Pork Muscle Research Articles

Measurement of Young’s Modulus and Internal Damping of Pork Muscle in Dynamic Mode

Automotive shocks involve various tiers’ speed for different human body tissues. Knowing the behavior of these tissues, including muscles, in different vibration frequency is therefore necessary. The muscle has viscoelatic properties. Dynamically, this material has variable mechanical properties depending on the vibration frequency. A novel technique is being employed to examine the variation of the mechanical impedance of pork muscle as a function of frequency. A force is imposed on the lower surface of the sample and acceleration is measured on its upper surface. These two parameters are measured using sensors. The sample is modeled by Kelvin–Voigt model. These measures allow deducing the change in the mechanical impedance modulus (/[Formula: see text]/ [Formula: see text] /Force: Acceleration/) of pork muscle as a function of vibration frequency. The measured impedance has a resonance of approximately 60[Formula: see text]Hz. Best-fit parameters of theoretical impedance can be deduced by superposition with the experiment result. The variation of Young’s modulus and internal damping of pig’s muscle as a function of frequency are determined. The results obtained between 5[Formula: see text]Hz and 30[Formula: see text]Hz are the same as determined by Aimedieu and al in 2003, therefore validating our technique. The Young’s modulus of muscle increases with the frequency, on the other hand, we note a rating decrease of internal damping.

Direct tissue sampling of diazepam and amitriptyline using mixed-mode SPME fibers: A feasibility study

Here, we report on the applicability of the C18/SCX fiber (containing both C18 and strong cation exchange groups) as a direct sampling tool in tissue. An agarose gel model was used as semi-solid tissue surrogate, to mimic changes in matrix tortuosity as expected in tissue. Pork muscle was used as tissue source and was loaded with diazepam or amitriptyline using 24h incubation in spiked phosphate-buffered saline (PBS). Diazepam is neutral and its behavior is predictable based on the octanol–water partition coefficient (Kow). Amitriptyline is >99% positively charged at pH 7.4, and is likely to behave differently in both agarose gel and tissue compared to neutral compounds. The proposed SPME method yielded detectable fiber concentrations after direct sampling in agarose gel and loaded tissue, including short sampling times and different loading concentrations in tissue. Sorption affinity of both diazepam and amitriptyline is decreased when sampling from agarose gel compared to PBS, due to the presence of different binding groups in agarose. Sorption affinities from tissue are even further decreased compared to agarose gel. This indicates that tissue contains even more binding sites for these compounds compared to agarose gel. Interestingly, for both compounds, equilibration in tissue occurred faster than equilibration in agarose gel or PBS, most likely caused by direct fiber contact or through facilitated transport. Although more research is needed to obtain good quantitative results, these results show that the C18/SCX fiber is a sensitive tool to determine tissue concentrations of neutral and cationic compounds.

Sensitivity of tissue properties derived from MRgFUS temperature data to input errors and data inclusion criteria: ex vivo study in porcine muscle

This study evaluates the sensitivity of two magnetic resonance-guided focused ultrasound (MRgFUS) thermal property estimation methods to errors in required inputs and different data inclusion criteria. Using ex vivo pork muscle MRgFUS data, sensitivities to required inputs are determined by introducing errors to ultrasound beam locations (rerror = −2 to 2 mm) and time vectors (terror = −2.2 to 2.2 s). In addition, the sensitivity to user-defined data inclusion criteria is evaluated by choosing different spatial (rfit = 1–10 mm) and temporal (tfit = 8.8–61.6 s) regions for fitting. Beam location errors resulted in up to 50% change in property estimates with local minima occurring at rerror = 0 and estimate errors less than 10% when rerror < 0.5 mm. Errors in the time vector led to property estimate errors up to 40% and without local minimum, indicating the need to trigger ultrasound sonications with the MR image acquisition. Regarding the selection of data inclusion criteria, property estimates reached stable values (less than 5% change) when rfit > 2.5 × FWHM, and were most accurate with the least variability for longer tfit. Guidelines provided by this study highlight the importance of identifying required inputs and choosing appropriate data inclusion criteria for robust and accurate thermal property estimation. Applying these guidelines will prevent the introduction of biases and avoidable errors when utilizing these property estimation techniques for MRgFUS thermal modeling applications.

Magnetic Nanoparticle-Assisted Microwave Hyperthermia Using an Active Integrated Heat Applicator

Magnetic nanoparticle (MNP)-assisted microwave hyperthermia using an active integrated heat applicator is presented in this paper. The effect of MNPs on microwave hyperthermia has been analyzed by coupled electromagnetic–thermal analysis considering the frequency- and temperature-dependent properties of biological tissues. For enhanced heating efficiency and material sensitivity, the optimum microwave frequency for hyperthermia has been identified using the presented analysis and confirmed with experiments. In order to demonstrate MNP-assisted hyperthermia, an active integrated applicator is developed. A microwave signal generation module, which has a voltage-controlled oscillator and a power amplifier, has been fabricated in monolithic microwave integrated circuits and integrated on the microwave heat applicator based on a spiral radiator. A dual-channel logarithmic power detector and a directional coupler have been also employed to monitor power levels during hyperthermia, which allows understanding of the heating mechanism. In vitro heating experiments on phantoms, pork muscles, and tumors with and without MNPs show a large difference in temperature rises, which demonstrates the effectiveness of MNPs for low-power and material-specific hyperthermia. Combined with MNP targeting on the cancer cells, MNP-assisted microwave hyperthermia can be a promising method for a low-power and cancer-specific treatment with minimal collateral damage.

Determination of Zearalanol and Its Analog Zearalanone in Muscle Tissues by Amplified Luminescent Proximity Homogeneous Assay (AlphaLISA)

A homogenous light-induced chemiluminescence immunoassay (AlphaLISA) method was established for the determination of residues of zearalanol and its analog zearalanone in muscle tissue samples. AlphaLISA is a bead-based proximity assay. When donor and acceptor beads proximity, a cascade of chemical reactions begin. The end result is a greatly amplified signal that contributes to the detection sensitivity down to the attomole level. Compared with other methods, the AlphaLISA has characteristics of homogeneity, being free of cleaning, high sensitivity. The method showed a linear relationship in the range of 0.01–4 ng/mL (R 2 > 0.99); the sensitivity of the assay was 0.066 ng/mL. Cross-reactivity rate of zearalanol was 100 % and zearalanone was 82.1 %, and other compounds were not more than 40 %. The average recovery rates of Zearalanol at spiked levels of 1–4 ng/mL were 96.3 to 105.0 and 91.7 to 100.5 % for pork and bovine muscles; the intra-day precision ranged from 2.6 to 9.8 %, and the inter-day precision ranged from 8.7 to 17.5 %. These results indicated that the proposed method was successfully applied in the analysis of zearalanol and its analog zearalanone in muscle tissues.

Influence of Duroc breed inclusion into Polish Landrace maternal line on pork meat quality traits.

Crossbreeding with Duroc breed allows to improve meat quality, but no data is available regarding specific influence of Duroc breed on characteristics of meat in the case of crossbreeding with various breeds. The aim of the present research was to evaluate the effect of crossbreeding Polish Landrace dames with Duroc sires on quality features of meat in reference to Polish Landrace breed. The objects of the study were Longissimus dorsi lumborum pork muscles obtained from Polish Landrace breed and Polish Landrace x Duroc crossbreed animals. Sarcomere length measurements were conducted using microscopic method and basic chemical composition measurement was analyzed using spectrophotometric scanning. Texture analysis of meat samples, performed after thermal treatment was expressed by Warner-Bratzler shear force and color analysis was obtained using CIE L*a*b* color system. No differences in sarcomere length, shear force as well as components of color values between pork meat originated from Polish Landrace breed and Polish Landrace x Duroc crossbreed were observed. Analysis of basic chemical composition revealed higher fat and lower ash contents in the case of meat of Polish Landrace breed animals. It was concluded that the actual impact of breed on meat characteristics is possibly altered by other factors. It may be suggested that influence of basic chemical composition on color of meat is breed-related.

LC-MS/MS による豚肉および豚肉加工食品中のクレンブテロール残留分析法

LC-MS/MS による豚肉および豚肉加工食品中のクレンブテロール残留分析法

Simultaneous determination of 22 cephalosporins drug residues in pork muscle using liquid chromatography-tandem mass spectrometry.

A simple, sensitive and reliable analytical method was developed for the simultaneous determination of 22 common cephalosporins from the first generation to the fourth generation in pork muscle by liquid chromatographic-tandem mass spectrometric (LC-MS/MS) method. Under the optimized extraction conditions, samples were directly purified through membrane filtration to separate all 22 cephalosporins and the critical pairs of each parent drug were completely separated. Variables affecting the LC-MS/MS were optimized to get a better separation. The excellent selectivity and sensitivity achieved in multiple reactions monitoring (MRM) mode allowed satisfactory confirmation and quantitation for the 22 cephalosporins. The linear range of the 22 cephalosporins is 0.06-100.0μg/L with good correlation coefficients (r(2)>0.9920). The limits of detection (LODs) and limits of quantitation (LOQs) of these compounds were in the range 0.04-3.0μg/L and 0.06-10.0μg/kg, respectively. The average intra-day recoveries at 3 spiked levels (LOQ, 2LOQ, 4LOQ) were all in the range 83.6-113.0% with RSDs (n=6) lower than 6.5%. The method of LC-MS/MS developed in this study was initially applied to the research of 22 cephalosporins in 12 retail pork samples and proved to be accurate, sensitive, minimum sample pre-treatment, convenient and practical.

Organic practices and gender are effective strategies to provide healthy pork loin

This study evaluated the influence of husbandry (organic feed and management but not free-ranging vs. conventional) and sex (barrows vs. gilts) on pork meat quality. A total of 60 Longissimus thoracis pork muscle samples from different 3-way crossbred genotypes were chosen from 3 conventional and 2 organic pig farms. Technological meat quality was measured at 24 h post-mortem and muscle fatty acid content and composition was analysed by gas chromatography. The loin from organic pigs at 24 h of retail display had lower pH, but it had no detrimental effects on drip loss. All the International Commission on Illumination colour attributes except meat lightness differed between husbandry systems. Moisture and crude protein content were lower whereas intramuscular fat content was greater in organic than in conventional pork. Total saturated fatty acid (SFA), monounsaturated fatty acid (MUFA), polyunsaturated fatty acid (PUFA) and PUFA n-6 contents did not differ between husbandry systems, but total PUFA n-3 (mainly C18:3 n-3) were greater in organic than in conventional pork. Sex did not affect ultimate pH or meat colour attributes but barrows showed lower moisture and greater intramuscular fat than gilts. Total SFA and MUFA content were similar but all the PUFA (both n-6 and n-3) were lower in barrows than in gilts. These results suggest that some bioactive compounds from dietary origin, i.e., linolenic acid (C18:3 n-3) content from dietary vegetable oils (soybean or olive olein), might be used to highlight the nutritive value of (not free-ranging) organic pork meat. In addition, gilts were leaner than barrows and showed a more favourable PUFA/SFA ratio.

Determination of 15 β-lactam antibiotics in pork muscle by matrix solid-phase dispersion extraction (MSPD) and ultra-high pressure liquid chromatography tandem mass spectrometry

An UPLC–MS/MS method based on matrix solid-phase dispersion (MSPD) was developed for simultaneous determination of 15 β-lactams in pork muscle. Muscle tissue was blended with Oasis HLB adsorbent. A column made from the sorbent/muscle tissue matrix was washed with hexane, after which β-lactams was eluted with acetonitrile/water (50:50, v/v) both containing 0.1% formic acid. The final extract was evaporated, and reconstituted into acetonitrile/water (10:90, v/v) for the analysis of UPLC-MS/MS. The correlation coefficient (r2) with each matrix-matched calibration curve is higher than 0.99. Limits of detection (LODs) and limits of quantification (LOQs) of β-lactams were ranged from 0.02 to 0.63 μg kg−1 and 0.07–0.97 μg kg−1, respectively. At the fortified levels, mean recoveries of all compounds were ranged from 92 to 111%, and the RSDs were lower than 12%. The method was accurate and reproducible, being successfully applied to the monitoring of 15 β-lactams in pork muscles obtained from the Chinese market.

A europium- and terbium-coated magnetic nanocomposite as sorbent in dispersive solid phase extraction coupled with ultra-high performance liquid chromatography for antibiotic determination in meat samples

A new magnetic dispersive solid-phase extraction approach based on Eu- and Tb-coated magnetic nanocomposites, combined with ultra-high performance liquid chromatography with fluorometric detection, is reported for the extraction and simultaneous determination of veterinary antibiotics. The method is aimed at monitoring of potential residues of three tetracyclines, namely oxytetracycline, tetracycline, chlortetracycline and three acidic quinolones, such as oxolinic acid, nalidixic acid and flumequine, chosen as model analytes, in animal muscle samples. The nanocomposites were obtained by synthesizing magnetic nanoparticles by a co-precipitation method and their coating with terbium and europium ions. The limits of detection obtained using standard solutions were: 1.0, 1.5, 3.8, 0.25, 0.7 and 1.2ngmL−1, which corresponds to 3.3, 5.0, 12.7, 0.8, 2.3 and 4.0μgkg−1 for oxytetracycline, tetracycline, chlortetracycline, oxolinic acid, nalidixic acid and flumequine, respectively, in meat samples. The precision values, obtained in the presence of the sample matrix, were in the ranges 0.12–2.0% and 2.6–15.4% for retention times and areas, respectively. The selectivity of the method was checked by assaying different veterinary drugs, finding that most of them did not interfere at the same concentration levels as that of analytes. A recovery study was performed in the presence of chicken and pork muscle samples, which provided values in the range of 61.5–102.6%.

Micro Electrical Impedance Spectroscopy (μEIS) Fabricated on the Curved Surface of a Fine Needle for Biotissue Discrimination

AbstractThis work presents a novel micro electrical impedance spectroscopy (μEIS) technique that can measure and discriminate the electrical signal responses of biotissues in real time. An EoN (EIS‐on‐a‐needle), EIS on the surface of a fine needle (400 μm in diameter), was fabricated using a newly developed flexible photomask film. The base material of the photomask is parylene‐C, which allows uniform contact on the curved surface of the needle; thus, the designed electrode patterns of the photomask can be transferred onto the needle surface with a high resolution (2.95 % or less in dimensional error). To validate the developed EoN as an electrical sensor, ex vivo experiments with various biotissues—butchered pork (skin, fat, and muscle) and human breast tissues (normal and cancerous)—were conducted by measuring real‐time electrical impedance during a frequency sweep. The conductivities (relative permittivity) of the pork tissues were evaluated by electrical equivalent circuit analysis: 56.6 mS/m (37,800), 68.0 mS/m (74,755), and 74.9 mS/m (26,145) for the skin, fat, and muscle, respectively. Moreover, the normal and cancerous tissues were well distinguished by electrical resistance at 4.04 kHz for various cancer grades (Elston grades 1, 2, and 3). Analysis of the electrical impedance suggests that the EoN can be utilized to diagnose the physiological states of biotissues in clinical use.

The influence of thermal processing on the fatty acid profile of pork and lamb meat fed diet with increased levels of unsaturated fatty acids

The research was carried out on 32 crossbred pigs of Polish Large White×Danish Landrace with Duroc and 80 rams, crossbreds of the Prolific-Dairy Koludzka Sheep with the Ile de France, a meat sheep. The fodder for the animals was enriched with the unsaturated fatty acids originated mainly from linseed and rapeseed oils. The fatty acid profile was determined in cooked longissimus lumborum, roasted triceps brachii and raw ripened rump from pigs as well as in grilled lambs' legs and their corresponding raw materials. Roasting caused the most pronounced increase of the saturated fatty acids and decrease in the polyunsaturated fatty acids of heated pork muscles. The smallest changes were observed in grilled lamb legs. The heating processes applied in this study, in most cases, did not cause essential changes in the indices of pro-health properties of fatty acid, therefore meat in the majority fulfil the latest recommendations of EFSA and FAO/WHO according to human health.

Effects of High Oxygen Packaging on Tenderness and Water Holding Capacity of Pork Through Protein Oxidation

The objective of this study was to investigate the biochemical difference of pork under high oxygen modified atmosphere packaging and their contribution to meat tenderness and water holding capacity of pork during postmortem storage. Twelve longissimus dorsi muscles were randomly assigned to either high oxygen modified atmosphere packaging or vacuum packaging and stored for 1, 4, and 6 days at 4 °C. The carbonyl content, protein surface hydrophobicity, protein solubility, calpain activity, desmin degradation, tenderness, and water loss of pork were determined. Results showed that carbonyl content, protein surface hydrophobicity, and protein solubility were significantly affected (P 0.05). Samples from high oxygen modified atmosphere packaging at 1 day showed greater intensity of intact 80 KDa calpain and lower intensity of autolyzed 76 KDa calpain product compared to samples from vacuum packaging (P 0.05). Higher intensity of intact desmin was observed in samples from high oxygen modified atmosphere packaging than vacuum packaging samples from 1 day of postmortem storage. Both packaging method and storage time showed significant effects (P < 0.05) on tenderness and water loss of pork muscle during postmortem storage. Changes in protein oxidation, calpain activation, and protein proteolysis of postmortem pork under high oxygen modified atmosphere packaging could help to explain decreased meat tenderness and increased centrifuge loss of pork.

Analysis of salt penetration enhancement in meat tissue by mechanical treatment using a tumbling simulator

Brining–tumbling is a key step in cured and/or cooked meat product manufacture. The massaging of meat enhances NaCl homogenization which, in combination with mechanical action, enhances protein solubilization. To clarify the underlying mechanisms and quantify their effects, meat tissue from Semimembranosus pork muscles was tested under various brining conditions: static brining (a), static brining after massaging (b), and brining–massaging (c). Using trials performed on a lab-scale tumbling simulator, massaging was controlled and characterized by three mechanical indexes. Apparent NaCl diffusivities (Dsalt) were estimated from measured NaCl profiles using Fick’s diffusion theory. It was demonstrated that tissue damage is not the main factor explaining salt migration enhancement: a-vs-b comparison showed a 20% increase in Dsalt, which was explained by observed microstructural changes. a-vs-c comparison showed a 200% increase in Dsalt, possibly due to water movement promoted by meat deformation. Calculations were used to compare spatial distributions of NaCl within small meat cubes during static brining versus brining–tumbling.

Curtailing Oxidation-Induced Loss of Myosin Gelling Potential by Pyrophosphate Through Shielding the S1 Subfragment.

In muscle food processing, where oxidation is inevitable, phosphates are usually added to improve water binding. This present study attempted to investigate the interactive roles of protein oxidation and pyrophosphate (PP) during thermal gelation of myosin. Myosin isolated from pork muscle was solubilized in 0.5 M NaCl at pH 6.2 then oxidatively stressed with an iron-redox cycling system that produces hydroxyl radicals with or without 1 mM PP and 2 mM MgCl2 at 4 °C for 12 or 24 h then heated to 50 °C at 1.3 °C/min. Protein conformational stability was measured by differential scanning calorimetry, and covalent cross-linking was examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis following chymotrypsin digestion. The binding of PP to myosin suppressed disulfide bond formation in myosin subfragments 1 and 2 and partially inhibited oxidation-initiated cross-linking of heavy meromyosin during myosin gelation with a lesser effect on light meromyosin. In the presence of PP, myosin exhibited less loss of conformational integrity upon oxidation than myosin without PP. Rheological analysis from 20 to 75 °C indicated up to 32% decreases (P < 0.05) in elastic modulus (G') of myosin gels due to oxidation. However, the presence of 1 mM PP, which also lowered the gelling capacity of myosin, inhibited the oxidation-induced G' by nearly half (P < 0.05). These results suggest that the protection of myosin head from oxidative modification by PP can be a significant factor for the minimization of gelling property losses during cooking of comminuted meats. The association of myosin S1 subfragment possibly S2 as well with pyrophosphate prevents extensive myosin head–head cross-linking. This alleviates the negative impact of oxidation on the gel formation of myosin, an expected main form of myofibrillar protein due to pyrophosphate-induced actomyosin dissociation. Likewise, oxidative S1–S1 association inhibits the binding of pyrophosphate thereby reducing its gel-weakening effect. The mutual constraining roles of oxidation and pyrophosphate can be a significant factor for the minimization of gelling property losses during the manufacture of comminuted meat products.

Estimation of Genetic Parameters for Pork Belly Components in Yorkshire Pigs.

This study was conducted to estimate the genetic parameters for pork belly traits and muscles in Yorkshire pigs. Each pork belly was cut into nine parts perpendicular to the thoracic vertebrae (6th to 14th). Traits of belly muscles including the deep pectoral, latissimus dorsi, cutaneous trunci, rectus abdominis, external and internal abdominal oblique from 382 purebred pigs were recorded and analyzed using SAS Package (9.1) and Derivative-free restricted maximum likelihood methods. Heritability estimates for belly traits ranged from 0.27 to 0.49, while they were 0.12 to 0.66 for belly muscles. Moderate to high heritability estimates were noted in belly weight (0.33), belly length (0.28), and belly width (0.49). In belly muscles, the latissimus dorsi and deep pectoral, which are located only in the 6th to 9th vertebrae sections, were found to have heritability estimates ranging from 0.21 to 0.29 and 0.23 to 0.35, respectively. Strong heritability estimates were observed in the 7th to 13th sections of cutaneous trunci muscle ranging from 0.42 to 0.66. Genetic correlations of latissimus dorsi m. with belly length were positive (0.50), while cutaneous trunci m. with belly weight also revealed a positive relationship that ranged from 0.35 to 0.47. The estimated genetic parameters indicate that belly weight can be improved by genetic selection. Differences in the levels of heritability occurred among various parameters of Yorkshire pork belly, which should be considered when performing selection to improve pork belly quality. Moreover, these results can provide valuable information that can be used as the basis for further investigations to improve pork belly.

Non-destructive salt content prediction in brined pork meat using ultrasound technology

This works aims to show the feasibility of using low-intensity ultrasound (US) to predict the salt content in brined Biceps femoris (BF) and Longissimus dorsi (LD) pork muscles. For this purpose, meat samples were salted in brine solution (20% w/w at 2°C) for different times (24, 48, 96 and 168h) and the US velocity measured before and after salting. In addition, model samples with preset water and salt contents were formulated and the US velocity was measured. In the model samples, the salt content (XS) had a more marked effect on the US velocity (13.0m/s per ΔXS=1% wet basis) than the water content (5.0m/s per ΔXW=1% wet basis). The salt gain and the water loss during brining caused the US velocity to increase (61.5 and 49.3m/s for 168h in LD and BF, respectively). Significant linear relationships between the US velocity and both factors (XS and XW) were established (R2>0.771). A predictive model of the salt content based on the US velocity was proposed; this was successfully validated (average estimation error 0.48%), which shows the feasibility of using US for industrial quality control purposes.

Multiresidue analysis of 63 veterinary drugs in meat by dispersive solid-phase extraction and high performance liquid chromatography-tandem mass spectrometry

A novel multiresidue analytical method has been developed and validated for the determination of five classes of veterinary drugs including 18 β-lactams, 15 quinolones, 21 sulfonamides, 3 sulfonamide potentiators and 6 antiparasitics in meat using dispersive solid-phase extraction (dispersive-SPE) and high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The analytes were extracted with a vortex mixer by 0.1 mol/L Na2 EDTA solution and acetonitrile containing 1% (v/v) acetic acid, and then the extracts were purified using dispersive-SPE with C18 sorbent. Electrospray ionization mass spectrometry was operated in positive mode using dynamic multiple reaction monitoring (DMRM) for the qualitative and quantitative analysis of the 63 analytes after the separation on a Poroshell EC-C18 column (100 mm x 2.1 mm, 2.4 µm). The correlation coefficients of linear calibration curves were over 0.99 in the corresponding concentration ranges. The average recoveries of the 63 analytes ranged from 62.2% to 112.0%, and the relative standard deviations (RSDs) were 3.1%-16.3% in spiked meat (pork, beef and chicken muscle) at three levels. The limits of detection (LODs, S/N ≥ 3) and the limits of quantification (LOQs, S/N ≥ 10) were 0.1-3.0 µg/kg and 0.5-10.0 µg/kg, respectively. The method is simple, rapid, sensitive, reliable and suitable for the determination of residues in animal products.

Comparison of iodine value equations among pork carcass fat depots of immunologically castrated pigs

cells transformed by a pET(21) plasmid containing the Shp gene and purified. Ability of apoShp to remove hemin from pork metHb was spectrophotometrically determined (n = 2) in solution by observing absorbance shifts from 405 nm (metHb peak) to 418 nm (holoShp peak) during incubation at 0.2 °C and pH 5.9. To investigate the significance of residual Hb in promoting lipid oxidation in pork muscle, the Semitendinosus was selected as a model muscle. The muscle was trimmed to select the red portion, ground with a 5 mm plate, and minced in a food processor. Heme content of the mince was determined by acid–acetone extraction. Lipid oxidation in stored mince (0.2 °C, pH 5.9, n = 2) with and without added apoShp was investigated by thiobarbituric acid reactive substances (TBARS) measurement. Statistical analysis employed the MIXED procedure of the SAS system. Results: Promotion of lipid oxidation in the mince was affected by the presence of 1.5% NaCl at 0.2 °C and pH 5.9. The 1.5% NaCl treatment achieved a significant increase in TBARS formation over the 0% treatment (P=0.0005). By 241 h of storage, TBARS in the 1.5% NaCl treatment reached 48.45 ± 2.45 μmol TBARS/kg mince, while TBARS in the 0% NaCl treatment reached 0.049 ± 0.069 μmol TBARS/kg mince, representing a 989-fold increase in TBARS formation (P b 0.0001). To determine the significance of residual Hb in promoting lipid oxidation in the mince, effect of a 2.5-fold excess of apoShp over total heme pigment content on TBARS formation in the mince was investigated in the presence of 1.5% NaCl. ApoShp significantly inhibited TBARS formation (P= 0.0019). By 131 h of storage, TBARS in the apoShp treatment reached 0.490 ± 0.690 μmol TBARS/kg mince, while TBARS in the apoShp-free treatment reached 9.129 ± 0.439 μmol TBARS/kg mince, representing a 95% inhibition of TBARS formation (P b 0.0001). To determine the ability of apoShp to remove hemin from pork metHb, a 4-fold excess of apoShp over metHb was incubated with pork metHb, in the presence of 1.5% NaCl. Evidenced by a shift in absorbance from 405 nm to 418 nm, apoShp removed increasing quantities of hemin from pork metHb over 91 h. Conclusion: These data suggest Hb, not Mb, as the primary promoter of lipid oxidation in pork Semitendinosus muscle, and reinforce the importance of residual blood in postmortem muscle as a target for antioxidant strategies.