion due to the fouling effect, Elevating the operation temperature decreased the effect of tea cream on the flux and reduced operation time, thus could obtain a high quality tea concentrate.