Antimicrobial Effects of Vinegar Against Norovirus and Escherichia Coli in the Traditional Korean Vinegared Green Laver (Enteromorpha Intestinalis) Salad During Refrigerated Storage

Int J Food Microbiol. 2016 Dec 5;238:208-214. doi: 10.1016/j.ijfoodmicro.2016.09.002. Epub 2016 Sep 5.

Abstract

In Korea, edible seaweeds are potentially regarded as high-risk foods with respect to enteric norovirus (NoV) and non-pathogenic generic Escherichia coli. This study investigated the antimicrobial effects of 5%, 10%, and 15% vinegar (6% acetic acid) on the survival of murine norovirus-1 (MNV-1), a human NoV surrogate, and E. coli, a fecal indicator in experimentally contaminated raw fresh green lavers (Enteromorpha intestinalis) during a 7-d storage period at 4°C. Both MNV-1 titers and E. coli counts significantly (p<0.05) decreased with stepwise increase in vinegar concentration and storage time, except in E. coli of the 0% vinegar-containing lavers; however, MNV-1 was more resistant to vinegar than E. coli. The overall average MNV-1 titers were significantly (p<0.05) higher in 0% vinegar-containing lavers (3.6log10PFU/ml) than in 5-15% vinegar-containing lavers (3.3-3.1log10PFU/ml) throughout the 7days of storage. A 1-log reduction in the MNV-1 titer was observed in 0% vinegar-containing laver samples after 5days of storage and 5-15% vinegar-containing laver samples after 3days of storage. The overall E. coli count was also significantly (p<0.05) decreased in the 15% (6.8log10CFU/g) vinegar-containing lavers than in the 10% (7.3log10CFU/g) and 5% (7.6log10CFU/g) vinegar-containing lavers. A >1-log reduction in the E. coli count was observed in 10-15% vinegar-containing laver samples just after 1day of storage. A 2-log reduction in the E. coli count was also observed in 10-15% vinegar-containing laver samples after 5days of storage. Using the non-linear Weibull model, this study showed that the dR-values (1-log reduction) of MNV-1 were 4.90days for 0%, 4.28days for 5%, 3.79days for 10%, and 2.88days for 15% vinegar-containing lavers, whereas those for E. coli were 1.12day for 5%, 1.03day for 10%, and 0.90day for 15% vinegar-containing lavers stored at 4°C. Vinegar with over the storage time can be used as an antimicrobial ingredient against NoV and E. coli in Korean conventional foods. Specifically, this study suggests that ~1day of storage is required for 1-log reduction in the E. coli count in the vinegar-containing (5-15%) lavers, whereas 3-5days of storage at 4°C is adequate for 1-log reduction in the MNV-1 count in the vinegar-containing and non-vinegar-containing lavers.

Keywords: E. coli; Fresh green laver; Murine norovirus-1; Storage; Vinegar.

Publication types

  • Evaluation Study

MeSH terms

  • Acetic Acid / pharmacology*
  • Anti-Infective Agents / pharmacology
  • Escherichia coli / drug effects*
  • Escherichia coli / growth & development
  • Food Preservation / instrumentation
  • Food Preservation / methods*
  • Food Storage
  • Humans
  • Norovirus / drug effects*
  • Norovirus / growth & development
  • Republic of Korea
  • Ulva / microbiology*
  • Vegetables / microbiology*

Substances

  • Anti-Infective Agents
  • Acetic Acid