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.     

Differentiation between fresh beef and thawed frozen beef

In order to prevent meat retailers offering thawed, imported frozen beef as fresh domestic beef, the method of Gottesmann and Hamm for differentiating between fresh and frozen/thawed meat is recommended. The principle of this method is based on the fact that freezing and thawing of meat results in a release of the enzyme β-hydroxyacyl CoA-dehydrogenase (HADH) from the mitochondrion into the sarcoplasm; an elevated HADH activity in the muscle press-juice indicates freezing and thawing of tissue. The HADH colour test of Gottesmann and Hamm was modified by replacing the electron-transmitter meldolablue by resazurin which results in a much higher colour stability after reaction with fresh meat extracts.     

生鲜肉制品沙门氏菌分离鉴定过程中的

目的 对不同种类的生鲜肉制品进行沙门氏菌检验, 了解沙门氏菌分离鉴定过程中出现的干扰菌种类和特性。方法 对25份生鲜肉制品进行沙门氏菌的分离鉴定, 通过生化试验和全自动微生物鉴定分析系统对出现的可疑菌进行鉴定。结果 在分离鉴定过程中, 干扰菌同沙门氏菌初步生化试验结果相似, 可疑率为79.5%; 鉴定出的干扰菌有奇异变形杆菌、弗氏柠檬酸杆菌、拉氏普罗威登斯菌、温和气单胞菌、嗜水气单胞菌、铜绿假单胞菌、海藻希瓦菌。结论 沙门氏菌分离鉴定过程中存在大量无法通过初步生化排除的干扰菌, 可结合ONPG试验及O多价血清试验进行排除; 鉴定出的干扰菌均为条件致病菌, 需引起重视, 开展其致病性研究。     

Incidence of enterohemorrhagic Escherichia coli, Escherichia coli O157, Salmonella, and Listeria monocytogenes in retail fresh ground beef, sprouts, and mushrooms

The objective of this study was to determine the prevalence of enterohemorrhagic Escherichia coli (EHEC), E. coli O157, Salmonella, and Listeria monocytogenes in retail food samples from Seattle, Wash. A total of 2,050 samples of ground beef (1,750 samples), mushrooms (100 samples), and sprouts (200 samples) were collected over a 12-month period and analyzed for the presence of these pathogens. PCR assays, followed by culture confirmation were used to determine the presence or absence of each organism. Of the 1,750 ground beef samples analyzed, 61 (3.5%) were positive for EHEC, and 20 (1.1%) of these were positive for E. coli O157. Salmonella was present in 67 (3.8%) of the 1,750 ground beef samples. Of 512 ground beef samples analyzed, 18 (3.5%) were positive for L. monocytogenes. EHEC was found in 12 (6.0%) of the 200 sprout samples, and 3 (1.5%) of these yielded E. coli O157. Of the 200 total sprout samples, 14 (7.0%) were positive for Salmonella and none were positive for L. monocytogenes. Among the 100 mushroom samples, 4 (4.0%) were positive for EHEC but none of these 4 samples were positive for E. coli O157. Salmonella was detected in 5 (5.0%) of the mushroom samples, and L. monocytogenes was found in 1 (1.0%) of the samples.     

A risk characterization model of Salmonella Typhimurium in Irish fresh pork sausages

A second-order simulation model was built to estimate the risk of Salmonella Typhimurium associated with the consumption of Irish fresh pork sausages. To select appropriate hazard characterization models, an initial appraisal of the current dose-response models was conducted. The cooking modality of grilling was associated with a higher mean risk of infection per serving (1.399 × 10^? 6; 95% CI: 7.54 × 10^? 7–2.65 × 10^? 6) than frying (6.246 × 10^? 7, 95% CI: 2.78 × 10^? 7–1.17 × 10^? 6). When the risk was extrapolated over the consumption in a year period, the mean risk of infection increased considerably to 8.541 × 10^? 5 with an expected number of infections and illnesses of 184.3 (95% CI: 26–664) and 17 (95% CI: 2–63), respectively. Results highlighted the importance of consumer education, as scenario analysis predicted that, for the current level of Salmonella in pork sausage, decreasing the product's cold storage by approximately 8 h and cooking for an additional half minute can reduce the current risk level by ～ 50%.     

生鲜牛肉调理配制方法对高氧MAP保鲜包装产品保鲜效果的影响研究

以超市新鲜牛肉为原料,以食盐、复合香辛料、料酒添加量作为正交实验因素,研究生鲜调理牛肉在MAP包装下的微生物、色差和pH的变化。实验结果表明,经过调理的生鲜牛肉样品结合高氧MAP包装,在4℃储藏条件下最优组样品第6d产品菌落总数为4.933lgCFU/mL,pH5.76,a*值12.23,符合国家二级生鲜牛肉标准。以菌落总数为目标值进行回归方程优化并试验验证得到最优调理配方为:食盐添加量0.9%、料酒添加量2.0%、香辛料添加量0.6%。      

生鲜牛肉调理配制方法对高氧MAP保鲜包装产品保鲜效果的影响研究

以超市新鲜牛肉为原料,以食盐、复合香辛料、料酒添加量作为正交实验因素,研究生鲜调理牛内在MAP包装下的微生物、色差和pH的变化.实验结果表明,经过调理的生鲜牛肉样品结合高氧MAP包装,在4℃储藏条件下最优组样品第6d产品菌落总数为4.9331g CFU/mL,pH5.76,a值12.23,符合国家二级生鲜牛肉标准.以菌落总数为目标值进行回归方程优化并试验验证得到最优调理配方为:食盐添加量0.9％、料酒添加量2.0％、香辛料添加量0.6％.     

猪肉及其制品中非伤寒沙门菌定量风险评估研究进展

非伤寒沙门菌是全球重要的食源性致病菌之一,主要通过污染的畜禽食品感染人类。本文综述了国外猪肉及其制品中非伤寒沙门菌定量风险评估研究现状,重点解析常用模型,并分析我国猪肉中非伤寒沙门菌定量风险评估目前存在的挑战,以期为进一步开展相关风险评估提供参考依据。     

热反应牛肉粉、牛肉膏及其在西式肉制品中的应用

介绍热反应牛肉粉、牛肉青的生产工艺技术和特点,以及他们的调味增香机理,从西式肉制品的产品风味、成本及创新等方面阐述了应用肉味调味料的必要性,利用其天然、营养,耐高温等优势,通过牛肉火腿肠生产工艺配方应用举例,确定热反应牛肉粉、牛肉膏在西式肉制品中广泛的应用前景.     

Moisture sorption isotherm of fresh lean beef and external beef fat

The moisture sorption isotherm (MSI) of lean beef and fat beef was experimentally determined. The experimental procedure used was that of the COST 90 project with some modifications to accelerate equilibration. The procedure was validated with the standard reference material microcrystalline cellulose. The MSI of the beef at the highest humidity range was obtained by accelerating equilibration with changes of salts, using a low water activity salt for some time. This procedure was reliable for beef samples but not for the fat samples. No significant changes were found for lean beef in the temperature range 5–40 °C. Three models, GAB, Peleg and Lewicki, were used to fit the experimental data. The best fit was obtained with the GAB equation. The fat MSI was determined at 5, 15 and 25 °C and it was best fitted with the Lewicki model.     

Microbiological characterization of imported and domestic boneless beef trim used for ground beef

The United States imports lean boneless beef trim from Australia (AUS), New Zealand (NZL), and Uruguay (URY) to meet demand for ground beef production. The reported incidence of and etiological agents responsible for foodborne diseases differ between these countries and the United States. Our objective was to determine whether current U.S. microbiological profiling adequately addresses the potential differences between foreign and domestic beef trim. We compared the hygienic status of imported and domestic (USA) beef trim by enumeration of aerobic bacteria, Enterobacteriaceae, coliforms, Escherichia coli, and Staphylococcus aureus. We also compared the prevalence of pathogens between imported and domestic samples by screening for the presence of Salmonella, Campylobacter spp., Listeria spp., and non-O157 Shiga toxin-producing E. coli (STEC). A total of 1,186 samples (487 USA, 220 AUS, 223 NZL, and 256 URY) of boneless beef trim were analyzed. Results of enumeration revealed significant differences between samples from all countries, with the lowest pathogen numbers in samples from AUS and the highest in samples from URY. Six Salmonella isolates (1 NZL, 1 URY, and 4 USA), 79 L. monocytogenes isolates (4 AUS, 5 NZL, 53 URY, and 17 USA), and 7 Campylobacter isolates (1 NZL, 1 URY, 5 USA) were found among the trim samples tested. Non-O157 STEC prevalence was 10% in NZL samples and about 30% in all of the other samples; 99 STEC strains were isolated. Serotyping of these isolates revealed that serotypes associated with hemolytic uremic syndrome were not different in prevalence between imported and domestic beef trim. Although it may be tempting to do so, these data cannot be used to compare the microbiological quality of beef trim between the countries examined. However, these results indicate that the current pathogen monitoring procedures in the United States are adequate for evaluation of imported beef trim.     

Salmonella prevalence in seafood imported into Japan

A total of 353 samples of 29 types of seafood were tested for Salmonella prevalence and total microbial population. Salmonella enterica serotype Weltevreden was isolated from 2 of 47 black tiger prawn samples. The contamination levels of Salmonella were in a range of <30 to 40 most probable number per 100 g. In addition, one sample of black tiger prawns and two samples of white shrimp were positive for Salmonella invA gene on PCR assay. Although the mean aerobic bacterial count was greater than 4 log CFU/g in most of the sample types, those in the two Salmonella-isolated samples of black tiger prawn were 7.48 and 5.18 log CFU/g, respectively. These results indicate the possibility that shrimp and prawns contribute to foodborne infections. The improvement of seafood quality is an important issue, and the information on contamination by pathogens should be provided as feedback to the originating country, with the aim of increasing safety.     

我国进口干酪制品中硝酸盐、亚硝酸盐含量调查及暴露风险评估研究

目的 了解我国进口干酪制品中硝酸盐、亚硝酸盐含量水平,并评估我国成人干酪消费人群健康风险。方法 基于我国市售的进口干酪制品中硝酸盐、亚硝酸盐含量和2012年我国居民干酪消费量数据,通过概率评估方法,对我国成人干酪消费人群的膳食硝酸盐、亚硝酸盐暴露量进行估计,并分别与联合国粮农组织/世界卫生组织食品添加剂联合专家委员会（JECFA）制定的硝酸盐每日允许摄入量（ADI）和欧洲食品安全局（EFSA）制定的亚硝酸盐ADI比较后进行风险表征。结果 162份进口干酪样品中,硝酸盐的检出率为89.5%,平均含量为11.23 mg/kg;亚硝酸盐仅2份检出,含量为0.4和0.6 mg/kg。不同种类进口干酪制品中硝酸盐的平均含量从高到低依次为软质、半硬质、其他、硬质。我国成人通过进口干酪硝酸盐的平均暴露量为5.13 μg/kg BW/d,占ADI的0.14%,高暴露人群（P95）为20.06 μg/kg BW/d,占ADI的0.55%。结论 我国进口干酪制品中硝酸盐的检出率较高,且不同种类进口干酪制品其含量存在差异,而亚硝酸盐检出率很低。我国成人通过进口干酪暴露硝酸盐的健康风险较低。     

Thermal process validation for Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes in ground turkey and beef products

At 55 to 70 degrees C, thermal inactivation D-values for Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes were 19.05 to 0.038, 43.10 to 0.096, and 33.11 to 0.12 min, respectively, in ground turkey and 21.55 to 0.055, 37.04 to 0.066, and 36.90 to 0.063 min, respectively, in ground beef. The z-values were 5.73, 5.54, and 6.13 degrees C, respectively, in ground turkey and 5.43, 5.74, and 6.01 degrees C, respectively, in ground beef. In both ground turkey and beef, significant (P < 0.05) differences were found in the D-values between E. coli O157:H7 and Salmonella or between E. coli O157:H7 and L. monocytogenes. At 65 to 70 degrees C, D-values for E. coli O157:H7, Salmonella, and L. monocytogenes were also significantly (P < 0.05) different between turkey and beef. The obtained D- and z-values were used in predicting process lethality of the pathogens in ground turkey and beef patties cooked in an air impingement oven and confirmed by inoculation studies for a 7-log (CFU/g) reduction of E. coli O157:H7, Salmonella, and L. monocytogenes.     

Salmonella spp. shedding by alberta beef cattle and the detection of Salmonella spp. in ground beef

Breeder cows, cattle recently arrived at feedlots, and cattle about to be shipped for slaughter were tested for Salmonella spp. No Salmonella spp. were detected in fecal samples from breeding cows. Nineteen of 1,000 (1.9%) fecal samples from recently arrived feedlot cattle were positive for Salmonella spp. compared to only 2 of 1,000 (0.2%) fecal samples taken within 2 weeks of slaughter. The positive fecal samples were collected in 5 of 50 (10%) "recent arrival" pens tested and in 1 of 50 (2%) pens tested within 2 weeks of slaughter. The serotypes isolated were Salmonella Agona, Salmonella Enteritidis, Salmonella Typhimurium DT104, and Salmonella 4,5,12:i:-. Ground beef samples purchased from retail outlets throughout Alberta were processed for Salmonella spp. Thirteen of 1,002 (1.3%) samples were positive for Salmonella spp. The serotypes isolated from ground beef were Salmonella Anatum, Salmonella Heidelberg, Salmonella Montevideo, Salmonella Typhimurium, Salmonella Typhimurium var. Copenhagen, and Salmonella Rough-O:i:1,2. The antibiotic resistance and pulsed-field electrophoresis gel macrorestriction patterns of all isolates were compared.     

高档牛肉制品应该注重"嫩"、"鲜"、"特"

虽然我国是仅次于美国的世界第二牛肉生产大国,但我国牛肉全年人均消费量尚不及世界平均水平的1/3,我国牛肉的出口量呈迅速增长的态势。然而我国目前在国内、国外销售的主要是未经深加工的“冻牛肉”,很少有精深加工的牛肉制品,其利润率很低。日本某包装牛肉产品。每公斤的价格     

Composition and quality of Mexican and imported retail beef in Mexico

Randomly selected New York steaks from domestic and imported beef were purchased in three major Mexican cities, comparing Mexican beef (from northern, central, and southern regions of the country) and American beef (USDA-Choice and ungraded No Roll). The meat was analyzed for chemical composition, Warner-Bratzler shear force (WBSF), cooking loss, color and consumer acceptability. All sources of Mexican beef and No Roll US beef had similar chemical composition. USDA-Choice beef had a higher fat content and a lower moisture and total collagen content. Mexican beef from the northern region and USDA-Choice beef had lower WBSF and redness values than the other beef sources. Overall desirability was high regarding all Mexican beef sources, and USDA-Choice beef. No Roll US beef had the lowest overall desirability score. Results indicate Mexican beef is in an advantageous position when competing with imports in the current open market.     

Factors associated with surface iridescence in fresh beef

The objective of this study was to investigate factors associated with surface iridescence in fresh beef. Eight muscles were evaluated for occurrence of surface iridescence: Biceps femoris (BF), Gluteus medius (GM), Longissimus lumborum (LD), Psoas major (PM), Rectus femoris (RF), Semimembranosus (SM), Semitendinosus (ST), and Tensor fasciae latae (TF). Incidence of surface iridescence was 91% for ST, 34% for SM, 27% for LD, 20% for GM, 12% for RF, 9% for BF, 8% for TF, and 6% for PM (P<0.05). Factors associated with surface iridescence in the ST were further examined because iridescence was observed to a much higher degree in the ST as compared with other muscles evaluated. Greater ST surface iridescence was associated with larger ribeye areas, more youthful lean maturity scores, higher L^*, a^* and b^* colorimeter values, lower ultimate pH values, and faster cooking (P<0.05).     

Dye use in fresh meat preparations and meat products: a survey by a validated method based on HPLC-UV-diode array detection as a contribution to risk assessment

The use of dyes in meats has to be monitored, due to food safety concerns. The presence of twelve dyes (Amaranth, Ponceau 4R, Carmine, Ponceau SX, Ponceau 3R, Allura Red AC, Carmoisine, Erythrosine, Sudan I, Sudan II, Sudan III and Sudan IV) in meat was investigated in 130 meat product and fresh meat preparation samples, and the dietary exposure was estimated. Carmine and Ponceau 4R were the identified dyes. Except for one sample of salami, they were regularly indicated on the label, and their concentrations were in the range 1.3–8.1 and 6.2–86.4 mg kg⁻¹ for Ponceau 4R and Carmine, respectively. Concerning fresh meat preparations, Carmine was detected in three samples, confirming that this dye is still used, although it is no longer authorised in these products. Regarding dietary exposure estimate, the daily intake from meat product consumption resulted lower than 1% of the ADI, both for Carmine and Ponceau 4R.     

PCR法快速检测超市生鲜牛肉卷和腌制牛肉片

通过扩增线粒体DNA片段,建立了检测生鲜牛肉和腌制牛肉片中掺入猪肉的快速检测PCR的方法。反应程序为:94℃预变性4min,然后经过30个循环,每个循环为94℃变性30s,退火温度为59.4℃反应30s,延伸温度72℃反应30s,30个循环后72℃保温延伸7min,通过电泳进行检测。经过多次实验,结果表明:所选定的引物只有在同一种属模板DNA存在的情况下才会发生PCR扩增,该方法特异性强、稳定、灵敏度高。本方法简单快速,无需酶切,适用于样品较多的检测。