Depuration of Oysters (Crassostrea gigas) Contaminated with Vibrio parahaemolyticus and Vibrio vulnificus with UV Light and Chlorinated Seawater

• Published in: Journal of food protection 2012-08, Vol.75 (8), p.1501-1506
• Main Authors: RAMOS, Roberta Juliano, MIOTTO, Marilia, LAGREZE SQUELLA, Francisco José, CIROLINI, Andréia, FERNANDO FERREIRA, Jaime, WERNECK VIEIRA, Cleide Rosana
• Format: Article
• Language: English
• Subjects: Animals; Bioaccumulation; Biological and medical sciences; Chlorine; Chlorine - pharmacology; Colony Count, Microbial; Consumer Product Safety; Crassostrea - microbiology; Crassostrea gigas; Decontamination; Fish and seafood industries; Food contamination & poisoning; Food Contamination - analysis; Food Contamination - prevention & control; Food Handling - methods; Food industries; Food microbiology; Food safety; Food science; Fundamental and applied biological sciences. Psychology; Gastroenteritis; Gram-negative bacteria; Humans; Laboratories; Light; Microorganisms; Mollusks; Oysters; Pasteurization; Pathogens; Retention; Salinity; Salt; Seafood; Seawater; Shellfish - microbiology; Shells; Ultraviolet radiation; Ultraviolet Rays; Vibrio parahaemolyticus; Vibrio parahaemolyticus - drug effects; Vibrio parahaemolyticus - isolation & purification; Vibrio parahaemolyticus - radiation effects; Vibrio vulnificus; Vibrio vulnificus - drug effects; Vibrio vulnificus - isolation & purification; Vibrio vulnificus - radiation effects
• ISSN: 0362-028X; 1944-9097
• DOI: 10.4315/0362-028X.JFP-11-467

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.