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L’INRAE d’Aurillac mène des recherches sur la microbiologie et la technologie des fromages du Massif Central avec pour objectifs la compréhension des processus de fabrication et d’affinage des fromages et la recherche de solutions microbiennes et technologiques pour l’amélioration de leurs qualités. Leurs recherches ont ainsi contribué au maintien des prairies naturelles du Massif Central, au développement de l’activité économique, la création d’emplois et la reconnaissance internationale des fromages au lait cru. Cette étude a été conduite selon la méthode ASIRPA ex-post.; The INRAE of Aurillac carries out research on the microbiology and technology of cheeses from the Massif Central with the aim of understanding the manufacturing and ripening processes of cheeses and the search for microbial and technological solutions to improve their qualities. Their research has thus contributed to the maintenance of the natural meadows of the Massif Central, the development of economic activity, the creation of jobs and the international recognition of raw milk cheeses. Cette étude a été conduite selon la méthode ASIRPA ex-post.

Les produits laitiers, et le fromage en particulier, font partie de notre alimentation et de notre culture. Ce passé fromager reste pourtant largement méconnu. Aujourd’hui, la France, qui se considère comme le « pays du fromage », ne connaît rien ou presque de son Antiquité fromagère, négligeant les tessons de faisselle trouvés en nombre dans les villae et les villes gallo-romaines. Alain Ferdière entreprend ici une brève et accessible synthèse centrée sur les provinces gauloises et couvrant l’Antiquité au sens large, du Néolithique jusqu’au VIIIe siècle apr. J.-C., autour de la Méditerranée. S’appuyant sur les découvertes archéologiques et les sources anciennes, il fait le point de nos connaissances sur les vaches, brebis et chèvres qui fournissaient le lait nécessaire, mais aussi sur les manières de faire, les équipements et les outils. Le tableau ici esquissé pose un premier jalon dans un domaine de recherche qui, grâce aux avancées scientifiques en biochimie et paléogénétique, sera probablement bouleversé dans les années à venir.

With the ageing of the population worldwide, the increased prevalence of age-related neurodegenerative diseases is obvious and the prevention of cognitive decline, dementia and its main etiology, Alzheimer's disease (AD), constitutes a current public health challenge. In this field, the role of diet has been widely investigated, mainly late-life, and the strategy of increased adherence to heathy dietary patterns as preventive lifestyle is well documented and credible. Among all, some food groups are yet less studied, and still debated as relevant components of an efficient strategy. This is the case for dairy products (DPs), whose benefits for cognitive functions are still questionable: results of epidemiological studies focusing on this food group are indeed heterogeneous to date. DPs are yet rich in essential nutrients (bioactive peptides, calcium, B vitamins, etc.) identified as potential preventive factors for brain aging. Higher DPs intakes have also been associated with benefits on chronic metabolic diseases, such as hypertension, type 2 diabetes or cardiovascular diseases, known as risk factors for dementia. Overall, a higher consumption of DPs could be, directly or not, associated with a slower cognitive decline and a reduced risk of dementia. This underlying hypothesis was the main of the present thesis, which aimed to estimate the role of DPs on the brain health among a population-based cohort of older adults, the Three-City cohort. Therefore, the aim was to i) precisely describe the sample of DPs consumers, as a whole (total DPs) and as DPs sub-types (i.e. milk, fresh-DPs and cheese), regarding socio-demographic and dietary characteristics; ii) to estimate the association of higher DPs (total and sub-types) exposures on the cognitive decline and the risk for dementia; iii) to estimate the association of higher DPs (total and sub-types) exposures on neuroimaging biomarkers of brain aging, considered as objective markers of early brain lesions, prior to clinical symptoms. First, we have highlighted three lifestyle and dietary patterns that are specific to each of the DP subtype consumers. Beyond the interest in total DPs, this result encouraged the individual consideration of milk, fresh DPs and cheese, for the next steps. Second, we reported a lack of association between the frequency of consumption of DPs as a whole, or as DPs sub-types and the slope of cognitive decline over time. On the other hand, higher frequencies of consumption of total DPs (≥4 times per day), or fresh DPs (≥0.5 times per day), (but not milk or cheese), were associated with a higher risk of developing dementia or Alzheimer's disease, compared with the lowest frequencies of consumption, over a 15-year follow-up period. To note, this last result was restricted to the male sub-sample. Finally, these unexpected results were in agreement with our last analysis focusing on brain imaging data. Thus, individuals (men and women as a whole) with the highest frequency consumption of fresh DPs (>1.5 times per day) significantly exhibited a smaller gray matter volume in the medial temporal lobe, 9 years after the dietary survey, and compared with those reporting the lowest frequency consumption of fresh DPs (, Alors que le vieillissement de la population mondiale est en perpétuel accroissement, l’émergence de maladies neurodégénératives liées au vieillissement cérébral pathologique, amène à faire de la prévention du déclin cognitif et de la démence (et son étiologie principale, la maladie d’Alzheimer), une priorité de santé publique. Dans ce contexte, le rôle de l’alimentation, à laquelle nous sommes exposés tout au long de la vie, a été largement investigué et représente une stratégie crédible de prévention. Pourtant, dans des profils alimentaires sains associés favorablement aux fonctions cognitives, la place des produits laitiers pose encore question : les résultats d’études épidémiologiques focalisant sur ce groupe alimentaire sont en effet hétérogènes. Source d’un ensemble de nutriments essentiels (peptides bioactifs, calcium, vitamines B, …) identifiés comme de potentiels facteurs préventifs du vieillissement pathologique, et associé à des effets bénéfiques sur les maladies chroniques métaboliques telles que l’hypertension, le diabète de type 2 ou les maladies cardiovasculaires, également connues comme des facteurs de risque de démence, une plus forte consommation de produits laitiers pourrait être associée, directement ou indirectement, à une diminution du risque de développer un déclin cognitif et une démence. C’est l’hypothèse sous-tendue par cette thèse d’épidémiologie qui avait pour but d’analyser les effets des produits laitiers sur la santé cérébrale de personnes âgées issues de la population générale et participantes de la cohorte Troiscités Bordeaux. La première partie descriptive de ce travail avait pour but d’appréhender les caractéristiques sociodémographiques et cliniques, et les apports alimentaires et nutritionnels des consommateurs de produits laitiers et de ses trois sous-types (le lait, les produits laitiers frais, le fromage). Nous avons mis en évidence trois profils de consommation et de mode de vie très spécifiques à chacun des sous-types de produits laitiers étudiés. Au-delà de l’intérêt pour les produits laitiers totaux, ce résultat a encouragé la considération individuelle du lait, des produits laitiers frais, du fromage, pour la suite du travail. Dans la seconde partie analytique, nous nous sommes intéressés à la relation entre les consommations de produits laitiers et l’évolution des performances cognitives, jusqu’à l’incidence de la démence et de la maladie d’Alzheimer. Aucune association n’était observée entre les produits laitiers quels qu’ils soient et le déclin cognitif. En revanche, de plus fortes fréquences de consommation de produits laitiers totaux (≥4 fois par jour), ou de produits laitiers frais (≥0,5 fois par jour), étaient associées à un risque plus élevé de développer une démence ou une maladie d’Alzheimer, par rapport aux fréquences de consommation les plus faibles, au cours de 15 ans de suivi. Ce résultat était spécifique aux hommes ; aucune association n’étant observée en population féminine. Enfin, ces résultats surprenants étaient en accord avec une analyse supplémentaire qui a porté sur des données d’imagerie cérébrale, marqueurs objectivables de lésions précoces, en amont des symptômes cliniques. Ainsi, les individus ayant la fréquence de consommation de produits laitiers frais la plus élevée (>1,5 fois par jour) présentaient un plus petit volume de matière grise dans le lobe temporal médian, 9 ans après l’enquête alimentaire, par rapport à ceux déclarant une fréquence de consommation faible (

Annexe documentaire numérique de Ferdière A., Séguier J.-M. 2020 : « Le fromage en Gaule à l’âge du Fer et à l’époque romaine : état des lieux pour sa production et analyse de sa place dans le monde antique », Gallia, 77-2, p. 157-229.

Le fromage est un produit omniprésent dans les sociétés anciennes, mais discret et laissant peu de traces de sa production, notamment pour ses témoignages matériels susceptibles d’être perçus par les archéologues : c’est pourquoi le sujet reste assez largement méconnu. Pourtant, plus généralement, les produits laitiers sont une part essentielle de l’alimentation dans les sociétés anciennes, notamment dans le monde méditerranéen et en Europe. Ces produits dérivés apparaissent donc vraisemblablement dès les prémices de la domestication des bovins, ovins et caprins, c’est-à-dire au Néolithique.

Annexe documentaire numérique de Ferdière A., Séguier J.-M. 2020 : « Le fromage en Gaule à l’âge du Fer et à l’époque romaine : état des lieux pour sa production et analyse de sa place dans le monde antique », Gallia, 77-2, p. 157-229.

International audience; Along with other dairy products cheese is an essential part of the diet of all pre-industrial societies. An outline of dairy technology is given followed by a more detailed examination of the documentation that was based mainly on archaeological data regarding the Roman provinces of Gaul, Germania and the Alps during the Iron Age and the Roman period. The main focus of this examination was on the operational sequence of cheese-making. The data collected for these provinces were then compared with textual, epigraphic and iconographic data for the rest of the ancient Greco-Roman world. Gaul’s place in this overview can be considered as highly informative, revealing –through the discovery of pottery cheese strainers– previously unsuspected production regions as well as gaps, which we try to explain.; El queso es, entre los productos lácteos, un elemento esencial de la alimentación en todas las sociedades preindustriales. Tras un repaso de la tecnología láctea, se examina en detalle la documentación – esencialmente arqueológica – relativa a las Galias, Germanias y provincias alpinas, para la Edad del Hierro y la época romana, basándose principalmente en la cadena operativa de la producción de queso. Luego, los datos adquiridos para estas provincias se ponen en perspectiva con todo el mundo antiguo, griego y romano, esta vez a través de datos principalmente textuales, epigráficos e iconográficos. La posición de la Galia en este cuadro puede así considerarse muy honorable, revelando – a través de las encellas de terracota – regiones productoras antes desconocidas, pero también lagunas que se intenta explicar.; Le fromage est, parmi les produits laitiers, un élément essentiel de l’alimentation dans toutes les sociétés préindustrielles. Après un rappel de la technologie laitière, la documentation – essentiellement archéologique – concernant les Gaules, Germanies et provinces Alpines est examinée en détail, pour l’âge du Fer et la période romaine, en se fondant largement sur la chaîne opératoire de la production de fromage. Puis les données acquises pour ces provinces sont mises en perspective avec l’ensemble du monde antique, grec et romain, cette fois à travers des données surtout textuelles, épigraphiques et iconographiques. La place de la Gaule dans ce tableau peut ainsi être considérée comme fort honorable, révélant – par les faisselles en terre cuite – des régions productrices auparavant insoupçonnées mais aussi des vides, que l’on tente d’expliquer.; Il formaggio è, tra i latticini, un elemento essenziale dell’alimentazione in tutte le società preindustriali. Dopo un riepilogo sulla tecnologia casearia, si esamina in dettaglio la documentazione – essenzialmente archeologica – relativa alle Gallie, le Germanie e province alpine, per l’età del Ferro e il periodo romano, basandosi in gran parte sulla catena operativa della produzione di formaggio. I dati acquisiti per queste province sono poi messi in prospettiva con tutto il mondo antico, greco e romano, questa volta attraverso dati prevalentemente testuali, epigrafici e iconografici. Il posto della Gallia in questa panoramica può quindi essere considerato molto onorabile, rivelando – attraverso le fiscelle di terracotta – regioni produttrici precedentemente sconosciute, ma anche lacune che si tentano di spiegare.

Dictionnaire de la Méditerranée, sous la direction de Dionigi Albera, Maryline Crivello et Mohamed Tozy, en collaboration avec Gisèle Seimandi, Actes Sud, 2016, 1694 p., ISBN 978-2-330-06466-2., Imprimés, Dicomed-073, DicoMed : Dictionnaire de la Méditerranée

New sequencing technologies allowed the development of methods such as metabarcoding. They use 16S rRNA, the ubiquitous gene of the bacteria domain, as a biomarker to study bacterial communities from samples of complex environments. The bioinformatic pipelines used to handle this type of data are well known but the taxonomic assignment is still a critical point. Misannotations are caused by short size sequences and high identity between bacterial species. Indeed, current technologies only allow to sequence two hyper-variable regions among the nine which compose the 16S rRNA. The available generalist databases (Greengenes, SILVA) do not reach enough accuracy to assign to the species rank. It is needed to create a curated reference database dedicated to the studied environment. Here we introduce the DAIRYdb, a manually curated database composed of full length 16S rRNA sequences from samples of dairy products and close environments (cheese, milk, teat surface, starter, whey). The DAIRYdb was constructed using the 16S rRNA sequences deposited in EMBL and NCBI. After bioinformatic treatments, automatic and manual curative steps, DAIRYdb is finally composed of 10290 complete 16S sequences. It shows a higher assignment accuracy compared to other databases, at all taxonomic ranks and with any assignment tool tested. Depending on the variable region used, up to 90% of the tested sequences are reassigned to the species level with DAIRYdb. DAIRYdb significantly improves taxonomic assignment accuracy for dairy environmental microbiome studies. It is available on public a repository (https://forgemia.inra.fr/umrf/dairydb).

Background Reads assignment to taxonomic units is a key step in microbiome analysis pipelines. To date, accurate taxonomy annotation of 16S reads, particularly at species rank, is still challenging due to the short size of read sequences and differently curated classification databases. The close phylogenetic relationship between species encountered in dairy products, however, makes it crucial to annotate species accurately to achieve sufficient phylogenetic resolution for further downstream ecological studies or for food diagnostics. Curated databases dedicated to the environment of interest are expected to improve the accuracy and resolution of taxonomy annotation. Results We provide a manually curated database composed of 10’290 full-length 16S rRNA gene sequences from prokaryotes tailored for dairy products analysis (https://github.com/marcomeola/DAIRYdb). The performance of the DAIRYdb was compared with the universal databases Silva, LTP, RDP and Greengenes. The DAIRYdb significantly outperformed all other databases independently of the classification algorithm by enabling higher accurate taxonomy annotation down to the species rank. The DAIRYdb accurately annotates over 90% of the sequences of either single or paired hypervariable regions automatically. The manually curated DAIRYdb strongly improves taxonomic annotation accuracy for microbiome studies in dairy environments. The DAIRYdb is a practical solution that enables automatization of this key step, thus facilitating the routine application of NGS microbiome analyses for microbial ecology studies and diagnostics in dairy products. Electronic supplementary material The online version of this article (10.1186/s12864-019-5914-8) contains supplementary material, which is available to authorized users.

Interview - durée : 06:54; National audience; C'est grâce à la présence de « lipides polaires » que le fromage, la crème et le lait pourraient réduire le taux sanguin de mauvais cholestérol. Alors que les mises en garde contre les produits laitiers sont légion, des travaux français publiés mercredi 12 juin dans la revue Gut ont de quoi surprendre : ils suggèrent que la consommation – à des doses raisonnables évidemment - de yaourts et de fromages, ainsi que de crème et de lait entier pourrait réduire le risque de maladie cardiovasculaire. De quoi changer le regard sur les laitages dans le « pays des 300 fromages ».

Milk is often subjected to technological treatments which have impacts on the structure of milk constituents and the characteristics of rennet curds. In this paper, the influence of the dairy fat structure on the biochemical and textural characteristics of curds coagulated by an extract of Calotropis procera leaves was studied. Standardized milks were reconstituted with the same contents in protein (35 g·kg− 1) and fat (35 g·kg− 1) but with different structures of fat i.e. homogenized anhydrous milk fat (HAMF), homogenized cream (HC) and non-homogenized cream (NHC). As expected, the size distributions of fat globules in the different milks were different. After their coagulations by the plant extract, the physico-chemical characteristics of the curds and respective wheys were determined. No difference was observed in the coagulation time between the three milks but the whey removed more quickly from HAMF and HC curds than NHC-curd. The biochemical analyses of curds revealed a lower content in dry matter and fat in the NHC-curd compared to HAMF- and HC-curds. Otherwise, the NHC-whey exhibited the highest amount of fat. Observations by confocal microscopy showed that the fat globules were homogenously distributed and well trapped in the protein networks of HAMF- and HC-curds. In the NHC-curd, the fat globules were located in whey pockets, with less connectivity with the protein network. The textural analysis showed that the NHC-curd was more elastic, soft and adhesive than HAMF- and HC-curds. Homogenization significantly reduced the loss of fat during cheese manufacturing and conferred specific textural characteristics to the curds coagulated by an extract of Calotropis procera.

International audience; Quaternary ammonium compounds (QACs) are both cationic surfactants and biocidal substances widely used as disinfectants in the food industry. A sensitive and reliable method for the analysis of benzalkonium chlorides (BACs) and dialkyldimethylammonium chlorides (DDACs) has been developed that enables the simultaneous quantitative determination of ten quaternary ammonium residues in dairy products below the provisional maximum residue level (MRL), set at 0.1mgkg(-1). To the best of our knowledge, this method could be the one applicable to milk and to three major processed milk products selected, namely processed or hard pressed cheeses, and whole milk powder. The method comprises solvent extraction using a mixture of acetonitrile and ethyl acetate, without any further clean-up. Analyses were performed by liquid chromatography coupled with electrospray tandem mass spectrometry detection (LC-ESI-MS/MS) operating in positive mode. A C18 analytical column was used for chromatographic separation, with a mobile phase composed of acetonitrile and water both containing 0.3% formic acid; and methanol in the gradient mode. Five deuterated internal standards were added to obtain the most accurate quantification. Extraction recoveries were satisfactory and no matrix effects were observed. The method was validated using the total error approach in accordance with the NF V03-110 standard in order to characterize the trueness, repeatability, intermediate precision and analytical limits within the range of 5-150mugkg(-1) for all matrices. These performance criteria, calculated by e.noval((R)) 3.0 software, were satisfactory and in full accordance with the proposed provisional MRL and with the recommendations in the European Union SANTE/11945/2015 regulatory guidelines. The limit of detection (LOD) was low (

In Press; The milking of Salers cows requires the presence of the calf. The removal of the calf would simplify the milking routine, but it could also modify the milk yield and the milk and cheese composition. Therefore, the aim of this experiment was to evaluate the effect of calf presence during milking during sampling period (winter or grazing periods), on dairy performance, milk fatty acid (FA) composition, lipolysis and cheese yield and composition. Nine and 8 Salers lactating cows were milked in the presence (CP) or absence (CA) of their calves respectively. During winter, the cows were fed a hay-based diet and then they only grazed a grassland pasture. Calf presence during milking increased milk yield and milk 16:0 concentration and decreased milk fat content and milk total odd- and branched-chain FA (OBCFA) concentrations. Calf presence only increased initial lipolysis in milk collected during the winter season. Milk from CP cows compared to CA cows resulted in a lower cheese yield and ripened cheeses with lower fat content. Milk from the grazing season had lower saturated medium-chain FA and OBCFA concentrations and higher 18:0, cis-9-18:1, trans-11-18:1 and cis-9, trans-11-CLA concentrations than that from the winter season. Initial milk lipolysis was higher in the winter than in the grazing season. These variations could be due to seasonal changes in the basal diet. Furthermore, the effect of calf presence during milking on milk fat composition was lower than that on dairy performance, cheese yield and composition. Removing the calf during the milking of Salers cows seems feasible without a decrease in milked milk, and with a positive effect on cheese yield and fat content, under the condition that we are able to select cows having the capacity to be milked easily without the calf.

Suivi et intérêt de la mesure du potentiel d'oxydo-réduction en transformation laitière

Bioactive peptides represent an interesting alternative to pharmaceutical drugs without known side effects, as they are present in a variety of protein-rich foods that are consumed on a daily basis. Most of these peptides are embedded and inactive in their parental protein and must be cleaved during food-processing, bacterial fermentation, or gastrointestinal digestion. In recent years, bioactive peptides have attracted increasing interest in the research community, and many health-promoting effects have been attributed to specific amino acid sequences. This mini-review provides a summary of the most important biological functions that have been described for bioactive peptides in various review papers, and an update on findings from the last two years for specific milk- and cheese-derived bioactive peptides.

National audience

The Oxford Companion to Cheese (10.1093/acref/9780199330881.001.0001); Mont d'Or

The Oxford Companion to Cheese (10.1093/acref/9780199330881.001.0001); Reblochon

The Oxford Companion to Cheese (10.1093/acref/9780199330881.001.0001); Abondance

Live Saccharomyces cerevisiae yeast strains are widely used as feed additives for dairy cow s. Although, perfectly safe and applied in several food processes, the potential contamination of milk by the strain and more generally its possible influence on the microbial profile of milk could be questioned, this concerns particularly traditi onal cheeses made with raw milk. In an attempt to address these questions, two experiments were performed: A trial in an experimental farm , where two groups of cows, one receiving yeast supplementation and the other one being an unsupplemented control, were compared and a field trial where herds received alternatively yeast-supplemented and control diets. In both cases, viable counts of different microbial groups, including yeasts and molds in general and S. cerevisiae in particular were analysed in tank milk and results from suppleme nted groups or periods were compared with control ones. No v iable S. cerevisiae were detected in any of the samples analysed. Moreover, no n oticeable differences in the microbial profiles were observed. This applies also to the evolution of the microbial composition during an experimental cheese processing trial. These data sug gest that live yeast additive distributed to dairy cows does not influence milk microbial composition and cheese-making abilities.

The Oxford Companion to Cheese (10.1093/acref/9780199330881.001.0001); Beaufort

Lactococcus lactis is used extensively for the production of various cheeses. At every stage of cheese fabrication, L. lactis has to face several stress-generating conditions that result from its own modification of the environment as well as externally imposed conditions. We present here the first in situ global gene expression profile of L. lactis in cheeses made from milk concentrated by ultrafiltration (UF-cheeses), a key economical cheese model. The transcriptomic response of L. lactis was analyzed directly in a cheese matrix, starting from as early as 2 h and continuing for 7 days. The growth of L. lactis stopped after 24 h, but metabolic activity was maintained for 7 days. Conservation of its viability relied on an efficient proteolytic activity measured by an increasing, quantified number of free amino acids in the absence of cell lysis. Extensive downregulation of genes under CodY repression was found at day 7. L. lactis developed multiple strategies of adaptation to stressful modifications of the cheese matrix. In particular, expression of genes involved in acidic- and oxidative-stress responses was induced. L. lactis underwent unexpected carbon limitation characterized by an upregulation of genes involved in carbon starvation, principally due to the release of the CcpA control. We report for the first time that in spite of only moderately stressful conditions, lactococci phage is repressed under UF-cheese conditions.

– Cantal is the third French Protected Denomination of Origin cheese. The Cantal cheesemaking process is similar to Cheddar cheese. Both processes involve a milling and a dry salting step which results in a homogeneous salted curd. In order to determine the key parameters of the manufacturing process acting on the specific characteristics of this cheese variety, an extensive and kinetic study repeated three times was carried out at nine stages from the raw milk to 120 d ripened cheese. The microbial ecosystem was explored by numeration and by direct extraction of DNA and PCR-Temporal Temperature Gradient Electrophoresis. Lysis of the lactic acid bacteria was checked by quantification of the intracellular lactate dehydrogenase activity. Carbon sources changes, solubilisation of minerals, proteolysis, lipolysis, and formation of neutral volatile compounds were also assessed. Cheese microstructure modifications and bacterial localisation were determined by confocal scanning laser microscopy. The controlled manufacturing conditions and the use of a complex mixture of starters led to very similar ripened cheeses. The compositional attributes (in particular total solids, fat, nitrogen forms), the lipolysis (0.7 ± 0.2% fat) and proteolysis final extent (34.4 g·kg–1 free amino acids in juice) were similar as well as major neutral volatiles compounds (2-butanone, ethanol and 2-butanol). Nevertheless, lactose and citrate metabolisms differed between the three trials and some free amino acids (Arg, Pro, Ser, Cit, Homocys) concentrations varied drastically during the ripening time course. CLSM micrographs showed that fat globules were disrupted during pressing and bacteria were preferentially localised at the fat/protein interface. As the lactic starter species were the same in the three trials and predominant during the cheese manufacture, the observed differences could result of one or several of the followings: (i) the raw milk microflora which showed to be different leading to growth or metabolism activity of particular subdominant populations during the process and the ripening; (ii) the more or less early lysis of the lactic starters; (iii) the possible interactions between raw milk microflora and the added starters. This extensive characterization of Cantal cheese provides a strong basis for building a rational concept of the key steps in which either technological actions or complementary microbial inoculation could be done in order to limit day to day variations.; Le fromage de Cantal est, en tonnage, la 3ème Appellation d'Origine Contrôlée française. Son procédé de fabrication, similaire à celui du Cheddar, implique une étape de broyage et salage à sec, qui résulte en un caillé salé homogène. Afin de déterminer les paramètres clé du procédé de fabrication agissant sur les caractéristiques spécifiques de cette variété de fromage, une étude approfondie et cinétique avec trois répétitions a été menée à 9 stades, du lait cru au fromage affiné 120 jours. L'écosystème microbien a été exploré par énumération et par extraction directe de l'ADN et PCR-Temporal Temperature Gradient Electrophoresis. La lyse des bactéries lactiques a été appréhendée par mesure de l'activité de la lactate déshydrogénase intracellulaire. Les changements intervenant dans les sources carbonées, la solubilisation des minéraux, la protéolyse, la lipolyse et l'apparition des composés volatiles neutres ont aussi été évalués. Les modifications de la microstructure du fromage ainsi que la localisation des bactéries ont été déterminées pas microscopie confocale à balayage laser (CLSM). La mise en oeuvre de conditions de fabrication très contrôlées et l'utilisation d'un levain complexe a conduit à des fromages affinés très similaires, tant sur le plan de la composition (en particulier l'extrait sec total, la matière grasse, les formes azotées) des niveaux de lipolyse (0.7 ± 0.2 % de la matière grasse) et de protéolyse (34,4 g·kg-1 d'acides aminés libres dans le jus) que sur le plan des teneurs en composés volatiles majoritaires (2-butanone, éthanol et 2-butanol). Néanmoins, les métabolismes du lactose et du citrate différaient entre les trois essais, ainsi que les concentrations en certains acides aminés libres (Arg, Pro, Ser, Cit, Homocys) qui variaient fortement au cours de l'affinage. Les photographies obtenues par CLSM montraient que les globules gras étaient brisés lors du pressage et que les bactéries étaient préférentiellement localisées à l'interface matière grasse/protéine. Comme le levain utilisé comportaient les mêmes espèces pour les trois essais et que celles-ci s'avéraient dominantes au cours de la fabrication, les différences observées peuvent résulter : (i) des variations observées dans la flore indigène du lait cru conduisant à la croissance ou l'activité métabolique de populations sous-dominantes particulières pendant la fabrication ou l'affinage ; (ii) de la lyse plus ou moins précoce des espèces du levain ; (iii) des interactions possibles entre la flore indigène du lait cru et le levain ajouté. Cette caractérisation approfondie du fromage Cantal offre une base solide pour construire un concept rationnel des étapes-clé au cours desquelles soit des actions technologiques, soit une inoculation microbienne complémentaire peuvent être réalisées afin de limiter les variations journalières et d'optimiser la qualité globale.

La microbiologie du lait et de sa transformation

International audience; Inflammation is a major biological process regulating the interaction between organisms and the environment, including the diet. Because of the increase in chronic inflammatory diseases, and in light of the immune-regulatory properties of breastfeeding, the ability of dairy products to modulate inflammatory processes in humans is an important but unresolved issue. Here, we report a systematic review of 52 clinical trials investigating inflammatory markers in relation to the consumption of dairy products. An inflammatory score (IS) was defined to quantitatively evaluate this interaction. The IS was significantly positive for the entire data set, indicating an anti-inflammatory activity in humans. When the subjects were stratified according to their health status, the IS was strongly indicative of an anti-inflammatory activity in subjects with metabolic disorders and of a pro-inflammatory activity in subjects allergic to bovine milk. Stratifying the data by product categories associated both low-fat and high-fat products, as well as fermented products, with an anti-inflammatory activity. Remarkably, the literature is characterized by a large gap in knowledge on bioavailability of bioactive nutrients. Future research should thus better combine food and nutritional sciences to adequately follow the fate of these nutrients along the gastrointestinal and metabolic axes

National audience; Riche d’un patrimoine fromager ancien et bénéficiant d’une forte notoriété, la Corse n’est pourtant pas en mesure aujourd’hui d’en définir et d’en garantir les qualités spécifiques. Sur les marchés insulaires et extérieurs, l’image très attractive de l’île donne lieu à des comportements spéculatifs controversés (importation de laits ou mise en œuvre de pratiques standardisées) à l’origine de conflits entre les différentes catégories professionnelles (entreprises fromagères, producteurs fermiers). La certification officielle de l’origine, pourtant identifiée par de nombreux acteurs comme un enjeu majeur, reste bloquée. Ce contexte, tendu et clivant, nourrit l’expression de légitimités concurrentes qui mobilisent des ressources différentes entre les producteurs fermiers, les artisans et les industriels et, sous d’autres modalités, les éleveurs fournisseurs de lait. Nous présentons les résultats d’une expérience de recherche participative conduite en Corse au sein de collectifs d’acteurs professionnels et associatifs. Elle permet d’analyser les dynamiques de légitimation des différentes catégories d’acteurs et les ressources qu’ils mobilisent pour mettre en valeur leurs fromages. Les conséquences de ces différentes dynamiques sur les formes d’organisation sont examinées dans la construction d’une chaine de valeur. Nous suggérons que cette construction procède d’un processus complexe de reconnaissance de chaque catégorie d’acteurs qui peut ouvrir des pistes de dépassement des conflits par l’établissement de controverses maîtrisées et documentées.

Erratum to: Dairy Sci. Technol.DOI 10.1007/s13594-014-0176-3In the original paper, the acknowledgements section should have read as follows:We are grateful to Mary Bret for the English correction of this paper and to Anne-LaureJacquet for her bibliographic assistance. We thank the “Agence Nationale de laRecherche et de la Technologie” for funding this work (Cifre contract reference2011/0574), the “Association de Coordination Technique pour l’Agro-alimentaire”and the “Unité Mixte de Technologie Caseolis” for their scientific support.; 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.

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.

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.

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

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

National audience

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.

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

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.

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, packaging). It is an “alive” actor in the cheese making process, interacting with the milk in the vats or with the cheeses placed on the shelves for ripening. Wood is alive 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 strongly requests deeper scientific investigation. In this review, knowledge about the multiple technological roles of wood in dairy technology, in particular its crucial role as reservoir of microbial biodiversity for traditional cheeses, as well as the results of safety assessments, will be presented. As a conclusion, the numerous questions remaining about this natural inoculating system will be discussed.

Lactobacillus helveticus and Propionibacterium freudenreichii are essential starters in Swiss cheesemaking and the release of their intracellular enzymes through autolysis could significantly influence ripening. To provide evidence of this lysis, cheese made from microfiltered thermized milk inoculated with Lb. helveticus ITGLH77, Prop. freudenreichii ITGP23 and a commercial Streptococcus thermophilus was assayed. Starter viability was determined and lysis was monitored during ripening by protein analysis with SDS-PAGE of aqueous cheese extracts and by immunoblot detection of intracellular proteins: dipeptidase (PepD) for Lb. helveticus and methylmalonyl coenzyme A mutase for Prop. freudenreichii. We verified that the species specificity of these lysis markers was towards the cytoplasms of all the species currently used in Swiss cheese. Lb. helveticus exhibited an almost complete loss of viability (99·9%) from the beginning of ripening in the cold room; concomitantly PepD appeared in the cheese extracts and was detected until the end of ripening. Damaged Lb. helveticus cells were also visualized by scanning electron microscopy. In addition, free PepD was also successfully detected in commercial Swiss-related cheeses. All these results clearly demonstrated the autolysis of Lb. helveticus in Swiss cheese. Prop. freudenreichii ITGP23 grew during warm room ripening and no loss of viability was detected after maximal growth (109 cfu/g cheese). Free methylmalonyl-coenzyme A mutase was detected at the end of ripening during cold storage, when the cheese extracts were concentrated 20-fold, demonstrating that the autolysis of Prop. freudenreichii was tardy and limited.

Free fatty acids (FFA) are important flavor compounds in cheese, where they contribute to pungent,rancid, cheesy, and fruity notes. They mainly result from the lipolytic activity of cheesemicroorganisms. In Swiss cheese, Propionibacterium freudenreichii, a species used as ripeningculture, is the main agent of lipolysis, with 96% of FFA released during ripening resulting from itsactivity. Our aim was to identify the esterase(s) involved in lipolysis by P. freudenreichii. Sincelipolysis in Swiss cheese mainly occurs during P. freudenreichii growth, we hypothesized that it doesnot result from the activity of intracellular enzymes released from lyzed cells, but from surfaceexposedor secreted esterases. Thus, we focused the present study on previously identifiedesterases, one secreted, PF#279, and one putative esterase predicted to be anchored in the plasmamembrane, PF#774. To evaluate the respective role of these two proteins in lipolysis,P. freudenreichii CIRM‐BIA1T was knocked out for the genes encoding these two proteins,separately. Each of these genes was also over‐expressed in the same strain. All genetically modifiedstrains were assessed for their lipolytic activity during their growth in a medium containing milk fatemulsion. In parallel, the lipolytic activity of 22 wild strains was also tested under the sameconditions, and the sequences of these two targeted genes compared among strains. We showedthat mutants over‐expressing either PF#279 or PF#774 released about three times more FFAcompared to the wild‐type strain (3.5 vs 0.9 mg/g fat), demonstrating that both enzymes arelipolytic esterases. However, only the mutant inactivated for PF#279 was affected in its lipolyticactivity. The lipolytic activity of the 22 wild strains tested varied over a large range (FFA netproduction ~ 0.05 to 1.9 mg/g fat). Interestingly, the two non lipolytic strains identified exhibitedthe same single deletion at the beginning of pf279 sequence, whereas pf774 sequence was highlyconserved among strains, confirming the prominent role of PF#279 in lipolysis. Taken together,these results show that PF#279 is the main lipolytic esterase involved in milk fat hydrolysis in P.freudenreichii and is likely a key component in Swiss cheese lipolysis.

National audience

The bacterial diversity occurring in traditional Minas cheese, made from raw milk, produced in four different regions of Minas Gerais state in Brazil, namely Cerrado, Araxa, Serro and Serra da Canastra, were evaluated by PCR–DGGE analysis of the V3 region of the bacterial 16S rDNA using primers previously described in the literature. Samples of Minas cheese made with pasteurized milk from Serro region were used as control. Bacterial DNA templates for PCR were directly extracted from cheese samples in a unique step. The PCR–DGGE revealed 1 band for the cheese samples made from pasteurized milk and 7 to 13 bands for those from traditional cheeses. Some bands were common for all cheeses and some were unique for each region. The results suggest that specific band profiles from traditional cheeses from each region may be used as a biological bar code to discriminate their origins. In addition, the band profiles clearly distinguished cheese made from pasteurized and raw milk. DGGE band sequencing analysis showed that species belonging to the genera Streptococcus may predominate in the traditional Minas cheese.