• 산업기술연구
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• 제1권
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• pp.61-66
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• 1981

In order to use as a starter after drying, optimum growth conditions of Str. thermophilus and L. bulgaricus were investigated. The results were as follows. The growth of Str. thermophilus was reached at stationary phase after 12 hours incubation and L. bulgaricus was after 6 hours. Str. thermophilus was grown well, in the medium containing 10% of skim milk, 2% of sucrose, 0.1% of KCl and 0.015% (v./v.) of soy-sauce. In the case of L. bulgaricus, 10% of skim milk, 2% of glucose, 0.5% of bacto-peptone, 0.1% of $K_2HPO_4$ and 0.02% of pyridoxine was suitable for the maximum growth.

• 한국가축번식학회지
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• 제14권1호
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• pp.57-65
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• 1990

본 연구는 국립종축원과 경기도 남양주시의 개인 농장으로 부터 얻은 혈장과 유즙은 발정전 5일부터 시작 하여 2일 간격으호 30일간 채취하여 RIA와 CIA로 혈장, 전유 그리고 탈지유내의 progesterone을 측정 하여 발정주기중의 progesterone 농도 변화를 조사하였으며, 아울러 RIA와 대체할 수 있는 비방사성 면역 분석법인 CIA방법의 적용가능성을 조사하기 위하여 탈지유내 progesterone을 CIA와 RIA로 옹시에 측정하였던 바 다음과 같은 결과를 얻었다. 1. 혈장내 progesterone 수준은 발정전 8일까지 낮은 수준을 유지하다가 그후 급격히 증가하여 발정전 14일에 최고수준인 6.3ng/ml에 도달하였다. 그후 감소 하기 시작하여 발정전 16일에는 3.6ng/ml, 18일에는 1.5 ng/ml, 20일에는 2.2 ng/ml로서 최고수준을 나타냈다. 2. 임산우의 전유내 progesterone 농도는 발정일에 0.1 ng/ml에서 점차 증가하기 시작하여 발정후 10일 부터는 11ng/ml ~ 21ng/ml 까지의 높은 수준을 계속 유지하였다. 3 비임산우의 경우 전유내 progesterone농도는 발정일에 1.5 ng/ml 로서 낮은 수준을 나타냈으며 발정후 6일부터는 갑자기 증가하기 시작하며 발정후 16일까지 17.8~20.0 ng/ml까지의 높은 수준을 유지하다가 18일 이후부터는 1.4 ng/ml로서 낮은 수준을 유지하였다. 4. 탈지유내 progesterone수준은 임산우의 경우 발정개시때에 130-490pg/ml로서 낫은 수준을 유지하다가 발정 10일 이후에는 990-1650 pg/ml 까지의 높은 수준을 계속해서 유지했다. 5. 비임산부의 경우 탈지유내 progesterone 농도는 발정일에 160 pg/ml 로서 낮은 수준을 유지하다가발정후 8일부터 16일까지 1050-1300 pg/ml 까지 높은 수준을 오르내렸다 그후 탈지유내 progesterone수준을 240~450 pg/ml의 낮은 수준으로 나타났다. 6. 탈지유내 progesterone 농도를 CIA 와 RIA 방법으로 동시에 측정하여 상간관계플 조사하였던 바 좋은 상간관계(r=0.914)를 보였다.

• 한국축산식품학회:학술대회논문집
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• 한국축산식품학회 1998년도 추계학술발표회
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• pp.167-167
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• 1998

• 대한수의학회지
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• 제34권1호
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• pp.181-188
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• 1994

In 60 dairy cows with inactive ovaries, follicular cyst, luteal cyst, persistent corpus luteum and silent heat as diagnosed by rectal palpation, and those that had not resumed ovarian cycles until 60 days postpartum, progesterone concentrations for differential diagnosis of reproductive disorders were measured and were compared in matched plasma, skim milk and milk fat samples at 10 days interval. The incidence rate of reproductive disorders were as follows; inactive ovaries 20(33.3%), silent heat 11(18.3%), follicular cyst 7(11.7%), luteal cyst 7(11.7%), persistent corpus luteum 7(11.7%), pyometra 4(6.7%), vaginitis 2(3.3%), cystic corpus luteum 1(1.7%), and endometritis 1(1.7%), respectively. Cows having a progesterone concentration in plasma and skim milk < 1.0 ng/ml, and in milk fat < 80.0 ng/ml were considered to have inactive ovaries or follicular cyst. Those with concentrations in plasma and skim milk ${\geq}1.0ng/ml$, and in milk fat ${\geq}80.0ng/ml$ were regarded as the cases of luteal cyst or persistent corpus luteum. Progesterone concentrations in above cows did not differ significantly between the time of initial determination and the 10 days after initial determination. But progesterone concentrations in cows with silent heat did differ significantly between the time of initial determination and the 10 days after initial determination(P<0.05). The accuracy of rectal palpation for making a differential diagnosis of ovarian dysfunction, as defined on basis of progesterone concentrations, were as follows; follicular cyst 55.6%, luteal cyst 50.0%, inactive ovaries 90.5% and persistent corpus luteum 60.0%, respectively. It may be concluded that progesterone determinations at 10 days interval is practical as an aid to diagnosing ovarian dysfunction, particularly follicular cyst and luteal cyst.

• 한국축산식품학회지
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• 제38권2호
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• pp.273-281
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• 2018

Preheating conditions (low-, medium-, and high heat-) did not significantly affect the buffering capacity (BC) of skim milk powder (SMP), whereas the level of demineralization significantly affected the BC of whey powders (WP). Heat treatment ($85^{\circ}C$ for 30 min) of both SMP and WP (90% demineralized) mixtures (88:12, 76:24, 64:36 and 52:48; SMP:WP) resulted in a reduced BC, and the extent of this reduction increased with the proportion of WP increased in the samples. High-buffering milk prepared by the addition of phosphate salts (40 mM $NaH_2PO_4$ and 60 mM $Na_2HPO_4$) delayed the rate of pH decline during yoghurt fermentation. The high-buffering yoghurt showed a significantly higher water holding capacity (WHC) than that of control yoghurt (p<0.05), as well as a more uniform and interconnected microstructure with small pore sizes than those of control yoghurt. No significant differences were found between high-buffering and control yoghurt regarding the viable bacterial counts of starter. The manipulation BC can potentially improve the quality characteristics of yoghurts, such as WHC and texture.

• Journal of Microbiology and Biotechnology
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• 제23권8호
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• pp.1084-1091
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• 2013

In this paper, two statistical methods were applied to optimize medium components to improve the production of the milk-clotting enzyme by Bacillus amyloliquefaciens D4. First, wheat bran juice, skim milk powder, and $Na_2HPO_4$ were shown to have significant effects on D4 enzyme production using the Plackett-Burman experimental design. Subsequently, an optimal medium was obtained using the Box-Behnken method, which consisted of 3.31 g/l of skim milk powder, 5.0 g/l of sucrose, 0.1 g/l of $FeSO_4{\cdot}7H_2O$, 0.1 g/l of $MgSO_4{\cdot}7H_2O$, 0.1 g/l of $MnSO_4{\cdot}2H_2O$, 0.1 g/l of $ZnSO_4{\cdot}7H_2O$, 1.52 g/l of $Na_2HPO_4$, and 172.45 g/l of wheat bran juice. With this optimal medium, the milk-clotting enzyme production was remarkably enhanced. The milk-clotting enzyme activity reached 3,326.7 SU/ml after incubation of 48 h, which was 1.76-fold higher than that of the basic medium, showing that the Plackett-Burman design and Box-Behnken response surface method are effective to optimize medium components, and B. amyloliquefaciens D4 possessed a high rennet-producing capacity in the optimal medium.

• Journal of Microbiology and Biotechnology
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• 제12권3호
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• pp.444-448
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• 2002

A $CaCO_3$-alginate beads system was developed for high cell density cultivation of Bifidobacterium longum and the cost-effective media were also screened. In batch process with $CaCO_3$, beads, two strains of B. longum showed both the highest viable cells and optical density in TPY medium, resulting in maximum optical density and viable cell counts of 12.40, $2.22{\times}10^10$ cfu/ml for B. longum ATCC 15707 and 13.71, $3.93{\times}10^10$ cfu/ml for B. longum HLC 3742. Released size distribution, according to $CaCO_3$-alginate bead size preparation, was smaller than others. These results were also examined by observing their morphology. The skim milk-based medium was most adequate to cultivate B. longum as the cheapest medium, and $10\%$ skim milk supplemented with $2\%$ glucose and $1\%$ yeast extract was a suitable medium, supporting the growth to $5.57{\times}10^10$ cfu/ml for ATCC 15707 and $6.82{\times}10^9$ cfu/ml for HLC 3742. During the long-term storage at $4^{\circ}C\;and\;-20{\circ}C$, B. longum cultivated with $CaCO_3$ beads had the highest stability. Consequently, $CaCO_3$-alginate beads buffer was found to be useful not only to cultivate B. longum but also to preserve cultures.

• Journal of Microbiology and Biotechnology
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• 제24권6호
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• pp.795-802
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• 2014

The aim of this study was to determine the effects of temperature and supplementation with skim milk powder (SMP) on the microbial and proteolytic properties during the storage of cottage cheese. Cottage cheese was manufactured using skim milk with 2% SMP and without SMP as the control, and then stored at $5^{\circ}C$ or $12^{\circ}C$ during 28 days. The chemical composition of the cottage cheese and the survival of the cheese microbiota containing starter lactic acid bacteria (SLAB) and non-starter culture lactic acid bacteria (NSLAB) were evaluated. In addition, changes in the concentration of lactose and lactic acid were analyzed, and proteolysis was evaluated through the measurement of acid soluble nitrogen (ASN) and non-protein nitrogen (NPN), as well as electrophoresis profile analysis. The counts of SLAB and NSLAB increased through the addition of SMP and with a higher storage temperature ($12^{\circ}C$), which coincided with the results of the lactose decrease and lactic acid production. Collaborating with these microbial changes, of the end of storage for 28 days, the level of ASN in samples at $12^{\circ}C$ was higher than those at $5^{\circ}C$. The NPN content was also progressively increased in all samples stored at $12^{\circ}C$. Taken together, the rate of SLAB and NSLAB proliferation during storage at $12^{\circ}C$ was higher than at $5^{\circ}C$, and consequently it led to increased proteolysis in the cottage cheese during storage. However, it was relatively less affected by SMP fortification. These findings indicated that the storage temperature is the important factor for the quality of commercial cottage cheese.

• Biotechnology and Bioprocess Engineering:BBE
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• 제6권2호
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• pp.133-138
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• 2001

In this study, an attempt was made to increase the survival rate of bifidobacteria entrapped in alginate in the gastrointestinal tract, and to investigate the potential industrial applications, for example lyophilized capsules and yogurt. First, the protective effect of various food additives on bifidobacterial survivability was determined after exposure to simulated gastric juices and bile salts. The additives used in this study were skim milk (SM), polydextrose (PD), soy fiber (SF), yeast extract (YE), chitosan (CS), $\kappa$-carageenan ($\kappa$-C) and whey, which were added at 0.6% concentration (w/v) to 3% alginate-bifidobacterial solution. In the simulated gastric juices and bile salts, the protective effect of 0.6% skim milk-3% alginate (SM-A) beads on the survival rate of bifidobacteria proved to be higher than the other additives. Second, the hydrogen ion permeation was detected through SM-A vessel without bifidobacterial cells at different SM concentrations (0.2%, 0.4%, 0.6%, 0.8%, and 1.0%). There were no differences in terms of the pH decrease in SM-A vessels at 0.6%, 0.8%, and 1.0% (w/v) SM concentrations. The survival rate of bifidobacteria in SM-A beads would appear to be related to the SM buffering capacity against hydrogen ions and its tendency to reduce the pore size of bead. In this experiment, the survival rate of bifidobacteria entrapped in beads containing 0.6% SM showed the highest viability after exposure to simulated gastric juices for 3h, thereby indicating that 0.6% SM is the optimum concentration fir 3% alginate bead preparation. Third, the effect of SM-A beads on the freeze-drying and yogurt storage for 10 days was investigated. SM-A beads were found to be more efficient for freeze drying and yogurt storage than untrapped cells and the alginate bead. Consequently, the survival rate of bifidobacteria entrapped in SM-A beads was increased in simulated gastric juices, bile salts and probiotic products, such as lyophilized capsules and yogurt, SM-A beads can be expected to produce high value probiotic products.

• 대한기계학회논문집B
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• 제26권2호
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• pp.288-301
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• 2002

A vacuum freeze drying experiment of skim milk solution in a cylindrical container is conducted to investigate the multi-dimensional drying characteristics of the process during the primary drying stage. Temperature histories at several positions are measured under the same process condition that is carefully controlled. Then the measured temperature histories at different positions are combined to produce instantaneous temperature distribution fields inside the cylindrical container. Along with the temperature measurement, the mass reduction history of the skim milk solution is also measured. From the measured temperature distribution curved configurations of sublimation interfaces and 2-dimensional heat transfer is inferred. The freeze drying under the present experimental setup is simulated with a calculation program that is based on a finite volume method with a moving grid system. Good agreements between the numerical and experimental results are observed. The present experimental results and the numerical approaches can be useful information in developing the analysis tools for practical vacuum freeze drying processes.