title: Depuration of Oysters (Crassostrea gigas) contaminated with Vibrio parahaemolyticus and Vibrio vulnificus with UV light and chlorinated seawater.
abstract: The efficacy of depuration using UV light and chlorinated seawater for decontaminating Vibrio parahaemolyticus and Vibrio vulnificus from oysters was investigated. Oysters were contaminated with a five-strain cocktail of V. parahaemolyticus or V. vulnificus  to levels of 10(4) to 10(5) CFU ml(-1) for bioaccumulation. The depuration was conducted in a closed system in which 350 liters of seawater was recirculated at a rate of 7 liters/min for 48 h at room temperature. Counts of V. parahaemolyticus or V.  vulnificus were determined at 0, 6, 18, 24, and 48 h. Three treatments were conducted: T1, control treatment; T2, UV treatment; and T3, UV plus chlorine treatment. After 48 h of depuration of V. parahaemolyticus, T3 reduced the count by 3.1 log most probable number (MPN) g(-1)  and T2 reduced the count by 2.4 log MPN g(-1), while T1 reduced the count by only 2.0 log MPN g(-1). After 48 h of depuration of V. vulnificus, T2 and T3 were efficient, reducing the counts by 2.5 and 2.4 log MPN g(-1), respectively, while  T1 reduced the count by only 1.4 log MPN g(-1). The UV light plus chlorine treatment was more efficient for controlling V. parahaemolyticus in oysters. Both UV light and UV light plus chlorine were efficient for V. vulnificus. The present study is the first report  showing the efficacy of depuration systems for decontaminating V. parahaemolyticus and V. vulnificus in oysters cultivated on the Brazilian coast. This study provides information on processes that can contribute to controlling and preventing such microorganisms in oysters and  could be used for effective postharvest treatment by restaurants and small producers of oysters on the coast of Brazil.
authors.affiliation: Laboratory of Food Microbiology, Department of Food Science & Technology, Federal University of Santa Catarina, Florianopolis, Santa Catarina, Brazil. robertajulianoramos@yahoo.com.br
authors.forename: Roberta Juliano
authors.initials: RJ
authors.lastname: Ramos
authors.forename: Marília
authors.initials: M
authors.lastname: Miotto
authors.forename: Francisco José Lagreze
authors.initials: FJ
authors.lastname: Squella
authors.forename: Andréia
authors.initials: A
authors.lastname: Cirolini
authors.forename: Jaime Fernando
authors.initials: JF
authors.lastname: Ferreira
authors.forename: Cleide Rosana Werneck
authors.initials: CR
authors.lastname: Vieira
mesh_terms: D000818:Animals; D002713:Chlorine / Q000494:pharmacology*; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D049896:Crassostrea / Q000382:microbiology*; D005506:Food Contamination / Q000032:analysis / Q000517:prevention & control; D005511:Food Handling / Q000379:methods*; D006801:Humans; D012623:Seawater; D012758:Shellfish / Q000382:microbiology*; D014466:Ultraviolet Rays; D014736:Vibrio parahaemolyticus / Q000187:drug effects / Q000302:isolation & purification* / Q000528:radiation effects; D041261:Vibrio vulnificus / Q000187:drug effects / Q000302:isolation & purification* / Q000528:radiation effects
chemical_list: D002713:Chlorine