Addition of tea catechins and vitamin C on sensory evaluation, colour and lipid stability during chilled storage in cooked or raw beef and chicken patties

The effects of addition of tea catechins (TC) and vitamin C (VC) on sensory evaluation, colour and lipid stability in cooked or raw beef and chicken meat patties during refrigerated storage were studied. Fresh beef striploin and chicken breast muscles were minced, following removal of external fat and connective tissue. Following mincing, beef and chicken were assigned to one of the following five treatments: control (meat treated with no antioxidant); TC200, meat plus 200 mg TC/kg muscle; TC400, meat plus 400 mg TC/kg muscle; VC200, meat plus 200 mg VC/kg muscle, VC400, meat plus 400 mg VC/kg muscle. Sodium chloride (1%) was added to all samples. Patties (125 g portions), formed from the above-treated minced meat, were oven cooked, cooled, and packaged in 30% CO₂:70% N₂. Fresh raw beef and chicken patties were packaged in 80% O₂:20% CO₂. All samples were stored for up to 7 days under fluorescent lighting at 4 °C. Sensory parameters (colour, flavour, taste, tenderness and overall acceptability) were evaluated on cooked beef and chicken patties after 1, 3 and 6 days of storage. Surface colour (Hunter L, a and b values), and lipid oxidation (2-thiobarbituric acid reactive substances) were measured on days 1, 3 and 6 of storage for cooked meats and on days 2 and 7 for raw beef and chicken. Tea catechins addition (200 or 400 mg/kg) to minced meat caused (P < 0.05) discolouration in cooked beef and chicken meat patties and significantly reduced (P < 0.001) lipid oxidation in cooked or raw beef patties compared to the control. Beef, either raw or cooked, was more susceptible (P < 0.01) to oxidation compared to chicken. Raw meat stored in high oxygen conditions was more susceptible to lipid oxidation than cooked meat stored in anaerobic conditions. Tea catechins treatments (TC200 and TC400) inhibited (P < 0.05) lipid oxidation in raw beef to a greater extent than vitamin C treatments (VC200 and VC400). These results indicate that tea catechins are potent natural antioxidants and exhibit greater antioxidant efficacy compared to vitamin C.     

Effect of phosvitin on lipid and protein oxidation in ground beef treated with high hydrostatic pressure

In this study, we aimed to examine the effect of phosvitin on lipid and protein oxidation of raw and cooked ground beef treated with high hydrostatic pressure (HHP). Ground beef patty with 0, 500, or 1000 mg phosvitin/kg meat was treated with HHP at 0.1, 300, or 600 MPa. Half of the patties were used in a raw meat analysis, and the other half were used in a cooked meat analysis. Phosvitin and HHP treatment at 300 MPa synergistically reduced microbial growth, and HHP treatment at 600 MPa reduced microbial counts to undetectable levels (< 1 log CFU/g) throughout the length of the study in all samples. Phosvitin delayed lipid and protein oxidation in HHP-treated cooked and raw ground beef, respectively. However, phosvitin had no effect on the color changes of raw ground beef attributable to HHP. The results indicated that phosvitin could enhance the stability of lipids and proteins but not color changes of raw ground beef caused by HHP.     

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.     

Effect of Heat Treatment on Bioavailability of Meat and Hemoglobin Iron Fed to Anemic Rats

Efficiency of converting dietary iron from meat, bovine hemoglobin (HB) and ferrous sulfate into hemoglobin was investigated in anemic rats. Raw or autoclaved HB, and raw, autoclaved, boiled, or baked beef round, and ferrous sulfate were mixed into diets to give 36 mg Fe/kg diet. Heat treatments increased the efficiency of converting both HB and meat iron into hemoglobin by the anemic rats. Efficiencies of conversion were 23, 30, 33, 37, 37, 36 or 60 (LSD 0.05/0.01 = 4/6), respectively, for raw HB, autoclaved HB, raw meat, autoclaved meat, boiled meat, baked meat or ferrous sulfate. An in vitro measurement of iron availability in meat correlated poorly with bioavailability determined in rats. Cooking did not significantly affect the bioavailability of meat iron.     

酶联免疫吸附法快速测定不同样品 基质中三聚氰胺

目的 探求不同样品基质中三聚氰胺残留量的快速检测方法.为快速筛查不同种类食品中非法添加三聚氰胺提供技术保障.方法 采用酶联免疫吸附法在奶制品(奶粉、液态奶)、成品饲料(鸡饲料、猪饲料)、饲料原料(鱼粉、肉骨粉、豆粕、麸皮)、肉类(鸡肉、猪肉、内脏)等样品基质中添加一定浓度的三聚氰胺进行测定,并对检测结果进行分析.结果 酶联免疫试剂盒对奶制品和肉类检出限均能达到1.0 mg/kg;对成品饲料基质中的三聚氰胺的检测,检出限可达到2 mg/kg,而对饲料原料中的三聚氰胺的检测,检出限都不能达到2 mg/kg.结论 对奶制品中的三聚氰胺检测完全符合我国的临时限量标准;对成品饲料中的三聚氰胺残留的检测同样符合其限量标准(2.5 mg/kg),而对饲料原料中的三聚氰胺的检测,由于不同基质中检出限不同,不能直接采用酶联免疫法进行快速筛查;酶联免疫法也适用于肉类中的三聚氰胺的检测.     

Cholesterol oxidation in frozen dark chicken meat: influence of dietary fat source, and α-tocopherol and ascorbic acid supplementation

A factorial design assessed the effect of dietary fat source (beef tallow, fresh and oxidized sunflower oils, and linseed oil), and α-tocopheryl acetate (α-TA) and ascorbic acid (AA) supplementation (225 and 110 mg/kg feed, respectively) on the cholesterol oxidation product (COP) content and 2-thiobarbituric acid (TBA) values in raw and cooked dark chicken meat vacuum packaged and stored at -20°C for 7 months. COP determination showed good linearity, recovery and precision. Dietary α-TA was highly effective in protecting raw or cooked meat from cholesterol and fatty acid oxidation, regardless of its degree of unsaturation. In contrast, AA supplementation was ineffective and even promoted oxidation in raw meat from broilers fed unsaturated fat diets that had not been supplemented with α-TA. Oxidation values (raw or cooked meat) from α-TA or α-TA+AA supplemented diets were not statistically different (P>0.05). TBA and COP values were significantly correlated in raw samples (r=0.6466, P=0.0001).     

Combined effects of NaCl and raw meat pH on water-holding in cooked sausage with and without added phosphate

The intake of sodium in diets is of concern in many industrialized countries. Attempts have been made to lower sodium intake via meat products. The keeping quality, taste and water-holding/firmness of meat products have usually been impaired. The water-holding in cooked sausage was determined by a laboratory sausage method. Beef and pork with varying natural post-rigor pH-values (range: pork 5.50-6.12 and beef 5.60-6.48) were used as mixtures, and 0.5-2.5 % NaCl was used with or without added commercial sausage phosphate (2,5 g/kg determined as P(2)O(5)). The pH-values of raw batter increased to a level 0.0-0.7 units higher than the pH-values of the respective meat mixtures. The increase was higher in lower pH-values, with higher salt levels and with added phosphate. The cooking caused an additional increase of about 0.0-0.2 units, and the increase was again higher at lower pH-values. Maximum in water-holding was reached in 2.5% NaCl in all pH-values, both with and without added phosphate. The pH-value of meat raw materials for the maximum water-holding was ca. 6.3. The combined effect of salt and pH is important in high salt contents and low pH-values. By 2.5% NaCl , where the maximum in water-holding was obtained, raw meat pH has the largest effect, but in low NaCl contents, below 1.0%, only a minor effect in pH-values below 5.9, and above that, almost no effect. Approximately the same water-holding as with 2.5% NaCl in pH 5.7 can be reached with 1.5% NaCl in pH 6.1 and above. The effects of the variables were similar with pork and beef. It was concluded that when lowering the salt content in cooked sausages, the pH of the batter should be increased by using high-pH meat mixtures and/or pH-raising phosphates in order to reach a high enough level of water-holding.     

Detection of central nervous system tissue as bovine spongiform encephalopathy specified risk material in traditional Turkish meat products

BACKGROUND: This study used enzyme‐linked immunosorbent assay kits to investigate the presence of central nervous system (CNS) tissue in commercial raw and processed traditional Turkish meat products offered for consumption in various markets. RESULTS: Ninety‐six raw traditional Turkish meat products (32 fresh raw beef patties, 32 cig kofta, 32 pastirma) and 64 processed traditional Turkish meat products (32 doner kebabs and 32 fresh processed beef patties) were analysed. CNS tissue was not found in pastirma, doner kebab, or fresh processed beef patty samples. The levels of CNS contamination in fresh raw beef patties were low (0.1% absorbance standard; 3.1%) and moderate (0.2% absorbance standard; 6.2%). The level of contamination in the cig kofta was low (0.1% absorbance standard; 18.8%). CONCLUSION: CNS tissue was present in all raw traditional Turkish meat products except for pastirma. Copyright © 2011 Society of Chemical Industry     

Comparative evaluation of a phage protein ligand assay with real-time PCR and a reference method for the detection of Escherichia coli O157:H7 in raw ground beef and trimmings

Enterohemorrhagic Escherichia coli O157:H7 is an important pathogen associated with infections caused by consumption of undercooked raw meat. Sensitive and rapid detection methods for E. coli O157:H7 are essential for the meat industry to ensure a safe meat supply. This study was conducted to compare the sensitivity of the VIDAS ultra performance E. coli test (ECPT UP) with a noncommercial real-time (RT) PCR method and the U.S. Department of Agriculture, Food Safety and Inspection Service (USDA-FSIS) reference method for detecting E. coli O157:H7 in raw ground beef. Optimal enrichment times and the efficacy of testing different types of raw meat, either as individual samples (25 g) or as composites (375 g), were examined. For 25-g samples of each type of raw ground beef tested, 6 h of enrichment was sufficient for both the VIDAS ECPT UP and RT-PCR methods, but for 375-g samples, 24 h of enrichment was required. Both the VIDAS ECPT UP and RT-PCR methods produced results similar to those obtained with the USDA-FSIS reference method after 18 to 24 h of enrichment. The primer specificity of the RT-PCR assay and the highly specific phage ligand used in the VIDAS ECPT UP for target recognition enabled the detection of low levels of E. coli O157:H7 in 25 g of various types of raw ground beef. The tests also allowed the detection of E. coli O157:H7 in composite raw ground beef and trimmings in samples of up to 375 g.     

Sandwich ELISA for detection of horse meat in raw meat mixtures using antisera to muscle soluble proteins

A double-antibody sandwich ELISA (enzyme-linked immunosorbent assay) has been successfully developed for the detection of defined amounts of horse meat (1-50%) in unheated meat mixtures. The assay uses horse-specific antibodies obtained by immunoadsorption of the crude horse antisera onto immobilised sarcoplasmic extracts from chicken, beef and pig to remove cross-reacting antibodies. The purified antibodies bound to a solid support sequester horse muscle soluble proteins from meat mixtures. Further immunorecognition was made with the same antibodies conjugated to the enzyme horseradish peroxidase. Subsequent enzymic conversion of substrate gave clear optical density differences when assaying mixtures of minced beef and pig containing variable amounts of horse meat.     

Residues of lead,cadmium, mercury and tin in canned meat products from Egypt: an emphasis on permissible limits and sources of contamination

In an attempt to determine the residual levels of lead (Pb), cadmium (Cd), mercury (Hg) and tin (Sn) in canned meat products marketed in Egypt, a total number of 160 random samples (40 each) of canned chicken luncheon (CCL), canned beef luncheon (CBL), canned frankfurter (CF) and canned corned beef (CCB) were randomly collected from different supermarkets in Egypt to be analyzed using atomic absorption spectrophotometry. From the obtained results, it was found that the mean values of residual levels of Pb in examined CCL, CBL, CF and CCB samples were 0.330, 0.224, 0.206 and 0.334 mg/kg, respectively, while those of Cd were 0.057, 0.053, 0.039 and 0.042 mg/kg, those of Hg were 0.387, 0.450, 0.402 and 0.332 mg/kg, and finally those of Sn were 2.061, 2.308, 0.755 and 1.997 mg/kg. The obtained results were compared with the permissible limits of heavy metals recommended by international and national authorities. In addition, the public health significance as well as the sources of contamination of canned meat products by heavy metals were addressed.     

Detection of chicken meat in raw meat mixtures by a sandwich enzyme immunoassay

A double-antibody sandwich ELISA (enzyme-linked immunosorbent assay) has been successfully developed for the detection of low levels of chicken meat (1–30%) in unheated meat mixtures. The assay uses chicken-specific antibodies, obtained by immunoadsorption of the crude chicken antisera onto immobilized sarcoplasmic extracts from beef, pig and horse, to remove cross-reacting antibodies. The purified antibodies, bound to the wells of a microtitre plate, sequester chicken muscle soluble proteins from saline extracts of meat mixtures. Immuno-recognition is made with similar purified antibodies conjugated to the enzyme horseradish peroxidase. Subsequent enzymic conversion of substrate gives clear optical density differences, when assaying minced beef and pig containing variable amounts of chicken meat.     

Differentiation of raw meat from phylogenically related species by enzyme-linked immunosorbent assay

A method, based on enzyme-linked immunosorbent assay (ELISA), has been developed for differentiating raw meat from closely related species of economic importance. By visual assessment 0·1% donkey in horse, 0·1% goat in sheep and 1% buffalo in beef may be detected. The technique is rapid and simple to perform and could be used in abattoirs and coldstores with results being available within 1 h.     

Detection of recombinant DNA from genetically modified papaya

A method using polymerase chain reaction (PCR) was developed to detect the genetically modified (GM) papaya (55-1 line), of which the mandatory safety assessment has not been finished in Japan because of insufficient data. The papaya intrinsic papain gene was used as an internal control. The results of PCR amplification of the papain gene segment indicated that a commercial silica membrane type kit (QIAGEN DNeasy plant mini) was useful for extraction of DNA from papaya fruit, but not for extraction from canned papaya fruit. On the other hand, a commercial ion-exchange type kit (QIAGEN Genomic-tip) provided enough purified DNA for PCR from canned papaya fruit. Compared with the parental line and other commercial non-GM papayas, the DNA from GM papaya fruit provided specific amplification bands in PCR with five primer pairs (Nos. 2-6) including beta-glucuronidase and neomycin phosphotransferase II gene-specific ones. On the other hand, the primer pairs recognizing these genes showed false-positive results when we used DNAs from canned papaya. Therefore, we recommend that the primer pairs (Nos. 5 and 6) recognizing the sequences derived from two different species of organism should be used in order to detect specifically the GM papaya in canned fruits.     

高湿挤压技术制作松粕复合素肉的工艺研究

利用高湿挤压技术,以松粕、大豆分离蛋白、谷朊粉为原料制备复合组织蛋白。采用中心旋转组合实验设计,建立感官评价(Y)与物料含水率(A)、挤压温度(B)、螺杆转速(C)的相关数学模型,优化制作复合组织蛋白的工艺参数,并利用复合组织蛋白作为原料,对其进行调味研究制作复合素肉。结果表明,高湿挤压的工艺参数为:物料含水率61%、挤压温度152℃、螺杆转速248 r/min。最佳复合素肉配方为:牛肉香膏1.5 g/100 g、食盐1.5 g/100 g、孜然粉0.8 g/100 g、酱油1.0 g/100 g。对复合素肉进行质构剖面分析,结果为硬度50.04 kg、弹性0.995、内聚性0.902、胶粘性45118.383、咀嚼度44.89 kg、回复性0.581,其内部结构上基本与牛肉相似。      

Ascorbate, green tea and grape seed extracts increase the shelf life of low sulphite beef patties

Green tea (GTE) and grape seed (GSE) extracts are proposed as preservatives for increasing the shelf life of low sulphite raw beef patties. The antioxidant and antimicrobial activities of both extracts were compared with ascorbate. Five groups were established for the patties: Control (with no additives), S (100 SO₂), SA (100 SO₂ + 400 sodium ascorbate), ST (100 SO₂ + 300 GTE) and SG (100 SO₂ + 300 GSE) (mg per kg of meat). Patties were stored at 4 °C in aerobic packaging for 0, 3, 6 or 9 days under retail display conditions. Meat spoilage (total viable and coliform counts, pH, lightness, chroma, hue angle, metmyoglobin and TBARS) was determined. The sensory contribution of the extracts to cooked patties was evaluated (colour, odour, flavour and texture). The results pointed to the possibility of using low SO₂-vegetable extract combinations to preserve raw meat products. ST, SG and SA delayed microbial spoilage, redness loss and lipid oxidation, thus increasing the shelf life of the raw sulphite beef patties by 3 days. ST, SG and SA also delayed the onset of rancid flavours in cooked patties. No anomalous sensory traits were caused by either extract. Ascorbate, GTE and GSE improved the preservative effects of SO₂ on beef patties, especially against meat oxidation. This suggested that the quantity of SO₂ added can be reduced to obtain healthier raw meat products.     

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.     

牛肉酶解工艺及其产物的研究进展

常用于水解牛肉的酶有木瓜蛋白酶、动物蛋白水解复合酶、风味复合酶等,本文总结了蛋白酶水解牛肉的工艺以及酶法水解牛肉的研究现状,归纳了牛肉酶解的3种工艺方法:单酶水解、多酶复合水解和多酶分步水解。结果表明:牛肉经过酶解释放出氨基酸或形成多肽,更利于人体消化吸收,并且具有一定的生物活性,牛肉酶解工艺在肉制品行业中有广阔的发展前景。     

用Dot—ELISA方法检测生肉中的沙门菌

目的 检测生肉中的沙门菌带菌情况,为预防沙门菌食物中毒提供理论参数.方法 应用Dot-ELISA法对西宁市某屠宰厂85份猪胴体,101份羊胴体和71份牛胴体进行沙门菌的检测,同时用常规分离培养鉴定技术作为对照试验.结果 Dot-ELISA法检出沙门菌阳性率分别为76.47％( 65/85),55.44％ (56/101)和46.48％(33/71);而常规分离培养鉴定技术检出沙门菌阳性率分别为78.82％( 67/85)、47.52％ (48/101)和43.66％(31/71).两种方法的阳性符合率分别为86.57％、85.71％和81.82％,两种方法在检测中的差异无显著性(P＞0.05).结论 Dot-ELISA法检测沙门菌快速、准确,且与分离培养法阳性符合率较高;生肉中沙门菌带菌现象较为严重,存在一定的食品安全隐患.     

Occurrence and survival of verocytotoxin-producing Escherichia coli O157 in meats obtained from retail outlets in The Netherlands.

In 1996 and 1997, 2,941 fresh and processed meat products obtained from supermarkets and butcher shops in The Netherlands were examined for the presence of verocytotoxin-producing Escherichia coli of serogroup O157 (O157 VTEC). Additionally, the fate of O157 VTEC in raw meat products stored at low temperatures and the effect of different additives were evaluated. O157 VTEC strains were isolated from 6 (1.1%) of 571 samples of raw minced beef, 2 (0.5%) of 402 samples of raw minced mixed beef and pork, 1 (1.3%) of 76 samples of raw minced pork, 1 (0.3%) of 393 samples of other raw pork products, and 1 (0.3%) of 328 samples of cooked or fermented ready-to-eat meats. Other raw beef products (n = 223) and meat samples originating from poultry (n = 819), sheep or lamb (n = 46), or wild animals (n = 83) were all found to be negative for O157 VTEC. For the survival experiments we used tartaar (minced beef with a fat content of less than 10%) and filet americain (tartaar mixed with a mayonnaise-based sauce [80 to 20%]). The O157 VTEC strain tested was able to survive in tartaar and filet americain stored at -20, 0, 5, or 7 degrees C for 3 days. At both 7 and at 15 degrees C, O157 VTEC counts in tartaar and filet americain remained virtually unchanged throughout a storage period of 5 days. Addition of acetic acid (to pH 4.0), sodium lactate (1 and 2% [wt/wt]), or components of the lactoperoxidase-thiocyanate-hydrogen peroxide system to filet americain did not result in a reduction of viable O157 VTEC cells during storage at 7 or 15 degrees C. It was concluded that raw meat contaminated with O157 VTEC will remain a hazard even if the meat is held at low or freezing temperatures.