• Applied Biological Chemistry
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• 제36권6호
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• pp.416-423
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• 1993

건조방법 및 원료성분을 달리하여 분유를 제조하고 이들분유의 몇 가지 리올로지 특성을 Instron Universal Testing Machine으로 측정하여 얻어진 결과는 다음과 같다. 드럼건조된 전지분유의 부피밀도는 $0.382\;g/cm^3$으로 탈지 및 조제 분유보다 높았고, 분무 건조된 탈지 분유의 Hausner ratio, 평정각 및 compressibility 는 각각 1.127, $32.5^{\circ}$, 0.029로 탈지 분유는 자유롭게 흐르는 것을 보여주었으며, 드럼건조된 전지분유의 compressibility는 수분 함량이 4.96%에서 3.89%로 감소함에 따라 0.079에서 0.052로 낮아졌다. 전지분유 그래뉼의 compressibility는 0.056으로서 분유의 compressibility보다 낮았다. 분무 건조된 분유는 구형으로서, 동결건조나 드럼건조된 분유보다 더 견고함을 나타냈다.

• 한국축산식품학회지
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• 제35권3호
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• pp.360-369
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• 2015

Milk proteins have many potential sequences within their primary structure, each with a specific biological activity. In this study, we compared and investigated the bioactivities of hydrolysates of the domestic (A, B) and imported (C, D) skim milk powders generated using papain digestion. MALDI-TOF analysis revealed that all milk powder proteins were intact, indicating no autolysis. Electrophoretic analysis of hydrolysates showed papain treatment caused degradation of milk proteins into peptides of various size. The antioxidant activity of the hydrolysates, determined using 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and total phenolic contents (TPC) assays, increased with incubation times. In all skim milk powders, the antioxidant activities of hydrolysates were highest following 24 h papain treatment (TPC: A, 196.48 μM GE/L; B, 194.52 μM GE/L; C, 194.76 μM GE/L; D, 163.75 μM GE/L; ABTS: A, 75%; B, 72%; C, 72%; D, 57%). The number of peptide derived from skim milk powders, as determined by LC-MS/MS, was 308 for A, 283 for B, 208 for C, and 135 for D. Hydrolysate A had the highest antioxidant activity and the most potential antioxidant peptides amongst the four skim milk powder hydrolysates. A total of 4 β-lactoglobulin, 4 α_s1-casein, and 56 β-casein peptide fragments were identified as potential antioxidant peptides in hydrolysate A by LC-MS/MS. These results suggest that domestic skim milk could have applications in various industries, i.e., in the development of functional foods.

• 한국축산식품학회지
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• 제42권6호
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• pp.915-927
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• 2022

Recently, protein-fortified milk powders are being widely consumed in Korea to prevent sarcopenia, and the demand for high-protein food powders is continuously increasing in the Korean market. However, spray-dried milk proteins have poor flowability and wettability owing to their fine particle sizes and high inter-particle cohesive forces. Fluidized bed agglomeration is widely used to improve the instant properties of food powders. This study investigated the effect of fluidized bed agglomeration on whey protein isolate (WPI)-fortified skim milk powder (SMP) at different SMP/WPI ratios. The fluidized bed process increased the particle size distribution, and agglomerated particles with grape-like structures were observed in the SEM images. As the size increased, the Carr index (CI) and Hausner ratio (HR) values of the agglomerated WPI-fortified SMP particles exhibited excellent flowability (CI: <15) and low cohesiveness (HR: <1.2). In addition, agglomerated WPI-fortified SMP particles exhibited the faster wetting time than the instant criterion (<20 s). As a result, the rheological and physical properties of the WPI-fortified SMP particles were effectively improved by fluidized bed agglomeration. However, the fluidized bed agglomeration process led to a slight change in the color properties. The CIE L^* decreased, and the CIE b^* increased because of the Maillard reaction. The apparent viscosity (η_a,10) and consistency index (K) values of the rehydrated solutions (60 g/180 mL water) increased with the increasing WPI ratio. These results may be useful for formulating protein-fortified milk powder with better instant properties.

• Journal of Dairy Science and Biotechnology
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• 제40권3호
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• pp.134-142
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• 2022

Protein-enriched dairy powder is widely consumed to promote muscle synthesis. Recently, in Korea, elderly people have also begun consuming protein powder products to prevent muscle loss. However, these protein-enriched powders have poor flowability and hydration properties because of the fine particles of spray-dried milk protein powder. Therefore, in this study, the fluidized bed agglomeration process was used to solve these problems. The rheological and physical properties of milk protein isolate (MPI)/skim milk powder (SMP) mixtures were effectively improved via fluidized bed agglomeration. The particle size of the MPI/SMP mixtures significantly increased from 35.7-58 ㎛ to 118-136 ㎛, the flowability level improved from fair (21.4-26.3) to good (15.7-16.3), and the cohesiveness level changed from intermediate (1.27-1.36) to low (1.18-1.19) after fluidized bed agglomeration. In addition, the wetting time of the agglomerated MPI/SMP mixtures was effectively reduced to 4.67-58.3 s by fluidized bed agglomeration. These findings may be useful for manufacturing protein-enriched dairy powders with good instant properties.

• Journal of Animal Science and Technology
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• 제46권4호
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• pp.667-676
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• 2004

본 연구는 상업용 혼합균주인 L. delbrueckii ssp. bulgricus와 S. salivarius ssp. thermophillus를 사용하여 쌀 분말과 탈지분유의 첨가량을 달리하여 요르트를 제조한 후 배양 시간의 경과에 따른 pH와 산도, 젖산균 수, 점도, 유기산, 탄수화물의 종류와 함량 및 관능성을 측정하여 최적의 기질로 사용할 수 있는 쌀 분말과 탈지분유의 적정 첨가량을 선정하였다. 대조구는 배양 10시간째 요구르트의 적정 pH인 4.5에 도달하였으나 쌀 분말을 4%, 6% 첨가한 시료는 배양 6시간째, 탈지분유를 첨가한 시료는 첨가량에 관계없이 배양 8시간째 적정 산도에 도달 하였다. 산도는 대조구의 경우 배양 4시간째 적정 산도인 1.0에 도달하였으나 쌀 분말과 탈지분유를 첨가한 시료는 첨가량에 관계없이 배양 4시간째 적정 산도를 초과하였다. 쌀 분말을 4% 첨가한 시료와 탈지분유를 4%, 6% 첨가한 시료는 배양 4시간째에 젖산균의 수가 가장 많이 증가하였다. 점도는 쌀 분말의 경우 4% 이상 첨가하면 casein이 커드 형성에 영향을 받는 것으로 나타났다. 탈지분유를 6% 첨가한 시료를 제외하고는 모두 대조구보다 lactic acid의 함량이 증가하였으며 쌀 분말을 4% 참가한 시료에서 galactose가 가장 많이 생성되었다. 관능검사는 각 항목별로 시료 간에 통계적인 유의차는 없었으나 색과 맛, 전체적인 기호도에 있어서 탈지분유를 4% 첨가한 시료가 가장 높은 값을 나타내었으며 풍미와 조직감에 있어서는 쌀 분말을 4% 첨가한 시료가 가장 높은 값을 나타내었다. 따라서 본 실험에서는 쌀 분말과 탈지분유의 최적 첨가량은 각각 4%로 나타났다.

• 한국축산식품학회지
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• 제31권6호
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• pp.827-833
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• 2011

The objective of this study was to develop a fluorogenic real-time PCR-based assay for detecting and quantifying amounts of cow milk in cow/goat milk mixtures or goat milk products. In order to quantify the exact amount of cow milk in cow/goat raw milk mixtures and commercial goat milk products, it was necessary to achieve quantitative extraction of total genomic DNA from the raw milk matrix. Both mammalian-specific PCR and cow-specific PCR were performed. A cow-specific 252 bp band obtained from the raw cow milk and raw goat milk mixtures, commercial goat milk, and two goat milk powders was identified, along with the relationship between the cow milk amount and band intensity of the electrophoresis image. The detection threshold was found to be 0.1%. The expression of cow's 12S rRNA in the cow/goat milk mixtures, commercial goat milk, and two goat milk powders was identified. The expression quantity of the milk 12S rRNA increased with increasing ratios of the cow/goat milk mixtures. Using these calibrated relative expression levels as a standard curve in the cow/goat raw milk mixtures, the contents of cow milk were 1.8% in the commercial goat milk, 9.6% in goat milk powder A, and 11.6% in goat milk powder C. However, cow milk was not detected in goat milk powder B.

• 한국축산식품학회지
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• 제35권4호
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• pp.572-576
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• 2015

The most commonly used infant formulas contain lactose originating from cow milk. Goat milk has recently been claimed to be nutritionally more effective for infants than other milks. In baby foods, much emphasis is placed on the concentrations of intestinal microflora-promoting oligosaccharides, which are generally transferred into lactose from milk during crystallization process. Here we show that higher level of free sialic acid is present in goat lactose powder compared to cow lactose powder. Without proteinase K treatment, the amount of 3-sialyllactose and 6-sialyllactose were similar in goat and cow lactose powders. However, after proteolysis, 6-sialyllactose was present at higher levels in goat than in cow lactose powder. Galactooligosaccharides, a group of prebiotics, are present in milk in the form of glycoproteins. Galactooligosaccharide content was also higher in goat lactose powder than in cow lactose powder.

• 한국축산식품학회지
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• 제18권4호
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• pp.285-291
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• 1998

Adsorption isotherms of water vapour for infant formula milk powders manufactured by P. M. and N company in Korea were measured at temperatures between 20, 30 and 40$^{\circ}C$ using COST-90 modified method. Results showed that the isotherms were sigmoidal in shape. The adsorption isotherms of milk powder were depending on the temperature and products. The BET-model were applied and analyzed to compare the experimental value. It was found that the BET-model is fitted with measuring data. Sample P showed the lowest monolayer value and sample N showed the highest. Isosteric heat obtained upon application of BET-model was calculated in this field of temperature using the Clausius-Clapeyron equation. It is suggested that the usage of the BET-model to estimate the heat of water sorption in infant formula milk powder should be in agreement with the results from COST-90 project.

• Asian-Australasian Journal of Animal Sciences
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• 제19권10호
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• pp.1503-1507
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• 2006

Goats' milk adulteration with cows' milk is becoming a big problem. In the past, the urea-polyacrylamide gel electrophoresis assay with different motility of ${\alpha}S1$-casein has been applied for the identification of cows' milk adulteration. The detection sensitivity is 1.0%. The aim of this study was to develop a faster and more sensitive method to detect cows' milk which may be present in adulterated goats' milk and goats' milk powder. The published primer was targeted at highly conserved regions in bovine mitochondrial DNA (a 271 bp amplicon). This amplicon was cloned and sequenced to further confirm bovine specific sequence. The chelex-100 was used to separate bovine somatic cells from goats' milk or goats' milk powder samples. Random sampling of different brands of goats' milk powder and tablets from various regions of Taiwan showed the adulterated rate was 20 out of 80 (25%) in goats' milk powders and 12 out of 24 (50%) in goats' milk tablets. With this system, as low as 0.1% cows' milk or cows' milk powder in goat milk or goat milk powder could be identified. This chelex DNA isolation approach provides a fast, highly reproducible and sensitive method for detecting the adulteration of goats' milk products.

• 농업과학연구
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• 제38권3호
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• pp.485-491
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• 2011

Yogurt was prepared from skim milk added with 2, 4 or 6% of green whole grain of barley, wheat, glutinous rice and common rice, respectively. Changes in pH, titratable acidity, viable cell counts and viscosity during fermentation were monitored and its sensory evaluation was also performed. The optimum level of additives such as green whole grain of barley, wheat, glutinous rice and common rice for yogurt manufacture was selected to 2%. The samples added with green whole grain of barley and wheat powders reached pH 4.5 in 12 hours. After 4 hours of fermentation, pH, the viable cell counts and viscosity in samples added with 2% green whole grain of barley, wheat, glutinous rice and common rice powders were the highest. Especially, in overall sensory evaluation using 5 parameters, the sensory scores of glutinous rice and common rice 2% yogurts were significantly high. From this experiment, the additives optimum level of glutinous rice and common rice powders was selected to be 2%.