• Title, Summary, Keyword: psychrotrophic counts

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A Study on the Deterioration of Raw Milk Quality by the Growth of Psychrotrophic Bacteria (원유의 저온성 세균의 증식에 의한 유질변화에 관한연구)

  • 정충일;강국희;이재영
    • Journal of Food Hygiene and Safety
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    • v.1 no.2
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    • pp.151-156
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    • 1986
  • A trial was carried out to check the seasonal variation in total bacterial counts (T.B.C.) and psychrotrophic bacterial counts (P.B.C.) and to investigate the quality deterioration of raw milk collected from dairy farms in Kyunggi area, Korea. T.B.C. of raw milk exceeded $10^{7}/ml$ in summer and $10^{6}/ml$ in winter 1980, but they have gradually decreased from 1983. In 1985, the counts showed less than $2{\times}10^{6}/ml$ through the whole year. The same tendency of improvement in coliform counts was shown. The counts were higher than $10^{6}/ml$ in summer and $10^{5}/ml$ in winter 1982, but they were kept lower than $1{\times}10^{5}/ml$ in 1985 through the whole year. Free fatty acids and free amino acids were increased in raw milk stored at $5^{\circ}C\;and\;10^{\circ}C$, by the growth of psychrotrophic bacteria.

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A Study on the Microbiological Quality of Raw Milk in the North of Kyeongnam Area (경남 북부지역 납유원유의 미생물학적 품질에 관한 연구)

  • 이국천;손성기;안동원
    • Korean Journal of Veterinary Service
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    • v.13 no.1
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    • pp.27-31
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    • 1990
  • This study was carried out to obtain basic data for the Improvement of microbiological quality of raw milk. Total bacterial, psychrotrophic, thermoduric and spore counts of raw milk samples taken from milk tankers in the nothern part of kyeongnam were investigated for one year from March, 1989. The result obtained were summarized as follow 1. The number of total bacteria in raw milk averaged $4.0{\times}10^6$ CFU / ml and was not affected by seasons 2. The psychrotrophic counts of raw milk averaged $1.5{\times}10^6$ CFU / ml and it was higher in winter than in summer 3. The thermoduric counts of raw milk averaged $5.8{\times}10^4$ CFU / ml and was the lowest in winter 4. The spore counts of raw milk ranging from 3-1, 880/ ml averaged 306/ ml and was the lowest in summer

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Effect of Gamma Irradiation on the Microflora of Commercial Ready-To-Use (RTU) Salads during Cold Storage

  • Kim, Jang-Ho;Lee, Ju-Woon;Lee, You-Seok;Oh, Sang-Hee;Byun, Myung-Woo
    • Preventive Nutrition and Food Science
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    • v.9 no.3
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    • pp.232-235
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    • 2004
  • Since ready-to-use (RTU) products are not fully cooked, the shelf-life of the product is comparably short and the products are easily spoiled when contaminated with food-borne pathogens. Low-dose gamma irradiation of 0.5, 1, or 2 kGy effectively reduced the total aerobic bacterial counts in 2 Korean manufactured RTU products by 1.63 to 2.95 log CFU/g during cold storage. Irradiation at 2 kGy reduced the psychrotrophic bacterial counts in most of the samples to below the limit of detection (< log CFU/g). Irradiation at 0.5 kGy completely eliminated Escherichia coli from the commercial RTU samples.

Effects of Psychrotrophic Bacteria, Serratia liquefaciens and Acinetobacter genomospecies 10 on Yogurt Quality

  • Shin, Yong Kook;Oh, Nam Su;Lee, Hyun Ah;Choi, Jong-Woo;Nam, Myoung Soo
    • Food Science of Animal Resources
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    • v.34 no.4
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    • pp.543-551
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    • 2014
  • The aim of this study was to evaluate the effect of proteolytic (Serratia liquefaciens, match %: 99.39) or lipolytic (Acinetobacter genomospecies 10, match %: 99.90) psychrotrophic bacteria (bacterial counts, analysis of free fatty acids (FFA) and analysis of free amino acids) on the microbial and chemical properties (yogurt composition), and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of yogurt during storage. Yogurts were prepared with raw milk preinoculated with each psychrotrophic bacteria. The total solid, fat, and protein content were not affected by preinoculation, but the pH of yogurt preinoculated with psychrotrophic bacteria was higher than in control. There was a dramatic increase in short chain free fatty acids among FFA in yogurt with Acinetobacter genomospecies 10. For 14 d of cold storage condition, SCFFA was 25.3 mg/kg to 34.4 mg/kg (1.36 times increased), MCFFA was 20.4 mg/kg to 25.7 mg/kg (1.26 times increased), and LCFFA was 240.2 mg/kg to 322.8 mg/kg (1.34 times increased). Serratia liquefaciens (match %: 99.39) in yogurt caused a greater accumulation of free amino acids (FAA), especially bitter peptides such as leucine, valine, arginine, and tyrosine, but SDS-PAGE showed that the inoculation of Serratia liquefaciens did not affect the degree of casein degradation during storage. Taken together, the excessive peptides and FFA in yogurt generated from psychrotrophic bacteria could develop off-flavors that degrade the quality of commercial yogurt products.

The Conductance Determination of Total, Coliform and Psychrotrophic bacteria Counts in Raw Milk by Using Malthus (Malthus를 이용한 원유(原乳)내의 총균수, 대장균군수, 저온성균수 측정)

  • Nam, Eun-Sook;Chung, Choong-Il;Kang, Kook-Hee;Jeong, Dong-Kwan
    • Korean Journal of Food Science and Technology
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    • v.26 no.6
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    • pp.764-769
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    • 1994
  • This study was performed to obtain fast, consistant and reliable estimation system of bacterial counts of raw milk, which effectively related to the quality of sanitaion and the condition of production at the farm. This study compared regression equation and correlation coefficient relationship between standard plate counts and data of Malthus conductance method for the detection time of total, psychrotrophs, coliform bacterial counts in raw milk. Regression equation (RE) between conductance detection time (Y) and total bacterial log counts (X) was Y=18.27651 - 2.07550X, with correlation coefficient -0.95(n=201). In coliform, RE was Y=9.320848 - 1.15598X with correlation coefficient -0.90 (n=207). Psychrotrophs had the RE of Y=29.96008-3.02487 with correlation coeffecient -0.9 (n=201). This conductance method gave results more quickly and was less labor-intensive than traditional standard plate count method.

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Development of Hydrogels to Improve the Safety of Yukhoe (Korean Beef Tartare) by Reducing Psychrotrophic Listeria monocytogenes Cell Counts on Raw Beef Surface

  • Oh, Hyemin;Kim, Sejeong;Lee, Soomin;Ha, Jimyeong;Lee, Jeeyeon;Choi, Yukyung;Lee, Yewon;Kim, Yujin;Seo, Yeongeun;Yoon, Yohan
    • Food Science of Animal Resources
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    • v.38 no.6
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    • pp.1189-1195
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    • 2018
  • This study developed an antimicrobial hydrogel to control Listeria monocytogenes in Yukhoe (Korean beef tartare). Four hydrogels (hydrogel 1: 5% alginate+1% chitosan+0.2% $CaCl_2$, hydrogel 2: 1% ${\kappa}$-carrageenan+1% chitosan, hydrogel 3: 2% ${\kappa}$-carrageenan+1% $CaCl_2$, and hydrogel 4: 2% ${\kappa}$-carrageenan+3% $CaCl_2$) were prepared. The hydrogels then absorbed 0.1% grapefruit seed extract (GSE) and 0.1% citrus extract (CE) for 30, 60, 120, and 240 min to be antimicrobial hydrogels. To select the most effective antimicrobial hydrogel, their swelling ratio (SR) and antilisterial activities were determined. The selected hydrogel ($2{\times}2cm$) was then placed on surface of beef (round; $3{\times}3cm$), where L. monocytogenes (ca. $10^6CFU/g$) were inoculated, and the cell counts were enumerated on PALCAM agar. Among the hydrogels, the SR of hydrogel 1 increased with absorbing time, but other hydrogels showed no significant changes. Antimicrobial hydrogel 1 showed higher (p<0.05) antilisterial activity than other antimicrobial hydrogels, especially for the one absorbed the antimicrobial for 120 min. Thus, the antimicrobial hydrogel 1 absorbed antimicrobials for 120 min was applied on raw beef at $4^{\circ}C$, and reduced (p<0.05) more than 90% of L. monocytogenes on raw beef. These results indicate that antimicrobial hydrogel 1 formulated with 0.1% GSE or 0.1% CE is appropriate to improve the safety of Yukhoe by reducing psychrotrophic L. monocytogenes cell counts on raw beef.

Effect of Tenderizer on Physical Quality and Microbial Safety during Korean Beef Jerky Production (한국형 우육포의 제조공정 중 연화제가 육포품질 및 미생물학적 안전성에 미치는 영향)

  • Kim, Hyoun-Wook;Han, Doo-Joung;Kim, Cheon-Jei;Paik, Hyun-Dong
    • Food Science of Animal Resources
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    • v.28 no.5
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    • pp.675-680
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    • 2008
  • The physical quality and microbial safety of Korean beef jerky was evaluated at various steps during its preparation. Microbial counts in raw beef demonstrated mesophillic bacteria at 4.20 Log CFU/g, psychrotrophic bacteria at 3.85 Log CFU/g, anaerobic bacteria at 4.90 Log CFU/g, and yeast and molds at 1.92 Log CFU/g. Spore-forming bacteria and coliforms were not detected in raw beef samples. Spices and spiced meats showed similar trends in microbial counts, demonstrating minimal microbial contamination during these stages of preparation. The final beef jerky product exhibited counts of mesophillic bacteria at 1.15-1.66 Log CFU/g, psychrotrophic bacteria at 1.15-1.66 Log CFU/g, and anaerobic bacteria at 0.81-1.72 Log CFU/g. Spore-forming bacteria, yeast and molds, and coliforms were not detected in beef jerky. Significant differences from added ingredients occurred for instron textural profile analysis traits for hardness. In general, Korean beef jerky with humectant and tenderizer had lower hardness than control (without humectant and tenderizer). Also, the sample added with 0.01% protease from Streptomyces griseus had lower hardness than all samples. All samples had 0.7l to 0.72 water activities, and the color and pH were not shown in significant changes of all samples.

Applying the Disinfecting Effects of Vinegar to Raw Vegetables in Foodservice Operations: A Focused Microbiological Quality Evaluation (급식소에서 이용되는 채소류의 식초수 소독의 적용을 위한 연구 - 미생물적 품질 평가를 중심으로 -)

  • Kim, Hyun-Jung;Kim, Heh-Young;Ko, Sung-Hee
    • Korean journal of food and cookery science
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    • v.23 no.4
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    • pp.567-578
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    • 2007
  • This study was designed to provide basic data for the application and practical use of vinegar disinfection for raw vegetable preparation in foodservice operations. The test materials were washed and disinfected by three different methods(tap water washing, chlorine water disinfection, vinegar disinfection) and stored at $3^{\circ}C$ and $10^{\circ}C$ for 7 days. Then, their microbiological qualities were compared. Total plate counts increased over the course of the storage period, and all samples, except in the case of tap water washing, remained under the permitted limit until the 7th day of storage. In particular, vinegar disinfection showed the lowest increase in total plate counts(2.35${\sim}$4.03 log CFU/g). While the total plate counts of chlorine and vinegar disinfection were within the 6.00 limit of microbiological safety, the tap water washing treatment passed the permitted limit. The psychrotrophic counts increased steadily over the course of the storage period, and increased least at $3^{\circ}C$, however, the tap water washing showed the most drastic increase, while vinegar disinfection yielded the smallest increase.

Studies on Extending the Shelf-life of Refrigerated Chicken 1. Effects of Potassium Sorbate and/or Ascorbic Acid Dip on Microbial and Sensory Quality of Refrigerated Chicken (냉장 닭고기의 저장성 연장에 관한 연구 1. Potassium Sorbate와 Ascorbic Acid 처리가 닭고기의 미생물 및 관능적 품질에 미치는 영향)

  • 유익종
    • Korean Journal of Poultry Science
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    • v.17 no.2
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    • pp.115-122
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    • 1990
  • Effects of 7.5% potassium sorbate and/or 1% ascorbic acid dip on she]f-life of chicken parts stored at $4^{\circ}C$ was investigated. There was no remarkable difference in the microbial growth between 1% ascorbic acid dipped chicken parts and untreated chicken parts. Off-odor developed after 8 days storage and bacterial spoilage was occurred after 12 days storage. 7.5% potassium sorbate dip significantly retarded mesophilic and psychrotrophic counts compared with untreated, markedly reduced growth rate of Enterobacteriaceae. Fecal coliforms were not detected and bacterial spoilage was not occurred until 21 days storage. off-odor developed after 19 days storage and color was not significantly deteriorated until 21 days storage. Additional effect of 7.5% potassium sorbate and 1% ascorbic acid dip was found on retarded mesophilic, psychrotrophic and Enterobacteriaceae counts compared with 7.5% potassium sorbate dip alone. Bacterial spoilage was not occurred until 21 days storage. off-odor developed after 21 days storage and color was not significantly deteriorated until 21 dayss storage.

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Identification of Coliform Bacteria Isolated from Nangmyun-Broth in Korea and Psychrotrophic Character (냉면육수에서 분리한 대장균군의 동정 및 저온 증식성)

  • O, Myeong-Hwan;Kim, Mi-Yeong;Lee, Jin-Yeong
    • The Korean Journal of Food And Nutrition
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    • v.7 no.3
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    • pp.203-212
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    • 1994
  • The nangmyun is a Korean iced noodle made by putting buckwheat-noodles into cold broth. Seven samples of nangmyun-broths were collected from Korean restaurants in Bucheon during July 1994. The contamination levels of nangmyun-broths by coliform bacteria were determined, and then the 40 colonies of coliform bacteria, isolated randomly from 4 samples of nangmyun-broths, were identified at genus or species level with the additional test for psychrotrophic character The coliform counts in nangmyun-broths were 6.0x102-6.5$\times$104/ml(average 2.3$\times$104%). Among the 40 strains of isolates, 27 strains(67.5%) were identified as the genus Klebsiella, 9 strains(22.5%) as the genus Enterobacter, 2 strains(5.0%) as the genus Citrobacter and 2 strains (5.0%) as the genus Escherichia. Among 27 strains of Klebsiella, 11 strains (40.8%) were identified as K planticola, 4 strains(14.8%) as K. pneumoniae, 2 strains(7.4%) as K. ozaenae and 2 strains(7.4%) as K. terrigena, but 8 strains(29.6%) of a typic\ulcorner1 Klebgiella could not be Identified at species level. All the 40 strains of coliform bacteria were psychrotrophs showing slow growth at 1$0^{\circ}C$, and 18 strains(45%) grew at 5$^{\circ}C$. It was thought to be a good basic data In describing the reason for too high coliform counts in nangmyun-broths that all coliform bacteria tested In this study were psychrotrophs.

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