Ochratoxin A in raw materials and cooked meat products made from OTA-treated pigs

The aim of this study was to determine ochratoxin A (OTA) concentrations in the raw materials and cooked meat products made from pigs sub-chronically exposed to OTA. The treated animal group (n = 5) was administered with 300 μg OTA/kg of feed for 30 days, whereas the control group (n = 5) was left untreated. OTA concentrations were quantified using immunoassay (ELISA) and high performance liquid chromatography with fluorescence detection (HPLC-FD). OTA concentration was the highest in the kidney, followed by the lungs, liver, blood, spleen, heart, and adipose tissue. As for the final meat products, the highest average OTA concentration was detected in black pudding sausages (14.02 ± 2.75 μg/kg), then in liver sausages (13.77 ± 3.92 μg/kg), while the lowest was found in pâté (9.33 ± 2.66 μg/kg). The results pointed out that a sub-chronic pig exposure leads to the accumulation of OTA in raw materials and consequently in meat products, whose level of contamination is directly dependent on OTA contents in raw materials used for their production.     

Salmonella in raw meat and by-products from pork and beef

After campylobacteriosis, salmonellosis is the second main cause of human bacterial enteritis in Germany. Salmonella is known to colonize the gastrointestinal tract of animals without producing any clinical signs. Therefore, carcasses can become contaminated with Salmonella at the time of slaughter. During an 11-month period, a total of 4,170 raw meat samples and by-products from beef and pork, obtained from seven different slaughterhouses in Southern Germany, were screened by the VIDAS system for Salmonella in this study. Positive results were confirmed by isolation of the pathogen on selective agars. The overall percentage of Salmonella-positive samples was 1.4% by the VIDAS system and 0.7% by culture confirmation. Salmonella was detected in 1.8% of pork samples by the VIDAS system and in 1.1% of samples by culture. In beef samples the presence of Salmonella was verified in 0.6% of samples by the VIDAS system and in 0.1% by culture on selective agars. The highest contamination rates were found in porcine and bovine tongue samples. Salmonella was detected in porcine samples throughout the year, except in samples collected in July, and a slight increase was observed in the colder months. The VIDAS system was shown to be an efficient screening method for the detection of Salmonella, with the advantage of a reduced analysis time.     

A comparison of the flavour volatiles from cooked beef and pork meat systems

The headspace volatiles from beef and pork cooked with and without added adipose tissue were entrained on Tenax GC before analysis by gas chromatography (g.c.) and combined gas chromatography-mass spectrometry. Lipid-derived volatiles dominated the headspaces of all samples and the only qualitative difference between beef and pork was an alkene of lipid origin which was peculiar to beef samples. A comparison of the areas of 37 g.c. peaks from replicate analyses of the different meat preparations using canonical variates and stepwise discriminant statistical techniques unambiguously distinguished the lean meats and the lean meats cooked with adipose tissue of either species. Adding adipose tissue to lean meat did not result in proportional increases in lipid-derived volatiles.     

The tenderness of cooked and raw meat from young and old beef animals

The shortening-toughness relationships for sternomandibularis muscles of young ox and large old bull have been compared. In both, toughness, measured by tenderometer, increases to a maximum at a shortening of 40%, and declines steeply from there at higher shortenings. This characteristic peaked relationship is obtained for ox and bull cooked both at 60 and 80 °C. However, toughness values for meat cooked to 60 °C are only about half those for meat cooked to 80 °C. In contrast to these similarities in the relationships for young and old animals, the rate of toughness increase with shortening in ox is considerably less than in bull. Thus toughness of ox at a given shortening and cooking temperature is considerably lower than that for bull, especially at high shortenings. A further distinction is made between the animals in that raw ox muscle does not give a peaked shortening-toughness relationship, whereas raw old bull does. The results have shown that for longissimus and sternomandibularis muscles a trained taste panel is only sensitive to variations in toughness in the lower half of the range of shear force values determined by tenderometer. In the light of this, live animal characteristics and muscle shortening are both important in determining toughness measured by taste panel.     

Biologically active polyamines in beef, pork and meat products: A review

Dietary polyamines (PAs) putrescine (PUT), spermidine (SPD) and spermine (SPM) participate in an array of roles in human metabolism. Nevertheless, under some physiological conditions they can be undesirable. Meat and meat products are among important sources of PAs in human nutrition, mainly of SPM. The usual contents of PUT, SPD and SPM in fresh beef and pork are <2, <5 and 20-40mgkg(-1), respectively. Current information on changes of PAs during meat storage corresponds with PUT formation by bacterial activity mainly of pseudomonads and Enterobacteriaceae. However, data on SPD and SPM changes during meat chill-storage have been inconsistent. Culinary processing of meat probably does not change SPD and SPM levels. PUT can be formed in different meat products in relation to the microbial population of the raw materials used and the hygienic level of manufacturing process. SPD and SPM contents seem to remain stable during processing of non-fermented meat products or decrease during dry-cured ham ripening. PUT contents increase commonly to 60-140mgkg(-1) in dry spontaneously fermented sausages, however, contents up to several hundreds mgkg(-1) are not extraordinary. Starter cultures are usually able to decrease PUT formation considerably. SPD and SPM contents in dry fermented sausages are comparable with levels typical for fresh meat. Data on SPD and SPM changes during ripening and storage are inconsistent. A decrease of the both polyamines during a storage period has been usually reported.     

Bifidobacterium species isolated from animal feces and from beef and pork meat

Bifidobacteria were isolated from 122 of 145 samples of animal feces (from cattle, swine, sheep, goats, horses, rabbits, chickens, geese, and pigeons) from farms in France and Austria and from 92 of 955 production and processing chain samples of beef and pork (obtained at slaughter, cutting, and retail). Bacterial strains were identified to species by phenotypic numerical classification based on API 50CH and ID 32A tests and DNA-DNA hybridization. Bifidobacterium pseudolongum was present in 81% (99 of 122 samples) of all Bifidobacterium-positive fecal samples and predominated in samples from all animal species except those from swine from Austria. In these Austrian swine samples, the majority of strains were identified as Bifidobacterium thermophilum (78%), followed by B. pseudolongum (48%). The distribution of B. thermophilum and B. pseudolongum differed significantly between Austrian swine and cattle samples such as those collected along beef and pork production and processing chains. Bifidobacterium animalis was isolated from swine feces, and Bifidobacterium ruminantium was isolated from cow dung. Six fecal isolates (from cattle, swine, rabbits, goats, and horses) were identified as belonging to Bifidobacterium species of predominantly human origin: B. adolescentis, B. bifidum, and B. catenulatum. Only one other species, Bifidobacterium choerinum, was detected with low frequency in a pork processing chain. B. pseudolongum subsp. pseudolongum was predominant in pig feces, whereas B. pseudolongum subsp. globosum was predominant in feces from other animal species. Four strains closely related to both subspecies (58 to 61% DNA reassociation) formed a distinct genomic group. PCR techniques, which are more rapid and sensitive than culture-based methods, could be used to detect directly B. pseudolongum and B. thermophilum as indicators of fecal contamination along the meat processing chain.     

Psychrotrophic clostridia causing spoilage in cooked meat and poultry products.

Certain types of commercially produced noncured turkey breast and roast beef are precooked in situ, stored at 4 degrees C or below, and typically given use by dates of greater than 50 days. While of rare, sporadic occurrence, an unpleasant spoilage characterized by strong H2S odor and gas production has been observed in these products. This spoilage is due to the growth of psychrotrophic anaerobic sporeformers. Isolates from roast beef resemble Clostridium laramie while isolates from uncured turkey have been designated C. ctm for cooked turkey meat. The turkey breast isolates were characterized by temperature growth ranges, carbohydrate fermentations, and other biochemical reactions. Growth of all isolates was inhibited in broth media by 3.0% NaCl, 100 ppm nitrite, 2.0% sodium lactate, or 0.2% sodium diacetate. Inoculated studies were performed with three isolates in cooked turkey product. All three isolates grew and spoiled product at 10 and 3.3 degrees C, and one isolate grew at 0.5 and -3 degrees C. Some differences in growth were observed with the lactate and diacetate treatments in turkey meat among the three isolates. One isolate appeared to utilize the lactate, two were inhibited. Overall, 0.1% diacetate consistently delayed growth, although to different degrees, for all isolates.     

Predicting pathogen growth during short-term temperature abuse of raw pork, beef, and poultry products: use of an isothermal-based predictive tool

A computer-based tool (available at: www.wisc.edu/foodsafety/meatresearch) was developed for predicting pathogen growth in raw pork, beef, and poultry meat. The tool, THERM (temperature history evaluation for raw meats), predicts the growth of pathogens in pork and beef (Escherichia coli O157:H7, Salmonella serovars, and Staphylococcus aureus) and on poultry (Salmonella serovars and S. aureus) during short-term temperature abuse. The model was developed as follows: 25-g samples of raw ground pork, beef, and turkey were inoculated with a five-strain cocktail of the target pathogen(s) and held at isothermal temperatures from 10 to 43.3 degrees C. Log CFU per sample data were obtained for each pathogen and used to determine lag-phase duration (LPD) and growth rate (GR) by DMFit software. The LPD and GR were used to develop the THERM predictive tool, into which chronological time and temperature data for raw meat processing and storage are entered. The THERM tool then predicts a delta log CFU value for the desired pathogen-product combination. The accuracy of THERM was tested in 20 different inoculation experiments that involved multiple products (coarse-ground beef, skinless chicken breast meat, turkey scapula meat, and ground turkey) and temperature-abuse scenarios. With the time-temperature data from each experiment, THERM accurately predicted the pathogen growth and no growth (with growth defined as delta log CFU > 0.3) in 67, 85, and 95% of the experiments with E. coli 0157:H7, Salmonella serovars, and S. aureus, respectively, and yielded fail-safe predictions in the remaining experiments. We conclude that THERM is a useful tool for qualitatively predicting pathogen behavior (growth and no growth) in raw meats. Potential applications include evaluating process deviations and critical limits under the HACCP (hazard analysis critical control point) system.     

PCR identification of beef, sheep, goat, and pork in raw and heat-treated meat mixtures

A PCR assay has been developed for the specific and qualitative detection of pork (Sus scrofa domesticus), beef (Bos taurus), sheep (Ovis aries), and goat (Capra hircus) in raw and heat-treated meat mixtures. A forward common primer was designed on a conserved DNA sequence in the mitochondrial 12S ribosomal RNA gene (rRNA), and reverse primers were designed to hybridize on species-specific DNA sequences of each species considered. The different sizes of the species-specific amplicons, separated by agarose gel electrophoresis, allowed clear species identification. Analysis of experimental meat mixtures demonstrated that the detection limit of the assay was 1% (wt/wt) for each species analyzed. This assay can be useful for the accurate identification of these species, avoiding mislabeling or fraudulent species substitution in meat mixtures.     

Salmonella surveillance in raw and cooked meat and meat products in the Republic of Ireland from 2002 to 2004

The food industry, under the regulation of the Department of Agriculture and Food (DAF) in the Republic of Ireland, is required to undertake all microbiological testing in relation to zoonoses control, in laboratories approved by DAF. These laboratories submit a monthly report of all tests undertaken, together with all presumptive Salmonella isolates for confirmation, typing and storage to the Central Veterinary Research Laboratory (CVRL). Details of Salmonella tests on 110,229 raw and 25,189 cooked meat samples from 25 laboratories were recorded over the 3-year period 2002-2004. Salmonella spp. were isolated from 1.0% of the 110,229 raw meat samples and 0.1% of the 25,189 cooked meat samples tested. The percentage of raw meat samples contaminated with Salmonella decreased over the three-year period from 1.2% to 0.9%. There was no seasonal trend in the isolation of Salmonella from any of the meats or meat products. Recoveries of the organism were highest for turkey and chicken meats at 3.1% and 2.8%, respectively, followed by porcine meats at 2.1%. The recoveries were much lower for ovine meats and meat products at 0.2% and bovine meat and meat products at 0.16%.     

Hygiene indicator microorganisms for selected pathogens on beef, pork, and poultry meats in Belgium

Several bacterial indicators are used to evaluate hygiene during the meat slaughtering process. The objectives of this study were to assess the Belgian baseline data on hygienic indicators and the relationship between the indicators and zoonotic agents to establish hygiene indicator criteria for cattle, pig, and chicken carcasses and meat. The study used the results from the official Belgian surveillance plan from 2000 to 2003, which included the monitoring of Escherichia coli counts (ECC), Enterobacteriaceae counts (EC), aerobic colony counts (ACC), and Pseudomonas counts (PC). The sampling method was the wet and dry swabbing technique for cattle and pig carcasses and neck skin excision for broiler and layer chicken carcasses. The 75th and 95th percentiles of ECC were -0.20 and 0.95 log CFU/cm2 for cattle carcasses, 1.20 and 2.32 log CFU/cm2 for pig carcasses, and 4.05 and 5.24 log CFU/g for chicken carcasses. The ACC were 2.1- to 4.5-log higher than the ECC for cattle, pigs, and chickens. For cattle and pig carcasses, a significant correlation between ECC, EC, and ACC was found. ECC for pork and beef samples and EC in pig carcasses were significantly higher in samples contaminated with Salmonella. In poultry samples, ECC were in general higher for samples containing Salmonella or Campylobacter. Thus, E. coli may be considered as a good indicator for enteric zoonotic agents such as Salmonella for beef, pork, and poultry samples and for Campylobacter in poultry samples.     

Determination of cholesterol oxidation products in raw and processed beef and pork preparations

The effect of pan-frying on the formation of cholesterol oxidation products (COPs) in different processed meat samples (beef patties, braised meat, and fillets of pork) was studied. Samples were pan-fried with or without addition of oil. Different unsaturated oils (olive oil, corn oil or partly hydrogenated plant oil) were used throughout the study. After extraction, seven toxicologically relevant COPs were analyzed using LC–MS. Prior to heat processing up to 6.7 mg COPs/kg extracted fat could be detected in the raw material. Neither the cholestanetriol nor 25-hydroxycholesterol, which are the most cytotoxic COPs in vitro, were detectable in any sample. Differences in the COPs contents were observed between beef (up to 16.5 mg/kg extracted fat) and pork (up to 22.2 mg/kg extracted fat) samples. In prepared samples higher COPs content was noted compared with raw samples. Generally, a certain order of COPs increase dependent on the plant oil used could be recognized: corn oil < partially hydrogenated plant oil < olive oil. It appears that short heating time, mild heating conditions, and the use of fresh and shortly stored raw materials keep COPs levels low.     

Cholesterol content and atherogenicity of fermented sausages made of pork meat from various breeds

Three batches of the Sremska sausage (traditional Serbian fermented sausage) were made: control variant (C) of a Landrace and the other two of primitive breeds: Mangalica (A) and Moravka (B), with the aim of determining the cholesterol content and the content of fatty acids. The cholesterol content in meat, fatty tissue and sausages was determined, in the case of the latter at the beginning of production (day 0), at the end of production (day 14) and after a storage period of the vacuumed product (day 60). The fatty acids content was determined at the beginning and at the end of production. Values were considered significantly different when p<0.05. The cholesterol content in meat (mg/100 g of a sample) ranged from 40.58 (B) to 51.54 (C), indicating a significant discrepancy in all samples. As for back fat, there was a notable disparity in cholesterol content between control and primitive breed samples (47.15 (C), 35.54 (B) and 36.41 (A)). The cholesterol content in sausages at the conclusion of the production ranged from 40.41 (A) to 43.33 (B), with no significant difference between the samples. After storage (day 60), the cholesterol content ran from 42.75 (A) to 52.41 (B), with no significant difference only between samples C and A. Fatty acids content was monitored via the index of atherogenicity, and the polyunsaturated/saturated fatty acids ratio. The index of atherogenicity at the end of production was the highest in sample A, 0.61, and significantly differs from other samples, while the lowest value was recorded in sample C, 0.46. PUFA/SFA at the end of production was the lowest in sample A (0.20), with none of the samples exceeding 0.4. No significant advantages of the use of the meat of primitive breeds were noted.     

Evaluation of safe food-handling instructions on raw meat and poultry products

Every year in the United States, millions of people become ill, thousands of people die, and substantial economic costs are incurred from foodborne diseases. As a measure to prevent foodborne diseases, since July 1994, the U.S. Department of Agriculture has required that safe food-handling labels be placed on retail packages of raw or partially cooked meat and poultry products. Through selected states' Behavioral Risk Factor Surveillance System (BRFSS) interviews, survey data were collected to determine the proportion of adults aware of the label and adults who reported changing their raw meat-handling practices because of the label. Fifty-one percent of the 14,262 respondents reported that they had seen the label. Of these, 79% remembered reading the label, and 37% of persons who reported that they had seen and read the label reported changing their raw meat preparation methods because of the label. Women were more likely than men to have read the label, as were persons who are at least 30 years of age compared to younger adults (P < 0.05). Both label awareness and risky food-handling behaviors increased with education and income, suggesting that safe food-handling labels have limited influence on consumer practices. Our results also suggest that the labels might be more effective in discouraging cross-contamination than in promoting thorough cooking practices. We suggest that the label is only one component among many food safety education programs that are needed to inform consumers about proper food-handling and preparation practices and to motivate persons who have risky food-handling and preparation behaviors to change these behaviors.     

Semiquantitative detection of male pork tissue in meat and meat products by PCR

Consumer awareness has increased concerning castration of piglets without analgesia or anaesthesia. On the other hand the occurrence of boar taint is not tolerated by consumers. Currently no reliable methods exist for the on-line detection of boar taint in the slaughterhouse or for genetic sexing of pigs. Therefore, as an alternative the detection of male pork meat was sought. Based on detection of a length polymorphism of the sex chromosomal amelogenin gene a reliable, specific and highly sensitive PCR method for qualitative and semi-quantitative determination of male pork tissue in meat and meat products was determined. A set of 25 male and 25 female meat samples could be correctly identified and mixtures with as little as 0.1% male meat content could be detected. Therefore the method can be used for production and control of specific meat products containing low amounts of male pork meat and thus avoiding boar taint.     

Vacuum skin packaging and its effect on selected properties of beef and pork meat

Physicochemical, instrumental and microbiological examinations of steaks of beef and pork (m. longissimus lumborum) in vacuum skin packaging (VSP), conventional vacuum packing (CVP) and modified atmosphere packaging (MAP) were performed. Samples were stored at 2 ± 0.5 °C for 3 (pork) or 5 (beef) weeks. No statistically significant changes in pH values were recorded. Statistically significant (p < 0.001) changes in the thiobarbituric reactive substances content in modified atmosphere packed beef samples, and differences between samples in MAP and VSP or CVP were found from week 2 of the experiment onwards. The biggest changes in colour parameters were found in beef samples in MAP. The lowest and highest purge loss was recorded in samples in VSP and CVP, respectively. Vacuum packing enhanced the growth of lactic acid bacteria (LAB). At the end of the experiment, their numbers ranged from 4.31 log₁₀ cfu g^?1 (pork in CVP) to 5.14 log₁₀ cfu g^?1 (beef in VSP). LAB populations reached 2 log₁₀ cfu g^?1 in MAP beef and pork samples. On the other hand, MAP enabled the development of bacteria of the genus Pseudomonas and Brochothrix thermosphacta. The highest increase in coliform bacteria counts was recorded in vacuum-packed pork.     

Effects of salt reduction on the rheological and gelation properties of beef, pork and poultry meat batters

The gelation and rheological properties of beef, pork and poultry meat batters as affected by salt reduction (2·50, 1·25 and 0·00%) were studied by using a Haake rotational viscometer and a thermal scanning rigidity monitor. Beef batters showed a decrease in shear stress with the decrease in salt levels at both high and low shear rates. Pork batter showed a mixed behavior (no definite trend in shear stress versus shear rate) and the poultry meat batters showed a Bingham pseudoplastic behavior, except for the no-salt treatment. During heating the beef batters showed the highest G values followed by the pork and the poultry meat batters. The rigidity modulus profiles exhibited two major transition temperatures at 47-53°C and at 64-76°C. Beef batter with 2·50% salt developed the highest average G value (16·6 kPa) and the poultry batter with 2·50% salt the lowest (7·3 kPa).     

A SYBR Green real-time PCR assay to detect and quantify pork meat in processed poultry meat products

Species identification in meat products has grown in interest in recent years since these foodstuffs are susceptible targets for fraudulent labelling. In this work, a real-time PCR approach based on SYBR Green dye was proposed for the quantitative detection of pork meat in processed meat products. For the development of the method, binary meat mixtures containing known amounts of pork meat in poultry meat were used to obtain a normalised calibration model from 0.1 to 25% with high linear correlation and PCR efficiency. The method revealed high specificity by melting curve analysis, being successfully validated through its application to blind meat mixtures, which confirmed its adequacy for pork meat determination. The fully applicability of the method was further demonstrated in commercial meat products, allowing verification of labelling compliance and identification of meat species in processed foods.     

Isoelectric variants of actin in raw and cooked meat

Isoelectric focusing of myofibrillar proteins from raw meat gave one major and several minor actin bands. Extending the time, or raising the temperature, of a heat treatment progressively increased the proportion of variants of isoelectric point lower than the primary component. Because of the concomitant release of ammonia on heating, it was concluded that these variants arose from the hydrolysis pf amide groups of asparagine and/or glutamine. Determination of the relative proportion of deamidated actin components may provide a measure of the severity of heat treatment given to a sample of cooked meat.     

腌制肉品的基本工艺

<正> 将食品以特殊的香辛料腌制后煮熟,即成为一系列既容易烹煮又营养丰富的菜肴。消费者购买这些食品后,只需短暂的加热即可食用,大大满足了今天高速生活节奏的市场要求。 可用以进行腌制的肉品有很多,最常用的是牛肉、鸡肉、海产品和其他禽肉类产品。一般生产腌制食品的工序包括真空翻滚、烤炉蒸煮、切割、冷冻和包装等,所用的机械设备则因应所要求的制成品而定。