Inactivation Kinetics of Vibrio Vulnificus in Phosphate-Buffered Saline at Different Freezing and Storage Temperatures and Times

Authors

  • Diana M. Seminario,

    1. Author Balaban is with Fishery Industrial Technology Center, Univ. of Alaska Fairbanks, School of Fisheries & Ocean Sciences, Kodiak, AK, U.S.A. Authors Seminario and Rodrick are with Food Science and Human Nutrition Dept., Univ. of Florida, Gainesville, FL, U.S.A. Direct inquiries to author Balaban (E-mail: MuratKodiak@gmail.com).
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  • Murat O. Balaban,

    1. Author Balaban is with Fishery Industrial Technology Center, Univ. of Alaska Fairbanks, School of Fisheries & Ocean Sciences, Kodiak, AK, U.S.A. Authors Seminario and Rodrick are with Food Science and Human Nutrition Dept., Univ. of Florida, Gainesville, FL, U.S.A. Direct inquiries to author Balaban (E-mail: MuratKodiak@gmail.com).
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  • Gary Rodrick

    1. Author Balaban is with Fishery Industrial Technology Center, Univ. of Alaska Fairbanks, School of Fisheries & Ocean Sciences, Kodiak, AK, U.S.A. Authors Seminario and Rodrick are with Food Science and Human Nutrition Dept., Univ. of Florida, Gainesville, FL, U.S.A. Direct inquiries to author Balaban (E-mail: MuratKodiak@gmail.com).
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Abstract

Abstract: Vibrio vulnificus (Vv) is a pathogen that can be found in raw oysters. Freezing can reduce Vv and increase the shelf life of oysters. The objective of this study was to develop predictive inactivation kinetic models for pure cultures of Vv at different frozen storage temperatures and times. Vv was diluted in phosphate-buffered saline (PBS) to obtain about 107 CFU/mL. Samples were frozen at −10, −35, and −80 °C (different freezing rates), and stored at different temperatures. Survival of Vv was followed after freezing and storage at −10 °C (0, 3, 6, and 9 d) and at −35 and −80 °C (every week for 6 wk). For every treatment, time–temperature data was obtained using thermocouples in blank vials. Predictive models were developed using first-order, Weibull and Peleg inactivation kinetics. Different freezing temperatures did not significantly (α= 0.05) affect survival of Vv immediately after freezing. The combined effect of freezing and 1 wk frozen storage resulted in 1.5, 2.6, and 4.9 log10 reductions for samples stored at −80, −35, and −10 °C, respectively. Storage temperature was the critical parameter in survival of Vv. A modified Weibull model successfully predicted Vv survival during frozen storage: inline image. No and Nt are initial and time t (d) survival counts, T is frozen storage temperature, Celsius degree.

Practical Application: Vibrio vulnificus can be inactivated by freezing. Models to predict survival of V. vulnificus at different freezing temperatures and times were developed. This is the first step towards the prediction of V. vulnificus related safety of frozen oysters.

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