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Processing parameters involved in the development of texture and tyrosine precipitates in dry-cured ham: Modelisation of texture development
Abstract
The aim of this study was to quantify the effects of different processing parameters on texture development and the incidence of white film and tyrosine crystals in dry-cured ham. Hams were dry-salted for 0.65, 0.8 or 1.0 days/kg. After drying for 45 days at 5 °C, they were dried at 10, 15 or 20 °C until reaching 33% weight loss and, thereafter, dried at 25 °C until reaching 36 or 40% weight loss. The salting time, drying temperature and target weight loss significantly affected the texture and incidence of white film and tyrosine crystals. A beneficial effect of drying at 20 °C on texture was found, which was especially important for low target weight loss (33%). Besides, hams dried at 20 °C and those with 40% weight loss showed higher incidence of tyrosine crystals. Contour plots and predictive models for texture can be used to define optimal processing parameters
... This is inconsistent with the PI measured in the present study, showing a decreasing trend with the storage. Perhaps the apparent inconsistency might be clarified with the recent study of Coll-Brasas, Gou, Arnau, Olmos, and Fulladosa (2021) showing that tyrosine precipitation is a much more complex issue, depending on other factors such as differences in structural damages, salt intake dynamics or fat content (slowing down tyrosine diffusion); demonstrating for instance fairly different tyrosine crystal appearance at similar PI. Likewise, Pé rez-Santescolástica et al. (2018) demonstrated that tyrosine levels did not increase along with increased proteolysis (i.e. ...
... Thus, Gou et al. (2008) reported a change in the TRC (90s of relaxation) from 0.769 in the case of 6 days salting (8% d.m. of X s ) to 0.725 after 14 days (12% d.m. of X s ). Coll-Brasas, Gou, Arnau, Olmos, and Fulladosa (2021), meanwhile, observed a reduction in the TRC (90s) from 0.671 to 0.634 in dry-cured hams salted for 7 (14% d.m. of X s ) and 12 days (17% d.m. of X s ), respectively. ...
In conventional ultrasonic techniques, the necessary contact between the sensor and the product has constrained the implementation of ultrasound for quality control purposes in the meat industry. The use of novel air-coupled ultrasonic technologies provides multiple advantages linked to contactless inspection. Therefore, this study aims to compare the feasibility of contact (C; 1 MHz) and non-contact (NC; 0.3 MHz) ultrasonic techniques for monitoring the physicochemical modifications undergone by beef steaks during dry salting after different times (0, 1, 4, 8 and 24 hours). Experimental results showed that the ultrasonic velocity increased during salting, which was linked to the reduction in Time-of-Flight ratio (RTOF) and sample shrinkage (velocity C: R2 = 0.99; velocity NC: R2 = 0.93 and RTOF C: R2 = 0.98; RTOF NC: R2 = 0.95). In terms of the compositional changes provoked by salting, the velocity variation (△V) increased linearly (C: R2 = 0.97; NC: R2 = 0.95) with the salt content. As for textural parameters, hardness (C: R2 = 0.99; NC: R2 = 0.97) and relaxation capacity (C: R2 = 0.96; NC: R2 = 0.94) were well correlated with the △V through power equations. Experimental results reflected that the performance of the non-contact ultrasonic technique was similar to that of the contact technique as regards the monitoring of the physicochemical changes undergone by beef steaks during dry salting.
... The structural proteins in muscle were hydrolyzed by cathepsins and calpains leads to the destruction of ultrastructure, which was important the formation of dry-cured meat product's texture. The texture parameters of dry-cured meat products include hardness, springiness, factorability, adhesiveness, and cohesiveness, etc. Structural proteolysis (proteins associated with the thick and thin filaments, the Z-disks, and the costamere, etc.) could break down muscle structure, which promotes texture development (Coll-Brasas et al. 2021;Harkouss et al. 2015). Myofibril proteolysis could lead to changes in structure (myofibril degradation, extracellular space, and muscle cross-sectional area, etc.) of muscle cells and texture (hardness, factorability, and springiness) of dry-cured ham (Contreras et al. 2020;Harkouss et al. 2015;. ...
NaCl is the main curing agent in dry-cured meat products, and a large amount of NaCl addition leads to high salt content of final products. Salt content and composition are important factors affecting the activity of endogenous proteases, which in turn could affect proteolysis as well as the quality of dry-cured meat products. With the increasing emphasis on the relationship between diet and health, reducing sodium content without sacrificing quality and safety of products is a great challenge for dry-cured meat industry. In this review, the change of endogenous proteases activity during processing, the potential relationship between sodium reduction strategy, endogenous proteases activity, and quality were summarized and discussed. The results showed that sodium replacement strategy and mediated-curing had a complementary advantage in influencing endogenous proteases activity. In addition, mediated-curing had the potential to salvage the negative effects of sodium substitution by affecting endogenous proteases. Based on the results, a sodium reduction strategy that sodium replacement in conjunction with mediated-curing based on endogenous proteases was proposed for the future perspective.
... This is inconsistent with the PI measured in the present study, showing a decreasing trend with the storage. Perhaps the apparent inconsistency might be clarified with the recent study of Coll-Brasas, Gou, Arnau, Olmos, and Fulladosa (2021) showing that tyrosine precipitation is a much more complex issue, depending on other factors such as differences in structural damages, salt intake dynamics or fat content (slowing down tyrosine diffusion); demonstrating for instance fairly different tyrosine crystal appearance at similar PI. Likewise, Pé rez-Santescolástica et al. (2018) demonstrated that tyrosine levels did not increase along with increased proteolysis (i.e. ...
The environmental impact of livestock production is under scrutiny nowadays and is being situated both on a global level and local level. On a global level, the global warming potential (GWP) of meat production is criticised. On a local level, the excretion of nitrogen (N) and phosphorus (P) is of concern as excess nutrients may lead to water eutrophication and soil acidification. The ERA-NET project SuSI evaluated if immunocastration may act as an ecologically, socially and economic more sustainable alternative compared to pork production with surgical castrates (SCs) and boars (BOs). Here, we report the environmental impact of immunocastrates (ICs) vs SC and BO, based on four trials carried out by European SuSi partners. More specifically, we aimed to compare IC with SC and BO in terms of GWP, N and P excretion per kg of pork production and test if this differed between experiments. There was an interaction between trial and sex category (PTrial × Sex category
... Meat product quality is determined by physicochemical, sensory, and hygienicsanitary properties [5], and many factors can affect these parameters in dry-cured ham, such as raw material [6] or processing technologies [7] such as salting [8] cutting [9], and drying, which has an effect on texture [10]. ...
This study determined the effect of adding three concentrations of saffron (A: high, B: medium, and C: low) on vacuum-packaged dry-cured ham slices. The pH and the color coordinates were assessed at 0, 7, 14, 28 and 60 days of storage, and sensorial quality (visual appearance, odor and flavor) and safranal content were analyzed at 7, 14, 28 and 60 days. Saffron concentration did not significantly affect the pH or color (except in a* (redness) and b* (yellowness) at day 28; p < 0.001). Storage period affected pH values (p < 0.001) in all groups with a significant decline from day 28 (p < 0.05); the color coordinates showed a high stability (only L* (lightness) varied in the C group samples; p < 0.01). Sensorial quality did not vary with the time in any group. Significant differences were found among groups in visual appearance (p < 0.05) and flavor (p < 0.001) at day 14 and in odor at day 14, 28, and 60. In general, the C group samples obtained the highest scores. Safranal content varied significantly with the time in a different way in each group, with differences among groups at day 14 and 60 (p < 0.001).
New consumer demands have increased the need for improved food processing and new value-added products that meet the latest quality standards. Changes in eating habits may lead to a preference for lower sodium products, making accurate labelling and nutritional claims important for the industry. The aim of this work was to study the application of Multi-energy X-ray absorptiometry (MEXA) for the determination of nutritional information in sliced packaged dry-cured ham for the industry. The effect of the acquisition conditions, the analysis approach, fat content and measured area of slices, as well as the potential of this technology for the inclusion of a verified ‘salt reduced’ nutritional claim, were analyzed in two industrial case studies. Two hundred and ten packets of sliced dry-cured ham were scanned using MEXA equipment. Two regions of interest were selected to study the effect of thickness on the model's precision. Salt content could be predicted with a RMSEP of 0.346% and 0.403% when acquisition conditions were 80 keV and 110 keV respectively. When used by the industry, the classification performance for a ‘salt reduced’ labelling claim depends on the mean salt content and heterogeneity of the company's production and on the threshold value selected for class definition. However, to support consumers personalized nutrition through precise labelling, implementation of MEXA technology together with labelling system is necessary.
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.
Pastiness is a dry-cured ham defect that can be determined by sensory and chemical analysis. Since pastiness produces an increase of saliva viscosity, rheology might be useful to instrumentally evaluate this defect. The aim of this study was to evaluate the rheological behaviour of water extracts obtained in vitro mimicking the mastication of dry-cured ham samples with different pastiness intensities. Commercial samples from different groups (non-pastiness (NPG), medium pastiness (MPG) and high pastiness (HPG) groups) were sensorially and rheologically analysed. Effect of temperatures and HPP treatments at 7 ºC, 20 ºC and 35ºC were also evaluated. Results showed that apparent viscosity of the water extracts increased with the increase of pastiness and decreased with temperature. Significant differences (p<0.05) were observed between NPG/MPG and HPG samples and between 25 ºC and 37 ºC in HPG. After HPP, sensory pastiness disappeared in samples from MPG at any temperature and decreased from 6.8 to 0.2 in samples from HPG only when HPP35 was used. Although the increase on viscosity of oral fluid is related to the sensory pastiness, other factors seem to be involved in the mechanism of pastiness perception. Despite this, HPG samples can be distinguished from MPG and NPG samples.
BACKGROUND
Reduction of the salt (NaCl) content in typical Italian dry‐cured ham is intended to reduce sodium dietary intake to meet World Health Organization (WHO) recommendations for the prevention of serious diseases. This reduction is a complex issue because of the multiple roles that salt plays in the product. Hams that were processed to obtain a final product with target salt levels (hams with reduced salt concentration and controls) were analyzed using chemical parameters (salt, moisture, fat, and proteolysis indexes). Their sensory properties were described by a trained panel and 87 consumers evaluated the impact of salt reduction on their liking for the products.
RESULTS
The dry‐cured hams under investigation are representative of Italian dry‐cured hams, which are considered to be low and medium to high in terms of salt content. Consistent with the role of salt in proteolytic enzymes inhibition, there was an increase in the proteolysis index in fully matured dry‐cured hams with reduced salt content. Salt level affected saltiness perception but also texture, color, and, to a lesser extent, flavor intensity in matured dry‐cured hams. On average, reduced‐salt dry‐cured hams resulted in increased consumer liking. However, the resulting three consumer segments (37%, 27%, and 36% of the consumer cohort, respectively), differed in the acceptability ranking given to reduced‐salt hams and controls.
CONCLUSION
The tested reduction in salt content, besides improving the nutritional profile of dry‐cured ham, was effective in increasing consumers’ acceptance. These results were useful for exploring the effect of reducing salt concentration on consumer liking for dry‐cured hams. © 2020 Society of Chemical Industry
The use of low-protein (LP) feeds is a good strategy to reduce the environmental release of N compounds, but their influence on the quality of the products must be considered. This study explored the influence of LP diet and two pig breeds (BR) with different lean growth ability on the quality traits of dry-cured hams. We analysed 40 left dry-cured hams from pigs of two BR [Duroc-Danbred crosses (Danbred) and Duroc × Large White crosses (Anas)] fed either conventional (147 to 132 g/kg, crude protein) or LP diet. The LP had a crude protein content reduced by 20% with respect to the conventional. The differences in ham quality resulting from protein reduction were small, with a decrease of the protein and an increase of the lipid content of the ham slice in Anas, but not in Danbred (BR × Diet interaction; P = 0.043). Therefore, the use of LP would be feasible and sustainable, without detrimental effects on products. It was found the pig genotypes with different potentials for lean growth may affect the initial ham weight, fat cover and seasoning losses of hams, but they appear to affect little other chemical, physical and textural quality traits of the dry-cured hams.
The effect of pH before salting on pork quality was studied in two sets of experiments: 904 hams, set A; and 104 hams, set B; the latter was used to verify the results from A. After pH measurements, the hams were subjected to the traditional process for producing Spanish dry-cured ham and then evaluated by an expert panel to correlate the sensory characteristics to the pH measurement before salting. The parameters evaluated were pastiness, softness, anomalous cut colour, crusting and white spots. Moisture, non-protein nitrogen, salt, protein, nitrate and nitrite were determined in samples from both experiments. The results obtained in experiment A showed that pastiness is closely related to the pH before salting (p<0.001), but not softness. From the receiver operating characteristics curve, a cut-off point of pH of 5.55 was selected to classify the raw material in two groups: normal-pH and low-pH hams. The pH before salting can also be correlated with the appearance of anomalous cut colour and crusting in hams. White spots were absent in both pH groups. Regarding compositional parameters, there were significant differences in moisture (p<0.001), salt (p<0.001), protein (p<0.001), non-protein nitrogen (p<0.001) and nitrate (p<0.05) contents between low-pH and normal-pH hams. The results from experiment B, confirmed the relationship between pH before salting and the appearance of defective texture and colour in the final product. Also results from experiment B confirmed the compositional parameters found in experiment A. Thus, the pH before salting is a good predictor for meat quality allowing the classification of the raw material in the first stage of manufacture. After classification, some modifications to the processing can improve the final characteristics of dry-cured hams.
This study reviews the factors of pig production that impact the quality of dry-cured ham. When processing is standardized, the quality of the final dry-cured product is primarily determined by the quality of the meat before curing (green ham). This has been defined as the aptitude for seasoning and is determined by the green ham weight, adipose tissue quantity and quality, meat physico-chemical properties and the absence of visual defects. Various ante-mortem factors including pig age and weight, genetic type, diet, feeding strategy and slaughter conditions determine green ham properties such as the dynamics of water loss, salt intake and, as a consequence, proteolysis and lipolysis. Muscle conditions (pH, salt concentration, water content and availability, temperature) influence enzymatic activity and development of characteristic texture and flavor. Generally, hams of older and heavier pigs present better seasoning aptitude because of higher adiposity. Adiposity is also positively correlated with fat saturation, which is desired to avoid rancidity and oiliness. The fatty acid profile of tissue lipids can be manipulated by diet composition. Feeding strategy affects tissue accretion and protein turnover, thus directly impacting proteolysis. With respect to the impact of pig genotype on dry-cured ham quality, local breeds are generally considered more suitable for producing quality dry hams; however, the majority of dry-cured hams on the market today are from modern pig breeds raised in conventional systems, providing lean hams. The importance of all these factors of pig production is discussed and synthesized, with an emphasis on the main difficulties encountered in dry-cured ham production.
Globular and fibrous proteins are compared with regard to structural behaviour on heating, where the former expands and the latter contracts. The meat protein composition and structure is briefly described. The behaviour of the different meat proteins on heating is discussed. Most of the sarcoplasmic proteins aggregate between 40 and 60 °C, but for some of them the coagulation can extend up to 90°C. For myofibrillar proteins in solution unfolding starts at 30-32°C, followed by protein-protein association at 36-40°C and subsequent gelation at 45-50°C (conc.>0.5% by weight). At temperatures between 53 and 63°C the collagen denaturation occurs, followed by collagen fibre shrinkage. If the collagen fibres are not stabilised by heat-resistant intermolecular bonds, it dissolves and forms gelatine on further heating. The structural changes on cooking in whole meat and comminuted meat products, and the alterations in water-holding and texture of the meat product that it leads to, are then discussed.
The aim of the present study was to describe the effect of NaCl and pH on the relationship between water content and hardness, cohesiveness and springiness in dry-cured muscles. The experiment was undertaken using 18 hams, selected in a commercial slaughterhouse. Half of the hams had a pH<5.7 and the rest a pH>6.2, measured on the semimembranosus muscle at 24-h postmortem. The semimembranosus and biceps femoris muscles were cut from hams, cured and individually packaged in bags and were laid in trays in a room at 2±2°C for 45days. Thereafter nine samples from each muscle were shaped like a parallelepiped and dried until different levels of drying, ranging from 28.5% to 59.7% water content, were attained. The rest of the muscle was ground and packaged until its subsequent physicochemical analysis. At the end of the drying period, a Texture Profile Analysis was used to determine textural parameters. The results indicated that for a range of X (kg H(2)O/kg dry matter) between 0.8 and 1.3 the hardness remains practically unchanged while for X<0.6 the hardness increases substantially. The samples from hams with low pH(SM) had greater hardness, cohesiveness and springiness than those from hams with high pH(SM). Dry-cured muscles with lower NaCl content showed lower hardness, cohesiveness and springiness, especially in those with pH(SM)>6.2. At X values lower than 0.6 the hardness was more influenced by water content than by NaCl content or pH(SM).
This study compares the profiles of water activity (a(w)), water content (X) and texture in loin with crusted surface versus those profiles in loin without crust, and establishes a mathematical model able to describe hardness based on a(w) and/or X. Two loins (m. longissimus dorsi) were dry-cured, aged and then each one was divided into four pieces. Two of them were dried at 15±2 °C, 50±3% RH (CL treatment) and the other two were dried at 2±2 °C, 80±3% RH (NCL treatment). The pieces of CL were dried under more severe conditions in order to develop a crust on the surface. Three-millimetre thick slices were taken from the most external part towards the inner part. The slices were prepared (10×10×3 mm) for texture profile analysis (TPA). Measurements of a(w) and X were carried out on each slice. Variance analyses and non-linear regression analyses were performed to create a model for loin hardness prediction through X and/or a(w) and a linear regression model for cohesiveness and springiness. CL loins showed a higher hardness and chewiness and lower cohesiveness at the surface (3-mm thickness) than the NCL loins. Hardness and chewiness, fitted with a non-linear model, were better described by X than by a(w). Springiness showed a low relationship with X and a(w). The on-line monitoring of X and a(w) at the surface of the product would enable an estimation of the profiles of water content, a(w) and texture and it could be, therefore, a useful tool to avoid crusting.
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.
There is a new trend to produce dry-cured ham from lamb in shorter times by deboning the ham before salting to later obtain restructured hams that are easier to dry and slice. However, little information about the physicochemical characteristics of Norwegian Fenalårs during the process or the safety implications of their elaboration procedures is reported in the literature. The aim of this study was to characterize the colour, texture and physicochemical properties of restructured Fenalårs when using Standard Salting (SS), Salt Reduced (SR) and a Non-Nitrite Salt Reduced (NNSR) treatments. Microbiological safety implications of the elaboration process when using the different salting treatments were also assessed using predictive microbiology. To do so, sixty Fenalårs were elaborated using a Standard Salting (SS), a Salt reduced (SR) and a Non-Nitrite Salt Reduced (NNSR) treatments. Physicochemical characterization (instrumental colour and texture and Zinc Protoporphyrin content) was performed at the end of the process using thirty Fenalårs. The rest of the Fenalårs were used to characterize the product through the elaboration process (pH and aw) for the evaluation of microbiological hazards when using the different salting treatments using predictive microbiology. Results showed a significant increase in softness when reducing salt content and a decrease of redness when no nitrite was used, attributed to the formation of ZnPP content instead of nitrosylmyoglobin. In terms of risk assessment, the decrease of aw through the elaboration process reduced the growth capacity of all the microorganisms evaluated. However, microbiological safety implications in salt reduced Fenalårs are important, especially when no nitrite was added, because the considerable increase of growth potential of L. monocytogenes. The increase of growth potential of proteolytic C. botulinum is very little and no relevant effect of nitrite on growth potential of S. aureus was observed.
Predictive microbiology and optimization of the process to enhance ZnPP formation can help to ensure safety and quality of salt reduced restructured Fenalårs without additives.
Effect of reduced salting and pig sex on the quality of Slovenian dry-cured ham Kraški pršut was studied. A total of 48 hams from 24 crossbred pigs (12 gilts, 12 castrates) were submitted to two different salting regimes; standard salting for 18 days (HS hams, n = 24) and shortened salting (LS hams, n = 24) for 10 days. Reduced salting time effectively reduced salt content but resulted also in higher extent of proteolysis of LS hams which was associated with differences in texture and colour of biceps femoris muscle. Lower fat oxidative stability was observed in HS hams. With regard to sex effect, the hams originating from gilts were more proteolysed which was associated with differences in texture and colour. Lipid oxidation was similar in gilts and castrates.
The dry-cured pork ham industry lacks non-destructive quality control techniques able to characterize relevant textural defects, such as pastiness or softness. The aim of this study is to analyze the feasibility of using different destructive and non-destructive techniques to characterize pastiness in dry-cured ham. Dry-cured ham processing was modified in order to induce different pastiness intensities over a wide range of moisture and salt contents. Afterwards, pastiness was assessed by sensory analysis and samples classified as non-pasty, medium-pasty and highly-pasty. Finally, chemical, textural, microstructural (LM and TEM) and ultrasonic analyses (velocity and attenuation coefficient) were carried out.
Samples with a high degree of pastiness experienced an increase of 16.8% and 16.7% as regards the proteolysis index and relaxation capacity, respectively, and a 67.7% decrease in hardness compared to non-pasty hams. The microstructural analysis revealed that pastiness brought about great structural degradation. Ultrasonic velocity was significantly related to the salt (r = 0.79) and moisture contents (r = 0.69), but no influence of pastiness was found on the velocity. However, the attenuation coefficient increased as the pastiness rose and could be considered as a useful parameter for characterizing this complex textural defect. Therefore, ultrasound could be used not only to carry out a non-destructive characterization of dry-cured ham composition but also to assess pastiness.
High pressure processing is mainly used to eliminate pathogenic microorganisms and extend the shelf-life of dry-cured hams, but it also modifies its texture. These changes might be different depending on the initial textural characteristics. In this study, texture, colour and colour stability were evaluated after pressurization at 600 MPa during 6 min at 7 °C, 20 °C and 35 °C in samples with different textural characteristics (no pastiness, medium and high pastiness groups). HP treatments produced an increase of hardness (F 0 ) and lightness (L*) values and a decrease of softness/pastiness (Y 2 and Y 90 ) and redness (a*) values at any processing temperatures. However, the increase of F 0 and L* values was more pronounced in non–pasty samples. In samples with high pastiness and softness, HP processing at high temperature (35 °C) reduced the intensity of pastiness. However, texture of hams with non-pasty texture might be negatively affected. Therefore, the optimal temperature of HP processing depends on the textural characteristics of dry-cured hams
The impact of low temperature treatment and its combination with ultrasound has been evaluated in order to correct texture defects in dry-cured hams. A total of 26 dry-cured hams, classified as high proteolysis index (PI>36%), were used. From these hams, ten slices from each ham sample were cut, vacuum packed and submitted to three different treatments: control (without treatment), conventional thermal treatments (CV) and thermal treatment assisted by power ultrasound (US). The impact of these treatments on instrumental adhesiveness, free amino acid and volatile compounds profile were assessed. Statistical analysis showed that both US and CV treatments, significantly (P < .001) decreased the instrumental adhesiveness of dry-cured hams from 85.27 g for CO to 40.59 and 38.68 g for US and CV groups, respectively.
The total free amino acid content was significantly (P < .001) affected by both treatments, presenting higher values the samples from the US group (6691.5 vs. 6067.5 vs. 5278.2 mg/100 g dry matter for US, CV and CO groups, respectively). No significant differences were observed between US and CV treatments. All the individual free amino acids were influenced by ultrasound and temperature treatments, showing the highest content in sliced dry-cured ham submitted to ultrasounds at 50 °C, except for isoleucine which presented the highest level in samples from CV group. Similarly, significant differences (P < .05) were also detected in the total volatile compound content between CO and US groups, with a higher concentration in the CO batch (56,662.84 AU × 10³/g of dry-cured ham) than in the US treatment (45,848.47 AU × 10³/g of dry-cured ham), being the values in the CV treatment intermediate (48,497.25 AU × 10³/g of dry-cured ham). Aldehydes, ethers and esters, carboxylic acids and sulphur compounds were more abundant in the CO group, while CV group showed higher concentrations of ketones, alcohols and nitrogen compounds.
The fast and non-destructive inspection of salt uptake after the salting phase of dry-cured ham process still remains a goal to allow the optimization of the salting process.
This work aims to show the capability of a single frequency, magnetic induction (MI) system, to predict salt (NaCl) content of whole hams after the salting stage. MI system is based on the measurement of the perturbation caused by an alternating excitation magnetic field on a conductive sample; the perturbation is typically detected by measuring the current induced in a suitable receiver coil. One hundred and fifty-nine hams were scanned by the MI scanner before and after the salting phase. Hams were dissected, separated into muscle and fat parts, and analysed for salt content (potentiometric method). Predictive models (multi-linear regression analysis) of the salt gain in hams were developed, based on output signals generated by the MI system. The model including independent variables given by scanning ham when raw and after the salting, achieved the best accuracy (R² = 0.89; RMSEC = 0.19%). It was concluded that variations in electrical conductivity originated by different salt content and revealed by magnetic induction have potential application to predict the salt content inside entire bone-in hams after salting process.
Marbling in sliced dry-cured ham affects consumer acceptability and the sensory quality of the product. This study presents an automated marbling grading system of dry-cured ham slices which allows for the characterization and classification of the product. Firstly, a sensory marbling grading scale was developed by a panel of experts who did not only take into account the amount of visual fat content, but also the distribution of the fat flecks. This scale was used for the design of an automatic classification system of dry-cured ham based on segmenting intramuscular fat. 643 regions of interest (ROI) of the slice were categorized by a panel of experts using the marbling grading scale and later segmented by the computer system. From the segmented ROI, 48 features (geometrical and textural) were extracted. Using all the data several classifiers were built using two machine learning techniques namely Support Vector Machines (SVM) and Neural Networks (NN). Different feature selection algorithms were tested to select the optimal subset of features. Results show that with a reduced number of features, 89% of the samples could be correctly classified. Performance was better for SVM algorithms than for NN.
This work addresses the use of ultrasound (US) and medical dual energy X-ray absorptiometry methods to predict the fat content in green pork hams. Ultrasonic velocity (υ) and X-ray absorption were measured in 78 green hams. An increase in the fat content involved an increase in υ and a decrease in the X-ray attenuation measured at 2°C. Models developed to predict the fat content from the ultrasonic velocity or X-ray parameters provided errors of 2.97% and 4.65%, respectively. The combination of both US and X-ray technologies did not improve prediction accuracy. These models allowed green hams to be classified into three levels of fatness, with 88.5% and 65.4% of the hams correctly classified when using models based on ultrasonic and X-ray parameters, respectively. Therefore, US and X-rays emerge as useful quality control technologies with which to estimate the fat content in green pork hams.
Copyright © 2015 Elsevier Ltd. All rights reserved.
Salt uptake variability in dry-cured ham batches is a problem for the dry-cured ham industry because part of the hams have either an excess or a lack of salt and therefore are more prone to sensory defects. The aim of this study was to evaluate the feasibility of an X-ray inspector for a non-destructive, on line determination of the salt uptake in entire bone-in hams during the salting procedure. Moreover, its usefulness in combination with a modified salting procedure to reduce the salt content and within batch variability was evaluated in an industrial case study. Predictive models for salt content, accurate enough for classification purposes (RMSEV = 0.210−0.257%), were developed using only one X-ray energy (50 kV). The use of an X-ray inspector in combination with slight modifications of the process allowed the reduction of the average salt content a 13.75% and 26.67% and a within-batch standard deviation from 0.45% to 0.21% or 0.26% depending on the reduced target salt content.
The effects of a curing salt composition (with and without nitrifying salts), and the pH at 24h postmortem (pH24>6.0, 5.5<pH24<6.0 and pH24<5.5) were evaluated in the Semimembranosus (SM) and Biceps femoris (BF) muscles of pork legs for compositional and nutritional attributes at the end of dry-cured ham ageing. The muscles free amino acid profile (FAA) was not influenced by nitrifying salts. The pH24 was the factor which had the greatest consequences on the dry-cured ham characteristics analysed. The increase in nicotinamide and decrease in pyridoxine by curing salts and the decrease in both vitamins by pH24, had no major effect on the nutritional value of the dry-cured ham because the remaining amounts were within the intervals found in the nutritional data base for dry-cured ham. The results obtained suggested a cooperative action of vitamins B3 and B6 and the antioxidant enzyme system against oxidation. Thiobarbituric acid reactive substances (TBARS) were reduced by the addition of curing salts but were low in all cases, suggesting high antioxidant stability in dry-cured ham which was corroborated by the low volatile aldehyde contents.
The compositions of the white film and white crystals in dry-cured hams were evaluated. White film and white crystals were extracted by 4 M HCl and the amino acid composition was determined by capillary gas chromatography and HPLC. Tyrosine was the main component of the white film and white crystals followed by phenylalanine. The relative amounts of tyrosine and phenylalanine were higher in white film, whereas the other amino acids analysed did not change in the cut surface due to the presence of white film. The amounts of amino acids on the surface of hams with high and moderate levels of white film did not differ.
The changes of moisture, pH, NaCl, nitrate and nitrite in different zones of the ham during the process were evaluated in 15 normal and 15 PSE hams. No difference in pH was found between PSE and normal hams. When all the sampling times were analysed together, the PSE hams were found to contain more moisture and NaCl than normal hams in certain muscles. In most zones, pH increased during the process. The external zones showed a higher salt concentration at the beginning, but this trend reversed during aging owing to salt penetration from the drier external zones to the more humid inner zones. The total NaCl in the lean tissue of the hams increased after salting and remained constant after the resting phase. Nitrate diminished quickly during the resting period, especially in the external zones, whereas nitrite increased after the salting period and did not exceed 10 ppm at the end of the process.Dry cured ham is a nonhomogeneous product that undergoes a salting and dehydration process that determines the dynamics of the migration of the water, NaCl, nitrate and nitrite.
In Spanish dry-cured ham the temperature is sometimes increased at a specific stage in order to accelerate the ageing process. In this study the effect of temperature during the final month of a 6-month process on certain physicochemical and sensorial characteristics of hams cured for different salting times was evaluated. Three salting times and three different temperatures (20, 25 and 30°C) during the last month of the process were used. Whole ham weight losses and the incidence of white film and tyrosine crystals on the cut surface were evaluated; and chemical and sensory analysis were carried out on Biceps femoris muscle. Despite reducing white film and tyrosine crystals, an increase of 2 days in salting time, had a slight effect on texture and produced an increase in the salty taste which could be regarded as excessive. Tyrosine concentration, the incidence of white film, brightness, pastiness and piquantness, all of which may negatively affect consumer acceptability, were greater in the hams with 30°C ageing temperature. © 1997 SCI.
White surface film that forms on cut surfaces of country-style ham was identified as crystalline L-tyrosine. Free L-tyrosine averaged 287.3 μmoles/g (5.2% by weight) in the film and 6.1 μmoles/g in ham tissue from which film had been removed. It is concluded that the film forms because the concentration of free L-tyrosine and certain other free amino acids in ham is greater than solubility levels; therefore, crystals form on the cut surface. The absence of surface film on knuckle muscles and film formation on other muscles of the same slice was attributed to higher NaCl (P < 0.05) of the former which decreased catheptic activity.
The effects of freezing, meat pH and storage temperature on the formation of white film and tyrosine crystals in dry-cured hams were evaluated in three experiments. Freezing of green hams did not affect the tyrosine concentration but increased the formation of tyrosine crystals and decreased white film intensity. The incidence of hams with tyrosine crystals and white film was lower in those with high pH meat. White film increased as the storage temperature decreased and was not found to be present around the tyrosine crystals.
The influence of genetics and slaughter time on the sensory characteristics of dry-cured hams was studied. To this end, 341 dry-cured hams, selected from 1257 pigs from five different crosses, including Duroc, Landrace and Large White, in five slaughters distributed over a year (namely, December 2000, March, April, July and November 2001) were sensorially evaluated according to the ISO 8586-2:1994. The sensory parameters assessed were pastiness, softness, colour, ring colour, crusting and marbling. Analysis of the results revealed that both the genetics and slaughter time had a significant effect on the dry-cured ham quality. Thus, warmest months provide dry-cured hams of the highest quality, but with a higher incidence of crusting. Dry-cured hams with the best sensory evaluation for texture and colour were from crossbreed A [(LR × LW) × DU]; while crossbreed D [(LR × LW × DU) × DU] provided the highest percentage of faulty dry-cured hams, except for incidence of crusting. Other parameters, such as the ham weight, relationship between salting days and ham weight, pH before salting and total weight loss, also influenced the properties of the end-product.
The objectives were to evaluate the attitude of butcher and consumer towards soft and pasty texture problems in dry-cured ham and to assess the butcher and consumer behaviour when selecting and purchasing this product. Ninety-nine butchers and 200 consumers were interviewed with 17-question and 20-question surveys, respectively. The texture problems (softness and pastiness) were highly important for both butchers and consumers. The characteristics most frequently considered "important" or "very important" by butchers were processing time, smell/aroma and texture as selection criteria and salty taste and aged/matured flavour as sensory indicators of dry-cured ham quality. According to butchers' opinion, salty taste and their own advice are the factors most frequently considered "important" or "very important" as affecting the consumer's decision to purchase. For the consumer, the sensory attributes were considered more important than extrinsic characteristics when purchasing dry-cured ham.
In the first experiment, the effect of the stress relaxation time on texture evaluation of biceps femoris (BF) muscle from dry-cured hams was studied. The specimens were compressed to 25% of their original height and the crosshead speed was 5mm/s. The force decay versus time was recorded and Peleg's model was fitted with different relaxation times. Whatever relaxation time was used, Peleg's model did not describe simultaneously the initial fall of force and the asymptotic tendency of force decay correctly. The initial force and force decay at 2s and at 90s are proposed to assess texture in dry-cured ham. In the second experiment, stress relaxation (SR) and texture profile analysis (TPA) tests were performed on BF and semimembranosus (SM) muscles of 10 hams with abnormal softness and 10 hams with normal texture, at different assay conditions: sample temperature (4°C or 20°C); compression crosshead speed (1mm/s or 10mm/s). The instrumental texture test and the assay conditions that detected defective textures better depended on the muscle considered: for BF muscle the SR test at 4°C and at 1mm/s and for SM muscle the TPA test at 10mm/s at both 4°C or 20°C.
Thirty-eight Italian dry-cured hams were analysed for cathepsin B activity, proximate composition and proteolysis index and results were related to lean tissue texture, as assessed by an expert panel, in order to search for relationships between excessive softness, a major problem in the raw ham industry, and chemical parameters. Softness was found to be related to protein breakdown which, in turn, was linked with higher residual cathepsin B activity and, to a lesser extent, to lower salt content. Results suggest that the use of raw ham of controlled enzyme activity would improve the texture quality of the end product.
The aim of this study was to investigate the effect of a 10-day ageing at 30±2°C on the texture of dry-cured hams processed at temperatures up to 18±2°C for 12 months in relation with raw ham pH and salting time. Three pH groups (semimembranosus muscle at 24h post-mortem: Low pH<5.7, Medium pH=5.7⩽pH⩽5.9, and High pH>5.9), three salting times (6d, 10d and 14d) and two ageing temperatures (18°C and 30°C) were investigated. Physicochemical characteristics, instrumental and sensory texture and product sliceability were evaluated on biceps femoris and semimembranosus muscles. Hams with pH(SM24)<5.7 should be avoided in order to reduce the incidence of texture problems in dry-cured ham elaboration. Texture problems are especially important in hams with a reduced salt content that are mechanically sliced (not frozen). A 10-day ageing at 30°C could be useful for reducing the soft texture problems in dry-cured hams processed at temperatures up to 18°C for 12 months without affecting the product flavour.
The evolution of biochemical, instrumental colour and texture, sensory parameters and consumer acceptability of 12-month dry-cured hams maintained up to 26 months under "bodega" conditions (18°C, 75% relative humidity) was assessed, in order to investigate the influence of extended ripening on their sensory characteristics and acceptability. Results demonstrated that ham acceptability showed no significant differences (p>0.05) from 12 to 22 months, while it decreased significantly (p<0.05) until 26 months. Principal component analysis of all data brought about a comprehensive explanation of the biochemical, instrumental and sensory parameters involved in the acceptability decrease. In fact, high pastiness and adhesiveness values, as measured by both sensory and instrumental methods, appeared to be most related to decreasing acceptability. Those attributes were the result of an excessive proteolysis, as revealed by biochemical maturation indices.
Pigs of similar genetic backgrounds and feeding regimes were slaughtered in two abattoirs, one carrying out dehairing by scalding and the other by singeing. One ham from each of 80 carcasses was retained. Sixteen fresh hams (8 from each dehairing technique) were used for analysis while 64 hams were processed into dry-cured ham. Sixteen hams (8 from each dehairing technique) were taken for analysis at end of salting (day 14), end of rest (day 78), mid-processing (day 127) and end of processing (day 251). During processing, the water content of all muscles decreased while the salt content increased. The salt concentration in muscle water tended to equalize in all muscles. The nitrogen content of desalted dry matter (i.e. dry muscle tissue) decreased in both Biceps femoris and Semimembranosus. The content of every free amino acid increased with time, except for taurine and glutamine. Electrophoresis of the low ionic strength-soluble fractions showed all protein bands decreased during processing. Electrophoresis of the myofibrillar fractions indicated changes in all bands except actin (42kDa). These changes were more marked in the Semimembranosus than the Biceps femoris in the earlier processing steps. Ultrastructural changes were more marked in Semimembranosus than Biceps femoris. Hardness and chewiness increased in both muscles during the first half of processing then returned to values close to the initial ones in Semimembranosus but changed little in Biceps femoris. The scalded hams lost more weight than the singed ones during processing. The salt content was higher in scalded hams. Water-soluble nitrogen and NPN were higher in singed hams at the end of processing. The scalded hams were saltier and pungent. They had more pronounced aromas of dry ham, rancidity and hazelnut, and less aroma of fresh meat. Their texture was drier and less mellow.
The texture of dry-cured ham is one of the most important factors in consumer quality perception of the product. In this study the texture and mechanical properties of normal and Dark, Firm and Dry (DFD) dry-cured hams were studied as well as the relationship between them. DFD hams were softer, pastier, more crumbly and more adhesive than normal ones despite having lower non-protein nitrogen (p<0.05). One of the reasons for the texture characteristics of DFD hams could be the higher level of moisture observed in the Biceps femoris muscle and the high pH value. The mechanical parameters studied also showed clear differences between the two groups of hams, specially in the inner part which was less affected by the drying process. In general the correlation coefficients between sensorial and mechanical parameters were not very high (0.23-0.62). The use of a non-destructive mechanical test, compressing the ham with a spherical probe, makes it possible for DFD hams to be detected in the earlier stages of the manufacturing process and means that technological changes can be made in order to reduce the problematic texture obtained from this kind of meat.
The aim of the study was to quantify the effect of meat quality characteristics and some processing conditions on the softness of dry-cured biceps femoris (BF) muscles. The BF muscles were dissected from forty hams and classified according to their pH(BF) into three groups: LpH (pH<5.66), MpH (5.66⩽pH⩽6.00) and HpH (pH>6.00). BF muscles within each pH(BF) group were distributed into three different Salting levels (1%, 2% or 4% of added NaCl). Muscles were salted, vacuum-packed and stored at 3°C for 30 days. The post-salting BF muscles were classified into two intramuscular fat (IMF) levels: Low (IMF<4%) and High (IMF⩾4%). Thereafter, the muscles were divided into two pieces and dried at two of the three different Drying levels (1.5, 2 and 2.5g H(2)O/g desalted dry matter). Then, each piece was divided into two samples that were packed in N(2) and stored at 5°C or 30°C for 1 month. Stress Relaxation was used to evaluate texture. Dry-cured BF muscles with initial pH>6.0, with IMF>4% or with added NaCl levels less than 2% were more prone to show soft texture. Softness in dry-cured muscles can be reduced by applying an ageing temperature of 30°C for 30 days, despite increasing proteolysis. The softness reduction by ageing at 30°C compared with 5°C is expected to be higher when applied to drier samples, which show a smaller increase in proteolysis.
The effect of the dry-curing processing time on the release of oligopeptides and amino acids was evaluated with 158 Parma hams subdivided into three groups: (1) traditional processing (450 days); (2) extended processing (570 days); and (3) extended aging (690 days). Most of the oligopeptides and free amino acids detected increased up to the last deadline (690 days); a sharp increase of peptides below 400 Da was the main change in most aged hams. In particular, gamma-glutamyl dipeptides showed a remarkable increase during ham extended aging, acting like permanent taste-active compounds, being unsuitable for further enzymatic breakdown. The pH of fresh hams showed negative relationships (P < 0.001) with most peptides. With regard to free amino acids, the pattern was modified by different processing lengths, together with their taste categories, so that the amino acids having monosodium glutamate-like and bitter tastes were enhanced in more aged hams.
American Society for Testing and Materials. Guidelines for the selection and training of sensory panel members
- Astm
Official method 950.46, moisture in meat, B. air drying
- AOAC
Ipotesi sulla formazione di cristalli di tirosina nei prosciutti crudi da parte dei lieviti
- Comi
Características de jamones con cristales de tirosina
- Silla
Meat pH influence on texture of dry-cured ham with reduced salt content and submitted to different storage temperatures
- Morales
Prosciutto di Parma Denominazione di Origine Protetta-disciplinare generale e dossier di cui all’articolo 4 del regolamento (CEE) no
- Consorzio del Prosciutto di Parma