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New approaches, mainly based on mass spectrometry techniques, are being developed and appear as a must in the modern food science and microbiology research to investigate food quality and safety. To date, the investigation of cheese ripening mechanisms has mostly used targeted approaches. The aims of the present project were to assess the use of untargeted metabolomics as an approach to investigate the influence of altering one ripening parameter to generate fine differences in the microbial metabolism within cheese. Two cheeses were made which varied with respect to the spatial distribution of bacterial colonies, leading to cheeses with only big or only small colonies. Liquid chromatography high resolution mass spectrometry metabolic fingerprints were acquired on cheese extracts collected after 2, 13 and 27 days of ripening using two different extraction methods (water or acetonitrile) and analyzed using two different simultaneous ionization modes (positive and negative electrospray). Data processing involving XCMS and multivariate statistical analysis highlighted significant discriminant profiles of the cheese metabolomes according to the two different spatial distributions compared. The different fractions investigated (water and acetonitrile extractions in two ionization modes) were complementary and resulted in a view as global as possible of the cheese metabolome which had been modulated by the spatial distribution of bacterial colonies. Some of the metabolites were then identified using an in-house database. These results show the relevance of cheese LC–HRMS fingerprinting to understand the influence of a ripening parameter generating fine differences on microbial metabolism within cheese.

Lactic acid bacteria (LAB) and propionic acid bacteria (PAB) are widely used in the manufacture of cheeses and other fermented dairy products. Bacterial species used as starters are mainly chosen according to their intrinsic properties: the milk acidifying capacity for LAB starters and the aromatizing properties of PAB, for example. Beyond the general characteristics of a bacterial species, many key phenotypic traits determining their interest for dairy applications depend on the strain within a given species. Through some examples, this review illustrates how the choice of a bacterial strain with specific technological characteristics, within a given species of LAB or PAB, can determine the final properties in the end product. This concerns the technological properties of cheeses, such as flavour, texture, and opening formation, and their functional properties, such as inhibition of undesirable microorganisms and health properties. When known, the genetic determinants of the diversity are presented. This review emphasizes the importance of preserving and exploring microbial resources at the intraspecific level, as an unending source of diversity for innovation in food fermentation.

Le développement de la production laitière dans la région transamazonienne, dans le nord du Brésil, est chargé d'enjeux sociaux dans la mesure où cette activité pourrait permettre de consolider des systèmes de production agricole familiaux, fragilisés depuis trente ans par un environnement économique précaire. Cette alternative a cependant du mal à se concrétiser mais la commune de Brasil Novo fait figure d'exception, car depuis plus de vingt ans un bassin laitier se maintient, avec une production permanente de fromages. L'intérêt de l'approche présentée ici est d'une part de se placer sur le temps long pour appréhender les étapes, conditions et synergies pour la mise en place et le maintien d'un bassin laitier, et d'autre part de s'intéresser aux interactions entre trois systèmes déterminants pour le bassin laitier. Nous analysons ensemble (i) les systèmes d'élevage dans leur diversité ; (ii) la filière laitière, en particulier les conditions d'achats de la matière première au producteur et de transformation en fromages ; (iii) le territoire, dans ses dimensions physiques (relief, distances, saisons…), humaines (origine culturelle des éleveurs, savoir-faire, législations sanitaires…) et d'aménagement (infrastructures, énergie). Basée sur dix années de collecte d'informations sur le terrain, la méthode s'appuie sur une analyse typologique des systèmes de production laitière, une analyse fonctionnelle de la filière et du territoire, ainsi qu'une analyse rétrospective et prospective du bassin laitier. Elle met en évidence trois séquences successives d'évolution, ainsi que les facteurs de changement et de résistance. Deux modèles émergents sont décrits, mais l'article souligne la vulnérabilité de cette dynamique laitière, face aux puissantes dynamiques territoriales, notamment foncières et démographiques, que le grand chantier hydroélectrique génère dans la commune voisine d'Altamira.

Food products are complex matrices. They contain molecules from several families that interact with each other to generate specific structures and functionalities. These molecules may include proteins and peptides resulting from protein hydrolysis, e.g. in cheese. It is still difficult to establish a clear relationship between a pool of peptides and their techno-functionalities such as emulsifying, foaming, gelling or even texture properties within a complex matrix. Among the data usually known, there is the degree of hydrolysis that provides information about the average size of the peptides formed. A high degree of hydrolysis induces the production of a pool of small-size peptides (less than 20 amino acids). Advances in identification methods have made the identification of peptides present in food products possible. The size, charge, hydropathy index and isoelectric point of the peptide, as well as its secondary structure, can be calculated on the basis of the peptide sequence. The aim of this study was to determine which physicochemical and structural characteristics of peptides are involved in the cheese stretchability. This work is a re-evaluation, using multivariate exploratory analysis, of the experimental data obtained from a former study (Sadat-Mekmene et al., 2013) in which one typical functionality criterion of Swiss-type cheese (stretchability) was measured and peptides were identified. This methodology, based on Principal Component Analysis and Correspondence Analysis, is one way to establish a relationship between peptide characteristics and their techno-functional property within a complex dairy matrix. This statistical approach showed that the peptides predominantly involved in cheese stretchability were a mixture of both hydrophobic and hydrophilic peptides and that they are large enough to interact with each other and with native proteins. This approach could be applied to better understand the impact of peptides on various food matrices and food techno-functionalities.

Unlike other dairy products, camel cheese processing is recent. Thanks to recombinant camel chymosin, camel cheese making is easier. In Saudi Arabia, camel cheese making was developed for last 4 years in the Camel project (FAO project). Our cheeses are made with fresh milk strictly controlled for their microbiological quality (coliform, total flora). The milk composition is known, all samples being analyzed with Milkoscan-FOSS FT1 ©. Different starters are used from Coquard © (France) according to the type of cheese expected. All along the process, the pH is checked (draining, moulding, pressing, salting). The composition of the whey is also determined. At the end of the process, after salting, dry matter and final pH are measured as well as the total yield. Cheese of Haloumi type are pasteurized in their whey and packaged under vacuum. Some cheeses are ripening in special cave for few weeks (Mozzarella, Feta) or months (Camembert, Saint- Paulin). The cheese yield is depending of the cheese type but occurs between 8 and 12%. Sensory tests are performed. These cheeses are available on the market. Different experiments are performed in order to test the effect of different starters.

Cheeses and other fermented dairy products constitute a tremendous source of live and active bacteria in our diet. Depending on the product, on the strain and on the health status of individuals, this major bacterial intake can have beneficial effects, or not! Recognized molecular, cellular and animal models have been developed to detect and study probiotic bacterial strains. These tools may also reveal unexpected probiotic potential in bacterial strains within the tremendous biodiversity present in traditional fermented products. In our team, we focused on dairy propionibacteria, taking advantage of a unique biological resource center. Propionibacterium freudenreichii is a beneficial bacterium used in the food industry as a vitamin producer, as a bio-preservative and as a cheese ripening starter. We hypothesized that strains considered for techno-functional reasons (aroma, texture), may also play a beneficial role as probiotics. Food-grade dairy propionibacteria are nutraceutical producers. They release short chain fatty acids (SCFAs), folic acid and cobalamin, which play a role in intestinal physiology. SCFAs induce apoptosis via the mitochondrial death pathway. We investigate the potential of dairy propionibacteria-fermented products to synergize with drugs used in gastric and colorectal cancer. Some strains are known to adhere to intestinal epithelial cells and mucus and to modulate important functions of the gut mucosa, including cell proliferation and immune response. Selected strains show promising immunomodulatory properties with an anti-inflammatory protective evidenced effect in vitro and in vivo. We thus developed experimental monoxenic fermented dairy products, exclusively fermented by an anti-inflammatory selected strain of P. freudenreichii. Key surface proteins, involved in its immunomodulatory effects, are expressed within these products. Their consumption exerted an anti-inflammatory effect in vivo. These results open new perspectives in the field of prevention and/or treatment of intestinal cancer (CRC) and inflammatory diseases (IBD). The synergy with pro-apoptotic chemotherapy molecules suggests that such a fermented product, or the Propionibacterium alone, may be proposed as a food supplement to enhance the effects of anticancer treatments. The preventive effect in the context of induced colitis suggests that it could potentialize IBD treatment. This work reveals an unexpected probiotic potential in industrial dairy propionibacteria starters. It opens exciting perspectives in a context of growing occurrence of IBD, multifactor diseases related to diet, and provides a new functional fermented product for preclinical and clinical studies aimed at prevention or treatment of IBD.

Phosphorus is a critical dietary mineral that is involved as phosphate in bone, tooth, nucleic acids or phospholipids and is mainly supplied through consumption of dairy products. Hence, it is important to be able to accurately and efficiently assay phosphate in dairy products. Currently, a colorimetric International Standard Organisation (ISO) reference method is used to assay phosphate in milk and cheese. This method requires large amounts of samples, of harmful chemicals and of manpower. In this paper, ionic exchange chromatography was used to assay phosphate on acid milk ultrafiltration permeate, milk, various cheeses and processed cheese and compared to the ISO method. The chromatographic method requires little amounts of materials and is automated. On the other hand, accuracy and precision were found to be less than those obtained with the reference method. In particular, phosphate was underestimated by the chromatographic method. Therefore, the chromatographic method is currently competitive for comparative assays, but not for absolute quantitation of phosphate. Research is still needed to fully upgrade the performances of this environment-friendly and time-saving method to those of the ISO reference.

Dairy propionibacteria are actinomycetales found in various fermented food products. The main species, Propionibacterium freudenreichii , is generally recognized as safe and used both as probiotic and as cheese starter. Its probiotic efficacy tightly depends on its tolerance towards digestive stresses, which can be largely modulated by the ingested delivery vehicle.Indeed, tolerance of this bacterium is enhanced when it is consumed within a fermented dairy product, compared to a dried probiotic preparation. We investigated both stress toler- ance and protein neosynthesis upon growth in i) chemically defined or ii) aqueous phase of Emmental cheeses. Although the same final population level was reached in both media, a slower growth and an enhanced survival of CIRM BIA 1 strain of P. freudenreichii subsp. shermanii was observed in Emmental juice, compared to chemically defined medium. This was accompanied by differences in substrates used and products released as well as over- expression of various early stress adaptation proteins in Emmental juice, compared to chem-ically defined medium, implied in protein folding, in aspartate catabolism, in biosynthesis ofvaline, leucine and isoleucine, in pyruvate metabolism in citrate cycle, in the propionate metabolism, as well as in oxidoreductases. All these changes led to a higher digestive stress tolerance after growth in Emmental juice. Mechanisms of stress adaptation were induced in this environment, in accordance with enhanced survival. This opens perspectives for the use of hard and semi-hard cheeses as delivery vehicle for probiotics with enhanced efficacy

Domestication is an excellent model for studies of adaptation because it involves recent and strong selection on a few, identified traits [1-5]. Few studies have focused on the domestication of fungi, with notable exceptions [6-11], despite their importance to bioindustry [12] and to a general understanding of adaptation in eukaryotes [5]. Penicillium fungi are ubiquitous molds among which two distantly related species have been independently selected for cheese making-P. roqueforti for blue cheeses like Roquefort and P. camemberti for soft cheeses like Camembert. The selected traits include morphology, aromatic profile, lipolytic and proteolytic activities, and ability to grow at low temperatures, in a matrix containing bacterial and fungal competitors [13-15]. By comparing the genomes of ten Penicillium species, we show that adaptation to cheese was associated with multiple recent horizontal transfers of large genomic regions carrying crucial metabolic genes. We identified seven horizontally transferred regions (HTRs) spanning more than 10 kb each, flanked by specific transposable elements, and displaying nearly 100% identity between distant Penicillium species. Two HTRs carried genes with functions involved in the utilization of cheese nutrients or competition and were found nearly identical in multiple strains and species of cheese-associated Penicillium fungi, indicating recent selective sweeps; they were experimentally associated with faster growth and greater competitiveness on cheese and contained genes highly expressed in the early stage of cheese maturation. These findings have industrial and food safety implications and improve our under-standing of the processes of adaptation to rapid environmental changes.

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During cheese processing and ripening, bacteria develop as colonies. Substrates and metabolites must then diffuse either from or into the colonies. Exploring how the inner Q1 Q2 cells of the colony access the substrates or get rid of the products leads to study the Q7 Q8 diffusion of solutes inside bacterial colonies immobilized in cheese. Diffusion limitations of substrates within the bacterial colony could lead to starvation for the cells in the center of the colony. This study aimed at better understands ripening at the colony level, by investigating how diffusion phenomena inside colonies vary depending on both the physicochemical properties of the solutes and Lactococcus lactis strain. Dextrans (4, 70, and 155 kDa) and milk proteins (BSA, lactoferrin and aS1-casein) of different sizes and physicochemical properties were chosen as model of diffusing solutes, and two L. lactis strains presenting different surface properties were immobilized as colonies in a model cheese. Diffusion of solutes inside and around colonies was experimentally followed by time-lapse confocal microscopy. Dextran solutes diffused inside both lactococci colonies with a non-significantly different effective diffusion coefficient, which depended mainly on size of the solute. However, whereas flexible and neutral hydrophilic polymers such as dextran can diffuse inside colonies whatever its size, none of the three proteins investigated in this study could penetrate inside lactococci colonies. Therefore, the diffusion behavior of macromolecules through bacterial colonies immobilized in a model cheese did not only depends on the size of the diffusing solutes, but also and mainly on their physicochemical properties. Milk caseins are probably first hydrolyzed by the cell wall proteases of L. lactis and/or other proteases present in the cheese, and then the generated peptides diffuse inside colonies to be furthermetabolized into smaller peptides and amino acids by all the cells located inside the colonies.

In Saudi Arabia, the camel is representing the old generations while technology is presenting the new generation. However, two generations are mixed together to keep old culture in modern form. For these, we started to build information system to save and process data collected in camels. This database using Access tool is the start point for establishing a convenient control of performances of our animals. Our database is including five main items regarding identification (camel characteristics), reproduction (mating and calving events), milk production (individual produced quantity including milk flow), milk composition (12 parameters), milk processing (pasteurization, cheese making) and diseases. This relational database allows assuming a regular monitoring of all performances, a primary step for implementing a selection program and contributing to the genetic improvement of the species. The present paper is describing the Conceptual Model of the Data and shows some potentialities for data treatment.

Bacteria and yeasts are important sensory factors of raw-milk cheeses as they contribute to the sensory richness and diversity of these products. The diversity and succession of yeast populations in three traditional Registered Designation of Origin (R.D.O.) Salers cheeses have been determined by using phenotypic diagnoses and Single-Strand Conformation Polymorphism (SSCP) analysis. Isolates were identified by phenotypic tests and the sequencing of the D1–D2 domains of the 26S rRNA gene. Ninety-two percent of the isolates were identified as the same species in both tests. Yeast-specific primers were designed to amplify the V4 region of the 18S rRNA gene for SSCP analysis. The yeast species most frequently encountered in the three cheeses were Kluyveromyces lactis , Kluyveromyces marxianus , Saccharomyces cerevisiae , Candida zeylanoides and Debaryomyces hansenii . Detection of less common species, including Candida parapsilosis , Candida silvae , Candida intermedia , Candida rugosa, Saccharomyces unisporus, and Pichia guilliermondii was more efficient with the conventional method. SSCP analysis was accurate and could be used to rapidly assess the proportions and dynamics of the various species during cheese ripening. Each cheese was clearly distinguished by its own microbial community dynamics.

The challenge of this work is to carry out the rheological characterization of concentrated suspensions of viscoplastic objects suspended in a viscoelastic matrix. Three structural constraints are faced: the heterogeneity of the particles, the size of particle in relation to the size of the whole system studied, and the proximity between the consistency of the suspending phase and that the consistency of the particles. In the food context, some biological constraints are added: small lifetimes of bolus, in vivo sampling and test conditions of temperature and humidity. All these constraints lead to a compromise in rheometry, at the edge of continuum mechanics, aiming to measure useful rheological properties. To carry out the rheological characterizations quickly and efficiently, two original devices has been designed trough this work. Applied to food bolus from cheese, rheology comes to govern flows in the mouth and induce the creation of exchange area in the mouth, during the chewing process. Through these interfaces, the savors and flavors are released and transported to the sensory receptors. The results show the relationship between the yield stress of the bolus and flavors release of different hydrophobic aromas, depending on the firmness and fat content of the cheeses. Specifically, fluid suspending matrix appears to play a major role in the creation and persistence of exchange area.Applied to gastric juice from bread, the issue is whether changes in carbohydrate content could impact the rheology of gastric juice, modify the kinetics of stomach flow rate, and decrease the glycemic excursion. The results show the effect of amylose addition on increasing the viscosity for long digestion time, when the rheology is no longer governed by the jamming effect of the particles made of water-swollen bread. However, amylose does not seem to have any impact on the kinetics of emptying, which reinforces that the stomach flow rate is regulated by the caloric charge contained in the meal.; L'enjeu des travaux contenus dans cette thèse est la caractérisation rhéologique de suspensions concentrées d'objets viscoplastiques suspendus dans une matrice viscoplastique. Trois contraintes physiques se présentent : l'hétérogénéité des objets, la taille des objets au regard de la taille du système étudié, et la proximité entre la consistance de la phase suspendante et celle des objets. Dans notre contexte alimentaire, il faut ajouter des contraintes d'ordre biologique : les faibles durées de vie des produits, les prélèvements in vivo et la conservation des conditions de températures et d'humidité. L'ensemble de ces contraintes aboutit à une rhéométrie spécifique, aux frontières de la mécanique des milieux continues, avec pour objectif de mesurer des propriétés rhéologiques pertinentes. Pour cela, deux instrumentations originales ont été construites pour effectuer la caractérisation rhéologique le plus vite et au plus près de la génération des échantillons.Appliquée aux bols alimentaires issus de fromage, leur rhéologie vient gouverner les écoulements en bouche et induire la création de surface d'échange en bouche, au travers de la mastication. Au travers de ces interfaces, les arômes et les sapides sont libérés et transportés vers les récepteurs sensoriels. Les résultats montrent le lien entre le seuil de contrainte à l'écoulement du bol et la libération d'arômes de différents hydrophobicités, fonction de la fermeté et du taux de matières grasses du fromage. Plus particulièrement, la phase suspendante fluide, semble jouer un rôle majeur dans la création et la persistance des surfaces d'échanges. Appliquée aux jus gastriques issus de pain, l'enjeu est de savoir si des modifications des contenus en glucides pouvaient impacter la rhéologie des jus gastriques, modifier les cinétiques de vidange en sortie d'estomac, et diminuer l'excursion glycémique. Les résultats montrent l'effet d'un ajout d'amylose sur l'augmentation de la viscosité aux temps de digestion longs, lorsque la rhéologie n'est plus gouvernée par l'encombrement des particules de pain gonflées d'eau. Cependant, l'amylose ne semble pas avoir d'impact sur les cinétiques de vidange, ce qui vient conforter que le débit en sortie d'estomac est régulé par la charge énergétique contenue dans le repas.

The challenge of this work is to carry out the rheological characterization of concentrated suspensions of viscoplastic objects suspended in a viscoelastic matrix. Three structural constraints are faced: the heterogeneity of the particles, the size of particle in relation to the size of the whole system studied, and the proximity between the consistency of the suspending phase and that the consistency of the particles. In the food context, some biological constraints are added: small lifetimes of bolus, in vivo sampling and test conditions of temperature and humidity. All these constraints lead to a compromise in rheometry, at the edge of continuum mechanics, aiming to measure useful rheological properties. To carry out the rheological characterizations quickly and efficiently, two original devices has been designed trough this work. Applied to food bolus from cheese, rheology comes to govern flows in the mouth and induce the creation of exchange area in the mouth, during the chewing process. Through these interfaces, the savors and flavors are released and transported to the sensory receptors. The results show the relationship between the yield stress of the bolus and flavors release of different hydrophobic aromas, depending on the firmness and fat content of the cheeses. Specifically, fluid suspending matrix appears to play a major role in the creation and persistence of exchange area.Applied to gastric juice from bread, the issue is whether changes in carbohydrate content could impact the rheology of gastric juice, modify the kinetics of stomach flow rate, and decrease the glycemic excursion. The results show the effect of amylose addition on increasing the viscosity for long digestion time, when the rheology is no longer governed by the jamming effect of the particles made of water-swollen bread. However, amylose does not seem to have any impact on the kinetics of emptying, which reinforces that the stomach flow rate is regulated by the caloric charge contained in the meal.; L'enjeu des travaux contenus dans cette thèse est la caractérisation rhéologique de suspensions concentrées d'objets viscoplastiques suspendus dans une matrice viscoplastique. Trois contraintes physiques se présentent : l'hétérogénéité des objets, la taille des objets au regard de la taille du système étudié, et la proximité entre la consistance de la phase suspendante et celle des objets. Dans notre contexte alimentaire, il faut ajouter des contraintes d'ordre biologique : les faibles durées de vie des produits, les prélèvements in vivo et la conservation des conditions de températures et d'humidité. L'ensemble de ces contraintes aboutit à une rhéométrie spécifique, aux frontières de la mécanique des milieux continues, avec pour objectif de mesurer des propriétés rhéologiques pertinentes. Pour cela, deux instrumentations originales ont été construites pour effectuer la caractérisation rhéologique le plus vite et au plus près de la génération des échantillons.Appliquée aux bols alimentaires issus de fromage, leur rhéologie vient gouverner les écoulements en bouche et induire la création de surface d'échange en bouche, au travers de la mastication. Au travers de ces interfaces, les arômes et les sapides sont libérés et transportés vers les récepteurs sensoriels. Les résultats montrent le lien entre le seuil de contrainte à l'écoulement du bol et la libération d'arômes de différents hydrophobicités, fonction de la fermeté et du taux de matières grasses du fromage. Plus particulièrement, la phase suspendante fluide, semble jouer un rôle majeur dans la création et la persistance des surfaces d'échanges. Appliquée aux jus gastriques issus de pain, l'enjeu est de savoir si des modifications des contenus en glucides pouvaient impacter la rhéologie des jus gastriques, modifier les cinétiques de vidange en sortie d'estomac, et diminuer l'excursion glycémique. Les résultats montrent l'effet d'un ajout d'amylose sur l'augmentation de la viscosité aux temps de digestion longs, lorsque la rhéologie n'est plus gouvernée par l'encombrement des particules de pain gonflées d'eau. Cependant, l'amylose ne semble pas avoir d'impact sur les cinétiques de vidange, ce qui vient conforter que le débit en sortie d'estomac est régulé par la charge énergétique contenue dans le repas.

Metabolomics approaches, particularly those based on mass spectrometry (MS) techniques,are being developed and appear as a must in the modern food science and microbiologyresearch to investigate food quality and safety. Cheese ripening mechanisms has always beeninvestigated with targeted approaches. Our objective was to assess the relevance ofuntargeted metabolomics to explore cheese ripening. MS metabolic fingerprints were foundto differ significantly depending on the incubation time, pointing out the capacity of thisapproach to study the evolution of bacterial metabolism within cheese. Forty-five metaboliteswere identified on the basis of an internal data bank. Variations over time of a large diversityof well-known cheese metabolites such as 12 amino acids and 25 volatile compounds, butalso less studied ones such as 4 vitamins and L-carnitine were highlighted. From now on,untargeted metabolomics offer new perspectives for the understanding of cheese ripeningmechanisms.

Microorganisms play an important role in the development of cheese flavour. Our aim was todevelop a methodological approach to facilitate the screening of various cheese-relatedbacteria for their ability to produce aroma compounds. We combined the use of a curd-basedmedium incubated under cheese conditions, the extraction of volatiles using headspace trapcoupled to gas chromatography-mass spectrometry, a powerful headspace method ofextraction of volatiles coupled to gas chromatography-mass spectrometry, and ametabolomics-based method of data processing. This approach was successfully applied to 20species, including lactic acid bacteria, surface bacteria and propionibacteria. Principalcomponent analysis of volatile profiles differentiated species on their ability to produce ethylesters, sulfur-containing compounds and branched-chain alcohols, branched-chain acids,diacetyl and related carbonyl compounds, among others. This approach can be applied toscreen the potential of strains from different origins in pure or mixed cultures.

Flow cytometry has been used as a routine method to count somatic cells in milk, and to ascertain udder health and milk quality. However, few studies investigate the viability of somatic cells and even fewer at a subpopulation level to follow up how the cells can resist to various stresses that can be encountered during technological processes. To address this issue, a flow cytometry approach was used to simultaneously identify cell types of bovine milk using cell-specific antibodies and to measure the cell viability among the identified subpopulations by using a live/dead cell viability kit. Confirmation of the cell viability was performed by using conventional microscopy. Different physico-chemical treatments were carried out on standardized cell samples, such as heat treatment, various centrifugation rates and storage in milk or in PBS pH 7.4 for three days. Cytometry gating strategy was developed by using blood cell samples stored at 4°C in PBS and milk cell samples heat-treated at 80°C for 30 min as a control for the maximum (95.9%) and minimum (0.7%) values of cell viability respectively. Cell viability in the initial samples was 39.5% for all cells and varied for each cell population from 26.7% for PMNs, to 32.6% for macrophages, and 58.3% for lymphocytes. Regarding the physico-chemical treatments applied, somatic cells did not sustain heat treatment at 60°C and 80°C in contrast to changes in centrifugation rates, for which only the higher level, i.e. 5000×g led to a cell viability decrease, down to 9.4%, but no significant changes within the cell subpopulation distribution were observed. Finally, the somatic cells were better preserved in milk after 72h storage, in particular PMNs, that maintained a viability of 34.0 ± 2.9% compared to 4.9±1.9% in PBS, while there was almost no changes for macrophages (41.7 ± 5.7% in milk vs 31.2 ± 2.4% in PBS) and lymphocytes (25.3 ± 3.0% in milk vs 11.4 ± 3.1% in PBS). This study provides a new array to better understand milk cell biology and to establish the relationship between the cell viability and the release of their endogenous enzymes in dairy matrix

New approaches, mainly based on mass spectrometry techniques, are being developed and appearas a must in the modern food science and microbiology research to investigate food quality andsafety. Their use allows progressing from classical methodologies to advanced analytical strategies toextend our understanding of the microbial metabolism involved in the final properties of fermentedfoods.Our objective was to push out the boundaries of these metabolomics approaches to explore theinfluence of a technological parameter, such as the spatial distribution of bacterial colonies, thoughtto generate fine differences in cheese metabolome.In cheese, bacteria grow as colonies of which spatial distribution is characterized by the size ofcolonies and the distance between them. Two different types of cheeses were generated basedon the variation of the spatial distribution, leading to cheeses containing the same populationof Lactococcus lactis , distributed either as big or small colonies. The peptidome, the soluble andvolatile metabolomes were investigated after 2, 13 and 27 days of ripening using gas and liquidchromatography - mass spectrometry. We demonstrated the capacity of those metabolomics approaches to reveal fine differences between the two cheese metabolomes with most of the fold-changes ranging from 1.2 to 1.8 between big or small colony cheeses. Some peptides, soluble and volatile metabolites were identified as markers of the spatial distribution parameter throughout the ripening. All techniques were complementary andled to a coherent view of the ripening mechanisms induced by the spatial distribution parameter.These results show the interest of metabolomics approaches to generate new insightson little-knownmetabolitesand to detect even slight quantitative differencesbetween two conditions.As perspectives,metabolomics approaches are relevant tools to deepen the knowledge aboutmechanisms responsible for cheese ripening and appear to be relevant to explore any otherfermentation or biological mechanisms in food

International audience; BackgroundPropionibacterium freudenreichii is a food grade bacterium consumed both in cheeses and in probiotic preparations. Its promising probiotic potential, relying largely on the active release of beneficial metabolites within the gut as well as the expression of key surface proteins involved in immunomodulation, deserves to be explored more deeply. Adaptation to the colon environment is requisite for the active release of propionibacterial beneficial metabolites and constitutes a bottleneck for metabolic activity in vivo. Mechanisms allowing P. freudenreichii to adapt to digestive stresses have been only studied in vitro so far. Our aim was therefore to study P. freudenreichii metabolic adaptation to intra-colonic conditions in situ.ResultsWe maintained a pure culture of the type strain P. freudenreichii CIRM BIA 1, contained in a dialysis bag, within the colon of vigilant piglets during 24 hours. A transcriptomic analysis compared gene expression to identify the metabolic pathways induced by this environment, versus control cultures maintained in spent culture medium.We observed drastic changes in the catabolism of sugars and amino-acids. Glycolysis, the Wood-Werkman cycle and the oxidative phosphorylation pathways were down-regulated but induction of specific carbohydrate catabolisms and alternative pathways were induced to produce NADH, NADPH, ATP and precursors (utilizing of propanediol, gluconate, lactate, purine and pyrimidine and amino-acids). Genes involved in stress response were down-regulated and genes specifically expressed during cell division were induced, suggesting that P. freudenreichii adapted its metabolism to the conditions encountered in the colon.ConclusionsThis study constitutes the first molecular demonstration of P. freudenreichii activity and physiological adaptation in vivo within the colon. Our data are likely specific to our pig microbiota composition but opens an avenue towards understanding probiotic action within the gut in further studies comparing bacterial adaptation to different microbiota.

Bacteria are immobilized in cheese after the coagulation step whatever the technology. They grow as bacterial colonies and are the main agents of cheese ripening. However, questions remain, on the microscopic scale, about how metabolic activities of the bacterial colonies affect (i) the surrounding micro-environment of the cheese matrix and (ii) the diffusion of molecules from the cheese matrix into the bacterial colonies. Our objective was then developing non-destructive approaches, to be able to explore different parameters of the micro-environment around colonies and the porosity of colonies on the spatio-temporal scale.We used a model cheese inoculated with a Lactococcus strain and coagulated in an examination chamber. This setup allowed monitoring the changes of fluorescence intensity of dyes specific of pH and redox potential, using confocal microscopy. We also assessed the porosity of bacterial colonies by monitoring the diffusion of fluorescent molecules of different types and sizes (dextrans and proteins) inside colonies.As a result, we succeeded in measuring in situ the pH and the redox state around bacterial colonies, demonstrating, respectively, the absence and the presence of micro-gradients. This setup also allowed observing differences of diffusion behaviors, inside the colonies throughout time, depending on the type and the size of the diffusing molecules. These non-destructive approaches led to new insights about the interactions between the bacterial colonies and the cheese matrix, by describing changes in the micro-environment around bacterial colonies in a solid fermented food. It could now be adapted to more heterogeneous and complex cheeses, or any other fermented foods.

Microorganisms play an important role in the development of cheese flavour, producing a variety ofaroma compounds for which lactose/citric acid, proteins and fat are precursors. There is a demandfrom cheese producers to diversify the flavour of semi-hard cheeses. A large screening is required toidentify strains of interest among the diversity of cheese-related bacterial species and strains. This stepcannot be bypassed and is time-consuming. Our aim was to develop a methodological approach tofacilitate and expedite the screening of various cheese-related bacteria for their ability to producearoma compounds. Our strategy was to combine: (i) the use of a curd-based broth medium incubatedunder conditions mimicking cheese manufacturing and ripening, ii) a powerful method of extraction ofvolatiles, headspace trap, coupled to gas chromatography-mass spectrometry, and iii) a metabolomicsbasedmethod of data processing using the XCMS package of R software and multivariate analysis.This approach was applied to eleven species: lactic acid bacteria (Leuconostoc lactis, Lactobacillussakei, Lb. paracasei, Lb. fermentum, and Lb. helveticus), surface bacteria (Brachybacterium articum,Brachybacterium tyrofermentans, Brevibacterium aurantiacum, Microbacterium gubbeenense),Propionibacterium freudenreichii and Hafnia alvei. All the strains grew, with maximal populationsranging from 7.4 to 9.2 log CFU/g. In total, 53 volatile compounds were identified, of which 50 variedsignificantly in abundance between bacteria. Principal component analysis of volatile profilesdifferentiated species on their ability to produce ethyl esters (associated with Brachybacterium), sulfurcompounds and branched-chain alcohols (H. alvei), branched-chain acids (H. alvei, P. freudenreichiiand Lb. paracasei), diacetyl and related carbonyl compounds (M. gubbeenense and Lb. paracasei),among others. The present approach was then successfully applied to screen collections of lactic andpropionic acid bacteria. The metabolomics-based method of data processing can be widely applied inthe field of food flavour chemistry.

Removal of somatic cells by the bacterial epuration without drastic changes on Swiss-type cheese quality. 17. Word Congress of Food Science & Technology (IUFoST)

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Cheese ripening mechanisms has always been investigated with targeted approaches. We assessed the relevance of untargeted metabolomics to study the influence of a ripening parameter, known to generate fine differences on bacterial metabolism within cheese. Metabolic fingerprints were acquired by LC(ESI+/-)-HRMS throughout 1 month of ripening, based on two different extractions. Data processing (XCMS) and data analysis highlighted significant differences in bacterial metabolome profiles. 27 metabolites were further identified thanks to an in-house database. From now on, untargeted metabolomics can be considered as a new approach for the understanding of cheese ripening mechanisms

National audience

Food products are complex matrices. They may contain molecules from several families, which interact with themselves to generate structure and functionality. Among these molecules are proteins and peptides which may originate from protein hydrolysis, e.g. in cheese. It is still difficult to establish the relationship between a pool of peptides and their technofunctionalities such as emulsifying, foaming, gelling or even viscoelastic properties in a food matrix. The information usually known is the hydrolysis degree which informs on the average size of the peptides formed. A high hydrolysis degree induces the production of a peptide pool of small size (less than 20 amino-acids). Advances in identification methods render possible the identification of peptides that are present in the food matrix. From the peptide sequence, the peptide physico-chemical characteristics such as size, charge, hydropathy, aliphatic index, isoelectric point could be calculated as well as their secondary structure. The aim of this study was to determine which physico-chemical and structural characteristics of peptides are involved in the stretchability of cheese. From a previous study [1] on a fermented food product (Swiss-type cheese) for which one typical functionality criterion was measured (stretchability) and peptides were identified, we developed a methodology based on multivariate exploratory analysis such as Principal Component Analysis and Correspondence Analysis to establish a relationship between peptide characteristics and their technofunctional property. This method allowed us to determine that peptides predominantly involved in the stretchability of the cheese were amphiphilic and contained more than 15 amino-acids. It will be then possible to target enzymes able to produce peptides with chosen characteristics. This method can be applied to other types of peptides and other food technofunctionalities in other food matrices.

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Theme 2: Feeding the future with sustainable agro-food systems. WS 2.2. Transition Issues in Production, Marketing and Consumption for the Agro- Ecological Development of Animal Production; International audience; Pastoralism has been discredited for a long time on the grounds that it would harm the agrarian activities. Today, it is generally acknowledged that pastoralism has positive qualities due to the grazing by herds of spontaneousresources., Pastoralism has become a matter of public interest because pastoral systems are low inputs, isenvironment-friendly and is associated to traditionh . However, the products from this type of breeding do nothave a real economic benefit of this turnaround. The paper analyses the possibilities to qualify the Corsicancheeses as "pastoral products," taken for an ideal-type, to understand how and to what extent the professionals ofthe market act to translate the pastoral features of insular cheeses. A survey conducted among producers and users of cheeses (restaurateurs, specialty retailers and prescribers) in the island and outside (Languedoc andProvence) asks: - what are the components of the corsican breeding (local breed, flock management and forageresources) taken for “pastoral features” and associated with insular cheeses? - what are the similarities and thedifferences of their market translations in Corsica and outside the island ? First, we present the distinctivecomponents of the insular pastoralism used by breeders and the actors surrounding production. Secondly, weconsider how the professionals of the market develop commercial arguments and describe cheeses locally andoutside the island. Then, practical ways of incorporating the conditions of production to the qualification operatedby the market are presented. Finally, to highlight the mode of existence of Corsican pastoral cheeses we proposeto define two ways of qualification that we name (i) associative logic in which market mediations connectproductive practices - pastoral features - with consumption practices and (ii) dissociative logic that disconnectproducts from their conditions of production.

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During cheese processing and ripening, bacteria develop as colonies. Substrates and metabolites must then diffuse either from or into the colonies. Exploring how the inner cells of the colony access the substrates or get rid of the products leads to study the permeability of bacterial colonies in cheese. Indeed, if diffusion limitation exists, the inner cells may be starved and may not be in the same physiological state than the outer cells of the colony. The question is the same for the diffusion of intracellular proteolytic enzymes released after bacterial lysis during ripening, which has never been studied in cheese. The objective of this study was to explore whether Lactococcus colonies in a model cheese were permeable to the diffusion of molecules. We varied size, shape and charge of diffusing molecules in order to explain how permeability was influenced. We used fluorescent-labelled molecules and time-lapse confocal microscopy examinations.We showed that colonies were permeable to flexible and neutral-charged dextrans whatever their size (from 4 to 155 kDa), but were not permeable to globular and charged milk proteins.We suspect the surface properties of bacterial cells (hydrophobicity and surface charges) to be of great importance on the permeability of the colony.

The industrial relevance of mass transport in dairy products is vast. While it is known that the microstructure of dairy matrices affects diffusion, the link between structure and diffusion has rarely been established and the properties of solutes were almost never considered. Our objective was to investigate the impact of the microstructure of different model cheeses on diffusion of solutes with different physicochemical characteristics. The diffusion of rigid and charged proteins versus flexible and charge - neutral dextrans of various sizes was studied in model cheeses obtained from ultra - or microfiltered milk. Diffusion coefficients were measured using the Fluorescence Recovery After Photobleaching technique. Structural parameters of the model cheeses we re quantified by low - temperature transmission electron microscopy coupled to image analysis. Solute diffusion was sensitive to the microstructure of the matrices, especially to the degree of aggregation of casein micelles, which depends on heat treatment a nd acidification level of the milk retentate. As expected, the diffusion greatly decreased as solute size increased but, more surprisingly, rigid and negatively charged solutes were much more hindered than the flexible and charge - neutral solutes. Besides t he obstruction effects generated by the matrix microstructure, the molecular interactions between the matrix and the solute could explain different diffusion behaviors

Camel milk is consumed as raw milk or after pasteurization. An other possible valorisation of camel milk is to transform it in cheese. In this work, white cheese from camel milk was manufactured and physico-chemically characterized. A same protocol was used to make the same cheese with cow milk previously standardized to have the same concentrations in fat (~20 g/kg) and total nitrogen (~25 g/kg) contents than those of camel milk. Milks and cheeses were characterized with special attentions paid on their rates of acidification (for milks) and for their mineralization and buffering capacity during chemical alkalinisation (for cheeses). Recoveries of protein and fat were also calculated for cheeses manufactured with both milks. The rates of acidification were very different for both milks because the final pHs were reached at 5 and 18h for cow and camel milks, respectively. The recovery of protein in the cheese was better for camel milk (~84%).than those determined for cow milk (~73%) although that the recovery of fat was better for cow milk than camel milk (~68 and ~57%’ respectively). On the other hand, cheeses manufactured with camel milk were more mineralized in calcium than those made with cow milk. Concerning the buffering capacity, maximal buffering capacities were determined at pH close to 6.0 for both cheeses. It was noted a second maximal peaks at pH 4.0 for cow milk but not for camel milk. All these results will be discussed in relation with our knowledge on cow milk and also by taking into account the special composition and organisation of camel milk.

Report on an American Academy of Microbiology Colloquium held in Washington, DC, in June 2014Edited by Jeffrey Fox; The American Academy of Microbiology (Academy) is the honorific branch of the American Society for Microbiology (ASM), a non-profit scientific society with nearly 40,000 members. Fellows of the Academy have been elected by their peers in recognition of their outstanding contributions to the field of microbiology.Through its colloquium program, the Academy draws on the expertise of these fellows to address critical issues in microbiology. FAQ reports are based on the deliberations of 15-20 expert scientists who gather for a day todevelop science-based answers to questions the public might have about topics in microbiology. The reports are reviewed by all participants, and every effort is made to ensure that the information is accurate and complete. The contents reflect the views of the participants and are not intended to reflect official positions of the Academy or ASM. The Academy thanks the efforts of previous staff, Leah Gibbons and Shannon Greene, Ph.D., for their assistance on this project, and of current staff, Chelsie Geyer, Ph.D., for her work on the final product.Contents of the report may be distributed further so long as the authorship of the Academy is acknowledged and this disclaimer is included.

Mozzarella, one of the most consumed cheeses in the world was traditionally done with cow milk. The use of camel milk was tried in the present study. AlI technological production chain is presented in this work. For clotting camel milk,Chy-Max MIOOO (Chr Hansen ® Denmark) was used. For lactic culture,mesophilic starters (Coquard, France) were used. On average, camel mozzarella yield was 7,05% and the glohal composition on fat, protein, lactose, ash, total solids was 18,78±J,58, 30,02±J,72, 0, 3,36±O,45, 53,79±2,34% respectively. Microbiological control showed absence of Salmonella, Lis/eria, S/aphylococcus in aIl studied cheeses. Glubally composition is c10sed ta buffalo or cow mozzarella, but the texture of camel mozzarella is quite differenl. Further studies are needed 10 describe rheological properties of carnet mozzarella.

National audience; L’Appellation d’Origine Contrôlée (AOC) est un des signes d’identification de la qualité et de l’origine géographique existant en France. Le nombre de produits AOC ou AOP (Appellation d’Origine Protégée ; appellation européenne) est en constante augmentation en France comme en Europe. Dans l’Union européenne, les pays les plus concernés par la certification AOC sont la France, l’Italie, la Grèce et l’Espagne. Les AOC, fortement implantées dans les secteurs viticole et fromager, sont également présentes dans d’autres secteurs agroalimentaires tels que la production d’huile et les produits d’origine animale ou végétale. Compte tenu du développement des labels AOC, il est intéressant d’analyser leur potentiel et leur efficacité à créer de la valeur dans les filières alimentaires notamment dans un contexte de diminution du nombre d’entreprises et d’exploitations. Nous synthétisons ici les résultats d’études empiriques portant sur l’utilisation du label AOC dans la filière laitière française. Notre analyse porte sur le label AOC dans le secteur fromager en France, secteur comprenant le plus grand nombre de produits sous AOC après le vin. Le fromage représente 10 % de la valeur des AOC en France et 91 % hors vin. Dans le secteur fromager, la part de l’AOC est de 25 % en valeur en France (15 % en volume) avec 45 fromages certifiés en 2013. La moitié des entreprises fromagères est engagée dans la démarche AOC pour lesquelles l’AOC représente 45 % de la production. Les résultats montrent que les consommateurs ont globalement un faible attachement au label AOC. Cependant l’AOC, qui est adoptée de façon volontaire par les entreprises, contribue au maintien sur le marché des entreprises fromagères de petite taille.

Erratum publié en novembre 2015, Volume 95, Issue 6, pp 919-920 - Clé UT 000364974900008 - http://link.springer.com/article/10.1007%2Fs13594-015-0221-x; Somatic cells are an important component naturally present in milk, and somatic cell count is used as an indicator of udder health and milk quality. The role of somatic cells in dairy processes and products is ill-defined in most studies because the role of these cells combines also the concomitance of physicochemical modifications of milk, bacterial count, and the udder inflammation in the presence of high somatic cell count. The aim of this review is to focus on the role of somatic cells themselves and of endogenous enzymes from somatic cells in milk, in dairy transformation processes, and in characteristics of final products overcoming biases due to other factors. The immune function of somatic cells in the udder defense and their protective role in milk will be primarily considered. Different characteristics of milk induced by various somatic cell counts, types, and their endogenous enzymes influencing directly the technological properties of milk and the final quality of dairy products will be discussed as well. By comparing methods used in other studies and eliminating biases due to other factors not considered in these studies, a new approach has been suggested to evaluate the effective role of somatic cells on dairy processes and products. In addition, this new approach allows the characterization of somatic cells and their endogenous enzymes and, in future research, will allow the clarification of mechanisms involved in the release of these components from somatic cells during dairy processes, particularly in cheese technologies.

International audience

International audience

Today, wooden shelves are used for the ripening of about 500,000 tons of cheese per year in Europe, including about 350,000 tons in France, such as most of the famous cheeses with the protected designation of origin (PDO), e.g., Comté, Reblochon, Beaufort, Munster, Cantal, and Roquefort. For some PDO cheeses, the use of wooden tools is mandatory.Many cheesemakers believe that wooden tools improve the organoleptic and typical characteristics of their final products. Wood is a natural and sustainable material which has been used for centuries in traditional cheese production in a wide variety of forms (vats, shelves, and packaging). Wood is important in the cheesemaking process, interacting with the milk in vats or with the cheeses placed on shelves for ripening. Wood is viable due to its ability to exchange water but, above all, because it is covered by a rich microbial biofilm. As wood is porous and difficult to clean, the European Commission regularly highlights the question of its safety when in contact with food and calls for deeper scientific investigation. In this review, knowledge about the multiple technological roles of wood in dairy technology is discussed. The crucial role of wood as a reservoir of microbialbiodiversity for traditional cheeses is reviewed, along with results of safety assessments. As a conclusion, the numerous questions remaining about this natural inoculating system are discussed.

Introduction and objective: Unbalanced diet with an overconsumption of salt contributes to the development of cardiovascular disease. Several strategies are currently investigated to design low-salt food while maintaining taste and consumer liking. The strategy relying on cross-modal sensory compensation is being tested within the framework of the EU-TeRiFiQ research project. In this context, this study had for aim to examine whether selected aromas could help to maintain salt and fat perception in low-salt real cheese. Methods: Two commercial cheeses, low-salt cheese (LSC) and regular-salt cheese (RSC), were reprocessed by grinding and addition of a sardine aroma associated to salty taste (LSC sardine), a butter aroma associated to fat perception (LSC butter), a blended aroma (sardine + butter, LSC blended) and non-flavoured (LSC-u and RSC-u). A total of 9 samples, which include graded and non-graded LSC and RSC were prepared. Fifty nine consumers were asked to rate taste, texture, and aroma attributes for each sample in two conditions: with and without noseclip; in the noseclip condition, participants were not able to perceive the aroma. Results: The samples were characterized by means of rheological measurements. The results indicated only a low impact of aroma addition on products’ structure (p=0.045), which allowed for the direct comparison of flavored and unflavored samples on the sensory attributes. Cheese grading affected sensory texture and taste of LSC and RSC (p

Cheese from camel milk was never produced by traditional way. However, Hansen© (Denmark) delivered recently new coagulant agent named "Chy-Max M" containing transgenic camel chymosine. In the present study, impact of calcium, lactation stage and curd acidification were investigated. Camel milk was shared into 6 samples (100g each) submitted to 3 types of treatment (1. calcium chloride solution (500 g/L diluted 1/10 water); 2. powder of calcium phosphate; 3. no calcium) and 2 temperatures (20°C/36°C). Rennet 50 ?L/L (Chy- Max) was added in all samples. Milk coagulation was faster at 36°C and renneting pH lower. No difference in clotting time and curd firmness after calcium addition was observed. The curd firmness at 36°C was stronger than at 20°C. For measuring impact of lactation stage, coagulation capacity and curd yield on milk was tested in milk provided by one camel from 12th to 25th day postpartum. Milk was coagulated by Chy-Max (50 ?L/L/20°C). No coagulation was observed in the first days of experiment. Then curd start to be formed, but with low yield. The curd was correct and ready to use for cheese making only from the 20th day post-partum. Acidification of camel cheese curd without starters was measured at 20°C and 36°C during 10 hours. Milk pH and curd pH were measured during all cheese processing. At the beginning, milk pH was 6.38 whatever the temperature. Acidification was faster at 36°C than at 20°C. At the time of coagulation, pH of 20°C curd was 5.80 vs 5.08 at 36°C.

Usually, camel milk is consumed as raw milk, after pasteurization or like fermented beverages (Shubat in Kazakhstan or Chal in Turkmenistan for exemple). An other possible valorisation of camel milk is to transform it in cheese, but the cheese yield was low due to a bad coagulation with traditional bovine coagulant. Recently, it was showed that it was possible to make cheese with camel chymosin (ChyMaxM from Hansen, Denmark). In this work, white cheeses were made with camel and cow milks with the same procedure. Milks and cheeses were characterized with special attentions paid on the compositions and rates of acidification of milks, and on the compositions and buffering capacities of cheeses. Recoveries of protein, fat, calcium and dry matter in cheeses were also calculated.