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오남수,신용국,백승천,Oh, N.S.,Shin, Y.K.,Baick, S.C. 한국축산식품학회 2009 한국축산식품학회지 Vol.29 No.4
The aim of this study was to optimize a simple, fast, and economical analysis procedure for the determination of 16 different pesticides in raw milk via GC/MSD. Analyses were performed via gas chromatography with electron impact mass spectrometric detection in the selected ion monitoring mode (GC/MSD-SIM) using Pentachloronitrobenzene as the internal standard. The modified sample preparation methodology was based on the Pesticide Analytical Manual (PAM) of the FDA concerning fat extraction, ACN-ether partitioning, and clean-up of the Sep-Pak florisil cartridge. The modified methodology for the determination of the 16 pesticides was validated. The range of LOQs of the 16 pesticides was likely three times lower than their Maximum Residence Levels (MRLs). The recoveries of most of the pesticides were acceptable at the fortification levels of 0.5 and 1.0 ${\mu}g/mL$ and their RSD (%) level was less than 20%. None of the 16 pesticides were detected in the selected raw milk samples.
백승천 한국유가공기술과학회 2000 한국유가공기술과학회지 Vol.18 No.2
The Codex Alimentarius system, international food code, has become the global reference point for consumers, food producers and processors, national food control agencies and especially for the international food trade. As many people understand, the essential Codex purpose may be the protection of consumer health. The Codex Committee on Milk and Milk Products(CCMMP) program is one of many other subsidiary committees. At the 4th session of CCMMP which was held in New Zealand this year, totally 9 agenda items were discussed. The most important and hottest item was the filled milk or filled products to justify Codex standards. Our delegations refused the proposed draft as to classify these products for protection of nation dairy farmers and industry. This agenda item will be discussed again next session by supporting some international organization including IDF. The heat treatments definition, classification of cheese products, fermented milk standards by its type were also discussed. In the standpoint of our nation profits, we need to communicate well other countries or international organizations with very specialized persons.
HPLC 를 이용한 우유내 비타민 D2 및 D3 의 정량분석에 관한 연구
백승천,김철현,정운현,하영식 한국동물자원과학회 2001 한국축산학회지 Vol.43 No.1
This study was carried out to compare three HPLC column and various mobile phase for the determination of vitamin D₂and D₃in milk. The saponified samples were extracted with hexane, and the extracts containing interfering substances were further clean up by using the Sep-pak cartridge containing silica. The Symmetry C_(18) column provided more satisfactory analysis data than the other columns in terms of precision and selectivity. The Symmetry C_(18) column showed a linear relationship between the concentration increments and peak areas of in vitamin D₂and D₃in the standard solution(r=0.998∼999, P$lt;0.01). The recovery percent(97.10∼99.78%) of vitamin D₃ in the samples saponified and extracted were much higher than those(51.90∼80.96%) in the samples only clean-up treated.(51.90∼80.96%).
백승천,정운현 한국동물자원과학회 2000 한국축산학회지 Vol.42 No.2
Attached microorganisms, which may be causing biofilms, can be a serious problem in the food processing industry especially in dairy food industry. Within the biofilm, the bacteria are continually growing, multiplying, and being released into environment. This could be an important source of subsequent product contamination. Because both pathogenic and spoilage bacteria have been shown to attach to the surfaces commonly used in dairy processing, their presence should not be overlooked. Primary attachment between bacteria and surfaces occurs reversibly through surface charges, Van der Waals forces, and hydrophobic interactions. Prevention is the key to discouraging biofilm build-up. Once biofilms are firmly established, cleaning and sanitizing becomes much more difficult. The sanitizers are unable to penetrate the glycocalyx matrix and contact the bacteria cells in order to destroy biofilms. Bacteria are less likely to survive the sanitation procedures if the surface has been properly cleaned and the sanitizer is applied in the proper concentration at the appropriate temperature and pH.
유산균에 의한 Escherichia coli 와 Salmonella typhimurium 의 생육억제에 관한 연구
김은아,백승천,정운현 한국동물자원과학회 2002 한국축산학회지 Vol.44 No.4
본 실험에서는 lactobacilli와 bifidobacteria에 의한 E. coli와 S. typhimurium에 대한 생육 억제능을 조사 하였다. 생육억제활성은 well disc assay와 turbidimetry method로 측정하여 비교하였다. 시험균주 10종 중에서 두 가지 방법 모두 평균적으로 높은 항균 활성을 나타낸 균주는 L. acidophilus La-5, L. acidophilus NCFM와 L. casei Lc-01인 것으로 나타났다. 선택된 3가지 유산균과 대표적 enteropathogen인 E. coli와 S. typhimurium을 각각의 혼합 배양하여 생균수를 측정한 결과 병원성균 생육억제는 생균수가 급격히 감소하는 배양 9시간 이후부터 나타났으며 30시간 혼합배양 후에는 병원성균의 생균수는 거의 존재하지 않았다. 실험결과 유산균의 항균활성은 pH 저하 만에 의한 것이 아니었고 유산균의 종류에 따라 생육억제활성에 차이가 있었다. The inhibitory effect of lactobacilli and bifidobacteria on the growth of typical intestinal pathogens, Escherichia coli and Salmonella typhimurium was studied. The degree of inhibition was measured by well disc assy and turbidimetry method. The strains which showed the higher antimicrobial activity were L. acidophilus La-5, L. acidophilus NCFM, L. casei Lc-01 on the average by using two different methods. The associative cultures were performed with selected 3 lactobacilli and. 2 enteropathogens E. coli and S. typhimurium, respectively. Inhibition of pathogen began at 9hr after culturing so that viable counts was decreased rapidly. After 30hr incubation, there were no viable pathogens from the mixed culture. Under this experimental condition, the antimicrobial activity of lactic acid bacteria was not due to pH alone and supposed to different to the strains.