Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 16, 2000
Publication Date: July 17, 2000
Interpretive Summary: Unpasteurized apple cider has been associated with food borne disease caused by E. coli O157:H7 bacteria several times in the past decade. This organism can cause serious illness in adults, and is a primary cause of kidney failure in children. As a result of the association of unpasteurized apple cider with illness, the Food and Drug Administration has mandated that processors either include a warning label on their product, or develop a Hazard Analysis Critical Control Point (HACCP) plan, a system by which a reduction of 99.999% in the numbers of potentially harmful organisms is guaranteed in the finished product. This study has identified a potential source of E. coli O157:H7 contamination. We have shown that E. coli O157:H7 numbers can increase by 1000 fold in apples decayed by Glomerella cingulata fungal growth. The results suggest that the exclusion of decayed apples from the production of unpasteurized apple cider is a valid addition to a HACCP plan, and should be of particular interest to processors who have a G. cingulata problem in their orchards.
Technical Abstract: The survival of Escherichia coli O157:H7 in the presence of one of two plant pathogens, Penicillium expansum and Glomerella cingulata, in wounds on apples were observed during 14 d storage at room temperature (RT) and at 4 degrees Celsius. The aim of this work was to determine if changes in apple physiology caused by the proliferation of fungal decay organisms would foster the survival of E. coli O157:H7. Trials were performed where (A) plant pathogens (4 log) were added to apple wounds 4 d before the wounds were inoculated with E. coli O157:H7 (3 log), (B) plant pathogens and E. coli O157:H7 were added on the same day and (C) E. coli O157:H7 was added 2 d (RT) and 4 d (4 degrees Celsius) before plant pathogens. In all trials E. coli O157:H7 levels generally declined to less than 1 log at 4 degrees Celsius storage, and in the presence of P. expansum at 4 degrees Celsius or RT. However, in the presence of G. cingulata at RT, E. coli O157:H7 numbers increased from 3.18 to 4.03 log cfu per g in the apple wound during Trial A, from 3.26 to 6.31 log cfu per g during Trial B, and from 3.22 to 6.81 log cfu per g during Trial C. This effect is probably a consequence of the attendant rise in pH from 4.1 to approx. 6.8, observed with the proliferation of G. cingulata rot. Control apples (inoculated with E. coli O157:H7 only) were contaminated with opportunistic decay organisms at RT during Trials A and B, leading to E. coli O157:H7 death. However, E. coli O157:H7 in control apples in Trial C (no contamination) increased from 3.22 to 5.97 log cfu per g. The fact that E. coli O157:H7 can proliferate in areas of decay and/or injury on fruit highlights the hazards associated with the use of such fruit in the production of unpasteurized juice.