Cooked Pork Research Articles

The role of P450IIE1 protein and mRNA expression in determining adipose tissue skatole level

High concentrations of skatole in adipose tissue are a major factor in boar taint - the offensive odor and taste in cooked pork from some intact male pigs. Skatole is produced by bacterial fermentation of tryptophan in the large intestine, absorbed into the blood and transported into the liver, where it can be metabolised via the cytochrome P450 system. One reason for high skatole levels in pig adipose tissues could be low expression of hepatic cytochrome P450IIE1 in liver and hence a reduced rate of skatole clearance, but no correlation was found between the rate of skatole metabolism and the P450IIE1 content of isolated liver microsomes. The present study re-investigates the relationship between backfat skatole, liver P450IIE1 expression and the rate of microsomal skatole metabolism in two breeds of pigs.

Two-fibre solid-phase microextraction combined with gas chromatography–mass spectrometry for the analysis of volatile aroma compounds in cooked pork

The volatile aroma compounds in cooked pork were examined using solid-phase microextraction (SPME). Two SPME fibres coated with different stationary phases were used simultaneously to collect aroma compounds from the headspace above the pork. One fibre was coated with 75 μm. Carboxen–polydimethylsiloxane and the other was coated with 50/30 μm divinylbenzene–Carboxen on polydimethylsiloxane. After extraction, the two fibres were desorbed in the injection port of a gas chromatograph sequentially, so that the aroma compounds from both of the fibres could be analysed in one gas chromatogram. This procedure resulted in a chromatogram containing a more complete aroma profile for cooked pork than the chromatograms from either of the fibres on their own. Thirty-six compounds were identified in cooked pork for the first time.

Vancomycin-resistant enterococci isolated from animals and food

One hundred and one chicken products, boiled ham and turkey cold meat were acquired from 18 different supermarkets in Spain during October 1997 to June 1998 and were analyzed for vancomycin-resistant enterococci (VRE). In the same way, 50 intestinal chicken samples from a slaughterhouse were also studied. VRE were detected in 25 of 92 samples of food of chicken origin (27.2%), but no VRE were found in cooked pork or turkey products. VRE were also detected in 8 of 50 intestinal chicken samples from the slaughterhouse (16%). VRE were identified as Enterococcus durans ( n=11), Enterococcus faecalis ( n=10), Enterococcus faecium ( n=10) and Enterococcus hirae ( n=2). All these strains were characterized as belonging to the vanA genotype by polymerase chain reaction. Ampicillin, quinupristin/dalfopristin and high level aminoglycoside resistance were frequently found among these strains. Heterogeneity was observed in susceptibility patterns among VRE strains, even in those of the same species. The high rate of colonization of chicken products by vanA containing enterococci detected 6 months to 1 year after the banning of avoparcin as a growth promoter, supports other studies suggesting that the food chain could be a source of VRE colonization in humans and thus a source of VRE infections.

Color changes in irradiated cooked pork sausage with different fat sources and packaging during storage

Pork sausages were prepared with lean pork meat, fat from different sources [backfat (BF), corn oil (CO) or flaxseed oil (FO); 10% of lean meat], NaCl (2%), and ice water (10%). The emulsified meat batters were stuffed into casings (3 cm in diameter) and cooked to an internal temperature of 72°C. Cooked sausages were sliced and vacuum- or aerobic-packaged individually. Sausages were irradiated at a 0, 2.5, or 4.5 kGy dose and stored in a 4°C refrigerator for 8 days. Aerobic-packaged, irradiated cooked sausages prepared with BF and FO showed higher Hunter L-values than nonirradiated controls at day 0, but the difference disappeared at day 8. Irradiation increased the Hunter a-value in vacuum-packaged cooked pork sausages regardless of the fat source used, and the increase of the Hunter a-value was dose-dependent. In contrast, the Hunter a-value decreased by irradiation in aerobic-packaged cooked pork sausages prepared with BF or FO. The Hunter a-value of cooked pork sausage with aerobic packaging was significantly reduced at day 8. Hunter b-values increased at Day 8 in irradiated cooked pork sausages except for the sausage prepared with CO at 2.5 kGy. Cooked pork sausages prepared with CO were lighter, and sausage prepared with FO was redder and more yellow ( p<0.05) in vacuum packaging.

Prevalence of Toxoplasma gondii in Finishing Pigs in a Large-scale Farm in the Czech Republic

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Advice on the Design and Analysis of Sensory Evaluation Experiments Using a Case-study with Cooked Pork

Certain sensory evaluation experiments (e.g. taste panels) lead to data on an ordinal scale. Judges can typically only assess about six samples at each session before their ability to discriminate declines considerably. Thus allowance must be made for effects due to judge, session and order of tasting as well as treatment. We exemplify analysis-of-variance techniques where the basic observation is either a single assessment by a judge, the arithmetic mean over judges or a trimmed mean over judges. We also consider a linear logistic model. This specifically accounts for the ordinal nature of the data but the analysis and assessment of the goodness of fit by using residuals are more difficult.

Culinary herbs inhibit lipid oxidation in raw and cooked minced meat patties during storage

The effect of dried spices and the ethanol extract of those spices was studied on the stability of fresh chicken minced meat, and fresh and cooked pork patties pretreated with NaCl during refrigerated and frozen storage. The antioxidant activities of the spices were measured by thiobarbituric acid reactive substances (TBARS) and peroxide value (POV) in meat samples. The lipid oxidation was effectively inhibited in the chicken meat treated with several dry spices diminishing the TBARS to a range of 32% and 83% of those found in the control samples in frozen stored meat for 6 months. Marjoram, wild marjoram and caraway were the most effective dry spices. Ethanolic extracts of the same spices were more potent as antioxidants by lowering the concentration of the TBARS to a range of 20–27% of those found in the control samples. Addition of sodium salt to the minced pork resulted very high concentrations of the oxidation products originated from the polyunsaturated fatty acids. The treatment with ethanolic extract of spices (sage, basil, thyme and ginger) significantly inhibited the lipid peroxidation in refrigerated and chilled pork patties pretreated with NaCl by reducing both POV and TBARS. Heat treatment with microwaves produced significantly elevated levels of both lipid peroxides and TBARS, but the amount of these oxidation products was less than 10% in spice-treated salted meat samples compared to that in untreated ones. Lipid peroxidation also grew continuously during the storage period at −18°C in raw and cooked samples. Ethanolic extracts of spices had a very strong antioxidative effect inhibiting lipid peroxidation in heat-treated meat products during frozen storage. The highest antioxidant activity was observed in the case of ginger. High correlation coefficients were found between TBARS and POV both in raw and cooked pork patties (0.86, 0.91, respectively) during frozen storage. It is supposed that these compounds originated from the polyunsaturated fatty acids during oxidation processes but at different stages. Utilization of spices, spice mixtures or spice extracts in semi-prepared meat products intended to be frozen for up to 6 months or more before consumption is proved to be advantageous in regard of shelf life of the food, as well as of human health, because of the beneficial effect of spices in inhibition of lipid peroxidation during heat treatment and chilling storage. © 1999 Society of Chemical Industry

Lipid Oxidation, Volatiles and Color Changes of Irradiated Pork Patties Affected by Antioxidants

ABSTRACTChanges were measured in TBARS, color, and volatiles of irradiated (4.5 kGy) pork patties with antioxidants (sesamol, quercetin, rutin, BHT, and rosemary oleoresin) during 7 days storage at 4°C. Irradiation accelerated lipid oxidation of raw pork during storage. However, irradiation before cooking did not influence lipid oxidation of cooked pork during storage. Sesamol, quercetin, and BHT were effective in both irradiated raw and cooked pork during 7‐days storage. Rosemary oleoresin and rutin were effective only in irradiated raw pork for 3 days. Hexanal, propanal and higher boiling components were well correlated (P &lt; 0.01) with TBARS in cooked pork. Generation of volatiles was reduced by sesamol and quercetin, but the effects of antioxidants on color changes of raw pork patties were minor and inconsistent.

Effects of the halothane genotype and slaughter weight on texture of pork.

The objective of this study was to investigate the effects of the halothane (HAL) genotype, slaughter weight (SW), and the HAL x SW interaction on compositional and textural traits of raw and cooked pork. Pigs were bred to exhibit one of the three HAL genotypes (NN, Nn, and nn) with otherwise equivalent genomes. The nn halothane reactors are known to typically produce PSE pork, whereas NN pigs do not typically produce PSE pork. Pietrain x Large White gilts and boars, all with verified Nn genotype (by DNA test), were mated to obtain F2 littermates of the three HAL genotypes. These pigs were slaughtered at either 101 +/- 3 ("light") or 127 +/- 3 ("heavy") kg BW and were evaluated for longissimus muscle traits. The pH at .5 h after death (pH1) was 6.35, 6.13, and 5.68 in NN, Nn, and nn pigs, respectively. Sarcomere length was greater in nn than in NN and Nn pigs (1.94 vs 1.83 and 1.85 microm, respectively). Mechanical resistance was higher in nn than in NN pigs for both raw and cooked meat. Meat from nn pigs was judged by a trained panel to be less rough, more cohesive, harder, more fibrous, less granular, more elastic, and less easy to swallow than meat from NN pigs. For most traits under study, the heterozygotes were intermediate between the homozygotes but closer to NN than to nn pigs. Muscle from heavy pigs had longer sarcomeres and less moisture than muscle from light pigs. The n allele of the HAL gene unfavorably affects pork texture, and this effect is maintained throughout the range of 101 to 127 kg BW.

Application of the bacteriocinogenicLactobacillus sakeiCTC494 to prevent growth of Listeria in fresh and cooked meat products packed with different atmospheres

The production of sakacin K byLactobacillus sakeiCTC494 at different temperatures and pH was evaluated before its application as a bioprotective culture againstListeriain different meat-based food packaging systems, that is, oxygen-permeable film, under vacuum and under a modified atmosphere (20% CO2: 80% O2) and stored at 7°C. TheLactobacillusculture produced the bacteriocin at a range of temperatures from 4°C to 30°C and at initial pH from 5·5 to 6·5.Listeriainhibition in raw minced pork, poultry breasts and modelized cooked pork could not be achieved by the sole application of vacuum or a modified atmosphere. Inoculation ofLb. sakeiCTC494 or sakacin K inhibited the growth ofListeriato different extents in all the products studied in each system; the greatest inhibition being observed in the vacuum packaged samples of poultry breasts and cooked pork, and in the modified atmosphere packaged samples of raw minced pork. Addition of sakacin K resulted in immediate bactericidal action againstListeriain every product and atmosphere studied.

Oxidative stability and dietary treatment with vitamin E, oleic acid and copper of fresh and cooked pork chops

Research has been conducted on the effects of feed supplementation with vitamin E, oleic acid (sunflower oil) and copper on some quality characteristics of pork chops. The study was based on the measurement of pH 45′ and 24 hr post mortem, proximate composition, colour both objective and sensory, colour stability after packing in oxygen permeable film and protective atmosphere, copper and iron contents, vitamin E content in fresh and cooked chops, peroxide and TBARS value in raw and cooked meat, total cholesterol, cholesterol oxides and aldehydes in cooked meat, sensory evaluation of the eating quality of cooked chops and iodine number of subcutaneous fat. Vitamin E content was significantly higher with oil and vitamin supplementation. No variation has been observed in copper and iron contents. A higher stability of the colour of meat packed under modified atmosphere has been observed with increasing vitamin E content, but the same did not apply with meat packed in oxygen permeable film. No differences have been observed on fatty acid oxidative stability of fresh m. longissimus dorsi and cooked chops (peroxide and TBARS values), on cholesterol oxidation and aldehydes production of cooked chops with increasing vitamin E content. Iodine number in supplemented animals reached levels normally considered at risk for fat firmness.

Lipid Oxidation in Cooked Pork as Affected by Vitamin E, Cooking and Storage Conditions

ABSTRACTThe individual and combined effects of muscle vitamin E level, cooking conditions (duration, temperature and rate) and packaging on lipid oxidation in refrigerated cooked pork were examined. Oxidative stability following cooking was higher in pork with a higher vitamin E level (p&lt;0.01), cooked at a lower cooking temperature (p&lt;0.01), cooked for a shorter time (p&lt;0.01), cooked at a faster cooking rate (p&lt;0.05) or stored in vacuum packs (p&lt;0.01). Significant two‐way and three‐way interactions were observed between the effects of muscle vitamin E level, cooking conditions and packaging on lipid oxidation. Adopting more than one of these approaches to minimize lipid oxidation was more effective than adopting a single approach.

Monoclonal Antibodies to Porcine Thermal‐Stable Muscle Protein for Detection of Pork in Raw and Cooked Meats

ABSTRACTFour hybridoma cell lines secreting monoclonal antibodies (MAbs) specific to porcine thermal‐stable muscle proteins (TSMPs) were developed. The MAbs reacted with three protein bands (20.5, 22 and 24 kD) from raw pork extract; the protein band (24 kD) which was also present in cooked pork was identified as porcine‐specific TSMP. Epitope analysis indicated four MAbs recognized same or closely located antigenic sites on the pork TSMP. The developed MAb‐based indirect enzyme‐linked immunosorbent assay (ELISA) enabled the detection of pork in raw and cooked heterogeneous meat mixtures as low as 10 g/kg. The curvilinear relations of second‐degree polynomial (r2 &gt; 0.995) between pork concentrations and ELISA responses enabled quantifying degree of adulteration of pork in meat products.

Mechanical and structural characteristics of single muscle fibres and fibre groups from raw and cooked pork longissimus muscle

The aim of this study was to analyse the mechanisms that determine why small groups of muscle fibres may have different mechanical properties than single muscle fibres. The method used combined light microscopy and tensile testing on single fibres and small groups of fibres from raw and cooked (80 °C) meat, from both conditioned and unconditioned porcine longissimus muscle. The results showed that small groups of fibres had different breaking properties than constituent single fibres in raw muscle, but that these differences diminished on cooking. Raw groups of fibres showed a more uniform lengthening along their entire length and a higher extension to rupture than single fibres. Conditioning increased maximum strains in both single fibres and small fibre groups. In unconditioned cooked meat, single fibres and fibre groups showed comparable breaking stresses and extensions. Conditioning resulted in a lower strength in fibre groups than in single fibres. These results show that (endomysial) connective tissue linkages between adjacent muscle fibres in a small group significantly alter the breaking behaviour of single fibres. The effects of these connective tissue linkages are not reduced by conditioning alone, but are largely diminished by cooking to 80 °C.

Freeze/thaw Stability of Cooked Pork Sausages as Affected by Salt, Phosphate, pH, and Carrageenan

ABSTRACTThe effects of κ, ι, or λ carrageenan (CGN), sodium tripolyphosphate (STPP), chloride salts, and meat pH on the freeze/thaw stability of cooked pork sausages were investigated. STPP decreased thaw drip (TD) and increased hardness for all treatments regardless of type of salt or CGN. KCI did not affect the texture of control samples in the presence of STPP, but decreased the functionality of κ‐ and ι‐CGN. Increased meat pH increased the hardness and decreased thaw drip for all CGN treatments, except for λ‐CGN, which remained unchanged. k‐ and ι‐ CGN increased moisture retention of sausages prepared from low‐pH meat.

Oral allergy syndrome after ingestion of salami in a subject with monosensitization to mite allergens

The bulk of reports of side chain-specific [Mactam allergy have emanated from Spain and involve the aminopenicillins, ampicillin and amoxicillin. 3, 4 Fewer reports relate to cephalosporins, and a literature search revealed only one such report from North America. 5 Interestingly, this report was of four cases of anaphylaxis to intravenous cefazolin given before surgery. A number of conclusions can be drawn from this report: (1) side chain-specific cefazolin allergy appears to be uncommon (0.1% or less); (2) the incidence of false-positive intradermal cefazolin skin test results (1 mg/ml) is low; (3) a positive cefazolin skin test response, especially in conjunction with a history of a clinical reaction to cefazolin, should be considered highly clinically significant; and (4) an isolated positive cefazolin skin test response warrants additional skin testing and oral or parenteral challenge testing to identify side chain-specific allergy with good tolerance to other 6-1actams.

Effect of Frying on the Fatty Acid Profile of Some Meat Dishes

The purpose of this work was to study the effect of a culinary process, deep-fat frying, on fatty acids profiles of different meat dishes. Content in fatty acids in three meat dishes (chicken breast, pork steak, and pork loin), before and after deep-fat frying, was analyzed. Results showed an increase in almost all fatty acids, especially linoleic acid, due to absorption of part of the oil used (sunflower oil). Palmitoleic acid increased very little and remained at low concentrations. A decrease in relative percentage of saturated fatty acids (SFA) and an increase in polyunsaturated fatty acids (PUFA) was found in all dishes giving rise to more favorable ratios of cis PUFA/SFA and cis PUFA/(SFA-C18:0). The monounsaturated percentage increased lightly in cooked pork loin, whereas it diminished in chicken breast and pork loin.

Biogenic Amine Sources in Cooked Cured Shoulder Pork

Changes in biogenic amines were followed during pork meat storage, the manufacturing process, and the storage of cooked cured pork shoulder to establish the sources of these amines in this type of product. Microbial counts were also followed. During storage of pork meat at 6−8 °C, spermidine remained constant, spermine slightly decreased, and amounts of histamine, tyramine, putrescine, and cadaverine appeared. Significant correlation coefficients were obtained between aerobic total counts and tyramine, putrescine, and cadaverine. A biogenic amine index calculated from the sum of cadaverine, putrescine, tyramine, and histamine seemed to be useful as an indicator of the meat freshness. Spermidine and spermine initially present in meat used as raw material remained constant during the processing and the storage of the cooked pork shoulder. No additional biogenic amine formation was observed. Results of our work confirmed that only spermine and spermidine should be present in cooked pork shoulder, if fresh po...

Survival of Listeria monocytogenes and Salmonella typhimurium and Quality Attributes of Cooked Pork Chops and Cured Ham after Irradiation

ABSTRACTCooked pork chops (pumped with salt/polyphosphate brine or untreated) and cured hams were inoculated with Listeria monocytogenes and Salmonella typhimurium. The samples were irradiated at low (0.75 to 0.90 kGy) or medium doses (1.8 to 2.0 kGy), and each dose was delivered at either a low (2.5 M/min conveyor speed) or high (5.4 M/min) dose rate. Low‐dose irradiation reduced L. monocytogenes by more than 2 log and S. typhimurium by 1 to 3 log. Pathogen populations and total plate counts (TPC) were reduced to undetectable levels by medium doses. No meat quality attributes were affected, and no dose rate effect was observed. Nitrite reduced (P &lt; 0.05) both pathogens and TPC during 7°C storage in ham, especially when combined with low‐dose irradiation.

Behaviour of foodborne pathogens in cooked liver sausage containing lactates

Previous reports from our laboratory showed sensitivity of Listeria monocytogenes to lactates in cooked pork liver sausage. Further studies were undertaken to explain the antilisterial effects and to examine the sensitivity of Escherichia coli O157:H7 and Salmonella typhimurium strains to lactates. To determine the effect of heat treatment on the antilisterial activity during storage at 5 and 20°C, 3% sodium or calcium lactate (NaL or CaL) were added to sausage emulsion, followed by (1) sterilization (121°C, 15 min); (2) processing in a water bath to internal temperature of 70°C; or (3) added to ready-to-eat sausage (no additional heat treatment). Inhibition of L. monocytogenes strain Scott A was highest after heat sterilization and storage at 5°C. Growth of S. typhimurium and E. coli O157:H7 was abated in sterilized sausage by 3% NaL and CaL. Changes in log cfu g−1 after 4 days at 20°C were (1) L. monocytogenes: control, 5·96; 3% NaL, −0·17; 3% CaL, −0·77; (2) E. coli: control, 4·01; NaL, 0·34; CaL, −0·06; (3) S. typhimurium: control, 3·92; NaL, 1·14; CaL, 0·92. While CaL was consistently more effective than NaL, examination of other calcium salts (carbonate, chloride, citrate and phosphate, dibasic) confirmed that lactate is the principal antibacterial factor.