A.I. Andrés

Volatile compounds of dry-cured Iberian ham as affected by the length of the curing process

Volatile compounds from 10 dry-cured Iberian hams ripened for two different processing times, a prolonged traditional one (600 days) and a shortened process (420 days), were analysed by purge and trap coupled to gas chromatography-mass spectroscopy. Eighty-three compounds were identified which agreed with the major classes found in other ham types. The amount of methyl branched alkanes was much higher than in other dry-cured ham types, probably due to the feeding regime. The percentages of 2- and 3-methylbutanal were higher (p<0.0001 and p<0.0003, respectively) in the longer aged hams, whereas the amounts of some compounds from lipid oxidation decreased from 420 to 600 days aging. In agreement with these observations, 600-day hams had higher scores for those odour and flavour traits usually considered to be positive attributes and lower scores for rancidity. A positive and significant correlation between 2-methyl butanal and cured flavour was found.

Influence of sensory characteristics on the acceptability of dry-cured ham.

The influence of different sensory attributes on the acceptability of dry-cured Iberian ham was studied. Partial least squares regression analysis showed that juiciness and several flavour traits were the major attributes positively influencing acceptability of dry-cured Iberian ham, whereas yellowness of the fat, dryness and fibrousness showed a negative influence. Using stepwise multivariate regression, juiciness and flavour intensity were the two traits that better explained the acceptability of dry-cured ham, the linear model obtained showing a regression coefficient of 0.526. The regression coefficient of acceptability with juiciness and flavour intensity was higher using a piecewise linear regression model (R(2)=0.759) showing, therefore, a discontinuous relationship between these variables. However, results on product acceptability have been obtained using trained panellists and it might be possible that the use of a consumer panel would change these conclusions.

Texture and appearance of dry cured ham as affected by fat content and fatty acid composition

Abstract The relationship between texture and appearance characteristics and the moisture, intramuscular fat (IMF) content and fatty acid composition of dry cured Iberian ham was studied using principal component analysis. Intramuscular fat content positively influenced the proportion of oleic acid ( R =0.5578), and exhibited a negative relationship with linoleic and arachidonic acids ( R =−0.5215 and −0.5770 respectively). IMF content also had a positive influence on some texture and appearance traits of ham, such as oiliness, brightness, juiciness and marbling. However, it was negatively related to dryness, fibrousness and hardness. Moisture displayed no relationship with juiciness, dryness or any other textural or appearance trait. Therefore, within the ranges of fat content and moisture found in the present study, IMF content has a stronger influence on the texture of ham than the degree of dehydration.

Volatile compounds in Iberian dry-cured loin

The volatile profile of Iberian dry-cured loin from four different Iberian pig lines (Entrepelado, Lampiño, Retinto and Torbiscal) and two feeding systems (OUT - fed on acorn and grass-vs.-IND - fed on high oleic acid concentrate) was studied using solid phase microextraction (SPME). 133 volatile compounds were identified and assigned to 16 chemical families. Alcohols were the major group, ethanol being the main compound. The high number of esters detected and the levels of ethanol and acetic acid found, points to an important role of microorganism activity in the formation of volatile compounds in Iberian dry-cured loin. Sulphur compounds, coming mostly from garlic, constituted an important group, with 14 compounds. Significant differences were found among loins from pigs reared in different feeding systems but not among Iberian pig lines. Dry-cured loins from OUT pigs showed higher levels of many compounds derived from lipid oxidation, such as octanoic acid (P=0.000), decanoic acid (P=0.018) or hexanal (P=0.014).

Lipid oxidative changes throughout the ripening of dry-cured Iberian hams with different salt contents and processing conditions

Hexanal content and TBARs were monitored in Semimembranosus and Biceps femoris muscles throughout the ripening of 46 dry-cured Iberian hams processed with different amounts of salt (6% vs. 3% w/w) and different processing systems (traditional vs. modified). Rancid odour and rancid flavour were sensorially analysed in the final product. Hams processed at higher temperatures during the drying stage, following a traditional system, showed lower values in this phase for hexanal content in both muscles (P 0.05). Evidently the effects of salt content and processing temperature, within studied ranges, on lipid oxidation are limited. In fact, increased processing temperature, during the drying stage, does not lead to greater oxidation in dry-cured ham, in spite of the well known pro-oxidant effect of temperature.

Oxidative stability and fatty acid composition of pig muscles as affected by rearing system, crossbreeding and metabolic type of muscle fibre.

Muscle fibre type, fatty acid composition of phospholipids (PLs) and triacylglycerols (TGs) and susceptibility of muscle to lipid oxidation were studied in Biceps femoris (BF) and Tibialis cranialis (TC) muscles from Iberian and Iberian×Duroc pigs reared indoors and outdoors. Fatty acid composition of TGs was not affected by muscle fibre type and crossbreeding, but was strongly influenced by rearing system. In PLs crossbreeding slightly affected monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid (PUFA) content in BF muscle, whereas rearing system showed a great influence on fatty acid composition of PLs. Oxidative fibres showed a positive relationship with saturated fatty acid (SFA) and MUFA contents and a negative one with PUFA content of PLs. Susceptibility of muscle to lipid oxidation was strongly influenced by diet, animals reared indoors and fed on concentrates showing higher levels of 2-thiobarbituric acid reactive substances (TBARS). Iberian×Duroc pigs tended to show slightly higher values of lipid oxidation than pure Iberian pigs. With regards to muscle fibre type, BF had lower TBARS values than TC, although within muscle no relationship was found between muscle fibre type and lipid oxidation.

Effect of live weight and sex on physico-chemical and sensorial characteristics of Merino lamb meat.

Forty-eight lamb carcasses were divided into four groups (n=12) according to slaughter weight (24 and 29kg) and sex (male and female). Colour, pH, moisture, and intramuscular fat were not affected (p>0.05) by slaughter weight or sex. With respect to fatty acid composition, slaughter weight had significant effects on C12:0 (p<0.01), C14:0, C16:0, and C18:1 n-9 (p<0.05) in Longissimus lumborum (LL) muscle. The percentage of C12:0 and C14:0 decreased as slaughter weight increased, while C16:0 increased. In Semimembranosus (SM) m., only C18:3 n-3 and C20:2 n-6 were affected (p<0.001) by slaughter weight. Total PUFA in LL m. was greater (p<0.01) in females than in males. Although in general, sensorial quality was not significantly affected by slaughter weight or sex, meat from lighter lambs (24kg) had greater general acceptability than meat from heavier lambs (29kg).

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.

Monitoring volatile compounds during dry-cured ham ripening by solid-phase microextraction coupled to a new direct-extraction device

Key flavour volatile compounds were monitored during ripening of dry-cured ham by solid-phase microextraction (SPME) coupled to a new direct-extraction device (DED). DED allows the insertion of the SPME fibre into the core of solid materials with no damage to the fibre. This enables extraction of volatiles from solid foodstuffs while avoiding sample handling. Major groups of volatile compounds extracted with SPME-DED agreed with available scientific literature about dry-cured ham volatiles. Moreover, volatile compounds previously highlighted as quality markers in dry-cured ham, such as 3-methylbutanal or hexanal, were satisfactorily extracted using SPME-DED. Changes in the profile of volatile compounds throughout the processing followed a typical pattern of volatile compounds formation. Therefore, SPME-DED appears as a new and promising method for monitoring ripening of dry-cured hams with no depreciation of the product, which might substitute traditional subjective methods currently used in the ham processing industry. However, the use of the internal standard method is not possible with this technique. Therefore, results using SPME-DED only point out a trend in the volatile profile. Further attempts relating data obtained using SPME-DED in dry-cured hams with sensory and chemical data from the same samples would be necessary for optimising this method as a quality control method in dry-cured ham industries.

Sensory characteristics of Iberian ham: Influence of rearing system and muscle location/ Caracteristicas sensoriales del jamón Ibérico: Influencia del sistema de engorde y del músculo

The effects of pig rearing conditions (free-range system based on acorn and pasture versus confinement on a concentrate feed) and muscle location (biceps femoris and semimembranosus) on sensory characteristics of dry-cured Iberian hams were studied. Muscle samples were sensorily evaluated for appearance, texture, aroma and flavor attributes by a trained panel. Muscle location significantly affected texture and appearance traits. Semimembranosus muscle was harder, dryer and more fibrous than was biceps femoris muscle. Rearing conditions significantly affected sensory attributes related to fatty acid composition and lipid content of meat. Hams from free-range pigs showed higher scores in oiliness, brightness of the lean, marbling, and aroma and flavor traits than did hams from pigs raised in confinement.