• Journal of the Korean Society of Food Science and Nutrition
• /
• v.21 no.1
• /
• pp.60-63
• /
• 1992

Individual starter culture were inoculated into liquid medium and incubated at $40^{\circ}C$ for 16 hours. Whole cell were obtained and evaluated for ${\beta}-galactosidase$ activity using orthonitrophenyl-${\beta}-D-galactopyranoside$ (ONPG) as substrate. S. thermophilus had more ${\beta}-galactosidase$ activity than other Lactobacilli did. To study the effect of storage temprature on enzyme activity of yoghurt, some samples of cultured yoghurt were stored under refrigeration $(4^{\circ}C)$, and the others under room temperature $(23^{\circ}C)$. At $4^{\circ}C$, yoghurt had ${\beta}-galactosidase$ activity and many viable bacteria in 1 month. After 20 days, yoghurt had maximum ${\beta}-galactosidase$ activity. At $23^{\circ}C$, yoghurt had ${\beta}-galactosidase$ activity by 5 days. As this experiment shown ${\beta}-galactosidase$ activity was ascribed to viable bacteria, especially S. thermophillus. Commercial yoghurt had lower ${\beta}-galactosidase$ activity. There were considerable variations with regard to the lactose hydrolyzing capabilities of commercial yoghurt samples.

• Korean Journal of Agricultural Science
• /
• v.23 no.2
• /
• pp.219-226
• /
• 1996

Liquid yoghurts were made with ginseng extract, white ginseng powder and tail ginseng powder, which have pharmacological effects and are palatable by Korean. The acidity, number of lactic acid bacteria and viscosity of yoghurts were examined and taste, flavor and characteristics of preservation of yoghurts were also tested. The results obtained were summarized as follows; l. The acidity of yoghurt was high for ginseng yoghurts, especially tail ginseng yoghurt(1.15%) was higher than that of control yoghurt(0.76%). 2. The number of lactic acid bacteria in yoghurt was higher for ginseng yoghurt than that of control yoghurt($1.5{\times}10^8/m{\ell}$), especially tail ginseng yoghurt($4.3{\times}10^8/m{\ell}$) showed the highest number of lactic acid bacteria. 3. The viscosity of yoghurt was high for ginseng yoghurt, especially white ginseng powder yoghurt was higher than that of control. 4. The score of yoghurts for tastes, flavor and overall acceptability were higher for tail ginseng yoghurt than those of control yoghurt. 5. When yoghurts were stored at $5^{\circ}C$ for 10 days, the pH, acidity, number of lactic acid bacteria of all yoghurt were not changed significantly.

• The Korean Journal of Food And Nutrition
• /
• v.7 no.2
• /
• pp.151-158
• /
• 1994

This study was carried out to clear up the cause of low-acid producing phenomenon occurred In non-fat dry milk during liquid-yoghurt fermentation by Lactobacillus case, and to present its improving methods. All samples of non-fat dry milks which were low in TCA-soluble peptides showed low-acid production, but those high in TCA-soluble peptides showed high-acid production. The addition of trypsin-hydrolysate of Na-caseinate to non-fat dry milk showed some improving effect on acid production but that of papain-hydrolysate did not show any improving effect and that of bacterical neutral protease-hydrolysate showed some inhibitory effect. The improving effects on growth and acid production of lactic acid bacteria were more prominent when the trypsin-hydrolysate of Na-caseinate was added. to such fermenting system in which the levels of TCA-soluble peptides and the proteolytic ability of starter bacteria were abnormally low. The liquid-yoghurt made with non-hydrolysed Na-caseinate and defective non-fat dry milk showed precipitate occurrence but that with trypsin-hydrolysate of Na-caseinate and defective non-fat dry milk did not make any precipitate during storage as with normal non-fat dry milk.

• Korean Journal of Food Science and Technology
• /
• v.21 no.6
• /
• pp.795-799
• /
• 1989

This study was carried out to hydrolyze lactose in commercial milk by ${\beta}-galactosidase$ from Kluyveromyces fragilis and to compare some physicochemical properties of yoghurts made from control and lactase-treated commercial milks. Quantitative analysis of sugars was performed by gas liquid chromatograph (GLC) on trimethylsilyl (TMS) derivatives. In commercial milk, 94.6% of lactose was hydrolyzed after 2 hours incubation at $40^{\circ}C$ with 6.0 units/ml of ${\beta}-galactosidase$. pH, titratable acidity and viable cell number of yoghurt made from lactase-hydrolyzed (LH) commercial milk were 4.1, 1.04% and $6.5{\times}10^8/ml$ of Str. thermophilus, $8.9{\times}10^8/ml$ of L. bulgaricus after 8 hours incubation at $40^{\circ}C$, respectively, The total contents of amino acid were 2.63% in control and 2.19%. in LH yoghurt. The total contents of free amino acid were 26.95 mg% in control and 17.55mg% in LH yoghurt. Analysis of free fatty acids resulted in that the contents of short chain fatty acids in LH yoghurt were a little higher than those in control. Both in control and LH yoghurt, the palmitic acid content was highest and that was followed by oleic and myristic acid.

• The Korean Journal of Food And Nutrition
• /
• v.17 no.2
• /
• pp.128-137
• /
• 2004

For the purpose of making a functional drinkable yoghurt, new types of drinkable yoghurts were prepared from skim milk added with 0.25％ chlorella extract powder and 2.5-10.0％ chlorella extract liquid. Quality characteristics of the drinkable yoghurts were evaluated in terms of quality-keeping property(pH, titratable acidity, number of viable cells) and sensory properties. When the drinkable yoghurts containing chlorella extract(0.25％ chlorella powder and 2.5-10.0％ chlorella extract liquid) were kept at 4$^{\circ}C$ and 20$^{\circ}C$ for 15days, the pH(pH 4.13-4.27), titratable acidity(0.66-0.75％) and number of viable cell counts of the lactic acid(8.42-8.89 log CFU/$m\ell$) were not significantly changed for all drinkable yoghurts during the storage at 4$^{\circ}C$ for 15days, but the pH(pH 3.53-3.56) and titratable acidity(1.30-1.37％) and number of viable cell counts(9.15-9.45 log CFU/$m\ell$) were markedly changed for the storage at 20$^{\circ}C$ for 15days. Therefor the keeping quality of the drinkable yoghurts with addition of chlorella extract was relatively good at 4$^{\circ}C$ for 15days. The results of sensory evaluation of the drinkable yoghurts containing chlorella extract indicated that color, chlorella taste, aftertaste and overall acceptability of the drinkable yoghurt with no addition of chlorella extract showed higher preference than others. And also sensory scores of the yoghurt added with 20％ oligosaccharide were significantly higher than other groups in aftertaste and overall acceptability.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.22 no.6
• /
• pp.815-822
• /
• 1993

This experiment was carried out to determine the separation condition of 1-dimethylaminonaphthalene-5-sulfony(Dansyl) derivatives of amino acids by reverse-phase high performance liquid chromatography with Nova-Pak C18 column. Determined solvent system was solvent A(200mA phosphate buffer pH 6.8 15%, acetonitrile 11%, water 74%) and solvent B(acetonitrile 65%, methanol 28%, water 7%). Linear gradient of solvent B was applied from 12% to 80% for 50min. Complete separation of 20 amino acids including asparagine and glutamine which constitute protein was achieved within 50min. As the detection limit was the range of picomole, the resolution power was excellent. Reproducibility of the retention time was less than mean $\pm$0.05min. According to the above optimum chromatographic conditions, the amino acid composition of some food and human blood was examined. The most affluent amino acid was alanine in human blood, aspartic acid and glutamic acid in soy sauce, alanine and threonine in soy milk and proline in milk and yoghurt.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.28 no.2
• /
• pp.129-138
• /
• 2008

Demand for alternatives to petroleum is increasing the production of biofuels from food crops such as corn, soybeans, sorghum and sugarcane, etc. At least for the next 5 years, ethanol demand will be increased greatly in the United States and in the world. Presently, most ethanol produced in the United States is corn (Zea mays) ethanol. As a result, especially in the Americas and Southeast Asia, agricultural land is diverted to biofuel production. Even though biofuel industry has many advantage including national security, economical, energetical and sustainable impacts, it is driving grain prices up and creating considerable concern about the potential negative impacts on a wide range of food products that depend on gain : chicken, pork, beef, and dairy products such as milk, cheese, yoghurt, cream and ice cream. Feedstock crops are crops such as switchgrass(Panicum virgatum, L.), corn stover and grasses that can be used in industrial processes such as fermentation into alcohol fuels. Feedstock is no compete with food. Furthermore it is friendly environmental bioenergy crops. In Korea, with increasing demand for fossil fuels the exploration of alternative sources of liquid fuel is inevitable. I suggest Korea need to research and to develop actively on feedstock for biofuel production through this review.

• Microbiology and Biotechnology Letters
• /
• v.12 no.4
• /
• pp.285-291
• /
• 1984

In making liquid yoghurt, the influences of proteolytic ability of lactic acid bacteria on acid production and on protein stability were investigated. L. bulgaricus CH-2, L. helviticus IAM 1042 and L. jugurti 3048 showed a comparatively high proteolytic activity in milk, while L. casei YIT 9018 did not show any marked proteolysis. Starter organisms having high proteolytic ability showed more rapid growth and acid production than those having low ability in milk. The most active proteolysis occurred during logarithmic growth phase of yogurt organisms, and most of the proteolysis took place in the first 24-48 hrs of incubation. Highly proteolysed yogurts made by L. bulgaricus CH-2, L. jugurti 3048, L. helviticus IAM 1042, L. acidophilus L-54 and L. casei 3012 had low protein solubility at pH 3.5 and had much protein precipitates during storage of product, but those having little protein hydrolysates made by L. casei YIT 9018 or artificial acidification showed no precipitation during keeping.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.33 no.3
• /
• pp.593-597
• /
• 2004

This study was conducted to investigate the quality characteristics of liquid calcium acetate (LCAs) and solid calcium acetate (SCAs), Br-LCA, Pe-LCA and Ap-LCA as liquid form, Br-SCA, Pe-SCA and Ap-SCA as solid form. Calcium acetate was prepared by reacting of vinegars [brown rice (Br), persimmons (Pe) and apple (Ap)] and ash of black snail in order to obtain natural water soluble calcium resources. The pHs of the vinegars for preparing calcium acetate (CA) were the range of 2.34 ∼ 3.06, and the contents of the ash of black snail which reacted to 100 mL of the vinegars were 20.43∼23.50 g. The yields of solid CAs from 100 mL of the vinegars were 11.02∼13.01 g. The colors of liquid and solid CAs were light yellow in Ap-LCA and Ap-SCA, brown in Br-LCA and Br-SCA, dark brown in Pe-LCA and Pe-SCA. Calcium contents of Br-LCA, Pe-LCA and Ap-LCA were 3.02, 2.06 and 2.30% (w/v), and those of Br-SCA, Pe-SCA and Ap-SCA were 27.15, 16.31 and 19.48% (w/w), respectively. The solubilities of the solid CAs were 36.82 ∼ 39.92% (w/v) in distilled water, 32.05 ∼ 39.04% (w/v) in Soju, 13.12 ∼ 18.65% (w/v) in thick soysauce, 38.35 ∼ 38.90% (w/v) in ionic beverage, 33.47 ∼ 35.58% (w/v) in yoghurt, while the solid CAs formed the curds in soymilk and milk. The sour and bitter taste of the CAs were lower, while the astringent taste, fishy flavor and savory taste were higher than those of standard CA.

• Culinary science and hospitality research
• /
• v.17 no.3
• /
• pp.236-258
• /
• 2011

This study investigates the intake and consumption behavior for milk and dairy products among middle school students in Gyeonggi Province. 'The result of the study is as follows. Only 37.4% of the subjects drink milk everyday, and 56.7% of them drink one cup of milk a day. 69.2% of them usually drink plain milk whereas most of them prefer flavored milk rather than plain milk. Reasons to drink milk are 'want to be tall' and 'good to drink' while the reasons not to drink milk are 'its bad taste' and 'prefer other beverages.' 36.7% take dairy products 3~4 times per week. Male students prefer ice-cream among dairy products while female students prefer liquid-type yoghurt. Most of the students consume dairy products for 'good taste,' 'good to eat,' 'want to be tall' in order. Those who don't consume dairy products say the major reason to dislike dairy products is 'their families do not drink dairy products at home'. As for the health benefit of dairy products, 79.9% of the subjects think that the products are of no effect. When they buy milk and dairy products, the most important standard of selection is 'shelf-life' for milk and 'favorite dairy products' for dairy products. Most of the students think that 'better taste and qualify' and 'better sanitation' will increase their consumption of milk and dairy products.