Comparative Growth ofEscherichia coli 0157:H7, Spoilage Organisms and Shelf-Life of Shredded Iceberg Lettuce Stored under Modified Atmospheres
✍ Scribed by Diaz, C; Hotchkiss, J H
- Book ID
- 102648694
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 568 KB
- Volume
- 70
- Category
- Article
- ISSN
- 0022-5142
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✦ Synopsis
The objective of this work was to compare organoleptic and microbiological spoilage with the survival of Escherichia coli 0157: H7 in modified atmosphere (MA) stored shredded lettuce. The rates of growth of E coli 0157:H7, increase in aerobic plate counts (APC g-'), and rates of visual spoilage of shredded lettuce held under air or MA at 13 and 22°C were compared. Samples were inoculated with nalidixic acid-resistant E coli 0157:H7 (ATCC 35150) and placed in a chamber which was continuously flushed with gas mixtures of 0/10/90, 3/0/97, 5/30/65, 20/0/80 (O,/CO,/N, , v/v) and held at 13 or 22°C. APC growth was inhibited in 5/30/65 (O,/CO,/N,) at 13°C compared to all other atmospheres which were not significantly different from each other. The growth rates for both E coli 0157:H7 and APC were greatest in air at 22°C. Carbon dioxide concentration had no significant effect on the growth of E coli 0157:H7 at either temperature. The shelf-life of shredded lettuce, as judged by appearance, was extended in atmospheres containing 30% CO, by approximately 300% compared to air. The APC were similar at the time when the shredded lettuce samples were judged unacceptable regardless of shelf-life. However, the extended shelf-life provided by the MA allowed E coli 0157:H7 to grow to higher numbers compared to air-held shredded lettuce.