Ultrasound decontamination of minimally processed fruits and vegetables

Seymour, Ian; Burfoot, D.; Smith, R. L.; Cox, Linda A.; Lockwood, Alex

doi:10.1046/j.1365-2621.2002.00613.x

Cited by 207 publications

(105 citation statements)

References 27 publications

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“…Each pathogen was inoculated onto the cut lettuce, which was purchased from a local supermarket and cut into pieces ca. 1 by 1 cm on the day of experiment to obtain an inoculum level of 10 2 to 10 3 CFU/g using the sprinkle method (22,41,42,53). Leaf samples of 100 g were placed into separate plastic bags (25 by 20 cm) to facilitate bacterial inoculation.…”

Section: Methodsmentioning

confidence: 99%

Modeling of Pathogen Survival during Simulated Gastric Digestion

Koseki

Mizuno

Sotome

2011

Appl Environ Microbiol

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The objective of the present study was to develop a mathematical model of pathogenic bacterial inactivation kinetics in a gastric environment in order to further understand a part of the infectious dose-response mechanism. The major bacterial pathogens Listeria monocytogenes, Escherichia coli O157: H7, and Salmonella spp. were examined by using simulated gastric fluid adjusted to various pH values. To correspond to the various pHs in a stomach during digestion, a modified logistic differential equation model and the Weibull differential equation model were examined. The specific inactivation rate for each pathogen was successfully described by a square-root model as a function of pH. The square-root models were combined with the modified logistic differential equation to obtain a complete inactivation curve. Both the modified logistic and Weibull models provided a highly accurate fitting of the static pH conditions for every pathogen. However, while the residuals plots of the modified logistic model indicated no systematic bias and/or regional prediction problems, the residuals plots of the Weibull model showed a systematic bias. The modified logistic model appropriately predicted the pathogen behavior in the simulated gastric digestion process with actual food, including cut lettuce, minced tuna, hamburger, and scrambled egg. Although the developed model enabled us to predict pathogen inactivation during gastric digestion, its results also suggested that the ingested bacteria in the stomach would barely be inactivated in the real digestion process. The results of this study will provide important information on a part of the dose-response mechanism of bacterial pathogens.Dose-response models play an important role in characterizing the risk in quantitative microbial risk assessments (15). The currently available dose-response models of microbial risk assessment are derived from the following different source data: human-feeding volunteer tests (14), extrapolation of the results of animal experiments to humans (44, 51), and estimations from epidemiological studies of outbreaks of food-borne illness (8). However, these approaches to dose-response modeling of low-dose exposures to pathogens rely on multiple assumptions and extrapolations, which reflect the current lack of knowledge regarding the fundamental mechanisms underlying the responses to a dose (10).Recently, a new concept, called the key-events dose-response framework (KEDRF), has been introduced as an alternative approach for the development of dose-response models (10). In the KEDRF approach, the following five major and necessary steps, termed key events, are proposed: (i) survival of pathogens in the upper gastrointestinal tract, (ii) establishment in the intestine and attachment to and uptake into epithelial cells, (iii) survival and escape from phagosomes in enterocytes and transfer of pathogen to phagocytes, (iv) transfer of pathogens across placenta, and (v) pathogen growth leading to fetal morbidity and mortality.At each step, the ranges of facto...

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Section: Methodsmentioning

confidence: 99%

Modeling of Pathogen Survival during Simulated Gastric Digestion

Koseki

Mizuno

Sotome

2011

Appl Environ Microbiol

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“…Ultrasound can be combined with other decontamination technologies for enhancing microbial inactivation (Sango, Abela, McElhatton, & Valdramidis, 2014). The effect of cavitation generated by the ultrasound appeared to enhance the removal of attached or entrapped cells on the surfaces of fresh produce, rendering the bacteria more susceptible to antimicrobial sanitizers (Seymour, Burfoot, Smith, Cox, & Lockwood, 2002). Essential oils such as oregano or thyme are natural sanitizers and they are considered as Generally Recognized as Safe (GRAS) food ingredients and can be used as postharvest treatment for controlling bacteria growth.…”

Section: Introductionmentioning

confidence: 99%

Determination of the efficacy of ultrasound combined with essential oils on the decontamination of Salmonella inoculated lettuce leaves

Millan-Sango

Garroni

Farrugia

et al. 2016

LWT

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a b s t r a c tSalmonella is one of main pathogenic bacteria present in fresh produce. Ultrasound has been reported to be effective at inactivating food-borne pathogens. Moreover, ultrasound can be combined with essential oils to enhance its efficacy. This study evaluates the reduction and inactivation of Salmonella enterica Abony inoculated on lettuce leaves by the application of continuous and pulsed ultrasound as well as ultrasound combined with the essential oil of oregano and thyme. The physicochemical properties of these essential oil nanoemulsions are characterised while the structural damage of treated leaves is determined by the electrolyte leakage. Ultrasound combined with essential oils enhanced the microbial reduction on lettuce leaves and inactivation on the treated water, resulting on significant differences at concentrations higher than 0.018% (v/v) compared to control. Particle size, zeta potential and pH varied between 35 and 133 nm, À26 to À36 mV and 5.67 to 5.38, respectively. Electrolyte leakage was similar for both the control and the treated samples, increasing when essential oils were applied.

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“…The total volume of liquid was approximately 5 dm 3 and it was not temperature controlled. It is essential that the nozzle structure is full of liquid while it is in operation and so the nozzle was orientated so that the bleed outlet was upper-most, allowing air to be expelled through this outlet.…”

Section: Methodsmentioning

confidence: 99%