Inactivation ofVibrio parahaemolyticusin shucked raw oyster (Grassostrea gigas) and clam (Venerupis phillippinarum) by using a combination of NaClO and gamma irradiation

Abstract

This study investigated the synergistic effects of sodium hypochlorite (NaClO) and gamma irradiation combination against Vibrio parahaemolyticus in shucked oysters and clams. V. parahaemolyticus decreased to 1.1-5.6 log CFU/g in oysters and 1.1-5.7 logCFU/g in clams by NaClO (20-80 ppm) + γ irradiation (0.1-2.0 kGy) combinations. V. parahaemolyticus was not detected by 60 or 80 ppm NaClO + 2.0 kGy. Synergistic reduction of >1 log was observed by 60 ppm NaClO + 0.3-2 kGy and 80 ppm NaClO + 0.5 or 2 kGy. Specifically, >2 log of the synergistic reduction was obtained by 60 or 80 ppm NaClO + 2 kGy. Furthermore, using the Weibull model, 5D values (5-log reductions) were calculated for 60 or 80 ppm NaClO + 0.5-0.9 kGy. No significant differences were observed for all sensory parameters between samples of 2.0 kGy + 0-80 ppm NaClO. This study suggests that 60 ppm NaClO + 2.0 kGy in reducing 7-log V. parahaemolyticus without any deteriorative changes of sensory qualities could be a potential strategy for post-harvest process in seafood processing and distribution to enhance the microbial safety of molluscan shellfish.

Managing the risk of Vibrio parahaemolyticus infections associated with oyster consumption: A review

“…Shen and Su (2017) report that depuration of oyster samples at 12.5 °C for 4 and 5 days reduced the concentration of V. parahaemolyticus in samples by 3.1 and 3.7 orders of magnitude, respectively; they further reported that the concentration decreased by 3.0 and 4.2 orders of magnitude after 2 days of depuration at 12.5 °C in ASW with the addition of 1.0% and 1.5% grape seed extract (GSE), respectively (Shen & Su, 2017). Park and Ha (2018) evaluated a combination of sodium hypochlorite (NaClO) and gamma irradiation against V . p arahaemolyticus in shucked oysters and found that 2 kGy of gamma irradiation combined with 60 ppm of NaClO reduced the concentration of V. parahaemolyticus by 3.6 orders of magnitude.…”

“…p arahaemolyticus in shucked oysters and found that 2 kGy of gamma irradiation combined with 60 ppm of NaClO reduced the concentration of V. parahaemolyticus by 3.6 orders of magnitude. Increasing the concentration of NaClO to 80 ppm combined with 2 kGy of gamma irradiation reduced the concentration of V. parahaemolyticus in shucked oysters by 2.2 orders of magnitude (Park & Ha, 2018). Shen et al.…”