| Abstract: | 以不同稀釋比例(v/v)、添加15 %(w/v)不同碳源及1 %(w/v or v/v)有機 酸之稀釋鳳梨汁基質作產量比較時,除了以1：9(v/v)稀釋比例產量顯著下 降外,其餘稀釋比例之產量無明顯差異;在碳源中,以添加蔗糖或葡萄糖者, 可得較高之產量;而有機酸中,則以添加醋酸佳。以不同蔗糖添加量( 0、7.5、15、22.5 及30%,w/v)及醋酸添加量(0、0.5、1.0、1.5 及 2.0%,v/v)之1：7(v/v)稀釋鳳梨汁基質作產量比較時,發現可得較佳產量 之添加量分別為7.5∼15.0% (w/v)之蔗糖及1.0∼1.5% (v/v)之醋酸,可得 較佳產量,然於上述添加量範圍內,纖維素膜產量並無顯著差異。此後以 1：7(v/v) 稀釋比例、添加 7.5% (w/v) 蔗糖及 1.0% (v/v)醋酸為基質, 於不同溫度(25、30及35℃)下進行醱酵,結果以 30℃可得最高之纖維素膜 產量;於此溫度下,經醱酵 9天後,即可達最高乾重產量之95.52% 。以不同 基質深度(1.3、 2.1、4.2、6.2及 7.0 cm) 作產量比較時,則顯示以 2.1∼4.2 cm 之基質高度時可得較佳之產量。於不同培養天數(9、12 及 15 天)所得纖維素膜之物性(含水量、離水性及保水性),彼此間並無顯著 的差異。而於質地性狀(彈度、凝聚度、咀嚼度、附著度、硬度、破碎度 及緻密度) 方面,則以培養 9 天所得之纖維素膜和進口商品(以椰水為醱 酵基質)最為相近,且較進口商品有較高之感官評估接受度。
Acetobacter xylinum A-5 isolated from Kobucha was inocu- ated into pineapple juice to study the effect of substrateomposition and cultivating conditions on the yield of bacte-ial cellulose. Studies on the effect of dilution ratios ( 1:1∼1:9,v/v)added various sugars (15%, w/v) and organic acids (1%,v/v or/v) on the yield of cellulose indicated that A. xylinum A-5roduced higher cellulose yields in diluted substrates (1:1∼1:) with added acetate and glucose or sucrose than in substratesith all other dilution ratios and added components. Various amounts of sucrose (0∼30 %, w/v) and acetic acid0∼2.0%,w/v) were added to 1:7 diluted pineapple juice substr-te to compare their effects on the cellulose yield. Resultshowed that higher yields were obtained when 7.5∼15.0 % and.0∼1.5% of sucrose and acetate, respectively, were added tohe substrate. However, the cellulose yields between the abovedded ranges were not significantly different. Results from the effects of incubation temperatures(25∼35J)and substrate depths (1.3∼7.0 cm) showed that the best harv-st of cellulose is on the condition of 30℃ incubation and sub-trate depth of 2.1∼4.2 cm. Moreover, 95.52 % of the total cel-ulose yield was reached after 9 days of incubation at 30℃. There was no significant difference in physical propertiesmong cellulose pellicles obtained from different fermentationeriods. The textural properties of cellulose pellicle from theth day of fermentation was found to be similar to that of thewo commercial products ( Nata de coco ) and had a better senso-y acceptability. |
