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Dhaka cheese is a semi-hard artisanal variety originating from Bangladesh, made mainly from bovine milk. Cheeses were produced in a pilot plant with different degrees of curd kneading to quantify the curd manipulation process in terms of pressure and to standardise the length of operation. Dhaka cheeses were also made with different levels of cheese surface pressure to evaluate the effects of pressing. A novel method of salting was also tested. The effect of manipulation on the composition, rheology, texture and microstructure of fresh cheese were studied. The results indicated that while manipulation had little effect on the composition, there were significant effects (P < 0.05 to 0.001) on most of the other parameters. One minute of manipulation was found to be sufficient for Dhaka cheesemaking. Curd was pressed at 0.00,5.2, 10.4, 15.6,20.8,26.0 and 31.2 kPa of gauge pressure for 12 hours at 24°C. Pressing at 15.6 kPa produced cheese with significantly (P < 0.05 to 0.001) better composition, texture and microstructure. The traditional salting method for Dhaka cheese, stuffing salt through 2 or 3 centrally bored holes extending from surface to centre, was compared with other methods. Dhaka cheeses were made using dry salting (l & 2%, w/w), brining (23% brine, w/w) , salt stuffing (1 & 2%, w/w) , and salt stuffing (l & 2%, w/w) plus brining. A significant variation (P < 0.001) in composition and texture was observed over seven days of observation. Three days of salting was found to be sufficient for the brined cheeses. The level of dry salt added to cheese should be at least 2%, w/w. The efficacy of the method of salting could be ranked as brining > salt stuffing plus brining > salt stuffing> dry salting.

This thesis develops an interpretation of 'the artisan' as practice, and through practice, taking as its particular case artisan cheese. It pays specific attention to food's materiality. Recognising the vitality of foodstuff, it destabilises conventional notions of the artisan as an exclusively human endeavour, in favour of an alternative construction of the artisan as that which comes together through multiple and heterogeneous human and non-human practices. Research is based on a multi-locale ethnography and extended periods of participant observation across a number of field sites, relating to the production, affinage and retail of artisan cheese. This approach permits an in-depth engagement with practice within and between sites, and with the particular contributions of food's lively matter. Each of the chapters explores distinct sites, tracing the inconsistencies and discontinuities of praxis and progressively decentring conventional conceptualisations of 'the artisan'. As the chapters unfold a thread is drawn out that allows these multiple practices to cohere, and around which an alternative account of what holds the artisan together is constructed. I identify this unifying thread as 'the ethic of regard', characterised by relations of response, curiosity and humility during quotidian encounters, and emergent in the precarious balance between responsiveness and control. This thesis engages with work on 'the artisan' and also with the extensive food studies literature. Artisan praxis is gradually driven out of these existing interpretations and, in an approach informed by post- and non-humanist studies, it is proposed that an appreciation of food as vital and potent matter, rather than as a static bearer of social meanings, can contribute to our understanding of the artisan as emergent in practice, through the coming together of people, materials and things.

This study characterised the bacterial flora of a commercially produced Stilton cheese in an effort to determine the contribution of non-starter lactic acid bacteria (NSLAB) to its aroma profile. A total of 123 microbial strains previously isolated from different sites (outer crust, blue veins and white core) of the cheese sample obtained at the end of ripening (~8 weeks) were recovered in MRS and BHI broths and preliminarily identified using conventional microbiological methods in order to establish population diversity and to screen out yeasts and moulds. Organisms identified with partial 16S rDNA sequence analysis were Lactobacillus plantarum, Lactobacillus brevis, Enterococcus faecalis, Staphylococcus aureus, Acinetobacter baumanii and Psychrobacter spp., with the genus Lactobacillus being the dominant (75%) group detected in all the sampled sites. Cluster analysis of pulse-field gel electrophoresis patterns associated the Lactobacillus isolates according to their site of isolation. Lb. plantarum isolates, two from each of the cheese sites, were evaluated for tolerance to heat stress and to different levels of salt, acid and relative humidity (RH) in order to ascertain whether the stress conditions associated with the isolation site could select the phenotype of microbial species recovered. The D72°C values revealed that isolates obtained from the outer crust were more heat sensitive suggesting they may have colonised the cheese post-pasteurisation. All the isolates were sensitive at pH range 3-4 but could grow at pH range 4.5-5. Similarly, isolates could grow at 3.5-5% (w/v) sodium chloride but were suppressed at 10%. Lactobacilli from the outer crust were the most halo-tolerant growing at 8% sodium chloride. For all strains, survival was low at 33-54% RH when cells were suspended in sterile de-ionised water but survived better at 33% RH in maximum recovery diluent (MRD) suggesting cellular protection by MRD. Lb. plantarum isolates from each site (outer crust=7; blue veins=19; white core=24) were tested for antimicrobial activity against Listeria monocytogenes, Escherichia coli, Pseudomonas aeruginosa, Staph. aureus, Salmonella Typhimurium, Clostridium sporogenes, Lb. pentosus and Lactococcus lactis using the plate agar overlay and paper disc diffusion assays. All the 59 Lactobacillus isolates were tested for plantaricin EF genes using PCR. The nature of antimicrobial activity was examined using cell-free supernatants treated to neutralise acids and/or hydrogen peroxide. Treatment with proteinase K was used to ascertain whether activity was due to bacteriocin (putative plantaricin) production. On solid medium, the isolates had antimicrobial activity against Gram-negative and Gram-positive bacteria, each isolate showing activity against more than one species. Lb. pentosus, Ps. aeruginosa, E. coli and L. monocytogenes were the most sensitive whereas Cl. sporogenes was the most resistant spp. Activity against these organisms was mainly attributed to acid, and to a less extent, hydrogen peroxide and plantaricin production. Whereas Lb. plantarum isolates had a high prevalence of plantaricin EF genes, there was weak evidence for plantaricin production in liquid medium assays. Plantaricin production was only demonstrable among Lb. plantarum isolates from the veins and core against Lb. pentosus, implying the phenomenon was largely dependent on the genotype/strain of Lb. plantarum and was only active against closely related lactic acid bacteria. Subsequently, the effect of growth and survival dynamics of the different genotypes of the organism on the volatile aroma profiles of milk was examined. Individual isolates, one from each of the cheese sites, were co-cultured with acid-producing Lc. lactis (APL) and non acid-producing Lc. lactis (NAPL) in UHT milk under simulated cheese ripening conditions. During early fermentation (0-48 h, 30oC), the isolate obtained from the blue veins stimulated more growth of Lactococcus strains in mixed culture when compared to single cultures and to Lactobacillus isolates obtained from other sites in mixed culture. The volatile profiles of all Lb. plantarum strains grown alone were not significantly different (p>0.05). The type and levels of volatiles detected in mixed culture depended on the genotype/strain of Lb. plantarum inoculated as well as the acidification capability of Lc. lactis with which it was co-cultured. Co-culture of Lactobacillus isolates with APL resulted in increased aldehyde and alcohol production, whereas with NAPL only acetoin synthesis was enhanced. Salt addition had minimal effect on the volatile profiles. During further incubation (12 weeks, 18oC), growth of Lb. plantarum strains was better in salted samples inoculated with NAPL. The NAPL strain remained stable at 7 log10 CFU/ml throughout, while the APL rapidly declined from 9 to less than 5 log10 CFU/ml. The highest level of alcohols, organic acids and acetoin was detected from samples inoculated with the pure culture of the Lactobacillus isolate obtained from the blue veins. Co-culture of the isolate with APL enhanced acid and alcohol production, whereas its co-inoculation with NAPL increased acetoin synthesis. As Lb. plantarum is an incidental organism in cheese, its presence is unpredictable; it was therefore concluded that occurrence of different genotypes of the organism could be a major contributory factor to the variations in the cheese quality characteristics from batch to batch.

Η φέτα είναι είδος τυριού στην άλμη, τις ρίζες της οποίας τις βρίσκουμε χιλιάδες χρόνια πριν στην Αρχαία Ελλάδα. Παρασκευάζεται αποκλειστικά από γάλα προβάτου ή αιγοπρόβειο, δηλαδή μείγμα με έως 30% γάλα κατσίκας. Με βάση την παραδοσιακή μέθοδο παρασκευής της φέτας παρασκευάστηκε ένα νέο τυρί τύπου φέτας με την προσθήκη φλοιού σιταριού ο οποίος χρησιμοποιήθηκε για την ακινητοποίηση των κυττάρων του προβιοτικού μικροοργανισμού L.casei ATCC 393. O ακινητοποιημένος βιοκαταλύτης προστέθηκε ξεχωριστά κατά τη διάρκεια παρασκευής του τυριού τύπου φέτα στος 37 oC Στόχος του πειράματος ήταν η δημιουργία ενός νέου τυριού άλμης στο οποίο θα προσδίδονταν νέες προβιοτικές αλλά και πριβιοτικές ιδιότητες. Πέρα του τυριού με τον ακινητοποιημένο βιοκαταλύτη (L.casei και φλοιός σιταριού) για λόγους σύγκρισης παρασκευάστηκαν 3 ακόμη διαφορετικά τυριά άλμης, μια παραδοσιακή φέτα, ένα τυρί τύπου φέτας με ελέυθερο τον προβιοτικό μικροοργανισμό L.casei και ένα τυρί τύπου φέτας με προσθήκη φλοιού σιταριού. Στα παραγόμενα προϊόντα μελετήθηκε η επίδραση του ακινητοποιημένου βιοκαταλύτη στα φυσικοχημικά τους χαρακτηριστικά, καθώς και στο μικροβιολογικό και οργανοληπτικό τους προφίλ κατά τη διάρκεια αποθήκευσής τους για διάστημα 65 ημερών. Η βιοσιμότητα του L. casei εξετάστηκε επίσης. / Feta is a kind of cheese in brine, which was first found in ancient Greece thousands of years ago. It is made from sheep’s milk or mixture of sheep’s and goat’s milk which conclude up to 30% goat’s milk.According to the traditional method which is used in feta manufacture a new kind of feta cheese was produced. In this kind of feta cheese wheat bran was used for the immobilization of L. casei ATCC 393 cells. The immobilized biocatalysts were separately added as adjuncts during cheese type “Feta” production at 37oC.Τhe main purpose of conducting this experiment was producing a new type of cheese in brine in which new probiotic and pribiotic characteristics would be transfused. For comparison reasons cheeses with and without free L. casei cells were prepared as well as a traditional feta cheese. The effect of the immobilized biocatalysts as adjuncts at cheeses on physicochemical parameters, microbiological and organoleptic characteristics were studied for 60 storage days. The viability of L. casei during storage was also studied

Ces travaux de thèse portent sur l'étude pluridisciplinaire (biochimique, physicochimique, microbiologique) de l'amélioration des qualités aromatiques du Poro, fromage artisanal mexicain au lait cru, afin d'en allonger sa durée de commercialisation sur le marché mexicain. Pour cela, après une caractérisation physicochimique du fromage, différentes techniques d'encapsulation dans l'enrobage de paraffine du fromage ont été testées. Par ailleurs, l'activité inhibitrice de Carnobacterium maltaromaticum LMA28, isolée à partir d'un fromage à pâte molle, a aussi été étudiée vis-à-vis de L. monocytogenes pour une application en industrie fromagère. L'évaluation sensorielle a permis de construire une cartographie des préférences internes pour le fromage Poro. Dans un second temps nous nous sommes intéressée à masquer l'apparition de défauts olfactifs dans le Poro : L'encapsulation de C. maltaromaticum LMA28 est une meilleure alternative pour la libération de 3-méthylbutanal par rapport à l'encapsulation directe du 3-méthylbutanal. Enfin, d'un point de vue microbiologique, aucune trace de contamination fécale n'a été retrouvée dans les produits. Les principales souches de bactéries lactiques isolées dans le fromage ont été : L. plantarum, L. pentosus, L. farciminis, L. rhamnosus. L'effet de quatre facteurs (C. maltaromaticum, concentration en NaCl, temps et pH) et de leurs interactions sur la croissance de L. monocytogenes inoculée dans deux milieux de culture (TSB- YE et lait écrémé) a été étudié. La concentration de C. maltaromaticum LMA28 s'est révélée être le facteur déterminant pour obtenir une inhibition de L. monocytogenes dans les deux milieux de culture testés / This thesis focuses on the interdisciplinary study (biochemical, physicochemical, microbiological) in order to improve sensory qualities and, more specifically, aromatic profile of Poro cheese in order to extend its commercialization period on the Mexican market. After cheese characterization, several encapsulations techniques were tested into cheese paraffin coating. Moreover, inhibitory activity of C. maltaromaticum LMA28 isolated from a soft cheese against L. monocytogenes was also studied. Sensory evaluation led to a preferences internal mapping. It appeared that C. maltaromaticum LMA28 encapsulation was a better alternative for the 3-methylbutanal release compared with 3-methylbutanal direct encapsulation to improve off-flavor apparition in Poro. Sensory experiments performed on Babybel® (cheese model) showed a difference between the sensory perceptions of cheese coated containing or not C. maltaromaticum LMA28. Micro-encapsulation in calcium alginate is a quick encapsulation technique, simple, inexpensive and easy to implement even for a small-scale productions. Finally, from a microbiological point of view, no trace of fecal contamination was found in the products. The main strains of lactic acid bacteria isolated were cheese: L. plantarum, L. pentosus, L. farciminis, and L. rhamnosus. The effect of four factors (C. maltaromaticum, NaCl concentration, time and pH) on L. monocytogenes growth, inoculated into two culture media (TSB -YE and skim milk). The C. maltaromaticum LMA28 concentration appeared to be the determining factor for L. monocytogenes inhibition in both media tested

Les aptitudes du lait à la transformation en fromage sont étroitement liées à sa composition, notamment en protéines. Ces caractères, difficiles à mesurer directement, ont été prédits à partir des spectres moyen infrarouge (MIR) du lait pour la composition en protéines dans les 3 races bovines Montbéliarde, Normande et Holstein (projet PhénoFinlait) et pour 9 aptitudes fromagères et la composition fine du lait en race Montbéliarde (projet From’MIR). La méthode Partial Least Squares (PLS) a fourni des prédictions MIR plus précises que les méthodes bayésiennes testées.Une analyse génétique a été réalisée pour ces caractères prédits à partir de plus de six millions de spectres MIR de plus de 400 000 vaches.Les caractères fromagers et de composition du lait sont modérément à fortement héritables. Les corrélations génétiques entre caractères fromagers (rendements et coagulation) et avec la composition du lait (protéines, acides gras et minéraux) sont élevées et favorables.Les génotypes de 28 000 vaches ont été imputés jusqu’à la séquence complète grâce aux données du projet 1000 génomes bovins.Des analyses d’association (GWAS) révèlent de nombreux gènes et variants avec des effets forts sur la fromageabilité et la composition du lait. Un réseau de 736 gènes, par ailleurs associé à ces caractères, permet d’identifier des voies métaboliques et des gènes régulateurs fonctionnellement liés à ces caractères.Un prototype d’évaluation génomique a été mis en place en race Montbéliarde. Un modèle de type contrôles élémentaires, incluant les variants détectés par les GWAS et présumés causaux, donne les estimations des valeurs génomiques les plus précises. La simulation d’une sélection incluant les caractères fromagers montre qu’il est possible d’améliorer la fromageabilité du lait avec un impact limité sur le gain génétique des autres caractères sélectionnés.Les travaux présentés dans cette thèse ont abouti 1) à la détection de gènes (dont certains jamais décrits auparavant) et de variants candidats pour la composition et la fromageabilité du lait et 2) à la mise en place d’une évaluation génomique de la fromageabilité du lait en race Montbéliarde dans la zone AOP Comté. / The ability of milk to be processed into cheese is closely linked to its composition, in particular in proteins. These traits, which are difficult to measure directly, were predicted from milk mid-infrared (MIR) spectra for protein composition in 3 cattle breeds Montbéliarde, Normande and Holstein (PhénoFinlait project) and for 9 milk cheese-making properties (CMP) and composition traits in Montbéliarde cows (From’MIR project). The Partial Least Squares method provided more accurate predictions than the Bayesian methods tested.A genetic analysis was performed on these traits, predicted from more than six million MIR spectra of more than 400,000 cows.Milk CMP and composition traits are moderately to highly heritable. Genetic correlations between CMP (cheese yields and coagulation) and with milk composition (proteins, fatty acids and minerals) are high and favorable.The genotypes of 28,000 cows were imputed to whole genome sequences using the 1000 bovine genome reference population.Genome wide association studies (GWAS) reveal many genes and variants in these genes with strong effects on CMP and milk composition. A network of 736 genes, associated with these traits, enable the identification of metabolic pathways and regulatory genes functionally linked to these traits.A pilot genomic evaluation was set up in Montbéliarde cows. A test-day model, including variants detected by GWAS, provides the most accurate genomic value estimates. Simulation of a selection shows that it is possible to improve the cheesability of milk with a limited impact on the genetic gain of the traits that currently make up the breeding objective.The work presented in this thesis led to 1) the detection of genes (some of which have never been described before) and candidate variants for milk CMP and composition traits and 2) the implementation of a genomic evaluation of CMP predicted from MIR spectra in Montbéliarde cows of the Comté PDO area.