Automatic marbling prediction of sliced dry-cured ham using image segmentation, texture analysis and regression

Dry-cured ham is a traditional Mediterranean meat product consumed throughout the world. This product is very variable in terms of composition and quality. Consumer’s acceptability of this product is influenced by different factors, in particular, visual intramuscular fat and its distribution across the slice, also known as marbling. On-line marbling assessment is of great interest for the industry for classification purposes. However, until now this assessment has been traditionally carried out by panels of experts and this methodology cannot be implement in industry. We propose a complete automatic system to predict marbling degree of dry-cured ham slices, which combines: (1) the color texture features of regions of interest (ROIs) extracted automatically for each muscle; and (2) machine learning models to predict the marbling. For the ROIs extraction algorithm more than the 90% of pixels of the ROI fall into the true muscle. The proposed system achieves a correlation of 0.92 using the support vector regression and a set of color texture features including statistics of each channel of RGB color image and Haralick’s coefficients of its gray-level version. The mean absolute error was 0.46, which is lower than the standard desviation (0.5) of the marbling scores evaluated by experts. This high accuracy in the marbling prediction for sliced dry-cured ham would allow to deploy its application in the dry-cured ham industryThis work has received financial support from the Xunta de Galicia (Centro singular de investigación de Galicia, accreditation 2020– 2023) and the European Union (European Regional Development Fund–ERDF), Project ED431G-2019/04. IRTA’s contribution was also funded by the CCLabel project (RTI-2018- 096883-R-C41) and the CERCA programme from Generalitat de CatalunyaS

Instrumental texture analysis on the surface of dry-cured ham to define the end of the process

The end of the elaboration process of dry-cured ham is currently decided by product weight loss and/or by an expert who carries out an evaluation of the tactile texture on the surface. The objective of this study was to define the optimal measurement conditions of an instrumental texture analysis on the surface of the dry-cured ham (ITAS), to define the end of process. 120 dry-cured hams were classified by experts into Hard (appropriate) or Soft (non-appropriate) texture groups and used to perform compression tests using different probes on three anatomical positions. Results showed that the small probe in position 2 gave the most discriminant conditions, providing representative information of the internal texture. Although classification using only weight loss was possible with an accuracy rate of 80.4 % or 66.7% depending on the weight loss, the maximum classification accuracy was obtained when using ITAS in combination with weight loss. Further studies at industrial level are needed.info:eu-repo/semantics/acceptedVersio

Development and evaluation of tools to improve the texture and quality of dry-cured ham

El jamón curado es considerado un producto típico de la región mediterránea elaborado con las patas traseras del cerdo, las cuales se salan y curan durante un período largo. Sin embargo, existen otros productos curados como el jamón curado de cordero, el Fenalår, típico de Noruega, que se sala, se ahúma y se cura durante un período más corto de tiempo. La textura de los productos curados es un criterio de calidad importante para los consumidores. Sin embargo, el desarrollo de la textura, así como también de los defectos de textura de los productos curados tanto de cerdo como de cordero son un tema complejo puesto que hay muchos factores involucrados. Por este motivo, hay un interés creciente de la industria alimentaria en encontrar soluciones para reducir la incidencia de productos con texturas blandas y/o defectuosas.El principal objetivo de esta Tesis es desarrollar y evaluar herramientas para mejorar el proceso de elaboración y la calidad de dos productos curados: el jamón curado y el Fenalår. Para ello, se han llevado a cabo diferentes estudios los cuales se presentan en esta Tesis en diferentes artículos científicos. El artículo I aborda los principales factores que afectan al desarrollo de la textura y a la modelización de la textura. El segundo artículo muestra los resultados de la microbiología predictiva utilizada para estudiar la seguridad alimentaria en relación con el proceso de elaboración y la reducción del contenido de sal, así como también la omisión de nitrificantes (artículo II). En el artículo III se investigó un método para evaluar de manera no destructiva el punto final del proceso en función de las medidas obtenidas en la superficie del jamón. En el artículo IV,se presentan los resultados obtenidos de un primer intento para el desarrollo de un método para evaluar la pastosidad con el reómetro y evitar así los tediosos análisis sensoriales. Finalmente, el uso de un tratamiento de altas presiones como acción correctora para productos con texturas defectuosas se presenta en el artículo V.Con la finalidad de estudiar de forma más detallada el desarrollo de la textura, se desarrolló un modelo matemático (artículo 1), que relaciona las condiciones de procesado y las características de la materia prima con la textura del producto. Este modelo no sólo permite evaluar el efecto de estos factores, sino que también podría permitir una optimización del proceso de elaboración a nivel industrial. Los resultados mostraron que el contenido de sal, el pH, las características de la materia prima y las condiciones de procesado (temperatura de secado y merma final) son factores importantes que afectan al desarrollo de la textura, tal y como se presenta en el artículo I, y a la vez comprometen la seguridad del producto. En el artículo II, la reducción del contenido de sal no sólo dio como resultado texturas más blandas, sino que también produjo un incremento de los riesgos microbiológicos, especialmente cuando se omitieron los nitrificantes, tal y como muestran los resultados obtenidos mediante los modelos de microbiología predictiva. Además, los defectos de textura en ambosproductos curados representan un importante desafío para la industria.A pesar de los esfuerzos realizados para mejorar el proceso de elaboración, es posible que algunos productos sigan siendo defectuosos, evidenciando así la necesidad de nuevas herramientas y/o tecnologías con potencial para su aplicación a nivel industrial. En esta Tesis, se estudió una metodología para evaluar si el producto tenía o no la textura adecuada para su comercialización (artículo III), así como también un análisis para evaluar instrumentalmente el defecto de pastosidad en jamón curado loncheado (papel IV). Los resultados presentados en el artículo III muestran que el método ITAS permitió evaluar de manera no destructiva el punto final del proceso; esta metodología consiste ensimular la valoración táctil en la superficie del jamón realizada actualmente por los expertos. La máxima precisión de clasificación fue del 82,1%, obtenida al combinar las mediciones junto con el espesor de la grasa subcutánea. La implantación de esta tecnología a nivel industrial no sólo mejoraría la calidad del producto, sino que también supondría un ahorro económico, energético y de espacio, ya que permitiría un mejor ajuste del tiempo de secado necesario para cada jamón.En el artículo IV se presentan los resultados obtenidos en un primer estudio para el desarrollo de un método para evaluar la pastosidad utilizando un reómetro. Los resultados obtenidos mostraron un aumento de la viscosidad de los extractos a medida que aumentaba la intensidad del defecto de pastosidad, mostrando así la posibilidad de detectar instrumentalmente este defecto utilizando el reómetro. Sin embargo, hay otros factores a parte de la viscosidad que pueden afectar/alterar los resultados y el reómetro sólo permite discriminar las muestras con una pastosidad intensa de aquellas que tienen un defecto medio o que no son pastosas.También se han llevado a cabo acciones correctoras en lonchas de jamón curado utilizando tratamientos mediante altas presiones a diferentes temperaturas (artículo V).Los resultados obtenidos muestran que, si bien las temperaturas de 7 ºC y 20 ºC son útiles para corregir el defecto en las lonchas con pastosidad media, se necesita una temperatura superior (35 ºC) para las de pastosidad intensa. Por lo tanto, conocer las características iniciales de textura del producto es clave para definir las condiciones óptimas para su procesado mediante altas presiones cuando se busca mejorar la textura sin deteriorar el color ni el aroma.Las metodologías desarrolladas y evaluadas en esta Tesis pueden utilizarse para mejorar el proceso de elaboración y la calidad del jamón curado. Además, representan un primer paso en el desarrollo de nuevas herramientas para uso industrial.Dry-cured ham is considered a typical product of the Mediterranean area made of pig¿s hind leg which is dry-salted and has a long maturation period. However, there are other typical dry-cured products such as the dry-cured lamb ham, Fenalår, from Norway, which is dry-salted and smoked followed by a short maturation period. The texture of dry-cured products is an important quality criterion for the consumers. However, texture development and also texture defects of dry cured products from both pork and lamb are a complex issue since many factors are involved. For this reason, there is an increasing interest of the industry in finding solutions to reduce the incidence of products with soft and/or defective textures. The main objective of this PhD Thesis dissertation was to develop and evaluate tools to improve the manufacturing process and the quality of two examples of dry-cured products; dry-cured ham and Fenalår. For this reason, different studies were conducted and herein presented as different papers. First one addresses the main factors affecting texture development and texture prediction modelling (presented in paper I). The second paper presents the results of predictive microbiology used to study food safety in relation to manufacturing process with reduced salt and nitrites addition (in paper II). Next study investigated a method to non-destructively evaluate the end of process based on the measurements taken at the surface of the ham (in paper III). The results of an attempt to develop a method to evaluate pastiness with a rheometer to avoid the tedious sensory analysis are presented in paper IV. Finally, the use of high pressure treatments as a corrective action for products with defective textures is presented in paper V. In order to study texture development in more detail, mathematical models were developed (paper I), that relate processing conditions and raw material characteristics to the texture of the product. These models not only allow the effect of these factors to be evaluated but could also enable further optimisation of the process in the industry. The results showed that salt content, pH, raw material characteristics and processing conditions (drying temperature and final weight loss) are important factors affecting texture development, as shown in paper I, while affecting product safety. In paper II, reduced salt content not only resulted in softer textures but also in an increase of microbiological hazards especially when no nitrite was used as evaluated by predictive microbiology models. Furthermore, texture defects in both dry-cured products represent an important challenge for the industry. Despite the efforts to improve the manufacturing process, some products may still be defective and the need for new tools and/or technologies with potential for industrial application is emerging. In this Thesis, a methodology to evaluate whether the product had the appropriate texture to be sent to the market or not (paper III) and an analysis to instrumentally evaluate pastiness defect in sliced dry-cured ham (paper IV) were studied. Results presented in paper III show that ITAS method allowed to non-destructively assess processing end point; this methodology consist of simulating the tactile assessment of ham surface as currently made by the experts. The maximum classification accuracy was 82.1% obtained when combining measurements with subcutaneous fat thickness. The implementation of this technology in industry would not only improve the quality of the product but also economic, energy and space savings, as it would enable better adjustment of required drying time for each ham. Results of the study in paper IV represent a first attempt for the development of a method to evaluate pastiness using a rheometer to avoid the tedious sensory analysis. An increase in viscosity of water extracts with an increase in pastiness intensity, show the ability to instrumentally detect this defect using the rheometer. However, there are factors other than viscosity that can affect/alter the results and this method allows discriminating only samples with high pastiness intensity from those with medium or non-pastiness defect. Corrective actions for dry-cured ham slices using HPP treatments at different temperatures were also analysed (paper V). The obtained results show that while temperatures of 7 ºC and 20 ºC are useful to correct ham slices with medium pastiness, higher temperature (35 ºC) is needed in the case of high pastiness. Therefore, knowing textural properties of the product is key information to define optimal HP processing conditions when aiming to improve texture without deteriorating colour and aroma. The methodologies developed and evaluated in the present work can be used to improve the manufacturing process and quality of dry-cured ham. They represent a first step in development of new tools for industrial use. <br /

Magnetic Resonance Imaging, texture analysis and regression techniques to non-destructively predict the quality characteristics of meat pieces

The quality of meat products is traditionally assessed by chemical or sensorial analysis, which are time consuming, need specialized technicians and destroy the products. The development of new technologies to monitor meat pieces using non-destructive methods in order to establish their quality is earning importance in the last years. An increasing number of studies have been carried out on meat pieces combining Magnetic Resonance Imaging (MRI), texture descriptors and regression techniques to predict several physico-chemical or sensorial attributes of the meat, mainly different types of pig ham and loins. In spite of the importance of the problem, the conclusions of these works are still preliminary because they only use the most classical texture descriptors and regressors instead of stronger methods, and because the methodology used to measure the performance is optimistic. In this work, we test a wide range of texture analysis techniques and regression methods using a realistic methodology to predict several physico-chemical and sensorial attributes of different meat pieces of Iberian pigs. The texture descriptors include statistical techniques, like Haralick descriptors, local binary patterns, fractal features and frequential descriptors, like Gabor or wavelet features. The regression techniques include linear regressors, neural networks, deep learning, support vector machines, regression trees, ensembles, boosting machines and random forests, among others. We developed experiments using 15 texture feature vectors, 28 regressors over 4 datasets of Iberian pig meat pieces to predict 39 physico-chemical and sensorial attributes, summarizing16,380 experiments. There is not any combination of texture vector and regressor which provides the best result for all attributes tested. Nevertheless, all these experiments provided the following conclusions: (1) the regressor performance, measured using the squared correlation (R2), is from good to excellent (above 0.5625) for 29 out of 39 attributes tested; (2) the WAPE (Weighted Absolute Percent Error) is lower than 2% for 32 out of 37 attributes; (3) the dispersion in computer predictions around the true attributes is lower or similar than the dispersion in the labeling expert’s for the majority of attributes (85%); and (4) differences between predicted and true values are not statistically significant for 29 out of 37 attributes using the Wilcoxon ranksum statistical test. We can conclude that these results provide a high reliability for an automatic system to predict the quality of meat pieces, which may operate on-line in the meat industries in the futureThe authors wish to acknowledge the funding received from the FEDER-MICCIN Infrastructure Research Project (UNEX-10-1E-402), Junta de Extremadura economic support for research group (GRU15173 and GRU15113), from the Xunta de Galicia (Centro singular de investigación de Galicia accreditation 2016–2019) and from the European Union (European Regional Development Fund — ERDF)S

Evaluation of live growing pigs of different genotypes and sexes using computed tomography

Conocer la composición corporal en animales vivos y la deposición de los diferentes tejidos durante su crecimiento es de vital importancia para, entre otras cosas, caracterizar el efecto de una genética, la condición sexual, el manejo e incluso analizar la eficiencia alimentaria y adecuar la dieta a cada estadio de crecimiento, ya que la composición en tejido graso y muscular del cuerpo de los animal está influenciada tanto por factores intrínsecos como extrínsecos. La aplicación de la tomografía computerizada (CT) en animales vivos permite analizar, de manera no invasiva, la evolución de la composición corporal de un mismo animal a lo largo del período de crecimiento. Esto permite modelizar el crecimiento y desarrollo de los diferentes tejidos del cuerpo sin necesidad alguna de sacrificar el animal. Esta tesis propone conocer la evolución de la composición corporal de cerdos de distintas genéticas (experimento 1) o sexos (experimento 2). El experimento 1 estaba formado por 90 animales de tres genéticas distintas (todas ellas comerciales y altamente utilizadas en el sector), y el experimento 2 estaba formado por 92 animales de cuatro condiciones sexuales distintas (hembras (FE), machos enteros (EM), machos castrados quirúrgicamente (CM) y machos inmunocastrados (IM)). Los animales se evaluaron con el CT a 30, 70, 100 i 120 kg de peso objetivo. Una submuestra de animales de cada genética y sexo (n=5/genética y n=4/sexo) se sacrificaron a los diferentes pesos objetivo y se disecaron total o parcialmente. El resto de animales (animales de seguimiento), se evaluaron con el CT a cada peso objetivo y, al llegar a 120 kg, se sacrificaron. A partir de los animales sacrificados y disecados, se obtuvieron ecuaciones de predicción, de la composición corporal y de las diferentes piezas, que se usaron en el resto de animales de seguimiento. Las predicciones se hicieron para cada genética independientemente (Chapter 4) o bien generalizadas para todas las genéticas y sexos (Chapter 6). Ambas ecuaciones fueron adecuadas para la predicción de la composición corporal (Chapter 8). En este sentido, presentar las predicciones individuales según la genética reduce el error (RMSE entre 0.011 y 0.886). No obstante, la ecuacion global permite generalizar las predicciones para un mayor número de animales, así pues, es preferible usarla cuando la población está mezclada o cuando el parámetro estimado no requiere un alto valor de precisión. Cuando esta precisión se requiere, como es el caso de compañías genéticas, es preferible utilizar las ecuaciones individuales, específicamente desarrolladas para cada genética. Los resultados muestran que los tejidos crecen de manera diferente según la genética s y el sexo (Chapter 5 y 7). El tejido que mostró el mayor coeficiente alométrico fue la grasa, indicando el índice de deposición más rápido de este tejido. De entre las distintas genéticas, LA fue quien mostró la deposición de grasa más rápida (Chapter 5), mientras que respecto a los sexos, los CM e IM fueron los que tuvieron un índice de deposición de grasa más elevado y más lento en los EM y FE (Chapter 7). El comportamiento de la deposición de magro fue inverso al de la grasa. Añadir que, los IM y CM tuvieron un comportamiento muy similar respecto a la velocidad de deposición de grasa y magro, a pesar que los IM se comportaron como los EM hasta que recibieron la segunda dosis de la vacuna de immunocastración. Finalmente, en las condiciones de realización de este trabajo se puede concluir que el CT puede ser muy útil para la industria cárnica, porque los parámetros de calidad y composición de la canal se pueden conocer a pesos muy tempranos. Como resultado, el uso de esta información puede aportar beneficios económicos para todos los integrantes de la cadena alimenticia.Knowledge of the composition of animal bodies and animal tissue growth is very important for the characterization of the effect of a genotype, the sexual condition, the management or to analyze the feed efficiency and adjust the diet to growth states, because fat and lean composition are dependent on intrinsic and extrinsic factors. The application of computed tomography (CT) to living animals allows analyzing non-invasively the evolution of the body composition of a single animal through its growing period. Subsequently, growth and development of the different body tissues can be modeled, without the necessity to slaughter the animal. The PhD Thesis at hand investigates the evolution of the composition of pig bodies from different genetic types (experiment 1) and sexual conditions (experiment 2). Experiment 1 was performed on 90 pigs of three genetic types (all of them were commercial and very used in the swine industry), while experiment 2 was performed on 92 animals with four different sexual conditions (females, entire males, castrated males and immunocastrated males). The animals were scanned by CT at 30, 70, 100 and 120 kg live weigh. One subsample for each genetic type and sexual condition (n=5/genetic type and n=4/sexual condition) were slaughtered at the different target weights and were fully or partially dissected. The rest of the animals (animals of the study) were evaluated with the CT at each target weight and, once they reached 120 kg, they were slaughtered. Knowledge gained from slaughtered and dissected animals was used to formulate prediction equations for body and pieces composition. They were then applied to the animals of the study. Predictions were performed independently for each genetic type (Chapter 4) or generalized for all the genetic types and sexual conditions of this work (Chapter 6). Both equations produce good results for the prediction of body composition (Chapter 8). Presenting the individual predictions depending on the genetic type reduces the error (RMSE between 0.011 and 0.886). However, the global equation allows generalizing the predictions for a bigger number of animals, thus, it has preference if the population is mixed or if high level of accuracy is not required. If high accuracy is needed, for instance for genetic companies, individual equations specifically developed for each genetic type are prefered. Results show that tissues grow different depending on the genetic type and sexual condition (Chapter 5 and 7). Tissue that shows the highest allometric coefficient was the fat, corresponding to the fastest deposition. From the different genotypes, LA was the one that shows the fastest deposition of fat (Chapter 5). With respect to the sexual condition, CM and IM exert the highest deposition value for the fat, with EM and FE showing the lowest (Chapter 7). Lean tissue behaves in the opposite way as fat. The IM and CM had a very similar behavior with respect to the deposition speed of fat and lean, even IM behave as EM until the study animals received the second dose of the immunocastration vaccine. In conclusion, CT can be very useful for the meat industry due to its ability to predict quality parameters, as well as carcass composition, at early growth stage. This technique can thus bring economic benefits for all the livestock and food chain industry

Proceedings of the 6th International Symposium on the Mediterranean Pig. October 11 – 13, 2007. Messina - Capo d’Orlando (ME), Italy

These proceedings publish 79 communications that were distributed in six sessions and in one conference at the 6th Symposium on the Mediterranean Pig, both as main lectures, oral and poster presentation. The major arguments treated are the improvement and the management of the genetic resources, the sanitary approaches in the outdoor systems, the feeding and the rearing techniques, the quality of meat and meat products, the traceability for typical products and their socio-economical dynamics. Particular attention is given to the pig's local breeds and to their meat products, highlighting the importance to preserve the biodiversity as well as the typicality of some unique pork products. The monitoring of pig parasitic diseases is examined as well as the non conventional rearing systems used for typical pig breeds and their effects on the pork quality. It is highlighted also the importance of the products traceability and the need to better understand the purchasing dynamics of typical pork products

Proceedings of the 6th International Symposium on the Mediterranean Pig. October 11 – 13, 2007. Messina - Capo d’Orlando (ME), Italy

These proceedings publish 79 communications that were distributed in six sessions and in one conference at the 6th Symposium on the Mediterranean Pig, both as main lectures, oral and poster presentation. The major arguments treated are the improvement and the management of the genetic resources, the sanitary approaches in the outdoor systems, the feeding and the rearing techniques, the quality of meat and meat products, the traceability for typical products and their socio-economical dynamics. Particular attention is given to the pig's local breeds and to their meat products, highlighting the importance to preserve the biodiversity as well as the typicality of some unique pork products. The monitoring of pig parasitic diseases is examined as well as the non conventional rearing systems used for typical pig breeds and their effects on the pork quality. It is highlighted also the importance of the products traceability and the need to better understand the purchasing dynamics of typical pork products

Effet du salage et du séchage sur la dynamique d’évolution de la protéolyse, de la structure et de la texture lors de la fabrication d’un jambon sec. Développement d’un modèle de « jambon numérique » couplant transferts d’eau, de sel et protéolyse

Because of public health problems, the food industry must lower sodium content in all food products, therefore in cured meat products. During the dry-cured ham elaboration process, decreasing salt content may induce microbial safety problems and texture defects due to an excessive proteolysis that could affect later the industrial stage of slicing. On account of that, this work of thesis aims at (1) studying the relationship between proteolysis, structure and texture during the various stages of dry-cured ham manufacture, and (2) building a “numerical ham” model to predict spatially the time course of water and salt content, and thus water activity (a w ), and to couple these variations with proteolysis. This work combines experimental studies and numerical modelling and simulation. Firstly, a new and powerful technique for quantifying proteolysis that uses “Fluorescamine” was developed and validated on pork meat samples and samples extracted from industrial dry-cured hams; a new proteolysis index (PI) was defined. Based on an experimental design, the time course of proteolysis was quantified in laboratory-salted and dried pork meat samples prepared from five different types of pork muscle. Applying multiple linear regression enabled us to build phenomenological models relating, for each pork muscle, PI velocity to temperature, and to water and salt content. Using Comsol ® Multiphysics software, these phenomenological models were then combined with heat and mass transfer models and associated with calculation of a w , thus constituting the “numerical ham” model. In addition, the time course of PI, five textural parameters (hardness, fragility, cohesiveness, springiness and adhesiveness), and four structural parameters (fiber number, extracellular spaces, cross section area, and connective tissue area) was quantified on samples extracted from two different muscles of industrial dry-cured hams removed from the process at five different processing times. Multiple polynomial regression was applied to build phenomenological models relating PI, salt and water content to some textural and structural parameters investigated. These last models could be rapidly incorporated in the “numerical ham” model to constitute a real process simulator. In the future, the “numerical ham” model should be improved in order to take into account (1) the strong decrease in ham volume due to drying and also (2) the decrease in proteolysis velocity with time as a result of the reduction in the amount of protein that can be hydrolysed in the ham. Once completed and improved, the process simulator will be available to professionals to test scenarios allowing sodium content to be reduced in dry-cured hams without altering their final quality.Du fait de problèmes de santé publique, l’industrie agroalimentaire doit réduire la quantité de sel (chlorure de sodium) dans les aliments, et donc dans les charcuteries. Lors de la fabrication des jambons secs, une diminution du taux de sel pourrait se traduire par des problèmes de texture dus à une protéolyse excessive pouvant nuire à l’étape de tranchage industriel, et aussi par des problèmes de stabilité microbiologique. Dans ce contexte, les objectifs de cette thèse sont : (1) d’étudier le lien entre l’évolution de la protéolyse, de la texture et de la structure, tout au long des différentes étapes de fabrication de jambons secs et (2) de développer un modèle de « jambon numérique » afin de prédire spatialement les dynamiques d’évolution des teneurs en eau, en sel et celle de l’activité de l’eau (a w ), et de coupler ces évolutions à celle de la protéolyse. Ce travail combine études expérimentales et modélisation/simulation numérique. Tout d’abord, une méthode de quantification de la protéolyse utilisant la « Fluorescamine » a été développée et validée sur des échantillons de viande de porc et des échantillons extraits de jambons industriels ; un nouvel indice de protéolyse (IP) a été défini. Sur la base d’un plan d’expériences, l’évolution de la protéolyse au sein d’échantillons différemment salés et séchés et préparés à partir de 5 muscles différents d’un jambon de porc, a été quantifiée. Suite à l’application d’une régression linéaire multiple, des lois phénoménologiques ont été construites permettant de calculer la vitesse de protéolyse, pour un muscle donné, en fonction de la température et des teneurs en eau et en sel. Ensuite, au moyen du logiciel Comsol ® Multiphysics, ces lois ont été combinées avec des modèles de transferts de matière (eau, sel), de chaleur (température), et de calcul de l’a w , constituant ainsi un modèle de « jambon numérique ». Enfin, la dynamique d’évolution de l’IP, de 5 paramètres texturaux (dureté, fragilité, cohésion, élasticité et adhésion) et de 4 paramètres structuraux (nombre des fibres, espaces extracellulaires, taille des fibres et surface de tissu conjonctif) a été mesurée sur des échantillons prélevés dans deux muscles extraits de jambons industriels pris à cinq stades de fabrication différents. L’application d’une régression polynômiale multiple à ces données expérimentales a conduit à l’établissement de corrélations permettent de calculer certains paramètres texturaux et structuraux à partir de l’IP et des teneurs en eau et en sel. A court terme, ces lois seront incorporées dans le modèle numérique afin de constituer un vrai simulateur de procédé. A moyen terme, le modèle de « jambon numérique » devra être amélioré afin de tenir compte (1) de la diminution du volume du jambon, du fait du séchage et (2) de la diminution de la vitesse de protéolyse en fonction du temps, du fait de la réduction de la quantité de protéines hydrolysables dans le jambon. Une fois complété et amélioré, le simulateur de procédé pourra aider les professionnels à tester des scénarios visant à réduire la quantité de sodium dans les jambons secs, sans altérer leur qualité finale

Progenitor cells in auricular cartilage demonstrate promising cartilage regenerative potential in 3D hydrogel culture

The reconstruction of auricular deformities is a very challenging surgical procedure that could benefit from a tissue engineering approach. Nevertheless, a major obstacle is presented by the acquisition of sufficient amounts of autologous cells to create a cartilage construct the size of the human ear. Extensively expanded chondrocytes are unable to retain their phenotype, while bone marrow-derived mesenchymal stromal cells (MSC) show endochondral terminal differentiation by formation of a calcified matrix. The identification of tissue-specific progenitor cells in auricular cartilage, which can be expanded to high numbers without loss of cartilage phenotype, has great prospects for cartilage regeneration of larger constructs. This study investigates the largely unexplored potential of auricular progenitor cells for cartilage tissue engineering in 3D hydrogels

Analyse d'image visibles et proche infrarouges : contributions à l'évaluation non-destructive du persillage dans la viande du boeuf

Le persillage (gras intramusculaire) dans la viande de boeuf est l'un des critères les plus importants pour l'évaluation de la qualité, notamment sa jutosité, dans les systèmes de classification de la viande. Le processus chimique, méthode destructive, est l'unique moyen officiellement utilisé pour évaluer la proportion du persillage dans la viande. C'est une méthode destructive, complexe et qui n'offre aucune information sur la distribution du persillage dans la viande. Cette thèse porte sur le développement d'une méthode originale destinée à l'évaluation non-destructive de la proportion volumétrique du persillage dans la viande du boeuf. Cette nouvelle méthode, qui pourrait être intégrée dans un système de vision artificielle (machine vision), est une première expérience pour ce genre d'application. À notre meilleure connaissance, aucune méthode semblable n'a été élaborée. De ces travaux de doctorat quatre contributions sont identifiées: la technique proposée, deux méthodes de segmentation d'images et une méthode non-destructive pour estimer la proportion volumétrique du persillage. La technique proposée permet d'avoir deux types d'images : une visible qui illustre la surface de la viande et une proche infrarouge qui est la projection orthogonale de l'échantillon de la viande (3D) en une image d'ombre (2D). Compte tenu de la complexité d'analyse des images, nous avons développé une méthode efficace de segmentation permettant d'identifier les régions homogènes les plus (ou les moins) claires dans une image à niveaux de gris. Cette méthode, qui est relativement générale, est basée sur un modèle mathématique permettant d'évaluer l'homogénéité des régions, qui lui-même a été introduit dans cette thèse. La généralisation de cette méthode pour la segmentation du persillage a démontré des résultats satisfaisants face aux objectifs attendus. Étant donné, que la forme volumétrique du persillage est aléatoire et que celle-ci dépend de la façon dont le persillage est déposé entre les fibres musculaires, ce qui est imprévisible, nous avons combiné les résultats de la segmentation de deux types d'images pour estimer le volume du persillage. L'intégration de l'ensemble des approches précédentes nous a permis de développer une nouvelle méthode non-destructive pour estimer la proportion volumétrique du persillage. Les résultats obtenus par la méthode proposée (non-destructive) ont été comparés aux résultats obtenus par une méthode chimique (destructive) comme étant la vérité-terrain (gold standard). Les résultats expérimentaux confirment les propriétés attendues de la méthode proposée et ils illustrent la qualité des résultats obtenus