• 식품과학과 산업
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• 제53권3호
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• pp.256-263
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• 2020

Milk pasteurization is used to destroy harmful bacteria present in the raw milk for improvement of the keeping quality of dairy products. It is generally carried out in dairy industries as the heating process of raw milk in properly designed and operated equipment to a specific temperature for a specified a specified period. However, thermal processing may cause quality changes in milk as well as significant nutritional losses. Hence, many researchers have started work to design alternative strategies to produce safer foods with minimal thermal treatments for pasteurization. Therefore, the present paper shows the current status of commercial pasteurization system of dairy products in korean industry and the research efforts carried out by researchers on novel milk pasteurization system that could be an alternative to traditional thermal processes for maintaining the freshness of dairy products.

• Journal of Dairy Science and Biotechnology
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• 제33권3호
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• pp.223-229
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• 2015

Milk is a food with high nutritional value as it contains abundant water, proteins, vitamins, lactose, fat, minerals, enzymes, etc. However, in order to make milk suitable for intake, it should be thermally treated to eliminate microbiologically hazardous factors. Heat treatment is an essential sanitation process for milk, but various precautions must be taken in order to process and preserve it. Therefore, various techniques should be developed to minimize the nutrient loss and to ensure that milk is safe for consumption, conservation, and distribution. However, the existing thermal pasteurization methods are harmful and increase the nutrient loss; moreover, no new thermal pasteurization methods are being researched that are safe for the human health and minimize the nutrient loss. Hence, this study aims to review new processes for thermal (low temperatures) and no thermal pasteurization methods that can minimize the nutrient loss during milk pasteurization.

• Journal of Dairy Science and Biotechnology
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• 제32권1호
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• pp.31-36
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• 2014

Thermal pasteurization has been effectively used for decades as a method to extend the shelf life of milk and to inactivate any pathogenic bacteria that it may contain; however, it can negatively affect the nutritional properties of milk. In recent years, the food industry has sought new, less aggressive technologies that affect food freshness and its nutritive and health benefits less significantly. Various means have been used to extend the shelf life of dairy foods, such as high-pressure processing, irradiation, ohmic heating, and pulsed electric field (PEF) technologies. Of these, PEF technologies are potential alternatives to traditional thermal milk pasteurization, owing to their advantages in minimizing sensory and nutritional damage. In this review, we have primarily focused on the feasibility of applying PEF technologies to the sterilization of dairy products and briefly discussed whether they should be adopted for use in the dairy beverage industry in the future.

• 한국축산식품학회지
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• 제44권6호
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• pp.1453-1461
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• 2024

The presence of cortisol residue in processed dairy milk may be a good parameter for assessing the quality of dairy milk products and an alternative indicator of the overall welfare of dairy cattle. Thus, this study investigated the impact of heat processing on milk cortisol concentration (MCC). In total, 36 milk samples (50 mL) were collected from three Holstein dairy cattle at a research farm over two consecutive days. The samples were divided into experimental groups: unheated, heated at 65℃ for 30 min, and heated at 121℃ for 5 min. Additionally, 11 commercial dairy milk products were purchased under three heating conditions: low temperature, low time (LTLT), ultra-short time (UST), and ultra-high temperature (UHT). MCC was analyzed using an enzyme immunoassay. The average farm MCC (ng/mL) for the unheated milk, milk heated at 65℃, and milk heated at 121℃ were 0.88±0.16, 0.86±0.19, and 0.80±0.15, respectively. MCC was not significantly affected by the heating process. The average market MCC (ng/mL) in LTLT, UST, and UHT were 0.16±0.07, 0.15±0.08, and 0.15±0.07, respectively. Overall, cortisol levels in fresh farm milk were unaffected by the heating process. Monitoring cortisol levels in processed milk could offer a valuable alternative indicator for assessing product quality and animal welfare, particularly when access to raw milk is limited.

• Food Science and Biotechnology
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• 제15권5호
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• pp.756-762
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• 2006

Freeze concentration of milk was carried out through the controlled recrystallization of ice in a multi-stage freeze concentrator. Rheological characteristics of ice slurries were analyzed to determine efficient concentration levels for the freeze concentration process. It was determined that efficient concentration level was 17% of total solids in the first and 27% in the second stage. Physicochemical properties were compared between freeze concentrated and evaporated milk. Freeze concentrated milk was more similar in color appearance to control milk than was evaporated milk. pH significantly decreased in evaporated milk than in freeze concentrated milk. pH of freeze concentrated milk resulted in similar value to control. These results indicated the advantages of freeze concentration as a non-thermal milk processing technology in terms of physicochemical properties. Consequently, we investigated the influence of ice recrystallization on the rheological characteristics of ice slurries and physicochemical properties of freeze concentrated milk.

• 한국식품과학회지
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• 제14권3호
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• pp.276-282
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• 1982

초고온 살균(UHT) 처리와 이에 따른 저장이 우유의 영양가에 미치는 효과에 대하여 토론되었다. 초고온 처리된 우유는 재래의 멸균우유와 비교해 상당히 적은 열 부담을 받는다. 일반적으로 초고온 살균처리 공정중에는 단백질, 지방, 유당, 지용성 비타민과 무기물들의 영양가들은 거의 영향을 받지 않는다. 작은 정도의 수용성 비타민들과 약간의 단백질의 영양가치가 저장중에 손실된다. 우유의 향미와 영양가를 최대한으로 유지하기 위해서는 초고온 살균우유는 냉장온도에 저장되어야 한다고 권장되고 있다.

• 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.

• 한국축산식품학회:학술대회논문집
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• 한국축산식품학회 2005년도 제36차 추계 학술발표대회
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• pp.131-135
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• 2005

In general, the application of HP contributes to improvement of functionalities of meat protein. In the current study, HP allowed the lower thermal processing of restructured meat product. Low thermal processing allowed fresh-like meat color which is one of problems in hot-set restructuring, while they showed slight discolorization induced by HP. In addition, HP processing combined with thermal processing could be achieved the palatable binding strength in restructured meat product. The addition of non-meat protein had an effect in binding strength. However, they showed no effect on water binding properties at 200 MPa, especially in milk proteins such as casein and whey protein. This is probably due to protein aggregation or to increase in surface hydrophobicity under HP. This result indicates that the application of HP on meat restructuring is more significant than the addition of binders. Therefore, the application of HP has apotential benefit in restructured meat product, and further investigations are needed.

• 한국미생물·생명공학회지
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• 제52권2호
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• pp.152-162
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• 2024

The microbial starter used to produce kefir beverages, kefir grain, contains a microbial exopolysaccharide called kefiran. Kefir grain consisting of water-insoluble polysaccharides, proteins, and fats, which can be applied as a multi-functional biopolymer. The mass of kefir grain can increase in the fermentation process of Kefir, but it is considered very slow. The purpose of this research is to study the impact of ammonium sulfate supplementation and yeast extract on reconstituted skim milk to increase the mass kefir grain and physical properties of kefiran. Results showed that the ammonium sulfate-supplemented substrate increased the mass of kefir grain by 547% in 14 days, with the condition that the substrate must be renewed every 2 days. Refreshing the substrate is considered one of the important factors. Supplementation on substrate did not appear to affect the viability of bacterial and yeast cells. Kefir grain produced from supplemented substrate also yields better thermal stability properties and has more functional groups than without supplementation. Two Lacticaseibacillus rhamnosus (RAL27 and RAL43) and one Limosilactobacillus fermentum (RAL29) were found to produce EPS. The three isolates also showed good skim milk fermentation ability after purification from kefir grain. The kefir grain produced in this study has the potential for wider application. This study also showed that kefir grain can be adjusted in quantity and quality through fermentation substrate engineering.

• 한국식품영양과학회지
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• 제45권6호
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• pp.889-893
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• 2016

본 연구에서는 고압처리(high pressure processing) 한 원유를 이용하여 발효유를 제조하고, 발효특성 및 저장 기간 물리 화학적 특성의 변화를 살펴보았다. 고압처리 한 원유를 이용하여 발효유 제조 시 발효 초반에 유산균이 급격히 증식 됨을 확인하였으나, 발효 완료 후 총 유산균 수는 대조군과 크게 차이가 나지 않았다. 저장 기간 중 실험군과 대조군 모두 유산균 수가 서서히 감소하는 경향을 나타내었다. 또한 산도 및 pH는 각 군 모두 정상적인 발효유의 범위를 나타내었다. 각 군의 점도를 대조해 본 결과 대조군이 실험군보다 점도가 높게 나타났으나, syneresis는 450 MPa 처리군이 대조군보다 유의적으로 적게 발생한 것으로 나타났다(P<0.05). 따라서 적절한 압력을 이용한 원유의 고압처리는 발효유의 물성을 개선하는 데 효과가 있다고 할 수 있으며, 이 분야에 관한 연구가 좀 더 이루어져야 할 필요가 있다.