Behavior of Ecoli On Sprouts During Sprouting As Influenced by Treatments with Various Chemicals

Behaviorof Enterohemorrhagic Escherichia coli O157:H7 on Alfalfa Sprouts duringthe Sprouting Process as Influenced by Treatments with Various Chemicals

Journalof Food Protection: Vol. 62, No. 8, pp. 850-856.

PETERJ. TAORMINA and LARRY R. BEUCHAT-Center for Food Safety and QualityEnhancement, Department of Food Science and Technology, University of Georgia,1109 Experiment Street, Griffin, Georgia 30223-1797, USA

Abstract-Thebehavior of Escherichia coli O157:H7 on alfalfa seeds subjected toconditions similar to those used commercially to grow and market sprouts as itis affected by applications of NaOCl, Ca(OCl)₂, acidified NaClO₂,acidified ClO₂, Na₃PO₄, Vegi-Clean, Tsunami,Vortexx, or H₂O₂ at various stages of the sproutingprocess was determined. Application of 2,000 ppm of NaOCl, 200 and 2,000 ppm ofCa(OCl)₂, 500 ppm of acidified ClO₂, 10,000 ppm of Vegi-Clean,80 ppm of Tsunami, or 40 and 80 ppm of Vortexx to germinated seeds significantlyreduced the population of E. coli O157:H7. With the exception ofacidified NaOCl₂ at 1,200 ppm, spray applications of these chemicalsdid not significantly reduce populations or control the growth of E. coliO157:H7 on alfalfa sprouts during the sprouting process. Populations of E.coli on alfalfa sprouts peaked at 6 to 7 log₁₀ CFU/g 48 h afterinitiation of the sprouting process and remained stable despite further sprayingwith chemicals. The population of E. coli O157:H7 on sprouts as theyentered cold storage at 9 ± 2°C remained essentially unchanged for up to 6days. None of the chemical treatments evaluated was able to eliminate orsatisfactorily reduce E. coli O157:H7 on alfalfa seeds and sprouts.Observations on the ability of E. coli O157:H7 to grow during productionof alfalfa sprouts not subjected to chemical treatments are similar to thosefrom a previous study in our laboratory on the behavior of SalmonellaStanley. Our results do not reveal a chemical treatment method to eliminate thepathogen from alfalfa sprouts. We have demonstrated that currently recommendedprocedures for sanitizing alfalfa seeds fail to eliminate E. coliO157:H7and that the pathogen can grow to populations exceeding 7 log₁₀CFU/gof sprouts produced using techniques not dissimilar to those used in the sproutindustry.