• Food Science of Animal Resources
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• v.42 no.1
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• pp.46-60
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• 2022

In this study, angiotensin-I-converting enzyme inhibitory (ACEI) activity was evaluated in fermented goat milk fermented by lactic acid bacteria (LAB) from fermented foods and breast milk. Furthermore, the potential for ACEI peptides was identified in fermented goat milk with the highest ACEI activity. The proteolytic specificity of LAB was also evaluated. The 2% isolate was inoculated into reconstituted goat milk (11%, w/v), then incubated at 37℃ until pH 4.6 was reached. The supernatant produced by centrifugation was analyzed for ACEI activity and total peptide. Viable cell counts of LAB and titratable acidity were also evaluated after fermentation. Peptide identification was carried out using nano liquid chromatography mass spectrometry (LC-MS/MS), and potential as an ACEI peptide was carried out based on a literature review. The result revealed that ACEI activity was produced in all samples (20.44%-60.33%). Fermented goat milk of Lc. lactis ssp. lactis BD17 produced the highest ACEI activity (60.33%; IC₅₀ 0.297±0.10 mg/mL) after 48 h incubation, viable cell counts >8 Log CFU/mL, and peptide content of 4.037±0.27/mL. A total of 261 peptides were released, predominantly derived from casein (93%). The proteolytic specificity of Lc. lactis ssp. lactis BD17 through cleavage on the amino acid tyrosine, leucine, glutamic acid, and proline. A total of 21 peptides were identified as ACEI peptides. This study showed that one of the isolates from fermented food, namely Lc. lactis ssp. lactis BD17, has the potential as a starter culture for the production of fermented goat milk which has functional properties as a source of antihypertensive peptides.

• Analytical Science and Technology
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• v.7 no.1
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• pp.53-64
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• 1994

After establishment of methodology for the separation and quantitation of optical isomer existed in food or biomaterial, the relationship between isomer and nutrient or biological sample was investigated. The optical isomers of standard amino acids and free amino acids were quantitized and the protein was assayed from the Korean bean, pasted bean, soy sauce, gochujang, powderd milk and cataract followed by hydrolysis and dervatization with TFA-IPA for GLC analysis with chirasil val column. Amino acids showing the racemization were alanine, aspartic acid, glutamic acid and phenyl alanine. The most convenient amino acid deducing age and biological activity was aspartic acid. Glutamic acid and phenyl alanine have shown poor resolution with less racemization. The ratio of d-form amino acids was 3~6% for home made pasted bean, about 3% for commerical pasted bean, 2~4% for soy sauce, about 1% for bean, 1~2% for cataract, 1.0~1.5% for powdered milk. The racemization during fermentation process was significant.

• Journal of Animal Science and Technology
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• v.50 no.2
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• pp.199-208
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• 2008

This study was undertaken to investigate the effects of ruminally protected amino acids (Methionine and Lysine) on in vitro ruminal parameters, and in vivo milk yield and milk composition in mid-lactating cows. In the first in vitro experiment, there were no statistical significances between treatments in ruminal pH and dry matter digestibility during various incubation times. In the second in vivo experiment, milk yield decreased by 11.92% in control and 5.68% in the treatment respectively, but decrease rate of milk yield in the treatment was lower than control. Milk yields naturally decreased as time goes by since the DIMs(Days in milk) of the cows in experiment were in mid-lactation period. 4% FCM(Fat corrected milk) and milk protein yields also, respectively, decreased by 11.25% and 11.09% in control and 6.16% and 5.47% in the treatment as compared with the intial. Milk protein and milk fat production were higher in the treatment(0.90kg, 1.10kg) than those of control(0.66kg, 0.79kg). Milk fat content significantly increased with supplementing protected amino acids as compared to control(P<0.05). From the above results, protected amino acids were positively utilized in the performances of mid-lactating cows without inhibiting rumen fermentation. Further investigation is suggested for essential amino acid composition and intestinal digestion rate out of rumen bypass protein in dietary protein to be estimated.

• Journal of Dairy Science and Biotechnology
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• v.41 no.1
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• pp.34-43
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• 2023

Hydrolysis of whey-derived proteins using lactic acid bacteria (LAB) utilizes the mass culture method and fermentation of LAB to produce effective bioactive peptides. Whey protein has the biological potential of its precursors, but the active fragments may not be released depending on the hydrolysis method. As an alternative to these problems, the nutritional and bioactive functionality of the hydrolysis method have been reported to be improved using LAB for whey protein. Peptide fractions were obtained using a sample fast protein liquid chromatography device. Antioxidant activity was verified for each of the five fractions obtained. In vitro cell experiments showed no cytotoxicity and inhibited nitric oxide production. Cytokine (IL [interleukin]-1α, IL-6, tumor necrosis factor-α) production was significantly lower than that of lipopolysaccharides (+). As a result of checking the amino acid content ratio of the fractions selected through the AccQ-Tag system, 17 types of amino acids were identified, and the content of isoleucine, an essential amino acid, was the highest. These properties show their applicability for the production of functional products utilizing dietary supplements and milk. It can be presented as an efficient method in terms of product functionality in the production of uniform-quality whey-derived peptides.

• Journal of Dairy Science and Biotechnology
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• v.27 no.1
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• pp.19-28
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• 2009

Lactoferrin was first identified 60 years ago as a "red protein" in bovine milk. Lactoferrin, one of the transferrin family proteins, is an iron-binding glycoprotein found in milk and various mucosal secretions; it is also released from activated neutrophils. Human lactoferrin has a molecular weight of 82.4 kDa and is composed of 702 or 692 amino acid residues. Bovine lactoferrin has a molecular weight of 83.1 kDa and is composed of 689 amino acid residues. Both lactoferrin and transferrin have the ability to bind two $Fe^{3+}$ ions, together with two ${CO_3}^{2-}$ ions with extremely high affinity; these proteins also have the ability to release this iron at low pH levels. The polypeptide chain in lactoferrin is folded into two globular lobes, representing the N-terminal and C-terminal halves. Both lobes have similar folding and 40% sequence identity. This protein is capable of multiple functions as described in various review papers, including antimicrobial, antiviral, antiinflammatory, anticancer, antioxidant, and cell growth-promoting activities. Lactoferrin also exhibits immunomodulating effects and plays an active role in the regulation of myelopoiesis and the inhibition of bacterial translocation.

• Journal of Practical Agriculture & Fisheries Research
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• v.8 no.1
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• pp.43-51
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• 2006

An experiment was conducted to examine how the response of dairy cows to a change from twice to thrice-daily milking is affected by deficiencies in the dietary supplies of three amino acids, His, Met and Lys. The amino acid deficiencies were obtained by feeding the cows a diet of grass silage and a cereal-based supplement containing feather meal as the sole protein supplement. Taken overall, the results show that when cows were given the feather meal diet, even though dietary ME was in considerable excess, a deficiency of specific amino acids prevented any increase in milk yield in response to increasing the frequency of milking from twice to thrice daily. The results of half-udder milking showed that when cows consumed the diet deficient in amino acids, milking one half of the gland more frequently reduced the secretion of protein and lactose by the control gland. Neither MBF nor the ratio of 3-MH/creatinine in urine was affected by thrice-daily milking. The present results go a stage further in showing that, against a background of insufficient dietary amino acids, the stimulus of thrice-daily milking is not sufficient to induce a measurable change in the partition of amino acid use between body and udder.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.2
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• pp.241-249
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• 2016

The supplementation of livestock feed with animal protein is a present cause for public concern, and plant protein shortages have become increasingly prominent in China. This conflict may be resolved by fully utilizing currently available sources of plant protein. We estimated the rumen degradability and the small intestinal digestibility of the amino acids (AA) in rapeseed meal (RSM), soybean meal (SBM), sunflower seed meal (SFM) and sesame meal (SSM) using the mobile nylon bag method to determine the absorbable AA content of these protein supplements as a guide towards dietary formulations for the dairy industry. Overall, this study aimed to utilize protein supplements effectively to guide dietary formulations to increase milk yield and save plant protein resources. To this end, we studied four cows with a permanent rumen fistula and duodenal T-shape fistula in a $4{\times}4$ Latin square experimental design. The results showed that the total small intestine absorbable amino acids and small intestine absorbable essential amino acids were higher in the SBM (26.34% and 13.11% dry matter [DM], respectively) than in the SFM (13.97% and 6.89% DM, respectively). The small intestine absorbable Lys contents of the SFM, SSM, RSM and SBM were 0.86%, 0.88%, 1.43%, and 2.12% (DM basis), respectively, and the absorbable Met contents of these meals were 0.28%, 1.03%, 0.52%, and 0.47% (DM basis), respectively. Among the examined food sources, the milk protein score of the SBM (0.181) was highest followed by those of the RSM (0.136), SSM (0.108) and SFM (0.106). The absorbable amino acid contents of the protein supplements accurately reflected protein availability, which is an important indicator of the balance of feed formulation. Therefore, a database detailing the absorbable AA should be established.

• Food Science of Animal Resources
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• v.29 no.5
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• pp.566-572
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• 2009

This study was designed to elucidate the quantities of milk nutrients entrapped during cholesterol removal from milk by crosslinked $\beta$-cyclodextrin ($\beta$-CD, 0.4~1.2%, w/v) and to evaluate the amounts of the residual $\beta$-CD in cholesterol-reduced milk treated by crosslinked $\beta$-CD. The content of lactose in the control milk (without treatment by crosslinked $\beta$-CD) was 4.86%, and the amounts of lactose entrapped by crosslinked $\beta$-CD ranged from 0.00 to 0.03%. The total amounts of the entrapped short-chain free fatty acid (FFA) and free amino acid (FAA) ranged from 0.03 to 0.09 ppm and from 0.28 to $0.71{\mu}mol/mL$, respectively. The amounts of the entrapped water-soluble vitamins (L-ascorbic acid, niacin, thiamine and riboflavin) ranged from 0.02 to 0.05 ppm, 0.01 to 0.06 ppm, 0.00 to 0.06 ppm and 0.01 to 0.06 ppm, respectively. The entrapped amounts of lactose, short-chain FFAs, FAAs and water-soluble vitamins were not remarkably affected by the concentrations of crosslinked $\beta$-CD (0.4~1.2%, w/v). Only very small amounts of residual $\beta$-CD in the cholesterol-removed milk were measured (1.22~3.00 ppm). Based on the data obtained from the present study, it was concluded that the amounts of entrapped nutrients were negligible during cholesterol removal from milk by crosslinked $\beta$-CD, and only trace amounts of residual $\beta$-CD were present in cholesterol-removed milk.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.5
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• pp.659-666
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• 2009

Metabolizable protein (MP) supply and amino acid balance in the intestine were manipulated through selection of highly digestible rumen-undegradable protein (RUP) sources and protected methionine (Met) supplementation. Four ruminallycannulated, multiparous Holstein cows averaging 193${\pm}$13 days in milk were used in a 4${\times}$4 Latin square design to assess N utilization and milk production responses to changes in RUP level, post-ruminal RUP digestibility and protected Met supplementation. Treatments were A) 14.0% crude protein (CP), 8.0% rumen degradable protein (RDP) and 6.0% RUP of low intestinal digestibility (HiRUP-LoDRUP); B) 14.1% CP, 8.1% RDP and 6.0% RUP of high intestinal digestibility (HiRUP-HiDRUP); C) 13.1% CP, 7.9% RDP and 5.2% RUP of high intestinal digestibility (LoRUP-HiDRUP), and D) 13.1% CP, 7.9% RDP and 5.2% RUP of high intestinal digestibility plus rumen escape sources of Met (LoRUP-HiDRUP+Met). Experimental diets were formulated to have similar concentrations of RDP, net energy of lactation ($NE_L$), neutral detergent fiber (NDF), acid detergent fiber (ADF), calcium, phosphorus and ether extract using the NRC model (2001). Results showed that dry matter intake (DMI), production of milk fat and protein were similar among treatments. Milk production was similar for diet HiRUP-LoDRUP, HiRUP-HiDRUP and LoRUP-HiDRUP+Met, and significantly higher than diet LoRUP-HiDRUP. Milk fat and protein percentage were higher for cows receiving HiDRUP treatments, with the greatest increases in the diet LoRUP-HiDRUP+Met. There was no significant change in ruminal pH, $NH_3g-N$ and volatile fatty acid (VFA) concentration among all treatments. Apparent digestibility of dry matter (DM), CP, NDF and ADF and estimated bacterial CP synthesis were similar for all treatments. Nitrogen intakes, blood and milk urea-N concentrations were significantly higher for cows receiving HiRUP diets. Urine volume and total urinary N excretion were significantly lowered by LoRUP diets. Lowering dietary RUP level while supplementing the highly digestible RUP source with rumen escape sources of Met resulted in similar milk production, maximal milk fat and protein concentration and maximum N efficiency, indicating that post-ruminal digestibility of RUP and amino acid balance in the small intestine can be more important than total RUP supplementation.

• The Korean Journal of Community Living Science
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• v.14 no.2
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• pp.63-70
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• 2003

In this experiment, the curd was made from soybean and cow's milk in the ratio of 7 to 3, and coagulated with Glucono-delta-lacton(GDL) and $CaSO_4&.$2H_{2}O& in the 1:1 ratio. During the procedure, the mulberry leaf powder was added. The amount of the added powder varied from 0.1 % to 0.5 %. This experiment aimed to show the change of yield, general components, minerals, amino acid, changes of pH, sensory properties of these products. As mulberry leaf powder addition increased, crude protein, crude fat, crude ash content, minerals and amino acids increased. Whereas moisture content decreased, and in particular,$Ca^{++}$, $K^+$ and $Na^+$ increased. On the other hand, in the sensory properties, the levels of satisfaction about the color, appearance, flavor, texture and savory were lower in mulberry leaf powder added than under control.