Combined effects of water activity, temperature and chemical treatments on the survival of Salmonella and Escherichia coli O157:H7 on alfalfa seeds.
OBJECTIVE
The objective of this study was to determine the combined effects of water activity (a(w)), chemical treatment and temperature on Salmonella and Escherichia coli O157:H7 inoculated onto alfalfa seeds.


RESULTS
Alfalfa seeds inoculated with Salmonella or E. coli O157:H7 and adjusted to various a(w) values were subjected to simultaneous and separate treatments with chemicals and heat. The rate of death of both pathogens was correlated with increased a(w) (0.15-0.60) and temperature (5-37 degrees C) over a 52-week storage period. Higher seed a(w) enhanced the inactivation of pathogens on seeds heated at 50-70 degrees C for up to 24 h. Treatment of seeds with water, 1% Ca(OH)2, 1% Tween 80, 1% Ca(OH)2 plus 1% Tween 80 or 40 mg l(-1) Tsunami 200 at 23 or 55 degrees C for 2 min significantly (alpha=0.05) reduced populations of Salmonella and E. coli O157:H7.


CONCLUSIONS
Overall, at the combinations of temperature and concentrations of chemicals tested, 1% Ca(OH)2 was most effective in killing Salmonella and E. coli O157:H7 without reducing seed viability.


CONCLUSIONS
None of the treatments evaluated in this study, whether applied separately or in combination, eliminated Salmonella or E. coli O157:H7 on alfalfa seeds without sacrificing the viability of the seeds. It remains essential that practices to prevent the contamination of alfalfa seeds be strictly followed in order to minimize the risk of Salmonella and E. coli O157:H7 infections associated with sprouts produced from these seeds.
Beuchat
L R
LR
Department of Food Science and Technology, Center for Food Safety, University of Georgia, 1109 Experiment Street, Griffin, GA 30223-1797, USA. lbeuchat@cfs.griffin.peachnet.edu
Scouten
A J
AJ
D002126:Calcium Hydroxide / Q000494:pharmacology; D004202:Disinfectants / Q000494:pharmacology; D004203:Disinfection / Q000379:methods*; D019453:Escherichia coli O157 / Q000187:drug effects / Q000254:growth & development*; D018525:Germination; D006358:Hot Temperature; D000455:Medicago sativa / Q000382:microbiology*; D011136:Polysorbates / Q000494:pharmacology; D012475:Salmonella / Q000187:drug effects / Q000254:growth & development*; D012639:Seeds / Q000382:microbiology*; D013696:Temperature; D014867:Water
D004202:Disinfectants; D011136:Polysorbates; D014867:Water; D002126:Calcium Hydroxide