Abstract
This experiment was carried out to stimulate lactic starter culture for yoghurt manufacturing. A each of 1.5% of Bios 2000, CR starter medium, and Yeast extract were added to bulk medium, acidity, pH and changes in the number of lactic acid bacteria were investigated at, intervals of two hours for Lactobacillus bulgaricus and four hours for Streptococus thermophilus and Lactobacillus casei. The results obtained were summarized as follows. 1. The acidity of control arrived at 0.99% after 16 hours of incubation during the incubation of Lactobacillus bulgaricus. Whereas that of CR starter medium reached 1.00% at 12 hours of incubation. Yeast extract, 1.12% at 12 hours, and Bios 2000 reached 0.97% at 10 hours respectively, Thus, Bios 2000 showed the fastest rate of acid production. 2. When the acidity of experiment medium peaked on optimum levels. pH of control was 4.03 in 16 hours of incubation during the incubation of Lactobacillus bulgaricus. Whereas that of Bios 2000 reached 4.10 of Yeast extract reached 3.97 at 12 hours, and of CR starter medium reached 4.05 at 12 hours. 3. Lactic acid bacterial counts were $3.1{\times}10^{10}/ml$ after 16 hours of incubation during the incubation of lactobacillus bulgaricus, Whereas those of Bios 2000 reached $2.1{\times}10^{10}/ml$ at 10 hours, with the fastest stimulation of growth, The counts in CR starter medium were at $2.9{\times}10^{10}/ml$ at 12 hours, and Yeast extract were $3.8{\times}10^{10}/ml$ at 12 hours. 4. The acidity of control, CR starter medium, and Yeast extract reached 0.92% at 44 hours, and 0.96% at 32 hours, and 0.90% at 32 hours respectively, Also, that of Bios 2,000 reached 0.97% at 32 hours, which exhibited the highest, among the treatments. 5. The pH of control was 4.27 at 44 hours. that of CR starter medium was 4.33 at 40 hours and that of Yeast extract was 4.25 at 32 hours during the incubation in Streptococcus thermophilus. Besides, pH of Bios 2000 is lowest as 4.18 at 32 hours. 6. Lactic acid bacterial counts in control, CR starter medium, and Yeast extract during the incubation of Streptococcus thermophilus were $9.8{\times}10^{9}/ml$ at 44 hours,$9.5{\times}10^{8}/ml$ at 40 hours, and $9.6{\times}10^{8}/ml$ at 32 hours. And, the highest number was $2.0{\times}10^{9}/ml$ for Bios 2000 at 32 hours. 7. The acidity of control during the incubation of Lactobacillus casei reached 0.92% at 40 hours, and those of CR starter medium and Yeast extract were 0.95% at 40 hours, and 1.01% at 36 hours respectively. Also, Bios 2000 had the highest acidity as 0.94% at 32 hours. 8. The pH of control, CR starter medium and Yeast extract during the incubation Lactobacillus casei was 4.27 at 40 hours. 4.21 at 40 hours, and 4.15 at 36 hours respectively. Also, Bios 2000 showed the lowest pH, as 4.23, at 32 hours. 9. Lactic acid bacterial counts in control, CR starter medium and Yeast extract during the incubation of Lactobacillus casei were $9.4{\times}10^{7}/ml$ at 40 hours, $1.1{\times}10^{8}/ml$ at 40 hours, and $5.0{\times}10^{8}/ml$ at 36 hours respectively. And, the progress of 32 hours showed the highest number of lactic acid bacteria as$6.4{\times}10^{8}/ml$ in Bios 2000.
산효유제품(酸酵乳製品) 제조시(製造時) 유산균(乳酸菌) Starter의 산효성(酸酵性)을 촉진(促進)하기 위한 기초연구(基礎硏究)로서 Bulk medium에 Bios 2000, CR starter medium 및 Yeast extract를 각각(各各) 1.5%씩첨가(添加)하고 Lac. bulgaricus, Str. thermophilus 및 Lac. casei를 접종(接種) 배양(培養)하고 산도(酸度), pH 및 유산균수(乳酸菌數)의 변화(變化)를 조사(調査)한 결과(結果)는 다음과 같다. 1. Lactobacillus bulgaricus의 배양(培養)중 산(酸) 생성도(生成度)는 Control구(區)는 배양(培養) 16시간(時間)에 0.99%에 이르렀는데 비하여, CR starter mediurn 첨가구(添加區)는 배양(培養) 12시간(時間)에 1.0%이었고, Yeast extract 첨가구(添加區)는 배양(培養) 12시간(時間)에 1.12% 이였으며, Bios 200첨가구(添加區)는 배양(培養) 10시간(時間)만에 0.97%로써 가장 빠른 산생성도(酸生成度)를 보였다. 2. Lac bulgaricus의 배양(培養)중 pH의 변화(變化)는 Control구(區)는 배양(培養) 16시간(時間)에 4.03이였는데 반하여 Bios 2000 첨가구(添加區)는 배양(培養) 10시간(時間)에 4.10에 이르렀다. 또한, Yeast extract 첨가구(添加區)는 배양(培養) 12시간(時間)에 3.97, CR starter medium 첨가구(添加區)는 배양(培養) 12시간(時間)에 4.05를 나타내었다. 3. Lac. bulgaricus의 배양(培養)중 유산균수(乳酸菌數) 변화(變化)는 Control구(區)가 배양(培養) 16시간(時間)에 $3.1{\times}10^{10}/ml$이 되었는데 반하여 Bios 2000 첨가구(添加區)는 10시간(時間)에 $2.1{\times}10^{10}/ml$에 이르러 가장 빠른 생육(生育) 촉진현상(促進現狀)을 보였다. 한펀, CR starter medium 첨가구(添加區)는 12시간(時間)에 $2.9{\times}10^{10}/ml$, Yeast extract 첨가구(添加區)는 12시간(時間)에 $3.8{\times}10^{10}/ml$를 나타내었다. 4. Streptococcus thermophilus의 배양(培養)중 Acidlty 변화(變化)는 Control구(區)가 44시간(時間)만에 0.92%에 이르렀으며, CR starter medium 첨가구(添加區)는 40시간(時間)에 0.96%, Yeast extract 첨가구(添加區)는 32시간(時間)에 0.90% 이었다. 한편, Bios 2000 첨가구(添加區)는 32시간(時間)에 0.97%로 가장 높게 나타났다. 5. Str. thermophilus 배양(培養)중 pH 변화(變化)는 Control구(區)가 44시간(時間)에 4.27 이고, CR starter medium 첨가구(添加區)는 40시간(時間)에 4.33, Yeast extract 첨가구(添加區)는 32시간(時間)에 4.25이었다. 한편, Bios 2000 첨가구(添加區)는 32시간(時間)에 4.18로 가장 높게 나타났다. 6. Str. thermophilus의 배양(培養)중 유산균수(乳酸菌數) 변화(變化)는 Control구(區)가 44시간(時間)에 $9.8{\times}10^{9}/ml$이고, CR starter medium 첨가구(添加區)는 40시간(時間)에 $9.5{\times}10^{8}/ml$, Yeast extract 첨가구(添加區)는 32시간(時間)에 $9.6{\times}10^{8}/ml$이었다. 한편, Bios 2000 첨가구(添加區)는 32시간(時間)에 $2.0{\times}10^{9}/ml$로 가장 높게 나타났다. 7. Lactobacillus casei 균종(菌種)의 배양(培養) 중의 Acidity 변화(變化)는 Control구(區)가 40시간(時間)에 0.92%에 이르렀으며, CR starter medium 첨가구(添加區)는 40시간(時間)에 0.95%, Yeast extract 첨가구(添加區)는 36시간(時間)에 1.01%이었다. 한편, Bios 2000 첨가구(添加區)는 32시간(時間)에 0.94%로 가장 높게 나타났다. 8. Lac. casei 균종(菌種)의 배양(培養)중 pH 변화(變化)는 Control구(區)가 40시간(時間)에 4.27이고, CR starter medium 첨가구(添加區)는 40시간(時間)에 4.21, Yeast extract 첨가구(添加區)는 36시간(時間)에 4.15이었다. 한편, Bios 2000 첨가구(添加區)는 32시간(時間)에 4.23으로 가장 높게 나타났다. 9. Lac. casei균종(菌種)의 배양(培養)중 유산균수(乳酸菌數) 변화(變化)는 Control구(區)가 40시간(時間)에 $9.4{\times}10^{7}/ml$이고, CR starter medium 첨가구(添加區)는 40시간(時間)에 $1.1{\times}10^{8}/ml$, Yeast extract 첨가구(添加區)는 36시간(時間)에 $5.0{\times}10^{8}/ml$이었다. 한편, Bios 2000 첨가구(添加區)는 32시간(時間)에 $6.4{\times}10^{8}/ml$로 가장 높게 나타났다.