澄清飲料裝瓶後在儲存期間生成混濁沉澱是影響飲料品質之重大缺陷。以8-10分熟青梅浸漬糯米醋所製得之梅醋產品在室溫儲存16週後混濁度呈上升之現象,部分樣品中的懸浮顆粒會發生沉降而形成深褐色沉澱物。先以酵素分解果膠後之梅醋再以酸洗矽藻土進行抽氣過濾,混濁度可以降低至1NTU以下,色澤呈琥珀色。分析矽藻土過濾之梅醋發現單寧酸試驗(tannic acid test)引起之混濁度增加值為51.34NTU,顯示樣品中含有大量起霧性蛋白質(haze-active protein),而明膠試驗(gelatin test)引起之混濁度增加值則為0.87NTU,顯示樣品中起霧性多酚物質(haze-active polyphenol)之含量極微。以矽藻土過濾之梅醋在室溫儲存16週後混濁度會上升,顯示矽藻土過濾之梅醋會有二次混濁之現象發生。在矽藻土過濾之梅醋中添加2.5g/L皂土(bentonite)即可將樣品中之起霧性蛋白質幾乎100%移除,添加不同濃度之矽膠(siica gel)則只能移除20-45%之起霧性蛋白質。皂土處理-矽藻土過濾梅醋在室溫儲存16週後混濁度仍可以維持在1NTU以下。研究結果證實起霧性蛋白質是造成矽藻土過濾梅醋發生二次混濁的主要因子,利用皂土處理移除起霧性蛋白質能有效維持矽藻土過濾梅醋之澄清安定性。不同澄清處理之矽藻土過濾梅醋樣品經過室溫儲存16週後皆會產生極輕微之褐變。
Haze formation and precipitation are critical quality defects for clear drinks. Mei vinegars, produced from the maceration of mei fruit with rice vinegars, showed increase in turbidity and presented dark brown sediments after storing at room temperature for 16 weeks. The turbidity of depectinized mei vinegars reduced less than 1NTU and present amber color after filtered by diatomaceous earth. The turbidity of diatomaceous earth filtered mei vinegars increased 51.34NTU and 0.87NTU after tannic acid test and gelatin test, respectively, which indicate mei vinegars may contain large quantities of haze-active (HA) proteins, but only few HA polyphenols. Diatomaceous earth filtrated mei vinegars treated with 2.5 g/L bentonite removed almost 100% of HA proteins, which kept the turbidity of mei vinegars to less than 1NTU throughout room temperature storage for 16 weeks. In contrast, the same vinegars samples treated with different doses of silica gel were able to removed only 20-45% of HA proteins. Result of this studies demonstrated that HA proteins in mei vinegars were the major factor to cause haze formation during room temperature storage, and bentonite treatment was able to remove the HA proteins and stabilize the clearness of bottled mei vinegars when storage at room temperature for 16 weeks.