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      • HARVEST
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      HEAT RESISTANCE OF BACTERIA IN ALCOHOL-FREE BEER

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      L'Anthoen_Nancy_Chabot_1995_sec.pdf (4.072Mb)
      Date
      1995
      Author
      L'Anthoën, Nancy Chabot
      Type
      Thesis
      Degree Level
      Masters
      Metadata
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      Abstract
      Two of the most heat resistant beer spoilage organisms found to date, Pediococcus acidilactici and Lactobacillus delbrueckii, and two human pathogens, Escherichia coli 0157:H7 and Salmonella typhimurium (both recently associated with outbreaks of diarrhea and hemolyticuremic syndromein apple cider), were tested for heat resistance in commercial alcohol-free beer and commercial 5% alcohol beer. Using the attemperated dilution blank adaption of the multiple point method, known cell concentrations were inoculated into 5% alcohol beer and alcohol-free beer held at a variety of heating temperatures. Survival curves, D values, phantomthermal death time curves, and Z values were determined. Decimal reduction times at 600C (D6o), a common temperature for beer pasteurization, were obtained by extrapolation. Pathogens demonstrated 3 to 17 times more heat resistance in alcohol-free beer and both lactic acid bacteria showed an increased resistance to heat of 4 to 7 fold in alcohol-free beer compared to 5% alcohol beer. Results illustrated a significant difference in the pasteurization parameters required to achieve microbiological stability of alcohol-free beers compared to 5% alcohol beer. Although pathogens tested are not at all heat resistant, and do not survive pasteurization temperatures even over short time intervals, these organisms can grow in alcohol-free beer and industry is cautioned about the safety and sale of unpasteurized low alcohol products when processed by filtration.
      Degree
      Master of Science (M.Sc.)
      Department
      Food and Bioproduct Sciences
      Program
      Applied Microbiology and Food Science
      Supervisor
      Ingledew, W. M.
      Copyright Date
      Fall 1995
      URI
      http://hdl.handle.net/10388/11944
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      • Graduate Theses and Dissertations
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