Abstract
This experiment was carried out to investigate the effect of Maesil extract on the acid production and growth of yoghurt starter in the skim milk medium. The Maesil extract was added to skim milk medium fur 1% to 9% and the medium was fermented by single or mixed culture of 4 types of lactic acid bacteria(Streptococcus thermophilus, Lactobacillus acidophilus, Lactobacillus, bulgaricus, Lactobacillus casei). The chemical composition of Maesil, the changes in acid production (titratable acidity, pH) and number of viable cells of the medium during lactic fermentation in skim milk added with Maesil extract, and the keeping quality of curd yoghurts containing Maesil extract have determined. The composition of Maesil were 0.4% crude ash, 4.1% dietary fiber, 4.66%l citric acid, 0.264% total sugars and 405.34mg% vitamin C. The addition of Maesil extract stimulated the acid production and propagation of the lactic acid bacteria. Among the treatments tested, the addition of 3% Maesil extract with the mixed culture of Streptococcus thermophilus, Lactobacillus acidophilus and Lactobacillus casei produced the highest amount of acid(1.23%) and showed the highest number of viable cell counts(3.6$\times$10$^{11}$ cfu/mL). When the curd yoghurts containing 3% Maesil extract with the mixed culture of the lactic acid bacteria were kept at 4$^{\circ}C$ and 2$0^{\circ}C$ for 30 days, it was showed that the changes of titratable acidity, pH and number of viable cell counts of the lactic acid bacteria were not significantly different during storage. Therefore the keeping quality of the curd yoghurts adding 3% Maesil extract showed relatively good at the shelf-life.
Skim milk에 매실 착즙액을 수준별로 첨가하고 4종(Streptococcus thermophilus, Lactobacillus acidophilus, Lactobacillus bulgaricus, Lactobacillus casei)의 젖산균을 단독균주 또는 혼합균주로 접종하여 매실 착즙액의 첨가가 젖산균의 산생성 및 생육에 미치는 영향과 저장성을 조사하였고, 매실 착즙액으로 사용한 매실의 일반 성분을 분석하였다. 매실의 일반 성분은 조회분 0.4%, 식이섬유 4.1%, 구연산 4.66%, 총당 0.264%, vitamin C 405.34mg%이었고, 매실 착즙액의 첨가는 젖산균의 증식을 촉진시켰으며 산생성도 증가하였다. 실험구 중 Str. thermophilus, Lac. acidophilus와 Lac. casei의 혼합균주에 3% 매실 착즙액을 첨가한 실험구가 가장 많은 양의 젖산(1023%)을 생성하였고, 가장 높은 생성균수(3.6$\times$$10^{11}$ cfu/mL)를 나타내었다. 매실 착즙액 3% 첨가 호상 요구르트를 대조구와 함께 4$^{\circ}C$와 2$0^{\circ}C$에서 30일 동안 저장한 결과, 세 개의 혼합균주(Str. thermophilus, Lac. acidophilus)를 사용한 호상 요구르트가 4$^{\circ}C$에서 pH는 4.25, 생균수는 4.1$\times$$10^{9}$ cfu/mL 이었고, 2$0^{\circ}C$에서 pH는 3.76, 생균수는 8.7$\times$$10^{8}$ cfu/mL으로 대조구인 매실 무첨가 호상 요구르트에 비하여 높은 저장성을 나타내었다. 이상의 결과로 보아 매실 착즙액을 첨가한 호상 요구르트의 제조가 가능할 것으로 사료된다.
