Teresa Antequera

Volatile components of dry cured Iberian ham

Abstract A study was conducted to identify the volatile compounds in aged Iberian hams, processed in the traditional way. The volatiles from aged hams were entrained in cold traps after distillation under high vacuum. The distillate was collected with dichloromethane and analysed by gas-chromatography-mass-spectrometry (GC-MS). Seventy-seven compounds were tentatively identified in the volatile fraction. Alkanes (12), branched alkanes (14), aldehydes (13), and aliphatic alcohols (9) dominated the volatiles. Small amounts of lactones (5), esters (9) and ketones (7) and other miscellaneous compounds were also present. The possible origins of these compounds and their relationship with the characteristic flavour of this product are discussed.

Lipid oxidative changes in the processing of Iberian pig hams

Attempts to identify the compounds responsible for the particular flavour of Iberian pig ham indicate that many derive from lipid oxidation. In the present work, the evolution of the degree of acidity, the peroxide value and the content of certain aldehydes was followed to assess the extent of the lipid oxidation in the Biceps femoris and Semimembranosus muscles of Iberian pig hams. Lipolysis occurs continuously throughout the process, being especially intense immediately after salting and during drying. The peroxide value was higher after salting and in the first stage in the cellar. Aldehyde content rose continuously in the first stages, but the sharpest rise took place before drying. Saturated aldehydes were more abundant than unsaturated. During the last stage, autoxidation seems to be considerably reduced.

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).

Effects of salt and temperature on proteolysis during ripening of Iberian ham

Fifty-five hams from Iberian pigs were processed using two different dry-curing techniques, traditional and modern. Salt content, non-protein nitrogen and its fractions (peptide, amino acid and volatile basic nitrogen) from Biceps femoris muscles were quantified. The existence of an overlapping effect of both temperature and salt content on the general non-protein nitrogen production was observed. The most intense proteolytic breakdown took place when higher temperatures were reached during the drying stage. The difference in salt concentration seems to contribute to generating different quantities in the non-protein nitrogen fractions. The inclusion at the end of the cellar stage of a stuffing period would permit increasing the accumulation of free amino acid in high salted hams.

Oxidative and lipolytic changes during ripening of Iberian hams as affected by feeding regime: extensive feeding and alpha-tocopheryl acetate supplementation.

The effect of pig feeding in an extensive system based on acorn and pasture or in confinement with a control diet containing 5 mg α-tocopheryl acetate kg(-1) of feed and a 100 mg α-tocopheryl acetate kg(-1) enriched diet on evolution of lipid changes throughout ripening of dry-cured hams was investigated. Feeding regime significantly affected TBA-RS, peroxide value and hexanal content of Biceps femoris and Semimembranosus muscles. Muscles from pigs fed supplemented diet with α-tocopherol or fed extensively on acorn and grass showed significant lower (p<0.05) TBA-RS and peroxide value than ham muscles from pigs fed the basal diet at 210 days of processing. Both feedings reduced significantly (p<0.05) hexanal content at day 210 and day 700. Muscle slices from pigs fed on acorn showed significant higher scores (p<0.05) in aroma and flavour intensity, cured flavour and numerically lower rancid scores than those from control diet hams. ©

Changes in intramuscular lipids during ripening of Iberian dry-cured ham

Thirty-one thighs were obtained from Iberian pigs fattened with acorns and were processed during 22 months in the traditional dry-curing process. Lipolysis affecting intramuscular fat during the processing of Iberian dry-cured ham has been analyzed by studying the changes of glycerides, phospholipids and free fatty acids in lipids from Biceps femoris muscle. Little change affected the fatty acid composition of glycerides during processing. A double-phased increase in the acidity values and a decrease in the quantity of fatty acids of phospholipids during the processing were observed. There seems to be a relationship between the extension of the lipolysis taking place during the maturing and the processing conditions and raw material used.

Hydrolysis and loss of extractability of proteins during ripening of iberian ham.

To elucidate the extent of the hydrolysis and loss of extractability of protein during the traditional ripening of Iberian ham, the evolution during processing of non-protein nitrogen (NPN) and protein fractions soluble in 0·03 m pH 7·1 phosphate and 1·1 KI + 0·1 m phosphate pH 7·4 buffers and 6 m urea was followed from Semimembranosus and Biceps femoris muscles. The NPN steadily increased during processing, showing maximum intensity at salting and drying. Electrophoretic study of the proteins extracted, and microscopical examination of the pellet obtained after consecutive extractions with the above buffers, revealed that hydrolysis and insolubilization are more intense in myofibrillar than in sarcoplasmic proteins. Protein aggregation involves mainly the myofibrillar fraction, and occurs during the first stage of processing.

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.

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.

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.