On the use of the Weibull model to describe thermal inactivation of microbial vegetative cells

This research investigated the efficacy of gaseous ozone for the inactivation of Escherichia coli ATCC 25922 and NCTC 12900 strains in orange juice. Orange juice inoculated with E. coli (10 6 CFU mL -1 ) as a challenge microorganism was treated with ozone at 75-78µg mL -1 for different time periods (0-18 min). The efficacy of ozone for inactivation of both strains of E. coli was evaluated as a function of different juice types: model orange juice, fresh unfiltered juice, juice without pulp, and juice filtered through 500m or 1mm sieves. Fast inactivation rates for total reduction of E. coli were achieved in model orange juice (60 seconds) and in juice with low pulp content (6 min). However, in unfiltered juice inactivation was achieved after 15-18 min. This indicated that juice organic matter interferes with antibacterial activity of gaseous ozone. The effect of prior acid (pH 5.0) exposure of E. coli strains on the inactivation efficacy of ozone treatment was also investigated. There was a strain effect observed, where prior acid exposure resulted in higher inactivation times in some cases by comparison with the control cells.However, the overarching influence on inactivation efficacy of ozone was related to the pulp content. Generally, the applied gaseous ozone treatment of orange juice resulted in a population reduction of 5 log cycles.Key words: Escherichia coli, ozone, non-thermal inactivation, acid exposure, orange juice, microbial kinetics Industrial relevance: To facilitate the preservation of unstable nutrients many juice processors have investigated alternatives to thermal pasteurisation, including unpasteurised short shelf life juices with high retail value. This trend has continued within the European Union. However within the US recent regulations by the FDA have 3 required processors to achieve a 5-log reduction in the numbers of the most resistant pathogens in their finished products. Pathogenic E. coli may survive in acid environments such as fruit juices for long periods. This study demonstrates that the use of ozone as a non-thermal technology is effective for inactivation of E. coli and acid exposed E. coli in orange juice. Information on the design of the ozone treatment for inactivation of E. coli which results into safe juice products is also among the main outputs of this work. Ozone auto-decomposition makes this technology safe for fruit juice processing.4

show abstract

“…The Weibull distribution corresponds to a concave upward survival curve if p<1 and concave downward if p >1 (Van Boekel, 2002).…”

Section: Inactivation Kineticsmentioning

confidence: 99%

Inactivation of Escherichia coli in orange juice using ozone

Patil¹,

Bourke²,

Frias³

et al. 2009

Innovative Food Science & Emerging Technologies

112

View full text Add to dashboard Cite

show abstract

“…The cumulative form of Weibull frequency distribution model was used to describe Campylobacter survival kinetics in water as it is suitable for quantifying Page 5 / 19 bacterial survival for both log and non-log linear survival curves. The Weibull model has largely been used to describe bacterial inactivation by thermal and nonthermal processes as stress resistance of a microbial population often follows a Weibull distribution (Cunhan et al, 1998;Peleg and Cole, 1998;Fernandez et al, 1999;van Boekel, 2002;Corradini and Peleg, 2003;Virto et al, 2005;Hajmeer et al, 2006). We used a logarithm decimal form of Weibull defined as follows (Mafart et al, 2002;van Boekel, 2002):…”

Section: Campylobacter Infectionsmentioning

confidence: 99%

Survival of Campylobacter jejuni in mineral bottled water according to difference in mineral content: Application of the Weibull model

Guillou

Leguérinel²,

Garrec³

et al. 2008

Water Research

View full text Add to dashboard Cite

The aim of the study was to examine the hypothesis emitted by Evans et al. (2003) that mineral bottled water accidentally contaminated by Campylobacter jejuni would represent a risk factor for Campylobacter infection.Culturability of C. jejuni cells inoculated in low and high mineral bottled water during storage at 4°C in the dark was performed by surface plating and modelled using the Weibull model.The loss of C. jejuni culturability observed in all conditions tested was shown to be dependent from strain, preculture condition and water composition.Following inoculation of C. jejuni, the rapid loss of culturability was not correlated to complete cell death as the passage into embryonated eggs enabled recovery of cells from the Viable But Non Culturable state.In conclusion, the sanitary risk associated to contaminated bottled water can not be excluded although it is presumably low. Culture conditions, strain and water type must be taken into account in the evaluation of the risk factor as they influence significantly Campylobacter survival in water.

show abstract

“…Models developed over the last three decades for microbial inactivation included the concepts of population dynamics of the spores and are empirical in nature (Rodriguez et al ., 1992; van Boekel, 2002; Corradini and Peleg, 2003; Peleg, 2003; Corradini et al ., 2007). Table 1 shows a list of persistence models for microbial inactivation along with their equations and references that give the basis of inactivation along with experimental factors such as concentration, temperature, relative humidity or time.…”

Section: Introductionmentioning

confidence: 99%

Evaluating the long‐term persistence of Bacillus spores on common surfaces

Enger

Mitchell

Murali

et al. 2018

Microbial Biotechnology

View full text Add to dashboard Cite

Summary Bacillus spores resist inactivation, but the extent of their persistence on common surfaces is unclear. This work addresses knowledge gaps regarding biothreat agents in the environment to reduce uncertainty in risk assessment models. Studies were conducted to investigate the long‐term inactivation of Bacillus anthracis and three commonly used surrogate organisms – B. cereus, B. atrophaeus and B. thuringiensis on three materials: laminate countertop, stainless steel and polystyrene Petri dishes. Viable spores were measured at 1, 30, 90, 196, 304 and 1038 days. Twelve different persistence models were fit to the data using maximum likelihood estimation and compared. The study found that (1) spore inactivation was not log‐linear, as commonly modelled; (2) B. thuringiensis counts increased at 24 h on all materials, followed by a subsequent decline; (3) several experiments showed evidence of a ‘U’ shape, with spore counts apparently decreasing and then increasing between 1 and 304 days; (4) spores on polystyrene showed little inactivation; and (5) the maximum inactivation of 56% was observed for B. atrophaeus spores on steel at 196 days. Over the range of surfaces, time durations and conditions (humidity controlled vs. uncontrolled) examined, B. thuringiensis most closely matched the behaviour of B. anthracis.

show abstract

On the use of the Weibull model to describe thermal inactivation of microbial vegetative cells

Cited by 840 publications

References 68 publications

Inactivation of Escherichia coli in orange juice using ozone

Inactivation of Escherichia coli in orange juice using ozone

Survival of Campylobacter jejuni in mineral bottled water according to difference in mineral content: Application of the Weibull model

Evaluating the long‐term persistence of Bacillus spores on common surfaces

Contact Info

Product

Resources

About