Articles
Viability of chlorine-injured indicator and pathogenic coliform bacteria on fresh-cut cabbage stored in high CO2 atmospheres
Article number
1275_2
Pages
7 – 14
Language
English
Abstract
Electrolyzed water containing chlorine can induce bacteria to be in a sublethal, injured state.
Sublethally injured indicator and pathogenic coliform bacteria on shredded cabbage were evaluated during storage in air or high CO2 controlled atmospheres (CA) of 5, 10, and 15% at 10°C and in a modified atmosphere packaging (MAP) using two types of packaging (an equilibrium of 5% CO2/15% O2 and 15% CO2/ 5% O2) at 5 and 10°C, using the thin agar layer (TAL) method.
When shredded cabbage rinsed with electrolyzed water containing 25 ppm available chlorine was stored in a CA and MAP, coliform counts on TAL plates increased 2-3.2 log and 3-4.5 log from the initial counts during storage at 5 and 10°C, respectively, with the increase being greater in low CO2 atmospheres.
The extent of injury ranging from 24 to 87% for the coliform bacteria was detected on samples on the initial day and during subsequent storage irrespective of the CO2 atmosphere, except for a MAP storage at 10°C. Shredded cabbage was inoculated with chlorine-injured E. coli O157:H7 (% injury = 45-65%) by using electrolyzed water containing 1 ppm available chlorine, and then stored in a CA and MAP. Counts of E. coli O157:H7 on TAL plates increased 0.5-1.4 log from the initial counts during storage at 10°C, with the increase being greater in high CO2 atmospheres.
Chlorine-injured E. coli O157:H7 (% injury = 34-74%) were detected on samples during storage irrespective of the CO2 atmosphere and temperature.
These results indicated that chlorine-injured indicator and pathogenic bacteria on fresh-cut cabbage were capable of exhibiting different degrees of injury during storage regardless of the storage atmosphere and temperature.
Sublethally injured indicator and pathogenic coliform bacteria on shredded cabbage were evaluated during storage in air or high CO2 controlled atmospheres (CA) of 5, 10, and 15% at 10°C and in a modified atmosphere packaging (MAP) using two types of packaging (an equilibrium of 5% CO2/15% O2 and 15% CO2/ 5% O2) at 5 and 10°C, using the thin agar layer (TAL) method.
When shredded cabbage rinsed with electrolyzed water containing 25 ppm available chlorine was stored in a CA and MAP, coliform counts on TAL plates increased 2-3.2 log and 3-4.5 log from the initial counts during storage at 5 and 10°C, respectively, with the increase being greater in low CO2 atmospheres.
The extent of injury ranging from 24 to 87% for the coliform bacteria was detected on samples on the initial day and during subsequent storage irrespective of the CO2 atmosphere, except for a MAP storage at 10°C. Shredded cabbage was inoculated with chlorine-injured E. coli O157:H7 (% injury = 45-65%) by using electrolyzed water containing 1 ppm available chlorine, and then stored in a CA and MAP. Counts of E. coli O157:H7 on TAL plates increased 0.5-1.4 log from the initial counts during storage at 10°C, with the increase being greater in high CO2 atmospheres.
Chlorine-injured E. coli O157:H7 (% injury = 34-74%) were detected on samples during storage irrespective of the CO2 atmosphere and temperature.
These results indicated that chlorine-injured indicator and pathogenic bacteria on fresh-cut cabbage were capable of exhibiting different degrees of injury during storage regardless of the storage atmosphere and temperature.
Authors
H. Izumi, A. Inoue
Keywords
injured bacteria, coliforms, Escherichia coli O157:H7, controlled atmosphere, modified atmosphere packaging
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