• Korean Journal of Veterinary Service
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• v.23 no.2
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• pp.165-170
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• 2000

This study was carried out to investigate the changes of physical and chemical properties according to the preserving periods and temperature in heat-treated market milks ($130^{\circ}C$, 2 sec). The market ilks were divided into 3 experimental groups, that is $4^{\circ}C$, $15^{\circ}C$ and $30^{\circ}C$ according to the preserving temperature during 7 days. There were analysed fat, protein, lactose, total solids, solids-not-fat, specific gravity and acid value of market milks in each experimental group. These observations indicated that heat-treated market milks ($130^{\circ}C$, 2 sec) may be acceptable physically and chemically after 7 days at $4^{\circ}C$. The results obtained were summarized as follows ; 1. Total microorganisms in market milks were found 12$\times$$10^1$ cells at 1st day Coliform and pathogenic bacteria were not detected. 2. Milk fats tended to decrease 3.69% to 3.48% according to the time lapsed in all experimental groups without concerning to the storage temperature. 3. Milk proteins were slowly decreased 3.18% to 3.13% according to the time lapsed without concerning to the storage temperature. 4. Milk lactose was slightly increased 4.41% to 4.55% in all experimental groups. 5. Specific gravity in market milks was 1.0316 to 1.0299, and showed no changes according to the preserving periods and temperature. 6. Total solids and solids-not-fat in market milks were slightly decreased 12.30 to 12.05 and 8.55 to 8.40. 7. Acid values were dramatically increased 0.1289 to 0.3116 at $30^{\circ}C$ storage group, while tended to be stable at $4^{\circ}C$ storage group for 7 days.

• Journal of the Korean Society of Food Science and Nutrition
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• v.19 no.4
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• pp.330-334
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• 1990

The lactulose contents in market milks were analyzed by gas chromatographic method. The method is evaluated for accurac and reproducibility using phenyl-$\beta$-D-glucoside as an internal standard. The response factor(RF) of lactulose of standard mixture was 1.15 the recoveries were 97.4-101.3% and the reproducibility was determined on the coefficeitns of variation 24.8% for pasteurized milk and 4.6-4.9% for UHT milk The lactulose contents of 16 brands of the market milks determined were 5.3-59.7mg/100ml in UHT milk and 1.3-1.8mg/100ml in pasteurized milk.

• Journal of the Korean Society of Food Science and Nutrition
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• v.20 no.6
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• pp.546-550
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• 1991

Changes of pH, titratible acidity, undenatured whey protein contents and the rates of loss of available lysine in market milks were investigated to find out the effective indicators for identification and classification of different heat treatment. There showed no change of both pH and titratiable acidity among the heating methods in market milks. The contents of undenatured wheyprotein per 100ml serum were determined as 413.7mg(LTLT), 341.3mg(HTSP), 6.9mg(UHT pasteurized) and 96.6mg(UHT sterilized), respectively. Distinct differences of underatured whey protein contents accoriding to the heating method could be observed. The rates of loss of available lysine in heated milks compared to raw milk showed 1.4% (LTLT), 0.2%(HTST), 6.3%(UHT pasteurized) and 4.9%(UHT sterillized), respectively. The rates of loss of available lysine were not suitable to classify the UHT heating method.

• Food Science of Animal Resources
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• v.35 no.4
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• pp.459-465
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• 2015

Bovine milk provides essential nutrients, including immunologically important molecules, as the primary source of nutrition to newborns. Recent studies showed that RNAs from bovine milk contain immune-related microRNAs (miRNA) that regulate various immune systems. To evaluate the biological and immunological activity of miRNAs from milk products, isolation methods need to be established. Six methods for extracting total RNAs from bovine colostrums were adopted to evaluate the isolating efficiency and expression of miRNAs. Total RNA from milk was presented in formulation of small RNAs, rather than ribosomal RNAs. Column-combined phenol isolating methods showed high recovery of total RNAs, especially the commercial columns for biofluid samples, which demonstrated outstanding efficiency for recovering miRNAs. We also evaluated the quantity of five immune-related miRNAs (miR-93, miR-106a, miR-155, miR-181a, miR-451) in milk processed by temperature treatments including low temperature for long time (LTLT, 63℃ for 30 min)-, high temperature for short time (HTST, 75℃ for 15 s)-, and ultra heat treatment (UHT, 120-130℃ for 0.5-4 s). All targeted miRNAs had significantly reduced levels in processed milks compared to colostrum and raw mature milk. Interestingly, the amount of immune-related miRNAs from HTST milk was more resistant than those of LTLT and UHT milks. Our present study examined defined methods of RNA isolation and quantification of immune-specific miRNAs from small volumes of milk for use in further analysis.

• Korean Journal of Food Science and Technology
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• v.25 no.4
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• pp.404-406
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• 1993

In order to detect the gelation of ultrahigh temperature (UHT) treated market milks during storage at 20+1C, the free amino groups were quantified with 2,4,6-trinitrobenzene sulfonic acid, and the measurement of pH values and the alcohol test were monthly carried out. The average tree amino groups were $0.94{\sim}1.11{\mu}M$ at 1 month, $1.95{\sim}2.17{\mu}M\;at\;5{\sim}6$ month and $4.95{\sim}6.36{\mu}M$ at 12 month. The pH values at the same time as above were $6.72,\;6.49{\sim}6.55\;and\;6.14{\sim}6.16$, respectively. The alcohol test showed positive results at $5{\sim}6$ month, which could indicate the casein instability and beginning of gelation. These results suggest that the gelation of UHT market milks could he predicted through checking some chemical parameters weekly and be helpful for quality control.

• Journal of Korean society of Dental Hygiene
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• v.13 no.4
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• pp.701-711
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• 2013

Objectives : The aim of this study was to evaluate the pH and buffering capacity in some commercial fermented milks in Korea. Methods : The study was carried ouf from June to August, 2012. In 35 liquid type, 79 condense-stirred type and 71 condense-drink type fermented milks, available on the market, pH and buffering capacity were measured. Titration(with NaOH) was used to determine the buffering effect of each fermented milk. They were titrated with 1 M sodium hydroxide, added in 0.1 milliliters increments, until the pH reached about 5.5 and 7.0. Results : The average pH of tested fermented milks was $4.08{\pm}0.27$. The average pH values of fermented milks were $3.64{\pm}0.22$ in liquid type, $4.14{\pm}0.12$ in condense-stirred type, and $4.22{\pm}0.17$ condense-drink type. The average buffering capacity (pH 5.5) of tested fermented milk was $2.40{\pm}0.54$. The average buffering capacity (pH 5.5) of liquid type fermented milk was $2.37{\pm}0.33$, condense-stirred type fermented milk was $2.77{\pm}0.46$ and condense-drink type fermented milk was $2.01{\pm}0.42$. The average buffering capacity (pH 7.0) of tested fermented milks was $4.00{\pm}0.87$. The average buffering capacity (pH 7.0) of liquid type fermented milk was $3.11{\pm}0.36$, condense-stirred type fermented milk was $4.78{\pm}0.55$ and condense-drink type fermented milk was $3.58{\pm}0.59$. Conclusions : The average pH of tested fermented milks in this study was lower than pH 4.5. The type of fermented milks was an important factor for selection of fermented milk which is related with enamel erosion.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.2
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• pp.161-164
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• 1993

To find out the effective indicators for identification and classification of different heat treatment, the contents of nitrogen fractions and the degrees of whey protein denaturation in market milks were investigated by Kjeldahl method. The contents of nitrogen fractions per 100ml raw milk were total nitrogen (431.3mg), casein nitrogen (341.0mg) and non-casein nitrogen(90.3mg), in which non-protein nitrogen (31.6mg) and denatured whey protein nitrogen (58.8mg), while those of LTLT, HTST, UHT pasteurized and UHT sterilized showed different values. The degrees of whey protein denaturation were 26.7%(LTLT), 32.9%(HTST), 60.7%(UHT pasteurized) and 38.4%(UHT sterilized), respectively. As the higher temperature was applied for the treatment of milk, the degree of the whey protein denaturation was higher. Remarkable differences in the degree of whey protein denaturation according to the heating methods were observed.

• Journal of Dairy Science and Biotechnology
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• v.16 no.2
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• pp.90-97
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• 1998

This study was carried out to investigate changes of microbiological and sensory properties in various heat-treated market milks (LTLT, HTST, and UHT milks) stored at 10$^{\circ}C$ during 15d. Titratable acidity (TA) increased with storage, while pH tended to decrease. During the initial 9d, no difference was found in TA, however, after 9d, it was slightly higher in HTST and UHT milks than that in LTLT milk. In LTLT and HTST milks, total viable cells and psychrotrophs were dramatically increased during storage, In addition coliform and pathogenic bacteria were found at 12 and 15d. In UHT milk, total viable cells were found only at 15d. In sensory evaluation, LTLT and HTST milks developed a negligible off-flavor until 9d. At 12d, it became stronger in HTST milk than that in LTLT milk. In UHT milk, off-flavor was detected at 9d and increased rapidly there-after. The degree of off-flavor was little higher in HTST and UHT milks, compared with that of LTLT milk after 9d storage. These observations indicated that LTLT and HTST milks may not be microbiologically acceptable after 5d, while off-flavor was not detectable until 9d, In comparison, UHT milk keeps a good quality in microorganism until 15d, however, it may not be accepted in sensory aspect after 9d storage.

• Food Science of Animal Resources
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• v.22 no.3
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• pp.247-251
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• 2002

This study was carried out to investigate the keeping quality of market milks collected from several dairy processing companies. Microbiological, chemical, and sensory properties of Intra-high temperature(UHT) treated milks stored at 5, 10, 15t were evaluated during the storage of 154days. No significant difference during the storage was shown in bacterial counts, pH and titratable acidity. Standard plate count(SPC) was remained less than 20,000 cfu/ml after 15 day storage at 5, 10, 15$^{\circ}C$. Also, Psychrotrophic bacterial count and Coliform count were not detected or detected at low level. The pH ranged from 6.55 to 6.83 and the titratable acidity ranged from 0.13% to 0.16%. In sensory evaluation, UHT milks showed normal flavor until 10days, but thereafter off-flavor was slightly developed. Consequently, UHT milks remained in good quality when stored at 5$^{\circ}C$,10$^{\circ}C$t until 15days except sensory properties. According to this experiment, the shelf-life of UHT milk can be extended to 10 days, even though maintaining the storage temperature strictly below 10 t in milk market is not easy.

• Journal of Nutrition and Health
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• v.10 no.1
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• pp.44-48
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• 1977

The purpose of this experiment was performed for ascorbic acid contents of market milk in Seoul city area during the period of two seasons from spring (April, 13 to 30) to summer (July, 5 to 16) 1976. The samples were collected into five groups (A,B,C.D and E) according to factory products of market milks. The results obtained were as follows : 1. On an average, the value in spring was significantly lower than in summer, that is $0.228{\pm}0.222\;and\;0.374{\pm}0.028\;mg/100ml,$ respectively. 2. The differences among the groups of each factory product showed highest in C,A group and lower in E, B and D group. Thus, there were statistically significant (p<0.01) among-them.