Consumers' sensory acceptability of pork from immunocastrated male pigs.

Boar taint is the off-odour or off flavour of cooked pork. Currently, the most common method of controlling boar taint is surgical castration. However, immunocastration has been used in some parts of the world as an alternative to surgical castration. The aim of this study was to evaluate the sensory acceptability of meat from immunocastrated pigs (IM) compared with meat from females (FE), surgically castrated (CM) and entire males (EM). Twenty animals of each type were evaluated by 201 consumers in 20 sessions. Longissimus thoracis muscle of the different animals was cooked in an oven at 180°C for 10min. Consumers scored the odour and the flavour of the meat in a 9-point category scale without an intermediate level. There were no significant differences in consumer's evaluation of meat from IM, CM, and FE. In contrast, EM meat presented a higher percentage of dissatisfied scores and was significantly (P<0.05) less accepted than meat from CM, IM and FE. Consumers' acceptability of EM meat was always lower, independently of its androstenone levels. However meat with low levels of androstenone was more accepted that meat with medium or high levels of this substance. It can be concluded that immunocastration produced pork that was accepted by the consumers, and was indistinguishable from pork from CM or FE.

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.

Detection of sulphamethazine residues in cattle and pig hair by HPLC-DAD.

An HPLC method with diode array detection (DAD) is proposed for the detection of sulphamethazine (SMZ) residues in pig and cattle hair. Hair samples were extracted under alkaline conditions (NH4OH 0.2M for calf samples and NaOH 0.1M for piglet samples) and purified with a dual solid-phase extraction (SPE) cartridge system (reverse phase/strong-cation exchange). Recovery of SMZ in fortified samples varied from 70 to 85%, with a limit of quantification of 0.155 ng/mg. Residues of SMZ (7.2-59.2 ng/mg) were detected both in calf and piglet hairs after a therapeutic treatment with SMZ, while no interfering peak was observed in samples from untreated animals.

Hair analysis for veterinary drug monitoring in livestock production.

This review summarizes the basic information and applications concerning the use of hair analysis for the detection of misuse of therapeutic and anabolic agents in livestock animals. Hair biology, hair-shaft structure and the mechanisms of drug incorporation are described, considering the different factors which can affect the deposition. Sampling and extraction methods are reviewed with special attention to the particularities of this matrix, while the use of different analytical techniques is discussed, taking into account the concentration and the sensitivity required for drug detection. Advantages, drawbacks, promising prospects and possible applications of this technique in the future are also discussed.

Prevalence of boar taint in commercial pigs from Spanish farms.

The presence of boar taint can affect the sensory quality of pork because the "off" odours and flavours can be detected by consumers. The aim of this study was to determine the prevalence of boar taint in pig carcasses from 30 Spanish farms located in different regions of the country. Hot carcass weight and subcutaneous fat thickness means were 79.4±8.19 kg and 18.4±5.09 mm, respectively. Subcutaneous fat samples were classified into different levels according to androstenone and skatole concentrations in adipose tissue measured using GC-MS and HPLC. Androstenone results were: 87.4% of the carcasses below 0.50 µg/g, 7.1% from 0.50 to 1.00 µg/g (medium level), and 5.5% ≥1.00 µg/g (high level). Skatole results were: 88.9% of the carcasses below 0.10 µg/g, 4.5% from 0.10 to 0.20 µg/g (medium level), and 6.6% ≥0.20 µg/g (high level). Given these results, a future online method to classify carcasses according to boar taint is strongly recommended.

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.

Effects of acerola fruit extract on sensory and shelf-life of salted beef patties from grinds differing in fatty acid composition.

The effects of added acerola fruit extract on sensory and shelf-life of beef patties were evaluated. Ground beef was obtained from young bulls fed one of four diets (CON: control, LIN: linseed, CLA: conjugated linoleic acid, LINCLA: LIN plus CLA). Pre-salted (1.8% w/w) beef patties (7.7% fat) with (0.15% w/w) or without acerola were packed in modified atmosphere (80%O2:20%CO2) and displayed in a retail case for 8days. There were no interactions between diet and antioxidant treatments. LIN and/or CLA had no effect on color and lipid stability during display. However, LIN increased n-3 fatty acids in beef and tended to increase intensity of rancid flavor. Addition of acerola extended shelf-life by at least 3 days by improving color and lipid stability and a decreased trend in intensity of rancid flavor of patties without affecting microbial counts. Thus, the use of acerola as a natural antioxidant can be considered an effective method to retard color and lipid oxidation in beef patties.

Procedure for the determination of eight cholesterol oxides in poultry meat using on-column and solvent venting capillary gas chromatography.

A procedure for the determination of eight relevant cholesterol oxides in poultry meat has been developed. The method consists of the enrichment of cholesterol oxides by means of the combined use of solid-phase fractionation and thin-layer chromatography. Florisil and silica columns of 10 g permitted the handling of the total cholesterol oxides content included in the lipid bulk obtained after the Folch's extraction of 20 g of muscle meat. The determination of cholesterol oxides under their trimethylsilyl derivatives was performed by using capillary gas chromatography. The use of a fused-silica open tubular capillary column 30 m x 0.25 mm I.D. coated with 5% phenylmethylsilicone and with a film width of 0.25 micron permitted the separation of all the species. Two modes of injection (on-column and solvent venting) were evaluated and compared for the analysis of cholesterol oxides. On-column capillary gas chromatography (cGC) gave better absolute areas relative standard deviation (R.S.D.) values: 3% to 6% vs. 5% to 7% for solvent venting cGC. Regression analysis for each cholesterol oxide was performed for the two modes of injection. The possibility of large volume injection (10 microliters) by using the solvent venting mode was also evaluated in order to increase the sensitivity of the detection of cholesterol oxides. R.S.D. values for absolute areas ranging from 6% to 14% were obtained. The validation of the method was carried out within the range of 0.1-1 ppm. Absolute and relative recovery values ranging from 80% to 100% were obtained. Statistical analysis revealed that the method was reproducible. cGC-mass spectrometry was also used to confirm the peaks detected by cGC: the total ion chromatogram mode was used for the analysis of samples containing concentrations down to 0.1 ppm of cholesterol oxides. The analysis of fresh and cooked chicken meat revealed the presence of cholesterol oxides proceeding from the autoxidation of the cholesterol B-ring. Finally, saponification was found to be not as accurate as the described procedure for cholesterol oxides analysis.

Procedure for the determination of retinol and alpha-tocopherol in poultry tissues using capillary gas chromatography with solvent venting injection.

A procedure designed for the determination of retinol (vitamin A) and alpha-tocopherol (vitamin E) in poultry tissues has been developed. The procedure involves lipid extraction, saponification, solid-phase clean-up and capillary gas chromatography (cGC). Retinol and alpha-tocopherol were determined separately by cGC-flame ionisation detection using a fused-silica open tubular capillary column, 30 m x 0.25 mm I.D. coated with 5% phenylmethylsilicone and with a film thickness of 0.25 micron. Solvent extraction followed by saponification were sufficient to provide a purified extract which was directly analyzed for retinol by cGC in the solvent venting mode. However, in order to accurately determine alpha-tocopherol by cGC, further purification of the extract by solid-phase extraction was necessary. A silica SPE column was used to remove interfering cholesterol from the extract. alpha-Tocopherol was analyzed in its derivatized form. Absolute and relative recoveries for both vitamins from spiked samples were evaluated. Absolute and relative recoveries ranging from 80 to 95% were obtained for both compounds. 5 alpha-Cholestane and alpha-tocopheryl acetate were used as internal standards. Poultry muscle meat and liver tissue were analyzed for their retinol and alpha-tocopherol content and the peaks detected by cGC were confirmed by cGC-mass spectrometry.

Determination of neutral lipids from subcutaneous fat of cured ham by capillary gas chromatography and liquid chromatography.

The determination of neutral lipids in fat of cured ham is reported. Fat samples were extracted with chloroform-methanol (2:1) and neutral lipids and free fatty acids were separated on an aminopropyl minicolumn, the first fraction with chloroform-2-propanol (neutral lipids) and the second fraction with 2% acetic acid in diethyl ether (free fatty acids). Neutral lipids were fractionated with minicolumns, with aminopropyl and silica stationary phases. Two fractions were obtained with the first column: (A) triglyceride and cholesteryl esters and (B) cholesterol and mono- and diglycerides. Fraction A was applied to the silica column to obtain two new fractions: (C) cholesteryl esters and (D) triglycerides. Fractions B and C were analysed by capillary gas chromatography (cGC) and fraction D by cGC and HPLC. The R.S.D.s obtained were below 5% except for the monoglycerides (8%). Cholesteryl esters were determined by cGC in 5 min with R.S.D. 5%. The main triglycerides identified were PPO, POS, POO, POL and OOO (P = palmitic acid, O = oleic acid, L = linoleic acid; S = stearic). Monoglyceride and diglycerides having 18, 34 and 36 carbon atoms were the most abundant. The determination of triglycerides by HPLC was more difficult than by cGC because the linearity with HPLC was concentration dependent. The procedure allowed the determination of neutral lipid classes without derivatization of mono- and diglycerides.

Rapid determination of skatole and indole in pig back fat by normal-phase liquid chromatography.

A rapid normal-phase high-performance liquid chromatographic method for the quantitative determination of indole and skatole in pig back fat samples has been developed. The compounds were extracted by shaking the samples at ambient temperature in hexane-2-propanol (92:8, v/v). The sample preparation procedure was simple because it was not necessary to remove the fat from the samples. The compounds were separated on a 250 x 4.6 mm I.D., 5 micron Hypersil aminopropylsilica column. Fluorescence (excitation at 280 nm and emission at 360 nm) was used for selective detection. Recoveries for skatole and indole, relative to the internal standard, were 10.3 +/- 0.9% and 99.6 +/- 4.4%, respectively. Linearity determined in fat samples was in the range of 0.05-1 microgram/g and the correlations observed were R2 = 0.9914 for the indole and R2 = 0.9916 for skatole.

Evaluation of an extraction method in the determination of the 2,4,6-trichloroanisole content of tainted cork.

A method based on solvent extraction and GC-electron-capture detection analysis for the determination of 2,4,6-trichloroanisole (TCA) from cork has been evaluated and optimised. Our sample treatment consists of an extraction stage with pentane while the sample and solvent are kept in contact in a mechanical shaker (shake-flask extraction). Different extraction conditions have been tested in order to find the best compromise between efficiency and time of analysis. Different columns were evaluated for use in the concentration and purification step. A silica column was found to give the best performance in terms of recovery of TCA and repeatability. Pentane and mixtures of pentane-diethyl ether at different ratios were tested as eluting agents. It was found that 10 ml pentane allowed the recovery of retained TCA. Finally, the eluate was concentrated and injected into the chromatograph for TCA determination. The optimised chromatographic conditions enabled the quantification of TCA and 2,6-dichloroanisole, which was assayed as the internal standard. The shake-flask extraction method was compared with Soxhlet and ultrasound assisted extraction procedures using pentane as a solvent. Similar results were obtained for the shake-flask and Soxhlet extraction methods, while sonication gave significantly lower recoveries. The optimised shake-flask method was applied to determine the distribution of TCA in naturally contaminated cork bark.

Role of 4-phenyl-3-buten-2-one in boar taint: identification of new compounds related to sensorial descriptors in pig fat.

The possible contribution of other compounds to the development of boar taint in fat samples with low concentrations of skatole and androstenone and classified as tainted was evaluated by GC-MS in the SCAN mode. Skatole and androstenone were determined by normal phase HPLC and GC-MS, respectively. For the identification of other compounds fat samples were purified with a gel filtration column and the second fraction was saponified at room temperature with KOH/3 N MeOH. 4-Phenyl-3-buten-2-one was the main compound identified in the fat samples, and its identification was corroborated by comparison with a standard solution obtained from a commercial source and by HPLC. The sensorial analysis of 4-phenyl-3-buten-2-one showed its possible contribution to boar taint. The possible contribution of phenol derivatives and short-chain fatty acids was also evaluated.

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.

Cholesterol oxidation in meat from chickens fed alpha-tocopherol- and beta-carotene-supplemented diets with different unsaturation grades.

The production of B-ring and side-chain oxysterols was evaluated in meat from chickens fed diets differing by the kind of oil or fat added. The effect of supplementary levels of natural antioxidants, as alpha-tocopherol and beta-carotene, on the meat cholesterol oxidative stability was also studied. Lard, sunflower and olive oil were used as dietary fat. Raw and cooked meats were analyzed for oxysterols, and cholesterol was also quantified. Oxysterol analyses were carried out by combining the use of solid-phase extraction, thin-layer chromatography, capillary gas chromatography, and capillary gas chromatography-mass spectrometry. Oxysterols were detected within the 0.1-0.5 microg/g range in raw meat. Cooking increased the oxysterol content of the meat, and levels as high as 5 microg/g muscle tissue were observed. B-Ring oxysterols were mainly produced: the alpha- and the beta-epoxycholesterols, the 7alpha- and 7beta-hydroxycholesterols, and the 7-ketocholesterol. The results showed that the meat from the chickens fed the olive oil-based diet containing alpha-tocopherol at 200 mg/kg of diet presented the best cholesterol oxidative stability. A positive effect could not be found for dietary beta-carotene administered at levels of 15 and 50 mg/kg of diet. Furthermore, a significant decrease in the tissue cholesterol content was observed with the olive and the sunflower oil-based diets.

Evaluation of the contribution of skatole, indole, androstenone and androstenols to boar-taint in back fat of pigs by HPLC and capillary gas chromatography (CGC).

Fifteen samples of fat with boar taint were selected by means of a trained panel-test, from 200 carcasses of entire male pigs, and they were analyzed to determine skatole, indole, 5α-Androst-16-en-3-one (5α-An), 5α-Androst-16-en-3α-ol (5αAn3α) and 5α-Androst-16-en-3ß-ol (5αAn3ß). The extraction was carried out with methanol, the extract was placed at -20°C during 10 min to eliminate the fat and after evaporation of methanol a Florisil clean up was applied to obtain skatole and indole in a separate fraction from 5αAn and androstenols. Skatole and indole were determined by HPLC in normal phase with a Spherisorb-NH(2) column and 5αAn and androstenols were analyzed by capillary gas chromatography (CGC). Selective procedures were used for detection: ratio at 220 nm and 280 nm (skatole/indole) and CGC coupled to a mass spectrometer working in the SIM (selected ion monitoring) mode at m/z 272 (o5αAn) and m/z 274 (androstenols). The results obtained showed that skatole and 5αAn concentrations exceeded that typical thresholds values in more than 50% of samples analyzed, suggesting a similar influence on boar taint. 5αAn3ß showed higher concentrations than 5αAn3α, but lower than 5αAn, exceeding only 1·00 µg/g in three samples.

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.

Skatole and indole concentrations in Longissimus dorsi and fat samples of pigs.

A HPLC-NP (normal phase-high performance liquid chromatography) method for determining the concentration of skatole and indole in Longissimus dorsi samples is described. Lipids containing skatole and indole were extracted in chloroform:methanol (2:1) at room temperature and dehydrated by liquid-liquid extraction with an aqueous solution saturated with 10% of sodium chloride. The organic phase was evaporated to dryness and redissolved in 10 ml of hexane:2-propanol (92:8). Indolic compounds were separated on a Hypersil aminopropylsilica column (5 µm) (250×4.6 mm i.d.). The mobile phase was hexane:2-propanol (92:8) and detection was by fluorescence (excitation at 280 nm and emission at 360 nm). Linearity was found in the range of 0.05-0.4 µg/g and the coefficient of correlation was above 0.99 for both compounds. The within day (n=5) variation was at 0.05, 0.2 and 0.4 µg/g and the CV (coefficient of variation) values for relative areas determined at these concentrations were less than 13%. This method was used to compare the concentrations of skatole and indole in different samples: L. dorsi muscle, the fat covering the L. dorsi and subcutaneous fat. A correlation was observed between the concentration of indole and skatole in the back fat and fat covering the L. dorsi samples (P<0.001, r=0.99). No significant correlation was obtained in L. dorsi samples, between skatole and indole levels. In spite of the correlation shown between skatole and indole concentrations in the back fat and L. dorsi samples, the mean concentrations of these compounds were significantly higher (P<0.05) in the back fat samples.

Lipolysis and lipid oxidation during chilled storage of meat from Large White and Pietrain pigs.

The day after slaughter, six chops of Longissimus lumborum from each of 10 Large White pigs and six Piétrain pigs were packed individually under vacuum and kept at 3-4 °C in the dark. At 1, 5 and 9 days after slaughter, two chops were used for analysis of lipids, thiobarbituric acid reactive substances (TBARS), sarcoplasmic Ca(2+) and sarcoplasm and mitochondria phospholipase A(2) activity. Free fatty acid content was higher in Piétrains than in Large Whites and increased with keeping time. Total lipids of Large White pigs contained more saturated fatty acid (SFA) and monounsaturated fatty acid (MUFA) and less polyunsaturated fatty acid (PUFA). Large Whites had less dioleoyl-linoleyl-glycerol (OOL) and Palmitoyl-oleoyl-linoleyl-glycerol (POL) and more Palmitoyl-oleoyl-stearyl-glycerol (POS) than Piétrains. The percentages of SFA and MUFA decreased and the percentage of PUFA increased with time in FFA of Large White pigs. In Piétrains, similar changes were observed between days 1 and 5, but later the percentages of SFA increased and the percentage of PUFA decreased again. TBARS tended to increase with time particularly in Piétrains. Sarcoplasmic phospholipase A(2) decreased between days 5 and 9 in both breeds. Sarcoplasmic calcium was markedly higher at day 1 in Piétrains than in Large Whites then the difference decreased. These breed differences in lipid composition differences and lipid changes during storage are considered too small to be of practical importance, for instance in influencing the choice of a breed for pork production.

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. ©