Applied and Environmental Microbiology, May 1999, p. 1924-1929, Vol. 65, No. 5
0099-2240/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Department of Food Science, University of
Wisconsin
Madison, Madison, Wisconsin 53706
Received 11 November 1998/Accepted 10 February 1999
The U.S. Food and Drug Administration (FDA) recently mandated a
warning statement on packaged fruit juices not treated to reduce target
pathogen populations by 5 log10 units. This study describes
combinations of intervention treatments that reduced concentrations of
mixtures of Escherichia coli O157:H7 (strains ATCC 43895, C7927, and USDA-FSIS-380-94) or Salmonella typhimurium DT104 (DT104b, U302, and DT104) by 5 log10 units in apple
cider with a pH of 3.3, 3.7, and 4.1. Treatments used were short-term storage at 4, 25, or 35°C and/or freeze-thawing (48 h at
20°C; 4 h at 4°C) of cider with or without added organic acids (0.1% lactic acid, sorbic acid [SA], or propionic acid). Treatments more
severe than those for S. typhimurium DT104 were always
required to destroy E. coli O157:H7. In pH 3.3 apple cider,
a 5-log10-unit reduction in E. coli O157:H7
cell numbers was achieved by freeze-thawing or 6-h 35°C treatments.
In pH 3.7 cider the 5-log10-unit reduction followed
freeze-thawing combined with either 6 h at 4°C, 2 h at 25°C, or 1 h at 35°C or 6 h at 35°C alone. A
5-log10-unit reduction occurred in pH 4.1 cider after the
following treatments: 6 h at 35°C plus freeze-thawing, SA plus
12 h at 25°C plus freeze-thawing, SA plus 6 h at 35°C,
and SA plus 4 h at 35°C plus freeze-thawing. Yeast and mold
counts did not increase significantly (P < 0.05) during the 6-h storage at 35°C. Cider with no added organic acids treated with either 6 h at 35°C, freeze-thawing or their
combination was always preferred by consumers over pasteurized cider
(P < 0.05). The simple, inexpensive intervention
treatments described in the present work could produce safe apple cider
without pasteurization and would not require the FDA-mandated warning statement.
Madison, 1605 Linden Dr.,
Madison, WI 53706. Phone: (608) 265-4801. Fax: (608) 262-6872. E-mail: scingham{at}facstaff.wisc.edu.
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