• 한국축산식품학회지
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• 제23권1호
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• pp.63-69
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• 2003

본 연구는 단백질분해효소로 whey protein을 가수분해하여 얻은 가수분해물의 용해도와 유화특성의 변화를 측정하기 위해 실시하였다. Whey protein concentrates를 porcine trypsin(E : S=1 ; 3,000)으로 pH 8.0, 37$^{\circ}C$에서 6시간 동안 가수분해한 whey protein 가수분해물의 유화활성은 분해 4시간째에 가장 높게 나타났으며, 이 때 가수분해도는 5.50%이었다. whey protein의 효소가수분해로 whey protein 중의 $\alpha$-lactalbumin은 분해가 잘 일어나지 않으나 $\beta$-lactoglobulin은 분해 초기부터 급속히 분해되며 유화력 상승에 관여하는 여 러개의 저분자량 peptide를 생성하였다. 가수분해물의 용해도는 가수분해시간이 지남에 따라 증가세를 보이다가 5시간부터 조금씩 감소 추세를 보였으며, pH에 따라서는 등전점 부근인 pH4~5에서 용해도가 가장 낮았으나 가수분해시간이 증가함에 따라 이 부근의 용해도가 현저히 증가하였으며 pH 6이상에서는 pH가 증가함에 따라 용해도도 증가하였다. 유화활성은 용해도의 결과와 거의 비슷한 결과를 나타내었다. 유화 안정성은 분해시간이 지남에 따라 조금씩 증가함을 보여주었으나, 가수분해 4시간부터 pH 8 이상의 PH에서 급격한 증자를 나타내었다.

• Asian-Australasian Journal of Animal Sciences
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• 제18권3호
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• pp.433-438
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• 2005

This investigation was undertaken in order to elicit the relationship between the extent of ultrafiltration processing of whey and its effect on composition and yield of resultant whey protein concentrate (WPC). Cheddar cheese whey was fractionated through ultrafiltration to an extent of 70, 80, 90, 95, 97.5% and 97.5% volume reduction followed by I stage and II stage diafiltration. After each level of ultrafiltration, the composition of WPC was monitored. Similarly, the initial whey was adjusted to 3.0, 6.2 and 7.0 pH levels and ultrafiltration was carried out to elicit the effect of pH of ultrafiltration on the composition. Further, initial whey was adjusted to different levels of whey protein content ranging from 0.5 to 1.0 per cent and subjected to ultrafiltration to different levels. The various range of retentate obtained were further condensed and spray dried in order to assess the yield of WPC per unit volume of whey used and the quantity of whey required to produce unit weight of product. With the progress of ultrafiltration, there was a progressive increase in protein content and decrease in lactose and ash content. The regression study led to good relationships with $R^2$ values of more than 0.95 between the extents of permeate removed and the resultant changes in composition of each of the constituents. Whey processed at pH 3.0 had significantly a very low ash content and high protein content as compared to processing at 6.2 and 7.0. The yield of WPC per unit volume of whey varied significantly with the initial protein content. Higher initial protein content led to higher yield of all ranges of WPC and the quantity of whey required per unit weight of spray dried WPC significantly reduced. Regression equations establishing the relationship between initial protein content of whey and the yield of various types of WPC have been derived with very high $R^2$ values of 0.99. This study revealed that, the yield and composition of whey can be monitored strictly by controlling the processing parameters and WPC can be produced depending on the food formulation requirement.

• 한국축산식품학회지
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• 제37권1호
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• pp.44-51
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• 2017

Heat treatment of milk aims to inhibit the growth of microbes, extend the shelf-life of products and improve the quality of the products. Heat treatment also leads to denaturation of whey protein and the formation of whey protein-casein polymer, which has negative effects on milk product. Hence the milk heat treatment conditions should be controlled in milk processing. In this study, the denaturation degree of whey protein and the combination degree of whey protein and casein when undergoing heat treatment were also determined by using the Native-PAGE and SDS-PAGE analysis. The results showed that the denaturation degree of whey protein and the combination degree of whey protein with casein extended with the increase of the heat-treated temperature and time. The effects of the heat-treated temperature and heat-treated time on the denaturation degree of whey protein and on the combination degree of whey protein and casein were well described using the quadratic regression equation. The analysis strategy used in this study reveals an intuitive and effective measure of the denaturation degree of whey protein, and the changes of milk protein under different heat treatment conditions efficiently and accurately in the dairy industry. It can be of great significance for dairy product proteins following processing treatments applied for dairy product manufacturing.

• 농업과학연구
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• 제50권2호
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• pp.281-294
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• 2023

As a byproduct obtained from cheese manufacture, whey protein was developed as a functional food that contains multi-functional proteins. In this study, the biochemical activity of fermented milk prepared by fortifying whey protein with excellent physiological activity was investigated. Immunoglobulin (IgG) content was higher in 10% fortified whey protein fermented milk than in the control. The viable cell counts were 20% higher in the fermented milk with 10% fortified whey protein than in the control group. The antibacterial effect of 10% fortified whey protein fermented milk compared to the control group was shown to be effective against four pathogenic microorganisms, Escherichia coli (KCTC1039), Pseudomonas aeruginosa 530, Salmonela Typhimurium (KCTC3216), and Staphylococcus aureus (KCTC1621). The antioxidant effect by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities wasincreased two-fold in 10% fortified whey protein fermented milk compared to the control. The 10% fortified whey protein fermented milk inhibited the expression of the inflammatory cytokines (interleukin [IL]-6, tumor necrosis factor [TNF]-α, and induced nitric oxide synthase [iNOS]) in a concentration-dependent manner. In a piglets feeding test, the weight gain with 10% fortified whey protein fermented milk was increased by 18% compared to the control group, and no diarrhea symptoms appeared. Our results clearly demonstrated that 10% fortified whey protein fermented milk could be a useful functional ingredient for improving health.

• Journal of Dairy Science and Biotechnology
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• 제25권1호
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• pp.1-7
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• 2007

유청을 기초로 하는 배지를 제조하여 Lactobacillus brevis를 배양하면서 유청 단백질로부터 기능성 펩타이드 생성을 알아보고자 하였다. Lb. brevis의 적정생장에 필요한 배지성분의 농도는 2% 유청 분말, 1%의 포도당 및 0.5%의 효모추출물이었다. Lb. brevis의 생장은 효모 추출물의 보충이 포도당의 보충보다 더 효과적이었다. 이 유청 배지에서 Lb. brevis의 생장은 2.0 ${\times}$ 10$^8$CFU/mL에 달하였다. 생장 후의 유청 배지를 10,000 ${\times}$ g에서 10분간 원심분리하여 그 여액으로부터 얻은 유청단백분해물은 ACE 효소 억제 효과가 나타났다. 분자량 8,000Da 이하로 부분 정제한 분획의 ACE에 대한 억제효과는 유청단백분해물의 64.7 ${\pm}$ 3.6%, IC$_{50}$은 38.8 ${\pm}$ 2.2 mg/mL로 나타났다. 따라서 유청을 기초로 한 배지는 젖산균으로부터 유청 단백질을 발효하여 ACE 억제 효과를 주는 펩타이드 생산에 적합한 배지임을 알 수 있었다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제2권2호
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• pp.122-125
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• 1997

The utilization of excess whey is necessary to reduce dairy waste because the large amount of whey disposal in waste streams has caused environmental problems. During whey protein film production as the effective means of utilization of excess whey, we have examined the effects of pH, temperature, and plasticizers for water vapor permeability(WVP), tensile strength(TS), and elongation rate(%E) of the whey protein films. The 10% whey protein films had the highest WVP(28.73g$.$mm/kPa$.$day$.$㎡) and TS(1.85${\pm}$0.11Mpa). But, in this case, an increase of WVP was caused by the thickness of whey protein films. At the concentration of 8% whey protein, appropriate thickness was obtained. Whey protein films prepared at the pH 6.75 and 95$^{\circ}C$ showed lower WVP(28.38g$.$mm/kPa$.$day$.$㎡) and elongation rate(12.9%) and higher TS value(3.769${\pm}$0.407 MPa) than at the pH 6.75 and 75$^{\circ}C$. As the temperature increased, WVP of films decreased slightly and tensile strength increased slightly, while elongation rate decreased significantly. Higher WVP and TS were observed at pH6.75 compared to pH7-9. In contrast, significantly higher elongation was observed at pH 9comapred to pH6.75-8. Among the plasticizer types used, the addition of sorbitol showed the highest TS value(6.244${\pm}$0.297 MPa) at the concentration 0.4g sorbitol and elongation rate(49%) at the concentration of 0.6g sorbitol.

• 한국축산식품학회지
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• 제32권5호
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• pp.627-634
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• 2012

This study was carried out to investigate the physical and thermal properties of ${\kappa}$-carrageenan (${\kappa}$-car) gel added whey protein isolate (WPI) as a cryoprotectant. The concentration of ${\kappa}$-carrageenan was fixed at 0.2 wt%. The mean ice crystal size of the WPI/${\kappa}$-car was decreased according to increasing whey protein isolate concentration. The temperature of gel-sol (Tg-s) and sol-gel (Ts-g) transition of WPI/${\kappa}$-car maxtrix was represented in the order of 3.0, 0.2, 5.0 and 1.0 wt%. In addition, the transition temperature of gel-sol of WPI in sucrose solution were showed in order of 1.0, 5.0, 0.2 and 3.0 wt% depending on whey protein isolate concentration. The shape of ice crystal was divided largely into two types, round and rectangular form. 1.0 wt% WPI/${\kappa}$-car matrix at pH 7 and 9 showed minute and rectangular formation of ice crystals and whey protein isolate in sucrose solution at a concentration of 1.0 wt% WPI/${\kappa}$-car matrix at pH 3 and 5 showed relatively large size and round ice crystals. The ice recrystallization characteristics and cryprotective effect of ${\kappa}$-carrageenan changed through the addition of different concentrations of whey protein isolate. It seems that the conformational changes induced interactions between whey protein isolate and ${\kappa}$-carrageenan affected ice recrystallization.

• Preventive Nutrition and Food Science
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• 제10권3호
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• pp.231-238
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• 2005

A standard $1\%$ w/v solution of CM-chitosan made from squid pen was added to milk at levels of $0.5\sim3\%$ (v/v) to improve the yield and rheological properties of cottage cheese by whey protein retention. Cheese curd did not form at levels higher than $3\%$ (v/v) CM-chitosan standard solution. Yield and total protein of cottage cheese increased up to $2\%\;by\;11\;to\;42\%\;and\;17\;to\;38\%$ respectively, compared to control cheese. Whey protein losses were decreased by 11 to $42\%$ and thus accounted for all of the increase in yield. Anomalous results were obtained at the $0.8\%$ level, which neither improved yield or whey protein retention nor stabilized rheological parameters, and at the $0.5\%$ level, which improved yield and total protein without increasing whey protein retention. Elasticity and cohesiveness of CM-chitosan-containing cheese were generally improved and stabilized during storage. Monitoring of cheese chromaticity values for four weeks revealed a delay in the onset of yellowing in cheeses with CM-chitosan compared to the controls, while the concentration of added CM-chitosan had little influence on cheese chromaticity. The addition of CM-chitosan solution could be applied directly to industrial scale cottage cheese-making without the need for any modification of the production process.

• 한국축산식품학회지
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• 제37권6호
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• pp.917-925
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• 2017

Whey protein, a by-product of milk curdling, exhibits diverse biological activities and is used as a dietary supplement. However, its effects on stress-induced vascular aging have not yet been elucidated. In this study, we found that whey protein significantly inhibited the Ang II-primed premature senescence of vascular smooth muscle cells (VSMCs). In addition, we observed a marked dose- and time-dependent increase in SIRT1 promoter activity and mRNA in VSMCs exposed to whey protein, accompanied by elevated SIRT1 protein expression. Ang II-mediated repression of SIRT1 level was dose-dependently reversed in VSMCs treated with whey protein, suggesting that SIRT1 is involved in preventing senescence in response to this treatment. Furthermore, resveratrol, a well-defined activator of SIRT1, potentiated the effects of whey protein on Ang II-primed premature senescence, whereas sirtinol, an inhibitor of SIRT1, exerted the opposite. Taken together, these results indicated that whey protein-mediated upregulation of SIRT1 exerts an anti-senescence effect, and can thus ameliorate Ang II-induced vascular aging as a dietary supplement.

• 한국축산식품학회지
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• 제35권3호
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• pp.350-359
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• 2015

This review focuses on the enhanced functional characteristics of enzymatic hydrolysates of whey proteins (WPHs) in food applications compared to intact whey proteins (WPs). WPs are applied in foods as whey protein concentrates (WPCs), whey protein isolates (WPIs), and WPHs. WPs are byproducts of cheese production, used in a wide range of food applications due to their nutritional validity, functional activities, and cost effectiveness. Enzymatic hydrolysis yields improved functional and nutritional benefits in contrast to heat denaturation or native applications. WPHs improve solubility over a wide range of pH, create viscosity through water binding, and promote cohesion, adhesion, and elasticity. WPHs form stronger but more flexible edible films than WPC or WPI. WPHs enhance emulsification, bind fat, and facilitate whipping, compared to intact WPs. Extensive hydrolyzed WPHs with proper heat applications are the best emulsifiers and addition of polysaccharides improves the emulsification ability of WPHs. Also, WPHs improve the sensorial properties like color, flavor, and texture but impart a bitter taste in case where extensive hydrolysis (degree of hydrolysis greater than 8%). It is important to consider the type of enzyme, hydrolysis conditions, and WPHs production method based on the nature of food application.