Effect of Iberian × Duroc genotype on composition and sensory properties of dry‐cured ham

BACKGROUND: Dry‐cured ham quality from three different Iberian × Duroc genotypes was studied: GEN1, Iberian × Duroc1; GEN2, Duroc1 × Iberian; GEN3, Duroc2 × Iberian. GEN1 and GEN2 are reciprocal crosses, while the difference between GEN2 and GEN3 is the Duroc sire line. The line Duroc1 (DU1) was selected for the manufacture of dry‐cured meat products, whereas the line Duroc2 (DU2) was selected for meat production with low carcass fat. RESULTS: Dry‐cured hams from all genotypes had similar chemical composition. However, intramuscular fat of dry‐cured hams from GEN3 was more unsaturated than that from GEN2, while GEN1 was intermediate. Lipid oxidation, measured as 2‐thiobarbituric acid‐reactive substances (TBARS) and hexanal content, was similar between genotypes. The colour of hams was affected by genotype; hams from GEN2 showed higher lightness (CIE L*), while those from GEN3 had a less intense colour (lower a* and C*). Texture measured instrumentally did not differ between genotypes; however, in the sensory analysis, panellists considered hams from GEN3 more fibrous, while those from GEN2 were considered juicier. Hams from GEN3 were also perceived as saltier and more acid. CONCLUSION: Genotype affected the quality of Iberian hams, with those from GEN3 being of lower quality, and this genotype was considered less suitable for the manufacture of Iberian dry‐cured ham. Copyright © 2007 Society of Chemical Industry     

Effects of breed and age at slaughter on degradation of muscle lipids during processing of dry‐cured hams

Hams from Landrace, Duroc and Hampshire pigs slaughtered at ages 6, 7.5 and 9 months were processed to generate Norwegian Parma‐style hams. Lipid contents and the compositions of fatty acid classes (ΣSFA, ΣMUFA, ΣPUFA) within neutral lipids, phospholipids and free fatty acids were determined. Small differences in lipid degradation and composition of the classes were revealed. However, significant sensory differences related to lipids were observed. Breed was more important than age. Dry‐cured Hampshire hams gave a more intense mature odour that may be associated with higher overall lipid degradation. Unexpectedly, these hams also demonstrated high juiciness and tenderness, which could be related to the melting characteristics of the fat. Dry‐cured Duroc hams showed a higher susceptibility towards rancidity, presumably associated with preferential oxidation of n‐6 fatty acids relative to C18:1 n‐9. Dry‐cured Landrace hams showed the lowest juiciness and tenderness, likely due to their lower fat content (marbling).     

Influence of pre‐cure freezing on the profile of volatile compounds during the processing of Iberian hams

BACKGROUND: This work was designed to study the effect of pre‐cure freezing of raw thighs from Iberian pigs on the profile of volatile compounds during the processing of hams. RESULTS: Generation of volatile compounds during Iberian ham processing was similar in both pre‐cure frozen and refrigerated hams, the main differences being at the final stage. The levels of 2‐methylbutanal, 2‐methyl‐1‐butanol, 2,3‐butanediol and 2‐heptanol were significantly higher in dry‐cured hams that were pre‐cure frozen than in refrigerated ones, whereas the content of most detected esters was statistically lower in pre‐cure frozen than in refrigerated hams. CONCLUSION: The effect of pre‐cure freezing of Iberian ham on the profile of volatile compounds during ripening was not remarkable. Few differences were found in the final product, which would not greatly modify the aroma and flavour features of the dry‐cured hams. Copyright © 2010 Society of Chemical Industry     

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     

Optimisation of solid phase microextraction (SPME) for the analysis of volatile compounds in dry‐cured ham

Solid phase microextraction (SPME) has been shown to be an effective tool for analysing volatile compounds. The aim of this study was to optimise the conditions for the application of SPME in the analysis of volatile compounds in dry‐cured ham. The effects of exposure time and fibre coating were investigated while maintaining the dry‐cured ham at 30 °C to avoid artefact generation due to possible temperature effects. A divinylbenzene/Carboxen on polydimethylsiloxane (DVB/CAR/PDMS) coating showed the best extraction performance for medium‐ and high‐molecular‐weight analytes, whilst a Carboxen on polydimethylsiloxane (CAR/PDMS) coating gave the best results for low‐molecular‐weight compounds. A total of 70 different compounds were extracted by the two fibre coatings and identified. Sixty compounds were extracted by the DVB/CAR/PDMS fibre, whilst only 41 of these were found with the CAR/PDMS fibre. On the other hand, 10 additional volatile compounds were extracted by the CAR/PDMS coating, all of them being of low molecular weight. Two of the major compounds extracted, hexanal and 2‐pentanone, were found in high proportion in both fibre coatings. The extraction yields of dry‐cured ham volatile compounds varied according to the fibre coating used and the time of exposure. Therefore extraction conditions should be selected depending on the objective of the study. © 2002 Society of Chemical Industry     

Lipid degradation and sensory characteristics of M. biceps femoris in dry‐cured hams from Duroc using three different processing methods

Hams from Norwegian Duroc pigs, reared and fed identically, were dry‐cured using three different processing methods: Spanish Serrano (SS), Norwegian Parma‐style (PS) and deboning before curing (ND). The fatty acid compositions of the green and dry‐cured hams were analysed in terms of their neutral lipid, phospholipid and free fatty acid contents and correlated with sensory attributes. Although the three dry‐curing processes were quite different, the hams′ lipid profiles, lipid degradation patterns and lipid‐associated sensorial characteristics differed only slightly. The phospholipids were the most extensively degraded lipid class (88, 89% and 84% degradation in PS, SS and ND hams, respectively) for all processing methods. The SS and PS hams had slightly riper sensory profiles due to their extensive conversion of fatty acids into aroma components. The free fatty acid contents of PS, SS and ND hams were 6.3, 6.2 and 7.5 times greater than those of green hams, respectively.     

Comparison of simultaneous distillation extraction (SDE) and solid‐phase microextraction (SPME) for the analysis of volatile compounds in dry‐cured ham

Simultaneous distillation extraction (SDE) and solid‐phase microextraction (SPME) using a carboxen/polydimethylsiloxane fibre were compared for their effectiveness in the extraction of volatile compounds from dry‐cured ham samples. A higher number of compounds was detected using SPME owing to the use of a solvent delay time in the GC‐MS analysis of SDE extracts. SPME was more efficient in extracting low molecular weight and high volatility compounds, while SDE was able to extract compounds with low volatilities that were not extracted using SPME. Both techniques satisfactorily extracted most volatiles previously highlighted as odour‐active compounds in dry‐cured ham. However, the ratio between some compounds from lipid oxidation and those from degradation of amino acids was much lower in SDE extracts than with SPME, which could be a consequence of the development of Strecker degradation of amino acids during distillation in SDE owing to the high temperatures used. Similarly, diunsaturated aldehydes detected in SDE extracts were absent using SPME, probably owing to oxidation of polyunsaturated fatty acids in SDE as a consequence of the temperature during extraction. Copyright © 2004 Society of Chemical Industry     

Accumulation and evolution of tocopherols in dry-cured hams from Iberian pigs as affected by their feeding and rearing system

The influence of feeding and rearing systems on the accumulation and evolution of α- and γ-tocopherols in relation to storage time in dry-cured ham slices and pieces was investigated. The accumulation of γ-tocopherol in Musculus Biceps femoris or fat of cured hams was lower in groups fed acorns indoors than in those fed outdoors. However, these differences were not detected in M. Semimembranosus. Hams from pigs fed acorns had higher proportion of RRR-α-tocopherol stereoisomer and could also be used to discriminate the feeding background of the animals but not the rearing system. Loss in α- and γ-tocopherols of ham slices with storage was not affected by the rearing system but by the feeding. The discrimination between groups is better during the first 7 days of analysis. Loss in redness and yellowness was lower in ham slices from outdoor group which would indicate that exercise or other compounds provided by grass are also of interest in these quality parameters.     

Effect of prefreezing hams on endogenous enzyme activity during the processing of Iberian dry-cured hams

The use of frozen/thawed raw material in the processing of Iberian dry-cured ham has been studied to determine its effect on the sensory quality of the final product. The proteolysis and lipolysis processes were measured by the proteolytic and lipolytic enzyme activities and free amino acids and free fatty acids. The thawed Iberian hams had lower salt contents throughout the process. The use of thawing raw material did not affect the proteolytic enzymes, cathepsins, aminopeptidases and dipeptidylpeptidases, only the activity of dipeptidylpeptidase III was reduced due to thawing. Moreover, there were no differences in the content of free amino acids between fresh and thawed hams during the whole process. However, the use of thawing hams affected the lipolytic activity. The activity of phospholipase and neutral lipase were significantly higher in the thawed hams and also the content of free fatty acids, at all the stages analyzed. Consumer sensory analysis showed thawed Iberian hams had the lowest hardness, probably due to an intense proteolysis. The acceptability of the Iberian hams was similar between fresh and thawed hams.     

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.     

Effect of duration of the Montanera diet on the hydrocarbon fraction of intramuscular lipids from Iberian dry‐cured ham; characterization by gas chromatography

The characterization and differentiation of Iberian hams was studied as a function of the diet received by animals during the fattening period using a method based on hydrocarbon analysis. Thirty‐one hams were divided into three groups according to fattening diet (1, ‘Concentrate Feed’, fed on an intensive system with concentrates; 2, ‘Short Montanera’, fed on an extensive system with acorns and pasture for 50 days; and 3, ‘Long Montanera’, fed on an extensive system for 75 days). Saturated hydrocarbons in the n‐C₁₄ to n‐C₃₂ range and a large number of branched hydrocarbons were identified in the intramuscular fat of the three groups studied. The diet of the pigs during the fattening period did not affect the n‐alkane and n‐alkene content. The analysis of branched hydrocarbons revealed some significant differences relative to the type of diet. The ‘Concentrate Feed’ group had different concentrations of 2‐butyl‐1,1,3‐trimethylcyclohexane (P < 0.01), 3‐octadecene (P < 0.001), branched hydrocarbon 4 (P < 0.01) and neophytadiene (P < 0.001) than the ‘Montanera’ group. Copyright © 2006 Society of Chemical Industry     

Effect of IGF-II genotype and pig rearing system on the final characteristics of dry-cured Iberian hams

The effect of the IGF-II genotype (AG vs. GG) on the morphological and compositional parameters, the fatty acid composition of intramuscular fat, the odour concentration (analysed by dynamic olfactometry) and the volatile compound profile (analysed by proton transfer reaction time-of-flight mass spectrometry) of dry-cured Iberian ham was studied for the first time, and compared to the effect of pig rearing system (high-oleic concentrated feed vs. acorn and grass). The IGF-II genotype had no effect on most variables. However, it influenced the concentration of some odorants (methanethiol and octanal), although it did not affect odour concentration. Conversely, the rearing system had a significant effect on a large number of ham variables. Results indicate a negligible effect of the IGF-II genotype on the final ham quality and confirm that the rearing system has a marked effect.     

Proteolysis,protein oxidation and protease activity in dry‐cured Xuanwei ham during the salting stages

Twenty‐four experimental dry‐cured Xuanwei hams were salted using a standard method for 90 days. The proteolysis, protein oxidation and protease activities in biceps femoris (BF) and semimembranoesus (SM) muscles of dry‐cured Xuanwei ham were investigated during the salting phase. At the end of salting, the salt content increased to 35.2 g kg^?1 muscle in BF and 54.2 g kg^?1 muscle in SM. During the salting stage, salt soluble proteins were degraded mainly into water soluble proteins that were further broken down to peptides with molecular weights mostly greater than 1 kDa. Although large amounts of smaller peptides and free amino acids were generated, especially when the hams were aged. The carbonyl contents were increased but lower than 1.57 nmol mg^?1 proteins in muscles during the salting stage. The cathepsin B, dipeptidyl peptidase I (DPP I), alanyl (AAP), arginyl (RAP) and leucyl (LAP) aminopeptidase all remained active while salt content strongly inhibited cathepsin L and DPP IV in the first 90 days. The results suggested that the salting process promoted the hydrolysis of proteins, and increased the muscle protein oxidation at a slower rate.     

Effect of plant antioxidant in n‐3 polyunsaturated fatty acid–enriched diet on fatty acid composition and sensorial attributes of dry‐cured ham

Three groups of eight pigs (52.6–109.0 kg BW) were fed a high level of n‐3 polyunsaturated fatty acids (PUFA; L diet). Two cocktails of plant antioxidants were added separately to L diet (LAox1, LAox2). Fatty acid composition, lipoperoxidation and sensory evaluations were carried out on dry‐cured hams. No effect of dietary antioxidant was observed on total saturated, monounsaturated, n‐6 and total PUFA. Antioxidant supplementation significantly decreased the total n‐3 PUFA proportion in LAox1 and LAox2 products (6.75% and 7.08% of total FA, respectively) as compared to L (8.06%). However, C18:3n‐3 content of all products varied from 308 to 394 mg per 100 g without any dietary effect (P > 0.05). The supplementation with natural antioxidant significantly reduced the malondialdehyde content of dry‐cured ham (5.7–5.6 μg g^?1 for Laox1 and Laox2, respectively, vs. 10.2 μg g^?1 for L). Sensory evaluation of dry‐cured ham revealed no significant difference for all the tested attributes between treatments.     

Quality of Dry‐Cured Ham Compared with Quality of Dry‐Cured Shoulder

The physicochemical and sensory properties of 30 dry‐cured hams and 30 dry‐cured shoulders were analyzed to determine the relationships between them. The variables used to characterize both products were: compositional parameters, instrumental texture, amino acid and fatty acid composition, and sensory profile. Despite being products from the same animal and composed mainly of fat, lean, and bone, their morphological differences determine the conditions of the processing time, which produced differences between products in most of the parameters evaluated. Dry‐cured shoulders showed lower moisture content and greater instrumental hardness due to their morphology and muscular structure. Besides, these samples showed lower amino acid content according to the shorter ripening time. For the same reason, the dry‐cured hams showed higher moisture content, lower instrumental hardness, and higher amino acid content. However, the differences in the muscular structure did not affect the sensory characteristics, which were more related with some compositional parameters, such as chloride, moisture, and amino acid content and with the length of the curing process.