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Clermont-Ferrand, France

Coroller L.,CNRS Microbial Ecology | Jeuge S.,French Institute for Pig and Pork Products | Couvert O.,CNRS Microbial Ecology | Christieans S.,ADIV | Ellouze M.,French Institute for Pig and Pork Products
Food Microbiology | Year: 2014

The process of dried fermented sausages is recognized to be favourable to the reduction of the Salmonella population. The objective of this study was to develop a model describing the evolution of Salmonella during the fabrication process of dried sausages and to optimize the food formulation to prevent pathogen presence at the end of the process.An experimental design was set to investigate the effects of the fermentation and drying process for several formulations, taking into account the type of starter culture, the sodium chloride concentration, the dextrose and lactose concentration on the Salmonella Typhimurium strain behaviour.A growth-inactivation model based on the gamma concept was then developed to quantify Salmonella behaviour in dynamic process conditions of temperature, pH, lactic acid and water activity. This behaviour was characterized by a first growth step, followed by an inactivation step. The Salmonella fate was well described by the model in terms of population size variation and transition from growth to inactivation. The Salmonella behaviour was influenced by the initial sugar concentration and the starter type but not by sodium chloride content. This model can be a valuable tool to design the food process and formulation to control Salmonella. © 2014 Elsevier Ltd. Source

Harkouss R.,French National Institute for Agricultural Research | Astruc T.,French National Institute for Agricultural Research | Lebert A.,CNRS Pascal Institute | Gatellier P.,French National Institute for Agricultural Research | And 5 more authors.
Food Chemistry | Year: 2015

Temperature, salt and water contents are key processing factors in dry-cured ham production. They affect how proteolysis, lipid oxidation, structure and texture evolve, and thus determine the sensory properties and final quality of dry-cured ham. The aim of this study was to quantify the interrelationships and the time course of (i) proteolysis, (ii) lipid oxidation, (iii) five textural parameters: hardness, fragility, cohesiveness, springiness and adhesiveness and (iv) four structural parameters: fibre numbers, extracellular spaces, cross section area, and connective tissue area, during the dry-cured ham process. Applying multiple polynomial regression enabled us to build phenomenological models relating proteolysis, salt and water contents to certain textural and structural parameters investigated. A linear relationship between lipid oxidation and proteolysis was also established. All of these models and relationships, once combined with salt penetration, water migration and heat transfer models, can be used to dynamically simulate all of these phenomena throughout dry-cured ham manufacturing. © 2014 Elsevier Ltd. All rights reserved. Source

Oillic S.,French National Institute for Agricultural Research | Lemoine E.,ADIV | Gros J.-B.,University Blaise Pascal | Kondjoyan A.,French National Institute for Agricultural Research
Meat Science | Year: 2011

Cooking loss kinetics were measured on cubes and parallelepipeds of beef Semimembranosus muscle ranging from 1. cm × 1. cm × 1. cm to 7. cm × 7. cm × 28. cm in size. The samples were water bath-heated at three different temperatures, i.e. 50 °C, 70 °C and 90 °C, and for five different times. Temperatures were simulated to help interpret the results. Pre-freezing the sample, difference in ageing time, and in muscle fiber orientation had little influence on cooking losses. At longer treatment times, the effects of sample size disappeared and cooking losses depended only on the temperature. A selection of the tests was repeated on four other beef muscles and on veal, horse and lamb Semimembranosus muscle. Kinetics followed similar curves in all cases but resulted in different final water contents. The shape of the kinetics curves suggests first-order kinetics. © 2011 The American Meat Science Association. Source

Chaillou S.,French National Institute for Agricultural Research | Chaillou S.,Agro ParisTech | Chaulot-Talmon A.,French National Institute for Agricultural Research | Chaulot-Talmon A.,Agro ParisTech | And 25 more authors.
ISME Journal | Year: 2015

The microbial spoilage of meat and seafood products with short shelf lives is responsible for a significant amount of food waste. Food spoilage is a very heterogeneous process, involving the growth of various, poorly characterized bacterial communities. In this study, we conducted 16S ribosomal RNA gene pyrosequencing on 160 samples of fresh and spoiled foods to comparatively explore the bacterial communities associated with four meat products and four seafood products that are among the most consumed food items in Europe. We show that fresh products are contaminated in part by a microbiota similar to that found on the skin and in the gut of animals. However, this animal-derived microbiota was less prevalent and less abundant than a core microbiota, psychrotrophic in nature, mainly originated from the environment (water reservoirs). We clearly show that this core community found on meat and seafood products is the main reservoir of spoilage bacteria. We also show that storage conditions exert strong selective pressure on the initial microbiota: alpha diversity in fresh samples was 189±58 operational taxonomic units (OTUs) but dropped to 27±12 OTUs in spoiled samples. The OTU assemblage associated with spoilage was shaped by low storage temperatures, packaging and the nutritional value of the food matrix itself. These factors presumably act in tandem without any hierarchical pattern. Most notably, we were also able to identify putative new clades of dominant, previously undescribed bacteria occurring on spoiled seafood, a finding that emphasizes the importance of using culture-independent methods when studying food microbiota. © 2015 International Society for Microbial Ecology. Source

Coton E.,ADRIA NORMANDIE | Desmonts M.-H.,AERIAL | Leroy S.,French National Institute for Agricultural Research | Coton M.,ADRIA NORMANDIE | And 5 more authors.
International Journal of Food Microbiology | Year: 2010

In this study, the biodiversity of Coagulase-Negative Staphylococci (CNS) strains isolated in France from cheese related samples (227 isolates) and dry sausage related samples (204 isolates) was compared to the biodiversity of 297 clinical isolates. Species identification was performed using different molecular methods (specific PCR, "Staph array" hybridization and sodA gene sequencing). Infraspecific biodiversity of strains belonging to the main CNS species found in both food and clinical samples was then assessed by pulse-field gel electrophoresis (PFGE). For food-related samples, the main species encountered corresponded to Staphylococcus equorum (28.5%), S. xylosus (28.3%), S. saprophyticus (12.5%) and S. succinus (7.7%); while, for clinical isolates, the main species encountered corresponded to S. epidermidis (69.4%), S. capitis (9.8%), S. hominis (4.5%), S. warneri (4.5%) and S. haemolyticus (3.8%). The two main species common to both food and clinical samples corresponded to S. epidermidis and S. saprophyticus. Concerning infraspecific biodiversity, PFGE profiles of S. equorum, S. saprophyticus and S. epidermidis showed a large genomic biodiversity. Comparatively, S. xylosus exhibited a lower biodiversity. No correlation could be observed between PFGE patterns and either the geographical origin or the sample type. This study highlighted that no food strains had similar PFGE profiles to clinical ones and that the two main food-related species, S. equorum and S. xylosus, were not found in clinical samples. The identification of CNS species and the characterisation of the genetic diversity of the strains constitute a first step towards CNS safety assessment. © 2009 Elsevier B.V. All rights reserved. Source

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