Pork Muscle Research Articles

The influence of pork quality traits and muscle fiber characteristics on the eating quality of pork from various breeds

The purpose of this study was to compare parameters associated with pork quality, muscle fiber, and eating quality among various breeds, and to examine if differences in eating quality were associated to pork quality and muscle fiber characteristics. For carcass and pork quality, although there were significant differences among breeds, the values of parameters in all pigs were assigned a normal quality class, a likely outcome of the similarity in the area percentage of type I and IIB fibers. For eating quality, pork loins from Berkshire pigs were more tender and full of pork flavor than Landrace and Yorkshire pigs. Except juiciness and mouth coating, over 20% of the variability in the eating quality parameters can be explained by pork quality traits and muscle fiber characteristics using multiple regression analysis. Furthermore, differences in muscle pH 24 h , cooking loss, shear force, and NPPC marbling score could explain a large proportion of variation in eating quality parameters associated with the texture of pork.

Monitoring NIRS calibrations for use in routine meat analysis as part of Iberian pig-breeding programs

The meat industry, animal breeding programmes and consumer expectations regarding meat-product labelling require fast screening techniques for the determination of meat quality. The potential of Near Infrared Spectroscopy (NIRS) for this purpose has been clearly demonstrated. This paper reports on the development, validation and updating of NIRS models for the routine analysis of ground Iberian pork muscles (gluteus medius, masseter, longissimus dorsi and spinalis dorsi). Modified Partial Least Squared (MPLS) calibration models were obtained to predict fat, moisture and protein content. The method employed was based on the use of different Mahalanobis distances for the recalibration of models, enabling the number of recalibration samples to be reduced. The final recalibrated models displayed a Standard Error of Cross-Validation (SECV) of 0.35% and a Determination Coefficient of Cross-Validation (RCV2) of 0.99 for fat; values for moisture were SECV=0.46% and RCV2=0.97; while for protein were SECV=0.52% and RCV2=0.90, indicating good spectral matching even for muscle types not included in the calibration.

Mild Protein Oxidation Enhanced Hydration and Myofibril Swelling Capacity of Fresh Ground Pork Muscle Packaged in High Oxygen Atmosphere

This study investigated the influence of an oxygen-enriched modified atmosphere packaging (HiOx: 80% O₂/20% CO₂) in comparison with air-permeable polyvinylchloride (PVC) wrapping and partial vacuum (VP: 60%) packaging on the ability of myofibrils to imbibe water during retail display of fresh ground pork at 2 to 4 °C. Both HiOx and PVC muscles after 4 d showed maximum myofibril swelling and A-band dissolution when isolated myofibrils were subjected to a graded series of salt solutions (0.2→0.4 M NaCl with 10-mM sodium pyrophosphate, pH 6.2), while VP samples exhibited no remarkable change. Protein carbonyl content increased substantially from day 0 to 4 in all muscle samples. For HiOx, muscle hydration capacity increased linearly (P < 0.05) during storage up to 14 d, corresponding to protein carbonyl production. No significant changes in hydration properties were noted in VP muscle samples, which also maintained lower levels of protein oxidation, during storage up to 21 d. These results indicated that packaging in modified atmosphere with high levels of oxygen could result in increased protein oxidation but enhanced hydration capacity of fresh meat. Packaging of fresh meat, including ground pork, under an oxygen-enriched atmosphere condition is widely used in the industry to preserve red color of meat. Results from the present study indicate that high oxygen packaging has a discordant effect on fresh ground pork: it enhances hydration but decreases water-binding, and this seems to be caused by increased swelling of muscle fibers due to mild protein oxidation. Hence, it is advisable to employ a water-binding agent in this type of packaging system so as to retain the moisture in stored fresh pork products while maintaining the color stability.

Multi-residue method for the confirmation of four avermectin residues in food products of animal origin by ultra-performance liquid chromatography–tandem mass spectrometry

A confirmatory method was developed for the rapid determination of abamectin, ivermectin, doramectin and eprinomectin residues in various food products of animal origin, such as pork muscle, pork liver, fish and milk. Samples were homogenized, extracted and de-proteinized by acetonitrile, cleaned via two-step cleaning procedure using Bond Elut C18 SPE columns and then alumina-N cartridges. All the four avermectin residues in different animal-food products were simultaneously separated and determined by ultra-performance liquid chromatography–electrospray ionization tandem mass spectrometry (UPLC–ESI–MS/MS) within 3.5 min. Data acquisition under positive ESI–MS/MS was performed by applying multiple reaction monitoring (MRM) for both identification and quantification, and mass spectrometric conditions were optimized to increase selectivity and sensitivity. The matrix-matched calibration curves for different matrices, such as pork muscle, pork liver, fish and milk, were constructed and the interference effect of different sample matrices on the ionization was effectively eliminated. The UPLC–MS/MS method was validated with satisfactory linearity, recovery, precision and stability. Matrix-matched calibration curves of abamectin, ivermectin, doramectin and eprinomectin in four different matrices were linear (r2 ≥ 0.990, goodness-of-fit coefficients ≤12.8%) in the range 2.5–200 µg kg−1. The limits of detection and quantification for the four avermectins were in the range 0.05–0.68 and 0.17–2.27 µg kg−1, respectively. Recoveries were 62.4–104.5% with good intra- and inter-day precision. The method was rapid, sensitive and reliable, and can be applied to the quantitative analysis of avermectin residues in different animal-food products.

Long Chain Omega-3 Fatty Acid Levels in Loin Muscle from Transgenic (fat-1 gene) Pigs and Effects on Lipid Oxidation During Storage

Studies suggest a diet rich in long chain omega-3 fatty acids (LCn3) can promote visual, neural and vascular health. Pork muscle typically has small amounts of LCn3. A transgenic technology involving the fat-1 gene has been developed to increase LCn3 in various pig tissues; however, pork loin muscle has not been examined to date. We have determined that the LCn3 content in loin muscle (Longissimus) from fat-1 pigs was 1.59–2.24 g/100 g lipid compared to 0.34–0.38 g/100 g lipid in control samples. Lipid oxidation products were measured in ground and salted loin muscle from control and fat-1 pigs during storage at −4°C. There was no clear trend as to whether the fat-1 gene technology increased or decreased oxidative stability of the muscle during storage based on lipid peroxide and thiobarbituric acid reactive substances (TBARS) values. There were a greater number of volatiles detected in stored loin from fat-1 pigs compared to control. Volatiles common to control and fat-1 pigs were elevated in stored loin from fat-1 pigs. This is the first report indicating that the use of fat-1 transgenic technology significantly increases the amount of desirable LCn3 in pork loin muscle.

Validation of multi-residue method for determination of pesticides in meat products using official guideline of analytical methods in Japan

A multi-residue analytical method for 185 pesticides (including metabolites) in meat products was validated by the guideline of the Japanese Ministry of Health, Labour and Welfare. This method involved extraction with ethyl acetate–cyclohexane (1 : 1) and cleanup by gel permeation chromatography (GPC), and primary secondary amine (PSA) and silica-gel mini-column solid-phase extraction (SPE). The target compounds were determined by gas chromatography/mass spectrometry (GC-MS) and liquid chromatography/mass spectrometry (LC-MS). Validation tests were performed on beef, chicken and pork muscles fortified at 0.01 and 0.10 μg/g. Among 185 pesticides tested, 175 in beef, 175 in chicken and 172 in pork were found to conform to the guideline when the solvent standard was used, and 181 in beef, 176 in chicken and 177 in pork when the matrix-matched standard was used. Although significant matrix effects were not observed for most pesticides, use of the matrix-matched standard was preferable for accurate quantitation to the solvent standard. Limits of quantitation (S/N ≥10) were set at 0.01 μg/g for all pesticides. The method was applied to the regulatory monitoring of meat products.

Application of acetylacetone chelation solid-phase extraction to GFAAS measurements of trace amounts of beryllium in livers and muscles of poultry and livestock

Trace amounts (0.004–0.55ng) of beryllium (Be) in a dried bovine liver sample (20mg) can be accurately determined by graphite-furnace atomic absorption spectrophotometry (GFAAS) after treating with microwave digestion (HNO3/H2O2) at 85°C for 10min and using acetylacetone as a chelating agent in the presence of an acetate buffer (pH 6.0). The method detection limit (MDL, 3σ) for Be was found to be 0.18ngg−1 and the limit of quantification (LOQ, 10σ) was found to be 0.60ngg−1; the calibration graph was linear up to 27ngg−1. The Be contents measured in four liver and four muscle samples (BCR CRM-185R bovine liver, BCR CRM-384 pork muscle, and six samples collected in Kaohsiung, Taiwan, ROC) were between 2.3 and 4.7ngg−1. Good spiked recoveries (96.0–103.0%) were obtained for these eight samples with a relative standard deviation (RSD, n=3) ⩽3.0%. The method could be applied to measurements of Be in livers and muscles of poultry and livestock.

Influence of heat on protein degradation, ultrastructure and eating quality indicators of pork

Heating temperature is an important factor affecting meat palatability. This study aimed to evaluate the influence of heating temperature on some eating quality indicators, protein degradation and ultrastructure of pork muscle fibres and their correlations. Cooking loss (CL) increased gradually (P < 0.05) with increasing temperature. Warner-Bratzler shear force (WBSF) increased in two separate phases from 25 to 50 °C and again from 60 to 100 °C (P < 0.05), with a steady phase from 50 to 60 °C (P > 0.05); conversely, a significant increase in pH (P < 0.05) occurred between 50 and 60 °C. Strong correlations (P < 0.01) among pH, CL, WBSF and colour parameters L* and b* were observed following the heating process. Increasing temperature induced gradual degradation of many muscle proteins, but myosin was not significantly degraded until 80 °C and actin showed no visible degradation throughout the whole heating process. Meanwhile, the structure of muscle fibres also changed significantly on heating, with sarcomeres contracting transversely and longitudinally and becoming condensed, but there was no occurrence of breakage within fibres. Heating temperature has a great effect on eating quality indicators, protein degradation and ultrastructure of pork muscle fibres. .

Electrical conductivity of particle–fluid mixtures in ohmic heating: Measurement and simulation

The electrical conductivity (EC) of food systems is a key parameter of the ohmic heating process. Ohmic heating experiments were conducted using a Teflon cylindrical cell. Electrical conductivity values were evaluated for the ohmic processing (25–125 °C) of blanched, 2-cm cubic particles (carrot, potato, radish, beef muscle, pork muscle and commercial ham) dispersed in carrier fluid (5% w/w starch–water solution with 0.15–1.5% w/w salt concentrations). Assuming an analogy between thermal conductivity (TC) and EC five existing TC theoretical models (series, parallel, two forms of Maxwell–Eucken models and effective medium theory) were applied and evaluated for EC of various solid–fluid structural systems. Parallel and Series models are not practically applicable in real food system, however they can indicate the useful limit values of highest and lowest EC among all two-phase structures. The first Maxwell–Eucken model, which describes solid particles dispersed in continuous liquid, showed the best agreement between predicted EC values and experimental data. This model provided a useful and relatively simple new approach to predict the effective EC for mixtures of different types of solid food particles immersed in liquid food.

Determination of 23 β2-agonists and 5 β-blockers in animal muscle by high performance liquid chromatography-linear ion trap mass spectrometry

A high performance liquid chromatography-linear ion trap mass spectrometry method using isotope dilution technique has been developed for the simultaneous determination of 23 β2-agonists and 5 β-blockers in animal muscle tissues. Pork and chicken muscle samples were acid hydrolyzed and extracted with 5% trichloracetic acid in water, and then cleaned up using MCX solid phase extraction (SPE) cartridge. Methanol and 0.1% formic acid were used as mobile phases for gradient elution. A Waters Atlantis®T3 column was used for separation. ESI positive ion scan mode was used with selective reaction monitoring. 9 β2-Agonists labeled by the deuterium isotope were used as internal standards for quantification. The linear ranges of 23 β2-agonists and 5 β-blockers were 5–200 μg/L, the coefficient of correlation was not less than 0.995, and the limit of detection for each compound in the muscle tissue was below 0.2 μg/kg. The recoveries of each compound in the spiked samples at three levels 5, 10, 20 μg/kg were in the range of 47.3%–123.7%, and the relative standard deviations were in the range of 3.2%–25.7%. The developed method is sensitive and specific for the determination of β2-agonists and β-blockers in pork and chicken muscle samples.

EFFECTS OF ON‐FARM MAGNESIUM SUPPLEMENTATION THROUGH WATER ON PORK QUALITY UNDER TWO SLAUGHTER CONDITIONS

ABSTRACT The objective of this study was to determine the effects of pre‐harvest Mg supplementation and stunning method on longissimus (LM) and semitendinosus (SM) pork muscle quality. Magnesium was supplemented for 2 days in drinking water (300 ppm) before pigs were harvested at a commercial packing plant using either electrical or CO2 stunning. Magnesium supplementation did not affect (P &gt; 0.10) ultimate pH, initial fluid loss, retail display purge loss or color of the LM and SM. Pork quality was generally improved in LM and SM samples obtained from the plant using CO2 stunning as evidenced by reduced initial fluid loss (P &lt; 0.001), reduced purge loss (P &lt; 0.05) and lower L* (darker), a* (less red) and b* (less yellow) values (P &lt; 0.05) during an 8‐day retail display. Pork quality was improved when using CO2 stunning technology; however, Mg supplementation did not improve pork quality in either plant.PRACTICAL APPLICATIONSPork quality is one of the main issues for the pork industry to consider in order to remain competitive in a global market. We evaluated the supplementation of Mg through the water in collaboration with a swine production company and two large commercial packing plants. Clear differences in pork quality were evident, with the packing plant using CO2 stunning having superior pork quality compared with the plant using electrical stunning. Supplementation of Mg through water can be applied on the farm immediately at a very low cost, but was not effective in improving pork quality in two commercial packing plants under practical conditions.

Characterization of Peptides Released by in Vitro Digestion of Pork Meat

The main objective of this work was to identify and characterize the peptides generated by simulated gastrointestinal digestion of pork meat (longissimus dorsi) by the sequential action of pepsin and pancreatin. The obtained hydrolysate was analyzed by liquid chromatography coupled to a quadrupole time-of-flight mass spectrometer equipped with a nanoelectrospray ionization source (nano LC-ESI-MS/MS). Using this technique 51 different peptides were identified in the hydrolysate, corresponding to fragments of the main structural muscle proteins and some well-known sarcoplasmic proteins. To the best of our knowledge, this constitutes the highest number of peptides identified in pork meat digests. Peptide fragment size ranged from six to sixteen amino acids, being rich in proline residues and thus making them more resistant to further degradation by digestive enzymes. The present study constitutes a clear evidence of the extensive degradation that pork muscle proteins would undergo after gastrointestinal digestion, giving rise to a wide variety of short peptides. So, the use of in vitro digestion contributes to a better knowledge about the generation of peptides from diets with high protein quality.

Enantioselective determination of cypermethrin in pig muscle tissue by immunoaffinity extraction and high performance liquid chromatography

SummaryA high performance liquid chromatography method was developed to detect enantiomers of cypermethrin in pork muscle. Eight isomers of racemic cypermethrin were separated using a normal mobile phase of hexane–isopropyl alcohol (99.3–0.7, v/v) on a chiral CD‐ph column in 25 min. The elution order of isomers was ascertained using enantiomer/diastereomer enriched cypermethrin standards. The extracts from pork samples were cleaned up by immunoaffinity column before detection. The recoveries from samples fortified levels of 0.1 and 1 mg kg−1 ranged from 67.3% to 113.5% with a relative standard deviation 6.7–16.8%; sufficient to effectively measure cypermethrin enantiomer concentrations in pig muscle tissue samples in the future.

Improved compatibility of liquid chromatography with electrospray tandem mass spectrometry for tracing occurrence of barbital homologous residues in animal tissues

This work describes a liquid chromatography–tandem mass spectrometry (LC–MS/MS) procedure for multiplex screening, ultratrace quantification and reliable confirmation of barbital series residues in animal-derived food matrices. The method is developed based on a distinct dependency of the electrospray ionization (ESI) response of nine structural homologues on LC eluent properties and gas-phase ion chemistry during the ESI process. The “wrong-way-round” negative ionization aspect has been explored to optimize the compatibility of the hyphenated LC–MS/MS technique, which facilitates detection limits at 30–100-fold lower than 0.01 ppm without derivatization or post-column basification step. A mobile phase using methanol modified with 0.01% acetic acid is adopted to achieve an approximately 2–9-fold increase in signal-to-noise ratio over the results under suboptimal conditions. There is no significant differential matrix effects or deuterium isotope effects on chromatographic retention and ESI responsiveness at all levels across the different analyte–matrix pairs. Mean recoveries ranged from 79.6% (barbital) to 108% (secobarbital) at fortified levels of 0.5–20 ng/g within relative standard deviations less than 11%. Between-run repeatability and within-laboratory reproducibility were 3–11% and 5–13%, respectively. An ion ratio criterion for valid detection limit data for simultaneous screening of homologous multiresidues in complex sample matrices is proposed. The satisfactory applicability of the newly described procedure to 43 real samples including pork, poultry meat, swine liver, fish tissue and shrimp muscle demonstrated the LC–MS/MS technique with facile sample handling can serve as an attractive alternative analytical method accepted for regulatory purpose.

Evaluation of Technological Quality of Meat Produced from Nsukka Local Abattior

The technological quality of raw meat from Nsukka local abattoir was evaluated by analyzing the proximate composition, water holding capacity, pH, Napole yield and sensory colour and texture of longissimus dorsi [LD] and psoas major [PM] of beef and pork. Results show that moisture [71.36 – 72.76%], protein [21.37 – 22.75%], fat[3.81 – 4.36%] and ash [0.80 – 1.30%] contents were within the range known for fresh raw beef and pork. Due to species differences and effect of scalding, pork had significantly lower ultimate pH [5.35 – 5.54] compared to beef [5.83 –5.91]; with 70% of the pork muscles being in the PSE range contrasted with 38% of those of beef. Also due to muscledifferences LD had lower ultimate pH compared to PM, although the differences were not found to be significant [p

Evaluation of Technological Quality of Meat Produced from Nsukka Local Abattior

The technological quality of raw meat from Nsukka local abattoir was evaluated by analyzing the proximate composition, water holding capacity, pH, Napole yield and sensory colour and texture of longissimus dorsi [LD] and psoas major [PM] of beef and pork. Results show that moisture [71.36 – 72.76%], protein [21.37 – 22.75%], fat [3.81 – 4.36%] and ash [0.80 – 1.30%] contents were within the range known for fresh raw beef and pork. Due to species differences and effect of scalding, pork had significantly lower ultimate pH [5.35 – 5.54] compared to beef [5.83 – 5.91]; with 70% of the pork muscles being in the PSE range contrasted with 38% of those of beef. Also due to muscle differences LD had lower ultimate pH compared to PM, although the differences were not found to be significant [p had higher cooking loss. Napole yield was higher for beef and LD compared respectively to pork and PM. Hardness data showed that pork and PM were harder than beef and LD respectively but the toughness data showed LD to be tougher than PM. Sensory texture [finger feel] data correlated with hardness score [r= -0.73] showing that hardness instead of toughness influenced texture preference. Hardness and toughness as well as sensory texture had high coefficient of variation.

Quality Evaluation of an Ohmically Cooked Ham Product

Selected parameters (cooking loss, instrumental colour and texture and sensory quality) of a brine-injected pork muscle cooked by a novel and rapid ohmic cooking protocol were examined and compared with those obtained in conventionally cooked samples. Ohmic samples were cooked using either a low-temperature long-time (LTLT) protocol (2 min equilibration, 5 min ohmic heating to 70 °C, 8 min holding) or a high-temperature short-time (HTST) procedure (2 min equilibration, 6 min ohmic heating to 95 °C) performed within a hot air cabinet set at 80 °C (LTLT) and 100 °C (HTST). Conventional cooking (steam oven at 80 °C for 120 min) was conducted to a core temperature of 70 °C. The LTLT treatment gave a much lower cooking loss value (4–5% lower, p < 0.05) than the other treatments, though the full magnitude of this difference was not completely reflected in the proximate composition of the cooked products. Ohmically cooked ham showed a significantly (p < 0.05) lighter surface colour with Hunter L values of 65.3 (LTLT) and 63.5 (HTST) relative to the control (61.4). Texture profile analysis (TPA) indicated a significant difference (p < 0.05) in hardness (N) especially between the HTST surface (82.1 N) and the conventional centre (58.8 N). Although the ohmic cooking protocols yielded products with quite acceptable eating qualities, sensory evaluation found the overall quality of the conventionally cooked ham to be significantly (p < 0.05) superior, indicating that further optimisation of the ohmic cooking protocols would be required prior to any commercial adoption.

A $K$-Band Planar Active Integrated Bi-Directional Switching Heat Applicator With Uniform Heating Profile

A planar bi-directional microwave heat applicator integrated with active circuits on a single platform is presented in this paper. <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</i> -band frequencies have been utilized to facilitate low-power hyperthermia and high-level integration. The active source module implemented with GaAs-based multichip monolithic microwave integrated circuits delivers 1.4 W at 20 GHz into the co-integrated planar applicator, which has three planar coaxial apertures on each side for wide-area bi-directional hyperthermia. The heating volume is further enhanced by employing switched heating, which effectively doubles the hyperthermic volume. The bio-heat equation is solved to find the optimum switching time, as well as to achieve uniform heating across the apertures. The effectiveness of the proposed applicator has been demonstrated by <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in-vitro</i> heating experiments on the pork muscle, which showed 210.6- mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> heating volume using only 1.4 W of on-board source power. The entire applicator was realized in a small form factor (5 mm times 50 mm times 0.524 mm) for minimally invasive interstitial insertion. The cost of the hyperthermia system can be drastically reduced by integrating active components on the applicator platform.

Qualitative-feed-restricted heavy swine: meat quality and morpho-histochemical characteristics of muscle fibers

To evaluate the effect of different levels of qualitative feed restriction (0, 5, 10, 15 and 20%) on pork quality and muscle morpho-histochemical characteristics, 60 castrated male swines were used. Ten animals were slaughtered at 89 kg BW. Other 50 pigs were fed experimental diets and slaughtered at 128 kg BW. Qualitative restriction increased pH45, and water holding capacity, and reduced the redness, yellowness and cholesterol concentrations of Longissimus lumborum. Quadratic tendency for oleic acid contents of loin and fiber cross-section area of Multifidus dorsi (P=0.08) were observed, with maximum point at 11-12% of restriction. No effect (P&gt;0.1) on percentage of M. dorsi fibers SO, FG and FOG was found. The meat from 128-kg-BW pig showed numerically higher values for colorness, water losses, and lipid content and lower shear force than 89-kg-BW pigs. Qualitative feed restriction for finishing swines neither affected negatively pork quality nor modified the muscle fiber profile.

Determination of Pyrethroid Residues in Pork Muscle by Immunoaffinity Cleanup and GC-ECD

A method was developed to determine six pyrethroids (tau-fluvalinate, fenpropathrin, λ-cyhalothrin, cyfluthrin, α-cypermethrin and deltamethrin) in pork muscle by immunoaffinity column cleanup and gas chromatography-electron capture detection. Spiked pork muscle samples at 5, 20, 50 μg kg−1 were extracted with petroleum spirit-diethyl ether (1:1, v/v). Fat was eliminated by liquid–liquid partition between acetonitrile and petroleum spirit. An immunoaffinity column (IAC) was used for further cleanup. The IAC column was prepared by coupling the polyclonal antibodies to the protein A sepharose gel and the resulting affinity gel columns were sufficiently stable for multiple reuse. Target compounds were adsorbed at pH 7.4 and after extensive washing, eluted with 3 mL methanol. Recoveries of the six pyrethroids were typically >70%. The detection limit was 2 μg kg−1 for λ-cyhalothrin and α-cypermethrin and 5 μg kg−1 for cyfluthrin, deltamethrin, fenpropathrin and tau-fluvalinate. Repeat analyses of pork muscle samples showed good repeatability. The method was applied to detect residues in meat samples.