農業部-水產試驗所全球資訊網農業部-水產試驗所全球資訊網

本研究以龍鬚菜 (Gracilaria) 做為生質酒精之原料，探討最佳水解條件與利用發酵生產生質酒精之情形。結果顯示，以乾重10.0%固形物的龍鬚菜進行酸水解，水解條件為0.5 N的硫酸於121 ℃下水解60 min 可得最佳可發酵醣含量。水解液經HPLC分析顯示，大部份龍鬚菜水解產物為半乳糖 (galactose, 20 ~ 27 mg/mL) 及葡萄糖 (glucose, 2 ~ 5 mg/mL)；不過亦出現抑制酒精發酵的呋喃(furan) 衍生物5-hydoxymethyl furaldehyde (HMF) (4 ~ 6 mg/mL)，但無furfural。以氫氧化鈉、氫氧化鈣及氧化鈣進行超鹼處理 (overliming)，結果顯示HMF均可減少50% 以上。超鹼處理後之水解液以38株酵母進行酒精發酵，結果得到最佳發酵之菌株為B4 (10.0 g/L) 與B10 (8.3 g/L)。進一步試驗觀察發酵時間，結果在發酵第七天的酒精產率可達到最高 (8.7 g/L)。估算乾基龍鬚菜之酒精產率約為13 ~ 16%。

Gracilaria sp., a red alga, was used as the material to produce bio ethanol. The hydrolytic processes for sugar conversion and yeast fermentation conditions were tested. The process of the highest amount of fermentable sugars obtained was that 10.0% Gracilaria (w/w, dry base) was prepared in a 0.5 NH₂SO₄ solution and then autoclaved for 60 min at 121 ℃. High performance liquid chromatography (HPLC) analysis showed that most hydrolysate were galactose 20-27 mg/mL, glucose 2-5 mg/mL, and 5-hydoxymethyl furaldehyde (HMF, an ethanol fermentation inhibitor) 4-6 mg/mL, and there was no fufural (also an ethanol fermentation inhibitor) found in the HPLC profile. The hydrolysate was further treated with overliming by adding sodium hydroxide, calcium hydroxide, or calcium oxide. Results showed that the HMF in the hydrolysate reduced to less than 50% with each of the treatments. The overlimed hydrolysate was then prepared as media for the test of 38 different yeast strains to produce ethanol. It was found that the competent strains were B4 and B10, which could produce about 10 and 8 g ethanol per liter, respectively. Futher observation of the fermentation time, a highest yield of ethanol (8.7 g/L) was achieved in a batch culture at the 7th day. The ethanol producing ratio of Gracilaria hydrolysate was around 13-16%, while converted and calculated based on the dry base (w/w).