• Journal of Animal Science and Technology
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• 제46권1호
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• pp.91-96
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• 2004

유단백질에서 유래된 아미노산은 주로 L-이성체의 형태로 존재하나 일부 미생물 세포벽의 구성성분과 일부 항생물질내 D-amnio acid(DAA)가 존재하고 있는 것으로 보고 되고 있으며 이는 유제품의 품질저하와 연관된다. 따라서 이 연구는 품질저하와 연관된다. 따라서 이 연구는 내냉성미생물 P. fluorescens와 P. putida에 의한 DAA 생성에 관해 실험하였다. 상업용 혼합 유산균주인 ABT-C를 접종하여 발효시간대별로 free D-amino acid를 분석하였으며, 실험결과 전체적인 DAA 함량은 매우 낮은 수준이고, 특히 발효시간대별 변화가 크게 없어 유산균의 증식에 의한 DAA의 생성은 매우 미미한 것으로 나타났고, 또한 일부 L-amino acid의 경우 유산균의 생육에 이용되는데 DAA의 경우 발효시간대별 함량이 큰 변화가 없는 것으로 보아 유산균의 이용성 역시매우 낮은 것으로 생각된다. 원유에서 분리한 P. fluorescens와 P. putida를 접종하여 배양시간대별로 free D-amino acid를 분석하였으며 실험결과 두 처리구 모두 배양시간에 따라 DAA의 생성이 증가되는 경향을 나타내었으며, P. putida의 경우 P. fluorescens에 비해 D-Pro의 증가량이 상대적으로 높게 나타났으나 나머지 4종은 P. fluorescens에 의한 생성량이 더욱 높게 나타났고, 특히 유해성이 높은 것으로 보고된 D-Asp 및 D-Ala의 함량이 매우 높게 나타났다. 따라서 DAA는 내냉성미생물에 의한 품질저하 지표로서 이용가능성과 더불어 인체의 유해성에 대한 위험성을 배제하는 차원에서도 매우 중요하게 인식되어야 할 것으로 사료된다

• Asian-Australasian Journal of Animal Sciences
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• 제28권12호
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• pp.1774-1783
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• 2015

Milk lysozyme is the ubiquitous enzyme in milk of mammals. In this study, the cDNA sequence of a new chicken-type (c-type) milk lysozyme gene (YML), was cloned from yak mammary gland tissue. A 444 bp open reading frames, which encodes 148 amino acids (16.54 kDa) with a signal peptide of 18 amino acids, was sequenced. Further analysis indicated that the nucleic acid and amino acid sequences identities between yak and cow milk lysozyme were 89.04% and 80.41%, respectively. Recombinant yak milk lysozyme (rYML) was produced by Escherichia coli BL21 and Pichia pastoris X33. The highest lysozyme activity was detected for heterologous protein rYML5 (M = 1,864.24 U/mg, SD = 25.75) which was expressed in P. pastoris with expression vector $pPICZ{\alpha}A$ and it clearly inhibited growth of Staphylococcus aureus. Result of the YML gene expression using quantitative polymerase chain reaction showed that the YML gene was up-regulated to maximum at 30 day postpartum, that is, comparatively high YML can be found in initial milk production. The phylogenetic tree indicated that the amino acid sequence was similar to cow kidney lysozyme, which implied that the YML may have diverged from a different ancestor gene such as cow mammary glands. In our study, we suggest that YML be a new c-type lysozyme expressed in yak mammary glands that plays a role as host immunity.

• 한국식품영양학회지
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• 제9권4호
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• pp.529-535
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• 1996

This study was performed to investigate some quality characteristics of 새려 prepared from soybean milk and various seaweed(Undaria pinnatifida, Laminaria japonica, Porpyra tenera, Enteromorpha sp., Codium sp.) pulps in the ration of 9:1(v:v) with 20% MgCl2. The yields of tofu containing Undaria pinnatifida, Laminaria japonica, or Enteromorpha sp. increased but porphyra tenera, Codium sp. decreased in comparison with tofu prepared from whole soybean milk. The protein content of tofu containing Undaria pinnatifida, Laminaria japonica, Porphyra tenera, or Codium sp. increased but Enteromprpha sp. decreased in comparison with the tofu prepared from whole soybean milk. The content of Ca in Undaria pinnatifida, Porphyra tenera added tofu was higher than that of the tofu prepared from whole soybean milk or other seaweeds added tofu. In sensory evaluation the texture, color, taste of tofu were favored with the addition of sea mustard(Undaria pinnatifida) pulp than that of the tofu prepared from whole soybean milk or tofu prepared other seaweed. Tofu prepared was possible with adding 0.5~1.5% sea mustard to soybean milk but the feasible added amount level was 1% of sea mustard. The yields, protein Ca, and K content of tofu were increased by the more adding amount of sea mustard tan tat of the tofu prepared from whole soybean milk. The hardness values of 1% sea mustard added tofu were decreased than that of the tofu prepared from whole soybean milk ; on the other hand, elasticity, cohensiveness, gumminess and brittleness of tofu with sea mustard increased. The L and a values of tofu were lower and b values were higher with the addition of 1% sea mustard. The content of histidine, tyrosine, leusine, and phenylalanine were decreased but the other amino acid were increased in tofu prepared from 1% sea mustard pulp added to soybean milk. The saturated fatty acid and monoene fatty acid content of tofu were increased and C18:2, C18:3(${\gamma}$), C18:3, C20:5 of polyene fatty acid were slightly decreased in tofu prepared from 1% sea mustard pulp added to soybean milk.

• 한국식품영양과학회지
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• 제22권6호
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• pp.815-822
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• 1993

This experiment was carried out to determine the separation condition of 1-dimethylaminonaphthalene-5-sulfony(Dansyl) derivatives of amino acids by reverse-phase high performance liquid chromatography with Nova-Pak C18 column. Determined solvent system was solvent A(200mA phosphate buffer pH 6.8 15%, acetonitrile 11%, water 74%) and solvent B(acetonitrile 65%, methanol 28%, water 7%). Linear gradient of solvent B was applied from 12% to 80% for 50min. Complete separation of 20 amino acids including asparagine and glutamine which constitute protein was achieved within 50min. As the detection limit was the range of picomole, the resolution power was excellent. Reproducibility of the retention time was less than mean $\pm$0.05min. According to the above optimum chromatographic conditions, the amino acid composition of some food and human blood was examined. The most affluent amino acid was alanine in human blood, aspartic acid and glutamic acid in soy sauce, alanine and threonine in soy milk and proline in milk and yoghurt.

• 한국식품영양과학회지
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• 제23권5호
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• pp.837-844
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• 1994

In order to making the good quality soybean cheese, it is prepared byover growing cow's milk added soybean curd with Actinomucor elegans and the nold-overgrown curd soked in salt-brine/ethanol mixture. The physicochemical changes and sensory evaluation were investigated during the aging period. Crude protein, carbohydrate, crude fat ash contents of the pehtze were increased by elapsing the fermentation time, whereas moisture's decreased . Amino-N and ammonia -N contents of cow's milk added pehtze and soybean phetze were increased 17.25%, 7.23% and 16.16%, 8.42% respectively. Total nitrogen content of the pehtze was decreased by elaping the aging time but soaking solution's increased. Free amino acid content of soybean cheese was increased as a result of the proteolytic action of molds. As a result, sulfur containing amino acid such as methionine and cysteine of the cow's milk added soybean cheese were enriched 1.3 times more than the soybean cheese. Flavor, taste and texture of the cow's milk added soybean cheese were higher than soybean cheese.

• Journal of Animal Science and Technology
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• 제64권1호
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• pp.110-122
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• 2022

The reduction of milk yield caused by heat stress in summer is the main condition restricting the economic benefits of dairy farms. To examine the impact of hyperthermia on bovine mammary epithelial (MAC-T) cells, we incubated the MAC-T cells at thermal-neutral (37℃, CON group) and hyperthermic (42℃, HS group) temperatures for 6 h. Subsequently, the cell viability and apoptotic rate of MAC-T cells, apoptosis-related genes expression, casein and amino acid transporter genes, and the expression of the apoptosis-related proteins were examined. Compared with the CON group, hyperthermia significantly decreased the cell viability (p < 0.05) and elevated the apoptotic rate (p < 0.05) of MAC-T cells. Moreover, the expression of heat shock protein (HSP)70, HSP90B1, Bcl-2-associated X protein (BAX), Caspase-9, and Caspase-3 genes was upregulated (p < 0.05). The expression of HSP70 and BAX (pro-apoptotic) proteins was upregulated (p < 0.05) while that of B-cell lymphoma (BCL)2 (antiapoptotic) protein was downregulated (p < 0.05) by hyperthermia. Decreased mRNA expression of mechanistic target of rapamycin (mTOR) signaling pathway-related genes, amino acid transporter genes (SLC7A5, SLC38A3, SLC38A2, and SLC38A9), and casein genes (CSNS1, CSN2, and CSN3) was found in the heat stress (HS) group (p < 0.05) in contrast with the CON group. These findings illustrated that hyperthermia promoted cell apoptosis and reduced the transport of amino acids into cells, which inhibited the milk proteins synthesis in MAC-T cells.

• Journal of Dairy Science and Biotechnology
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• 제33권1호
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• pp.17-25
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• 2015

본 실험은 쌀겨를 발효식품에 이용하고자 상업용 균주인 Streptococcus thermophilus(ST-body1), Lactobacillus casei(LC-10)을 이용하여 발효유를 제조하고, 발효시간 경과에 따라 적정산도, 유산균수, 유기산 측정, 유리아미노산 측정, 관능검사를 측정하였다. ST-body1은 대조구와 처리구 모두 발효 3시간째에 급격하게 산도가 증가하였다. 하지만 LC-10은 산도의 증가폭이 크지 않아 24시간 발효를 하여도 산도가 0.5%를 넘지 못하였다. 균주의 생균수는 대조군과 실험군 모두 배양 24시간 동안 뚜렷한 경향 없이 $10^6{\sim}10^9CFU/mL$ 사이로 존재하였다. 유기산 및 유리아미노산 측정 결과, ST-body1 생장 및 생육에는 glutamic acid가 LC-10 생장 및 생육에는 aspartic acid가 밀접한 관계를 보였으며, LC-10은 발효 시 methionine이 20~30시간 경에 감소하다가 증가하는 것으로 보아 methionine을 발효 시 이용하고, 재생산하는 것으로 추측된다. 관능검사 결과, 선호도는 ST-body1이 미강의 존재 유무에 관계없이 우수하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제29권7호
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• pp.1022-1028
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• 2016

Milk composition is an imperative aspect which influences the quality of dairy products. The objective of study was to compare the chemical composition, nitrogen fractions and amino acids profile of milk from buffalo, cow, sheep, goat, and camel. Sheep milk was found to be highest in fat ($6.82%{\pm}0.04%$), solid-not-fat ($11.24%{\pm}0.02%$), total solids ($18.05%{\pm}0.05%$), protein ($5.15%{\pm}0.06%$) and casein ($3.87%{\pm}0.04%$) contents followed by buffalo milk. Maximum whey proteins were observed in camel milk ($0.80%{\pm}0.03%$), buffalo ($0.68%{\pm}0.02%$) and sheep ($0.66%{\pm}0.02%$) milk. The non-protein-nitrogen contents varied from 0.33% to 0.62% among different milk species. The highest r-values were recorded for correlations between crude protein and casein in buffalo (r = 0.82), cow (r = 0.88), sheep (r = 0.86) and goat milk (r = 0.98). The caseins and whey proteins were also positively correlated with true proteins in all milk species. A favorable balance of branched-chain amino acids; leucine, isoleucine, and valine were found both in casein and whey proteins. Leucine content was highest in cow ($108{\pm}2.3mg/g$), camel ($96{\pm}2.2mg/g$) and buffalo ($90{\pm}2.4mg/g$) milk caseins. Maximum concentrations of isoleucine, phenylalanine, and histidine were noticed in goat milk caseins. Glutamic acid and proline were dominant among non-essential amino acids. Conclusively, current exploration is important for milk processors to design nutritious and consistent quality end products.

• 한국식품영양과학회지
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• 제22권4호
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• pp.437-442
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• 1993

두유에 우유를 각각 10, 20, 30, 40, 50%(v/v) 첨가하고 두부를 제조하여 일반성분의 함량변화, 수율과 pH 변화, 관능검사, 견고성, 무기이온 함량의 변화 및 amino acid 조성을 조사 비교하였다. 수분함량은 우유첨가로 다소 감소하는 경향을, 당, 지방, 단백질, 회분의 함량은 우유의 첨가량이 증가함에 따라 증가하였고 pH 값은 우유의 첨가량이 증가함에 따라서 높아졌다. 두부의 무게와 용적은 우유의 첨가량에 비례적으로 증가하였다. 굳기는 우유 첨가량에 비례하여 증가하였으며 금속이온의 함량변화는 우유의 첨가량이 증가함에 따라 비례적으로 $Ca^{＋＋}$, $K^{＋}$, $Na^{＋}$는 증가한데 반하여 $Mg^{＋＋}$, Fe$^{＋＋}$는 감소하였다. 관능평가에서 색감은 우유의 첨가량이 증가할수록 식감과 냄새 그리고 맛은 30~40%의 우유 첨가에서 평점이 높았다. 함황아미노산의 함량은 우유 10, 20, 30, 40, 50% (v/v) 합한 경우 각 대조구(0%)에 대하여 1.51, 1.58, 1.67, 1.85, 1.95배 증가되었다. 즉 두유에 우유를 첨가하여 두부를 만들 경우 기존 두부의 품질에 큰 변화없이 두부의 단백질이 강화되었고 부수적으로 맛도 구수하게 향상되는 결과를 얻었다.

• Asian-Australasian Journal of Animal Sciences
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• 제20권2호
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• pp.273-282
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• 2007

This study was carried out to compare the changes of nutrients, sensory and chemical properties of freeze-concentrated and evaporated milks during storage. For pasteurization, the freeze-concentrated milk containing 27% of total solid was treated with 150 rpm ozone for 5 min, and 99% of microflora was eliminated. Also, the activities of protease and lipase decreased 93.31% and 96.15%, respectively, and phosphatase showed negative activity. Total bacteria count was maintained below$2.0{\times}10^4$CFU/ml. During storage, TBA absorbance was lower in freeze-concentrated milk than that in the evaporated milk. The production of short-chain free fatty acids and free amino acids increased proportionally to the storage period in both samples. While the short-chain free fatty acid production was lower in the freeze-concentrated milk compared with that in the evaporated milk, the production of individual free amino acid was similar in both samples. In sensory evaluation, cooked flavor and color were much lower in the freeze-concentrated milk than that in the evaporated milk. Overall acceptability score was higher in the freeze-concentrated than the evaporated milk. Based on above results, ozone treatment for the freeze-concentrated milk pasteurization was positive at the elimination of microflora and enzyme inactivation. During storage, the freeze-concentrated sample minimized the change of color and TBA absorbance, the production of short-chain free fatty acid and vitamins than the evaporated milk. Therefore, the freeze-concentrated milk process in the present study resulted in the positive effect in minimizing nutrient loss and keeping quality of milk during storage.