Nutritional and sensory quality of porcine raw meat, cooked ham and dry-cured shoulder as affected by dietary enrichment with docosahexaenoic acid (DHA) and α-tocopheryl acetate.

The effects of dietary enrichment of pig diets with DHA from a marine source (Algatrium(®)) and α-tocopheryl acetate on the nutritional and sensory characteristics of pork and pork products were evaluated. Raw and cooked hams, and dry-cured shoulders from pigs fed with three diets (control, control supplemented with 0.3% DHA plus 50ppm α-tocopheryl acetate and control with 200ppm α-tocopheryl acetate) were used. The treatments did not cause any significant differences in proteolytic and antioxidant enzyme activities, except on catalase (CAT) which increased significantly in raw hams from pigs fed DHA supplemented diets. Vitamin E accumulated in samples with α-tocopheryl acetate supplementation. DHA added to the diet increased the DHA level by 87% compared with the control treatment in both raw and dry-cured shoulders, and exceeded 82% in cooked hams. In consequence, the incorporation of the n-3 source in the diet significantly reduced the n-6/n-3 ratio in all products. The ratio reduction ranged from 51% in dry-cured shoulders to 65% in cooked and raw hams. No significant differences were found among treatments in the sensory parameters evaluated in the cooked hams. Fishy odour and flavour were not detected in any sample by the trained panel. However, reduced cured and aged flavours and a stronger fishy flavour were found in dry-cured shoulders from pigs on the DHA enriched treatment; while, α-tocopheryl acetate supplementation had negligible influence on flavour.

High pressure applied to frozen ham at different process stages. 1. Effect on the final physicochemical parameters and on the antioxidant and proteolytic enzyme activities of dry-cured ham.

This paper describes the effect of high pressure (400MPa and 600MPa) applied to frozen hams at early stages of the dry-cured ham process: green hams (GH) and hams at the end of the resting stage (ERS), on some physicochemical parameters and on antioxidant and proteolytic enzyme activities in the final product. No significant differences were observed among treatments either in the drying kinetics or in the physicochemical characteristics. However, when high-pressure was applied to frozen GH hams it produced a superficial denaturation that affected salt absorption and, consequently, the proteolysis index. The high-pressure treatment applied during the processing of previously frozen GH and ERS hams reduced the antioxidant enzyme activities slightly (superoxide dismutase, catalase and glutathione peroxidase) but did not affect the cathepsin B and the cathepsin B+L activities.

High pressure applied to frozen ham at different process stages. 2. Effect on the sensory attributes and on the colour characteristics of dry-cured ham.

This paper describes the effect of high pressure (400MPa and 600MPa) applied to frozen hams at early stages of the dry-cured ham process: green hams (GH) and hams at the end of the resting stage (ERS), on the appearance, some texture and flavour parameters and on the instrumental colour characteristics of dry-cured hams. Pressurized hams showed slightly lower visual colour intensity than the control ones. In general, pressurization did not have a significant effect on the flavour characteristics of the final product. The 600-MPa hams from the ERS process showed significantly lower crumbliness and higher fibrousness scores than the control and the 400-MPa hams. However, none of these differences were enough to affect the overall sensory quality of the hams negatively. Regarding instrumental colour characteristics (L(∗)a(∗)b(∗)), an increase in lightness was observed in the biceps femoris muscle from GH hams pressurized at 400MPa and 600MPa but not in the ERS hams.

Quality pork genes and meat production.

Functional genomics, including analysis of the transcriptome and proteome, provides new opportunities for understanding the molecular processes in muscle and how these influence its conversion to meat. The Quality Pork Genes project was established to identify genes associated with variation in different aspects of raw material (muscle) quality and to then develop genetic tools that could be utilized to improve this quality. DNA polymorphisms identified in the porcine PRKAG3 and CAST genes illustrate the impact that such tools can have in improving meat quality. The resources developed in Quality Pork Genes provide the basis for identifying more of these tools.

Glutathione peroxidase activity, TBARS, and alpha-tocopherol in meat from chickens fed different diets.

This study investigated the effect of feeding broilers with diets differing in dietary fat source (lard, sunflower oil, olive oil) and vitamin E (basal vs supplemented with 200 mg of alpha-tocopheryl acetate/kg) on meat lipid oxidative stability. The diets differed by their degree of unsaturation and included the natural antioxidant alpha-tocopherol (vitamin E). Glutathione peroxidase (GSHPx) activity was measured in raw meat and ranged from 3.62 to 8.06 nmol NADPH/min/mg protein. The enzyme activity was influenced by the degree of unsaturation of the diet. Capillary gas chromatography analyses showed that dietary alpha-tocopherol accumulated in the muscle tissue and contributed to a better oxidative stability of the raw and cooked meat. Thigh meat alpha-tocopherol levels ranged from 2.73 to 3.62 microg/g in unsupplemented chickens whereas levels from 8.69 to 13.37 microg/g were observed in the thigh meat from alpha-tocopherol supplemented animals. The inclusion of olive oil and alpha-tocopherol in the animal diet gave lower thiobarbituric acid reactive substance (TBARS) values and lower GSHPx activity. High correlations were found between the parameters studied. The results suggest that the glutathione peroxidase activity could be used as an indicator of the meat oxidative stability. A negative relationship was observed between GSHPx activity and tissue alpha-tocopherol levels, and a positive relationship was evidenced between TBARS and antioxidant enzyme activity.

Oxidation of microsomal fraction in the processing conditions of dry-cured ham. The in-vitro effect of brine.

Throughout the manufacturing process of dry-cured ham intense lipid oxidation occurs. Muscle microsomal membranes were used as a model of muscle oxidation in three different procedures: (i) enzymic reaction; (ii) nonenzymic reaction and (iii) sarcoplasmic proteins and microsomal fraction interaction. Porcine M. Biceps femoris from normal and PSE meat qualities treated with 3% NaCl at different temperatures was used as a model of the dry-cured ham process. M. Biceps femoris from normal porcine meat was used to study the in-vitro effect of brine in the oxidative processes. Results showed an important increase of MDA concentration in enzymic and nonenzymic reactions and a higher than normal oxidation level in PSE meat in samples aged for 6 days at 4 °C. The in-vitro assays showed a high level of nonenzymic lipid oxidation at 3 °C incubation. On the other hand, the enzymic reaction showed greater values of MDA at 20 °C incubation. In-vitro NaCl concentrations seemed to have an antioxidant effect in these conditions. Sarcoplasmic proteins had little effect on the oxidative mechanisms suggesting a lack of interaction of these proteins with the microsomal fraction.

The effect of meat quality, salt and ageing time on biochemical parameters of dry-cured Longissimus dorsi muscle.

Pieces of Longissimus muscle were used as models of dry-cured ham to study the effect of NaCl concentration, meat quality and ageing time on the biochemical parameters related to the ham curing process. Higher amounts of added salt did not result in an increase in the protein extractibility. The activity of the lysosomal enzymes cathepsins D and B showed dependence on the ageing time, whereas cathepsin B and cathepsin B+L activities depended on meat quality. Cathepsin B+L activity increased with the addition of salt. Meat quality had an influence on all the parameters studied except on MFI, on cathepsin D activity and on the inhibitory activity on cathepsin B. Two protein bands likely to correspond to titin and nebulin were detected in the pherograms of myofibrillar proteins of muscle even those aged for as much as 48 h and irrespective of meat quality. Titin was also found in the sarcoplasmic protein fraction of salted samples from N and DFD meat, but not from PSE meat.

Membrane lipid oxidation and proteolytic activity in thigh muscles from broilers fed different diets.

The effects of diets differing in their level of unsaturation and their contents of natural antioxidants and prooxidants on lipid oxidation was measured in microsomal membranes of the thigh muscles of broilers by three processes: enzymatic, nonenzymatic and sarcoplasmic protein oxidation. Lysosomal cysteine proteinase activities were determined to assess the influence of the different diets on the enzymatic proteolysis of meat. Statistically significant differences were found in the enzymatic reaction for 72 h of incubation at 4°C in relation to the effect of both diet and antioxidant supplementation. Meat from animals fed an unsaturated diet containing sunflower oil gave the highest level of oxidation. Broilers fed supplemental antioxidants, especially α-tocopherol, had lower degrees of oxidation than those fed the basal diet. An unexpected result of the prooxidant diet study was a higher degree of oxidation in samples from animals deprived of iron and copper. Cysteine proteinase activities were favoured by vitamin E (α-tocopherol) supplementation and the absence of copper. ©

Effect of curing salt and phosphate on the activity of porcine muscle proteases.

The effect of curing salt on the activity of porcine muscle proteases was evaluated, within the salt concentration range found in the manufacturing process of Spanish cured ham. Salt (NaCl) acts as a strong inhibitor of proteolytic activity; sodium nitrate and potassium nitrate do not affect cathepsin D activity; cathepsin L is inhibited at levels of the salts not found in cured ham, and Ca-dependent proteolytic activity is enhanced by nitrate concentrations below 800 ppm. The appearance of phosphate precipitates in several areas of ham has led to the study of phosphate effect on enzymatic activity. Results show that phosphate is an inhibitor of proteolytic activity.

Influence of enrofloxacin administration and alpha-tocopheryl acetate supplemented diets on oxidative stability of broiler tissues.

The objective of this study was to assess the oxidative stability and presence of antibiotic residues in tissues of broilers fed diets supplemented with alpha-tocopheryl acetate and treated with enrofloxacin. The activities of antioxidant enzymes and antibiotic concentrations in chicken breast, leg, and liver were determined. Iron-induced TBA-reactive substances (TBARS) and vitamin E were evaluated in muscles. The antioxidant effectiveness of vitamin E was reflected by TBARS values being lower in antioxidant-supplemented treatments than in the other dietary groups. On the other hand, antioxidant enzyme activities were not substantially affected by dietary treatments. The concentration of enrofloxacin in tissues was considerable, even after withdrawal 12 d before slaughter. Contrary to the findings in previous studies, enrofloxacin was not extensively metabolized to ciprofloxacin. Supplementation of the diet with 100 mg/kg of alpha-tocopheryl acetate did not have a significant effect on the level of antibiotic found in breast muscle samples. When comparing treatments without antibiotic withdrawal time, alpha-tocopheryl acetate supplementation led to a significant decrease in enrofloxacin level in leg and liver samples. These results showed that mutual interactions between different molecules could modify the drug residues in the tissue, which should be taken into account when considering the drug administration and the establishment of a correct withdrawal time.

Effect of pH(24h), curing salts and muscle types on the oxidative stability, free amino acids profile and vitamin B2, B3 and B6 content of dry-cured ham.

The effects of a curing salt composition (with and without nitrifying salts), and the pH at 24h postmortem (pH24>6.0, 5.5

Vitamin (B1, B2, B3 and B6) content and oxidative stability of Gastrocnemius muscle from dry-cured hams elaborated with different nitrifying salt contents and by two ageing times.

The effect of the amount of added nitrate and nitrate plus nitrite to dry-cured hams on the vitamin (B1, B2, B3, B6) content, the antioxidant enzyme superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSHPx) activities and the thiobarbituric acid reactive substances (TBARS) was assessed in Gastrocnemius muscle at the end of two ripening processes. Five different curing mixtures (Hi-N: 600 KNO3; Lo-N: 150 KNO3; Hi-Mix: 600 KNO3+600 NaNO2; Lo-Mix: 150 KNO3+150 NaNO2; Hi-Mix/Asc: 600 KNO3+600 NaNO2+500 sodium ascorbate, expressed as mg of salts added on surface per kg of fresh ham) were evaluated in dry-cured hams aged for 11.5months (standard process, SP) and 22months (long process, LP). Minor differences in target parameters between the hams due to the process were found. The amount of nitrate when it was added alone or as a mixture of nitrate and nitrite, as well as the ascorbate addition to dry-cured hams did not affect vitamin B1, B2 and B3 contents. The level of vitamin B6 was affected by both the amount and the mixture of salts; the addition of nitrite reduced around 40% the content of vitamin B6, but it was not affected by nitrate or ascorbate. The activity of SOD and CAT decreased with the amount of nitrate and nitrite, while GSHPx and TBARS resulted unaffected.

Characterization of Longissimus thoracis, Semitendinosus and Masseter muscles and relationships with technological quality in pigs. 2. Composition of muscles.

The composition of three porcine muscles (Longissimus thoracis: LT, Semitendinosus: ST, Masseter: MS) was characterized and its link with muscle quality was evaluated. The LT muscle had a higher content of tyrosine, tryptophan, and carbohydrates and a lower content of vitamin E and haem iron than the MS muscle, while the ST had similar composition to MS but a lower content of haem iron. Large differences between muscles were observed in relative amounts of most of the major fatty acids. The LT muscle had higher saturated fatty acids (SFA) and n-6:n-3 fatty acid ratio, and lower polyunsaturated fatty acids (PUFA), PUFA:SFA ratio, unsaturation index and average fatty acid chain length than the ST and MS muscles. Muscle pH, redness and chroma were positively correlated with vitamin E and unsaturated lipids and negatively correlated with tyrosine, tryptophan, carbohydrates and saturated lipids, whereas muscle lightness and expressible juice showed similar correlations but an opposite sign with these variables.

Analysis of vitamin B1 in dry-cured sausages by hydrophilic interaction liquid chromatography (HILIC) and diode array detection.

A method based on hydrophilic interaction liquid chromatography (HILIC) and diode array detection (DAD) was developed to quantify thiamine (vitamin B1) concentration in Spanish dry-cured sausages ("chorizo," "fuet," and "salchichón"). Samples were extracted with diluted acid (HCl 0.1M) followed by an enzymatic hydrolysis to release vitamin B1 vitamers from food matrix. Crude extracts were purified on a weak cation exchange SPE cartridge and total thiamine concentration was determined by LC-HILIC-DAD with a limit of detection better than 0.01 mg/100g. The proposed conditions, that do not require the derivatization of the extracts nor the use of fluorescence or MS detectors, are suitable to provide chromatographic separation and identification of vitamin B1 within 8 min. Selectivity, repeatability and accuracy of the method were evaluated with both spiked samples and the reference material Pig Liver BCR® 487. Quantification of vitamin B1 was also carried out for different kinds of commercial samples of Spanish dry-cured products.

The combined effects of alpha-tocopheryl acetate supplementation and enrofloxacin administration on oxidative stability of turkey meat.

1. The combined effects of dietary supplementation of vitamin E and enrofloxacin administration on the oxidative stability of turkey meat were assessed. 2. Enrofloxacin concentrations found in muscles and liver samples from turkeys receiving 200 g/kg of alpha-tocopheryl acetate plus 50 mg/kg of enrofloxacin without a withdrawal period were higher than those of samples administered with 50 mg/kg of enrofloxacin alone. Similarly, meat samples from turkeys receiving 50 mg/kg of enrofloxacin with withdrawal plus 200 mg/kg of alpha-tocopheryl acetate showed a significantly lower vitamin E accumulation than meat samples of the treatment with enrofloxacin without withdrawal plus vitamin E. 3. The results indicated an interaction between the antioxidant and the antibiotic in their effects on oxidation susceptibility and the abiotic safety of meat from turkeys fed on supplemented diets. A mutual stabilisation of both compounds by reducing the effects of free radicals or by affecting the absorption of the compounds is suggested.

Effects of alpha-tocopheryl acetate and beta-carotene dietary supplementation on the antioxidant enzymes, TBARS and sensory attributes of turkey meat.

1. The aim of the study was to evaluate the effects of alpha-tocopheryl acetate (50 mg/kg) and beta-carotene (15 mg/kg) dietary supplementation on the oxidative status of raw turkey breast and leg muscles assessed by thiobarbituric acid test values, the vitamin E levels and the antioxidant enzyme activities. In parallel, a quantitative descriptive sensory analysis was carried out on cooked, stored and reheated samples. 2. Vitamin E was present in sufficient quantity to reduce oxidation, since iron-induced reactive substances (TBARS) were significantly lower in antioxidant-supplemented treatments. The results suggested that the presence of beta-carotene in the diet limits the accumulation of alpha-tocopherol in turkey muscles. 3. In the present study, there was no conclusive relationship between dietary antioxidant supplementation and endogenous antioxidant enzyme activities. 4. Sensory evaluation showed that a longer supplementation time and dose may be necessary in turkeys to prevent meat from rancidity and warmed-over flavour (WOF). Leg pastiness and stringiness were modified by dietary antioxidant supplementation, indicating the possible synergism between antioxidants and cysteine proteinases in the perception of meat quality. 5. Given the modern trends that lead consumers to increase their consumption of poultry meat, it would be interesting to evaluate the commercial potential and cost effectiveness of routine dietary antioxidant supplementation.