• 농업과학연구
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• 제20권2호
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• pp.153-166
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• 1993

원료유(原料乳)의 보전성(保存性) 향상을 위하여 원료유와 이를 $65^{\circ}C$에서 30초간 및 $75^{\circ}C$에서 2초간 가열처리(加熱處理)하여 $5^{\circ}C$의 냉장상태에서 4일간 보존(保存)하면서 이화학적(理化學的)인 성장(性狀)과 미생물학적(微生物學的)인 변화(變化)를 시험(試驗)한 결과(結果)는 다음과 같다. 1. 원료유(原料乳) 및 가열처리유(加熱處理乳)의 저장기간중의 우유성분 즉, 유지방(乳脂肪), 유단백질(乳蛋白質), 유당(乳糖) 및 총고형분(總固形分)함량의 변화는 나타나지 않았다. 2. 원료유(原料乳)의 pH와 산도의 범위는 각각 6.73~5.94 및 0.16~0.27%였으며 가열처리유(加熱處理乳)의 pH 및 산도는 각각 6.79~6.62 및 0.16~0.17%이었고 phosphatase시험결과는 모두 음성으로 나타났다. 3. 가열처리온도(加熱處理溫度)가 높아짐에 따라 총질소, NCN, 및 Whey protein의 함량은 감소한 반면 NPN과 Casein의 함량은 증가하였다. 4. 저장기간(貯藏期間)에 따른 총질소 및 Casein의 함량은 감소한 반면에 NCN과 NPN의 함량은 증가 하였으며, Whey protein의 함량에는 변화가 없었다. 5. 가열처리(加熱處理)한 원유는 대장균(大腸菌)이 검출(檢出)되지 않았으나, 가열처리(加熱處理)하지 않은 원유는 저장기간동안 점차적 증가 하였다. 6. 원료유(原料乳)의 총균수는 $5.6{\times}10^6/ml$, 내냉성미생물은 $1.8{\times}10^6/ml$, 내열성미생물은 $1.6{\times}10^5/ml$를 나타내었으나 가열처리(加熱處理) 온도(溫度)의 상승에 따라 감소하여 $75^{\circ}C$에서 2초간 가열처리(加熱處理) 하였을때는 각각 $3.0{\times}10^3/ml$, $1.5{\times}10/ml$ 및 $2.7{\times}10^3/ml$으로 감소 하였다. 7. 저장기간(貯藏期間)에 따라 원료유는 내열성미생물, 내냉성미생물 및 총균수가 크게 증가 하였으며 가열처리유(加熱處理乳)는 원료유(原料乳)에 비하여 증가되지 않았다.

• 한국식품영양과학회지
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• 제28권4호
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• pp.805-809
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• 1999

The growth of Lactobacillus casei in milk was enhanced by adding yams. Addition of 1% yam(raw or dry) promoted the cell growth and acid production in fermented milk. The milk containing 1% yams formed the complete curd by lactic acid fermentation at 37oC for 19hr while the milk without yams showed the incomplete curd formation. The crude mucilage extracted from a raw yam also enhanced the cell growth as well as the acid production. Addition of mucilage(0.08%) showed the similar effects with adding heat treated yam(1%). The milk fermented by adding various yams showed the high scores for sensory evaluation comparing with the milk fermented without yams. The fermenting ability of Lactobacillus acidophilus, Lactobacillus kefir and Leuconostoc mesenteroides was evaluated by adding 1% of a dry yam in milk. A dry yam also enhanced the cell growth of L. acidophilus resulting in the high acid production. The viable cell counts of L. casei, L. acidophilus and Leuc. mesenteroides except L. kefir were increased by adding 1% of a dry yam.

• Food Science and Biotechnology
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• 제15권6호
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• pp.844-850
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• 2006

This study was designed to compare various quality characteristics, such as nutrient composition and physicochemical and sensory properties of freeze-concentrated milk made by a newly developed continuous multi-stage process with those of evaporated milk. The freeze concentration process reduced the water content up to 73%. Most of the physicochemical properties of evaporated milk were different from raw milk; however the freeze-concentrated milk showed little difference from the raw milk. The thiobarbituric acid value and free fatty acid concentrations were significantly greater in the evaporated milk than in the freeze-concentrated milk. Several effects on sensory characteristics, such as off-taste, were significantly stronger in the evaporated milk. Overall, this study indicates that the newly developed freeze concentration technique results in improved physicochemical and sensory properties, and has little effect on most nutrient levels when compared with the evaporation process. Further research is necessary to further elucidate the chemical and sensory properties of freeze-concentrated milk.

• Journal of Microbiology and Biotechnology
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• 제16권8호
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• pp.1229-1235
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• 2006

A lab-on-a-chip (LoC) was designed for simultaneous monitoring of microorganisms, antibiotic residues, somatic cells, and pH in raw milk. The LoC was fabricated from polydimethylsiloxane (PDMS) using microelectromechanical system (MEMS) technology, which consisted of two parts; a protein array and microchannel. The protein array was fabricated by immobilizing five types of antibodies corresponding to two microorganisms, two antibiotic residues, and somatic cells. A sol-gel film was deposited on a glass substrate to immobilize the antibodies. The target analytes in raw milk could be bound with the corresponding antibody by an immunoreaction, and the antigen-antibody complex was detected using fluorescence microscopy. SNARF-dextran was used as a pH indicator, and the SNARF-entrapped hydrogel was attached to the microchannel in the chip. After injecting the milk sample into the channel, the pH was measured by monitoring the change in fluorescence intensity by fluorescence microscopy. The on-chip simultaneous assay of two microorganisms (E. coli O157:H7 and Streptococcus agalactiae), two antibiotic residues (penicillin G and dihydrostreptomycin), and neutrophils was successfully accomplished using the proposed LoC system.

• 한국축산식품학회지
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• 제37권6호
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• pp.847-854
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• 2017

A rapid, sensitive and specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous determination of four barbiturates (phenobarbital, pentobarbital, amobarbital and secobarbital) in raw milk. The barbiturates were extracted using liquid-liquid extraction, ultrasonication and centrifugation, and purified on an SPE column. Analytes were separated by HPLC on a CSH C18 column eluted using an acetonitrile-water system with a linear gradient dilution programme, and detected by MS/MS. The recoveries of the barbiturates were 85.0-113.5%, and the intra- and inter-assay RSDs were less than 9.8% and 7.3%, respectively. The limit of detection was 5 ng/mL for all four of the barbiturates. The analytical method exhibited good linearity from 10 to 1000 ng/mL; the correlation coefficient ($r^2$) was greater than 0.9950 for each barbiturate. This method was also applied to the determination of barbiturates in real milk samples and was found to be suitable for the determination of veterinary drug residues in raw milk.

• 한국동물위생학회지
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• 제30권3호
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• pp.421-428
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• 2007

This study was conducted two kinds of aims: 1) to modify the analytical methods (conditions) by high performance liquid chromatography - fluorescence detector for the detection of residual ivermectin in raw milk, 2) to provide basic information for the evaluation of standard of the residual ivermectin in raw milk. It could be considerable that negative ion spectra can be better method in the LC/MS analysis for the detection of residues, Characteristic daughter ions were observed in negative ion spectra, however, linear line was not formed in positive ion one. Three Holstein cows ($500{\pm}10kg$) were applied to commercial ointment of ivermectin just one time at the first day of test, and residues in raw milk were examined for 20day after administration. The limit of detection (LOD) was 0.65ng (n=5) by HPLC/FLD, and recovery rates were $87.85%{\sim}99.47%$. The peak was observed at the 4th day, and residues lasted to the end. Thus ivermectin was prohibited when lactating.

• 한국동물위생학회지
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• 제20권1호
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• pp.79-93
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• 1997

The sulfonamide is one of potentiative antimicrobial agents which is being used widely in veterinary medicine for control of several animal diseases such as mastitis as well as for promotion of growth. However, the misusages of sulfonamides in food producing animals, especially cattle produce several considerable problems in human health caused from residues of this antibiotic in milk product. To determine the most effective analytical methods for residual sulfonamides in raw milk, this study was performed comparatively using by some applicable screening detecting method such as TTC, Charm II test (sulfonamides), and Lactek tests (sulfamethazine kit). The positive result from screening tests was confirmed by HPLC method. Milk samples (540 raw milks) were collected from dairy farms. Results of this study are summariezed as follorrs ; 1. All samples (540 raw milks) showed negative response from TTC test, however, 18 raw milks of those samples responded positively to Charm II test. 2. By Lactek test, residual sulfamethazine was detected from 4 raw milks. Fifteen raw milks of 18 samples which were classified as positive one by Charm II test, showed positive response 3. Retention time of sulfonamides added at the level of 100ppb into sklm milk was ranged from 1.55 minute to 23.3 minute. Recovery rates of sulfonamides were variable from 6.7% upto 94.2% depended on the types of sulfonamlde. 4. Single type of sulfonamides was detected from 10 raw milk samples, 2 types of sulfonamides from 3 samples and 3 types from 2 raw milks by HPLC. 5. Sulfonamides was detected in this study were 5 types : 11 samples for sulfisomidine, 5 samples for sulfamethazine, 3 samples for sulfadlmethoxine, 2 samples for sulfathiazole and 1 sample for sulfadiazine. 6. The highest levels of residual sulfonamides was 210.3 ppb of sulfamethazine but the lowest concentration of residue was 2.2 ppb of sulfamethazine and sulfisomidine, respectively. Number of samples detected positively in this experiment were belows : above 100 ppb for 1 sample (4.5%) (sulfamethazine), 50~100 ppb for 4 samples (18.1%) (each 2 samples for sulfamethazine and sulfisomidine, respectively), 25~50 ppb for 6 samples (27.1%) (2 sulfisomidine, each 1 sample for sulfadiazine, sulfadimethoxine, sulfamethazine and sulfathiazole, respectively), 10~25ppb for 3 samples (13.7%) (3 sulfisomidine), and below 10ppb for 8 samples (36.4%) (4 sulfisomidine, 2 sulfadimethoxine and each 1 for sulfamethazine and sulfathiazole).

• 한국축산식품학회지
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• 제33권4호
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• pp.542-548
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• 2013

살균한 원유에 지방분해효소와 단백질 분해효소활성이 가장 높게 나타났던 균주를 접종하고 저장하면서 내냉성미생물이 생성하는 효소가 원유의 품질에 미치는 영향을 조사하였다. 지방분해효소활성이 높은 Acinetobacter genomospecies 10은 냉장저장기간 중 총 고형분과 유지방의 함량에 영향을 미치지 않았고, 지방의 분해는 냉장보관 14일째에 대조구와 비교하여 2.6배 이상의 유리지방산을 생성하였다. 생성된 지방산의 조성은 short chain free fatty acid(SCFFA), middle chain free fatty acid(MCFFA) 및 long chain free fatty acid(LCFFA)를 모두 생성하였으며, 특히 SCFFA와 MCFFA의 증가율이 높았다. 단백질 분해효소활성이 높은 Serratia liquefaciens은 원유의 총 고형분과 유단백질 함량에 영향을 미치지 않았고, 단백질 조성의 변화는 냉장저장기간 동안 케이신의 함량이 서서히 감소하다가 10일째부터 $\kappa$-케이신의 함량이 현저히 감소하였다. 유리아미노산은 대조구와 비교하여 냉장저장 14일째 2.8배 이상 생성되었으며 특히 소수성 아미노산으로 쓴맛을 내는 leucin, valine 등의 함량이 급격히 증가하였다.

• Journal of Nutrition and Health
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• 제29권9호
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• pp.1042-1048
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• 1996

In order to investigate heating rate of commercial milk products in korean market, lactulose content and availability of calcium and ascorbic acid were measured. The pH range for raw and commercial milk was 6.5-6.75, and protein content was 2.5-3.13%. The acid degree value (。SH)showed between 5.3 and 7.1. There were no differences in pH, protein and acid degree among 3 types of milk. The portion ionic Ca content in UHT-milk(32.4%) and pasteurized milk (27%) increased significantly in comparison with raw milk (4.6%). Pasteurization led to loss of 20% ascorbic acid, and losses of UHT-treatment are approximately twice as high. Significant differences of lactulose content between UHT milk and pasteurized milk were observed. Some of UHT milk products showed very high value of lactulose content like sterilized milk. It is well known that the stress caused by indirect UHT treatment is slightly higher compared with the direct process. The results in this experiment suggested that most of UHT milk in korean market may be treated by indirect UHT method. In oder to keep the adventages of milk component, the heating methods of milk have to be reconsidered.

• Journal of Dairy Science and Biotechnology
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• 제22권2호
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• pp.131-141
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• 2004

The FTA(Free Trade Agreements) are loading the world trade liberalization. Entering into FTA with Chile on 1 Apr 2004, Korea is trying to tie with Singapore and Japan in FTA. It also has a long-term plan for free-trading with China, USA, ASEAN, Canada and India. The portion of the dairy products imported from Chile, Japan and Singapore is under 1% of total dairy product imports. However, in the long run the conclusion of FTA with dairy product exporting countries such as USA, Australia, New Zealand and Netherlands will give a big impact on the dairy industry with abrupt increment in dairy product imports. Especially, whole and skim milk powder imports which are imported on the high tariff rate expect to increase. Furthermore mixed milk powder(Food preparations of goods and other whey powders) imports which domestic price is higher than world market also will dramatically increase. The milk powder stocks have increased since 2002. That made the government carry out some policies. Those include slaughtering milking cow(2002) and terminating the dairy farm enterprise and decreasing in milk production(2003). Also the case of artificial insemination by a Hanwoo fertilized egg has increased with the rise of Hanwoo farm price in 2003. By those reason, it is forecasted that the downward trend in the number of cow will be continued in 2004. It is also forecasted that the raw milk production in 2004 will decrease 4.4% compared to last year due to decreasing in the number of milking cow and raw milk collecting quota.