• 한국축산식품학회지
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• 제23권4호
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• pp.356-360
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• 2003

우유의 셀렌 함량을 측정하기 위하여 ICP-OES를 이용한 분석법을 확립하였다. 시료전처리는 우유의 수분을 제거한 후 질산과 과산화수소를 이용하여 유기성분을 제거하였고, 최종적으로 다시 과산화수소로 미량의 유기성분을 산화시켰다. 셀렌은 휘발성 무기성분이므로 전처리된 용액에 NaBH$_4$와 HCl을 이용하여 셀렌의 수소화(hydride)반응으로 끓는점을 높이고 분석감도를 향상시켰다. 수소화 반응 중 HCl 농도의 최적조건은 2 mol/L에서 최대 cps(counter per sec)로 나타났고, NaBH$_4$와 시료 유속의 최적조건은 각각 1.5%와 1.2mL/min인 것으로 나타났다. 따라서 위의 HG 조건이 시료 메트릭스에 따른 간섭효과를 제거하였으며, 최적의 정량조건임을 알 수 있었다. 이 조건으로 표준물질을 이용한 셀렌의 직선성 상관계수(R)는 0.98로서 우유에 함유된 셀렌 분석에 적용할 수 있었다. Standard addition method를 이용한 회수율은 10 ppb에서 88.0% 이었고, 첨가된 농도가 증가할수록 회수율 및 RSD는 정확성 및 정밀성을 확보할 수 있었다.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제25권3호
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• pp.194-210
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• 2022

Human milk contains a number of nutritional and bioactive molecules including microorganisms that constitute the so-called "Human Milk Microbiota (HMM)". Recent studies have shown that not only bacterial but also viral, fungal, and archaeal components are present in the HMM. Previous research has established, a "core" microbiome, consisting of Firmicutes (i.e., Streptococcus, Staphylococcus), Proteobacteria (i.e., Serratia, Pseudomonas, Ralstonia, Sphingomonas, Bradyrhizobium), and Actinobacteria (i.e., Propionibacterium, Corynebacterium). This review aims to summarize the main characteristics of HMM and the role it plays in shaping a child's health. We reviewed the most recent literature on the topic (2019-2021), using the PubMed database. The main sources of HMM origin were identified as the retrograde flow and the entero-mammary pathway. Several factors can influence its composition, such as maternal body mass index and diet, use of antibiotics, time and type of delivery, and mode of breastfeeding. The COVID-19 pandemic, by altering the mother-infant dyad and modifying many of our previous habits, has emerged as a new risk factor for the modification of HMM. HMM is an important contributor to gastrointestinal colonization in children and therefore, it is fundamental to avoid any form of perturbation in the HMM that can alter the microbial equilibrium, especially in the first 100 days of life. Microbial dysbiosis can be a trigger point for the development of necrotizing enterocolitis, especially in preterm infants, and for onset of chronic diseases, such as asthma and obesity, later in life.

• Bulletin of the Korean Chemical Society
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• 제32권4호
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• pp.1315-1320
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• 2011

Whey protein (WP) is a mixture of proteins, and is of high nutritional values. WP has become an important source of functional ingredients in various health-promoting foods. In this study, size-exclusion chromatography (SEC) and asymmetrical flow field-flow fractionation (AsFlFFF) were used for separation and analysis of whey proteins. It was found that a lab-prepared WP from raw milk is mostly of ${\beta}$-lactoglobulin with small amount of higher molecular weight components, while a commercial whey protein isolate (WPI) powder contains relatively larger amount of components other than ${\beta}$-lactoglobulin, including IgG and protein aggregates. Results suggest that AsFlFFF provides higher resolution for the major whey proteins than SEC in their normal operation conditions. AsFlFFF could differentiate the BSA and Albumin, despite a small difference in their molecular weights, and also was able to separate much smaller amount of aggregates from monomers. It is noted that SEC was able to show the presence of low molecular weight components other than the major whey proteins in the WP samples, which AsFlFFF could not show, probably due to the partial loss of those low molecular weight species through the membrane.

• Preventive Nutrition and Food Science
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• 제10권3호
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• pp.224-230
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• 2005

The effects of low viscosity chitosan on the rheological properties of soymilk using a model system and on tofu qualities were examined. The flow behavior of soy milk with chitosan closed the Newtonian flow and stabilized according to increasing chitosan concentration. The soymilk containing $glucono-\delta-lactone$ exhibited a more pseudoplastic flow behavior compared with that of the control soymilk. The addition of low viscosity chitosan to the tofu preparation did not significantly affect its physicochemical properties. However, the results of the TEM image and instrumental textural properties showed that low viscosity chitosan affected the construction of the tofu structure. Chitosan tofu had low scores across the whole field of appearance in the sensory evaluation, and its overall eating quality was scored significantly lower. These results suggest that the addition of low viscosity chit os an affects the quality of tofu, which changes according to the degree of polymerization and concentration of chitosan.

• 한국식품과학회지
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• 제31권2호
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• pp.509-515
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• 1999

본 연구에서는 난백분말과 카제인을 기질로 한 시료에 생육촉진물질(growth stimulating agent: GSA)을 첨가하여 젖산균의 생육과 산생성 및 젖산균 발효식품의 관능성과 점도에 미치는 영향을 관찰하였다. GSA 첨가로 젖산균의 산생성이 촉진되었으며, 0.3%보다 1%에서 그 효과가 더 높았다. 시료에 따라서는 GSA 첨가시료의 산도가 우유시료와 차이가 없는 것도 있었다. 그러나 GSA의 첨가로 인한 생균수의 증가는 뚜렷하지 않았다. 세 균주 중에서 L. acidophilus로 발효시킨 시료의 산도가 다른 균주보다 대체적으로 높았다. GSA 첨가농도는 1%가 가장 적합하였다. 발효시간을 달리하여 실시한 시료의 관능검사 결과 18 hr시료의 관능성이 가장 우수하였다. 한편 우유시료에 비하여 GSA 첨가시료는 유청의 분리가 상대적으로 많고, GSA 특유의 맛과 냄새가 있어 전반적인 기호도와 맛이 다소 저조하였다. 우유시료와 control 시료의 점도가 GSA 첨가시료보다 유의적으로 높았고 (p<0.05), GSA를 첨가한 4시료 사이에는 유의적인 차이가 없었다. 모든 시료는 시간이 경과함에 따라 점도가 서서히 감소하는 현상, 즉 thixotopic flow의 특성을 나타냈다.

• Restorative Dentistry and Endodontics
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• 제20권1호
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• pp.342-350
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• 1995

To determine the factors which affect the flow of dentinal fluid through cat dentinal tubules in vivo, the flow of fluid was measured by observing the movement of the fat droplets of dilute milk in a glass capillary with a microscope connected to the monitor. After measuring the exposed area of dentin, hydraulic conductances of dentin were calculated. The mean pressure which stoped the outward flow of dentinal fluid was 9.5mmHg. The hydraulic conductance of dentin under the condition of pulp exposed was increased by 21 % from that under the condition of dentin exposed. Under the conditions of pulp cut and pulp removed, the hydraulic conductances of dentin were increased by 22 % and 31 % respectively from that under the condition of dentin exposed. These results show that the direction and rate of dentinal fluid flow in cat dentin is affected mainly by the hydrostatic pressure of interstitial fluid of pulp tissue in the state of low compliance. Both of the osmotic effect produced by the protein constituents of interstitial fluid across the odontoblast tell layer and the change of interstitial fluid pressure produced by the state of the microcirculation of the pulp also affect the direction and rate of dentinal fluid in some degree.

• Asian-Australasian Journal of Animal Sciences
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• 제30권5호
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• pp.653-659
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• 2017

Objective: This trial was performed to examine the effects of ruminally degradable starch (RDS) levels in total mixed ration (TMR) with low corn-based starch on the milk production, whole-tract nutrient digestibility and nitrogen balance in dairy cows. Methods: Eight multiparous Holstein cows (body weight [BW]: $717{\pm}63kg$; days in milk [DIM]: $169{\pm}29$) were assigned to a crossover design with two dietary treatments: a diet containing 62.3% ruminally degradable starch (% of total starch, low RDS) or 72.1% ruminally degradable starch (% of total starch, high RDS). Changes to the ruminally degradable levels were conducted by using either finely ground corn or steam-flaked corn as the starch component. Results: The results showed that dry matter intake, milk yield and composition in dairy cows were not affected by dietary treatments. The concentration of milk urea nitrogen was lower for cows fed high RDS TMR than low RDS TMR. The whole-tract apparent digestibility of neutral detergent fiber, acid detergent fiber and crude protein decreased, and that of starch increased for cows fed high RDS TMR over those fed low RDS TMR, with no dietary effect on the whole-tract apparent digestibility of dry matter and organic matter. The proportion of urinary N excretion in N intake was lower and that of fecal N excretion in N intake was higher for cows fed high RDS TMR than those fed low RDS TMR. The N secretion in milk and the retention of N were not influenced by the dietary treatments. Total purine derivative was similar in cows fed high RDS TMR and low RDS TMR. Consequently, estimated microbial N flow to the duodenum was similar in cows fed high RDS TMR and low RDS TMR. Conclusion: Results of this study show that ruminally degradable starch levels can influence whole-tract nutrient digestibility and nitrogen balance in dairy cows fed low corn-based starch diets, with no influence on performance.

• Animal Bioscience
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• 제37권3호
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• pp.509-521
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• 2024

Objective: It was shown that microRNAs (miRNAs) play an important role in milk protein synthesis. However, the post-transcriptional regulation of casein expression by exogenous miRNA (xeno-miRNAs) in ruminants remains unclear. This study explores the regulatory roles of alfalfa xeno-miR162 on casein synthesis in bovine mammary epithelial cells (bMECs). Methods: The effects of alfalfa xenomiR-162 and G protein subunit gamma 11 (GNG11) on proliferation and milk protein metabolism of bMECs were detected by 5-Ethynyl-2'-Deoxyuridine (EdU) staining, flow cytometry, cell counting kit-8 (CCK-8), enzyme-linked immunosorbent assay, quantitative real-time polymerase chain reaction (qRT-PCR), and Western blot. Dual-luciferase reporter assay was used to verify the targeting relationship between GNG11 and xenomiR-162. Results: Results showed that over-expression of xenomiR-162 inhibited cell proliferation but promoted apoptosis, which also up-regulated the expression of several casein coding genes, including CSN1S1, CSN1S2, and CSN3, while decreasing the expression of CSN2. Furthermore, the targeting relationship between GNG11 and xenomiR-162 was determined, and it was confirmed that GNG11 silencing also inhibited cell proliferation but promoted apoptosis and reduced the expression of casein coding genes and genes related to the mammalian target of rapamycin (mTOR) pathway. Conclusion: Alfalfa xenomiR-162 appears to regulate bMECs proliferation and milk protein synthesis via GNG11 in the mTOR pathway, suggesting that this xeno-miRNA could be harnessed to modulate CSN3 expression in dairy cows, and increase κ-casein contents in milk.

• Asian-Australasian Journal of Animal Sciences
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• 제16권10호
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• pp.1460-1468
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• 2003

An experiment was conducted to quantify the flow of soluble non-ammonia nitrogen (SNAN) in the liquid phase of ruminal (RD) and omasal digesta (OD), and to investigate diurnal pattern in SNAN flow in OD. Five ruminally cannulated Finnish-Ayrshire dairy cows in a $5{\times}5$ Latin square design consumed a basal diet of grass silage and barley grain, and that supplemented with four protein feeds (kg/d DM basis) as follows: skimmed milk powder (2.1), wet distiller' solubles (3.0), untreated rapeseed meal (2.1) and treated rapeseed meal (2.1). Ruminal digesta was sampled using a vacuum pump, whereas OD was collected using an omasal sampling system at 1.0 h interval during a 12 h feeding cycle. Both RD and OD were acidified, centrifuged to remove microbes and precipitated with trichloroacetic acid followed by centrifugation. The SNAN fractions (free amino acid (AA), peptide and soluble protein) in RD and OD were assessed using ninhydrin assay. Free AA, peptide and soluble protein averaged 60.0, 89.4 and 2.1 g/d, respectively, for RD, and 81.8, 121.5 and 2.5 g/d, respectively, for OD. Although free AA flow was relatively high, mean peptide flow was quantitatively the most important fraction of SNAN, indicating that degradation of peptide to AA rather than hydrolysis of soluble protein to peptide or deamination may be the most limiting step in rumen proteolysis. Diurnal pattern in flow of peptide including free AA in OD during a 12 h feeding cycle peaked 1 h post-feeding, decreased by 3 h post-feeding and was relatively constant thereafter. Protein supplementation showed higher flow of peptide including free AA immediately after feeding compared with no supplemented diet. There were no differences among protein supplements in diurnal pattern in flow of peptide including free AA in OD.

• 한국식품과학회지
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• 제25권6호
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• pp.747-752
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• 1993

본 연구에서는 우유에 탈지분유 또는 4종의 전분(쌀전분, 밀전분, 옥수수전분, 감자전분)을 각각 첨가하고 젖산균(Lactobacillus 4종)으로 발효하여 호상의 요구르트를 만든 후, 전분의 첨가가 젖산균의 산생성 및 요구르트의 품질(점도, 관능성, 휘발성 향기 성분)에 미치는 영향을 조사하였다. 전분의 첨가로 젖산균의 산생성이 대조군(우유로만 만든 요구르트)보다 현저하게 촉진되었으며, 접종된 4종의 젖산균 중에서는 L. jugurti의 산생성이 가장 우수하였다. 전분이 첨가된 호상요구르트의 점도는 대조군보다 대체적으로 유의성있게 높았다(p<0.05). 호상요구르트는 전단속도를 증가시킴에 따라 점도가 감소하였으며 thixotropic flow의 특성을 나타냈다. 관능검사의 결과를 보면 옥수수전분 첨가시료와 쌀전분 첨가시료가 표준시료보다 다소 우수하였고 감자전분 첨가시료가 가장 저조하였다. GC에 의한 휘발성 향기 성분 분석에서는 호상요구르트에 함유된 휘발성분 가운데 acetaldehyde, acetone, ethanol 및 butanol의 4가지 성분이 확인되었다.