• Journal of Dairy Science and Biotechnology
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• v.40 no.4
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• pp.151-162
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• 2022

Although many developed countries (USA, Canada, and several EU countries) allow raw milk cheese to be aged more than 60 days, these countries have strict standards for the aging conditions, such as temperature, of raw milk cheese. Spiking experiments were conducted with Camembert cheese made from raw milk, to assess the microbiological safety of raw milk cheese aged for more than 60 days. We spiked Escherichia coli O157:H7 into raw milk with different inoculation levels (high, medium, and low). Camembert cheese was prepared from the inoculated raw milk, then aged in an incubator for up to 9 weeks (63 days). There were no significant differences in pH and water activity (aW) between uninoculated cheese and cheese samples inoculated with E. coli O157:H7 (p<0.05). The pH and aWof the Camembert cheese decreased throughout the storage period. In conclusion, E. coli O157:H7 did not affect the pH and aW of the cheese samples. Cell counts were conducted every week using the agar-plating method. Inoculated cells were completely eliminated, especially in Camembert cheese, after 60 days, and the reduction rate of cells was much faster in Camembert cheese.

• Journal of Dairy Science and Biotechnology
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• v.40 no.4
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• pp.163-172
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• 2022

Although the USA, Canada, and several EU countries allow raw milk cheese to be aged more than 60 days, these countries have strict standards for its aging conditions, such as temperature. Many developed countries have employed standards of identity which effectively prevent the manufacture and sale, of cheese made from unpasteurized milk (i.e., raw milk) in interstate commerce, unless such cheese has been aged for a minimum of 60 days. The microbiological safety of raw milk Camembert cheese, aged for more than 60 days, was evaluated using spiking experiments. We spiked Listeria monocytogenes into raw milk with different inoculation levels (high, medium and low). Camembert cheese was prepared from the inoculated raw milk, then aged in an incubator for up to 9 weeks (63 days). The number of cells was determined every week using the agar-plating method. Inoculated cells were completely eliminated, especially in Camembert cheese, after 60 days, and the reduction rate of cells was much faster in Camembert cheese. There were no significant differences in pH and water activity (aW) between the uninoculated cheese and the cheese samples in which Listeria monocytogenes was inoculated (p<0.05). The pH and aW of the Camembert cheese decreased throughout the storage period. In conclusion, the pathogenic bacteria used in this study did not affect the pH and aW of the Camembert cheese samples.

• Journal of Dairy Science and Biotechnology
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• v.24 no.2
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• pp.11-20
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• 2006

Korea dairy industry has a long and chronic problems to consume raw milk , those are surplus milk and decline the market milk consumption continued about 10 years. This study was aim to propose and to find the solution for dairy industry problems. After WTO system, with the importation of dairy products, domestic milk production has fell into the situation of excess supply and huge inventory of dried milk, the milk powder stocks have increased since 2002. That made a chronic decline milk consumption in Korea. The core of chronic problem of Korea dairy industry is the decreasing in market milk consumption. If they have a settlement of any other way using their raw milk to process and consumption to market milk, there will be a solution to solve the chronic problems in this situation. Especially, that will be a development of small farm scale natural cheese production and consume. This may be lead a situation of increase the raw milk consumption, because natural cheese making needs much of raw milk more than market milk. But there are very low technical level of farmers cheese making status, so they need a cheese making educational program for their commercial level of cheese products. Under these situation, there are needed a way out of educational system for the dairy farmers to obtain the high level of cheese making technology from the trustable and scientific organization. The natural cheese making technique of dairy farmers should be accumulated to get the consumers' solid recognition of high quality of natural cheese as LOHAS(Lifestyle Of Health And Sustainability) foods.

• Journal of Dairy Science and Biotechnology
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• v.31 no.1
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• pp.21-33
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• 2013

The purpose of this study was to improve the production of Mozzarella cheese analogues manufactured using mixtures of soy milk and concentrated raw milk by performing ultrafiltration (UF) and to assess the quality of these cheeses during a 30-day storage period at $4^{\circ}C$, relative to that of Mozzarella cheese manufactured with the traditional method. The solid consistency of Mozzarella cheese analogue prepared from milk mixtures was lower than that of cheese manufactured from raw milk or soy milk and increased during storage, which is considered to be the result of decreasing water levels, as well as with increasing soy milk concentrations. In the Mozzarella cheese analogue generated using the milk mixtures, the fat content decreased with increase in the soy milk concentration, while it decreased during the storage period. Lactose levels were lowest in cheese composed of soy milk or raw milk and processed by UF, and decreased during storage in cheese produced using milk mixtures. In milk mixtures containing soy milk, the protein concentration increased with increasing amounts of raw milk and did not change during the storage period. The water-soluble nitrogen compound level was similar between cheeses and increased only slightly during storage. The amount of non-protein nitrogen compounds was higher in the cheese analogue than in the control cheese and tended to increase during storage. Analysis of the physicochemical traits of the Mozzarella cheese analogue yielded the following results: During storage, titratable acidity levels increased while pH tended to decrease. After analysis using electropherograms, it was classified as ${\alpha}$-, ${\beta}$-, or ${\kappa}$-casein. The results of rheometry tests showed that in the Mozzarella cheese analogue prepared from milk mixtures, with raw milk concentrated by UF, increases in concentration rate lead to lowered hardness, elasticity, cohesiveness, and brittleness. When cheese was produced from milk mixtures and concentrated by UF, meltability increased as the concentration rate increased, although to an extent that was less than that observed for the control cheese, and tended to increase during storage. Sensory evaluation showed that the analogue cheese was much better than the control cheese in terms of formation, appearance, and flavor.

• Journal of Dairy Science and Biotechnology
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• v.37 no.1
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• pp.33-39
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• 2019

The purpose of this study was to explore the microbiological safety of various cheeses made from raw milk currently imported and sold in Korea. A total of 12 cheeses were considered for the study - 4 kinds of imported cheese made from raw milk, 4 kinds of imported cheese made from pasteurized milk, and 4 kinds of domestic cheese made from pasteurized milk, and aerobic count, presence of E. coli, Salmonella spp., and Listeria monocytogenes were investigated. Results from this study showed that in the 12 different kinds of cheese tested, E. coli, Salmonella spp., and Listeria monocytogenes were negative. Therefore, the sanitary conditions of imported cheese made from raw milk, imported cheese made from pasteurized milk, and domestic cheese made from pasteurized milk are considered safe. The mean aerobic count in the 12 types of tested cheese was below 4.0 log CFU/g. In conclusion, various cheeses produced from raw milk or pasteurized milk currently sold in Korea have been found to be hygienic and safe. In the future, raw milk cheeses produced and sold in Korea will require long-term research not only to ensure safety but also to produce new, high-quality products.

• Journal of Dairy Science and Biotechnology
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• v.31 no.1
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• pp.9-20
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• 2013

The study was conducted to evaluate the feasibility of Mozzarella cheese analogue generation by using a mixture of soy milk and raw milk and to compare the quality of the resultant cheese with that of Mozzarella cheese manufactured using the traditional method. The mixtures showed increase in protein and decrease in lactose and SNF in a dose-dependent manner with the addition of soy milk. The Mozzarella cheese analogue had lower total solids content than the control cheese product, while the fat content was similar between both. The analogue cheese had lower ash content than the traditionally prepared cheese; the content was proportional to the amount of soy milk in the mixture. Higher soy milk quantities within mixtures also resulted in proportionally higher levels of fat content within analogue cheese. Water-soluble nitrogen content was lower in the analogue cheese than in the control cheese. While the WSN level increased in the control cheese, it was almost constant in the analogue cheese. The control cheese had much higher actual and predicted yield than the analogue cheese, while the analogue cheese had a higher stability level. The control cheese had a higher transfer rate than the analogue cheese, with the exception of lactose. Electrophoresis analysis showed bands for Mozzarella cheese analogues that were present in addition to the normal ${\alpha}$-casein and ${\beta}$-casein bands. Physical characteristic analysis showed that hardness was affected by the addition of soy milk to cheese, while cohesiveness and brittleness were affected by the addition of raw milk, and elasticity was barely affected by milk composition. The meltability of the control cheese was higher than that of the analogue cheese and increased during 30 days of storage at $4^{\circ}C$. Browning, oiling-off, and stretching characteristics were almost identical between the 2 types of cheeses. Sensory evaluation findings showed that the control cheese had much better body texture, appearance, and flavor than the analogue cheese.

• Journal of Dairy Science and Biotechnology
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• v.36 no.2
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• pp.95-105
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• 2018

Since 2018, the Korean government has permitted the production and sale of any cheese made from raw milk and aged for at least 60 days. The present study aimed to investigate the sensory characteristics of various types of Gouda cheese produced from raw milk during 60-day aging. The average pH of the raw milk used in this experiment was $6.7{\pm}0.4$, similar to that of the sterilized milk. The pH of raw-milk Gouda cheese was $5.2{\pm}0.5$ a day after the 60-day aging period, wherein the pH was $5.5{\pm}0.3$. In total, 5 samples were used for sensory evaluation in this experiment: Cheeses 1~5. With respect to flavor, Cheeses 1 and 5 received the highest and lowest scores, respectively. Raw-milk Gouda cheese produced using Salmonella spp.-contaminated raw milk was not greatly influenced by flavor; however, it had a negative effect on its appearance. In the future, it is imperative to carry out sensory evaluation of cheese produced with raw milk contaminated with various food-contaminating bacteria.

• Food Science of Animal Resources
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• v.35 no.2
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• pp.205-210
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• 2015

The objective of this study was to develop yogurt-cheese using cow’s milk, ultrafiltrated cow’s milk, and soy milk. The addition of soy milk and ultrafiltrated milk increased the amount of protein in the yogurt-cheese. Yogurt-cheeses were made using cheese base using 10% and 20% soy milk with raw and ultrafiltrated cow’s milk, and stored at 4°C during 2 wk. The yield of yogurt-cheeses made with added soy milk was decreased and the cutting point was delayed compared to yogurt-cheese made without soy milk. Yogurt-cheese made using ultrafiltrated cow’s milk showed the highest yield. However, yogurt-cheese made with added soy milk had higher protein content and titratable acidity than yogurt-cheese made using raw and ultrafiltrated cow’s milk. Fat and lactose contents in the yogurt-cheese made with added soy milk were lower. Yogurt-cheeses made with added soy milk contained several soy protein bands corresponding to the sizes of α₂-, β-, and κ-casein band. Yogurt-cheese made with added soy milk had similar elasticity to yogurt-cheese made without soy milk but had lower cohesiveness. There was no significant difference in the number of lactic acid bacteria in the different cheeses, as all had over 8.0 Log CFU/g. Considering these data and the fact that proteins and fats of vegetable origin with high biological value were observed as well as unsaturated fats, yogurt-cheese made with added soy milk can be considered to be a functional food.

• Food Science of Animal Resources
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• v.39 no.4
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• pp.585-600
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• 2019

Gouda cheese, one of most popular cheeses in the Korea, has been produced from only pasteurized milk in Korean dairy farms. Recently, it has become legally possible to produce ripened cheese manufactured with raw milk in Korea. In the present study, we investigated the physico-chemical and microbiological characteristics of Gouda cheese manufactured with raw (R-GC) or pasteurized milk (P-GC) during manufacturing and ripening. Particularly, this study characterized the bacterial community structure of two cheese types, which are produced without pasteurization during ripening based on next generation sequencing of 16S rRNA gene amplicons. During ripening, protein and fat content increased slightly, whereas moisture content decreased in both P-GC and R-GC. At the 6 wk of ripening, R-GC became softer and smoother and hence, the values of hardness and gumminess, chewiness in R-GC was lower than that of P-GC. Metagenomic analysis revealed that the bacterial genera used a starter cultures, namely Lactococcus and Leuconostoc were predominant in both P-GC and R-GC. Moreover, in R-GC, the proportion of coliform bacteria such as Escherichia, Leclercia, Raoultella, and Pseudomonas were detected initially but not during ripening. Taken together, our finding indicates the potential of manufacturing with Gouda cheese from raw milk and the benefits of next generation sequencing for microbial community composition during cheese ripening.

• Microbiology and Biotechnology Letters
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• v.22 no.1
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• pp.99-105
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• 1994

In this study we compared traditional cheesemaking process with the process utilizing ultrafiltration(UF) system. The whole milk retentates were prepared by ultrafiltration to volume concentration ratio(VCR) of 2.00:1, 2.25:1 and 2.50:1. Along with the untreated whole milk, there were studies in terms of the change of pH, titratable acidity and Soxhlet-Henkel($\circ $SH) value by mesophilic lactic starter and curd formation by rennet during Gouda cheese manufacture. Due to the increase of buffering effect titratable acidity and $\circ $SH value increased with the higher concentration ratio. When inoculated with the same volume of mesophilic lactic starter, less pH change occurred in UF retentates than in control milk. When added 0.0025% rennet, UF retentates coagulated 16~ 17 minutes ealier then the control milk. Gouda cheese yield from raw milk and UF retentates was 12.5~13.1% equally, but yield efficiency of UF retentate cheese was slightly higher than that of the raw milk cheese. Quantity of whey from retentate cheese was inversely related to VCR. But whey from retentate cheese contained higher percentage of amjor components than that from control milk cheese. In early ripening, the concentrations of lactose and soluble nitrogen compound were higher in retentate cheeses. Lactose content of control milk cheese was 3.49% and that of 2.00:1. 2.25:1, 2.50:1 VCR retentate was 3.77%, 4.89%, 7.03%, respectively. Thus, the more concentrated cheese contained a higher amount of lactose and all the lactose was hyerolyzed durion 35-day ripenion period. Soluble nitrogen compound of control milk cheese was 1.22% and that of UF cheeses was 1.82~2.06%. After 20-day ripening, soluble nitrogen compound increased starply in UF cheese.