0000000000162167
AUTHOR
Philippe Dantigny
showing 31 related works from this author
Mould germination: data treatment and modelling.
2006
Abstract The objectives of this study were i/ to examine germination data sets over a range of environmental conditions (water activity, temperature) for eight food spoilage moulds, ii/ to compare the ability of the Gompertz equation and logistic function to fit the experimental plots, iii/ to simulate germination by assessing various distributions of the latent period for germination amongst a population of spores. Data sets (percentage germination, P (%), versus time, t) of Aspergillus carbonarius, Aspergillus ochraceus, Fusarium verticillioides, Fusarium proliferatum, Gibberella zeae, Mucor racemosus, Penicillium chrysogenum and Penicillium verrucosum were analysed. No correlation, or re…
Distributions of the growth rate of the germ tubes and germination time of Penicillium chrysogenum conidia depend on water activity
2008
The effects of water activities for sporulation (a(wsp)) and germination (a(wge)) on the distributions of the growth rate of the germ tubes (mu) and the germination time (t(G)) of Penicillium chrysogenum conidia were determined by monitoring the length of the same germ tubes throughout the experiments automatically. No relationship between the individual t(G)'s and mu's could be established. Irrespective of the water activity for germination, mu was greater and t(G) was less for conidia produced at 0.95a(wsp) than that at 0.99a(wsp). At 0.99 a(wge) the mean and the standard deviation of t(G) were smaller than those obtained at 0.95a(wge). At 0.99a(wge), normal distributions for mu and t(G) …
Use of a logistic model to assess spoilage by Byssochlamys fulva in clarified apple juice
2010
Abstract The percentage P (%) of spoiled bottles (n = 40) of clarified apple juice due to Byssochlamys fulva, was modeled by using a logistic model: P = P max 1 + exp ( k ( τ − t ) ) where Pmax (%) the maximum percentage of spoiled bottles, k (h− 1) a slope parameter and τ (h) the time for P = Pmax/2. Bottles of pasteurized apple juice were inoculated with B. fulva IOC 4518 ascospores for low and high initial loads, 4.8 ± 2.3 ascospores/100 mL and 19.3 ± 4.6 ascospores/100 mL respectively and incubated at 21 °C and 30 °C. Pmax was not significantly different from 100% except for a low initial load at 21 °C. Model parameters were estimated with a good accuracy, RMSE in the range 3.89–7.50. T…
A temperature-type model for describing the relationship between fungal growth and water activity
2001
Growth of Penicillium chrysogenum, Aspergillus flavus, Cladosporium cladosporioides and Alternaria alternata at their respective optimum temperatures was studied in Potato Dextrose Agar (PDA) medium at different water activities (a(w)) adjusted with glycerol. The growth rate (mu) was expressed as the increase in colony radius per unit of time. This paper extends the model that showed the relationship between temperature and bacterial growth rate developed by Rosso et al. [J. Theor. Biol. 162 (1993) 447] to describe the influence of a(w) on fungal development. An excellent correlation between the experimental data and the model predictions was obtained, the regression coefficients (r2) were …
Inactivation of conidia of Penicillium chrysogenum, P. digitatum and P. italicum by ethanol solutions and vapours
2008
A fractional factorial design, 2(5-1) experiments, was used for assessing the influence of 5 factors: water activity, aw [0.7, 0.9], temperature, T ( degrees C) [10, 30], mode of application, A [liquid, vapour], ethanol concentration, E (% w/w) [5, 10] and time, t (d) [1, 4] on the inactivation of spores of Penicillium chrysogenum, P. digitatum and P. italicum. Survival was determined by germination at optimal conditions within 3d. The experimental response was log (N 0/Nt), where N 0 and Nt (spore ml(-1)) the concentrations of viable spores at t=0 and t respectively. By a decreasing order of sensitivity to ethanol, moulds were ranked as followed: P. digitatum, P. italicum and P. chrysogenu…
Modeling the heat inactivation of foodborne pathogens in milk powder : High relevance of the substrate water activity
2017
International audience; Due to the ability of foodborne pathogens to survive in low moisture foods, the decontamination of these products is an important issue in food hygiene. Up to now, such decontamination has mostly been achieved through empirical methods. The intention of this work is to establish a more rational use of heat treatment cycles. The effects of thermal treatment cycles on the inactivation of dried Salmonella Typhimurium, Salmonella Senftenberg, Cronobacter sakazakii and Escherichia coli were assessed. Bacteria were mixed with whole milk powder and dried down to different water activity levels (0.11, 0.25, 0.44 and 0.58). The rate of inactivated bacteria was determined afte…
Lag time for germination of Penicillium chrysogenum conidia is induced by temperature shifts.
2013
In the environment, fungal conidia are subject to transient conditions. In particular, temperature is varying according to day/night periods. All predictive models for germination assume that fungal spores can adapt instantaneously to changes of temperature. The only study that supports this assumption (Gougouli and Koutsoumanis, 2012, Modelling germination of fungal spores at constant and fluctuating temperature conditions. International Journal of Food Microbiology, 152: 153-161) was carried out on Penicillium expansum and Aspergillus niger conidia that, in most cases, already produced germ tubes. In contrast, the present study focuses on temperature shifts applied during the first stages…
Modeling in Microbial Ecology
2014
SPE IPM; International audience; The bases and the principles of modeling in microbial community ecology and biogeochemistry are presented and discussed. Several examples are given. Among them, the fermentation process is largely developed, thus demonstrating how the model allows determining the microbial population growth rate, the death rate, and the maintenance rate. More generally, these models have been used to increase the development of bioenergetic formulations which are presently used in biogeochemical models (Monod, Droop, DEB models). Different types of interactions (competition, predation, and virus–bacteria) are also developed. For each topic, a complete view of the models used…
Control of food spoilage fungi by ethanol
2011
This review discusses the effects of ethanol on the inhibition of growth and germination of fungi and on the inactivation of fungal spores. After a brief survey on the impact of spoilage fungi on the economy and food quality, the major applications of ethanol in controlling fruit decay and extending the shelf-life of food products are reviewed. Many parameters including minimum inhibitory concentration (MIC) and D-values for various moulds are included. The thermodynamic relationship between the liquid phase and the headspace and the mode of action of ethanol on fungi are explained. Due to their promising use as a fumigant, special attention is paid to ethanol vapours.
Effect of inoculum size and water activity on the time to visible growth of Penicillium chrysogenum colony.
2012
In order to assess the effect of the inoculum size on the time to visible growth for Penicillium chrysogenum, the correlation described by Gonzalez et al. (Gonzalez, H.H.L., Resnik, S.L., Vaamonde, G., 1987. Influence of inoculum size on growth rate and lag phase of fungi isolate from Argentine corn. International Journal of Food Microbiology 4, 111-117) was compared to the model introduced by Gougouli et al. (Gougouli, M., Kalantzi, K., Beletsiotis, E., Koutsoumanis, K.P., 2011. Development and application of predictive models for fungal growth as tools to improve quality control in yogurt production. Food Microbiology 28, 1453-1462). Based on the regression coefficient, the latter model p…
Modelling the effect of ethanol on growth rate of food spoilage moulds
2005
The effect of ethanol (E) on the radial growth rate (mu) of food spoilage moulds (Aspergillus candidus, Aspergillus flavus, Aspergillus niger, Cladosporium cladosporioides, Eurotium herbariorum, Mucor circinelloides, Mucor racemosus, Paecilomyces variotii, Penicillium chrysogenum, Penicillium digitatum, Rhizopus oryzae and Trichoderma harzianum) was assessed in Potato Dextrose Agar (PDA) medium at a(w) 0.99, 25 degrees C. In order to model this effect, the Monod type equation described previously by Houtsma et al. (Houtsma, P.C., Kusters, B.J.M., de Wit, J.C., Rombouts, F.M., Zwietering, M.H., 1994. Modelling growth rates of Listeria monocytogenes as a function of lactate concentration. Int…
Modeling the effect of ethanol vapor on the germination time of Penicillium chrysogenum.
2005
The influence of ethanol vapor on germination of Penicillium chrysogenum was determined on yeast nitrogen base plus glucose agar medium at 25 degrees C. Ethanol vapors were generated by 0 to 6% (wt/wt) ethanol solutions at the bottom of hermetically closed petri dishes. The logistic equation was used to describe the data as the percentage of germination versus time and to estimate the germination time. The effect of ethanol concentration on germination time was described by a new reparameterized equation, resulting in an estimated limiting ethanol concentration of 4.3%. Up to 3% ethanol, all spores germinated, and the germination time increased with increasing ethanol concentration. At 3.5 …
Validation of a predictive model for the growth of Botrytis cinerea and Penicillium expansum on grape berries.
2010
The objective of this study was to develop and to validate a model for predicting the combined effect of temperature and a(w) on the radial growth rate, mu, of Botrytis cinerea and Penicillium expansum on grape berries. The proposed strategy was based on the gamma-concept developed previously [Zwietering, M.H., Wijtzes, T., de Wit, J.C., van't Riet, K. 1992. A decision support system for prediction of the microbial spoilage in foods. Journal of Food Protection. 12, 973-979]: mu=mu(opt).gamma(T).gamma(a(w)), where the gamma functions were cardinal models with inflection (CMI), mu(opt) the radial growth rate on grape berries. Firstly, the cardinal temperatures and a(w)'s were estimated indepe…
Use of the Weibull model to describe inactivation of dry harvested conidia of different Penicillium species by ethanol vapours
2010
Aims: This study aimed at modelling the effect of ethanol vapours, in the range 0·7–7·5 kPa, on the inactivation of dry-harvested conidia of Penicillium chrysogenum, Penicillium digitatum and Penicillium italicum. Methods and Results: Survival curves were modelled by a Weibull model: log (N/N0) = −1/2·303 (t/α)β. The shape parameter β was different from one in all cases, indicating that the classical first-order kinetics approach is the exception rather than the rule. Survival curves exhibited upward concavity (β < 1) with the notable exception of P. chrysogenum at ethanol vapour pressures 0·7 and 1·5 kPa. The scale parameter α (h) varied greatly depending on the ethanol vapour pressure a…
Preparation of fungal conidia impacts their susceptibility to inactivation by ethanol vapours.
2009
Abstract A common protocol employed for the preparation of conidia employs flooding a fungal colony grown on semi-solid media under optimum conditions with an aqueous solution. In contrast, conidia produced in a natural environment are usually not hydrated when disseminated in air and can be produced under water stress. In order to simulate the latter conditions, cultures were grown at different water activities and conidia were dry-harvested on the lid by turning the dishes upside-down then gently tapping the bottom of the box. This study aimed at assessing the effect of the preparation of fungal conidia on their inactivation by ethanol vapours. Firstly ethanol vapours (either 0.30 or 0.45…
Standardisation of methods for assessing mould germination: a workshop report.
2006
International audience; The first workshop on predictive mycology was held in Marseille, France, 2–4 February 2005 under the auspices of the French Microbiological Society. The purpose of the workshop was to list the different techniques and definitions used by scientists for assessing mould germination and to evaluate the influence of the different techniques on the experimental results. Recommendations were made when a large consensus was obtained. In order to facilitate the study of germination, alternative methods to microscopic examination were examined.
Effect of storage conditions (relative humidity, duration, and temperature) on the germination time of Aspergillus carbonarius and Penicillium chryso…
2012
Fungal conidia are disseminated, often in the air, for a certain period of time, prior to contaminating food products. The objective of this study was to examine the effects of the relative humidity, RH (%), time (day), and temperature (°C) during this period of time, called "storage", on the germination time, τ (h), of Aspergillus carbonarius and Penicillium chrysogenum. A Doehlert design was used in the range, 20-100% RH, 2-28 days, and 5-25 °C. As compared to un-stored conidia, the germination time of conidia stored at 60% RH, 15 days, 5 °C was increased by 23 and 28%, for A. carbonarius and P. chrysogenum, respectively. Stored conidia exhibited a minimum τ value at 60% RH, and 100% RH f…
Modelling the effect of temperature, pH, water activity, and organic acids on the germination time of Penicillium camemberti and Penicillium roquefor…
2017
International audience; In this study, the influence of environmental factors on the germination time of Penicillium camemberti and Penicillium roqueforti conidia was evaluated. To do so, the effects of i/temperature, pH, water activity, and ii/organic acids were determined using models based on i/cardinal values, and ii/minimum inhibitory concentration (MIC) respectively. Cardinal values for germination of conidia were not observed to be species dependent. Minimum temperatures were estimated to be below the freezing point, with an optimum of 26.9 degrees C, and a maximum of 33.5 degrees C. For both species, minimal and optimal a(w) values were found to be 0.83 and 0.99, respectively, while…
The logarithmic transformation should be avoided for stabilising the variance of mould growth rate.
2007
Abstract Radial growth rate, μ (mm d − 1 ) was evaluated by plotting the radius of the colony, r (mm) versus time (d) for Alternaria alternata , Aspergillus flavus , Cladosporium cladosporioides , Mucor racemosus , Rhizopus oryzae and Trichoderma harzianum at different T and a w . For each of the 12 data sets, an analysis of variance of the raw growth rate data was performed. It was observed from the P -values that all square-root transformed values of μ were non-significant at the significance level α = 0.05, whereas for untransformed values of μ , three of the 12 values were significant and for logarithmically transformed μ , nine of the 12 values were significant at the significance lev…
Significance of the physiological state of fungal spores.
2008
In predictive mycology, most of the studies have been concerned with the influence of some environmental factors on fungal growth and production of mycotoxins, at steady-state. However, fluctuating conditions, interactions between organisms, and the physiological state of the organisms may also exert a profound influence on fungal responses in food and in the environment. In the laboratory, fungal spores are widely used as a biological material. They are produced under optimal conditions then, partially re-hydrated for obtaining standardized spore suspensions. In real conditions, spores are produced under suboptimal conditions and can be submitted to various stresses prior to their germinat…
Prediction of conidial germination of Penicillium chrysogenum as influenced by temperature, water activity and pH.
2001
M. SAUTOUR, A. ROUGET, P. DANTIGNY, C. DIVIES AND M. BENSOUSSAN. 2001 Aims: Conidial germination of Penicillium chrysogenum was carried out under operating conditions compatible with a pastries manufacturing process. Methods and Results: A range, limited by two experimental values, was defined for each environmental factor tested: temperature (15 or 25°C), water activity (0·75 or 0·85) and pH (3·5 or 5·5). A closed device was made, which maintained an equilibrium between water activity of the culture medium and atmospheric relative humidity during 25 days, to follow spore germination. The combined effects of temperature, water activity and pH on spore germination were studied by applying fa…
Validation of a predictive model for the growth of chalk yeasts on bread.
2015
The present study focused on the effects of temperature, T, and water activity, aw, on the growth of Hyphopichia burtonii, Pichia anomala, and Saccharomycopsis fibuligera on Sabouraud Agar Medium. Cardinal values were estimated by means of cardinal models with inflection. All the yeasts were xerophilic, and they exhibited growth at 0.85 aw. The combined effects of T, aw, and pH on the growth of these species were described by the gamma-concept and validated on bread in the range of 15-25 °C, 0.91-0.97 aw, and pH 4.6-6.8. The optimum growth rates on bread were 2.88, 0.259, and 1.06 mm/day for H. burtonii, P. anomala, and S. fibuligera, respectively. The optimal growth rate of S. fibuligera o…
Inoculation of airborne conidia of Penicillium chrysogenum on the surface of a solid medium
2016
International audience; To reproduce a fungal contamination of food products by airborne conidia, a method to inoculate a few number (in the range 1-9) of conidia on the surface of agar media was developed. This technique would allow to determine accurately the time to detection of fungal colonies, then the mould free shelf-life of food products by using dry conidia. The method was based on dry-harvesting the conidia in the lid by gently taping the bottom of the dishes where sporulating mycelium was grown, retaining the conidia on glass beads, and, aseptically transferring the beads to successive Petri dishes to "dilute" the samples. Among the eleven factors tested by means of an experiment…
Active packaging with antifungal activities.
2016
International audience; There have been many reviews concerned with antimicrobial food packaging, and with the use of antifungal compounds, but none provided an exhaustive picture of the applications of active packaging to control fungal spoilage. Very recently, many studies have been done in these fields, therefore it is timely to review this topic. This article examines the effects of essential oils, preservatives, natural products, chemical fungicides, nanopartides coated to different films, and chitosan in vitro on the growth of moulds, but also in vivo on the mould free shelf-life of bread, cheese, and fresh fruits and vegetables. A short section is also dedicated to yeasts. All the ap…
A model for the effect of pH on the growth of chalk yeasts.
2013
Hyphopichia burtonii, Pichia anomala, and Saccharomycopsis fibuligera were isolated from spoiled packaged sliced bread. These chalk yeasts were characterized by a wide range of pH for which growth was almost optimum. Thus, the curve growth vs pH exhibited plateau and sharp profiles close to the minimum and the maximum pH. This study described a chalk yeast model (CYM) for the effect of pH derived from a new germination model for fungi (Dantigny, P., Nanguy, S., P.-M., Judet-Correia, D., and Bensoussan, M. 2011, International Journal of Food Microbiology, 146, 176-181). The CYM is asymmetric, versatile, based on parameters with biological significance, and compatible with the gamma concept. …
Basis of predictive mycology.
2005
Abstract For over 20 years, predictive microbiology focused on food-pathogenic bacteria. Few studies concerned modelling fungal development. On one hand, most of food mycologists are not familiar with modelling techniques; on the other hand, people involved in modelling are developing tools dedicated to bacteria. Therefore, there is a tendency to extend the use of models that were developed for bacteria to moulds. However, some mould specificities should be taken into account. The use of specific models for predicting germination and growth of fungi was advocated previously [ Dantigny, P., Guilmart, A., Bensoussan, M., 2003. Basis of predictive mycology. In Proceedings of the 4th Internatio…
Impact of water activity of diverse media on spore germination of Aspergillus and Penicillium species
2010
International audience; The effects of water activity (aw) of diverse media i/ culture medium for sporogenesis, aw sp ii/ liquid spore suspension medium, aw su and iii/ medium for germination, aw ge, on the germination time tG of Aspergillus carbonarius, Aspergillus flavus, Penicillium chrysogenum and Penicillium expansum were assessed according to a screening matrix at 0.95 and 0.99 aw. It was shown that i/ reduced tGs were obtained at 0.95 aw sp except for P. expansum ii/ a significant effect of aw su on tG was demonstrated for A. carbonarius, P. chrysogenum and P. expansum iii/ the most important factor for controlling the germination time was the medium for germination except for A. car…
Modelling the inhibitory effect of copper sulfate on the growth of Penicillium expansum and Botrytis cinerea
2011
Aims: This study aimed to investigate the effect of copper sulfate (from 0 to 8 mmol kg−1) on radial growth rate and lag time of two moulds responsible for vine grapes spoilage: Penicillium expansum strain 25·03 and Botrytis cinerea, strains BC1 and BC2. Methods and results: A new model was developed to describe tailing and shoulders in the inhibition curves. Because of tailing, the minimum inhibitory concentration (MIC), was not defined as the concentration at which no growth was observed, but as the concentration at which the lag time was infinite. The concentrations at which μ = μopt/2, (Cu50), were in the range of 2·2–2·6 mmol kg−1. Radial growth rate of P. expansum and the reciprocal…
Long-term survival of pathogenic and sanitation indicator bacteria in experimental biowaste composts
2005
ABSTRACT For economic, agricultural, and environmental reasons, composting is frequently used for organic waste recycling. One approach to limiting the potential risk from bacterial food-borne illnesses is to ensure that soil amendments and organic fertilizers are disinfected. However, more knowledge concerning the microbiological safety of composted substrates other than sludge and manure is necessary. Experimental in-vessel biowaste composts were used to study the survival of seeded Listeria monocytogenes , Salmonella enterica subsp. enterica serotype Enteritidis, and Escherichia coli . Four organic waste mixtures, containing various proportions of paper and cardboard, fruits and vegetabl…
A new model for germination of fungi.
2010
Abstract The objective of this study was to design a germination model dedicated to fungi. The percentage of germinated spores, P(%), depended on the maximum percentage of germination P max (%), the germination time, τ (h) and a design parameter, d (-) according to : P = P max 1 − 1 1 + t τ d . The model was capable to fit satisfactorily either apparent symmetric and asymmetric shapes of germination curves. The accuracy of τ determined by using the logistic or the present model was at least twice that obtained by the Gompertz equation. In contrast to the logistic model, the new model is by essence asymmetric. Therefore, its use is consistent with skewed distributions of the individual germi…
Indigenous Listeria spp. in biowastes and during composting
2007
International audience