Sensory characteristics of Iberian dry-cured loins: Influence of crossbreeding and rearing system

The sensory characteristics of Iberian dry-cured loins and the influence of crossbreeding (pure Iberian - IB, Iberian female×Duroc male - IB×D and Duroc female×Iberian male - D×IB) and rearing system (outdoors fed on acorns and pasture - MON, indoors fed on concentrates high in oleic acid sunflower oil and supplemented with 250mg/kg of α-tocopherol acetate -HOVE- and indoors fed on control concentrates - CON) on sensory attributes were studied. Dry-cured loins from IB-MON and IB-HOVE pigs, which showed the highest intramuscular fat (IMF) content (p<0.01), reached higher scores for brightness, marbling traits (intensity, size and shape) and juiciness, and lower for hardness, dryness and fibrousness than loins from crossbred pigs (IB×D-HOVE, IB×D-CON and D×IB-HOVE). In fact, IMF content was positively linked to juiciness and marbling attributes and negatively to dryness, hardness and fibrousness, which was also observed in the principal component analysis (PCA). Neither the crossbreeding nor the rearing system seemed to influence odour, flavour and taste features. The PCA evidenced that dry-cured loins from IB-MON and IB-HOVE batches gathered together and were placed near to marbling attributes, juiciness and IMF content.     

Iberian ham headspace: odorants of intermuscular fat and differences with lean

The odorants from the intermuscular fat of Iberian ham were characterised for the first time and compared with those of the lean. A headspace extraction method and gas chromatography–olfactometry based on the detection frequency method were used. Compounds contributing to intermuscular fat odour were aldehydes (9), ketones (3), esters (2), nitrogen‐containing compounds (2), and one alcohol (1‐octen‐3‐ol). Eight odorants were identified for the first time as constituents of dry‐cured ham fat. The most potent odorants were hexanal and (Z)‐3‐hexenal, 3‐methylbutanal, 1‐octen‐3‐one and 1‐octen‐3‐ol and 2‐methylpropanal. Significant differences with odorants from the lean of the same hams were found; the largest differences appeared in sulfur‐containing compounds (specifically hydrogen sulfide, methanethiol and 2‐methyl‐3‐furanthiol), which seem not to contribute to fat odour but are some of the most potent odorants of lean. Significant and large differences were also found for other compounds such as 1‐octen‐3‐one and 1‐octen‐3‐ol, ethyl 2‐methylpropanoate, 2‐pentanone and 2,3‐butanedione. Copyright © 2004 Society of Chemical Industry     

Preference and juiciness of Iberian dry-cured loin as affected by intramuscular fat content, crossbreeding and rearing system

Preference ranking tests for juiciness and overall liking of dry cured loins from Iberian pigs with different genetic backgrounds (pure Iberian or crossbred Iberian×Duroc pigs), reared under different productive systems (outdoors on acorns and grass or indoors with mixed diets) and with different intramuscular fat (IMF) content, were conducted. IMF showed a positive influence on preference for juiciness and liking in subjects over 25 years of age, while younger consumers showed a similar trend for juiciness but not for preference. Loins from pure Iberian pigs showed significantly better ranking for juiciness and overall liking than those from crossbred pigs, even when the IMF content was similar. Dry cured loins from pigs reared outdoors and fed on acorns and pasture were ranked significantly better than those from animals fed indoors on concentrates, even though the mixed diets used were enriched in monounsaturated fatty acids and vitamin E in order to obtain meat with similar features to that of pigs reared outdoors, and despite very similar IMF contents. In conclusion, dry cured loins with high IMF content, from pure Iberian pigs and reared outdoors on acorns and grass attain the highest consumer preference.     

Proteomic analysis of semimembranosus and biceps femoris muscles from Bayonne dry-cured ham

The aim of the study was to delineate and compare the proteomic maps of two muscles of dry-cured ham: the biceps femoris and the semimembranosus. For this purpose, we used two-dimensional electrophoresis on a subcellular muscle fraction: insoluble protein in low ionic strength buffer. After protein identification by MALDI-TOF mass spectrometry and bioinformatic analyses, we found differences in expression levels in the two muscles. Seventy-three proteins or fragments were differentially expressed: 43 were over-represented in semimembranosus and 30 in biceps femoris. Although the study was performed on the insoluble protein fraction in low strength ionic buffer, protein and fragment identifications by mass spectrometry showed that most of the proteins were involved in energy metabolism. The differences observed between the two muscles can be explained by the differences in salt and moisture content in the course of dry-cured ham processing.     

Microwave oven application in the extraction of fat from the subcutaneous tissue of Iberian pig ham

The fat from subcutaneous tissue samples of Iberian pigs was extracted by solvent (2:1 chloroform-methanol) and by the action of microwave energy. The samples of liquid fat obtained by both extraction techniques were analysed by gas chromatography. Paired comparisons showed no significant differences in fatty acids in suggesting that the fat obtained by the two techniques was the same and that the extraction of fatty acids by microwaves is suitable for quality classification of Iberian pig carcasses.     

Effect of ripening time and rearing system on amino acid-related flavour compounds of Iberian ham

The evolution of free amino acids and amino acid-derived volatile compounds during the ripening of Iberian ham from pigs reared in a Montanera system (outdoor-based, with acorn and pasture available) and a Pienso system (indoor-based, with a high oleic acid concentrate) was studied. Ripening time influenced significantly all the free amino acids detected (p < 0.05) except for threonine and tyrosine. The total free amino acid content increased significantly from day 120 to day 230 (drying stage) and then the concentration remained almost steady. This marked increase in the free amino acid content matched an increase in the amino acid-derived volatile compounds. The volatile compounds also increased after day 230. Conversely, rearing system had a weak effect on the free amino acid content and on the amino acid-derived volatile compounds. Only glutamic acid was significantly influenced (p = 0.027), and a slight effect on proline and aspartic acid was found (p = 0.051 and p = 0.084, respectively), concentrations being larger in Montanera hams than in Pienso ones. With regard to the amino acid derived volatile compounds, only a significant influence of rearing system on acetaldehyde and on the coelution of 2,6-dimethylpyrazine+dihidro-2(3H)furanone was found. The small differences caused by rearing system confirm the great importance of concentrate formulation.     

Changes of arginyl and leucyl aminopeptidase activities in biceps femoris along Jinhua ham processing

Sixty experimental Jinhua hams were processed by a traditional method. The potential arginyl (RAP) and leucyl (LAP) aminopeptidase activities in biceps femoris were determined. The effects of temperature, salt content, sodium nitrate content and pH value on muscle RAP and LAP activities were evaluated using response surface methodology. Porcine muscle was found to possess very strong potential RAP and LAP activities that decreased gradually during processing from 165,980.97Ug(-1) and 89,201.52Ug(-1) before salting to 3164.70Ug(-1) and 5373.66Ug(-1) after aging, respectively. Temperature, pH value and salt content had significant effects on RAP and LAP activities (P<0.0001). They interacted with each other in their effects on RAP activity (P<0.0001) and influenced LAP activity in exponential way (P<0.05). However, 0-50mgL(-1) sodium nitrate had no detectable effect on either RAP or LAP activity (P>0.05). The regression models showed that muscle RAP and LAP maintained their activities all through Jinhua ham processing. LAP could display very strong actual activity during aging and post-aging, indicating that muscle LAP may play the most important role in generating free amino acids during the processing of Jinhua ham.     

n-Alkane content of intramuscular lipids of Iberian fresh ham from different feeding systems and crossbreeding

n-Alkane content of intramuscular lipids (Biceps femoris muscle) of the Iberian pig have been determined. Thirty-four pigs, divided into four groups, based in the feeding system (Montanera, fed on acorns and pasture; and Pienso, fed on a concentrate feed) and in the genotype (Iberian pure pigs; and Iberian crossbred with Duroc 50%) were studied. n-Alkane content of intramuscular lipids has not been affected by neither crossbreeding nor feeding, although the analysis of feeds administered to the pigs showed greater n-alkane values in pasture (consumed by animals in montanera), than in acorns and concentrate feed.     

Effect of the pig rearing system on the final volatile profile of Iberian dry-cured ham as detected by PTR-ToF-MS

The volatile compound profile of dry-cured Iberian ham lean and subcutaneous fat from pigs fattened outdoors on acorn and pasture (Montanera) or on high-oleic concentrated feed (Campo) was investigated by proton transfer reaction time-of-flight mass spectrometry. In addition to the usual proton transfer ionization the novel switchable reagent ions system was implemented which allows the use of different precursor ions (H₃O⁺, NO⁺ and O₂⁺). The analysis of the lean and subcutaneous fat volatile compounds allowed a good sample discrimination according to the diet. Differences were evident for several classes of compounds: in particular, Montanera hams showed higher concentrations of aldehydes and ketones and lower concentrations of sulfur-containing compounds compared to Campo hams. The use of NO⁺ as precursor ion confirmed the results obtained with H₃O⁺ in terms of classification capability and provides additional analytical insights.     

Sensory characteristics of Iberian ham: Influence of salt content and processing conditions

Sensory characteristics of Semimembranosus and Biceps femoris muscles from 24 dry-cured Iberian hams were assessed. Hams were salted with different amounts of salt (6% and 3% w/w) and then ripened at different temperature conditions (traditional processing vs. modified processing). Hams manufactured using modified processing showed higher scores for dryness (P<0.05), hardness (P<0.05) and rancid flavour (P<0.001) in the Semimembranosus muscle than those processed in a traditional way. The Biceps femoris muscle of hams salted with 6% of salt was drier (P<0.05), harder (P<0.05) and more fibrous (P<0.01) than in hams salted with 3% salt. Salty taste was more intense in the Semimembranosus and Biceps femoris from hams with a higher level of salt (P<0.01 and P<0.001, respectively). A more intense rancidity in hams ripened in modified processing could affect the overall aroma. A decrease in salt content produces less salty hams, but the changes in texture traits should be also considered.     

Changes of alanyl aminopeptidase activity and free amino acid contents in biceps femoris during processing of Jinhua ham

Sixty experimental Jinhua hams were processed by a traditional method. The potential alanyl aminopeptidase (AAP) activity in biceps femoris was determined. The effects of temperature, salt content, sodium nitrate content and pH on muscle AAP were evaluated using response surface methodology. Porcine muscle was found to possess very strong potential AAP activity that decreased gradually during processing from 201,635 U g⁻¹ before salting to 6147 U g⁻¹ after aging. Temperature, pH and salt content had significant exponential effects on AAP activity (P < 0.001). Both temperature and salt content interacted with pH in their effects on AAP activity (P < 0.01). However, 0–50 mg L⁻¹ sodium nitrate had no detectable effect on AAP activity (P > 0.05). The regression model showed muscle AAP maintaining its activity all through Jinhua ham processing, indicating that muscle AAP may generate free amino acids during the processing and storage of Jinhua ham. The concentrations of free amino acids increased significantly (P < 0.05) during Jinhua ham processing, except for arginine and cystine. The concentrations of most free amino acids were 5–20 times higher in the final product than in hams before salting. Final concentrations exceeded thresholds for sensory detection, thus implicating an important role of free amino acids in the determination of Jinhua ham flavor.     

Impact of high pressure treatment and intramuscular fat content on colour changes and protein and lipid oxidation in sliced and vacuum-packaged Iberian dry-cured ham

The effect of high hydrostatic pressure (HHP) (600 MPa) and intramuscular fat content (IMF) on colour parameters and oxidative stability of lipids and proteins in sliced vacuum-packaged Iberian dry-cured ham during refrigerated storage (120 days at 2 °C) was investigated. Several studies have investigated the influence of HHP on lipid oxidation of meat products. However, its effects on protein carbonylation, as also the influence of IMF content on this carbonylation are poorly understood. HHP treatment had a significant effect on lean lightness after 0 and 120 days of storage while IMF content increased lightness and yellowness over time. Regarding oxidative stability, the effect of HHP treatment depended on IMF content samples with a high IMF having greater lipid instability while samples with a low IMF underwent more protein carbonylation.     

High pressure treatment of dry-cured Iberian ham. Effect on radical formation,lipid oxidation and colour

The effect of high-pressure treatment (200, 400, 600 and 800 MPa) on radical formation in solid samples of dry-cured Iberian ham and in ham slurries was evaluated using the spin-trapping technique and electron spin resonance (ESR) spectroscopy. In addition, hexanal was, as a secondary lipid oxidation product, assessed by gas chromatography. The effect of pressure treatments on ESR signals determined in the spin-trapping assay following pressure treatment in solid samples of dry-cured Iberian ham was not statistically significant. However, the lowest level of pressure applied initiated radical formation and promoted lipid peroxidation, whereas intermediate to high levels of pressure seemed to promote further reaction and disappearance of free radicals. Pressure significantly affected hexanal content in the same way as seen for formation of free radicals. Regarding the slurries prepared from dry-cured ham, pressure significantly increased the tendency of radical formation as seen from the ESR signals and significantly increased the hexanal content. The different pattern between solid ham and ham slurries points toward an initiation mechanism associated with the membrane phospholipids for oxidation. In addition, surface colour (L*, a* and b* values and percent reflectance values) of non-pressurized and pressurized (200–800 MPa) dry-cured Iberian ham samples was assessed. Non-pressurized samples showed a higher lightness than pressurized samples, and redness significantly decreased with pressure treatment.     

The crossbreeding of different Duroc lines with the Iberian pig affects colour and oxidative stability of meat during storage

Colour and oxidative stability of Longissimus dorsi (LD) and Biceps femoris (BF) muscles from 3 different Iberian × Duroc genotypes (GEN1: ♂ Iberian × ♀ Duroc1, GEN2: ♂ Duroc1 × ♀ Iberian; GEN3: ♂ Duroc2 × ♀ Iberian) were analysed during 10 days of refrigerated storage. GEN1 and GEN2 are reciprocal crosses, while the difference between GEN2 and GEN3 is the Duroc sire line. The genotype Duroc1 was selected for the manufacture of dry-cured-meat products while the genotype Duroc2 was selected for meat production. BF showed more intense colour and oxidative changes during storage than LD, which is in accordance with their different metabolic pattern, since BF is an intermediate oxidative muscle whereas LD is a glycolytic one. Important differences were found between crosses due to the genotype of the Duroc sire line; however, reciprocal crosses (GEN1 and GEN2) showed a similar pattern. The lowest post-mortem pH of GEN3 could be a deciding factor of the oxidative and colour stability during storage as GEN3 had higher drip and cook loss as well as higher susceptibility to iron-ascorbate-induced oxidation. In addition, chops from GEN3 were paler (lower L^∗) and showed a higher discolouration (higher decrease of a^∗) besides higher lipid (TBA-RS) and protein oxidation (carbonyl content) after the storage.     

Ultrasonic and sensory characterization of dry-cured ham fat from Iberian pigs with different genetics and feeding backgrounds

The textural and ultrasonic properties of the subcutaneous fat from five batches of dry-cured hams from animals with different genetics (Iberian, Iberian×Duroc) and type of feeding ("montanera", concentrate feeds with different oleic acid content) were studied and related to the sensory traits (oiliness and brightness) of their biceps femoris muscle. The different genetics and feeding backgrounds found in the batches brought about differences in their ultrasonic velocities (average velocity from 4 to 20°C ranged from 1608 to 1650m/s) and textural parameters (maximum force at 8°C ranged from 11 to 21N). On average, batches with lower textural parameters had lower velocities and higher sensory scores. Ultrasonic measurements were used to carry out a discriminant analysis which allowed 78.3% of the samples to be correctly classified in the batches considered. Therefore, ultrasonic and sensory techniques could be useful in the characterization and differentiation of dry-cured hams from Iberian pigs.     

Prediction of lean and fat composition in swine carcasses from ham area measurements with image analysis

Video images of ham cross-sections were recorded from 71 pork carcasses (ranging in weight from 72 to 119 kg). Three sets of prediction equations were developed to estimate pork carcass lean and fat composition from video image analysis (VIA) of ham cross-sectional area measurements, 10th rib back fat depth (TENFAT) and hot carcass weight (HCKg). Carcass data of dissected lean and fat in the four primal cuts (ham, loin, Boston button and picnic shoulder) were used as dependent variables in establishing regression equations. The first set of equations combined VIA ham measurements and total ham weight (HTKg). Regression models containing the single variable HTKg times ham percentage lean area (Vol. 1) or HTKg times ham percentage fat area (Vol. 2) accounted for 88% and 68% of the variation in total carcass lean weight (CLKg) and total carcass fat weight (CFKg) from the right side of each carcass, respectively. The second set of equations combined VIA ham measurements and TENFAT (cm). Multiple regression models involving TENFAT, Vol. 1, and Vol. 2 accounted for 91% and 90% of the variation in CLKg and CFKg. The third set of equations used VIA ham measurements, TENFAT and HCKg. Carcass lean weight was best predicted by HCKg, TENFAT, and ham lean area (HLA) (R² = .92). Carcass fat weight was best predicted by HCKg, TENFAT, and Vol. 2 (R² = .91). Overall correlations showed a high association between Vol. 1 and CLKg (r = .94, P < .0001) and Vol. 2 and CFKg (r = .83, P < .0001). Ham lean area was related to CLKg (r = .74, P < .0001) and ham fat area to CFKg (r = .81, P < .0001). The results of this study indicated video image analysis of ham cross-section slices combined with backfat depth at the 10th rib can be used for accurate estimation of total carcass lean or fat composition.