• 한국미생물·생명공학회지
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• 제22권1호
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• pp.13-17
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• 1994

We estabilished the procedure for isolation of Streptococcus salivarius subsp. thermophilus from raw milk. First, urease-producing lactic acid bacteria in raw milk were screened on the HY agar medium containing urea. Thereafter the urease-producing colonies were tested the ability to ferment maltose and to grow at43$\circ $C. We obtained about 400 maltose-negative colonies that grew at 43$\circ $C. No significant difference in carbohydrate fermentation test for isolated and type strains(S. salivarius subsp. thermophilus ATCC 19258 and ST-4) was found. And all of the isolated strains were able to ferment galactose. Furthermore, it was investigated that the cellular fatty acid profiles of isolated strains were similar to that of type strains. These results indicated that the isolated strains from raw milk were S. salivarius subsp. thermophilus. But when the isolated and type strains were incubated in 12% reconstituted skim milk at 43$\circ $C, the isolates produced lactic acid more slowly than the type strains.

• Journal of Dairy Science and Biotechnology
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• 제24권1호
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• pp.43-51
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• 2006

Producer prices of raw milk include following elements: a basic price, payment according to fat content, payment according to bacteriological quality and somatic cell count. The quality of raw milk has increased since last change of payment system according somatic cell count. But last change of payment system according to fat content is not effective. It is necessary to widen the range of equal price by fat content. Also it is necessary to include payment according to protein content.

• Journal of Dairy Science and Biotechnology
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• 제15권1호
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• pp.45-51
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• 1997

Korea dairy industry is placed on the very critical situation with the progression of free trade marketing system internationally. The sterilized milk or pasteurized extended shelf life milk can be considered as the international trade dairy products. Now all dairy foods would be selling in international market. To keep and improve our dairy foods market, the Korea dairy system improvement committee was inaugurated in 1995. This committee has done so many works to improve or dairy system such as the settlement of raw milk supply and demand, centralization of raw milk collection, ideal raw milk price system and dairy foods marketing structure, etc.

• 한국동물위생학회지
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• 제24권1호
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• pp.89-94
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• 2001

In order to investigate the relationship between milk hygienic quality and some environmental factors such as the herd size and types of milking machines, we sampled and examined the level of total bacterial count, coliforms, Staphyococcus aureus, somatic cell counts(SCC) and fat rates in raw milk. of the 84 dairy farms, the prevalence of level on number of standard plate count over 100,000cfu/$m\ell$ and coliforms over 1,000cfu/$m\ell$ in bulk milk were 25.0% and 15.6%, respectively. Also, 2 farms(2.4%) were exceed the level on number of 500cfu/$m\ell$ S aureus in raw milk. The prevalence of dairy herd with first grade of total bacterial count(TBC) according to bucket, pipe line and parlour milking system was 40.0%, 74.0% and 84.0%, respectively. The prevalence of dairy herd with first grade of TBC according to grade 1, 2 and 3 by SCC was 77.8%, 83.2%. and 69.2%, respectively. Therefore, the relationships between hygienic quality in raw milk and the herd size, types of milking machines, were significant. In conclusion, this study could be overemphasized the importance of herd management condition for milk hygienic qualify.

• Journal of Dairy Science and Biotechnology
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• 제40권4호
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• pp.151-162
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• 2022

Although many developed countries (USA, Canada, and several EU countries) allow raw milk cheese to be aged more than 60 days, these countries have strict standards for the aging conditions, such as temperature, of raw milk cheese. Spiking experiments were conducted with Camembert cheese made from raw milk, to assess the microbiological safety of raw milk cheese aged for more than 60 days. We spiked Escherichia coli O157:H7 into raw milk with different inoculation levels (high, medium, and low). Camembert cheese was prepared from the inoculated raw milk, then aged in an incubator for up to 9 weeks (63 days). There were no significant differences in pH and water activity (aW) between uninoculated cheese and cheese samples inoculated with E. coli O157:H7 (p<0.05). The pH and aWof the Camembert cheese decreased throughout the storage period. In conclusion, E. coli O157:H7 did not affect the pH and aW of the cheese samples. Cell counts were conducted every week using the agar-plating method. Inoculated cells were completely eliminated, especially in Camembert cheese, after 60 days, and the reduction rate of cells was much faster in Camembert cheese.

• 한국환경보건학회지
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• 제30권1호
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• pp.29-40
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• 2004

This study was performed to investigate and assess the composition of mineral and macronutrient contents in Korean cow′s milk.48 individual farm raw milk, 10 plant raw milk and 29 market milk were collected from June to August in 2003. The minerals such as calcium(Ca), potassium(K), magnesium(Mg), sodium(Na), zinc(Zn), iron(Fe) and phosphorus(P) were determined by using atomic absorption spectrometer(AAS). The macronutrients such as fat, protein and lactose were tested by using IR spectrometer. The obtained analytical results of minerals(mg/100 g) and rnaetronutrients (％) are as follows：1. In case of raw cow′s milk ； Ca 113.56, K 144.09, Mg 10.86, Na 42.53, Zn 0.42, Fe 0.030, p 113.32, fat 3.85, protein 3.08, lactose 4.80,2. In case of market cow′s milk ; Ca 103.04, K 142.46, Mg 10.27, Na 43.21, Zn 0.40, Fe 0.034. p 97.30, fat 3.78, protein 3.05, lactose 4.70,3. In case of fortified market cow′s milk ; Ca 165.40, K 145.79, Mg 10.57. Na 42.55, Zn 0.57, Fe 0.414, p 94.68, fat 3.74, protein 3.08, lactose 4.68,4. In case of processed market cow′s milk ; Ca 134.72, K 142.74, Mg 10.33, Na 45.07, Zn 0.50, Fe 0.650, p 92.48, fat 3.72, protein 3.07, lactose 4.74. According to the group of market milk(milk, fortified market row′s milk, processed market cow′s milk), the mean concentration of Ca and Fe were significantly higher in fortified and processed milk than milk(p<0.05). There were no significant differences in macronutrient(fat, protein, lactose) and mineral contents between pasteurized milk and UHT(ultra high temperature) treated milk($\alpha$=0.05). The labeled "Nutritional Facts" of market milk were satisfied with "Labeling Standards for Livestock Products of Korea". The measured mean concentrations of Ca, Fe, Zn were generally higher than lower limit of labeled value(above 80% of labeled value). The mean concentration of sodium was lower than upper limit of labeled value(below 120％ of labeled value).

• Asian-Australasian Journal of Animal Sciences
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• 제20권6호
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• pp.989-993
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• 2007

A lactose-hydrolyzed milk with low sweetness was developed using nanofiltration. Raw milk was treated with 0.03% ${\beta}$-galactosidase at $4^{\circ}C$ for 24 h to hydrolyze lactose partially. The resultant lactose-hydrolyzed milk containing 0.43% lactose was then concentrated using a nanofiltration membrane to reach concentration factor of 2.13. The concentration factors and coefficients of retention of milk components in nanofiltration were determined. The concentration factor of milk fat was 2.20 which was the highest of the milk components. The coefficient of retention of calcium and riboflavin was 0.96 and 0.76, respectively. However, the coefficient of retention of glucose, galactose, and sodium was 0.21, 0.15, and 0.22, respectively. Raw milk was treated with 0.1% ${\beta}$-galactosidase at $4^{\circ}C$ for 40 h to hydrolyze lactose fully and then concentrated to reach a concentration factor of 1.6 by using nanofiltration. The concentrated milk was reconstituted with water. The lactose-hydrolyzed milk had sweetness similar to milk. The compositional ratios of crude protein, calcium, sodium, and riboflavin of lactose-hydrolyzed nanofiltrated milk to those of raw milk were 99%, 97%, 77%, and 80%, respectively. This study showed that nanofiltration of lactose-hydrolyzed milk to remove galactose and glucose did not cause significant loss of calcium. The lactose-hydrolyzed nanofiltrated milk contained 0.06% lactose and had sweetness similar to milk.

• Journal of Dairy Science and Biotechnology
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• 제29권1호
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• pp.59-63
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• 2011

This study was carried out to investigate the change of components which raw milk has during cold storage. General component content of raw milk (fat, protein, lactose, total solids) was decreased in proportion to the length of cold storage. The pH of raw milk was decreased in according to the length of cold storage. In electrophoresis images, ${\beta}$-casein which was one of the composition of raw milk was decreased as the period of cold storage extended on the other hand, the content of Ca and P in the serum casein was increased in accordance with the length of cold storage.

• Journal of Dairy Science and Biotechnology
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• 제40권4호
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• pp.163-172
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• 2022

Although the USA, Canada, and several EU countries allow raw milk cheese to be aged more than 60 days, these countries have strict standards for its aging conditions, such as temperature. Many developed countries have employed standards of identity which effectively prevent the manufacture and sale, of cheese made from unpasteurized milk (i.e., raw milk) in interstate commerce, unless such cheese has been aged for a minimum of 60 days. The microbiological safety of raw milk Camembert cheese, aged for more than 60 days, was evaluated using spiking experiments. We spiked Listeria monocytogenes into raw milk with different inoculation levels (high, medium and low). Camembert cheese was prepared from the inoculated raw milk, then aged in an incubator for up to 9 weeks (63 days). The number of cells was determined every week using the agar-plating method. Inoculated cells were completely eliminated, especially in Camembert cheese, after 60 days, and the reduction rate of cells was much faster in Camembert cheese. There were no significant differences in pH and water activity (aW) between the uninoculated cheese and the cheese samples in which Listeria monocytogenes was inoculated (p<0.05). The pH and aW of the Camembert cheese decreased throughout the storage period. In conclusion, the pathogenic bacteria used in this study did not affect the pH and aW of the Camembert cheese samples.

• 대한수의학회지
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• 제36권1호
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• pp.119-129
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• 1996

The present study was conducted to rapidly detect Listeria monocytogenes in raw milk. Specificity and sensitivity of polymerase chain reaction(PCR) technique, and direct PCR were examinded in raw milk, also were compared the calssical culture methods with PCR technique. This method used a pair of primers based on a unique region in the 16S rRNA sequence of L nomocytogenes. In the PCR specificity tests, each of the 10 strains of L monocytogenes tested gave a single 70-bp band. But the other six Listera spp tested gave negative results. Results of the sensitivity tests showed that as few as 2 CFU of L monocytogenes in pure cultures could be detected with 16S rRNA-based primers, L-1 and L-2. In different PCR cycles, a PCR product was detected with $10^3$ cells of L monocytogenes from 25 cycles to 50 cycles and the concentration of PCR products was cycle-dependent. Raw milk samopes added L monocytogenes cells gave negative results. However, these samplers gave a single 70-bp band by pretreatment of pronase, and PCR products were detected with $10^1$ cells of L monocytogenes. To detemine the most sensitive culture protocol to use in conjunction with the PCR assay, raw milk samples were inoculated with L monocytogenes at concentrations ranging from 1 to $5.7{\times}10^4CFU/ml$. PCR assays from Listeria enrichment broth(LEB) containing raw milk samples added L monocytogene EGD could dtect 10 cells in pronase-pretreated samples without incubation, and 1 cell of L monocytogenes in both 12 hr and 24 hr incubation, respectively. Isolation raw of PCR assays was similar to that of classical culture methods, but required time for detection of L monocytogenes could remarkably be reduced compare to culture methods.