Effect of solvent to sample ratio on total lipid extracted and fatty acid composition in meat products within different fat content.

The effect of solvent to sample ratio on total extracted lipids and fatty acid (FA) composition in meat products with different fat contents was evaluated. Total lipids were extracted according to the Folch et al. (1957) method, using a 20:1 ratio of chloroform:methanol (2:1, v/v) to sample (A), and also testing the solvent:sample ratio of 10:1 (B). Higher amounts of total lipids and total FA from neutral lipids were obtained using the A ratio, which could be due to an insufficient chloroform:dry-weight sample proportion which could be insufficient for solubilizing the total amount of lipids. In the polar lipid fraction, the total amount of FA was higher using the B rather than the A ratio, which may be caused by the higher volume of added water when using A than B. When studying the FA composition of different lipid fractions, the volume of both the solvent and the water for total lipid extraction should be considered.

Effect of brine thawing/salting on endogenous enzyme activity and sensory quality of Iberian dry-cured ham.

Simultaneous brine thawing/salting process was applied as an alternative to traditional pile salting process using 51 frozen Iberian hams. The effect of this type of salting process on endogenous enzyme activity and sensory quality of Iberian dry-cured hams was analysed. The frozen hams were simultaneously thawed and salted with saturated brine, with and without vacuum pulses, and were compared to hams thawed under refrigeration and traditionally salted. The peptidase and lipase activities were measured at the end of salting and post-salting stages. The activity of cathepsin B+L was reduced in the two brine salted batches while few differences among batches were observed for the other peptidases. Several lipase activities were significantly reduced in the two brine salted batches. The brine thawed processing affected the free fatty acid content at the different stages although the differences were more appreciated at the beginning of the process and no differences were observed at the end. The long ripening time makes these differences negligible and the consumer did not appreciate any differences between the sensory quality of Iberian brine/thawed hams and traditional Iberian thawed pile salted hams.

Pre-cure freezing effect on physicochemical, texture and sensory characteristics of Iberian ham.

The aim of this work was to investigate the effect of pre-cure freezing on the physicochemical, texture and sensory characteristics of raw and dry-cured hams. Both, refrigerated (R) and pre-cure frozen (F) hams showed the same weight losses during the processing. At the green stage F Iberian hams had lower moisture content, higher values of a* and chroma, lower hardness and chewiness and higher adhesiveness and springiness than R ones. However, at the end of the processing R and F Iberian hams only were different in salt content, F hams showing lower values than R ones. Sensory analysis of Iberian dry-cured ham did not show differences in salty taste. Panelist detected a higher fat hardness and lean pastiness in F than in R hams. The overall acceptability for both groups of dry-cured hams was between average and good.

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.

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.

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 Pearson's correlation showed any clear relationships between lipolytic changes and oxidative indices.

Study of the branched hydrocarbon fraction of intramuscular lipids from Iberian dry-cured 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.

Fatty acids and triacylglycerols profiles from different types of Iberian dry-cured hams.

Thirty hams were allotted into four groups according to fattening diet ("Montanera" - acorns and pasture; and "Pienso" - concentrated diet) and genotype of pigs (Iberian and Iberian×Duroc pigs). Total lipids, triacylglycerol composition and fatty acids from neutral lipids fraction were measured in biceps femoris muscle. Fattening diet largely affected lipid composition of hams. Total intramuscular lipids and triacylglycerols content were higher in Montanera hams than in Pienso hams. In Montanera hams, triacylglycerols contained more oleic acid (C18:1) and less stearic (C18:0) and palmitic (C16:0) acids (p<0.001) and accordingly less PSO, PPL, PPO, PPS, SSO (p<0.001) and more OLL, OOL, OOO triacylglycerols compared to Pienso hams (p<0.001). Genotype of pigs has an important effect in triacylglycerols composition but only a limited effect on their fatty acids composition. So, Iberian hams contained more of PLLn, PLL, POLn and POL+SLL compared to Iberian×Duroc hams (p<0.001) and POO and SOO were present in a higher quantity in Iberian×Duroc hams (p<0.01).

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).

Linear hydrocarbons content of intramuscular lipids of dry-cured Iberian ham.

This study has been carried out to determine the linear hydrocarbons content (n-alkane and n-alkene) in intramuscular lipids (biceps femoris muscle) of dry-cured Iberian ham considering "feeding system" (Montanera: fed on acorns and pasture and concentrate feed) and "genotype" (hams from Iberian pure pigs and hams from Iberian crossbreed with Duroc in a 50%). The linear hydrocarbons from n-C(14) to n-C(32) range were present in the four studied groups. n-Alkenes fraction (60-76 mg/kg of intramuscular fat) was higher than n-alkanes fraction (34-38 mg/kg). The most abundant n-alkane and n-alkene were the shortest chain ones. Feeding and genotype did not influence linear hydrocarbons content (neither n-alkanes nor n-alkenes).

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.

n-Alkane content of intramuscular lipids of Iberian fresh ham from different feeding systems and crossbreeding.

n-Alkane content of intramuscular lipids (Biceps femoris muscle) of the Iberian pig have been determined. Thirty-four pigs, divided into four groups, based in the feeding system (Montanera, fed on acorns and pasture; and Pienso, fed on a concentrate feed) and in the genotype (Iberian pure pigs; and Iberian crossbred with Duroc 50%) were studied. n-Alkane content of intramuscular lipids has not been affected by neither crossbreeding nor feeding, although the analysis of feeds administered to the pigs showed greater n-alkane values in pasture (consumed by animals in montanera), than in acorns and concentrate feed.

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

Branched hydrocarbons from the unsaponifiable lipid fraction of the Biceps femoris muscle of Iberian pigs were analyzed. Fifty-five Iberian pigs were distributed to seven groups according to management system (short Montanera and long Montanera, i.e. fed on acorn and pasture for 55 and 75 days prior to slaughter, respectively, and Pienso, fed on a concentrate diet), and genetic type. A branched hydrocarbon, neophytadiene, was identified only in samples from the pigs fed on the extensive system, with higher levels being found in pigs from the long Montanera group, than in those from the short Montanera group; this compound was not found in the Pienso group. Genotype did not affect the level of branched hydrocarbons found.

Free amino acids and other non-volatile compounds formed during processing of Iberian ham.

Fifty-five legs from Iberian pigs were traditionally processed into dry cured hams. Free amino acids and other non-volatile compounds in the water-soluble fraction from the biceps femoris muscle were analyzed by HPLC. At the drying stage and in the last months in the cellar the largest increases in these water-soluble compounds took place. There was a clear influence on free amino acid formation of salt content and on the formation of peptides of the temperature at each processing stage. As the amount of non-volatile compounds in the water-soluble fraction increases with processing time, their determination could provide a maturation index for Iberian ham.

Evolution of volatile aldehydes in Iberian ham matured under different processing conditions.

To evaluate the influence of the Iberian ham processing conditions in the evolution of volatile aldehydes, 35 hams were processed in two plants following different conditions of relative humidity and temperature. For this, free fatty acids, peroxide values and volatile aldehydes were quantified in the hams. The highest increases in free fatty acids were noted during the drying stage in both processing plants. The drying period also revealed the greatest increase in peroxide values, where the highest values were in those hams processed at higher temperatures. The temperature during post-salting and drying had a marked influence on the formation of volatile aldehydes, being responsible for the differences in volatile compounds of matured 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.

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. ©

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.

Prediction of the feeding background of Iberian pigs using the fatty acid profile of subcutaneous, muscle and hepatic fat.

Thirty Iberian pigs weighing 95 kg were randomly distributed into three groups of 10 animals each and fattened in three traditional management systems ['montanera' (MO), fed extensively on acorns, 'cebo' (CE) fed on a commercial diet and 'recebo' (RE), fed on acorns and a commercial diet]. Fatty acids from the Masseter muscle, lard and liver were analysed. In the lard, fatty acid profiles from MO and RE pigs presented minor differences; however, in the liver, RE pigs showed differences to MO pigs in most of the fatty acids studied. This suggests that the muscle and especially the liver fatty acid profile reflects the feeding regime during the last phase of feeding, while the lard reflects longer term differences.

Influence of finishing diet on fatty acid profiles of intramuscular lipids, triglycerides and phospholipids in muscles of the Iberian pig.

Thirty Iberian × Duroc pigs allotted in groups of ten animals were fed in three traditional different management systems ('Montanera' (MO), fed on acorns; 'Recebo' (RE), fed on acorns and a commercial diet; and 'Cebo' (CE), fed on a commercial diet). Masseter muscle was obtained to evaluate the influence of management system on fatty acid (FA) composition of lean. The FA composition of the intramuscular total lipids, triglyceride (TG) and phospholipid (PL) fractions was evaluated. Muscle from MO pigs had greater quantities of monounsaturated fatty acids (MUFA) in the total lipids, triglyceride and phospholipid fractions than the other feedings. The percentage of saturated fatty acids (SFA) of i.m. total lipids and TGs increased (P < .05) with duration of feeding on RE and CE, from 35.13-35.10% in MO pigs to 37.47-37.84% in RE pigs and 39.98-41.11% in CE pigs. PLs from RE and CE pigs contained more C(18:2) and C(20:4) and less C(18:1) than MO pigs.