• 한국조리학회지
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• 제24권1호
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• pp.24-30
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• 2018

This study investigated the quality of characteristics of high-protein RTD coffee using domestic and imported skim milk powder with different heat treatment. Skim milk powders (A, B) had high-heat treatment, C had medium-heat, and D and E had low-heat treatment. The transmittance of A and B were higher than that of C, and that of C were higher than that of D and E (p<0.05). The precipitate attached on bottom of container of RTD coffee using A and B were 2.993~3.053% and higher than those (0.753~0.803%) of RTD coffee using C, D and E (p<0.05), but there was no difference between those of RTD coffee using C, D and E (p<0.05). The centrifuged precipitate of RTD coffee using A and B were 1.987~2.040% and higher than those (0.820~0.830%) of RTD coffee using C, D and E (p<0.05), but there was no difference between those of RTD coffee using C, D and E (p<0.05). The proximate composition of precipitate attached on bottom of container of RTD coffee using A, which showed the highest amount of precipitate, showed 65.7% of carbohydrate, 19.0% of protein, 4.8% of fat and 4.8% of ash in dry basis, that of RTD coffee being 72.7%, 15.1%, 7.9% and 4.3% in dry basis respectively. Protein and fat content of precipitate were lower and protein and ash content were higher than those of RTD coffee. But seeing that the most increased portion was protein, precipitation of RTD coffee appears to be attributed to heat-denatured proteins.

• 한국축산식품학회지
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• 제31권2호
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• pp.158-165
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• 2011

A sensitive reverse transcriptase-PCR (RT-PCR) method to detect viable Escherichia coli O157:H7 in milk was established. The primer sets were designed based on the nucleotide sequences of the rfbE (per) and wbdN genes in the O157 antigen gene cluster of E. coli O157:H7. RT-PCR using five different primer sets yielded DNA with sizes of 655, 518, 450, and 149-bp, respectively. All five of the E. coli O157:H7 strains were detected by RT-PCR, but 11 other bacterial species were not. The sensitivity of RT-PCR was improved by adding yeast tRNA as a carrier to the crude RNA extract. The RT-PCR amplifying the 149-bp DNA fragment was the most sensitive for detecting E. coli O157:H7 and the most refractory to the bactericidal treatments. Heat treatment at $65^{\circ}C$ for 30 min was the least inhibitory of all bactericidal treatments. Treatment with RNase A strongly inhibited the RT-PCR of heated milk but not unheated milk. This study described RT-PCR methods that are specific and sensitive with a detection limit of 10 E. coli O157:H7 cells, and showed that pre-treating milk samples with RNase A improved the specificity to detect viable bacteria by RT-PCR.

• Journal of Dairy Science and Biotechnology
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• 제26권1호
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• pp.27-36
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• 2008

This review was written to introduce updated data on the structure and function of the major milk proteins identified as allergens, the characterization of their epitopes in each allergenic milk proteins, and the reduction of milk protein allergenicity. Most mammalian milk protein, even protein present at low concentration, are potential allergens. Epitopes identified in milk proteins are both conformational(structured epitope) and sequential epitopes(linear epitope), throughout the protein molecules. Epitopes on casein and whey proteins are reported to be sequential epitope and conformational epitopes, respectively. Conformational epitopes on whey protein are changed into sequential epitope by heat denaturation during heat treatment. Several methods have been proposed to reduce allergenicity of milk proteins. Most ideal and acceptable method to make hypoallergenic milk or formula, so far, is the hydrolysis of allergenic milk proteins by enzymes that has substrate specificity, such as pepsin, trypsin, or chymotrypsin. Commercial formulas based on milk protein hydrolysate are available for therapeutic purpose, hypoantigenic formula for infants from families with a history of milk allergy and hypoallergenic formula for infants with existing allergic symptoms.

• Asian-Australasian Journal of Animal Sciences
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• 제16권8호
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• pp.1212-1217
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• 2003

Fifty-two Holstein cows with different phenotypes of $\kappa$-casein ($\kappa$-CN) and $\beta$-lactoglobulin ($\beta$-LG) were selected to provide weekly milk samples for heating at 30, 70, 75 and $80^{\circ}C$ for 2 min. Coagulating properties of heated milk samples measured as rennet clotting time, rate of curd firming and curd firmness at cutting were determined by a Formagraph. Milk samples were analysed for fat and casein. Least squares analyses of data, after adjustments were made for effect of milk casein and fat contents, indicated that although an increase in heating temperatures resulted in less desirable coagulating properties, the effect of milk types was inherent irrespective of heating temperatures. The shortest rennet clotting time (6.06 min), fastest rate of curd firming (5.61 min) and firmest curd (38.05 mm) were obtained from milk with the B variant for $\kappa$-CN and B variant for $\beta$ -LG when preheated at $30^{\circ}C$. It appears that milk bearing $\kappa$-CN B is more resistant to heat perturbation. All milk samples having the $\kappa$-casein AA (milk types AA/AA, AA/AB, AA/BB) did not have a measurable K20 value when preheated at $70^{\circ}C$. This effect was observed for $\kappa$-casein AB (milk types AB/AA, AB/AB, AB/BB) at $75^{\circ}C$ and $\kappa$-casein BB (milk types BB/AA, BB/AB, BB/BB) at $80^{\circ}C$.

• Journal of Dairy Science and Biotechnology
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• 제22권1호
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• pp.27-35
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• 2004

The shelf lift of market milk should be determined based on the flavor which is influenced by environmental and sanitary conditions of dairy farm, milk processing plant, and storage and transportation facility as well as compositional quality, such as protein and fat, of the milk itself. The legal shelf life of market milk is often limited by microbiological quality, e.g. total bacterial count, coliform count, and food poisoning bacteria. The bacteria involved with milk spoilage and poisoning are originated from bacteria contaminating milk after pasteurization or spores surviving the heat treatment of pasteurization. The important factors which influence the shelf life of market milk are microbiological quality of raw milk, pasteurization condition, post-pasteurization contamination, and temperature during storage and transportation. The organoleptic quality and shelf life of market milk should be further improved by satisfying the consumer's taste, which depends on somatic cell count and bacterial count of milk, feed quality, foreign substance in milk, and physical treatment during processing and transportation.

• 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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• 제37권1호
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• pp.81-81
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• 2019

• Journal of Dairy Science and Biotechnology
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• 제37권1호
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• pp.82-82
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• 2019

• Asian-Australasian Journal of Animal Sciences
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• 제30권12호
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• pp.1711-1717
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• 2017

Objective: This experiment was studied the effects of various levels of crude glycerin (CG) in dairy goat diet on daily intake, milk yield, milk composition, some physical properties and some quality changes of goat milk after sterilization. Methods: Twelve 75% Saanen dairy goats (body weight = $49{\pm}3kg$; days in milk = $60{\pm}12d$) were randomly assigned in a completely randomized design to evaluate the effects of three experimental diets consisting of 0%, 5%, and 10% CG (dry matter basis) which were formulated to meet or exceed the nutrient requirements of goats. Experimental dairy goats were evaluated for feed and milk yield. Milk samples were analyzed for their composition, including fatty acids, casein profile, fat globule size, and color, and were sterilized to evaluate milk heat stability. Results: There were no significant differences between 0% and 5% CG treatments infeed. Increasing CG supplementation from 0% to 5% increased milk yield from $2.38{\pm}0.12$ to $2.64{\pm}0.23kg/goat/d$. In addition, milk samples from 5% CG treatment had the highest total solids, fat content and lactose content, and largest fat globule size. Increasing CG to 10% resulted in a decrease in milk fat. After sterilizing at $116^{\circ}C$, $F_0=3min$, goat milk samples from 5% CG treatment had slightly higher sediment content and comparatively higher degree of browning. Conclusion: Considering milk yield, milk fat content and quality of sterilized milk, 5% CG supplementation in a total mixed ration has a potential for implementation in dairy goats.

• 한국축산식품학회지
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• 제22권2호
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• pp.172-178
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• 2002

우유 중에는 여러 종류의 생리활성물질과 우리 몸에 꼭 필요한 비타민이 매우 소량 함유되어 있어, 그 강화를 목적으로 유가공 산업의 발전과 더불어 다양한 비타민 강화우유가 소개되고 있다. 이에 본 연구에서는 가공 처리 및 비타민 강화 방법에 따른 비타민류의 손실율을 조사하였다. 실험 결과, UHT 처리 후에 비타민 C는 60~70% 가까운 손실율을 보였으며, 비교적 열에 안정하다고 알려진 지용성 비타민인 비타민 D$_3$와 비타민 E도 30~40%의 손실율을 보여 주었다. 이에 반해 비타민을 캡슐 형태로 강화하였을 경우에는 수용성 비타민의 손실율은 상대적으로 매우 낮음을 알 수 있었다. 이는 캡슬에 의해 열뿐 아니라 산소, 빛 등이 효과적으로 차단되어 비타민의 손실이 최소화된 것이라 생각된다. 따라서 열처리에 의한 시유 및 강화우유 중의 비타민의 손실을 최소화하기 위해서는 우유의 살균 온도 및 시간, 강화제 첨가 방법 등에 대한 지속적인 연구가 이루어져야 할 것으로 사료된다.