Influence of vacuum cooling on Escherichia coli O157: H7 infiltration in fresh leafy greens via a multiphoton-imaging approach

Erica Vonasek, Nitin Nitin

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Microbial pathogen infiltration in fresh leafy greens is a significant food safety risk factor. In various postharvest operations, vacuum cooling is a critical process for maintaining the quality of fresh produce. The overall goal of this study was to evaluate the risk of vacuum cooling-induced infiltration of Escherichia coli O157:H7 into lettuce using multiphoton microscopy. Multiphoton imaging was chosen as the method to locate E. coli O157:H7 within an intact lettuce leaf due to its high spatial resolution, low background fluorescence, and near-infrared (NIR) excitation source compared to those of conventional confocal microscopy. The variables vacuum cooling, surface moisture, and leaf side were evaluated in a three-way factorial study with E. coli O157:H7 on lettuce. A total of 188 image stacks were collected. The images were analyzed for E. coli O157:H7 association with stomata and E. coli O157:H7 infiltration. The quantitative imaging data were statistically analyzed using analysis of variance (ANOVA). The results indicate that the low-moisture condition led to an increased risk of microbial association with stomata (P < 0.05). Additionally, the interaction between vacuum cooling levels and moisture levels led to an increased risk of infiltration (P < 0.05). This study also demonstrates the potential of multiphoton imaging for improving sensitivity and resolution of imaging-based measurements of microbial interactions with intact leaf structures, including infiltration.

Original languageEnglish (US)
Pages (from-to)106-115
Number of pages10
JournalApplied and Environmental Microbiology
Volume82
Issue number1
DOIs
StatePublished - 2016

Fingerprint

Escherichia coli O157
green leafy vegetables
Vacuum
infiltration
cooling
Lettuce
image analysis
stomata
moisture
lettuce
microscopy
Microbial Interactions
leaf lettuce
fresh produce
food safety
Food Safety
risk factor
Confocal Microscopy
variance analysis
leaves

ASJC Scopus subject areas

  • Applied Microbiology and Biotechnology
  • Food Science
  • Biotechnology
  • Ecology

Cite this

Influence of vacuum cooling on Escherichia coli O157 : H7 infiltration in fresh leafy greens via a multiphoton-imaging approach. / Vonasek, Erica; Nitin, Nitin.

In: Applied and Environmental Microbiology, Vol. 82, No. 1, 2016, p. 106-115.

Research output: Contribution to journalArticle

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