http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
우유의 열처리가 우유품질과 영양가에 미치는 영향: Ⅲ. 우유 열처리에 의한 병원균 사멸효과
문용일 ( Yong-ii Moon ),정지윤 ( Ji Yun Jung ),오세종 ( Sejong Oh ) 한국유가공기술과학회 2017 Journal of Dairy Science and Biotechnology (JMSB) Vol.35 No.2
heat-treatments for milk sold in retail markets are pasteurization (LTLT, low-temperature long time; HTST, high-temperature short time) and sterilization (UHT, ultra-high temperature). These treatments extend the shelf life of milk. The main purpose of heat treatment is to reduce pathogenic and perishable microbial populations, inactivate enzymes, and minimize chemical reactions and physical changes. Milk UHT processing combined with aseptic packaging has been introduced to produce shelf-stable products with less chemical damage than sterile milk in containers. Two basic principles of UHT treatment distinguish this method from in-container sterilization. First, for the same germicidal effect, HTST treatments (as in UHT) use less chemicals than cold-long treatment (as in in-container sterilization). This is because Q10, the relative change in the reaction rate with a temperature change of 10°C, is lower than the chemical change during bacterial killing. Based on Q10 values of 3 and 10, the chemical change at 145°C for the same germicidal effect is only 2.7% at 115°C. The second principle is that the need to inactivate thermophilic bacterial spores (Bacillus cereus and Clostridium perfringens, etc.) determines the minimum time and temperature, while determining the maximum time and temperature at which undesirable chemical changes such as undesirable flavors, color changes, and vitamin breakdown should be minimized.
이봄이 ( Bomee Lee ),이해창 ( Hae-chang Yi ),문용일 ( Yong-ii Moon ),오세종 ( Sejong Oh ) 한국유가공기술과학회 2018 Journal of Dairy Science and Biotechnology (JMSB) Vol.36 No.3
Kefir, which originates in the Caucasian mountains, is a cultured milk beverage produced by a combination of acidic and alcoholic fermentation. Kefir products are commonly used as food vehicles to deliver health-promoting materials including kefran and lactic acid bacteria to consumers. The aim of this study was to develop a freeze-dried starter culture without yeast and assess the suitability of kefir-like dairy products for the growth of lactic acid bacteria and the acidification of milk. Pasteurized whole milk (SNF 8.5%) stored at 25℃ was aseptically inoculated with starter cultures (0.002% w/v); it was kept at 25℃ until the pH attained a value of 4.6. Ten grams of the kefir-like product sample was diluted with 90 mL of 0.15% peptone water diluent in a milk dilution bottle, followed by uniform mixing for 1 min. Viable cells of Lactobacillus species were enumerated on modified-MRS agar (pH 5.2), with incubation at 37℃ for 48 h. Viable cells of Lactococcus species were enumerated on M17-lactose agar, with incubation at 32℃ for 48 h. The pH attained a value of 4.6 after fermentation for 9 h 30 min (Starter 1), 9 h 45 min (Starter 2), and 12 h (Starter 3). The viable cell count of Lactobacillus sp. and Lactococcus sp. was initially 10<sup>5</sup>∼10<sup>6</sup> CFU/g; it increased significantly to 10<sup>9</sup> CFU/g after 12 h of incubation. During the storage of the kefir-like products at 4℃ for 1 4 days, the total viable cell numbers were unchanged, but the pH decreased slightly. The consistency of the kefir products increased gradually during the storage. The organoleptic properties of the kefir products fermented using the new starter culture are more desirable than those of commercial kefir. These results suggest that the newly developed starter culture without yeast could be suitable for kefir fermentation.