Iron and zinc compounds in the muscle meats of beef,lamb, pork and chicken

Beef, lamb, pork and chicken leg muscles were extracted with distilled water and the soluble iron and zinc compounds separated by gel filtration and dialysis. Iron was distributed between five main components: an insoluble fraction, ferritin, haemoglobin, myoglobin and a low molecular weight fraction. In beef and lamb, myoglobin was the predominant iron compound but in pork and chicken, most of the iron was associated with the insoluble fraction. Whereas more than 70% of beef iron was associated with the haemoproteins, haemoglobin and myoglobin, less than 30% of chicken iron was in this form. Even so, in all meats most of the soluble iron was associated with the haemoproteins. Zinc was present mainly in the insoluble fraction. The soluble zinc was distributed between five main components. Over 70% of soluble zinc was associated with two components having molecular weights of 65 000 and 35 000. The nature and availability of zinc and iron in the various meat fractions is discussed.     

北京地区牛、羊肉片中鸭、鸡、猪源性成分调查

建立生肉制品中鸭、鸡、猪源性成分的荧光PCR检测方法,对北京地区出售的牛、羊肉片进行成分调查。方法 合成检测鸭、鸡、猪源性成分的特异性引物和探针,建立实时荧光PCR检测方法,测定方法的特异性、灵敏度,在北京部分超市、农贸市场、餐馆采集牛、羊肉片进行成分调查。结果 所建立的实时荧光PCR方法对鸭、鸡、猪源性成分具有较好特异性,与常见食用肉类DNA在Ct 30以内无交叉反应;对混合肉中鸭、鸡、猪成分DNA的检出限是0.1%。北京市场上采集的86份牛、羊肉片中,30份检出上述成分,占34.9%;羊肉片的掺假率高于牛肉片;农贸市场采集样品掺假率明显高于超市和餐馆。结论 所建生肉制品中鸭、鸡、猪源性成分的检测方法简单、特异,对样品的检测结果显示,北京市售牛、羊肉中存在掺入鸭、鸡、猪肉的现象。     

Identification and stability study of irradiated chicken,pork, beef,lamb, fish and mollusk shells by electron paramagnetic resonance (EPR) spectroscopy

The application of electron paramagnetic resonance (EPR) spectroscopy to the detection of irradiation treatment of bones of chicken, pork, beef, lamb, fish and mollusk shells was described. Induced radicals in irradiated samples gave distinguishable EPR patterns for differentiation from the unirradiated samples. The EPR signals were found to be relatively stable in mammalian bones and mollusk shells; but significant loss was observed in fish samples. Dose–response relationships of the samples were found to be linear at 0–5 kGy range (r ²>0.95). Using calibration curve method, the irradiation status of all the 64 blind samples (14 unirradiated and 50 irradiated) was correctly identified. The estimation of irradiation doses was satisfactory with mean values ranging from 86 to 116% of those of the nominal values, and precision (%RSD) ranged from 15 to 29%. The validated analytical procedure was applied in the surveillance monitoring of about 400 food samples during the period of 2001–2004.     

变频与传统微波加工中猪、牛、羊、鸡、鸭肉的蛋白质成分对比及组织结构

使用传统微波炉和变频微波炉分别对猪肉、牛肉、羊肉、鸡肉、鸭肉原料进行蒸煮加工,测定肉制品的蒸煮损失率、可溶性蛋白质、氨基酸价指标,然后使用扫描式电子显微镜、质构仪对肉样品进行组织、质构方面的分析,阐明变频微波和传统微波加工的的肉制品的营养差异原因。     

Evaluation of a conductance method for enumerating Escherichia coli on chicken, pork, fish, beef, and milk

Experiments were conducted to evaluate a rapid method for enumerating Escherichia coli on food products of animal origin. In study I, rinses from samples of chicken, ground beef, pork, and fish and samples of milk were inoculated with various levels of actively growing E. coli. Conductance assays were monitored at 44 degrees C on each sample using coliform medium supplemented with 2% dextrose. High correlations between E. coli concentrations and E. coli conductance detection times (ECDTs) were found (r = -0.97 to -0.99) for all foods tested in all replicates; however, in most cases, the concordance correlation coefficients (r(c)) were low, indicating a lack of predictive accuracy. In this study, low accuracy of the conductance method for estimating E. coli counts was attributed to use of concentrations of E. coli that exceed 10(6) CFU/ml, the detection threshold of the instrument. Slopes of the linear regression lines (E. coli concentration vs. ECDT) for each type of food tested were not significantly different (P < 0.0001), indicating that a single regression equation may be used to estimate E. coli counts for all of the types of food tested in 1 to 7.5 hours using ECDT. In study II, ECDTs for pork, fish, beef, and milk significantly (P < 0.05) decreased in a linear manner as time of temperature abuse increased. Although the ECDT for chicken decreased linearly, no significant differences were observed between 3 and 6 or between 9 and 12 h of abuse. These data demonstrate a strong relationship between increasing populations of E. coli due to temperature abuse and decreasing ECDT. Therefore, results from both studies indicate that this method could be useful for estimating naturally occurring populations of E. coli on foods of animal origin.     

Fatty acid content and composition of english beef, lamb and pork at retail

We have determined the fatty acid content and composition of retail samples of meat and assessed them with respect to UK dietary recommendations. Fifty beef sirloin steaks, pork chops and lamb chops were purchased from four supermarkets on separate occasions. The percentage of muscle (boneless basis) in the samples was 84.4 ± 4.3, 69.8 ± 7.7 and 78.9 ± 7.1 for beef, lamb and pork, respectively, with fatty acid contents of 3.84 ± 1.3, 4.73 ± 1.66 and 2.26 ± 0.7 g per 100 g muscle, respectively. Adipose tissue fatty acid contents were 70.0 ± 8.2, 70.6 ± 8.6 and 65.3 ± 9.4 g per 100 g tissue. A range of C20 and C22 polyunsaturated fatty acids (PUFA) was present in the muscle of all three species and pork adipose tissue but their concentrations in lamb and beef adipose tissue were too low to measure. The mean P:S ratios for beef, lamb and pork muscle were (adipose tissue values in parentheses): 0.11 (0.05); 0.15 (0.09) and 0.58 (0.61), and the n−6:n−3 ratios were 2.1 (2.3), 1.3 (1.4) and 7.2 (7.6). We conclude that the muscles of red meat species are a valuable source of PUFA, particularly the C20 and C22 n−3 fatty acids, in the human diet and that, considered as part of a varied diet, the low P:S ratio of the ruminant muscle, the high n−6:n−3 ratio of pork and the total fatty acid contents do not detract significantly from the nutritional value of lean meat.     

The effect of ionising radiation on the colour of beef, pork and lamb

The effect of irradiation (0 and 5 kGy) of beef, pork and lamb portions in retail overwrap packs and subsequent storage at 4°C was studied in relation to colour changes. The colour of the exterior surface of beef and pork was measured on the same samples on each day of storage for up to 7 days post irradiation. On day 7 the colour of a freshly cut surface was measured. The colour of both the exterior and a freshly cut surface of lamb, in similar retail overwrap packs was measured at 2, 5 and 7 days, post irradiation, different samples being used on each day of measurement. L* values of irradiated beef increased significantly with storage and a* values for unirradiated samples decreased significantly with storage. For lamb there was a general increase in L* and h(o) values and a decrease in a*, b* and C* values with storage. Analyses of the day 7 data showed statistically significant effects for species on all CIELAB parameters. Irradiation resulted in significantly higher hue angle (h(o)) values and the a*, b* and C* values were significantly higher on the exterior than freshly cut surface. There were a number of statistically significant 2 factor and 3 factor interactions. The role of formation of a carboxyhaem pigment in the colour of irradiated meat is discussed. The problem of interpretation of pigment changes from CIELAB values is highlighted.     

Tenderising in M. longissimus dorsi of beef, veal, rabbit, lamb and pork

The decrease in toughness of M. longissimus dorsi with storage time at 1°C was effectively described by an exponential decay equation. The average rate constant for beef, veal and rabbit was 0·17 whilst that for lamb was 0·21 and that for pork, 0·40 days(-1). However, the rate constants were not significantly different due to variations both within muscles and between animals. On average, 50% of the tenderising occurred in 2 days for pork and in 4·2 days for beef, veal and rabbit, and 80% in 4·9 and 9·5 days, respectively. At the completion of tenderising, beef and rabbit were the toughest and pork the most tender, whilst the greatest tenderising occurred in beef and lamb.     

Comparison of flavor changes in cooked-refrigerated beef, pork and chicken meat patties

Beef and pork longissimus dorsi (LD) and semimembranosus (SM) and chicken breast (B) and thigh (T) muscles excised 24 h postmortem were ground by muscle/species group, formed into patties, pan-fried, refrigerated for 0, 3 or 6 days, and evaluated by a trained sensory panel for intensity of specific flavors. The rate of decline in species-specific natural meat flavor intensity and the rate of increase in "cardboard" (CBD) flavor intensity during the first half of the 6-day storage were fastest for beef, while such decline and increase during the entire storage period were slowest for chicken B. Overall trends of natural meat flavor and CBD intensity changes for chicken T appeared more like those for the red meats than chicken B. It was concluded that, while flavor deterioration can occur in cooked-stored meats from all the species, quantitative or the magnitude of differences between species would depend on muscle types and sensory terms/method used.     

Consumer perception, facts and possibilities to improve acceptability of health and sensory characteristics of pork

Changes at consumer level, as well as an image decline of the meat sector, resulted in considerable decreases of fresh meat consumption. Consumer orientation is considered as a prerequisite to slow down or reverse the adverse fresh pork consumption evolution. Consumer perception of pork is taken as the starting point of this article. Focus is first on assessing differences between facts related to nutritional value and healthiness aspects of pork and their perception by Belgian meat consumers. Second, possibilities of improving pork characteristics are identified. Pork is perceived worst as compared to beef and poultry on the attributes leanness, healthiness, taste and tenderness. Consumer-oriented response strategies should focus at improving these intrinsic quality characteristics, before other elements like traceability, labelling or marketing can be implemented successfully. The possibilities to improve nutritional value, healthiness and sensory characteristics pertain to selection, pig diet composition, transport, slaughter and post-slaughter circumstances. A successful adoption of consumer orientation urges for co-operation throughout the entire pork production chain. The identified topics are key attention points for adequate production and marketing by the pork sector, as well as for consequent communication by government and public services.     

Phenolic acids composition and antioxidant activity of canola extracts in cooked beef,chicken and pork

Crude polyphenol extracts (15 or 100 mg gallic acid equivalents (GAE)/kg meat) from canola meal reduced the formation of 2-thiobarbituric acid-reactive substances (TBARS) in pre-cooked beef (66–92%), pork (43–75%) and chicken (36–70%). The canola extract contained sinapic (99.7%), ferulic (0.28%) and p-hydroxybenzoic acids (0.07%).     

Multiplex real-time PCR for the detection and quantification of DNA from beef, pork, chicken and turkey

Many meat products are composed of two or more meat species. To determine the proportion of these meat fractions, a quantitative multiplex PCR was developed for the quantification of beef, pork, chicken and turkey. This system proved its applicability, precision and accuracy in examining different meat products from the market. Thus it allows the efficient control of composed meat products in official food control and production control laboratories.     

The relationship of bacterial numbers and types to diamine concentration in fresh and aerobically stored beef, pork and lamb

Bacterial numbers and putrescine and cadaverine concentrations were measured in intact beef, pork and lamb and minced beef at retail and during aerobic chill storage at 5°C. Putrescine concentrations increased consistently with 'total' aerobic viable count (TAVC) but cadaverine concentrations increased only when high numbers of presumptive Enterobacteriaceae were present. Significant changes in diamine concentration did not occur until the TAVC exceeded 4.2 × 10⁷/cm² or g when the meat was clearly spoiled. Changes prior to the onset of spoilage were not sufficient for their use as a predictive indicator of the acceptability of the meat.     

Effect of electron-beam irradiation before and after cooking on the chemical properties of beef, pork, and chicken

Ground beef, pork, and chicken thigh meats were irradiated at 0 or 5.0kGy before and after cooking and then stored at -40°C in oxygen permeable bags. The pH, lipid oxidation, volatiles, and carbon monoxide production of the meat were determined at 0 and 6months of storage. The pH values of raw meats from different animal species were different (5.36-6.25) and were significantly increased by cooking, irradiation, and storage (p<0.05). Irradiation had no effect on the TBARS values of ground beef and pork, but significantly increased the TBARS of chicken thigh meat. Cooking, whether it was done before or after irradiation, caused significant increase in TBARS and was most significant in chicken and pork. The numbers of volatiles analyzed by GC/MS were higher in irradiated meats than the non-irradiated ones regardless of meat source. Sulfur-containing compounds were newly produced or increased by irradiation, but dimethyl disulfide and dimethyl trisulfide were not detected in the non-irradiated meats regardless of cooking treatment. Irradiation time, whether done before or after cooking, had little effect on the TBARS, volatiles, and carbon monoxide production in the meat.     

"Chilled" pork - Part II. Consumer perception of sensory quality

The objective of this study was to compare consumer perception of the sensory quality of grilled Canadian pork destined for Japanese and domestic markets, with particular reference to export selection criteria imposed by Japanese importers and transportation conditions. Consumers from Quebec, Canada tasted local and export quality pork subjected to "chilled" (aged 43days at -1.7°C) or conventional ageing (5days at 3.1°C). Consumers' scores (out of 10) were higher (P<0.05) in the "chilled" than conventionally aged pork for tenderness (6.8 vs 5.7), juiciness (6.6 vs 6.0), taste liking (6.4 vs 5.9) and overall acceptability (6.7 vs 6.1). When informed that the conventionally aged, domestic quality pork was destined for the domestic market, consumer scores increased significantly (P<0.05). No effect of information was observed on the perception of the 'chilled' export quality meat, perhaps a consequence of the high sensory quality observed prior to labelling.     

“Chilled” pork — Part II. Consumer perception of sensory quality

The objective of this study was to compare consumer perception of the sensory quality of grilled Canadian pork destined for Japanese and domestic markets, with particular reference to export selection criteria imposed by Japanese importers and transportation conditions. Consumers from Quebec, Canada tasted local and export quality pork subjected to “chilled” (aged 43 days at − 1.7 °C) or conventional ageing (5 days at 3.1 °C). Consumers' scores (out of 10) were higher (P < 0.05) in the “chilled” than conventionally aged pork for tenderness (6.8 vs 5.7), juiciness (6.6 vs 6.0), taste liking (6.4 vs 5.9) and overall acceptability (6.7 vs 6.1). When informed that the conventionally aged, domestic quality pork was destined for the domestic market, consumer scores increased significantly (P < 0.05). No effect of information was observed on the perception of the ‘chilled’ export quality meat, perhaps a consequence of the high sensory quality observed prior to labelling.     

The effect of freezing and thawing on the magnetic resonance imaging parameters of water in beef, lamb and pork meat

A new multisample magnetic resonance imaging (MRI) technique has been used to measure the values of T ₁, T ₂, magnetization transfer (MT) rate and liquid proton density ratio ( M ₀%) for water in fresh and frozen–thawed beef, lamb and pork; four samples from the longissimus dorsi muscle of 25 different individuals per species were studied. The effect of two different chilling regimes, standard and tenderloin, were also studied. Standard chilled pork and lamb had a significantly higher M ₀% than tenderloin chilled samples, but there was no correlation between M ₀% and fresh weight; the differences in M ₀% are thought to be due to differences in MR (magnetic resonance)-visible water. There was a significant decrease in water content, T ₁ relaxation time, and a significant increase in MT rate in the frozen–thawed samples when all the data were pooled for each species. However, individual animals differed in the magnitude and direction of the change; this means that because of interanimal variation, measurements of MR parameters from a single sample of meat cannot be used at present to authenticate it.     

种属特异性PCR法鉴别罐头食品中猪、牛、羊、鸡、鸭源性成分

建立适用于肉类罐头等长时间高温加工食品中猪、牛、羊、鸡、鸭5种动物源成分种属特异性PCR鉴别方法。通过使用猪、牛、羊、鸡、鸭的种属特异性引物,对5种动物的总DNA模板进行PCR扩增,得到分别为212、147、202、131、201 bp的扩增产物,将测序结果在美国国家生物技术信息中心(US National Center for Biotechnology Information,NCBI)进行BLAST比对确认实验的准确性,并对市售罐头样品进行检测。该方法 5种动物引物种属特异性良好,对猪、牛、羊、鸭源性成分的检测灵敏度可达1%,对鸡源性成分的检测灵敏度为2.5%。在对市售肉类罐头样品的检测中,6.6%样品与标签标注结果不符。该方法操作简便,成本低,结果准确可靠,可广泛用于肉类罐头食品和长时间高温加工食品中猪、牛、羊、鸡、鸭5种动物源成分的鉴别,具有十分广泛的实际应用价值。