구기자, 구기엽 및 지골피를 첨가한 요구르트의 발효 특성

This experiment was carried out to examine the fermentation properties of yogurt with Lycii fructus, Lycii folium and Lycii cortex powder, and extract additives at concentrations of 0.5, 1.0, 2.0, 4.0, and 6.0%. Lactic acid bacteria was used in a mixed starter culture of Streptococcus salivarius ssp. thermophilus(ST36) and Lactobacillus delbrueckii ssp. bulgaricus(LB12). When the boxthorn was added with extract types, the changes of pH, acidity and lactic acid bacteria counts of yogurt during the fermenation of 3 hours were pH 5.64, titratable acidity 0.85%, 5.80xl0$\^$6/cfu/ml of viable cell counts for control yogurt, whereas those were pH 4.10∼5.06, titratable acidity 0.98∼1.27%, 1.80∼9.60x10$\^$7/ cfu/ml of viable cell counts for Lycii fructus extract yogurt. The lactose hydrolysis ratio was better for 1.0% Lycii fructus extract yogurt(42.00%) and 1.0% Lycii folium extract yogurt(41.46%) than for control yogurt(28.40%). Also, content of lactic acid of 1.0% Lycii fructus(11.9 times) and 1.0% Lycii folium extract yogurt(10.6 times) produced more than control yogurt(7.3 times). The viscosity of yogurt was better for boxthorn extract yogurt(1,027∼1,382 cps) than for control yogurt(975cps). The sensory scores of color, taste and overall acceptability of yogurt with 0.5, and 1.0% Lycii fructus extract additive were better than other groups. The yogurts made with increased Lycii fructus extract concentration(0.5∼6.0%), showed the increase of lactic acid, titratable acidity, number of lactic acid bacteria, viscosity and lactose hydrolysis rate compared to the treatments of 0.5, 1.0, 2.0, and 4.0% Lycii folium and Lycii cortex extract and powder yogurt. We gained excellent results from the yogurt to which Lycii fructus extract was added with 0.51.0% concentration. 구기자, 구기엽 및 지골피에는 rutin, betaine, $\beta$-sitosterol, kukoamin A, sugiol등의 기능성 성분이 다량 함유되어 있고, 이를 이용한 다양한 구기자 가공제품 개발이 추진되고 있는 바, 된 연구에서는 생구기자, 분말형태의 구기자, 구기엽 및 지골피와 extract 형태로 구분하여 유산균을 이용한 발효유에 첨가하고 그 발효특성을 구명하였다. yogurt 제조시 0.5∼6.0% 첨가하여 15시간 배양하면서 pH, 적정산도. 유산균수, 유당함량, 유기산함량, 점도 및 관능검사를 실시한 결과는 다음과 같다. 1. 구기자, 구기엽, 지골피의 각 첨가구는 첨가량이 증가함에 따라 pH, 적정산도와 유산균수의 증식을 촉진하였고, 생구기자와 분말형태의 첨가보다는 extract 형태의 첨가물이 유산균의 증식을 촉진하였다. 또한 extract 형태로 첨가시 배 양 3시간에 control구가 pH 5.64, 적정산도 0.85%, 유산균수 5.80${\times}$$10^{6}$ cfu/mL인데 비하여, 구기자 extract는 pH 4.10∼5.06, 적정산도 0.98∼l.27%, 유산균수 1.80∼9.60x$10^{7}$ cfu/mL 로서 현저한 pH 저하와 적정산도의 증가 그리고 가장 많은 유산균수를 나타내었다. 2. 각 첨가물을 이용하여 제조한 yogurt의 유당함량과 유기산조성을 HPLC로 분석한 결과, 첨가량이 높아짐에 따