• Journal of Dairy Science and Biotechnology
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• 제32권2호
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• pp.63-70
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• 2014

Automatic milking systems (AMS) have been increasingly introduced to Korean dairy farms. However, in comparison with conventional milking systems (CMS), some negative changes in milk quality are being observed. The use of AMS leads to an increase in milking frequency, which in turn might result in higher physical stress on the milk, possibly causing changes in the milk fat globule (MFG) membrane. Therefore, the purpose of this study was to examine the effect of the different milking systems on the milk quality, with a focus on milk fat properties. At the same time, we studied the effect of feeding the dairy cows with protected fat. Raw milk samples were taken monthly from individual cows as well as from bulk tanks at four AMS and four CMS dairy farms. We measured quality-related parameters such as MFG size distribution, free fatty acid content and composition, and acid values. Although most results showed no significant differences with regard to the milking system, we found a relatively high positive correlation between MFG size and milk fat content. Moreover, larger MFG size was observed in the milk when cows had been fed protected fat. The significantly higher (P< 0.05) free fatty acid content of milk observed under this experimental condition could be attributed to higher milking frequency as a result of using AMS.

• 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.

• Journal of Dairy Science and Biotechnology
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• 제33권3호
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• pp.209-214
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• 2015

AMS와 CMS 및 보호지방의 급여 여부가 우유 성분과 유지방 특성에 미치는 영향을 조사하기 위하여 본 연구를 실시하였다. 착유방식과 보호지방 급여 여부에 따라 AMS 및 CMS 목장을 각 4개소씩 선정하여 월 1회 집합유 원유시료를 채취하였으며, 총 5개월간 유성분, 유지방구(MFG) 크기, 지방산 및 유리지방산 조성을 분석하였다. 착유방식에 따른 일반 유성분, MFG 크기, 지방산 조성의 유의적 차이는 관찰되지 않았으나, AMS로 착유된 우유의 유리지방산 함량이 CMS로 착유된 우유에 비해 유의적으로(p<0.05) 높았으며, 이는 AMS 의 착유 횟수가 CMS에 비해 더 많았기 때문인 것으로 판단된다. 보호지방을 급여한 농장의 우유를 비급여 농장과 비교하였을 때 유성분에는 차이가 없었으나 장쇄지방산(LCFA) 함량이 더 높은 것으로 나타났으며, 유지방구의 크기 또한 증가하는 경향을 보였는데 이는 급여한 보호지방의 주요지방산인 LCFA가 유지방으로 전이되었기 때문으로 해석된다. 또한 공시한 모든 AMS 목장에서 원유의 산패문제는 발생하지 않았는데, 유리지방산 함량이 CMS에 비해 유의적으로 높았지만 산패를 일으킬 정도로 높은 수준은 아니었던 것으로 판단된다. 이상의 결과를 바탕으로 할 때 AMS는 유성분 및 유지방 특성의 측면에서 CMS 대비 주목할 만한 차이를 보이지 않았으며 보호지방의 급여는 유지방구 크기 및 장쇄지방산 농도에 영향을 미치므로 향후 목장형 유가공을 실시할 경우 이를 응용할 여지가 있을 것으로 사료된다.

• Asian-Australasian Journal of Animal Sciences
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• 제27권6호
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• pp.886-897
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• 2014

The aim of the present study was to get a total physical and chemical characterization and comparison of the principal components in Bangladeshi buffalo (B), Holstein cross (HX), Indigenous cattle (IC) and Red Chittagong Cattle (RCC) milk. Protein and casein (CN) composition and type, casein micellar size (CMS), naturally occurring peptides, free amino acids, fat, milk fat globule size (MFGS), fatty acid composition, carbohydrates, total and individual minerals were analyzed. These components are related to technological and nutritional properties of milk. Consequently, they are important for the dairy industry and in the animal feeding and breeding strategies. Considerable variation in most of the principal components of milk were observed among the animals. The milk of RCC and IC contained higher protein, CN, ${\beta}$-CN, whey protein, lactose, total mineral and P. They were more or less similar in most of the all other components. The B milk was found higher in CN number, in the content of ${\alpha}_{s2}-$, ${\kappa}$-CN and ${\beta}$-lactalbumin, free amino acids, unsaturated fatty acids, Ca and Ca:P. The B milk was also lower in ${\beta}$-lactoglobulin content and had the largest CMS and MFGS. Proportion of CN to whey protein was lower in HX milk and this milk was found higher in ${\beta}$-lactoglobulin and naturally occuring peptides. Considering the results obtained including the ratio of ${\alpha}_{s1}-$, ${\alpha}_{s2}-$, ${\beta}$- and ${\kappa}$-CN, B and RCC milk showed best data both from nutritional and technological aspects.

• Asian-Australasian Journal of Animal Sciences
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• 제14권3호
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• pp.351-357
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• 2001

The rapid formation of a cream line cannot be observed in raw goat's milk standing at a low temperature. Although the poor creaming ability of goat's milk has been considered to be due to the small size of milk fat globules and the lack of euglobulin capable of being adsorbed on milk fat globules, there is much left to study. The present work attempted to elucidate a factor for poor creaming ability of goat's milk. The creaming ability of the experimental milks reconstituted from creams and skim milks separated from cow's milk or goat's milk was measured by the volume of the cream layer and the fat content of bottom layer. The polypeptides composition of the P1 the fraction (i.e., the high molecular weight fraction eluted near the void volume obtained by the gel filtration of whey) and milk fat globule membrane prepared from both milks were compared. It was found that the promotion of creaming originated from goat's skim milk was lower than that from cow's skim milk. The P1 fraction in goat's skim milk was less than that in cow's skim milk. The polypeptide (M.W. $4.3{\times}10^4$), found in the P1 fraction of cow's milk was not found in the P1 fraction of goat's milk. It is suggested that the poor creaming ability of goat milk is caused mainly by the difference from cow milk in the amount and the composition of the P1 fraction.

• 한국식품과학회지
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• 제16권3호
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• pp.279-284
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• 1984

분유와 분유로 제조된 cheese의 미세구조(微細構造)가 전자 현미경(顯微鏡)에 의해서 관찰되었다. 동결건조 분유는 사과모양을 나타내었다. 동결건조 분유로 제조된 cheese는 전형적인 용융 cheese와 비교하여 표면의 구조가 비교적 편편하고 백색의 균일한 침적물을 나타내었다. 도입 분유 역시 동결건조 분유와 거의 유사한 모앙을 나타내었고, 도입분유로 제조된 cheese는 균일한 분산을 나타내나 표면이 약간 거칠고 caseins matrix와 침적물 사이에 공간이 있다. 시판 분유는 건조중 변성된 것으로 불규칙한 변성 응고물의 모양을 나타내었다. 시판분유로 제조된 cheese의 모양은 불규칙하고 작은 침적물과 세공성이 큰 것으로 나타나 분유의 열변성도는 cheese의 세공성을 증가시키는 것으로 보인다. 변성된 단백질은 변성되지 않은 단백질보다 polyphosphate에 의한 단백질 분산성이 덜 효과적인 것으로 보인다. 분유로 제조한 cheese의 내부구조에서 지방구막과 casein micelle이 전형적인 용융 cheese에 비해 아주 근접해있고 casein micelle이 아주 치밀한 양상을 나타내었다. 분유의 용융 기작도 전형 적인 cheese의 용융과는 다른 것으로 보인다.

• Journal of Dairy Science and Biotechnology
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• 제35권3호
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• pp.202-207
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• 2017

본 연구에서는 반응표면분석법을 활용하여 균질 조건, 저장 온도, 저장 기간 등이 유지방의 크림화와 상층부와 하층부의 지방 함량 변화 등에 대해 미치는 영향을 분석하고, 최적의 균질 효율을 갖는 조건들을 예측하고자 실시하였다. 반응표면분석법의 독립변수로는 균질압, 저장 온도, 저장 기간을 설정하였고, -1, 0, 1의 3수준으로 20개의 실험구를 설계하여 종속변수인 creaming, USPHS code, 상층부의 $D_{4,3}$, 하층부의 $D_{4,3}$에 대해 실험을 실시하였다. 반응표면분석과 회귀분석 결과, 균질한 우유의 실험 데이터와 RSM에 의해 예측된 값들간의 상관계수는 0.8 이상의 상관성을 보였다. 반응표면분석의 최적화 결과, $10^{\circ}C$에서 15일의 저장 기간 동안 3 mm 이하의 크림화를 유지하기 위해서는 14 MPa 이상의 균질압이 요구되고, $20^{\circ}C$에서 15일의 저장 기간 동안 3 mm 이하의 크림화를 유지하기 위해서는 17 MPa 이상의 균질압이 요구된다. $10^{\circ}C$에서 15일의 저장 기간 동안 USPHS code를 10% 미만으로 유지하기 위해서는 16.8 MPa의 균질압이 요구되며, $20^{\circ}C$에서 15일 동안의 저장 기간을 유지하기 위해서는 23.1 MPa의 균질압이 요구된다.