Escherichia (E.) coli O157:H7 survival in dry cured (uncooked) meat products leading to human illness outbreaks is an international problem. Their manufacture does not involve a heat kill step to ensure the destruction of the organism, and the adverse conditions created during processing may not be sufficient to prevent E. coli O157:H7 survival. Deodorized yellow mustard powder has antimicrobial properties from glucosinolate (sinalbin) hydrolysis catalyzed by the endogenous enzyme myrosinase, generating antimicrobial isothiocyanate (PHBIT). Previous work has shown that its addition during dry sausage manufacture was capable of eliminating the pathogen. In this study, its use for the same purpose was investigated during dry cured Westphalian ham production. Hams were inoculated with a 7.5 log cfu•g-1 cocktail of E. coli O157:H7, surface applied with 4% or 6% (w/w) deodorized yellow mustard powder, and monitored for E. coli O157:H7 survival during 80d ham maturation. One trial included the inoculation of Staphylococcus (S.) carnosus, a meat starter culture with myrosinase-like activity, onto the hams (after salt equilibration) to accelerate formation of antimicrobial isothiocyanate from mustard glucosinolate and help control the pathogen. In both trials, E. coli O157:H7 was reduced 3 log cfu•g-1 by 21d on hams treated with mustard powder, whereas only a 1 log cfu•g-1 reduction was found in the inoculated control which was not treated with mustard. By 45d, hams treated with mustard powder showed a reduction of >5 log cfu•g-1 E. coli O157:H7, whereas it took 80d to for numbers in control hams to be similarly reduced. Since a 5 log kill of E. coli O157:H7 was achieved in control hams by the end of 80d, dry cured Westphalian ham manufacture would be considered capable of controlling the risk of E. coli O157:H7 survival by North American regulatory agencies. However, deodorized yellow mustard powder at 4%, and to a greater extent at 6%, eliminated the pathogen at a significantly faster rate than the control during ham processing. Addition of the S. carnosus starter culture in trial 2 may have contributed to the maintenance of this effect through isothiocyanate formation. It also helped restore numbers of staphylococci, which were found to be sensitive to deodorized mustard powder.

Significant variability in cured leaf tobacco-specific nitrosamine (TSNA) content is commonly observed when sampling within dark air-curing barns. This variability may be due to inconsistency in the curing environment within different areas of the barn. A study was initiated in 2012 through support from a CORESTA Study Grant to evaluate if leaf TSNA content is related to microenvironmental conditions in the barn. Seed screened for low conversion of nicotine to nornicotine (sc) and high converter (HC) selections of TR Madole dark tobacco were cured in barns near Princeton and Lexington, Kentucky in 2012 and 2013. Temperature and relative humidity were measured with data loggers placed at 27 locations within each barn for the duration of curing. TSNA content was determined from 20-leaf samples collected from each selection at each of the 27 locations within each barn. There were no significant effects of individual data logger placement in either variety selection on hours above 24°C temperature, hours above 80% relative humidity, or TSNA; therefore, we investigated these data within 3-dimensional aspects of tier, room, and bent within each barn. There were various effects of tier, room, and bent on temperature, relative humidity, and TSNA; but limited significant relationships between temperature, relative humidity, and TSNA.

Escherichia (E.) coli O157:H7 survival in dry cured (uncooked) meat products leading to human illness outbreaks is an international problem. Their manufacture does not involve a heat kill step to ensure the destruction of the organism, and the adverse conditions created during processing may not be sufficient to prevent E. coli O157:H7 survival. Deodorized yellow mustard powder has antimicrobial properties from glucosinolate (sinalbin) hydrolysis catalyzed by the endogenous enzyme myrosinase, generating antimicrobial isothiocyanate (PHBIT). Previous work has shown that its addition during dry sausage manufacture was capable of eliminating the pathogen. In this study, its use for the same purpose was investigated during dry cured Westphalian ham production. Hams were inoculated with a 7.5 log cfu•g-1 cocktail of E. coli O157:H7, surface applied with 4% or 6% (w/w) deodorized yellow mustard powder, and monitored for E. coli O157:H7 survival during 80d ham maturation. One trial included the inoculation of Staphylococcus (S.) carnosus, a meat starter culture with myrosinase-like activity, onto the hams (after salt equilibration) to accelerate formation of antimicrobial isothiocyanate from mustard glucosinolate and help control the pathogen. In both trials, E. coli O157:H7 was reduced 3 log cfu•g-1 by 21d on hams treated with mustard powder, whereas only a 1 log cfu•g-1 reduction was found in the inoculated control which was not treated with mustard. By 45d, hams treated with mustard powder showed a reduction of >5 log cfu•g-1 E. coli O157:H7, whereas it took 80d to for numbers in control hams to be similarly reduced. Since a 5 log kill of E. coli O157:H7 was achieved in control hams by the end of 80d, dry cured Westphalian ham manufacture would be considered capable of controlling the risk of E. coli O157:H7 survival by North American regulatory agencies. However, deodorized yellow mustard powder at 4%, and to a greater extent at 6%, eliminated the pathogen at a significantly faster rate than the control during ham processing. Addition of the S. carnosus starter culture in trial 2 may have contributed to the maintenance of this effect through isothiocyanate formation. It also helped restore numbers of staphylococci, which were found to be sensitive to deodorized mustard powder.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2004. / Härtill 6 uppsatser.

Doctor of Philosophy / Department of Entomology / Thomas W. Phillips / The phase-out of methyl bromide production, the most effective fumigant for the control of the ham mite, Tyrophagus putrescentiae (Schrank) (Acari: Acaridae), on dry-cured ham has necessitated the search for other management methods. The foundation of a successful management program is an effective monitoring program that provides information on pest presence and abundance over time and space to help in making management decisions. By using the standard trap made from disposable Petri dishes and a dog food-based bait, mite activity was monitored weekly in five dry-cured ham aging rooms from three commercial processing facilities from June 2012 to September 2013. Results indicated that mite numbers in traps in facilities typically had a pattern of sharp decline after fumigation, followed by a steady increase until the next fumigation. Average trap captures varied due to trap location, indicating that traps could be used to identify locations where mite infestation of hams may be more likely to occur. Experiments were also conducted in 6 m x 3 m climate-controlled rooms to determine the effects of some physical factors on trap capture. Factors such as trap design, trap location, trap distance, duration of trapping, and light conditions had significant effects on mite capture. Mites also responded differently to light emitting diodes of different wavelengths, either as a component of the standard trap or as a stand-alone stimulus to orientation. To determine the relationship between trap capture and mite density, experiments were carried out in the climate-controlled rooms. Mite density was varied but trap number remained constant for all mite densities. There was strong positive correlation between trap capture and mite density. In simulated ham aging rooms, the distribution of mites on hams was determined and different sampling techniques such as vacuum sampling, trapping, rack sampling, ham sampling and absolute mite counts from whole hams were compared and correlated. Results showed weak or moderate correlations between sampling techniques in pairwise comparisons. Two sampling plans were developed to determine the number of samples required to estimate mite density on ham with respect to fixed precision levels or to an action threshold for making pest management decisions. Findings reported here can help in the optimization of trapping and sampling of ham mite populations to help in the development of efficient, cost-effective tools for pest management decisions incorporated with alternatives to methyl bromide.

Orientador: Pedro Eduardo de Felicio, Expedito Tadeu Facco Silveira / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-04T13:59:07Z (GMT). No. of bitstreams: 1 BergaminFilho_Walter_M.pdf: 465962 bytes, checksum: 7133c03c01d649f1e25c78b4b0f9e052 (MD5) Previous issue date: 2005 / Resumo: A metodologia de elaboração de presunto cru proposta neste trabalho foi planejada com base na combinação de desossa, adição de transglutaminase, massageamento e moldagem das peças previamente à secagem e maturação. Analisaram-se os efeitos de dois teores de NaCl adicionado (3,5% e 5% do peso da carne) nas propriedades físico-químicas do produto final, como Aw, teor de cloretos (NaCl%) e de umidade, e perda de peso. Como nos processos tradicionais, fez-se a salga seca utilizando nitrato de sódio, nitrito de sódio e sal grosso comercial tipo I. As médias de temperatura (T) e umidade relativa (UR) desta etapa ficaram em torno de 2,5 ± 1,31ºC e 83 ± 2,75%, respectivamente. Já na etapa de secagem, houve redução da UR média para 71,62 ± 1,75% e aumento da T média para 4,5 ± 0,85ºC. Na maturação, as temperaturas foram acrescidas de 1ºC a cada nove (ou sete) dias, até atingir 16ºC, enquanto a UR foi mantida em ±70%. Ao final do processo, os presuntos crus apresentaram as seguintes características físico-químicas: Aw no centro da peça de 0,900 e 0,905, para os tratamentos 3,5% e 5% de sal, respectivamente; para os teores de umidade, não houve diferença significativa, porém, o tratamento 5% apresentou um valor de 53,04 ± 2,37%, superior ao do tratamento 3,5%, que foi de 48,65 ± 2,76%. Este último parâmetro é conseqüência da perda de peso dos presuntos durante todo o processo, que foi significativamente maior no tratamento 3,5%, atingindo 39,74 ± 4,02%, contra os 37,22 ± 2,96% do tratamento 5%. O curto período de maturação e as temperaturas amenas durante esta fase, retardaram a ação enzimática responsável pela hidrólise de aminoácidos, provocando a queda do pH final, que atingiu valores de 5,60 e 5,56 para os tratamentos 3,5 e 5% de sal, respectivamente. Quanto às características microbiológicas, ambos os tratamentos estavam de acordo com a legislação vigente no país. Os presuntos crus obtidos no término do processo apresentaram formato e espessura apropriados para o fatiamento, excelente aparência, aroma característico e principalmente, um sabor muito próximo ao dos presuntos crus tradicionais encontrados no mercado brasileiro / Abstract: The methodology proposed to produce the dry-cured ham in this work was based on a technology combining bonning, transglutaminase application, tumbling and molding. It was evaluated the effects of two levels of NaCl added for fresh meat (3.5 and 5%) on the physicochemical characteristics of the final products such as water activity (Aw), chloride content (NaCl%) and weight loss. Similar to the traditional processing of dry cured hams, salting was carried out using dry cure, combining NaCl, sodium nitrate and sodium nitrite. The average temperature (T) and relative humidity (RH) in this phase were 2,5 ± 1,31ºC and 83 ± 2,75%, respectively. In the drying period, the average RH was reduced to 71,62 ± 1,75% and average T was increased up to 4,5 ± 0,85ºC. During the ageing, the T was increased gradually 1ºC each nine (or seven) days up to 16ºC, while the RH was fixed to ± 70%. At the end of the processing time, the dry cured hams presented: Aw values 0.900 and 0.905, measured in the inner part of the product for the treatments 3.5% and 5%, respectively. Treatment 5% presented higher values (53.04 ± 2.37%) of moisture than the 3.5% (48.65 ± 2.76%). This last parameter was a consequence of the weight loss during the processing time, that where higher in the treatment 3.5% (39.74 ± 4.02%) than the 5% (37.22 ± 2.96%). The mild temperatures during the short ageing time have possibly decreased the amino acids hydrolysis, and this the probable cause of the final pH, which were 5.60 and 5.56 for the treatments 3.5 and 5%, respectively. In the microbiological counts, both treatments satisfy the Brazilian current legislation requirement. The dry cured hams at the end of the processing presented shape and thickness appropriate to slicing, excellent appearance, characteristic aroma, and mainly, similar flavor to the traditional dry cured hams found in the Brazilian market / Mestrado / Tecnologia de Alimentos / Mestre em Tecnologia de Alimentos

No description available.

This research project was divided into three parts. In the first part, heme, nonheme, and total iron methodologies for meats were evaluated. The accuracy, precision, and specificity of each method were determined by spike recoveries of heme and nonheme iron, and by analysis of National Institute of Science and Technology standard reference materials. The most reliable and practical methods were then used to determine the total, nonheme, and heme iron contents of various meats before and after cooking. The meats analyzed were beef, pork, lamb, chicken, and turkey. The wet-ashing technique was a novel procedure in which nitric acid was used to digest most of the solids followed by peroxy-monosulfuric acid to complete the digestion. Total iron values of the meats were consistent with those previously reported, but the percentage of heme iron in red meats was much greater than commonly assumed, both before and after cooking. In the second part, the distribution of heme and total iron in heat-processed poultry products was investigated using light and dark chicken meat in the form of deep-flied chicken breasts and legs purchased from fast food restaurants and grocery stores in a ready-to-eat condition. Heme and total iron values were 1.7 ± 0.5 and 6.5 ± 2.0 μg Fe/g meat for light chicken meat and 7.6 ± 1.6 and 19.3 ± 2.2 μg Fe/g for dark chicken meat. Percent heme iron values averaged 29 and 40% for light and dark chicken meat, respectively. In the third and final part, an application for the heme and nonheme iron data assembled above was developed to give dieticians an important tool in dietary formulations designed to maintain iron homeostasis. From the data it is evident that cooked light chicken meat, taken from the breast, would provide the lowest quantity of absorbable iron among the meats investigated and that ground beef, highest in heme iron, would provide the greatest quantity of bioavailable iron. Additional research was performed on processed beef products. Cooked ground beef, frankfurters, beef steak, and roast beef were analyzed for heme and total iron. The different beef products contained similar amounts of total iron, 31.4 to 34.2 μg/g, but the heme iron content ranged from 6.2 μg/g in frankfurters to 36.3 μg/g in beef steak. Percent heme iron ranged from 33.0 to 63.8% in all meats. Total iron, heme iron, and percent heme iron varied significantly (P < 0.01) among meats, sources, and preparations. This research was published and has been reproduced in Appendix F.

Tyrophagus putrescentiae (Schrank) (Sarcoptiformes: Acaridae), also known as the ham mite, may infest dry cured hams during the aging process. The fumigant methyl bromide is currently used to control mite infestations, but eventually will not be available for use since it contributes to the depletion of the ozone layer. The use of ham nets treated with xanthan gum, carrageenan, propylene glycol alginate, propylene glycol (PG), and lard were evaluated for their impact on mite orientation to or oviposition on treated or untreated ham cubes, mite reproduction and population growth over a 10-week period. When nets were infused with gum and PG, behavioral tests indicated that greater than 95% of the mites oriented to the ham cubes that were wrapped in untreated nets when compared to treated nets and no eggs were laid on the latter. The reproduction assays indicated that there were fewer (P < 0.05) T. putrescentiae produced over a two-week period on ham cubes covered with both gum and PG treated nets when compared to the untreated or gum-only treated nets over the 10-week storage period of the experiment. Medium and high concentrations of PG treatments had the lowest mite reproduction rates. No more than four mites could be found on each of these treatments in comparison to 200-300 mites that were on the untreated ham cubes. When nets were infused with gum, PG, and lard, behavioral tests indicated that fewer mites oriented to the ham cubes that were wrapped with gum, lard, and medium PG than those with untreated nets. The oviposition assays revealed that on average less than three eggs were laid on the ham cubes with treated nets in comparison to 69-165 eggs on the untreated ham cubes. Reproduction assays demonstrated that fewer T. putrescentiae (P < 0.05) were on ham cubes with treated nets containing PG when compared to the number of mites on ham cubes with untreated nets over 10 weeks of storage. Lard infused nets without PG did not decrease the mite population (P > 0.05). The net without coating slowed the growth and reproduction of T. putrescentiae since net controls had fewer mites (P < 0.05) than controls without nets. With a few exceptions, fungi were not present on ham cubes that were treated with PG-containing nets over 10 weeks of storage. This research demonstrated the efficacy of using nets treated with food-grade ingredients during ham aging to control mite infestations on a laboratory scale. Further research will be conducted to determine the effectiveness of the same treated nets on whole hams in commercial aging rooms.

Tesis por compendio / [EN] Dry-cured ham is a product highly appreciated by consumers, nevertheless, there are a large number of manufacturing process-related parameters, as well as ham intrinsic factors, that compromise its final quality. One of the main problems in the quality of dry-cured ham is the appearance of textural defects, in particular, the development of pastiness. This defect is characterized by an excessive softness and loss of elastic behavior of the ham and when tasted, it provokes a feeling similar to the mouth-coating sensation produced by a flour-water paste during the mastication process. Pastiness also makes slicing difficult and promotes the adhesiveness between slices. Currently, the methods available to measure ham pastiness are time-consuming and destructive. For this reason, the seek of faster and non-destructive technologies capable of detecting pastiness is of great importance. In this sense, different technologies such as near infrared spectroscopy, X-rays or ultrasound, that have been previously tested for the nondestructive characterization of different meat products, could be of interest for the detection of ham pastiness. Different approaches, such as the use of high hydrostatic pressure (HHP) or the application of low-temperature long-time thermal treatments (LTLT) at the end of the ham manufacturing, have been previously addressed for the correction of pastiness in dry-cured ham. Notwithstanding, the high cost and the long time required for the HHP and LTLT treatments, respectively, highlights the need for moderate cost and faster alternatives. In this context, the main goals of this thesis were to determine the feasibility of using low intensity ultrasound to non-destructively detect the appearance of pastiness during ham manufacturing and to characterize the level of pastiness in the final product, as well as to explore the feasibility of mild ultrasonic assisted thermal treatments to correct this textural defect. To meet the goal of ham pastiness characterization and correction, a customized drycured ham manufacturing was designed and carried out in order to obtain hams with different levels of pastiness with no remarkable differences on the salt content. During ham manufacturing, the feasibility of using contact ultrasound to monitor the appearance of pastiness was addressed. The ultrasonic velocity was measured in the raw ham, at the end of the salting and post-salting stages, 3 times during the drying-maturation and once the manufacturing was finished. At the end of the manufacturing, the pastiness level (high, medium and no pasty) was also sensory evaluated by an expert panel. As the manufacturing progressed, a progressive increase in the ultrasonic velocity, from 1536 m/s in the raw ham to 1713 m/s in the final dry-cured ham, was found. Notwithstanding, the increase in the ultrasonic velocity was not related with the pastiness defect, probably because the ham texture changes linked to pastiness were masked by the great influence of the compositional changes (salt gain and moisture loss) on the ultrasonic velocity. Therefore, the ultrasonic velocity was not an effective parameter to detect the appearance of pastiness in hams during manufacturing, neither to classify them according to its pastiness level at the end of the manufacturing. Contact ultrasound was also used to monitor the compositional and textural changes taking place along the ham post-salting stage. For this purpose, another batch of hams was salted and post-salting times from 7 to 56 days were tested. During post-salting, the hams were weighted and the ultrasonic velocity was measured every 2 days. Each 7 post-salting days, the composition and the textural properties of a different ham were destructively analyzed. The ham weight loss during the post-salting stage was satisfactorily (r=0.95) described by the increase in the ultrasonic velocity. Moreover, the salt distribution and the moisture loss in the internal parts of the ham were satisfactorily related (r=0.93 and r=0.86, respectively) with the increase in the ultrasonic velocity. The variation in the ham hardness during post-salting was negligible and hence, the velocity increase was mainly attributed to the compositional changes, being barely affected by the changes in texture. The hams obtained after the customized manufacturing were sliced and the ultrasonic velocity and attenuation were measured on the Biceps femoris muscle with the aim of nondestructively finding out its pastiness level. Furthermore, in order to better analyze this textural defect, the composition, protein degradation, instrumental texture and microstructure of the hams were analyzed. Pasty samples presented the highest proteolysis index (38.7% compared to 33.1% for non-pasty hams), exhibited the more relevant structural degradation (merged myofibril structures and appearance of large gaps) and consequently, were the softest (5.4 N of hardness compared to 16.7 N for non-pasty hams) and presented the most intense viscous behavior (0.434 compared to 0.372 for non-pasty hams), although a high degree of experimental variability was found. The non-destructive assessment performed with ultrasound revealed that ultrasonic attenuation could be successfully applied for the grading of dry-cured ham slices according to its pastiness level. Thus, the greater the pastiness, the higher the ultrasonic attenuation, being the average attenuation coefficient for high, medium and no-pasty samples 48.2, 45.4 and 43.1 Np/m, respectively. Notwithstanding, the ultrasonic velocity was similar in all the ham samples, regardless its pastiness level. As observed in whole hams, the ultrasonic velocity was not a satisfactory parameter to detect pastiness in sliced ham, since the large influence of the composition on the ultrasonic velocity added to a similar salt and moisture content of the samples, regardless its pastiness level, led to a similar velocity for the different pastiness levels. Air-coupled ultrasonic techniques in both through-transmission and pulse-echo modes were developed for the characterization of dry-cured ham texture. The non-invasive nature of aircoupled ultrasound allows a contactless measurement, which makes easier its industrial implementation compared to conventional ultrasound techniques for high speed applications without material surface alteration and cross-contamination between food items. As for corrective actions of the texture defects in dry-cured ham, mild thermal treatments in two different heating media (water and air) were evaluated. Furthermore, the feasibility of intensifying these mild thermal treatments with the assistance of power ultrasound was considered. For that purpose, commercial vacuum-packed dry-cured ham slices were heated in a liquid medium, with and without ultrasonic assistance, at different temperatures (40, 45 and 50 ºC), measuring the temperature in the Biceps femoris and in the Semimembranosus muscles. Regarding the treatments in air, commercial vacuum-packed dry-cured ham cylinders were used. In the first set of experiments, ham was heated at a constant air velocity (2 m/s) until different temperatures (40, 45 and 50 ºC) were reached. While in the second set of experiments, ham was treated at constant air temperature (50 ºC) at different air velocities (1, 2, 3, 4 and 6 m/s). In both sets, the treatments were performed with and without power ultrasound application, measuring the temperature in the center of the cylinder. Thermal treatments were extended until a target temperature of 5 ºC lower than the medium (water-air) heating temperature was reached, thus, holding temperature stage did not exist and the treatments only considered the heating one. The heating kinetics of the ham treated in both water and air heating media were mathematically described by means of a heat conduction model. Once the heating finalized, the textural changes of ham (hardness and elastic behavior) were evaluated. The experiments showed that power ultrasound application sped up the heat transfer, significantly (p<0.05) shortening the heating time and increasing the apparent thermal diffusivity up to 51 and 37% for water and air heat treatments, respectively. For the thermal treatments using water, the increase in temperature during the heating brought about a lower ultrasonic intensification (the apparent thermal diffusivity was increased by 51% at 40 ºC compared to the 21% at 50 ºC). On the contrary, in experiments with air, the higher the temperature, the greater the ultrasonic enhancement (the apparent thermal diffusivity was increased by 5% at 40 ºC compared to the 38% at 50 ºC). The effect of the ultrasound application decreased as the air velocity increased, being minimal when the air velocity was the highest (the apparent thermal diffusivity was increased by 21% at 1 m/s compared to the 5% at 6 m/s). As regards the changes in the textural properties of ham after the mild thermal treatments at short times, an increase in hardness and elastic behavior was observed. Finally, the texture correction in dry-cured ham with different levels of pastiness was tackled. For this purpose, vacuum-packed dry-cured ham slices with high, medium and no pastiness were heated in a liquid medium at 40 and 50 ºC for a longer time (5 h, including heating and holding stages) than heating experiments, with and without the assistance of power ultrasound during the heating phase. The texture (hardness, elastic behavior and adhesiveness) and the microstructure of the ham was evaluated in both treated and control samples. After the mild thermal treatments, the texture of ham was improved since the hardness was increased (102%) and the viscous behavior diminished (11%). On average, the increase of hardness at 50 ºC was 159% higher than at 40 ºC, while the decrease of the viscous behavior was 13.5% larger at 50 ºC compared to 40 ºC. The ham adhesiveness was also enhanced independently of the treatment temperature, with a 55% reduction being observed. The application of power ultrasound during the heating phase did not involve any additional textural change. Likewise, after the thermal treatments, the microstructure of hams with pastiness notably changed, experiencing a severe shrinkage of the myofibrils, which contributed to explain the reported textural changes. In conclusion, pastiness is a relevant and highly complex textural defect in dry-cured ham. The use of contact ultrasound and the measurement of the ultrasonic attenuation could be considered a potential technology to non-destructively detect and characterize pastiness in sliced dry-cured ham. Future work should focus on extending this approach to identify pasty whole hams, considering for this purpose the use of air-coupled ultrasound. Moreover, the use of mild thermal treatments in liquid or gas media could be a feasible method to correct the defective texture of dry-cured hams and the application of power ultrasound during the heating phase could be a relevant means of speeding up the thermal treatments. / [ES] El jamón curado es un producto muy apreciado por los consumidores, sin embargo, existen numerosos parámetros relacionados con el procesado, así como factores intrínsecos del jamón, que comprometen su calidad final. Uno de los principales problemas de calidad del jamón curado es la aparición de defectos de textura, concretamente, el desarrollo de pastosidad. Este defecto se caracteriza por una textura excesivamente blanda y un comportamiento menos elástico del jamón. A nivel sensorial, provoca una sensación de recubrimiento en boca similar a la masticación de una pasta de harina y agua. La pastosidad también dificulta el loncheado y promueve la adhesividad entre lonchas. Actualmente, los métodos disponibles para caracterizar la pastosidad requieren mucho tiempo y son destructivos. Por esta razón, la búsqueda de tecnologías más rápidas y no destructivas capaces de detectar la pastosidad es de gran importancia. En este sentido, distintas tecnologías como espectroscopía de infrarrojo cercano, rayos-X o ultrasonidos, que han sido ensayadas previamente para la caracterización no destructiva de diferentes productos cárnicos, podrían ser de interés para la detección de pastosidad en jamón. Diferentes alternativas, como el uso de altas presiones hidrostáticas (HHP) o la aplicación de tratamientos térmicos de larga duración a baja temperatura (LTLT) al final del proceso de elaboración del jamón, han sido abordadas previamente para la corrección de pastosidad en jamón curado. Sin embargo, el elevado coste y el largo tiempo requerido para los tratamientos HHP y LTLT, respectivamente, pone de manifiesto la necesidad de encontrar alternativas con un coste moderado y más rápidas. En este contexto, los principales objetivos de esta tesis fueron determinar la viabilidad de la utilización de ultrasonidos de baja intensidad para detectar de manera no destructiva la aparición de pastosidad durante el proceso de elaboración de jamón curado y caracterizar el nivel de pastosidad en el producto final, así como explorar la viabilidad de tratamientos térmicos moderados asistidos por ultrasonidos de alta intensidad para corregir dicho defecto de textura. Para cumplir el objetivo de caracterizar y corregir el defecto de pastosidad en jamón, se diseñó y se llevó a cabo un proceso de elaboración para obtener jamones con distintos niveles de pastosidad sin diferencias considerables del contenido en sal. Durante el procesado, se abordó la viabilidad de utilizar ultrasonidos por contacto para monitorizar la aparición de la pastosidad. Así, la velocidad ultrasónica se midió en el jamón fresco, al final de las etapas de salado y postsalado, 3 veces durante el secado-maduración y una vez terminado el proceso de elaboración. Al final del procesado, también se evaluó el nivel de pastosidad (alto, medio y sin pastosidad) en el jamón loncheado por un panel experto. A medida que avanzó el proceso de elaboración, se observó un aumento progresivo de la velocidad ultrasónica, de 1536 m/s en jamón fresco hasta 1713 m/s en jamón curado. Sin embargo, el aumento en la velocidad ultrasónica no se relacionó con el defecto de pastosidad, probablemente porque los cambios de textura del jamón vinculados con la pastosidad fueron enmascarados por la gran influencia de los cambios composicionales (ganancia de sal y pérdida de humedad) en la velocidad ultrasónica. Así, la velocidad ultrasónica no fue un parámetro útil para detectar la aparición de pastosidad en jamón durante su procesado ni para clasificar los jamones según su nivel de pastosidad al final del procesado. Los ultrasonidos por contacto también se utilizaron para monitorizar los cambios composicionales y texturales que tienen lugar a lo largo de la etapa de postsalado del jamón. Para ello, se saló otro lote de jamones y se evaluaron distintos tiempos de postsalado, desde 7 hasta 56 días. Durante el postsalado, los jamones se pesaron y se midió su velocidad ultrasónica cada 2 días. Cada 7 días de postsalado, se analizó destructivamente la composición y las propiedades texturales de un jamón. La pérdida de peso de los jamones durante la etapa de postsalado fue descrita satisfactoriamente (r=0.95) por el aumento de la velocidad ultrasónica. Además, la distribución de sal y la pérdida de humedad en el interior del jamón se relacionaron de forma satisfactoria (r=0.93 y r=0.86, respectivamente) con el aumento de la velocidad ultrasónica. La variación en la dureza del jamón durante el postsalado fue no significativa y, por ello, el aumento de la velocidad ultrasónica se atribuyó principalmente a los cambios de composición, siendo apenas afectada por los cambios de textura. Los jamones obtenidos con distintos niveles de pastosidad después del proceso de elaboración, se cortaron y se midió la velocidad y la atenuación ultrasónica del músculo Biceps femoris con el objetivo de averiguar de forma no destructiva su nivel de pastosidad. Además, con el fin de analizar mejor este defecto de textura, se analizaron el índice de proteólisis, la microestructura, la textura instrumental y la composición de los jamones. Las muestras pastosas presentaron el índice de proteólisis más alto (38.7% comparado con el 33.1% de los jamones no pastosos), mostraron la degradación estructural más relevante (estructuras miofibrilares fusionadas y aparición de grandes huecos) y, en consecuencia, fueron las más blandas (5.4 N de dureza en comparación con los 16.7 N de los jamones no pastosos) y presentaron el comportamiento viscoso más intenso (0.434 comparado con el 0.372 de los jamones no pastosos), aunque se encontró una gran variabilidad experimental. La evaluación no destructiva llevada a cabo mediante ultrasonidos reveló que la atenuación ultrasónica se podría aplicar con éxito para la clasificación de las lonchas de jamón curado según su nivel de pastosidad. Así, cuanto mayor fue la pastosidad, mayor fue la atenuación ultrasónica, siendo el coeficiente de atenuación promedio de las muestras con alta, media y sin pastosidad de 48.2, 45.4 y 43.1 Np/m, respectivamente. Sin embargo, la velocidad ultrasónica fue muy similar en todas las muestras de jamón, independientemente de su nivel de pastosidad. Como se observó en los jamones enteros, la velocidad ultrasónica no fue un parámetro útil para cuantificar el defecto de pastosidad en jamón loncheado, ya que la gran influencia de la composición en la velocidad ultrasónica sumada al contenido similar de sal y humedad de las muestras, independientemente de su nivel de pastosidad, dio lugar a una velocidad similar en todos los niveles de pastosidad. Se desarrollaron dos técnicas de ultrasonidos acoplados por aire, tanto en modo transmisión-recepción como en pulso-eco, para caracterizar la textura de jamón curado. El carácter no invasivo de los ultrasonidos acoplados por aire permite llevar a cabo medidas sin contacto, facilitando su aplicación a nivel industrial en comparación con las técnicas ultrasónicas convencionales, ya que pueden realizarse medidas a mayor velocidad, sin alterar la superficie del material y evitando la contaminación cruzada entre alimentos. En cuanto a las medidas de corrección de defectos texturales en jamón curado, se evaluaron tratamientos térmicos moderados en dos medios de calentamiento diferentes (agua y aire). Además, se consideró la viabilidad de intensificar dichos tratamientos mediante la aplicación de ultrasonidos de alta intensidad (o de potencia). Para ello, se calentaron lonchas de jamón curado comercial envasadas al vacío en medio líquido, con y sin la aplicación de ultrasonidos, a diferentes temperaturas (40, 45 y 50 ºC), midiendo la temperatura en los músculos Biceps femoris y Semimembranosus. Respecto a los tratamientos en aire, se utilizaron cilindros de jamón curado comercial envasado al vacío. En el primer set de experimentos, el jamón se calentó a velocidad de aire constante (2 m/s) a diferentes temperaturas (40, 45 y 50 ºC); mientras que, en el segundo experimento, el jamón se calentó a temperatura de aire constante (50 ºC) a distintas velocidades (1, 2, 3, 4 y 6 m/s). En los dos sets, los tratamientos se llevaron a cabo con y sin la aplicación de ultrasonidos de potencia, midiendo la temperatura en el centro del cilindro. Los tratamientos térmicos se prolongaron hasta alcanzar la temperatura objetivo, definida como 5 ºC por debajo de la temperatura del medio de calentamiento (agua o aire). Así, no se llevó a cabo una fase de mantenimiento de la temperatura y sólo se consideró la fase de calentamiento de los tratamientos térmicos. Las cinéticas de calentamiento del jamón tratado tanto en agua como en aire se describieron matemáticamente considerando que la transferencia de calor estuvo únicamente controlada por conducción. Una vez finalizado el calentamiento, se evaluaron los cambios texturales del jamón (dureza y comportamiento elástico). Los experimentos mostraron que la aplicación de ultrasonidos de potencia aceleró la transferencia de calor, reduciendo significativamente (p<0.05) el tiempo de calentamiento y aumentando la difusividad térmica aparente hasta un 51 y 37% en los tratamientos térmicos en agua y aire, respectivamente. En el caso de los tratamientos térmicos en agua, el aumento de la temperatura durante el calentamiento provocó una intensificación ultrasónica menor (la difusividad térmica aparente aumentó un 51% a 40 ºC comparado con el 21% a 50 ºC). Por el contrario, en las experiencias en aire, cuanto mayor fue la temperatura, más efectiva fue la aplicación de los ultrasonidos (la difusividad térmica aparente incrementó un 5% a 40 ºC comparado con el 38% a 50 ºC). El efecto de la aplicación de los ultrasonidos disminuyó con el aumento de la velocidad del aire, siendo mínimo con la velocidad de aire más alta ensayada (la difusividad térmica aparente aumentó un 21% a 1 m/s comparado con el 5% a 6 m/s). En cuanto a los cambios de las propiedades texturales del jamón después de los tratamientos térmicos moderados limitados a la fase de calentamiento, se observó un aumento en su dureza y en su comportamiento elástico. Por último, se abordó la corrección de textura en jamón curado con distintos niveles de pastosidad. Para ello, se calentaron lonchas de jamón con alta, media y sin pastosidad envasadas al vacío en medio líquido a 40 y 50 ºC durante tiempos más largos (5 h, incluyendo las fases de calentamiento y mantenimiento) que en las experiencias sólo de calentamiento, con y sin la aplicación de ultrasonidos de potencia únicamente durante la fase de calentamiento. La textura (dureza, comportamiento elástico y adhesividad) y la microestructura del jamón se evaluaron tanto en las muestras tratadas como en las control. Después de los tratamientos térmicos moderados, la textura del jamón se vio mejorada puesto que su dureza aumentó (102%) y su comportamiento viscoso disminuyó (11%). En promedio, el aumento de la dureza a 50 ºC fue un 159% mayor que a 40 ºC, mientras que la disminución del comportamiento viscoso fue un 13.5% mayor a 50 ºC que a 40 ºC. La adhesividad del jamón también se vio disminuida, independientemente de la temperatura de tratamiento, observándose una reducción media del 55%. La aplicación de ultrasonidos de potencia durante la fase de calentamiento no implicó ningún cambio textural adicional. Asimismo, después de los tratamientos térmicos, la microestructura de los jamones con alta pastosidad cambió notablemente, experimentando una severa contracción de las miofibrillas, lo cual contribuyó a explicar los cambios de textura mencionados. En conclusión, la pastosidad es un defecto textural relevante y muy complejo en jamón curado. El uso de ultrasonidos por contacto y la medida de la atenuación ultrasónica podría considerarse a nivel industrial para detectar y caracterizar de forma no destructiva la pastosidad en lonchas de jamón curado. Futuros trabajos deberían estar orientados a la aplicación de esta tecnología para la identificación de jamones pastosos enteros, considerando para ello el uso de ultrasonidos acoplados por aire. Además, el uso de tratamientos térmicos moderados en medio líquido o gaseoso podría ser un método viable para corregir la textura defectuosa de jamones curados y la aplicación de ultrasonidos de potencia durante la fase de calentamiento podría considerarse para acelerar los tratamientos térmicos. / [CA] El pernil curat és un producte molt apreciat pels consumidors, no obstant això, existeixen nombrosos paràmetres relacionats amb el processament, així com factors intrínsecs del pernil, que comprometen la seua qualitat final. Un dels principals problemes de qualitat del pernil curat és l'aparició de defectes de textura, concretament, el desenvolupament de pastositat. Aquest defecte es caracteritza per una excessiva blanor i una pèrdua del comportament elàstic del pernil. A nivell sensorial, provoca una sensació de recobriment en boca similar a la masticació d'una pasta de farina i aigua. La pastositat també dificulta el tallat i promou l'adhesivitat entre rodanxes. Actualment, els mètodes disponibles per a mesurar la pastositat requereixen molt de temps i són destructius. Per aquesta raó, la cerca de tecnologies més ràpides i no destructives capaces de detectar la pastositat és de gran importància. En aquest sentit, diferents tecnologies com espectroscòpia d'infraroig pròxim, raigs-X o ultrasons, que han sigut assajades prèviament per a la caracterització no destructiva de diferents productes carnis, podrien ser d'interés per a la detecció de pastositat en pernil. Diferents alternatives, com l'ús d'altes pressions hidroestàtiques (HHP) o l'aplicació de tractaments tèrmics de llarga duració a baixa temperatura (LTLT) al final del procés d'elaboració del pernil, han sigut abordades prèviament per a la correcció de pastositat en pernil curat. No obstant això, l'elevat cost i el llarg temps requerit per als tractaments HHP i LTLT, respectivament, posa de manifest la necessitat de trobar alternatives amb un cost moderat i més ràpides. En aquest context, els principals objectius d'aquesta tesi van ser determinar la viabilitat de la utilització dels ultrasons de baixa intensità per a detectar de manera no destructiva l'aparició de pastositat durant el procés d’elaboració de pernil curat i caracteritzar el nivell de pastositat en el producte final, així com explorar la viabilitat de tractaments tèrmics moderats assistits per ultrasons d’alta intensitat per a corregir aquest defecte de textura. Per a complir l'objectiu de caracteritzar i corregir el defecte de pastositat en pernil, es va dissenyar i es va dur a terme un procés d'elaboració configurat per a obtindre pernils amb diferents nivells de pastositat sense diferències considerables del contingut en sal. Durant el processament, es va abordar la viabilitat d'utilitzar ultrasons per contacte per a monitorar l'aparició de pastositat. La velocitat ultrasònica es va mesurar en el pernil fresc, al final de les etapes de salat i postsalat, 3 vegades durant l'assecat-maduració i una vegada acabat el procés d'elaboració. Al final del processament, el nivell de pastositat (alta, mitjana i sense pastositat) també es va avaluar per un panell expert. A mesura que va avançar el procés d'elaboració, es va trobar un augment progressiu de la velocitat ultrasònica, anant des de 1536 m/s en pernil fresc fins a 1713 m/s en pernil curat. No obstant això, l'augment en la velocitat ultrasònica no es va relacionar amb el defecte de pastositat, probablement perquè els canvis de textura del pernil vinculats amb la pastositat van ser emmascarats per la gran influència dels canvis composicionals (guany de sal i pèrdua d'humitat) en la velocitat ultrasònica. Així, la velocitat ultrasònica no va ser un paràmetre efectiu per a detectar l'aparició de pastositat en pernil durant el seu processament ni per a classificar els pernils segons el seu nivell de pastositat al final del processament. Els ultrasons per contacte també es van utilitzar per a monitorar els canvis composicionals i texturals que tenen lloc al llarg de l'etapa de postsalat del pernil. Per a això, es va salar un altre lot de pernils i es van avaluar diferents temps de postsalat, des de 7 fins a 56 dies. Durant el postsalat, els pernils es van pesar i es va mesurar la seua velocitat ultrasònica cada 2 dies. Cada 7 dies de postsalat, es van analitzar destructivament la composició i les propietats texturals d'un pernil diferent. La pèrdua de pes dels pernils durant l'etapa de postsalat va ser descrita satisfactòriament (r=0.95) per l'augment de la velocitat ultrasònica. A més, la distribució de sal i la pèrdua d'humitat a l'interior del pernil es van relacionar de manera satisfactòria (r=0.93 i r=0.86, respectivament) amb l'augment de la velocitat ultrasònica. La variació en la duresa del pernil durant el postsalat va ser mínima i, per això, l'augment de la velocitat ultrasònica es va atribuir principalment als canvis de composició, sent a penes afectada pels canvis de textura. Els pernils obtinguts després del procés d'elaboració configurat per a obtindre pernils amb diferents nivells de pastositat, es van tallar i es va mesurar la velocitat i l'atenuació ultrasònica del múscul Biceps femoris amb l'objectiu d'esbrinar de forma no destructiva el seu nivell de pastositat. A més, amb la finalitat d'analitzar millor aquest defecte de textura, es van analitzar la composició, la degradació proteica, la textura instrumental i la microestructura dels pernils. Les mostres pastoses van presentar l'índex de proteòlisis més alt (38.7% comparat amb el 33.1% dels pernils no pastosos), van mostrar la degradació estructural més rellevant (estructures miofibrilars fusionades i aparició de grans buits) i, en conseqüència, van ser les més blanes (5.4 N de duresa en comparació amb els 16.7 N dels pernils no pastosos) i van presentar el comportament viscós més intens (0.434 comparat amb el 0.372 dels pernils no pastosos), encara que es va trobar una gran variabilitat experimental. L'avaluació no destructiva duta a terme mitjançant ultrasons va revelar que l'atenuació ultrasònica es podria aplicar amb èxit per a la classificació de les rodanxes de pernil curat segons el seu nivell de pastositat. Així, com més gran va ser la pastositat, major va ser l'atenuació ultrasònica, sent el coeficient d'atenuació mitjà de les mostres amb alta, mitjana i sense pastositat 48.2, 45.4 i 43.1 Np/m, respectivament. No obstant això, la velocitat ultrasònica va ser molt similar en totes les mostres de pernil, independentment del seu nivell de pastositat. Com es va observar en els pernils sencers, la velocitat ultrasònica no va ser un paràmetre satisfactori per a detectar el defecte de pastositat en pernil tallat a rodanxes, ja que la gran influència de la composició en la velocitat ultrasònica sumada al contingut similar de sal i humitat de les mostres, independentment del seu nivell de pastositat, va donar lloc a una velocitat similar en tots els nivells de pastositat. Es van desenvolupar dues tècniques d'ultrasons acoblats per aire, tant en manera transmissió-recepció com en pols-eco, per a caracteritzar la textura de pernil curat. El caràcter no invasiu dels ultrasons acoblats per aire permet dur a terme mesures sense contacte, facilitant la seua aplicació a nivell industrial en comparació amb les tècniques ultrasòniques convencionals, ja que poden realitzar-se mesures a major velocitat, sense alterar la superfície del material i evitant la contaminació creuada entre aliments. Quant a les mesures de correcció de defectes texturals en pernil curat, es van avaluar tractaments tèrmics moderats en dos medis de calfament diferents (aigua i aire). A més, es va considerar la viabilitat d'intensificar aquests tractaments mitjançant l'aplicació d'ultrasons de potència. Per a això, es van calfar rodanxes de pernil curat comercial envasades al buit en medi líquid, amb i sense l'aplicació d'ultrasons, a diferents temperatures (40, 45 i 50 °C), mesurant la temperatura en els músculs Biceps femoris i Semimembranosus. Respecte als tractaments en aire, es van utilitzar cilindres de pernil curat comercial envasat al buit. En el primer set d'experiments, el pernil es va calfar a velocitat d'aire constant (2 m/s) fins que es van aconseguir diferents temperatures (40, 45 i 50 °C). Mentre que, en el segon, el pernil es va calfar a temperatura d'aire constant (50 °C) a diferents velocitats (1, 2, 3, 4 i 6 m/s). En els dos sets, els tractaments es van dur a terme amb i sense l'aplicació d'ultrasons de potència, mesurant la temperatura en el centre del cilindre. Els tractaments tèrmics es van prolongar fins a aconseguir la temperatura objectiu, definida 5 °C per davall de la temperatura del medi de calfament (aigua o aire); així, no es va dur a terme una fase de manteniment de la temperatura i només es va considerar la fase de calfament dels tractaments tèrmics. Les cinètiques de calfament del pernil tractat tant en aigua com en aire es van descriure matemàticament mitjançant un model de conducció de calor. Una vegada finalitzat el calfament, es van avaluar els canvis texturals del pernil (duresa i comportament elàstic). Els experiments van mostrar que l'aplicació d'ultrasons de potència va accelerar la transferència de calor, reduint significativament (p<0.05) el temps de calfament i augmentant la difusivitat tèrmica aparent fins a un 51 i 37% en els tractaments tèrmics en aigua i aire, respectivament. En el cas dels tractaments tèrmics en aigua, l'augment de la temperatura durant el calfament va provocar una intensificació ultrasònica menor (la difusivitat tèrmica aparent va augmentar un 51% a 40 °C comparat amb el 21% a 50 °C). Per contra, en les experiències en aire, com més alta va ser la temperatura, més efectiva va ser l'aplicació dels ultrasons (la difusivitat tèrmica aparent va incrementar un 5% a 40 °C comparat amb el 38% a 50 °C). L'efecte de l'aplicació dels ultrasons va disminuir amb l'augment de la velocitat de l'aire, sent mínim amb la velocitat d'aire més alta assajada (la difusivitat tèrmica aparent va augmentar un 21% a 1 m/s comparat amb el 5% a 6 m/s). Quant als canvis de les propietats texturals del pernil després dels tractaments tèrmics moderats a temps curts, es va observar un augment en la seua duresa i en el seu comportament elàstic. Finalment, es va abordar la correcció de textura en pernil curat amb diferents nivells de pastositat. Per a això, es van calfar rodanxes de pernil amb alta, mitjana i sense pastositat envasades al buit en medi líquid a 40 i 50 °C durant temps més llargs (5 h, incloent les fases de calfament i manteniment) que en les experiències només de calfament, amb i sense l'aplicació d'ultrasons de potència durant la fase de calfament. La textura (duresa, comportament elàstic i adhesivitat) i la microestructura del pernil es van avaluar tant en les mostres tractades com en les control. Després dels tractaments tèrmics moderats, la textura del pernil es va veure millorada perquè la seua duresa va augmentar (102%) i el seu comportament viscós va disminuir (11%). En mitjana, l'augment de la duresa a 50 °C va ser un 159% major que a 40 °C, mentre que la disminució del comportament viscós va ser un 13.5% major a 50 °C que a 40 °C. L'adhesivitat del pernil també es va veure disminuïda, independentment de la temperatura de tractament, observant-se una reducció del 55%. L'aplicació d'ultrasons de potència durant la fase de calfament no va implicar cap canvi textural addicional. Així mateix, després dels tractaments tèrmics, la microestructura dels pernils amb alta pastositat va canviar notablement, experimentant una severa contracció de les miofibrilles, el que va contribuir a explicar els canvis de textura esmentats. En conclusió, la pastositat és un defecte de textura rellevant i molt complex en pernil curat. L'ús d'ultrasons per contacte i la mesura de l'atenuació ultrasònica podria considerar-se una tecnologia potencial per a detectar i caracteritzar de forma no destructiva la pastositat en rodanxes de pernil curat. Futurs treballs haurien d'estar orientats a l'aplicació d'aquesta tecnologia per a la identificació de pernils pastosos sencers, considerant per a això l'ús d'ultrasons acoblats per aire. A més, l'ús de tractaments tèrmics moderats en medi líquid o gasós podria ser un mètode viable per a corregir la textura defectuosa de pernils curats i l'aplicació d'ultrasons de potència durant la fase de calfament podria ser una forma rellevant d'accelerar els tractaments tèrmics. / Gracias a la Universitat Politècnica de València por concederme la beca para realizar mis estudios de doctorado, así como a los proyectos de investigación en los que he participado (RTA2013-00030-C03-02 y RTA2017-00024-C04-03) / Contreras Ruiz, M. (2020). Use of ultrasound for the characterization and correction of textural defects in dry-cured ham [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/153142 / TESIS / Compendio