Juan Florencio Tejeda

Protein and lipid oxidation in Longissimus dorsi and dry cured loin from Iberian pigs as affected by crossbreeding and diet.

Lipid and protein oxidation in Longissimus dorsi (LD) and dry-cured loins from pigs with different genetic (pure Iberian (IBP), Iberian female×Duroc male (IB×D) and Duroc female×Iberian male (D×IB)) and feeding backgrounds (free rearing on acorn and pasture (MON), concentrates high in oleic acid and supplemented with 250ppm of vitamin E(HOVE) and control concentrates (CON)) were investigated. Diet influenced the fatty acids profile from PL and α- and γ-tocopherol contents of LD. IBP-MON pigs showed the lowest malonaldehyde (MDA) values at 200min of iron induced muscle oxidation. Dry-cured loins from IBP-HOVE pigs had significantly (p<0.05) higher values of TBARS than those from the other batches. Neither the diet nor crossbreeding affected hexanal counts in dry-cured loins. Protein carbonyl content showed a similar trend to that observed for MDA values in LD, suggesting a protective role of tocopherol against lipid and protein oxidation. The positive and significant correlations between iron induced lipid oxidation in LD (200 min) and carbonyl content in LD and dry-cured loin (R(2): 0.55 and R(2): 0.52, respectively, p<0.01) support the relationship between lipid and protein oxidation.

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).

Lipid traits of muscles as related to genotype and fattening diet in Iberian pigs: total intramuscular lipids and triacylglycerols.

Thirty pigs were allotted into four groups according to the fattening diet (Montanera, diet= acorns and pasture; and Pienso, diet=concentrated diet) and genotype (Iberian and Iberian×Duroc pigs). Lipid, fatty acid and triacylglycerol compositions,were measured in Biceps femoris muscle. Fattening diet largely affected muscle lipid composition. Total intramuscular lipid and triacylglycerol contents were higher in Montanera pigs than in Pienso pigs (8.0-8.1% vs 6.0-6.8% and 7.4-7.3% vs 6.2-5.4%, respectively). In Montanera pigs, triacylglycerols contained more oleic acid (54.7-56.8% vs 53.5-53.8% and less stearic and palmitic acids (8.8-8.4% vs 9.4-10.2% and 22.2-23.3 vs 23.7-24.4% respectively) and accordingly less PSO and more POL, POO and OOO(†) triacylglycerols compared to Pienso pigs (13.1-13.6% vs 16.2-19.2%, 4.4-3.5% vs 3.0-2.7%, 53.1% vs 51.3-51.9% and 10.1-12.3% vs 8.3-8.6%, respectively). Genotype had no effect on lipid and triacylglycerol contents of muscles and showed only a slight effect on fatty acid and triacylglycerol compositions.

Effect of free-range rearing and α-tocopherol and copper supplementation on fatty acid profiles and susceptibility to lipid oxidation of fresh meat from Iberian pigs.

The eAects of the feeding system (free-range versus confinement) and the inclusion in concentrate feeds of a-tocopheryl acetate (aTAc) (0.100 g kg ˇ1 ) and copper (II) sulphate (0.125 g kg ˇ1 ) or both on meat oxidative susceptibility, a-tocopherol, intramuscular lipid fraction fatty acid and volatile aldehyde contents were determined in Biceps femoris muscle from Iberian pigs. m. Biceps femoris from free-range-reared Iberian pigs showed a significantly higher oleic acid percentage in neutral lipids (p<0.001) than muscles from pigs fed in confinement, whereas confinement-pig muscles yielded higher arachidonic acid percentage (p<0.05) in intramuscular fat and linoleic acid percentage (p<0.05) in polar lipids. Copper (II) sulphate supplementation did not show any significant eAect on fatty acid composition of lipid fractions of the B. femoris muscle. a-TAc supplementation highly increased the a-tocopherol content of muscles (p<0.01). Free-range-reared pigs had the highest muscle FF61-tocopherol concentrations (p<0.001), reflecting the high content found in the pasture. Both free-range rearing and a-TAc supplementation reduced susceptibility to iron-ascorbate-induced peroxidation and reduced hexanal content (p<0.001). A clear relationship between the susceptibility to iron-ascorbate-induced peroxidation and the ratio between the concentration of polyunsaturated fatty acids inpolar lipids anda-tocopherol content was found.The present results suggest a beneficial eAect on meat quality when rearing hogs outdoors. They further suggest potential benefits to dry-cured products elaborated from free-range pigs as a result of a lower lipid oxidative trend of the meat. # 1999 Elsevier Science Ltd. All rights reserved.

Dry cured Iberian ham non-volatile components as affected by the length of the curing process

Free amino acids and peptides 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 reverse-phase HPLC. Most amino acids decreased from day 420 to day 600, whereas total peptide content and some of the individual peptides increased during this period. When analysing peptide extracts by HPLC coupled to an APCI-MS detector, peptides found showed a MW between 189 and 317. Partial least-squares regression of chemical and sensory data indicated that saltiness was related to salt content, whereas bitterness was related to some late-eluting peptides.

In situ transesterification of fatty acids from Iberian pig subcutaneous adipose tissue.

The purpose of this study was to optimize a rapid method for fatty acid analysis in Iberian pig subcutaneous adipose tissue. An in situ transesterification method was used to avoid the lengthy lipid extraction step. Samples were in situ transesterified with 5% HCl/methanol at 70°C, and toluene was used to help dissolve lipids. The method had advantages over other in situ methods since only 45 min were required to completely transesterify the fatty acids, and 10 min to obtain the fatty acid profile. A sample size of 25 mg of adipose tissue was suitable. The in situ transesterification gave higher fatty acid concentrations than conventional lipid extraction and transesterification, the differences being significant for all the fatty acids. Relative fatty acid contents were similar to those found by the conventional method.

Subcutaneous and intramuscular lipid traits as tools for classifying Iberian pigs as a function of their feeding background

The present work was aimed to study the feasibility of classifying Iberian pigs fattened with two different diets, acorns and grass (AG) and oleic acid enriched concentrate (HO), by means of comparing the fatty acid profile and the content of different compounds of the unsaponifiable lipid fraction (neophytadiene and α- and γ-tocopherol) of subcutaneous (SCF) and intramuscular (IMF) fat of Biceps femoris and Semimembranosus muscles. The proportions of palmitic (C16:0), stearic (C18:0) and linoleic (C18:2 n-6) acids of the three studied tissues did not show a consistent behaviour as influenced by the feeding. The proportion of oleic acid (C18:1 n-9) was significantly affected by the diet in SCF and IMF of Semimembranosus muscle but not in IMF of B. femoris. Some minor fatty acids, such as arachidonic (C20:4 n-6) and linolenic (C18:3 n-3) acids, showed the best ability for the classification of the animals according to their feeding background and the obtained values showed significant differences caused by the diet in the three studied tissues. Neophytadiene and γ-tocopherol contents were statistically higher in AG than in HO pigs, while there were not differences in the α-tocopherol levels between experimental groups. Thus, it seems that procedures based on the quantification of arachidonic (C20:4 n-6) and linoleic (C18:3 n-3) acids as well as neophytadiene and γ-tocopherol levels would be useful to differentiate Iberian pigs fattened outdoors on acorns and grass from those fed MUFA enriched diets.

Study of the branched hydrocarbon fraction of intramuscular lipids from Iberian fresh ham

Branched hydrocarbons from the unsaponifiable lipid fraction of intramuscular fat from Iberian dry-cured hams were analyzed. Thirty-four hams were distributed into four groups according to the feed system of the pigs (extensive system Montanera and intensive system Pienso) and genotype (Iberian and Iberian×Duroc). A total of 35 different hydrocarbons were identified in this study. Some differences were found in the levels of branched, cyclical and unsaturated hydrocarbons as a function of the diet of the pigs (3-hexyl-1,1-dimethyl cyclopentane, p<0.05; 3-octadecene, p<0.01; neophytadiene, p<0.001; 1-ethylundecyl benzene, p<0.01; cyclohexadecane, p<0.001; cyclotriacontane, p<0.05). However, the genotype had a limited effect in the level of branched hydrocarbons found. The study of branched hydrocarbons in intramuscular fat from dry-cured Iberian ham allows differentiation between the pigs management systems.

Influence of rearing conditions and crossbreeding on muscle color in Iberian pigs Influencia de las condiciones de crianza y del cruce en el color de los músculos de cerdos Ibéricos

The effects of pig crossbreeding (Iberian versus Iberian x Duroc 50%) and rearing conditions (out doors versus indoors) on muscle fiber composition, myoglobin content and objective muscle color in biceps femoris and tibialis crancalis muscles have been studied. Muscle fibers were identified as types I, IIA, IIB, oxidative IIB and IIC and the proportion of each fiber type was determined by a computer ized image analysis. Color co-ordinates L*, a*, and b* were measured and both chroma (C*) and hue angle (h°) were calculated. Myoglobin content and chroma value were significantly higher in tibialis cranealis muscle than in biceps femoris muscle (p ≤ 0.001), whereas the former muscle showed the lowest lightness and hue angle values (p ≤ 0.001). Moreover,tibialis cranealis muscle exhibited a higher total proportion of oxidative fibers, types I, IIA and IIBx (p ≤ 0.05), and a lower fat content than did biceps femoris muscle (p ≤ 0.001). The muscles of pigs reared outdoors tended to show a higher per centage of oxidative fibers (type I) than did muscles from indoor reared pigs, although not to a sig nificant extent. Rearing conditions significantly affected color, muscles from outdoor reared pigs ex hibiting higher lightness (L*), chroma (C*) and hue angle (h°) than muscles from indoor reared pigs. However, neither the crossbreeding nor the rearing conditions showed a significant influence on myoglobin concentration of muscles.