Subscribe Now Subscribe Today
Research Article
 

Changes on Physico-chemical, Textural, Proteolysis, Lipolysis and Volatile Compounds During the Manufacture of Dry-cured “Lacón” from Celta Pig Breed



Jose M. Lorenzo and Laura Purrinos
 
ABSTRACT

The changes in physico-chemical, textural, proteolysis, lipolysis and volatile compounds during the manufacture of dry-cured Celta “lacón” were studied. The pH value increased during the final stages of processing. While gradually declined over the curing period, TBAR’S values and hardness increased with processing time. The colour parameters, L* (from 38.68 to 35.13), a* (from 19.10 to 14.55) and b* (from 10.05 to 7.67) decreased as processing time increased. In the Free Fatty Acid (FFA) fraction, Saturated Fatty Acid (SFA) showed the highest values at the end of process, while Monounsaturated (MUFA) and Polyunsaturated Fatty Acids (PUFA) presented similar amount. Regarding, Free Amino Acids (FAA), a significant increase (p<0.001) from raw pieces (688.6 mg/100 g of dry matter) to the end of dry-ripening (3309.9 mg/100 g of dry matter) was observed. At the end of process the most abundant FAA detected were arginine, followed by taurine, glutamic acid and alanine, which were up to 270 mg/100 g of TS. Finally, sixty four volatile compounds were identified during the manufacture of dry-cured Celta “lacón”. At the end of process, esters had become the dominant chemical compounds followed by aliphatic hydrocarbons and branched hydrocarbons.

Services
Related Articles in ASCI
Similar Articles in this Journal
Search in Google Scholar
View Citation
Report Citation

 
  How to cite this article:

Jose M. Lorenzo and Laura Purrinos, 2013. Changes on Physico-chemical, Textural, Proteolysis, Lipolysis and Volatile Compounds During the Manufacture of Dry-cured “Lacón” from Celta Pig Breed. Journal of Biological Sciences, 13: 168-182.

DOI: 10.3923/jbs.2013.168.182

URL: https://scialert.net/abstract/?doi=jbs.2013.168.182
 
Received: March 04, 2013; Accepted: March 25, 2013; Published: July 10, 2013

INTRODUCTION

The Celta pig breed raised in Galicia (NW Spain) until the middle of the 20th century, at which time it was substituted for commercial crossbreeds due to their higher productive capacity, prompted an important recession in this autochthonous pig breed. With the help of Regional Government of Galicia and National Government of Spain programs, the Celta pig breed has undergo a recovery in the last few years, dropping from 2.714 animals at the end of 2008 to 4.476 animals at the end of 2011 (MAGRAMA, 2012).

Nowadays, demand for autochthonous pig breeds products has increased, which is attributed to a revaluation of traditional, high-quality products. Therefore, the only option of survival of these breeds is relating to producing products with high added value. The Celta pig breed is characterized by a great rusticity that allows a perfect ability to adapt to the habitat conditions of the autochthonous forests. Among these last products we can find the “Lacón Gallego” which is manufactured from the foreleg of the pig, following a technology similar to that used for raw-cured ham and recognized as a Geographically Protected Identity (The Commission of the European Communities, 2001).

Quality in meat products have been defined as the total degree of satisfaction which the meat gives to the consumer (Jul and Zeuthen, 1981). On the other hand, the quality of dry-cured meat products is detected by the raw pieces and the manufacture process (Arnau et al., 2009). Some specific characteristics on fresh meat have been related with the quality of these products (Ruiz-Carrascal et al., 2000; Ruiz-Ramirez et al., 2006) like that the pig genotype (Armero et al., 2002; Garcia-Rey et al., 2004). Many parameters have been assessed to characterize dry-cured meat products such as color, texture, chemical composition (moisture, fat and protein content) and volatile compounds profile, which affects the quality of final product. Various studies have been carried out with the aim of improving the quality of dry cured lacón product. They have concerned the microbiological and biochemical (Lorenzo et al., 2007a, b; Lorenzo et al., 2008a, b; Garrido et al., 2012), sensorial properties (Purrinos et al., 2011b) and volatile compounds (Purrinos et al., 2011b) changes that take place during manufacture of the product. However any of these studies were carried out on pieces of Celta breed pig. Thus, the aim of this study was to determine the physico-chemical properties, lipolytic and proteolytic changes and volatile profile of dry-cured “lacón” from Celta pig breed.

MATERIALS AND METHODS

Experimental design and animal management: Ten pigs from the Celta breed (Barcina line) were used. All specimens, registered in the Record of Births of Stud-Book were obtained from ASOPORCEL. All animals were reared in a single group in an extensive system. They were fed ad libitum with commercial concentrate suited to the nutritive needs of the animals. Table 1 shows the chemical composition and fatty acid profile of the commercial feed. The animals were slaughtered at 12 months. The day before slaughter, the animals were weighed and transported to the abattoir trying to minimize the stress of the animals. Pigs were slaughtered in an accredited abattoir, using carbon dioxide to stun the animals (Lugo, Spain).

Samples: After the refrigeration period (24 h at 4°C), “lacón” samples were extracted. Fresh pieces of 4.35±0.09 kg were used. Raw pieces were salted with an excess of coarse salt. A heap was formed consisting of alternating layers of “lacón” pieces and layers of salt.

Table 1: Chemical composition and fatty acid profile of the commercial feed
The concentrate was formulated using the following ingredients (%): 40 wheat, 25.5% barley, 15% soybean flour, 14.6% corn, 1.5% soybean oil, 2% calcium carbonate, 1% dicalcium phosphate and 0.20% sodium chloride

In this way, the pieces were totally covered with salt and pieces remained in the pile for four days (a day per kg of weight), the temperature of the salting room was in the range 2-5°C and 80-90% relative humidity. After the salting stage, the pieces were taken from the pile, brushed, washed to remove salt excess and transferred to a post-salting chamber where they stayed for 14 days at 2-5°C and 85-90% relative humidity. After the post-salting stage the pieces were transferred to a room at 12°C and 74-78% relative humidity where drying-ripening took place for 84 days. The air convection in the drying room was intermittent and the air velocity around the pieces when the fan was running ranged between 0.3 and 0.6 m/s.

“Lacón” samples were taken from the fresh pieces, after the end of the salting stage, after 14 days of post-salting and after 84 days of drying-ripening. Each sample consisted of one whole “lacón” piece. In each sample point a total of five “lacón” samples were analyzed. Samples were transported to the laboratory under refrigerated conditions (<4°C) and analysed at this point. Once in the laboratory, the entire pieces were skinned, deboned and Triceps brachii muscle was extracted. The samples were stored at -80°C for no longer than four weeks until analysis.

Analytical methods
Reagents:
Fatty acid methyl esters (FAME’s) standard mixtures and nonadecanoic acid methyl ester were acquired from Supelco Inc. (Bellefonte, PA, USA). Analytical grade and liquid chromatographic grade chemicals were purchased from Merck Biosciences (Darmstadt, Germany). Boron trifluoride (14% solution in methanol) was obtained from Panreac (Castellar del Vallès, Barcelona, Spain). AccQ.Fluor reagent kit (AQC, borate buffer) and AccQ.Tag Eluent A concentrate were acquired from Waters (Milford, MA, USA). Acetonitrile (MeCN), disodium ethylenediaminetetraacetic acid (EDTA), phosphoric acid, sodium acetate trihydrate and sodium azide were from Baker (Phillipsburg, PA, USA); triethylamine (TEA) was purchased from Aldrich (Milwaukee, WI, USA). Amino acid standards, taurine and hydroxyproline were from Sigma (St. Louis, MO, USA).

pH, Water Activity, TBAR’S Values and Colour Parameters: The pH of samples was measured using a digital pH-meter (Thermo Orion 710 A+, Cambridgeshire, UK) equipped with a penetration probe. Colour measurements were carried out using a CR-600 colorimeter (Minolta Chroma Meter Measuring Head, Osaka, Japan). Each sausage was cut and the colour of the slices was measured three times for each analytical point. CIELAB space (CIE, 1976): lightness, (L*); redness, (a*); yellowness, (b*) were obtained. Before each series of measurements, the instrument was calibrated using a white ceramic tile. Lipid oxidation was assessed in triplicate by the 2-thiobarbituric acid (TBAR’S) method of Vyncke (1975) with the modification that samples were incubated at 96°C in a forced oven (Memmert UFP 600, Schwabach, Germany). Thiobarbituric acid reactive substances (TBAR’S) values were calculated from a standard curve of malonaldehyde (MDA) and expressed as mg MDA/kg sample. Water activity was determinated using a Fast-lab (Gbx, Romans sur Isére Cédex, France) water activity meter, previously calibrated with sodium chloride and potassium sulphate.

Chemical composition: Moisture, fat and protein (Kjeldahl N×6.25) and ash were quantified according to the ISO recommended standards 1442:1997 (ISO, 1997), 1443:1973 (ISO, 1973) and 937:1978 (ISO, 1978), respectively. Total chlorides were quantified according to the Carpentier-Vohlard official method.

WHC and texture analysis: Samples were cooked placing vacuum package bags in a water bath with automatic temperature control (JP Selecta, Precisdg, Barcelona, Spain) until they reached an internal temperature of 70°C, controlled by thermocouples type K (Comark, PK23M, UK), connected to a data logger (Comark Dilligence EVG, N3014, UK). After cooking, samples were cooled in a circulatory water bath set at 18°C during a period of 30 min. Cooking loss was calculated by measuring the differences in weight between the cooked and raw samples as follows:

Seven meat pieces of 1×1×2.5 cm (height × width × length) were removed parallel to the muscle fibre direction at a cross head speed of 3.33 mm/sec in a texture Analyzer (TA.XT.plus of Stable Micro Systems, Vienna Court, UK) and were completely cut using a Warner-Braztler (WB) shear blade with a triangular slot cutting edge (1 mm of thickness). Maximum shear force, shear firmness and total necessary work performed to cut the sample were obtained. Texture Profile Analysis (TPA) was measured by compressing to 60% with a compression probe of 19.85 cm2 of surface contact. Force-time curves were recorded at a cross head speed of 3.33 mm/s and recording speed was also 3.33 mm/s. Hardness (kg), cohesiveness, springiness (mm), gumminess (kg) and chewiness (kg*mm) were obtained. These parameters were obtained using the available computer software.

Free fatty acid: Total intramuscular lipids were extracted from 5 g of ground meat sample, according to Folch et al. (1957) procedure. Free fatty acids were separated using NH2-aminopropyl mini-columns as described by Garcia-Regueiro et al. (1994). Fifty milligrams of the extracted lipids were transesterified with a solution of boron trifluoride (14%) in methanol, as described by Carreau and Dubacq (1978) and the FAME’s were stored at -80°C until chromatographic analysis.

Separation and quantification of FAME’s was carried out using a gas chromatograph, GC-Agilent 6890N (Agilent Technologies Spain, S.L., Madrid, Spain) equipped with a flame ionization detector and an automatic sample injector HP 7683 and using a Supelco SPTM-2560 fused silica capillary column (100 m, 0.25 mm i.d., 0.2 μm film thickness, Supelco Inc, Bellafonte, PA, USA). Chromatographic conditions were as follows: initial oven temperature of 120°C (held for 5 min) , first ramp at 2°C/min to 170°C (held for 15 min), second ramp at 5°C/min to 200°C (held for 5 min) and third ramp at 2°C/min to final temperature of 235°C (held for 10 min). The injector and detector were maintained at 260 and 280°C respectively. Helium was used as carrier gas at a constant flow-rate of 1.1 mL min-1, with the column head pressure set at 35.56 psi. 1 μL of solution was injected in split mode (1:50). The fatty acids were quantified using nonadecanoic acid methyl ester at 0.3 mg mL-1, as internal standard, was added to samples prior to fat extraction and methylation. Identification of fatty acids was performed by comparison of the retention times with those of known fatty acids and the results expressed as mg g-1 of fat.

Free amino acids: The extraction of free amino acids was performed, as described by Alonso et al. (1994). The identification and quantification of amino acids were carried out used a HPLC Alliance 2695 model (Waters, Milford, USA) and 2475 scanning fluorescence detector (Waters Milford, USA). Empower 2TM advanced software (Waters, Milford, USA) was used to control system operation and results management.

The derivatization of standards and samples and chromatographic analysis conditions were as follow: 10 μL of sample was buffered to pH 8.8 (AccQ.Flour borate buffer) to yield a total volume of 100 μL. Derivatization was initiated by the addition of 20 μL of AccQ-Fluor reagent (3 mg mL-1 in acetonitrile). Reaction of the AQC with all primary and secondary amines was rapid and excess reagent was hydrolyzed within 1 min. Completion of hydrolysis of any tyrosine phenol modification was accelerated by heating for 10 min at 55°C. Separations were carried out using a Water AccQ-Tag column (3.9 mmx150 mm with a 4 μm of particle size) with a flow-ate of 1.0 mL min-1 and performed at 37°C. The gradient profile and composition of the mobile phase was adapted from methodology developed by Van Wandelen and Cohen, 1997. Detection was accomplished by fluorescence with excitation at 250 nm and emission at 395 nm. Amino acids were identified by retention time using an amino acid standard.

Analysis of volatile compounds: Samples were ground in a domestic blender and 10 g weighed, put into a dynamic headspace vial. The volatile compounds were extracted and concentrated in a purge and trap concentrator coupled with a cryofocusing module (Teledyne Tekmar, Mason, OH, USA).

Dynamic headspace volatile concentration: Samples were transferred into headspace vials and concentrated in a purge-and-trap concentrator (Stratum, Teledyne Tekmar, Mason, OH, USA) equipped with a cryofocusing module connected to an autosampler (Solatek 72 Multimatrix Vial Autosampler, Teledyne Tekmar, Mason, OH, USA). The sample was maintained at 60°C for 5 min and then flushed with helium at a flow rate of 60 mL min-1 for 20 min. Volatile compounds were adsorbed on a Tenax Trap (Strat trap, 30.48 cm, Agilent Technologies Spain, S.L., Madrid, Spain) and subsequently were thermally desorbed from the Tenax trap at 225°C for 4 min with a helium flow rate of 300 mL min-1. The desorbed compounds were cryofocused at -30°C using liquid nitrogen at the entrance of a DB-624 capillary column (JandW scientific, Folsom, CA, USA).

Gas Chromatography/Mass Spectrometry (GC/MS): A gas chromatograph 6890N (Agilent Technologies Spain, S.L., Madrid, Spain) equipped with mass detector 5973N (Agilent Technologies Spain, S.L., Madrid, Spain) was used with a DB-624 capillary column (JandW scientific: 30 mx0.25 mm id, 1.4 μm film thickness). The sample was injected in split mode (1:20). Helium was used as a carrier gas with a linear velocity of 36 cm/s. The temperature program used was as follows: 40°C maintained for 2 min and then raised from 40 to 100°C at 3°C/min, then from 100 to 180°C at 5°C/min and from 180 to 250°C at 9°C/min with a final holding time of 5 min; total run time 50.8 min. Injector and detector temperatures were set at 220 and 260°C, respectively.

The mass spectra were obtained using a mass selective detector working in electronic impact at 70 eV, with a multiplier voltage of 1953 V and collecting data at a rate of 6.34 scans/s over the range m/z 40-300. Compounds were identified comparing their mass spectra with those contained in the NIST05 (National Institute of Standards and Technology, Gaithersburg) library and/or by calculation of retention index relative to a series of standard alkanes (C5-C19) (Supelco 44585-U, Bellefonte, PA, USA) and matching them with data reported in literature. Samples were analyzed in triplicate. Results were reported as relative abundance expressed as total area counts (AUx106).

Statistical analysis: For the statistical analysis of the results of instrumental texture measurements, free fatty acid, free amino acid, volatile compounds and physico-chemical traits an analysis of variance (ANOVA) of one way using IBM SPSS Statistics 19.0 (IBM Corporation, Somers, NY, USA) was performed for all variables considered in the study. The Least Squares Mean (LSM) were separated using Duncan's t-test. All statistical test of LSM were performed for a significance level (p<0.05). Correlations between variables were determined by correlation analyses using the Pearson’s linear correlation coefficient with above statistical software package mentioned.

RESULTS AND DISCUSSION

Table 2 shows the physico-chemical properties, colour parameters and instrumental texture measurements through the manufacture process of dry-cured Celta “lacón”. Significant differences (p<0.001) during the whole of the manufacturing process were observed on pH values. An increase on final pH values in comparison with pH value of raw material (from 5.64 to 6.04) was found. Our final pH values were slightly lower than those reported by other authors (Marra et al., 1999; Lorenzo et al., 2003; Lorenzo et al., 2008b; Veiga et al., 2003) in dry-cured “lacón” and it is the same order those reported by Vestegaard et al. (2000) for dry-cured hams (5.5-6.2). According to these results, Celta “lacón” does not undergo true lactic fermentation and are in agreement with those found previously by others authors (Marra et al., 1999; Lorenzo et al., 2003). The increase on pH values through the manufacture process could be related with low-weight nitrogen molecules and ammonia formation ascribed to endogenous and exogenous proteolytic enzyme activities (Lucke, 1994; Virgili et al., 2007).

The mean moisture content observed in raw pieces (74.82%) is similar to the values found by other authors (Veiga et al., 2003). This content decreases progressively during the whole of the curing process being more pronounced during the last step. Our average final values (58.7%) were similar to observed by others authors (Veiga et al., 2003) in “lacón” samples with the same dry-ripening time than ours, while Lorenzo et al. (2008a) found final values below 50%.

Table 2: Evolution of physico-chemical parameters during the manufacture of dry-cured “lacón”, results expressed as means±standard error (n=5)
a-dMeans in the same row with different letters differ significantly (p<0.05, Duncan test) significance levels: *p<0.05, **p<0.01, ***p<0.001, n.s.: not significant

Pearson correlation test indicated that moisture contents were positively related to instrumental colour attributes of a* values (r = 0.60, p<0.01) and b* values (r = 0.68, p<0.01) and negatively correlated to pH (r = -0.83, p<0.01). In the same line, water activity gradually declined over the curing period from an initial value of 0.989 to 0.901 (p<0.001), on average (Table 2). This decrease, is due to the decrease of the water content, salt diffusion and the intense dehydration that the pieces undergo during the drying-ripening stage, in fact aw values showed a positive correlation with moisture content (r = 0.85, p<0.01) and a negative correlation with salt content (r = -0.95, p<0.01). The Pearson correlations indicated that aw was also related to the hardness (r = -0.74), gumminess (r = -0.67), chewiness (r = -0.71), L* values (r = 0.56), a* values (r = 0.62) and b* values (r = 0.59).

On the other hand, salt content (expressed as g/100 g of Total Solids) showed significantly (p<0.001) increased during the salting and post-salting stages as result of salt diffusion throughout the whole piece, reaching values that remained relatively constant until the end of the manufacture process (Table 2). The final mean values (15.63%) were higher than those reported by others authors for “lacón” (Marra et al., 1999; Lorenzo et al., 2008a; Veiga et al., 2003) who found values ranged 13 and 18.67 % of TS. However, Garrido et al. (2012) showed final average NaCl contents of 11.23, 12.22 and 12.75 g NaCl/100 g of TS in dry-cured “lacón” salted for 3, 4 and 5 days, respectively. Our sodium chloride values are found above of the range (5-9%) of those observed by other authors in other dry-cured meat products (Guerrero et al., 1999; Melgar et al., 1990). Intramuscular fat did not show significant differences (p>0.05) along the ripening process. Our mean values (4.50%) were lesser than those reported by other authors for dry cured “lacón” (Marra et al., 1999; Lorenzo et al., 2003). Several studies have showed different levels of intramuscular fat for Iberian ham (Petron et al., 2004; Ventanas et al., 2007), Serrano ham (Gandemer, 2009; Jimenez-Colmenero et al., 2010), Bayonne ham (Gandemer, 2009) and Parma ham (Lo Fiego et al., 2005). Gandemer (2009) and Ruiz-Carrascal et al. (2000) noticed that intramuscular fat content is the parameter that more affects the appearance, texture and flavor of dry-cured hams. A decrease in the protein content was observed during the manufacturing process, from an initial average value of 82.95 to 68.61% of TS at the end of ripening stage. This decrease appears to be fundamentally due to the increase in the NaCl content and decrease of moisture during the manufacture process.

A similar trend as in moisture profile was found in the water-holding capacity measured by Cooking Loss (CL). During the dry-ripening stage the CL was dramatically affected (p< 0.001) decreasing the value from 22.6 to 4.4%. The Pearson correlations indicated that CL was positively related to the a* values (r = 0.59, p<0.01), b* values (r = 0.65, p<0.01), aw (r = 0.80, p<0.01), moisture content (r = 0.96, p<0.01) and protein content (r = 84, p<0.01) and negatively related to the pH (r = -0.77, p<0.01), ClNa content (r = -0.79, p<0.01), hardness (r = -0.93, p<0.01), gumminess (r = -0.87, p<0.01) and chewiness (r = -0.91, p<0.01). The denaturation of meat protein caused decreases of the WHC (Gratacos-Cubarsi and Lametsch, 2008) and this led to water loss during the processing of dry-cured of “lacón”. Also, Alvarado and McKee (2007) noted that the irreversible reduction of protein functionality in meat related to the alteration of WHC may affect the rate of water lost from the meat including free, immobilized and bound water.

The degree of oxidation in the dry-cured “lacón” was measured by TBAR’S method which evaluates malonaldehyde formed in oxidation process. TBAR’S values increased significantly (p<0.001) during the salting stage and during the post-salting period from 0.18 to 0.98, 3.50 mg malonaldehyde/kg of muscular portion, respectively. The increase in malonaldehyde contents during the salting and post-salting stages was also reported by Garrido et al. (2009) in “lacón” samples and by Melgar et al. (1990) in hams. From these maximum values, a significant (p<0.001) drop was observed at the end of process reaching final average values of 2.60 mg MDA kg-1 of muscular portion. Our final values were the same order of those reported by other authors (Garrido et al., 2009; Veiga et al., 2003) in “lacón” samples and slightly lower than those observed by Rodriguez et al. (2001) and by Lorenzo et al. (2008b). This final drop was attributed to the instability of the malonaldehyde (Melgar et al., 1990).

The influence of ripening time on colorimetric characteristics is shown in Table 2. The luminosity (L*) values decreased during salting and post-salting stage from 38.7 to 33.2 and 31.8, respectively. These results are in agreement with those found by other authors (Marusic et al., 2011; Perez-Palacios et al., 2011) for dry-cured ham. This decrease was significantly correlated with aw (r = 0.55, p<0.05), protein content (r = 0.50, p<0.05) and ClNa content (r = -0.71, p<0.01). On the other hand, a* values showed a decrease during the post-salting stage and then remained constant until the end of process. This final value was similar to that described by Cava et al. (2003) for dry-cured loin and higher than those reported by Perez-Alvarez et al. (1999) Andres et al. (2000) for dry cured ham. Finally, yellowness values decreased as the time in process increased and this decrease was more pronounced during post-salting stage (p< 0.001). A similar pattern has been reported by Andres et al. (2000) for Iberian ham. These differences observed between dry-cured “lacón” and dry-cured ham could be due to the processing time, which is much shorter in the case of dry cured “lacón” with respect to the dry cured ham.

The parameters obtained from the Warner Bratzler (WB) shear test are presented in Table 2. Shear force showed a marked rise (p<0.001) from raw piece (3.80 kg/cm2) to the end of process (11.73 kg cm-2). This final value was higher than those reported by Guerrero et al. (1999) for dry-cured ham and by Ramirez and Cava (2007) for dry-cured loin. On the other hand, total work followed a similar trend showed the maximum values at the end of process of 55.23 kg*s. The texture profile of dry-cured Celta “lacón” (hardness, springiness, chewiness, gumminess and cohesiveness) was followed during the ripening period and results are given in Table 2. Hardness, chewiness and gumminess were affected by processing time (p<0.001) whereas springiness and cohesiveness did not show significant differences (p>0.05). Hardness increased (p<0.001) from 6.78 to 20.66 kg during ripening. Changes in hardness during dry-cured meat products ripening have been attributed to both water content and state of protein (Monin et al., 1997). It was found from Pearson correlation test that hardness was related (p<0.01) to pH, moisture content, aw, cooking loss and protein content with correlation coefficients of r = 0.85, r = -0.96, r = -0.74, r = -0.93 and r = 0.82, respectively. Moisture content, cooking loss and aw were negatively correlated to hardness so that decreasing moisture content, cooking loss and aw increased (p<0.01) hardness. Our results of hardness were higher than those reported by Guerrero et al. (1999) for dry-cured hams due that samples used for TPA analysis were cooked before analysis. On heat treatments at ambient pressure it is seen that there is an increase in hardness probably attributed to changes in the myofibrillar components of the muscle. In dry cured ham, texture is a characteristic directly related to the muscle structure, especially related to the degradation of myofibrillar protein and collagen as well as to the intramuscular fat content and drying rate (Toldra and Flores, 1998). Gumminess and chewiness values increased (p<0.001) from 4.84 to 11.86 kg and from 2.10 to 7.03 kg*mm during ripening period, respectively (Table 2), while cohesiveness and springiness did not show significant differences during the process. It was found from the Pearson test that moisture content and aw were related (p<0.01) to chewiness (r = -0.95 and r = -0.71, respectively) and gumminess (r = -0.92 and r = -0.67, respectively) values.

Changes of free fatty acid: The changes in the content of the different Free Fatty Acids (FFA) during the manufacture process of dry-cured Celta “lacón” are shown in Table 3. The total average content of FFA increased significantly (p<0.05), from 24.62 mg g-1 of fat in the raw pieces to 54.41 mg g-1 of fat at the end of the drying-ripening stage.

Table 3: Evolution of free fatty acids during the manufacture of dry-cured “lacón”, results expressed as means±standard error (n = 5)
Results expressed as mg g-1 of fat, a-dMeans in the same row with different letters differ significantly (p<0.05, Duncan test) Significance levels: *p<0.05, **p<0.01, ***p<0.001, n.s.: not significant PUFA = ∑ (C18:2n-6+C20:4n-6), MUFA =∑ (C18:1cis-9), SFA = ∑ (C16:0+C18:0)

Table 4: Evolution of free amino acids during the manufacture of dry-cured “lacón”, results expressed as means±standard error (n=5)
Results expressed as mg/100 g on the basis of dry matter, a-dMeans in the same row with different letters differ significantly (p<0.05, Duncan test), Significance levels: *p<0.05, **p<0.01, ***p<0.001, n.s.: not significant

It was reported that the amount of FFA increased in other meat products, during the processing, such as: dry-cured hams (Zhou and Zhao, 2007), dry-cured sausages (Navarro et al., 1997) and dry-cured loins (Hernandez et al., 1999). As the muscle enzyme systems play an important role in the generation of FFA (Motilva et al., 1992), the increase in the amounts of free fatty acids could be the result of the action of lipolytic enzymes.

The main FFA in the raw pieces were oleic acid (C18:1cis9), followed by linoleic (C18:2n-6) and palmitic (C16:0). This FFA profile is consistent with that reported by Veiga et al. (2003), Lorenzo et al. (2008b) for raw pieces of “lacón” and also with those showed by different authors for raw hams (Martin et al., 1999; Timon et al., 2002). As ripening time increase, an increase in oleic acid (from 7.14 to 19.13 mg g-1 of fat; p<0.001) and palmitic acid (from 7.11 to 14.67 mg g-1 of fat; p<0.001) was found. The greatest increase in levels of these FFA took place during the drying-ripening stage, which is consistent with the findings of Lorenzo et al. (2008b). A similar trend as in oleic acid was found in linoleic (C18:2n-6) and arachidonic (C20:4n-6) acids, which significantly increase (p<0.001) during the manufacture of dry-cured “lacón”. Increases in linoleic and arachidonic acid contents have also been described in other dry-cured meat products (Lorenzo et al., 2008b), although some authors (Martin et al., 1999) have observed a decrease in the contents of these acids.

The final amount of each individual fatty acid should be the result of the balance between its release from glycerides and phospholipids and its oxidative degradation. The main FFA at the end of the manufacturing process was oleic (C18:1cis9), followed by linoleic (C18:2n-6), palmitic acid (C16:0) and stearic (C18:0) (Table 3).This FFA profile is similar to that described by other authors for ham (Coutron-Gambotti et al., 1999; Martin et al., 1999) and dry-cured “lacón” (Lorenzo et al., 2008b).

Changes of free amino acid: Table 4 shows the evolution of Free Amino Acids (FAA) content during the manufacture of dry-cured “lacón”. These free amino acids have been usually identified when studying dry-cured ham (Ruiz et al., 1999; Toldra et al., 2000). Ornithine, which has a non-protein origin, has been previously reported in dry-cured ham (Toldra et al., 2000) but it was not identified in this study, which matches previous results in Iberian ham (Cordoba et al., 1994; Martins et al., 2001; Ruiz et al., 1999). Cysteine, a free amino acid coming from proteolysis, was detected, which disagrees with previous studies on dry-cured ham (Ruiz et al., 1999; Toldra et al., 2000).

A significant increase (p<0.001) on the total free amino acids was observed from raw pieces (688.6 mg/100 g of TS) to the end of dry-ripening (3309.9 mg/100 g of TS). These final contents were higher than those reported in previous studies (Lorenzo et al., 2008b; Garrido et al., 2012), who observed final values below 3000 mg/100 g of TS in dry-cured “lacón”. However, these final contents were lower than those reported by other authors (Monin et al., 1997; Ruiz et al., 1999; Virgili et al., 2007) for cured ham.

The increase in the individual free amino acids observed during the process was consistent with the increase in the total free amino acid content. This increase differed in the different amino acids: histidine, glycine, hydroxiproline, threonine and cysteine suffered the least increase; leucine, valine, isoleucine, tyrosine, phenylalanine, arginine, taurine, serine and alanine underwent moderate increases; and proline, aspartic acid, lysine, methionine and glutamic acid underwent the greatest increases. Cordoba et al. (1994) observed that in Iberian hams the free amino acids that underwent the greatest increases during the whole manufacture process were alanine and glutamic acid, followed by leucine, glycine and lysine, which is similar to the present findings. Schivazappa et al. (1995) reported that the quantity and type of free amino acids formed during manufacturing of ham depended on the activity of the aminopeptidases, cathepsins and muscle peptidases and of the NaCl content and the water activity values, variables that influence these enzymatic activities.

Arginine and taurine were the most abundant free amino acid found in raw pieces and are in disagreement with reported by Lorenzo et al. (2008b) who showed that the main free amino acid in the fresh pieces was glutamine, followed by taurine and alanine. The aminopeptidase activity is considered the main process implied in the FAA release in meat. However, the enzymatic activity is negatively affected by the relative increasing concentration of the salt occurring during drying and ripening due to water evaporation and, as a consequence, by the correspondent changes in the physico-chemical properties of the matrix (i.e., aw) (Garcia-Garrido et al., 2000).

The most abundant free amino acids detected in the final product were arginine, followed by taurine, glutamic acid and alanine, which were up to 270 mg/100 g of TS. This free amino acid profile differ with those observed in a previous study (Lorenzo et al., 2008b) where lysine, glutamic acid, γ-aminobutyric, glutamine and serien were the most abundant free amino acids at the end of the manufacturing process of dry-cured “lacón”.

Free amino acids constitute a potential source of volatile compounds as follows: (i) through Strecker degradation of valine (Val), isoleucine (Ile) and leucine (Leu), giving 2-methyl-propanal, 2-methyl-butanal and 3-methylbutanal, (ii) generation of dimethyl disulfide compounds from sulfur-containing amino acids, such as methionine, cysteine and cystine and (iii) the generation of a several pyrazines from Maillard reactions (Toldra et al., 2000).

Changes of volatile compounds: Sixty four volatile compounds were identified during the manufacture of dry-cured Celta “lacón” (Table 5) and classified into 10 chemical families (aldehydes, aromatic hydrocarbons, alcohols, esters, aliphatic hydrocarbons, furans, ketones, branched hydrocarbons, acids and other compounds). An increase in the total amount of volatile compounds was observed during the whole process, from an initial average value of 140.03x106 to 1932.70x106 area units (p<0.001) (Fig. 1). At the end of drying-ripening process the volatile compounds profile maintained the relationship esters > aliphatic hydrocarbons > branched hydrocarbons > alcohols > ketones > aldehydes > other compounds > aromatic hydrocarbons > furans > acids. These results are in agreement whit those reported by other authors (Barbieri et al., 1992; Bolzoni et al., 1996) who confirmed the esters as the family of compounds of highest percentage among the volatile components of Parma ham. In opposite, in other dry-cured hams (Gaspardo et al., 2008; Zhang et al., 2006) esters were found at low percentages. However, other authors (Huan et al., 2005; Purrinos et al., 2011a; Sanchez-Pena et al., 2005) reported aldehydes like the most abundant chemical family in different dry-cured meat products, while Gaspardo et al., 2008 concluded that alcohols family were the most abundant in “San Daniele” ham.

Esters showed a marked increase (p<0.001) during the curing process of dry-cured “lacón”, representing about 34.52% at the end of dry-ripening stage (Fig. 1). These compounds are formed by the esterification of carboxylic acids and alcohols. The enzymes involved in this reaction are esterase enzymes which are produced by different microorganisms (yeasts, moulds and bacteria) (Stahnke et al., 2002).

Fig. 1: Evolution of volatile compounds during the manufacture of dry-cured “lacón”

They can modulate the global flavour due to their low odour thresholds, imparting fruity notes (Marco et al., 2007). Among these compounds, the most abundant at the end of process was hexanoic acid, methyl ester, reaching values of 267.1x106 area units, followed by acetic acid, methyl ester and butnaoic acid, methyl ester, which represented around 83% of the total esters. Esters strongly affect the flavour of ham as typical aged meat products; in particular, the methyl branched short-chain esters were found to be positively related to the attribute of aged meat (Careri et al., 1993). The detection of ethyl esters, such as acetic acid, methyl ester and propanoic acid, methyl ester, could be explained by the esterification activity of staphylococci and lactic acid bacteria (Talon et al., 1998).

Aliphatic hydrocarbons increased significantly (p<0.001) from 40 to 423x106 area units during the whole process (Fig. 1). Significant differences were obtained for all aliphatic hydrocarbons detected during curing process (Table 5). Some authors (Ansorena et al., 2001; Ruiz et al., 2002) observed that aliphatic hydrocarbons with less than ten carbons atoms as pentane, hexane, heptane and octane were the most abundant at the end of process, which derive from lipid oxidation (Muriel et al., 2004), while those with longer chains could be accumulated in the fat depots of the animal, probably from feeding (Meynier et al., 1998). It was remarkable the high total value of aliphatic hydrocarbons at the end of the drying-ripening stage (21.89% of total chromatographic area). However, these results are not relevant due to hydrocarbons are not important contributors to the meat product flavour because of their high odour thresholds (Bianchi et al., 2007).

On the other hand, branched hydrocarbons were also detected at the end of process, representing about 15.57% of total chromatographic area (Fig. 1). Among these family, the most abundant was hexane, 2, 2,3- trimethyl, reaching values of 119.7x106 area units, followed by nonane, 3,7-dimethyl and nonane, 5-methyl, which represented around 69.4% of the total branched hydrocarbons. Regarding aromatic hydrocarbons, only two volatile compounds from this family were detected during the whole process (Table 5). Among these compounds, p-xylene was the most abundant, showed the highest amount at the end of process (30.56x106 area units). Animal feeding, particularly grass consumption (Ruiz et al., 1999) and the smoked process (Ansorena et al., 2001) have been reported as the most probable origins for aromatic hydrocarbons in dry-cured ham and dry-fermented sausages, respectively.

The most abundant ketones detected at the end of dry-ripening process was 2-pentanone following by 2-heptanone (38.31 and 21.34x106 area units, respectively).

Table 5: Evolution of volatile compounds (chromatographic peak area) during the manufacture of dry-cured “lacón”, results expressed as means±standard error (n=5)
LIR: Linear retention indexes, calculated in relation to the retention time of n-alkane (C5-C19) series, R: Reliability of identification: k: Kovats index in agreement with literature (Flores et al., 1997; Marco et al., 2007; Olivares et al., 2010; Lorenzo et al., 2012); m: mass spectrum agreed with mass database (NIST05); t: tentative identification by mass spectrum, a-dMeans in the same row with different letters differ significantly (p<0.05, Duncan test), Significance levels: *p<0.05, **p<0.01, ***p<0.001, n.s. = not significant

On the other hand, 2,3-butanedione and 2-butanone only appeared in the first stages of processing. 2-ketones have been abundantly isolated in dry cured products (Muriel et al., 2004; Purrinos et al., 2011a) and they are considered to have a great influence on the aroma of meat and meat products.

Regarding aldehydes showed a marked increase from the raw piece to the end of salting step decreasing thereafter at the end of the drying-ripening stage (p<0.001). The following compounds were identified: 3-methylbutanal, hexanal, heptanal, octanal, 2-octenal, 2-dodecanal and nonanal. Typical oxidation products of n-3 and n-6 PUFAs are aldehydes such as pentanal, hexanal and heptanal, which may exhibit green, fatty and soapy aroma notes when present above their odour threshold concentrations. Pentanal and hexanal can be formed from decomposition of hydroperoxides during autoxidation of n-3 and n-6 fatty acids, respectively (Olsen et al., 2005). These compounds present a low olfaction threshold and are thus largely responsible for the final aroma produced in dry-cured ham (Muriel et al., 2004; Ramirez and Cava (2007)). The majority compounds at the end of process were 3-methylbutanal (36.35x106 area units) and hexanal (13.11x106 area units). On the other hand, nonanal is a main oxidation product of oleic acid (Belitz et al., 2001), which was the most abundant unsaturated fatty acid (Table 3), but in our study we did not find any correlation between both.

Only 1-propanol has been detected in raw pieces. During the manufactured process a total of 6 news alcohols were found (Table 5). At the end of dry-ripening stage 1-pentanol was the most abundant, representing about 54% of the total alcohols. Among unsaturated alcohols, 1-octen-3-ol showed high values in the salting and post-salting stages (Table 5). Jurado et al., 2009 reported than this compound could serve as an indicator for an acorn diet. It derives from oxidation of arachidonic acid which is important in pork meat (Wood et al., 2004). The total area of alcohols increased throughout salting, decreasing slightly during post-salting and afterwards followed decreasing until the end of drying-ripening process (p<0.001) (Fig. 1). Alcohols have a low odour threshold, so they are important contributors to the aroma of these products (Sabio et al., 1998).

With respect acids family, only acetic acid was detected in every sample point. Some authors have reported that this acid is originated by the fermentation of sugars by microorganisms (Kandler, 1983) and other by the Maillard reaction (Martins et al., 2001). However, its importance in dry-cured ham may be limited, because this compound was not described as an odour-active compound of ham (Carrapiso et al., 2002). Finally, furans were not detected in the raw material. The highest amount this family was observed at the end of the post-salting stage (Fig. 1). Among furans, 2-penthylfuran was the most abundant at the end of process, it is a noncarboxylic compound derived from linoleic acid and other n-6 fatty acids (Frankel, 1991), with relatively low threshold and vegetable aromatic note (Fay and Brevard, 2005). Numerous authors (Huan et al., 2005; Ruiz et al., 1999) have reported 2-pentylfuran among the headspace volatiles of a wide variety of dry-cured hams.

CONCLUSIONS

During manufacture process of “lacón” took place some reactions of proteolysis and lipolysis which affect the characteristics of final product. As ripening time increased in dry-cured “lacón”, an increasing on TBAR’S values and hardness was observed. pH values showed a slight increase during the dry-ripening stage due to the formation of basic compounds probably as a result of proteolysis. FFA increased during the manufacture process, since oleic acid was the most abundant at the end of process followed by palmitic and linoleic.

In the final dry-cured “lacón”, esters were the richest chemical family among flavour substances, followed by aliphatic hydrocarbons and branched hydrocarbons. The most abundant volatile compound was hexanoic acid, methyl ester. Flavour formation of dry-cured “lacón” began from salting stage.

ACKNOWLEDGMENTS

Authors are grateful to Xunta de Galicia (Project FEADER 2010/15) for the financial support. Special thanks to ASOPORCEL for the lacón samples from Celta pig supplied for this research.

REFERENCES
Alonso, M.L., A.I. Alvarez and J. Zapico, 1994. Rapid analysis of free amino acids in infant foods. J. Liquid Chromatogr., 17: 4019-4030.
CrossRef  |  Direct Link  |  

Alvarado, C. and S. McKee, 2007. Marination to improve functional properties and safety of poultry meat. J. Appl. Poult. Res., 16: 113-120.
Direct Link  |  

Andres, A.I., J. Ruiz, A.I. Mayoral, J.F. Tejeda and R. Cava, 2000. Influence of rearing conditions and crossbreeding on muscle color in Iberian pigs. Food Sci. Technol. Int., 6: 315-321.
CrossRef  |  Direct Link  |  

Ansorena, D., O. Gimeno, I. Astiasaran and J. Bello, 2001. Analysis of volatile compounds by GC-MS of a dry fermented sausage: Chorizo de Pamplona. Food Res. Int., 34: 67-75.
CrossRef  |  Direct Link  |  

Armero, E., J.L. Navarro and M.I. Nadal, 2002. Lipid composition of pork muscle as affected by sire genetic type. J. Food Biochem., 26: 91-102.
CrossRef  |  

Arnau, J., X. Serra, J. Comaposada, I. Munoz, P. Picouet, E. Fulladosa and P. Gou, 2009. New technologies for dry-cured meat processing. Proceedings of International Congress of Meat Science Technology, Aug. 16-19, Copenhagen, Denmark, pp: 1-5.

Barbieri, G., L. Bolzoni, G. Parolari, R. Virgili, R. Buttini, M. Careri and A. Mangia, 1992. Flavor compounds of dry-cured ham. J. Agric. Food Chem., 40: 2389-2394.
CrossRef  |  Direct Link  |  

Belitz, H.D., W. Grosch and P. Schieberle, 2001. Changes in Acyl Lipids of Food. In: Food Chemistry, Belitz, H.D., W. Grosch and P. Schieberle (Eds.). 3rd Edn., Springer Verlag, Berlin, Heidelberg, New York, pp: 186-213.

Bianchi, F., C. Cantoni, M. Careri, L. Chiesa, M. Musci and A. Pinna, 2007. Characterization of the aromatic profile for the authentication and differentiation of typical Italian dry-sausages. Talanta, 72: 1552-1563.
CrossRef  |  PubMed  |  Direct Link  |  

Bolzoni, L., G. Barbieri and R. Virgili, 1996. Changes in volatile compounds of Parma ham during maturation. Meat Sci., 43: 301-310.
CrossRef  |  Direct Link  |  

CIE, 1976. Colorimetry: Official recommendations of the international commission on illumination. International Commission on Illumination, CIE No. 15 (E-1.3.1), Paris, France.

Careri, M., A. Mangia, G. Barbieri, L. Bolzoni, R. Virgili and G. Parolari, 1993. Sensory property relationships to chemical data of Italian-type dry-cured ham. J. Food Sci., 58: 968-972.

Carrapiso, A.I., J. Ventanas and C. Garcia, 2002. Characterization of the most odor-active compounds of Iberian ham headspace. J. Agric. Food Chem., 50: 1996-2000.
CrossRef  |  PubMed  |  Direct Link  |  

Carreau, J.P. and J.P. Dubacq, 1978. Adaptation of a macroscale method to the micro-scale for fatty acid methyl transesterification on biological lipid extracts. J. Chromatogr., 151: 384-390.

Cava, R., M. Estevez, J. Ruiz and D. Morcuende, 2003. Physico-chemical characteristics of three muscles from three muscles of free-range reared Iberian pigs slaughtered at 90 kg live weight. Meat Sci., 63: 533-541.
CrossRef  |  PubMed  |  Direct Link  |  

Cordoba, J.J., T. Antequera, J. Ventanas, C. Lopez-Bote, C. Garcia and M.A. Asensio, 1994. Hydrolysis and loss of extractability of proteins during ripening of Iberian ham. Meat Sci., 37: 217-227.
CrossRef  |  PubMed  |  Direct Link  |  

Coutron-Gambotti, C., G. Gandemer, S. Rousset, O. Maestrini and F. Casabianca, 1999. Reducing salt content of dry-cured ham: Effect on lipid composition and sensory attributes. Food Chem., 64: 13-19.
CrossRef  |  Direct Link  |  

Fay, L.B. and H. Brevard, 2005. Contribution of mass spectrometry to the study of the Maillard reaction in food. Mass Spectrom. Rev., 24: 487-507.
CrossRef  |  PubMed  |  Direct Link  |  

Flores, M., C.C. Grimm, F.A. Toldra and A.M. Spanier, 1997. Correlations of sensory and volatile compounds of Spanish Serrano dry-cured ham as a function of two processing times. J. Agric. Food Chem., 45: 2178-2186.
CrossRef  |  Direct Link  |  

Folch, J., M. Lees and G.H.S. Stanley, 1957. A simple method for the isolation and purification of total lipides from animal tissues. J. Biol. Chem., 226: 497-509.
PubMed  |  Direct Link  |  

Frankel, E.N., 1991. Review. Recent Advances in Lipid Oxidation. J. Sci. Food Agric., 54: 495-511.
CrossRef  |  Direct Link  |  

Gandemer, G., 2009. Dry cured ham quality as related to lipid quality of raw material and lipid changes during processing: A review. Grasas y Aceites, 60: 297-307.
Direct Link  |  

Garcia-Garrido, J., R. Quiles-Zafra, J. Tapiador and L. de Castro, 2000. Activity of cathepsin B, D, H and L in Spanish dry-cured ham of normal and defective texture. Meat Sci., 56: 1-6.
CrossRef  |  PubMed  |  Direct Link  |  

Garcia-Regueiro, J.A., J. Gilbert and I. Diaz, 1994. Determination of neutral lipids from subcutaneous fat of cured ham by capillary gas chromatography and liquid chromatography. J. Chromatogr., 667: 225-233.
CrossRef  |  PubMed  |  Direct Link  |  

Garcia-Rey, R.M., J.A. Garcia-Garrido, R. Quiles-Zafra, J. Tapiador and L. de Castro, 2004. Relationship between pH before salting and dry-cured ham quality. Meat Sci., 67: 625-632.
CrossRef  |  PubMed  |  Direct Link  |  

Garrido, R., R. Dominguez, I. Franco and J. Carballo, 2009. Lipolytic and oxidative changes during the manufacture of dry-cured lacon. Effect of the time of salting. Grasa y Aceites, 60: 255-261.
CrossRef  |  Direct Link  |  

Garrido, R., R. Dominguez, J.M. Lorenzo, I. Franco and J. Carballo, 2012. Effect of the length of salting time on the proteolytic changes in dry-cured lacon and on the sensory characteristics of the final product. Food Control, 25: 789-796.
CrossRef  |  Direct Link  |  

Gaspardo, B., G. Procida, B. Toso and B. Stefanon, 2008. Determination of volatile compounds in San Daniele ham using headspace GC-MS. Meat Sci., 80: 204-209.
CrossRef  |  

Guerrero, L., P. Gou and J. Arnau, 1999. The influence of meat pH on mechanical and sensory textural properties of dry-cured ham. Meat Sci., 52: 267-273.
CrossRef  |  

Hernandez, P., J.L. Navarro and F. Toldra, 1999. Lipolytic and oxidative changes in two Spanish pork loin products: Dry-cured loin and pickled-cured loin. Meat Sci., 51: 123-128.
CrossRef  |  

Huan, Y., G. Zhou, G. Zhao, X. Xu and Z. Peng, 2005. Changes in flavor compounds of dry-cured Chinese Jinhua ham during processing. Meat Sci., 71: 291-299.
CrossRef  |  

ISO, 1973. ISO 1443:1973: Meat and meat products-determination of total fat content. International Organization for Standardization, Geneva, Switzerland.

ISO, 1978. ISO 937:1978: Meat and meat products-determination of nitrogen content. International Organization for Standardization, Geneva, Switzerland.

ISO, 1997. ISO 1442:1997: Meat and meat products-determination of moisture content. International Organization for Standardization, Geneva, Switzerland.

Jimenez-Colmenero, F., J. Ventanas and F. Toldra, 2010. Nutritional composition of dry-cured ham and its role in a healthy diet. Meat Sci., 84: 585-593.
CrossRef  |  PubMed  |  

Jul, M. and P. Zeuthen, 1981. Quality of Pig Meat for Fresh Consumption. Pergamon Press, London, UK.

Jurado, A., A.I. Carrapiso, J. Ventanas and C. Garcia, 2009. Changes in SPME-extracted volatile compounds from Iberian ham during ripening. Grasas y Aceites, 60: 262-270.
CrossRef  |  

Kandler, O., 1983. Carbohydrate metabolism in lactic acid bacteria. Ant. V. Leuwenhoek, 49: 209-224.
CrossRef  |  PubMed  |  

Lo Fiego, D.P., P. Macchioni, P. Santoro, G. Pastorelli and C. Corino, 2005. Effect of dietary Conjugated Linoleic Acid (CLA) supplementation on CLA isomers content and fatty acid composition of dry-cured Parma ham. Meat Sci., 70: 285-291.
CrossRef  |  

Lorenzo, J.M., B. Prieto, J. Carballo and I. Franco, 2003. Compositional and degradative changes during the manufacture of dry-cured lacon. J. Sci. Food Agric., 83: 593-601.
CrossRef  |  

Lorenzo, J.M., M.C. Garcia Fontan, I. Franco and J. Carballo, 2007. Microbiological of dry-cured lacon. Fleischwirtschaft Int., 22: 88-92.

Lorenzo, J.M., M.C. Garcia Fontan, I. Franco and J. Carballo, 2008. Biochemical characteristics of dry-cured lacon (a Spanish traditional meat product) throughout the manufacture and sensorial properties of the final product. Effect of some additives. Food Control, 19: 1148-1158.
CrossRef  |  

Lorenzo, J.M., M.C. Garcia Fontan, I. Franco and J. Carballo, 2008. Proteolytic and lipolytic modifications during the manufacture of dry-cured lacon, a Spanish traditional meat product: Effect of some additives. Food Chem., 110: 137-149.
CrossRef  |  

Lorenzo, J.M., R. Montes, L. Purrinos and D. Franco, 2012. Effect of pork fat addition on the volatile compounds of foal dry-cured sausage. Meat Sci., 91: 506-512.
CrossRef  |  PubMed  |  

Lorenzo, J.M., S. Martinez, I. Franco and J. Carballo, 2007. Biogenic amine content during the manufacture of dry-cured lacon, a Spanish traditional meat product: Effect of some additives. Meat Sci., 77: 287-293.
CrossRef  |  

Lucke, F.K., 1994. Fermented meat products. Food Res. Int., 27: 299-307.
CrossRef  |  

MAGRAMA, 2012. Ministry of agriculture, food and environment. http://aplicaciones.magrama.es/arca-webapp/flujos.html?_flowId= razaPorcina-flowand_flowExecutionKey=e3s2.

Marco, A., J.L. Navarro and M. Flores, 2007. Quantitation of selected odor-active constituents in dry fermented sausages prepared with different curing salts. J. Agric. Food Chem., 55: 3058-3065.
CrossRef  |  

Marra, A.I., A. Salgado, B. Prieto and J. Carballo, 1999. Biochemical characteristics of dry-cured lacon. Food Chem., 67: 33-37.
CrossRef  |  

Martin, L., J.J. Cordoba, J. Ventanas and T. Antequera, 1999. Changes in intramuscular lipids during ripening of Iberian dry-cured ham. Meat Sci., 51: 129-134.
CrossRef  |  PubMed  |  

Martins, S.I.F.S., W.M.F. Jongen and M.A.J.S. van Boekel, 2001. A review of Maillard reaction in food and implications of kinetic modeling. Trends Food Sci. Technol., 11: 364-373.
CrossRef  |  

Marusic, N., M. Petrovic, S. Vidacek, T. Petrak and H. Medic, 2011. Characterization of traditional Istrian dry-cured ham by means of physical and chemical analyses and volatile compounds. Meat Sci., 88: 786-790.
CrossRef  |  PubMed  |  

Melgar, M.J., J.M. Sanchez-Monge and J. Bello, 1990. A study of the changes in the chemical properties of fat during ripening of dry Spanish sausage. J. Food Compos. Anal., 3: 73-80.
CrossRef  |  

Meynier, A., E. Novelli, R. Chizzolini, E. Zanardi and G. Gandemer, 1998. Volatile compounds of commercial Milano salami. Meat Sci., 51: 175-183.
CrossRef  |  PubMed  |  

Monin, G., P. Marinova, A. Talmant, J.F. Martin, M. Cornet, D. Lanore and F. Grasso, 1997. Chemical and structural changes in dry-cured hams (Bayonne hams) during processing and effects of the dehairing technique. Meat Sci., 47: 29-47.
CrossRef  |  PubMed  |  

Motilva, M.J., F. Toldra and J. Flores, 1992. Assay of lipase and esterase activities in fresh pork meat and dry-cured ham. Zeitschrift Lebensmittel Untersuchung Forschung, 195: 446-450.
CrossRef  |  Direct Link  |  

Muriel, E., T. Antequera, M.J. Petron, A.I. Andres and J. Ruiz, 2004. Volatile compounds in Iberian dry-cured loin. Meat Sci., 68: 391-400.
CrossRef  |  PubMed  |  

Navarro, J.L., M.I. Nadal, L. Izquierdo and J. Flores, 1997. Lipolysis in dry cured sausages as affected by processing conditions. Meat Sci., 45: 161-168.
PubMed  |  

Olivares, A., J.L. Navarro and M. Flores, 2010. Effect of fat content on aroma generation during processing of dry fermented sausages. Meat Sci., 87: 264-273.
CrossRef  |  PubMed  |  

Olsen, E., G. Vogt, A. Veberg, D. Ekeberg and A. Nilsson, 2005. Analysis of early lipid oxidation in smoked, comminuted pork or poultry sausages with spices. J. Agric. Food Chem., 53: 7448-7457.
CrossRef  |  PubMed  |  

Perez-Alvarez, J.A., M.E. Sayes-Barbare, J. Fernandez-Lopez and V. Aranda-Catala, 1999. Physicochemical characteristics of Spanish type dry-cured sausage. Food Res. Int., 32: 599-607.
CrossRef  |  Direct Link  |  

Perez-Palacios, T., J. Ruiz, D. Martin, J.M. Barat and T. Antequera, 2011. Pre-cure freezing effect on physicochemical, texture and sensory characteristics of Iberian ham. Food Sci. Technol. Int., 17: 127-133.
CrossRef  |  PubMed  |  

Petron, J.M., E. Muriel, M.L. Timon, L. Martin and T. Antequera, 2004. Fatty acids and triacylglycerols profiles from different types of Iberian dry-cured hams. Meat Sci., 68: 71-77.
CrossRef  |  PubMed  |  

Purrinos, L., R. Bermudez, D. Franco, J. Carballo and J.M. Lorenzo, 2011. Development of volatile compounds during the manufacture of dry-cured lacon a Spanish traditional meat product. J. Food Sci., 76: C89-C97.
CrossRef  |  PubMed  |  

Purrinos, L., R. Bermudez, S. Temperan, D. Franco, J. Carballo and J.M. Lorenzo, 2011. Influence of salt content and processing time on sensory characteristics of cooked lacon. Meat Sci., 87: 436-442.
CrossRef  |  PubMed  |  

Ramirez, M.R. and R. Cava, 2007. Effect of Iberian x Duroc genotype on dry-cured loin quality. Meat Sci., 76: 333-341.
CrossRef  |  PubMed  |  

Rodriguez, M.P., J. Carballo and M. Lopez, 2001. Characterization of the lipid fraction of some Galician (NW of Spain) traditional meat products. Grasas y Aceites, 52: 291-296.
CrossRef  |  Direct Link  |  

Ruiz, J., E. Muriel and J. Ventanas, 2002. The Flavour of Iberian Ham. In: Research Advances in the Quality of Meat and Meat Products, Toldra F. (Ed.). Research Signpost, Trivandrum, India, pp: 289-310.

Ruiz, J., J. Ventanas, R. Cava, A. Andres and C. Garcia, 1999. Volatile compounds of dry-cured Iberian ham as affected by the length of the curing process. Meat Sci., 52: 19-27.
CrossRef  |  PubMed  |  

Ruiz-Carrascal, J., J. Ventanas, R. Cava, A.I. Andres and C. Garcia, 2000. Texture and appearance of dry cured ham as affected by fat content and fatty acid composition. Food Res. Int., 33: 91-95.
CrossRef  |  Direct Link  |  

Ruiz-Ramirez, J., J. Arnau, X. Serra and P. Gou, 2006. Effect of pH24, NaCl content and proteolysis index on the relationship between water content and texture parameters in biceps femoris and semimembranosus muscles in dry cured ham. Meat Sci., 72: 185-194.

Sabio, E., M.C. Vidal-Aragon, M.J. Bernalte and J.L. Gata, 1998. Volatile compounds present in six types of dry-cured ham from south European countries. Food Chem., 61: 493-503.
CrossRef  |  Direct Link  |  

Sanchez-Pena, C.M., G. Luna, D.L. Garcia-Gomez and R. Aparicio, 2005. Characterization of French and Spanish dry-cured hams: Influence of the volatiles from the muscles and the subcutaneous fat quantified by SPME-GC. Meat Sci., 69: 635-645.
CrossRef  |  PubMed  |  

Schivazappa, C., G. Saccani, R. Virgili and C.S. Bordini, 1995. Evoluzione degli amminoacidi liberi durante la stagionatura del prosciutto crudo tipico. Ind. Conserve, 70: 377-385.
Direct Link  |  

Stahnke, L.H., A. Holck, A. Jensen, A. Nilsen and E. Zanardi, 2002. Maturity acceleration by Staphylococcus carnosus in fermented sausage-relationship between maturity and flavor compounds. J. Food Sci., 67: 1914-1921.
CrossRef  |  Direct Link  |  

Talon, R., C. Chastagnac, L. Vergnais, M.C. Montel and J.L. Berdague, 1998. Production of esters by Staphylococci. Int. J. Food Microbiol., 45: 143-150.
CrossRef  |  PubMed  |  

The Commission of the European Communities, 2001. Commission Regulation (EC) No. 898/2001 of 7 May 2001 supplementing the Annex to Regulation (EC) No. 2400/96 on the entry of certain names in the Register of protected designations of origin and protected geographical indications provided for in Council Regulation (EEC) No. 2081/92 on the protection of geographical indications and designations of origin for agricultural products and foodstuffs. Official J. Eur. Communit. L126, 44: 18-19.
Direct Link  |  

Timon, M.L., L. Martin, M.J. Petron, A. Jurado and C. Garcia, 2002. Composition of subcutaneous fat from dry-cured Iberian hams as influenced by pig feeding. J. Sci. Food Agric., 82: 186-191.
CrossRef  |  Direct Link  |  

Toldra, F. and M. Flores, 1998. The role of muscle protease and lipases in flavour development during the processing of dry-cured ham. Crit. Rev. Food Sci. Nutr., 38: 331-352.
CrossRef  |  Direct Link  |  

Toldra, F., M.C. Aristoy and M. Flores, 2000. Contribution of muscle aminopeptidases to flavor development in dry-cured ham. Food Res. Int., 33: 181-185.
CrossRef  |  Direct Link  |  

Van Wandelen, C. and S.A. Cohen, 1997. Using quaternary high-performance liquid chromatography eluent systems for separating 6-minoquinolyl-N-hydroxysuccinimidyl carbamate-derivatized amino acid mixtures. J. Chromatogr. A, 763: 11-22.
CrossRef  |  Direct Link  |  

Veiga, A., A. Cobos, C. Ros and O. DIaz, 2003. Chemical and fatty acid composition of Lacon gallego (dry-cured pork foreleg): Differences between external and internal muscles. J. Food Comp. Anal., 16: 121-132.
CrossRef  |  Direct Link  |  

Ventanas, S., J. Ruiz, C. Garcia and J. Ventanas, 2007. Preference and juiciness of Iberian dry-cured loin as affected by intramuscular fat content, crossbreeding and rearing system. Meat Sci., 77: 324-330.
CrossRef  |  Direct Link  |  

Vestegaard, C.S., C. Schivazappa and R. Virgili, 2000. Lipolysis in dry-cured ham maturation. Meat Sci., 55: 1-5.
CrossRef  |  Direct Link  |  

Virgili, R., G. Saccani, L. Gabba, E. Tanzi and C. Soresi Bordini, 2007. Changes of free amino acids and biogenic amines during extended ageing of Italian dry-cured ham. LWT-Food Sci. Technol., 40: 871-878.
CrossRef  |  Direct Link  |  

Vyncke, W., 1975. Evaluation of the direct thiobarbituric acid extraction method for determining oxidative rancidity in Mackerel (Scomber scombrus L.). Eur. J. Lipid Sci. Technol., 77: 239-240.
CrossRef  |  Direct Link  |  

Wood, J.D., R.I. Richardson, G.R. Nute, A.V. Fisher and M.M. Campo et al., 2004. Effects of fatty acids on meat quality: A review. Meat Sci., 66: 21-32.
CrossRef  |  PubMed  |  Direct Link  |  

Zhang, J., L. Wang, Y. Liu, J. Zhu and G. Zhou, 2006. Changes in the volatile flavour components of Jinhua ham during the traditional ageing process. Int. J. Food Sci. Technol., 41: 1033-1049.
CrossRef  |  Direct Link  |  

Zhou, G.H. and G.M. Zhao, 2007. Biochemical changes during processing of traditional Jinhua ham. Meat Sci., 77: 114-120.
CrossRef  |  Direct Link  |  

©  2019 Science Alert. All Rights Reserved