• The Science & Technology
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• v.30 no.12 s.343
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• pp.32-34
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• 1997

내가 유학하고 있던 동경대학 발효학연구실에서의 일이다. 석사과정 때는 '미생물에 의한 비타민 A생산'이란 연구과제로, 또 박사과정에선 '치즈를 만드는데 필요한 송아지 rennet를 미생물이 생산하는 효소로 대치하는 연구'로 실험에 몰두했지만 거듭된 실패의 연속으로 나는 많은 어려움을 겪었다. 그러나 끈질긴 도전으로 획기적인 연구결과를 얻게 되어 그 연구개발경험을 소개한다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.6
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• pp.1117-1124
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• 1998

Chymosin was purified from commercial rennet with DEAE Sepharose CL 6B and immobilized on CeliteTM using glutaraldehyde. Whole casein from fresh raw milk was hydrolyzed by immobilized chymosin and total CMP was isolated by trichloroacetic acid(TCA) and ultrafiltration, and characterized. The amount of chymosin purified from 15g commercial rennet by DEAE Sepharose CL 6B was 0.16g and 18mg of chymosin was immobilized on 1g of CeliteTM by 5% glutaraldehyde. Immobilized chy mosin hydrolyzed most of casein on whole casein within 2 hours to leave para casein and casei nomacropeptide(CMP). The total CMP isolated from 10g of whole casein hydrolyzate by TCA and ultrafiltration was 0.4g and 0.1g, respectively. Results of electrophoresis, amount of sialic acid, com position of amino acid and ratio of A280 to A214 showed that total CMP by TCA was purer and had more CMP without carbohydrate than one by ultrafiltration. CMP isolated from total CMP by 12% TCA precipitation was 50% of total CMP and most of caseinoglycopeptide(CGP) was removed from total CMP, indicating less amount of sialic acid in CMP than in total CMP.

• Korean Journal of Food Science and Technology
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• v.10 no.2
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• pp.231-236
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• 1978

It has been investigated that preparation of cheese-like product from defatted soybean milk and changes during 6 weeks' ripening. Obtained results were as follows: 1. Defatted soybean milk was fermented at $37^{\circ}C$ for 4 hours with Streptococcus lactis YUFE L-4 without addition of any other carbon sources. 2. Optimum concentration of coagulant such as $MgCl_2{\cdot}6H_2O$ and $CaCl_2$ were 0.0125M and 0.0375M, respectively. 3. Coagulating time for 30 minutes was sufficient to make curd. 4. Optimal reaction temperature for coagulating were $50^{\circ}C$. 5. After 6 weeks' ripening, moisture content was approximately $62{\sim}63%$. Water and 10%-TCA soluble nitrogen contents of soybean cheese with Asp. saitoi protease were higher than those of Mucor rennet. Water soluble nitrogen content of Asp. saitoi protease cheese was 50.5% and 10%-TCA soluble nitrogen was 27.5%.

• The Microorganisms and Industry
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• v.20 no.3
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• pp.23-25
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• 1994

효소가 산업적 의미를 갖게 되는 시작은 1884년 네덜란드의 Christian Hansen이 송아지의 위에서 rennet를 추출하여 사용함에 따라서 시작되었고, 이후, 일본인 Takamine가 1894년 Koji 배양법에 의해서 곰팡이 Amylase를 상업화하면서 미생물을 이용한 효소생산이 성공되어서 대량생산이 가능하게 되었다. 이후, 20세기에 들면서 독일의 Otto Rohm에 의해서 피혁가공 및 세제에의효소이용, 1911년 미국의 Leo Waltersten이 효소를 이용한 Chill-proofing beer의 개발 등으로 효소의 이용용도가 식품에서 환경공업으로 확대되었고 효소의 산업적 수요가 확대됨에 따라서 이에 따른 막대한 연구투자가 이루어져 비로소 효소산업이 태동하게 되었다.

• 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.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.22 no.6
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• pp.391-396
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• 1990

Changes in electric resistance was measured to carry out the kinetic analysis of milk gellation upon addition of rennet. Using pasteurized milk and commercial rennin, kinetic properties were investigated during milk gellation in terms of initial hydrolysis and coagulation steps. Specially designed reactor with two platinum electrodes was used throughout the experiments. As a function of either milk concentrations or reaction temperatures, gel time exhibited directly proportional relations: on the contrary, gel time was inversely pro-portional to enzyme concentration. Activation energies for enzymatic degradation and cogulation were 16.3, 4.6 and 34, 8.6 Kcal/mol, repectively. This simple analytical method proved to be very effective to characterize the mechanism of milk gellation. Moreover, unlike other methods, this method reguired simple apparatus and short time of analysis.

• Journal of Dairy Science and Biotechnology
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• v.30 no.1
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• pp.55-67
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• 2012

We compared the general composition of Mozzarella cheese manufactured by the traditional method and by an ultrafiltration technique. The comparison of the general components between raw milk and the retentate of ultrafiltration (CF 2 and CF 3) demonstrated the following. The fat, protein, and non-fat solid contents of the retentate were higher than those of raw milk, but the lactose content was lower. The effect of 3 factors-fat content (0.5% and 3%), bacterial populations (30,000 CFU/mL and 100,000 CFU/mL), and ratio of added starter and rennet (50, 65, or 80)-on Mozzarella cheese made by the traditional method and made using the retentate of ultrafiltration (CF 2 and CF 3) were compared. Total solids (TS), fat, lactose, total nitrogen (TN), water soluble nitrogen (WSN), non-protein nitrogen (NPN), and salt (NaCl) were affected by fat content, bacterial population, and the ratio of starter and rennet added, but the ash content was not affected. During storage at $4^{\circ}C$ over a period of 3 months, the TS, WSN, NPN, and NaCl contents increased significantly (p<0.05), but fat, lactose, and TN contents decreased significantly (p<0.05), while ash contents remained constant. In whey, the protein, lactose, and solids not fat contents were higher in cheese made from ultrafiltration retentate than in traditional Mozzarella cheese. These results indicate that ultrafiltration can be applied to producing several Mozzarella-type cheeses in order to meet consumer needs.

• Journal of Dairy Science and Biotechnology
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• v.30 no.1
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• pp.1-10
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• 2012

The objective of this study was to evaluate the rheology and sensory properties of Mozzarella cheese manufactured by the traditional method and by an ultrafiltration technique and to attempt to develop a new type of Mozzarella cheese. We noted 3 observations. (1) The initial pH observed for raw milk and retentate of ultrafiltration (CF 2 and CF 3) did not vary much. However, there was a significant difference in the pH at stretching. The initial TAwas significantly different between the raw milk and retentate obtained by ultrafiltration (CF 2 and CF 3). However, no differences were observed in TA at stretching. (2) The predicted yield (Y50), adjusted to 50% total solids (TS), was affected by the concentration factor, fat content, and addition of starter and rennet. The Y50 increased with the concentration factor. 3) Hardness, elasticity, cohesiveness, and brittleness were affected by fat content, and addition of starter and rennet. The hardness, elasticity, and brittleness of Mozzarella cheese made from the retentate of ultrafiltration (CF 2 and CF 3) were higher than in Mozarella cheese made by the traditional method; however, the cohesiveness decreased during storage at $4^{\circ}C$ over a period of 3 months. (4) Flavor, body texture, appearance, color, and firmness decreased with bacterial count, fat content, and addition of starter and rennet. The results of the sensory evaluation of the Mozzarella cheese made from the retentate of ultrafiltration (CF 2 and CF 3) changed during storage at $4^{\circ}C$ over a 3-month period.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.10
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• pp.1319-1324
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• 2010

The objectives of this study were to compare the effectiveness of different indicators of mammary inflammation in buffalo and to evaluate the association of the indicators with buffalo milk yield, composition, and rennet coagulation properties. This study was carried out at four buffalo farms in central Italy using a total of 50 lactating buffalo. Milk from each buffalo was tested at the beginning, middle, and end of lactation. To evaluate the relationship between mastitis markers and milk components, three classes were defined for each of the following markers: total somatic cell count (TSCC), differential somatic cell count (DSCC), and bacteriological results The regression coefficient for the reference method and the alternative method of determining TSCC was 0.81, indicating that the method routinely used to analyze buffalo milk consistently underestimated actual TSCC. The milk samples positive for udder-specific bacteria also had higher TSCC values than the samples that were negative for bacteria ($872{\times}10^3$/ml vs. $191{\times}10^3$/ml). In samples that were positive for udder-specific bacteria, polymorphonuclear leukocytes (PMN) made up greater than 50% of the cells. Moreover, only 1% of the samples in the lowest TSCC class were positive for bacteria. The correlation between TSCC and PMN was stronger (0.70), and PMN values in buffalo milk increased significantly when the TSCC class changed from low (38%) to medium and high (56% and 64%). Milk yield was negatively related to TSCC. Significant changes in lactose (4.87%, 4.80% and 4.64%) and chloride content (0.650 mg/ml, 0.862 mg/ml and 0.882 mg/ml) were also observed with increasing TSCC values. Higher TSCC was associated with impaired rennet coagulation properties: the clotting time increased, while the curd firming time ($p{\leq}0.05$) and firmness decreased. We concluded that in buffalo as in dairy cows, TSCC is a valid indicator of udder inflammation; we also confirmed that a value of $ 200{\times}10^3 cells/ml should be used as the threshold value for early identification of an animal affected by subclinical mastitis. In addition to its association with significantly decreased milk yield, a TSCC value above this threshold value was associated with changes in milk composition and coagulating properties.

• Food Science of Animal Resources
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• v.38 no.1
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• pp.52-63
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• 2018

Cheese consumption has been gradually increased in China. However, both the manufacturing process of cheese and the utilization of its main by-product were not well developed. Based on the sensory evaluation, Box-Behnken Design (BBD) was performed in the present study to optimize the cheese processing, which was proved more suitable for Chinese. The optimal parameters were: rennet 0.052 g/L, start culture 0.025 g/L and $CaCl_2$ 0.1 g/L. The composition analysis of fresh bovine milk and whey showed that whey contained most of the soluble nutrients of milk, which indicated that whey was a potential resource of cyclic adenosine-3', 5'-monophosphate (cAMP). Thus, the cAMP was isolated from whey, the results of high-performance liquid chromatography (HPLC) analysis showed that the macroporous adsorption resins (MAR) D290 could increase the concentration of cAMP from $0.058{\mu}mol/mL$ to $0.095{\mu}mol/mL$. We firstly purified the cAMP from the whey, which could become a new source of cAMP.