Growth ofListeria monocytogeneson sliced cooked meat products

During the shelf life (4–6 weeks) of artificially contaminated sliced cooked meat products such as luncheon meat, ham and chicken breast, the growth ofListeria monocytogenesunder vacuum was similar to the growth under modified atmosphere (30% CO₂/70% N₂) packaged products. The presence of competitors (lactobacilli), even in concentrations 100 times those ofL. monocytogenes, only slightly inhibited growth of this pathogen. At the end of the shelf life levels were still 10⁷cfug⁻¹. Due to the lower initial contamination, levels in naturally contaminated products were about 10⁴cfug⁻¹. To prevent outgrowth ofL. monocytogenesto such high levels it is necessary to prevent recontamination during slicing and packaging, and to shorten the rather long shelf life of these products. Due to the low pH of fermented sausage (saveloy) and (raw) Coburger ham the numbers ofL. monocytogenesdecreased below the detection level.     

Occurrence of heterocyclic amines in cooked meat products

Heterocyclic amines (HCAs), potent mutagens and a risk factor for human cancers, are produced in meats cooked at high temperature. The aim of this study was to determine the HCA content in cooked meat products (beef, chicken, pork, fish) prepared by various cooking methods (pan frying, oven broiling, and oven baking at 170 to 230 °C) that are preferred by U.S. meat consumers. The primary HCAs in these samples were PhIP (2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine) (1.49-10.89 ng/g), MeIQx (2-amino-3,8-dimethylimidazo [4,5-f]quinoxaline) (not detected-4.0 ng/g), and DiMeIQx (2-amino-3,4,8-trimethyl-imidazo [4,5-f]quinoxaline) (not detected-3.57 ng/g). Type and content of HCAs in cooked meat samples were highly dependent on cooking conditions. The total HCA content in well-done meat was 3.5 times higher than that of medium-rare meat. Fried pork (13.91 ng/g) had higher levels of total HCAs than fried beef (8.92 ng/g) and fried chicken (7.00 ng/g). Among the samples, fried bacon contained the highest total HCA content (17.59 ng/g).     

Creatinine,creatine and protein in cooked meat products

The accuracy of the results obtained with a flow injection (FI) system for the simultaneous determination of creatinine and creatine in cooked meat products was evaluated in 30 samples by comparison with those obtained by reference methods. The FI method was then applied to 52 different samples (cooked ham, 14; frankfurters, 11; wieners, 9; chopped, 10; mortadella, 8) and the protein content was also determined. From % creatinine of total creatine (creatine + 1.159 creatinine) an estimation of the heat treatment applied in the processing was made. Cooked ham, mortadella and chopped had the highest values, indicating that the cooking conditions were more severe for these products than those used in the sausages. The ratio of total creatine/protein permitted an estimation of muscular protein to be made. According to the mean value for this ratio, the products were ordered as: cooked ham, 21.9 > chopped, 17.7 > wieners, 15.9 > mortadella, 13.0 > frankfurters, 12.3mg total creatine per gram of protein.     

如何保证熟肉制品杀菌彻底

熟肉制品以其品种多样、食用方便深受消费者的青睐.但是夏季熟肉制品的胀袋、变质现象,是制约肉制品企业发展的一个瓶颈.而导致产品出现胀袋、变质现象的主要原因为产品杀菌不彻底.     

散装熟肉制品中单增李斯特菌污染状况分析

目的分析散装熟肉制品中单增李斯特菌污染状况。方法根据GB 4789.30-2016《单核细胞增生李斯特氏菌检验》规定的方法对散装熟肉制品的加工用原料、生产环境、各加工环节中产品以及不同销售环境下产品中的单增李斯特菌进行定性和定量检测。结果原料肉的总体带菌率达到21%;生产环境中第三区(远离食品接触面的区域)检出率为2%,其余区域未检出;各加工环节中产品单增李斯特菌检测结果均小于10CFU/g;不同销售环境下产品中单增李斯特菌检测结果小于10 CFU/g的比例为93%,处于10～50 CFU/g之间的样本占比6%,大于50 CFU/g的占比为1%。结论原料散装熟肉制品中单增李斯特菌污染的主要来源,蒸煮等加工环节能有效地杀灭单增李斯特菌。销售环境也关系到散装熟肉制品单增李斯特菌的污染程度,对于未包装的产品,专卖店优于农产品市场。     

市售熟肉制品氧化安全性分析

通过测定和分析市售火腿肠、肉片和肉松3类熟肉制品的氧化产物丙二醛穴MDA雪和亚硝酸钠盐穴NO2雪这两种致癌物质,对市售肉制品的安全性进行了分析和评估。13个产品中,只有一个鸡肉卷火腿肠的NO2残留量超标穴36mg/kg雪,其余肉制品的NO2含量均在允许范围。火腿肠类的MDA值低于0.5mg/kg熏未出现异味,说明其是安全的,但是脂肪和蛋白质含量普遍偏低,影响了口感和应有的品质。肉干及肉松类的MDA值均超过0.5mg/kg,已出现热异味(WOF),具有潜在的安全危害,应引起重视。     

Growth of and toxin production by Aeromonas hydrophila and Aeromonas sobria at low temperatures

The effects of different temperatures on the growth and toxin production of Aeromonas hydrophila and Aeromonas sobria were studied. The results showed that these Aeromonas species are not only able to grow at low temperatures (e.g. at 4 and 10 degrees C) but may also produce cytotoxin, hemolysin and enterotoxin under suitable growth conditions.     

Experimental evidence for toxin production by Aeromonas hydrophila and Aeromonas sobria in a meat extract at low temperatures

The ability of enterotoxigenic strains of Aeromonas hydrophila and Aeromonas sobria to produce exotoxins (enterotoxin and haemolysin) in a meat extract at low temperatures (5 and 12 degrees C) was investigated. All three strains incubated at 12 degrees C were enterotoxigenic and haemolytic in the meat extract after 5 days. At 5 degrees C, five of the six strains tested were able to produce these exotoxins after 8 days incubation while one strain was neither enterotoxigenic nor haemolytic after 5, 8 and 11 days. The possible involvement of performed toxin(s) in Aeromonas gastroenteritis is also discussed.     

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.     

Growth kinetics and predictive model of Aeromonas hydrophila in a broth-based system

This study developed a predictive model of Aermonas hydrophila in tryptic soy broth for any combination of temperatures (5 to 40°C), pH (6 to 8), and NaCl (0 to 5%) using a response surface model. A. hydrophila tended to grow within a pH range of 6.0 to 8.0 and could not tolerate NaCl up to 5.0%. The interaction of pH and NaCl did not affect the specific growth rates (SGR). The primary model to obtain the SGR showed a good fit (R²≥0.980). A secondary model was obtained by non-linear regression analysis and calculated as: SGR= 0.4577+0.0529X₁−0.1641X₂−0.1493X₃−0.0016X₁X₂−0.0001X₁X₃+0.0115X₂X₃0.0006X₁ ²+0.0114X₂ ²+0.0150X₃ ² (X₁=temperature, X₂=pH, X₃=NaCl). The appropriateness of the polynomial model was verified by the mean square error (0.0023), bias factor (0.922), accuracy factor (1.343), and coefficient of determination (0.937). The newly secondary model of SGR for A. hydrophila could be incorporated into the tertiary model to predict the growth of A. hydrophila.     

Growth of Aeromonas hydrophila K144 as Affected by Organic Acids

The influence of different acids on the aerobic growth kinetics of Aeromonas hydrophila was studied in BHI broth with 0.5 and 2.0% NaCl incubated at 5 and 19°C. Growth curve data were analyzed by the Gompertz equation and a nonlinear regression program; generation and lag times were calculated from the Gompertz parameters. Type of acid, pH, NaCl level and temperature influenced lag and generation times. The organic acids (acetic, lactic, citric and tartaric) inhibited growth at higher pH values than inorganic acids (HCl and H₂SO₄). The high NaCl level interacted with type of acid and pH to restrict growth of the organism at the lower temperature of incubation. Acetic and lactic acids were effective in controlling the growth of A. hydrophila and could readily be combined with low holding temperature to render foods free of the organism.     

影响熟肉制品辐照所致脂肪氧化因素分析

就辐照诱导熟肉制品脂肪氧化机理进行了阐述,并分析不同因素(如脂肪含量、辐照剂量、包装形式、贮藏温度、添加剂、贮藏时间等)对辐照熟肉制品脂肪氧化的影响。     

辽宁省熟肉制品中氯霉素残留检测结果分析

目的 了解2011年辽宁省餐饮业熟肉制品中氯霉素残留状况,为监管部门提供科学的理论数据.方法 采用多阶段分层随机抽样的方法在辽宁省五个城市中抽取熟肉制品162份.按照检测标准要求采用液相色谱-串联质谱法,以间位氯霉素为内标物进行测定.检出率的比较采用x2检验分析,P ＜0.05为差异有统计学意义.结果 162批样品中,有40批检测出氯霉素残留,检出率为24.7％.不同城市和不同品种间检出率存在统计学差异.结论 辽宁省熟食制品中氯霉素残留情况比较严重,应该引起监管部门的关注.     

甘肃省居民对市售熟肉制品中亚硝酸盐的暴露评估

目的了解甘肃省市售熟肉制品中亚硝酸盐的含量,并对造成的人群健康风险进行评估。方法采用非连续3 d 24 h回顾方法入户调查1 466名居民的肉类食物消费状况,并结合363份市售熟肉制品中亚硝酸盐含量检测数据,采用简单分布的方法获得人群熟肉制品亚硝酸盐每日暴露量,并与亚硝酸盐的每日允许摄入量进行比较,评估甘肃省居民熟肉制品亚硝酸盐暴露风险。结果甘肃省市售熟肉制品中亚硝酸盐检出率为85.40%(310/363),超标率为3.31%(12/363),平均含量为7.76 mg/kg。甘肃省居民熟肉制品中亚硝酸盐每日平均暴露量为0.002 3 mg/kg BW,高端消费人群暴露量(P97.5)为0.008 3 mg/kg BW,为每日允许摄入量的11.86%。结论甘肃省居民通过熟肉制品摄入的亚硝酸盐所致的健康风险较低,但仍需对市售熟肉制品中亚硝酸盐的规范使用加强监督。     

东莞市区肉菜市场熟肉制品中金黄色葡萄球菌污染溯源分析

目的优化熟肉制品中金黄色葡萄球菌的快速污染溯源分析方法。方法对熟肉制品及其加工环境进行采样,应用3MPerifilmTM金黄色葡萄球菌快速测试片对样品定量检测,对分离出的阳性菌株运用全自动微生物基因指纹鉴定系统RiboPrinter,结合EcoRI酶,对其进行分子溯源。结果 168个样品中分离出的7株菌共分为2种核糖体基因型,其中6株为同一核糖体条带类型,显示来源于相同克隆株。结论该方法全程只需3 d时间,快速稳定,可满足监管快速检测鉴定、分型溯源的要求。RiboPrinter的优势在于快速溯源,进行种的鉴定时应结合其他手段来进行确认。     

Effect of High Hydrostatic Pressure on Aeromonas hydrophila AH 191 Growth in Milk

Abstract: Exposure to high pressure is an efficient method of bacterial inactivation that is particularly important for reducing the microbial load present in foods. In this study, we examined the high pressure inactivation of Aeromonas hydrophila AH 191, a virulent strain that produces aerolysin, a cytotoxic, enterotoxic, and hemolytic toxin. High pressure treatment (250 MPa for 30 min at 25 °C in 0.1 M PBS, pH 7.4) of A. hydrophila grown in milk reduced bacterial viability by at least 9 orders of magnitude. Under these conditions, the enterotoxic, hemolytic, and cytotoxic activities of A. hydrophila culture supernatants were unaltered. These results indicate the need for caution in the use of high pressure for food processing since although truly toxigenic bacteria may be inactivated, their toxins may not be, thus posing a risk to human health. At higher pressure (350 MPa) the inactivation of bacteria was much more effective. Scanning electron microscopy showed a significant decrease in the number of bacteria after higher pressurization (350 MPa for 1 h) and transmission electron microscopy showed irregular shaped bacteria, suggestive of important cell wall and membrane damage, and cytoplasm condensation. Practical Application: High pressure inactivates Aeromonas hydrophila efficiently but is enhanced when combined with moderate temperature (40 °C). The biological activities of toxins from this bacterium are unaltered under these conditions.     

Assessment of mathematical models for predicting Staphylococcus aureus growth in cooked meat products

The growth of Staphylococcus aureus in commercially available vacuum-packaged cooked ham, turkey breast meat, and chicken breast meat stored at 2.3, 6.5, 10, 13.5, and 17.7 degrees C was studied. Growth rates observed in these food products were compared with those predicted on the basis of various growth models found in the literature and with those generated by the Pathogen Modeling Program and the Food MicroModel software using graphical and mathematical analysis for performance evaluation. In general, the models studied overestimated the growth of S. aureus. The Dengremont and Membré model most closely matched the observed behavior of S. aureus in ham and chicken breast meat, with bias factors of 1.56 and 1.09, respectively. The Eifert et al. model accurately described the growth of S. aureus in turkey breast meat, with a bias factor of 1.51. The remaining models provided safe predictions of the growth rate of S. aureus, but with poor accuracy. Predictive microbiology models have an immediate practical application in improving microbial food safety and quality and are very useful decision support tools, but they should not be used as the sole determinant of product safety.     

高效液相色谱法测定熟肉制品中的刚果红

目的建立高效液相色谱测定熟肉制品中刚果红的检测方法。方法样品经石油醚去除脂肪,以氨水-乙醇(20:80,体积比)溶液提取,乙酸调节p H至中性,以水定容、离心。经ZORBAX SB-Aq色谱柱(4.6 mm×250mm,5μm)分离,甲醇-20 mmol/L乙酸铵为流动相,梯度洗脱,检测波长500 nm,外标法定量。结果刚果红在0.1~10μg/m L浓度范围内线性关系良好,相关系数大于0.999,添加回收率在82.5%~90.7%之间,相对标准偏差为在2.26%~7.29%之间,方法检出限为0.02 mg/kg。结论该方法简便、快捷,回收率和重现性好,适用于熟肉制品中刚果红的测定。     

ELISA-test for cooked meat species identification on gelatine and gelatine products

The results of the ELISA-test with a commercial cooked meat species identification kit on gelatine and gelatine containing products can be influenced by different gelatine types and concentrations leading to false positive readings. The test cannot be applied especially to meat products containing relatively high amounts of soluble collagens because their extracts form solid gels in the test wells. In this case the different reagents added will penetrate the gels and react with each other. The kit may not speciate reliablely commercial gelatine in isolation or in products where gelatine is the sole animal protein source.     

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.