통보리가루 첨가 요구르트의 저장 중 품질 특성

이미자,김양길,김경호,이나영 한국산업식품공학회 2015 산업 식품공학 Vol.19 No.1

Quality characteristics were evaluated for whole barley yogurt prepared with lactic acid bacteria combination such as Lactobacillus acidophilus, Lactobacillus delbrueckii subsp. Bulgaricus, and Streptococcus thermophilussei (1:1:1) with the addition of whole barley flour at 3%. The barley yogurt had lower pH, higher titratable acidity, and higher sugar content than control yogurt. The viable cell number of the barley yogurt was lower than the control yogurt. However, the viscosity and antioxidant activity of the barley yogurt were higher than those of the control yogurt. In up to 12 d of storage at 4oC, pH decreased while titratable acidity increased in both control yogurt and barley yogurt. The sugar content and brightness increased slightly. The viable cell number of the barley yogurt decreased during storage. However, the viable cell number of the barley yogurt met the standard suggested by the KFDA. Although the viscosity of the barley yogurt decreased, it corresponded to the required viscosity of a curd yogurt. Antioxidant activity slightly increased up to 9 d and then decreased, but the decrease of antioxidant activity was smaller in barley yogurt than in the control yogurt. During storage, there was no curd separation, change in scent, etc. Thus the storage quality of barley yogurt was relatively good.

통보리가루 첨가 요구르트의 저장 중 품질 특성

이미자 ( Mi Ja Lee ),김양길 ( Yang Kil Kim ),김경호 ( Kyung Ho Kim ),이나영 ( Na Young Lee ) 한국산업식품공학회 2015 산업 식품공학 Vol.19 No.1

본 연구에서는 3%의 통보리가루를 첨가하여 Lactobacillus acidophilus, Lactobacillus delbrueckii subsp. Bulgaricus, Streptococcus thermophilussei (1:1:1) 등 3종의 혼합 균주를 이용하여 보릿가루를 첨가한 요구르트를 제조하고 4℃ 의 저장 온도에서 저장하면서 3일 간격으로 12일 동안 품질 분석을 하여 요구르트의 저장성을 조사하였다. 보릿가루를 첨가한 요구르트는 대조군에 비하여 pH는 낮고 산도와 당도는 높았으며 유산균 수는 약간 적었으나 점도와 항산화 활성은 높았다. 저장 기간이 경과함에 따라 대조군과 보릿가루 첨가군 모두 pH는 감소하였고, 보릿가루 첨가군에서 산도는 증가 하였다. 당도는 저장기간이 경과함에 따라 미미하게 증가하는 경향을 보였고, 밝기는 대조군과 보릿가루 첨가군에서 모두 증가하였다. 대조군에서 유산균수는 저장 12일차에 급격히 감소하였으나 보릿가루 첨가군은 본 실험의 저장기간 동안 축산물의 가공기준 및 성분규격의 유산균수에 모두 부합하였다. 점도는 저장기간에 따라 감소하였지만 보릿가루 첨가군은 저장기간이 길어짐에도 호상 요구르트의 점도 조건에 부합하는 것으로 나타났다. 항산화 활성은 전체 저장기간 동안 보릿가루 첨가군이 대조군보다 높았으며, 대조군은 9일까지 증가하다가 12일차에서는 감소 하였고 보릿가루 첨가군은 12일까지 지속적인 감소를 보였다. 12일간의 저장기간 동안 보릿가루 첨가 요구르트의 외관과 향 등에서 큰 변이가 없어 저장성은 우수하였다. Quality characteristics were evaluated for whole barley yogurt prepared with lactic acid bacteria combination such as Lactobacillus acidophilus, Lactobacillus delbrueckii subsp. Bulgaricus, and Streptococcus thermophilussei (1:1:1) with the addition of whole barley flour at 3%. The barley yogurt had lower pH, higher titratable acidity, and higher sugar content than control yogurt. The viable cell number of the barley yogurt was lower than the control yogurt. However, the viscosity and antioxidant activity of the barley yogurt were higher than those of the control yogurt. In up to 12 d of storage at 4oC, pH decreased while titratable acidity increased in both control yogurt and barley yogurt. The sugar content and brightness increased slightly. The viable cell number of the barley yogurt decreased during storage. However, the viable cell number of the barley yogurt met the standard suggested by the KFDA. Although the viscosity of the barley yogurt decreased, it corresponded to the required viscosity of a curd yogurt. Antioxidant activity slightly increased up to 9 d and then decreased, but the decrease of antioxidant activity was smaller in barley yogurt than in the control yogurt. During storage, there was no curd separation, change in scent, etc. Thus the storage quality of barley yogurt was relatively good.

Physicochemical and Microbiological Properties of Yogurt-cheese Manufactured with Ultrafiltrated Cow's Milk and Soy Milk Blends

이나경,목보람,RENDAKANKANAMGE CHATURIKA JEEWANTHI,윤여창,백현동 한국축산식품학회 2015 한국축산식품학회지 Vol.35 No.2

The objective of this study was to develop yogurt-cheese using cow’s milk, ultrafiltrated cow’s milk, and soy milk. The addition of soy milk and ultrafiltrated milk increased the amount of protein in the yogurt-cheese. Yogurt-cheeses were made using cheese base using 10% and 20% soy milk with raw and ultrafiltrated cow’s milk, and stored at 4°C during 2 wk. The yield of yogurt-cheeses made with added soy milk was decreased and the cutting point was delayed compared to yogurt-cheese made without soy milk. Yogurt-cheese made using ultrafiltrated cow’s milk showed the highest yield. However, yogurt-cheese made with added soy milk had higher protein content and titratable acidity than yogurt-cheese made using raw and ultrafiltrated cow’s milk. Fat and lactose contents in the yogurt-cheese made with added soy milk were lower. Yogurt-cheeses made with added soy milk contained several soy protein bands corresponding to the sizes of α2-, β-, and κ-casein band. Yogurt-cheese made with added soy milk had similar elasticity to yogurt-cheese made without soy milk but had lower cohesiveness. There was no significant difference in the number of lactic acid bacteria in the different cheeses, as all had over 8.0 Log CFU/g. Considering these data and the fact that proteins and fats of vegetable origin with high biological value were observed as well as unsaturated fats, yogurt-cheese made with added soy milk can be considered to be a functional food.

박테리오신 생성 Pediococcus acidilactici 를 적용한 요거트 특성 및 항균성 연구

현인경 ( In Kyung Hyun ),김민영 ( Min Young Kim ),김서연 ( Seo-yeon Kim ),이지수 ( Jee-su Lee ),최아랑 ( Ah-rang Choi ),강석성 ( Seok-seong Kang ) 한국낙농식품응용생물학회(구 한국유가공학회) 2020 Journal of Dairy Science and Biotechnology (JMSB) Vol.38 No.3

본 연구에서는 박테리오신을 생성하는 P. acidilactici를 적용한 기능성 요거트를 제조하여 항균활성과 프로바이오틱스로서의 품질을 평가하였다. Yogurt starter로는 시판되는 요거트에서 분리한 혼합 균주 3종(S. thermophilus, Lb. bulgaricus, Lb. rhamnosus GG)을 사용하였으며, 혼합 균주와 P. acidilactici HW01, P. acidilactici JM01, P. acidilactici K10을 각각 혼합 접종하여 각각의 요거트를 제조한 다음 유산균의 생균수, pH, brix를 측정한 결과, 유산균의 생균수는 모두 8.0 Log CFU/mL 이상의 생균수가 검출되어 유산균 발효유로서 기준에 적합하였다. 또한 pH와 brix를 측정한 결과, 발효 후 시간이 지남에 따라 모두 감소하였다. 우유나 유제품의 오염에 있어서 유의해야 할 병원성 균인 L. monocytogenes를 통해 병원성 저해능을 측정하였으며 L. monocytogenes가 발효 후 3일째부터 모두 저해되는 것이 확인되었다. 본 연구 결과를 통해 박테리오신 생성 균주인 P. acidilactici HW01, P. acidilactici JM01, P. acidilactici K10이 발효유제품 제조에 있어서 요거트 제품의 변화 없이 프로바이오틱 효과를 지닌 균주로 기대되며, 식품안정성 및 새로운 프로바이오틱스 유제품 개발에 도움을 줄 것이라 예상된다. 그리고 L. monocytogenes 외의 다른 병원성 균의 저해효과에 대한 연구 및 요거트의 저장온도에 따른 병원성 저해효과 차이에 대한 연구도 기대된다. 따라서 박테리오신 생성 균주를 활용한 기능성 식품을 실제 식품산업에 적용한다면 안전성 및 신제품 개발에 대한 연구가 더 이루어져야 될 것으로 보인다. Physical and sensory characteristics of commercial yogurts are important aspects for consumer acceptability. In addition, beneficial functions of commercial yogurts are also emphasized for the probiotic dairy products. The aim of this study was to investigate the functional properties of yogurts with the combination of bacteriocin-producing Pediococcus acidilactici. Yogurts fermented with commercial starter culture (control yogurt) and control yogurt together with P. acidilactici HW01 (yogurt+HW01), P. acidilactici JM01 (yogurt+JM01), or P. acidilactici K10 (yogurt+K10) were prepared. During 28 days after fermentation, the viability of lactic acid bacteria, pH, and brix, in the yogurt samples were assessed with standard methods. Moreover, to investigate the antilisterial activity of the yogurt samples, Listeria monocytogenes was simultaneously inoculated when the yogurts were prepared with lactic acid bacteria, and the viability of L. monocytogenes was determined. Although yogurt+K10 did not completely remove L. monocytogenes, control yogurt, yogurt+HW01, and yogurt+JM01 eradicated L. monocytogenes at day 2 after fermentation. However, yogurt+K10 also removed L. monocytogenes at day 3 after fermentation. Taken together, these findings suggest that the combination of yogurt with P. acidilactici does not affect its quality and they may consequently aid in the development of new probiotic yogurt.

Physicochemical and Microbiological Properties of Yogurt-cheese Manufactured with Ultrafiltrated Cow's Milk and Soy Milk Blends

Lee, Na-Kyoung,Mok, Bo Ram,Jeewanthi, Renda Kankanamge Chaturika,Yoon, Yoh Chang,Paik, Hyun-Dong Korean Society for Food Science of Animal Resource 2015 한국축산식품학회지 Vol.35 No.2

The objective of this study was to develop yogurt-cheese using cow’s milk, ultrafiltrated cow’s milk, and soy milk. The addition of soy milk and ultrafiltrated milk increased the amount of protein in the yogurt-cheese. Yogurt-cheeses were made using cheese base using 10% and 20% soy milk with raw and ultrafiltrated cow’s milk, and stored at 4°C during 2 wk. The yield of yogurt-cheeses made with added soy milk was decreased and the cutting point was delayed compared to yogurt-cheese made without soy milk. Yogurt-cheese made using ultrafiltrated cow’s milk showed the highest yield. However, yogurt-cheese made with added soy milk had higher protein content and titratable acidity than yogurt-cheese made using raw and ultrafiltrated cow’s milk. Fat and lactose contents in the yogurt-cheese made with added soy milk were lower. Yogurt-cheeses made with added soy milk contained several soy protein bands corresponding to the sizes of α₂-, β-, and κ-casein band. Yogurt-cheese made with added soy milk had similar elasticity to yogurt-cheese made without soy milk but had lower cohesiveness. There was no significant difference in the number of lactic acid bacteria in the different cheeses, as all had over 8.0 Log CFU/g. Considering these data and the fact that proteins and fats of vegetable origin with high biological value were observed as well as unsaturated fats, yogurt-cheese made with added soy milk can be considered to be a functional food.

Moringa extract enhances the fermentative, textural, and bioactive properties of yogurt

Zhang, Ting,Jeong, Chang Hee,Cheng, Wei Nee,Bae, Hyojin,Seo, Han Geuk,Petriello, Michael C.,Han, Sung Gu Elsevier 2019 FOOD SCIENCE AND TECHNOLOGY -ZURICH- Vol.101 No.-

<P><B>Abstract</B></P> <P>Yogurt is a fermented dairy food produced by lactic acid bacteria (LAB). <I>Moringa oleifera</I> is known for its bioactive properties. The aim of this study was to evaluate the effects of moringa on the fermentation, quality characteristics, and bioactive properties of yogurt. Yogurt was supplemented with 0–0.2% moringa extract (ME; hot water extract, 100 °C, 30 min) and fermented using mixed starter cultures (<I>Streptococcus thermophilus, Lactobacillus acidophilus,</I> and <I>Bifidobacterium longum</I>). Addition of ME to yogurt significantly accelerated the rate of fermentation by promoting growth of LAB. ME reduced syneresis up to 21% and enhanced the water-holding capacity by 17%. The viscosity of 0.2% ME yogurt was approximately 5-fold higher than control yogurt and radical-scavenging activity of ME yogurt increased up to 40% in a dose-dependent manner during the 21 days of cold storage. Sensory testing showed that the addition of 0.05% ME to yogurt did not negatively influence the overall acceptability of the product, compared to the control. The addition of ME to yogurt decreased the oxidative stress and increased the expression of antioxidant proteins in human colon cells. Thus, ME-fermented yogurt maintains the sensory acceptability and exerts positive health benefits because of increased LAB proliferation and enhanced antioxidant properties.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Addition of moringa extract (ME) to yogurt accelerated fermentation rate. </LI> <LI> ME reduced syneresis and enhanced the water-holding capacity of yogurt. </LI> <LI> Viscosity and radical-scavenging activity increased in ME yogurt over 21 days. </LI> <LI> ME increased the expression of antioxidant proteins in human intestinal cells. </LI> <LI> ME yogurt maintains sensory acceptability and possesses antioxidant effects. </LI> </UL> </P>

당류 및 안정제가 Frozen-Yogurt의 품질특성에 미치는 영향

박준홍,안성일,채창훈,주진우,김거유 강원대학교 동물자원공동연구소 2018 동물자원연구 Vol.29 No.3

This study was conducted to investigate the effects of sugars and stabilizers on the qualitative properties of frozen-yogurt. To prepare the yogurt mix, market milk was fermented using a commercial starter culture and sugars, trehalose and sucrose, and to prepare the ice cream mix, stabilizers, carboxy methyl cellulose (CMC) and guar gum, were used. The yogurt and ice cream preparations were mixed in a 1:1 (v/v) ratio to produce frozen-yogurt. Yogurt prepared using trehalose showed a significantly faster increase in pH, titratable acidity, and viable cell count than that prepared using sucrose (p<0.05). Ice cream prepared using guar gum showed a significantly higher viscosity and overrun than the CMC-stabilized preparation (p<0.05). Frozen-yogurt produced using the yogurt-trehalose mix and ice cream-CMC mix showed the highest hardness and lowest overrun. The melt-down rate of frozen-yogurt prepared with the yogurt-trehalose mix was significantly slow (p<0.05). However, there were no significant differences among the yogurt mixes in terms of changes in the viable cell count at 0, 7, 15, 30, and 45 days (p>0.05). In a sensory evaluation, most panels preferred the frozen-yogurt with sucrose over that with trehalose. However, it is expected that using trehalose with other sugar substitutions and guar gums in manufacture of frozen-yogurt have high potentiality than using sucrose and CMC, and it is considered that it could reignite the stagnant domestic milk processing industry.

시판용 요구르트와 Lactobacillus acidophilus 요구르트의 생화학적 활성의 비교

류재기 ( Jae Ki Ryu ),이형선 ( Hyeong Seon Lee ),구본경 ( Bon Kyung Koo ),김현경 ( Hyun Kyung Kim ) 대한임상검사과학회 2015 대한임상검사과학회지(KJCLS) Vol.47 No.2

Lactic acid-producing bacteria such as Lactobacillus spp. function to ferment carbohydrates and produce ATP. Such Lactobacillus spp. are used for the production of commercial yogurts. Lactobacillus spp. are beneficial to the intestinal tract, and Lactobacillus acidophilus-containing yogurts have received considerable attention because of their preventive effects against early-stage cancer of the large intestine. In this study, lactic acid-producing bacteria were cultured from three different groups: commercial solid yogurt (for eating), commercial liquid yogurt (for drinking), and Lactobacillus acidophilus-containing yogurt. We first determined the optimum culture conditions for Lactobacillus spp. and then analyzed turbidity and pH in order to compare the growth abilities and lactic acid-production capacities among the groups. Finally, high-performance liquid chromatography was used to measure the lactic acid content in the culture supernatants, and the antibacterial activities against Staphylococcus aureus and Escherichia coli were compared among the three groups. The optimum culture conditions for Lactobacillus spp. were MRS medium at 25oC, for 24 h. The highest turbidity was found in L. acidophilus-containing yogurt, followed by liquid yogurt and solid yogurt. Similarly, the highest lactic acid production ability was found in L. acidophilus-containing yogurt, followed by liquid yogurt and solid yogurt. Culture supernatants from the three groups did not show any antibacterial activity towards S. aureus; however, supernatants derived from L. acidophilus-containing yogurt resulted in a 1.8 mm inhibitory zone against E. coli in a paper disk diffusion test. These results revealed the high level of lactic acid-production capacity and antibacterial activity in L. acidophilus-containing yogurt.

구기자, 구기엽 및 지골피를 첨가한 요구르트의 발효 특성

조임식,배형철,남명수 한국축산식품학회 2003 한국축산식품학회지 Vol.23 No.3

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 따라 유당의 분해율도 높고 유기산의 대부분을 차지하는 lactic acid의 함량도 첨가비율에 따라 비례하여 증가하였다. Control구가 28.40%의 유당분해율을 나타낸 것에 비하여 extract 형태의 구기자와 구기엽 1% 첨가구에서 42.00%와 41.46%의 높은 유당분해율을 나타냈으며, 유기산 생성함량에서도 control구가 7.3배의 lactic acid가 생성된 것에 비하여 구기자와 구기엽 extract 1% 첨가구에서는 11.9배와 10.6배의 높은 유산을 생성하였다. 3. 발효후yogurt의 점도는control구에 비하여 생구기자와 extract 형태의 첨가구는 첨가량에 따라 점도가 증가한 것에 비하여 분말형태의 첨가구는 첨가량이 증가함에 따라 점도가 감소하였다. 발효 요구르트의 control구가 975 체인데 비하여 exoact형태의 첨가구는 1,027∼1,382 cp의 높은 점도를 나타내었다. 구기자, 구기엽, 지골피 분말을 첨가한 처리구는 760∼125 cp로서 매우 낮은 점도를 형성하였다. 4. 구기자, 구기엽, 지골피를 부위별로 첨가한 yogurt의 관능검사 결과, control구에 비하여 생구기자와 분말형태의 구기자, 구기엽, 지골피 첨가구는 모든 관능평가에서 낮은 점수를 얻었으나, extract 형태의 0.5∼l.0%내 구기자, 구기엽,지골피 첨가구는 향취, 맛, 입안에서의 느낌, 색과 기호도 모두 control과 유사한 결과를 나타내어 구기자 첨가 yogurt 제품으로서 이용가능성이 있을 것으로 생각된다. 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.

Kefir에서 분리한 Streptococcus thermophilus LFG를 이용한 우유 및 산양유 요구르트의 품질 특성

임영순,이시경,Lim, Young-Soon,Lee, Si-Kyung 한국축산식품학회 2013 한국축산식품학회지 Vol.33 No.6

Kefir제품으로부터 slime생성력이 우수한 Str. thermophilus LFG를 분리하여 이 유산균과 상업균주인 Str. thermophilus TH3 및 Str. thermophilus LFG와 L. delbrueckii subsp. bulgaricus LB12 혼합균주로 산양유 및 우유를 이용하여 발효유를 제조하고 제품특성을 조사하였다. 젖산 함량은 산양유 발효유(743.9-1043.8 mg/100 g)가 우유 발효유(441.6-709.9 mg/100 g)보다 높았다. 저장 중 발효유의 생균수는 Str. thermophilus LFG로 배양한 발효유에서 가장 높았다. 점도는 우유 및 산양유 발효유에서 Str. thermophilus LFG 균주를 사용한 발효유에서 가장 높았으며 Str. thermophilus TH3를 사용시에 가장 낮았다. 우유 및 산양유 발효유의 syneresis는 Str. thermophilus LFG를 이용한 발효유가 9.6-16.1%이었으나 Str. thermophilus TH3를 발효시킨 발효유는 28.2-31.8%이었다. 산양유의 향기성분으로 acetone, ethylbutanoate, ethyl-3-methyl butyrate, ethyl-2-butenoate, ethylhexanoate 등이 분리되었으며, 우유의 향기성분으로는 ethylbutanoate, acetone, 2-heptanone, acetoin 등이 분리되었다. 산양유 및 우유 발효유에서 acetic acid, butanoic acid, butanol, diethylcarbinol, acetone, diacetyl, decane, 2-methyl-3-pentanone, hexanal, 2-heptanone, acetoin, benzaldehyde, dimethyldisulfide, dimethyltrisulfide 등 14개의 성분이 검출되었다. 관능평가에서 Str. thermophilus LFG로 발효시킨 산양유 발효유가 우유 발효유보다 전반적인 기호도와 조직감에서 높은 평가를 받았다. 특히 혼합균주를 사용한 발효유에서 가장 높았으며 풍미특성도 향상 시키는 효과를 보였다. This study was carried out to investigate the characteristics of goat and cow milk yogurts containing high-exopolysaccharide fermented by Streptoccous thermophilus LFG isolated from kefir. The pH of cow milk yogurt was higher than that of goat milk yogurt. The contents of lactic acid was greater in goat milk yogurt (743.9-1043.8 mg/100 g) than in cow milk yogurt (441.6-709.9 mg/100 g). The numbers of survival lactic acid bacteria were the greatest in goat milk yogurt fermented by Str. thermophilus LFG. Viscosity was greater in cow and goat milk yogurts cultured by Str. thermophilus LFG than in yogurts by Str. thermophilus TH3. Syneresis of yogurt fermented by Str. thermophilus LFG was 9.6-16.1% and 28.2-31.8% in yogurt fermented by Str. thermophilus TH3 after 10 d storage at $4^{\circ}C$. Flavor compounds identified from goat milk were acetone, ethylbutanoate, ethyl-3-methylbutyrate, ethyl-2-butenoate and ethylhexanoate, and those from cow milk were ethylbutanoate, acetone, 2-heptanone and acetoin. Flavor compounds detected from goat milk and cow milk yogurts were acetic acid, butanoic acid, butanol, diethylcarbinol, acetone, diacetyl, decane, 2-methyl-3-pentanone, hexanal, 2-heptanone, acetoin, benzaldehyde, dimethyldisulfide, and dimethyltrisulfide. In sensory evaluation, overall preference and texture values were higher in goat milk yogurt fermented by Str. thermophilus LFG than in cow milk yogurts and the yogurt fermented by mixed culture resulted in the highest score.