Elena Muriel

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.

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.

Comparison of different methods for total lipid quantification in meat and meat products.

This study was aimed to evaluate the efficiency of six extraction methods for the quantification of total lipid content in meat and meat products: standard Soxhlet method (with and without previous acid hydrolysis), continuous Soxhlet method (with and without previous acid hydrolysis), and those methods based in the use of a mixture of chloroform and methanol, and described by Folch, Less, and Sloane (1957) and Bligh and Dyer (1959). Lipid content was determined in nine different meat products with different fat contents and physico-chemical features: cooked turkey breast, fresh pork loin, cooked ham, dry-cured ham, mortadella, beef burger, fresh sausage, dry-cured sausage and salami. The most effective methods for determining fat content in the studied meat products were the method described by Folch et al. (1957) and the Soxhlet with previous acid hydrolysis method. The Soxhlet method without previous acid hydrolysis adequately extracted lipids only in those meat products with very high fat content. The use of the method described by Bligh and Dyer (1959) gave rise to the lowest lipid contents in all the studied meat products.

Free-range rearing increases (n-3) polyunsaturated fatty acids of neutral and polar lipids in swine muscles

This study was conducted to determine the effect of rearing pigs on a free-range system, on fatty acid profile of neutral and polar lipids from longissimus dorsi (LD) and masseter (MS) muscles, with special reference to n-3 polyunsaturated fatty acids (PUFA). Food sources for free-reared pigs were basically acorn and pasture, which were high in oleic and linolenic acids, respectively whereas, indoors, animals were fed a concentrate high in oleic acid. The predominantly oxidative MS muscle had lower saturated fatty acid (SFA) and higher PUFA contents than LD in neutral lipids (NL), and higher total n-3 PUFA and arachidonic acid contents and lower linoleic acid content in polar lipids (PL). Rearing the animals outdoors significantly increased total n-3 and n-6 PUFA of NL and total n-3 of PL. All n-3 fatty acids detected in PL were significantly higher in free reared animals, including eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids.

Short Note: Analyzing magnetic resonance images of Iberian pork loin to predict its sensorial characteristics

Iberian pork comes from genuinely bred Southwest Iberian Peninsula pigs traditionally fattened with acorns and pasture in an extensive production system. Dry-cured loins and hams constitute the main uncooked pork products with high sensorial quality and a first rate consumer acceptance, leading to high prices in the market. Several aspects related to quality in Iberian products have been examined by using chemical and sensorial procedures to provide quality. However, all these approaches are tedious and destroy the item. In addition, food science has shown little interest in MRI to explore meat products in a non-invasive way. Therefore, this paper introduce an objective and non-destructive methodology to classify Iberian loins consistently. It is based on texture analysis of MRI images displaying dry-cured pork loins. A statistical evaluation is provided for a set of 47 loins to predict three levels of different sensorial characteristics.

Meat quality characteristics in different lines of Iberian pigs

Physico-chemical parameters involved in technological meat quality for dry cured processing of four different lines (Entrepelado, Lampiño, Retinto and Torbiscal) of Iberian pigs were studied in the Masseter (MS) and Longissimus dorsi (LD) muscles. The line of Iberian pig significantly affected intramuscular fat content of MS muscle, animals from the Torbiscal line showing lower values. Proportions of several fatty acids of total lipids and polar lipids from the MS muscle were also affected. However, fatty acid composition and total lipids, neutral lipids and polar lipids of LD muscle and neutral lipids of MS muscle were scarcely affected. Lipid oxidation was also unaffected by Iberian pig line, but instrumental colour parameters of MS muscle showed significant variations.

Physico-Chemical and Sensory Characteristics of Dry-Cured Loin from Different Iberian Pig Lines:

The influence of the line of Iberian pigs (Entrepelado, Lampino, Retinto and Torbiscal) on dry-cured loin sensory traits and its relationship with several physico-chemical characteristics were analysed. Entrepelado and Lampino lines showed a higher intramuscular fat content (P 1/4 0.034). These lines reached the highest 0.010) and flavour (P 1/4 scores for brightness (P 1/4 0.005), odour intensity (P 1/4 0.043), marbling (P 1/4 0.017). Weight losses showed a positive relationship with some texture features, as hardness and dryness, and a negative one with juiciness according to the principal component analysis (PCA). Marbling was positively linked to odour intensity, juiciness and flavour intensity. These latter sensory traits have been previously linked to dry-cured meat products acceptability. Thus, dry-cured loins from Entrepelado and Lampino Iberian pigs seem to have better sensory profiles, mainly due to their more intense marbling.

Effect of dietary conjugated linoleic acid in combination with monounsaturated fatty acids on the meat composition and quality traits of dry-cured loin

Three levels (0%, 1% and 2%) of an enriched conjugated linoleic acid oil (CLA) were combined with two levels of monounsaturated fatty acids (MUFA) (low -19% average and high -39% average) for pig feeding. Composition, weight losses, lipid oxidation (thiobarbituric acid test, TBARs), change in the fatty acid content of the lipid fractions and sensory analysis of dry-cured loin as affected by dietary CLA, MUFA and CLA×MUFA interaction were studied. CLA and CLA×MUFA did not affect moisture and intramuscular fat content of dry-cured loin, weight losses during the processing, changes in the content of most fatty acids from lipid fractions and sensory traits. CLA and MUFA supplementation led to lower TBARs values (1.3mg MDA/kg sample for 0% CLA and 0.9mg MDA/kg sample for 2% CLA; 1.2mg MDA/kg sample for low MUFA diets and 0.9mg MDA/kg sample for high MUFA diets), the highest TBARs values being detected for 0% CLA-low MUFA diets [1.5mg MDA/kg sample]. The combination of dietary CLA with different MUFA levels in pig diets did not affect most composition and quality traits of dry-cured loin. Dietary CLA and MUFA seemed to lead to lower lipid oxidation in this product.

Lipolytic and oxidative changes in Iberian dry-cured loin.

This study was conducted using 61 Iberian pigs from four different genetic lines fattened under two different rearing systems. Fatty acid composition of neutral lipids (NL), polar lipids (PL) and free fatty acids (FFA) of the 61 fresh loins and their corresponding dry-cured loins and indices of lipid oxidation (hexanal, TBARS and rancid flavour) of the dry-cured loins were analyzed. Although the total amount of fatty acids from PL decreased most (89.77%), the fatty acid profile of FFA from dry-cured loin was more similar to that of NL from fresh loins. Monounsaturated fatty acids (MUFA) were the most abundant FFA type (260mg/100g muscle dry matter) followed by saturated fatty acid (SFA) (256mg/100g muscle dry matter) and polyunsaturated fatty acids (PUFA) (148mg/100g muscle dry matter). Neither genetic line nor rearing system showed any significant (P>0.05) effect on the decrease of fatty acids in the lipid fractions studied. The important decrease in PUFA from NL (43.70%) and PL (89%) was not reflected in higher oxidative indices in dry-cured loin. Neither PCA nor Pearsons correlation showed any clear relationships between lipolytic changes and oxidative indices.