Heat resistance of Escherichia coli O157:H7 in apple juice.
The objective was to determine the effect of cider composition on the heat resistance of Escherichia coli O157:H7. The average D52 value in a model Empire apple juice was 18 min with a z value of 4.8 degrees C. Increasing the Brix from 11.8 to 16.5 degrees had no effect on thermal resistance, while increasing L-malic acid from 0.2 to 0.8%, or reducing the pH from 4.4 to 3.6 sensitized the cells to heat. The greatest effect on heat resistance was afforded by the preservatives benzoic and sorbic acids: D50 values in ciders containing 1,000 mg/l were 5.2 min in the presence of sorbic acid and only 0.64 min in the presence of benzoic acid. Commercial apple juice concentrates yielded lower numbers of survivors than single-strength juices even though their higher sugar concentrations of about 46 degrees Brix increased heat resistance.
Splittstoesser
D F
DF
Department of Food Science and Technology, Cornell University, Geneva, New York 14456, USA.
McLellan
M R
MR
Churey
J J
JJ
D019817:Benzoic Acid / Q000494:pharmacology; D001628:Beverages / Q000382:microbiology*; D015169:Colony Count, Microbial; D019453:Escherichia coli O157 / Q000254:growth & development* / Q000302:isolation & purification; D005511:Food Handling / Q000379:methods*; D005520:Food Preservatives / Q000494:pharmacology; D006358:Hot Temperature; D006801:Humans; D019685:Rosales; D013011:Sorbic Acid / Q000494:pharmacology
D005520:Food Preservatives; D019817:Benzoic Acid; D013011:Sorbic Acid