Oil‐in‐Water Emulsion as a Model System to Study the Growth of <i>Escherichia coli</i> O157:H7 in a Heterogeneous Food System

Prachaiyo, P.; McLandsborough, Lynne

doi:10.1111/j.1365-2621.2003.tb08281.x

Cited by 16 publications

(10 citation statements)

References 37 publications

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“…However, results contrary to ours are described in the literature. Prachaiyo and McLandsborough (2003) showed an increase in the generation time of bacteria as the hexadecane concentration increased. This is likely to be due to space limitation, nutrient limitation and/or the concentration of metabolic products.…”

Section: Discussionmentioning

confidence: 95%

Dispersed phase volume fraction, weak acids and Tween 80 in a model emulsion: Effect on the germination and growth of Bacillus weihenstephanensis KBAB4 spores

Léonard-Akkari

Guégan

Courand

et al. 2018

Food Research International

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In foodstuffs, physico-chemical interactions and/or physical constraints between spores, inhibitors and food components may exist. Thus, the objective of this study was to investigate such interactions using a model emulsion as a microbial medium in order to improve bacterial spore control with better knowledge of the interactions in the formulation. Emulsions were prepared with hexadecane mixed with nutrient broth using sonication and were stabilized by Tween 80 and Span 80. The hexadecane ratio was either 35% (v/v) or 50% (v/v) and each emulsion was studied in the presence of organic acid (acetic, lactic or hexanoic) at two pH levels (5.5 and 6). Self-diffusion coefficients of emulsion components and the organic acids were measured by Pulsed Field Gradient-Nuclear Magnetic Resonance (PFG-NMR). The inhibition effect on the spore germination and cell growth of Bacillus weihenstephanensis KBAB4 was characterized by the measure of the probability of growth using the most probable number methodology, and the measure of the time taken for the cells to germinate and grow using a single cell Bioscreen® method and using flow cytometry. The inhibition of spore germination and growth in the model emulsion depended on the dispersed phase volume fraction and the pH value. The effect of the dispersed phase volume fraction was due to a combination of (i) the lipophilicity of the biocide, hexanoic acid, that may have had an impact on the distribution of organic acid between hexadecane and the aqueous phases and (ii) the antimicrobial activity of the emulsifier Tween 80 detected at the acidic pH value. The interface phenomena seemed to have a major influence. Future work will focus on the exploration of these phenomena at the interface.

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Section: Discussionmentioning

confidence: 95%

Dispersed phase volume fraction, weak acids and Tween 80 in a model emulsion: Effect on the germination and growth of Bacillus weihenstephanensis KBAB4 spores

Léonard-Akkari

Guégan

Courand

et al. 2018

Food Research International

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“…Cell immobilization and growth in a structured medium may also cause alteration of cell morphology and physiological responses, affecting the thermal inactivation tolerance of the microorganisms (Mogollón, Marks, Booren, Orta-Ramirez & Ryser, 2009;Prachaiyo & McLandsborough, 2003), susceptibility to antibiotics (Jouenne, Tresse, & Junter, 1994;Junter, Coquet, Vilain, & Jouenne, 2002), protection from physicochemical stresses and cell membrane modification through the gene expression of some specific proteins Food Research International 64 (2014) 683-691 (Junter, Coquet, Vilain, & Jouenne, 2002). Cell immobilization and colonial growth also modify the local conditions in the growth environment; e.g., cell metabolism changes the substrate composition around the colony (Wimpenny et al, 1995) and acidic metabolites are accumulated, causing a drop of pH inside and around the colony (Malakar et al, 2002;Walker, Brocklehurst, & Wimpenny, 1997), and creating pH gradients in the growth medium (Walker, Brocklehurst, & Wimpenny, 1997;Wimpenny et al, 1995).…”

Section: Introductionmentioning

confidence: 99%

Effect of the substrate's microstructure on the growth of Listeria monocytogenes

Aspridou

Moschakis

Βiliaderis

et al. 2014

Food Research International

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“…In most of these cases, gelatin was used to induce a gelled microstructure. Other experimental setups used agar or gelatin gels in petri dishes (1,2,3,48) or studied bacterial growth in oil-in-water emulsions (9,38,39).…”

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confidence: 99%

Design of an Experimental Viscoelastic Food Model System for Studying Zygosaccharomyces bailii Spoilage in Acidic Sauces

Mertens

Dang

Vermeulen

et al. 2009

Appl Environ Microbiol

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Within the field of predictive microbiology, the number of studies that quantify the effect of food structure on microbial behavior is very limited. This is mainly due to impracticalities related to the use of a nonliquid growth medium. In this study, an experimental food model system for studying yeast spoilage in acid sauces was developed by selecting a suitable thickening/gelling agent. In a first step, a variety of thickening/gelling agents was screened, with respect to the main physicochemical (pH, water activity, and acetic acid and sugar concentrations) and rheological (weak gel viscoelastic behavior and presence of a yield stress) characteristics of acid sauces. Second, the rheological behavior of the selected thickening/gelling agent, Carbopol 980, was extensively studied within the following range of conditions: pH 4.0 to 5.0, acetic acid concentration of 0 to 1.0% (vol/vol), glycerol concentration of 0 to 15% (wt/vol), and Carbopol concentration of 1.0 to 1.5% (wt/vol). Finally, the applicability of the model system was illustrated by performing growth experiments in microtiter plates for Zygosaccharomyces bailii at 0, 0.5, 1.0, and 1.5% (wt/vol) Carbopol, 5% (wt/vol) glycerol, 0% (vol/vol) acetic acid, and pH 5.0. A shift from planktonic growth to growth in colonies was observed when the Carbopol concentration increased from 0.5 to 1.0%. The applicability of the model system was illustrated by estimating max at 0.5% Carbopol from absorbance detection times.Food structure is, next to the chemical composition and storage conditions, one of the key factors that affect microbial behavior in food products. The effects of food structure are mainly related to the mechanical distribution of water, the chemical redistribution of organic acids, and the mobility of microorganisms (55). In the case of a liquid food product, microbial growth is typically planktonic, and transport of nutrients and metabolites occurs by diffusion, resulting in a homogeneous environment. The majority of foods, however, have some degree of structure, causing microorganisms to be immobilized and constrained to grow as colonies. Within the field of predictive microbiology, where mathematical models are developed for describing microbial growth, inactivation, and survival in food (model systems), most models are based on data obtained in liquid broth media. The scarcity of predictive models that incorporate the effect of structure has been recognized as one of the most important shortcomings in this field of research (41).Conducting experiments on a structured culture medium gives rise to several impracticalities due to the nonliquid nature of the culture medium. Starting from a liquid culture medium, a thickening or gelling agent is added to obtain a structured model system that, ideally, mimics the microstructural properties of the target food product. In order to evaluate the effect of structure on a systematic and consistent basis, the experi-

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Oil‐in‐Water Emulsion as a Model System to Study the Growth of Escherichia coli O157:H7 in a Heterogeneous Food System

Cited by 16 publications

References 37 publications

Dispersed phase volume fraction, weak acids and Tween 80 in a model emulsion: Effect on the germination and growth of Bacillus weihenstephanensis KBAB4 spores

Dispersed phase volume fraction, weak acids and Tween 80 in a model emulsion: Effect on the germination and growth of Bacillus weihenstephanensis KBAB4 spores

Effect of the substrate's microstructure on the growth of Listeria monocytogenes

Design of an Experimental Viscoelastic Food Model System for Studying Zygosaccharomyces bailii Spoilage in Acidic Sauces

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