醋,又名醯,於中國古代醫書記載有袪邪消食等作用。現今社會壓力大及作息異常下,易造成人體內乳酸與丙酮酸 (Pyruvic acid)蓄積而感覺疲憊。近期報告指出,發酵醋所含有機酸益於克氏循環 (TCA cycle)之代謝,故其保健性逐被受重視。本實驗篩選出一高產酸能力之Acetobacter pasteurianus NPUST S21後,探討並提升該菌株之產酸能力;並利用固定化方式改善傳統發酵接種之缺點,增加其方便性及應用性,並開發一種固態發酵方式。以3%之菌量接種於含2%葡萄糖、1%酵母抽出物、0.1%醋酸鈉、0.2%甘油及6%酒精、起始pH 5.0±0.5之液態培養基,於溫度33℃條件下,經轉速125 rpm振盪培養48小時後,S21產酸量達6.4% (w/v)。將玉米穗軸浸漬於酒精濃度為20%之溶液中5小時後做為菌體固定化之基質,並以基質與菌液之比例為10比6,於培養溫度30℃之條件下,以150 rpm振盪培養12小時,則能製作擁有最佳醋化率與保存性之醋醅。另於固態發酵方面,以紅高粱、蕎麥與小麥為原料,以起初含水率為50% (w/w)進行酒精發酵。當發酵物之酒精濃度達5% (v/v),以醋醅接種量30% (w/w)、間隙物質比例20% (w/w)及發酵溫度為30℃之條件進行醋酸發酵40天,經3個月之熟成後,產品以香氣分析並與市售商品進行品評試驗,其結果顯示本實驗之固態發酵醋之整體接受度高於其它市售樣品。
Vinegar, also known as xi, is regarded as the herbal medicine, which can disinfect and digestive role in China. Nowadays, many people work hard for long time and get stressful, who could easily get tired because of the accumulation of lactic acid and pyruvic acid. In the recent study reported the healthy benefits about the fermented vinegar containing organic acids which support TCA cycle. In this research, isolated the strain which had the strongest activity named Acetobacter pasteurianu NPUST S21. To improve the way of traditional fermentation starters, we use immobilization for applying, and developing the new product of solid-state fermented vinegar. The optimal medium contained 2% glucose, 1% yeast extract, 0.1% sodium acetate, 0.2% glycerol, alcohol 6%. The fermentative conditions were that medium initial pH 5.0 ± 0.5, inoculum size 3%, temperature 33℃and shaking speed 125 rpm in flask. After 48 hours fermentation, the maximum concentration of acetic acid was 6.4% (w/v). Comparing the acetification and survival rate , the best immobilized condition was that used corncobs as a substrate soaked in 20% alcohol solution for 5 hours, and immobilized the bacteria at 30℃, 150 rpm, for 12hours, respectively. In solid-state fermentation, red sorghum, buckwheat and wheat as materials, which adjusted 50% of initial moisture content and then mixed with 20% crops. The vinegar was fermented in 30℃, inoculum size 30%, for 40 days. After 3 months aging, the vinegar will be analyzed and sensory test. The results shows that solid-state fermented vinegar is better acceptance than others.