• Journal of Dairy Science and Biotechnology
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• v.32 no.2
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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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• v.30 no.12
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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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• v.33 no.3
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• pp.209-214
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• 2015

This study was carried out to investigate the effects of different milking systems (AMS, automatic milking system and CMS, conventional milking system) and of supplemental fat feeding on milk composition and milk fat characteristics. The composition, MFG (milk fat globule) size, fatty acids (FAs), and free fatty acids (FFAs) of the milk from 4 AMS and 4 CMS dairy farms were analyzed on the basis of the milking system and feeding of protected fat. The milking system did not affect milk composition, MFG size, and milk FAs, but FFA content of AMS milk were significantly higher than that of CMS milk. Feeding of protected fat resulted in the production of milk much higher in LCFAs (long chain FAs); however, the milk composition was not affected by fat supplementation. Cows administered protected fat supplements produced milk containing MFGs with a large average diameter.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.6
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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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• v.14 no.3
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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.

• Korean Journal of Food Science and Technology
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• v.16 no.3
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• pp.279-284
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• 1984

Microstructure of milk powder and cheese made from milk powder were observed by electron microscope. Freeze dried milk powder showed apple-like appearance. The cheese made from freeze dried milk powder had relatively flat surface and homogenous deposit in compare with classical processed cheese. Imported milk powder also indicated similar surface as well as freeze dried milk powder, however, the cheese made from imported milk powder had somewhat coarse surface structures with the spaces between casein matrix and deposit. Commericial milk powder showed irregular shape in size and coagulum which were possibly denatured in the course of drying. The cheese made from commercial powder indicted irregular and small deposit and porous structure. The porousity of the cheese seemed to be influenced by the degree of heat treatment. Denatured protein would be less dispersive than native in presence of polyphosphates. Fat globule and protein micelle of cheese made from skim milk powder get very adjacent to each other and showed compactness of micelles. It is thought that melting mechanism of skim milk powder was different from the melting of typical processed cheese.

• Journal of Dairy Science and Biotechnology
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• v.35 no.3
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• pp.202-207
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• 2017

The objective of this study was to analyze the effects of homogenization, storage temperature, and storage period on the creaming of milk fat and changes in fat contents in the upper and lower layers and to predict the conditions for optimal homogenization efficiency using response surface methodology (RSM). The homogenization pressure, storage temperature, and storage period were set as independent variables of RSM, and the dependent variables were creaming, US Public Health Service (USPHS) code, and volume weighted mean diameter ($D_{4,3}$) in the upper and lower layers. Based on the results of RSM and regression analysis, the correlation coefficient ($R^2$) between experimental data and predicted values by RSM for homogenized milk was estimated to be more than 0.8. The RSM analysis indicated that optimal homogenization pressures of 14 MPa or more and 17 MPa or more were required to maintain the creaming layer of 3 mm or less during the storage for 15 days at $10^{\circ}C$ and $20^{\circ}C$, respectively. To keep the USPHS code at less than 10% for 15 days at $10^{\circ}C$ and $20^{\circ}C$, milk should be homogenized with a pressure of 16.8 MPa or more and 17 MPa or more, respectively.