Thermal tolerance of acid-adapted and unadapted Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes in cantaloupe juice and watermelon juice.
OBJECTIVE
A study was performed to determine D values of acid-adapted and unadapted cells of Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes in cantaloupe juice and watermelon juice.


RESULTS
Salmonella enterica serotype Poona, S. enterica serotype Saphra, two strains of E. coli O157:H7, and two strains of L. monocytogenes were grown in tryptic soy broth (TSB) and TSB supplemented with 1% glucose for 24 h at 37 degrees C. Decimal reduction times (D values) of cells suspended in unpasteurized cantaloupe juice and watermelon juice were determined. Acid-adapted cells of Salmonella and E. coli O157:H7, but not L. monocytogenes, had increased thermal tolerance compared with cells that were not acid-adapted. There was no correlation between soluble solids content of the two types of juice and thermal resistance.


CONCLUSIONS
Growth of Salmonella and E. coli O157:H7 in cantaloupe juice, watermelon juice, or other acidic milieu, either in preharvest or postharvest environments, may result in cross protection to heat. The pasteurization conditions necessary to achieve elimination of pathogens from these juices would consequently have to be more severe if cells are habituated to acidic environments.


CONCLUSIONS
Insights from this study provide guidance to developing pasteurization processes to eliminate Salmonella, E. coli O157:H7, and L. monocytogenes in cantaloupe juice and watermelon juice.
Sharma
M
M
Center for Food Safety and Department of Food Science and Technology, University of Georgia, Griffin, 30223, USA.
Adler
B B
BB
Harrison
M D
MD
Beuchat
L R
LR
D000222:Adaptation, Physiological; D029773:Citrullus / Q000737:chemistry*; D028463:Cucumis melo / Q000737:chemistry*; D019453:Escherichia coli O157 / Q000254:growth & development / Q000502:physiology*; D005516:Food Microbiology; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008089:Listeria monocytogenes / Q000254:growth & development / Q000502:physiology*; D012486:Salmonella typhimurium / Q000254:growth & development / Q000502:physiology*