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 /

Zinc-protoporphyrin content in commercial Parma hams is affected by proteolysis index and marbling

The contents of zinc-protoporphyrin (ZnPP) and heme in twenty-four sliced Parma hams made without the addition of curing agents were determined. Expressed on a dry weight basis, ZnPP averaged 45 mg/kg and ranged from 23 to 85 mg/kg. The heme content averaged 37 mg/kg on a dry matter basis and ranged from 17 to 73 mg/kg. A Principal Component Analysis (PCA) and Partial Least Squares (PLS) regression analyses were carried out to examine the existing correlations between these pigments and various physicochemical parameters in the final product. PCA showed the existence of associations between ZnPP, sensory redness and salt content. PLS suggests that the conversion of ZnPP from heme is facilitated in those hams with a higher proteolysis index and higher marbling.info:eu-repo/semantics/acceptedVersio

Assessing consumer preferences for labeling information of dry-cured serrano ham on a virtual supermarket in Spain

Encouraging healthy and personalized nutrition has become one of the EU strategic lines and, since 2015, the third sustainable developed objective promoted by the United Nations aims to ensure healthy lives and promote well-being for all ages. One approach to address this objective is to provide information to consumers through the labeling of food products. However, it has been scientifically proven that some food products provide an approximation of their nutrient content on the food packages, which might mislead consumers. Hence, this study examines consumers’ acceptance of precise nutrient labeling (nutritional facts and nutritional claims related to fat and salt content) on dry-cured ham (Jamón Serrano) in a virtual supermarket. The study was conducted in Zaragoza (Spain) on 161 consumers. In a virtual supermarket that mimics a real-life environment, participants were presented with a choice set of six alternatives and a no-buy option and were asked to choose their most preferred ham. The results indicate that Spanish consumers preferred dry-cured ham with a conventional nutrition label while the low salt content nutrition claim did not affect preferences

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 industry.info:eu-repo/semantics/acceptedVersio

Use and Understanding of Nutrition Labels: Impact of Diet Attachment

Food labels may have an important function in communicating nutrition information and have considerable potential to influence food choice and dietary behavior. Therefore, the aim of this study was to evaluate Spanish consumers’ reasons for reading or not reading nutrition information, their nutrition knowledge, perception and understanding of nutrition label information, and the possible impact of following a diet on all these. A 74-item questionnaire was developed to assess nutrition knowledge, attitude toward food labels, reasons for never reading nutrition information, food choice, the perceived importance of nutrition facts, and label-reading behavior. The results indicated that dietary patterns, nutrition knowledge, and sociodemographic characteristics strongly influenced label use. Based on the participants’ beliefs, four segments were identified for those who followed a diet and three segments for those who did not. Our study suggests that following a diet increases Spanish consumers’ nutrition knowledge as well as their use of nutrition labels, although this cause-effect relationship could be reversed. Nonetheless, further studies would be necessary to clarify the causal direction.info:eu-repo/semantics/publishedVersio

Formation of Zn-protoporphyrin during the elaboration process of non-nitrified serrano dry-cured hams and its relationship with lipolysis

This study assessed the ZnPP content, heme content, salt content, and instrumental color in the biceps femoris and semimembranosus muscles during the elaboration of Serrano dry-cured ham manufactured without the addition of nitrate and nitrite for 15 months. The effects of lipolysis and lipid oxidation on the content of Zn-protoporphyrin were also investigated in the biceps femoris. We found that the maximum formation of Zn-protoporphyrin occurred between end of resting and 6 months of processing, which coincides with temperature increase during processing and the end of salt equalization. Zn-protoporphyrin further increased in the biceps femoris until 9 months of processing but remained unchanged in the semimembranosus. Free fatty acid content increased till 6 months and then remained unchanged until the end of the process. These findings and those from an in vitro study reinforced the idea that the release of free fatty acids can promote the activity of the endogenous enzyme ferrochelatase and contribute to the formation of Zn-protoporphyrin from heme. However, the content of Zn-protoporphyrin decreased at the end of the processing, which may be due to the progression of lipid oxidation.info:eu-repo/semantics/acceptedVersio

Utilització de la tomografia computeritzada com a nova tecnologia per a la indústria del pernil curat

El pernil curat és un dels productes carnis més tradicionals del nostre país. Aquest producte té una elevada importància econòmica en el sector de la indústria alimentària —producció i consum. La tomografia computeritzada (TC) presenta un gran potencial com a eina per a l'optimització dels processos d'elaboració del pernil curat. Es tracta d'una tecnologia no destructiva que permet avaluar qualitativament la distribució de la sal durant tot el procés de fabricació.Dry-cured ham is one of themost traditional meat products in our country. This product has an enormous economic importance in the food industry sector —production and consume. Computed tomography (CT) has great potential as a tool for the optimization of dry-cured ham elaboration processes. This is a non-destructive technology that allows evaluating qualitatively the distribution of salt throughout the manufacturing process

Computed tomography and predictive microbiology for non-invasive evaluation of the impact of dry-cured ham production process conditions on the behaviour of Listeria monocytogenes and Clostridium botulinum

Variability of salt content in dry-cured ham production can pose microbiological food safety issues, especially in salt reduced and/or non-nitrified products. In this regard, computed tomography (CT) could help to non-invasively characterised the product to further adjust the production process and ensure its safety. The aim of this work was to study the application of CT to estimate aw in dry-cured ham to be used by predictive microbiology to evaluate the impact of the production process on the behaviour of Listeria monocytogenes and Clostridium botulinum. Effect of nitrite elimination and fat content of hams was also evaluated. Thirty hams with two different fat content levels were characterised analytically and using CT at different key points in the process. The safety of the process was evaluated by applying predictive microbiology using both analytical and CT data as model inputs. Results showed that nitrite and fat content had an impact on the predicted growth potential of the pathogens evaluated. After the resting period, if no nitrite is added, the time needed for 1 log increase (tinc) of L. monocytogenes would shorten by 26% and 22% in lean and fat hams, respectively. After week 12, important differences on tinc values for C. botulinum were found between both groups of hams (ca. 40% shorter in fat hams). CT can provide reliable pixel-to-pixel information for predictive microbiology to evaluate the growth of relevant pathogens, but further studies are needed to validate this combination as a tool to evaluate the safety of the production process.info:eu-repo/semantics/acceptedVersio