FOOD SCIENCE ›› 2010, Vol. 31 ›› Issue (5): 252-255.doi: 10.7506/spkx1002-6300-201005057

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Survival of Escherichia coli O157:H7 in Home-made Yogurt during Storage at 4 ℃

LAI Wei-hua1,2,Daniel Y. C. Fung2,*,Beth Ann Crozier-Dodson2   

  1. 1. State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China;
    2. Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506, US
  • Received:2008-12-31 Online:2010-03-01 Published:2010-12-29
  • Contact: Daniel Y. C. Fung2,*, E-mail:dfung@ksu.edu

Abstract:

In this study, preheated milk was inoculated with 3% (V/V) of plain yogurt and 2.15 (lg(CFU/mL)) of Escherichia coli O157:H7 to carry out the fermentation at 45 ℃ for 5 h. The resulting fermented yogurt was stored at 4 ℃. Samples were processed using Pathatrix, a large volume recirculating immunomagnetic capture system that utilized paramagnetic beads coated with antibody to facilitate the specific capture of E. coli O157: H7 from yogurt. Then the beads were resuspended in 1% peptone solution, spread onto sorbitol-MacConkey agar and incubated at 37 ℃ for 24 h. E. coli O157:H7 exhibited a gradual decrease and could not be detected after 12 days. Therefore, it is necessary for detecting E. coli O157:H7 during the process of manufacture and storage of dairy products.

Key words: Escherichia coli O157:H7, yogurt, Pathatrix system

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