Effects of microwave energy on the relative stability of vitamin E in animal fats

The relative stabilities of individual tocopherols during microwave heating were evaluated in purified animal fats. Each tocopherol (α, β, γ and δ) was added to the purified beef tallow and lard at 0.25 μmol g^?1 fat immediately before use. During microwave heating the highest rate of loss was shown by α-tocopherol, followed by γ-, β- and δ-tocopherols. This order did not depend on the types of fats present. The indices such as peroxide value, carbonyl value and anisidine value for assessing quality of fats showed a significant difference (P < 0.05) in the final stage (12–20 min) of heating. It is therefore necessary that particular attention be paid to the loss of vitamin E when cooking pork or beef in a microwave oven.     

Taxonomy, ecology and antibiotic resistance of enterococci from food and the gastro-intestinal tract

Apart from genotypic identification methods, there is a need for reliable conventional phenotypic identification schemes for simple and rapid determination of enterococcal species in food or in the gastro-intestinal tract (GIT). Only a limited number of enterococcal species is of importance for the ecology of the GIT or the food microflora, including E. faecalis, E. faecium, E. durans/hirae, E. gallinarum and E. casseliflavus. After genus identification the differentiation within these species can include, e.g. mannitol and arabinose fermentation and growth at 50 degrees C. Widely used commercial identification systems may fail to precisely identify rare species. Ecological aspects should also be taken into account. In the human GIT E. faecium is the most common species whereas in most animal species E. faecalis is at least present in the same amount. Especially in foods of animal origin (cheese, pork meat, beef, poultry meat) also E. faecalis is very frequent. This is of special interest as glycopeptide resistance is most often found in human clinical E. faecium strains as well as in E. faecium from the environment or animal samples and less frequent in E. faecalis strains. EU experts propose as safety criteria for probiotics in feed additives the exclusion of resistances or the lack of transferability. This proposal can also be applied to enterococci in foods. Specific resistances must be excluded, but transferability or acquisition of resistance (e.g. vancomycin) cannot be excluded per se. However, technologically used strains should differ from clinical strains concerning their resistance patterns and transfer rates.     

PROCESSING, CHEMICAL, SENSORY AND PHYSICAL PROPERTIES OF BACON-CHOPPED AND FORMED, MADE FROM PORK, BEEF, MUTTON AND CHEVON

By extruding alternating layers of chopped lean and fat tissue, bacon-chopped and formed (CF) products were processed from pork, beef, mutton and chevon lean and beef fat. Slabs processed from beef materials had less weight loss and changes in width and thickness during smoking than the other formulations. Various sensory and consumer panels found pork-bacon-CF product to rate highest among the four formulations for tenderness, flavor and overall satisfaction. This formulation was rated as being closest in sensory traits to commercial bacon. Chevon and mutton bacon-CF products were found to be less desirable in flavor. Inclusion of pork lean and fat with chevon and mutton lean can potentially improve the acceptability of bacon-CF processed with lean from these two species. However, this process and product appears promising as methods of increasing consumption of underutilized meat animal species.     

驴肉主要营养成分及与其它畜禽肉的分析比较

本文测定了驴肉的水分、灰分、蛋白质、粗脂肪、脂肪酸、矿物元素、氨基酸的含量,并将驴肉与其他畜禽肉的营养成分作对比分析。结果表明:驴肉蛋白质含量比羊肉、牛肉、猪肉高,而脂肪含量比羊肉、牛肉、猪肉低。驴肉的氨基酸和脂肪酸组成是比较理想的,矿物元素中Fe含量明显高于其它畜禽肉。从营养学角度看,驴肉是比较理想的动物性食品原料。     

SELECTED SENSORY AND CHEMICAL ATTRIBUTES OF CHICKEN BREAKFAST SAUSAGES FROM DIFFERENT ANIMAL FAT SOURCES

Four breakfast sausage formulations were prepared to contain: (1) chicken lean + chicken fat (CF), (2) chicken lean + beef fat (BF), (3) chicken lean + pork fat (PF), or (4) chicken lean + high-oleic pork fat (PO). Formulations were targeted to contain 15% fat. Acceptability, tenderness, juiciness and flavor scores for each of the formulations as measured by a consumer taste panel (n = 71), were not different (P> 0.05). Sausages prepared with CF had a higher (P < 0.05) cooking loss and lower fat content than those prepared with BF. Thibarbituric acid (TBA) values for PO were significantly lower than those containing BF, PF, or CF. Sausage products containing chicken fat exhibited the highest TBA values during 9 days of storage at 4°C. These results suggested that chicken, beef, pork or high-oleic fats can be used as the fat source in low-fat chicken breakfast sausages without affecting the product acceptability.     

The effects of curing and cooking on the detection of species origin of meat products by competitive and indirect ELISA techniques

The purposes of this study were: (1) to develop and compare competitive and indirect enzyme linked immunosorbent assay (ELISA) methods for detecting species specific albumins in meat samples and (2) to examine the effect of curing and cooking on the identification of species origin of meats. Commercially obtained rabbit anti-pig serum albumin (anti-PSA) and rabbit anti-sheep serum albumin (anti-SSA) were affinity purified, and used to develop competitive and indirect ELISA procedures for PSA and SSA. The competitive ELISA procedures showed the lowest cross-reactivity with related serum albumins. Both ELISA procedures were capable of detecting as little as 5% pork or sheep in beef. Curing resulted in little or no inhibition in the ability of ELISA procedures to detect pork or sheep in beef. Cooking completely eliminated the ability of the competitive PSA ELISA to detect pork in beef, and of both SSA ELISA procedures to detect sheep in beef. Cooking also greatly reduced, but did not eliminate, the ability of the indirect PSA ELISA to detect pork in beef. Curing and cooking essentially eliminated the ability of the PSA ELISA procedure to detect pork in beef. Curing and cooking resulted in a 70 to 74% decrease in the signal of sheep meat in SSA ELISA procedures. These results demonstrated that competitive and indirect ELISA procedures are capable of determining the species origin of raw and cured meat. Heating raw or cured meats greatly reduced, but did not always eliminate, the ability of ELISA procedures to detect species origin of meats.     

Organoleptic Identification of Roasted Beef, Veal, Lamb and Pork as Affected by Fat

SUMMARY— A taste panel was used to study the identification of roasted beef, pork, lamb and veal by flavor alone and the effect of fat on identification. Only about one-third of the panel could identify correctly all four meats by memory of the flavors. There was an increase in the total number of correct identifications made by comparison of the unknown roasted meat samples with known standards but this was not significantly greater than the total correct responses by memory of the flavor alone. Beef and lamb, but not pork and veal, were identified significantly less often when lean ground roasts were tested than when normal ground roasts (containing fat) were used. Texture, color, mouth feel, and other factors may be important in the identification of meat. Beef, lamb and pork fat, as well as these fats after extraction with chloroform: methanol, were added to lean veal prior to roasting. Addition of beef fat did not increase recognition of veal as beef. Pork fat contained a factor increasing identification of veal as pork, but this factor was water-soluble and could be removed. Lamb fat contained a component, or a fat-soluble component, that significantly increased the identification of veal as lamb.     

Differentiation of cattle species in beef by PCR-RFLP of mitochondrial and satellite DNA

Methods currently used for the identification of the species origin of meat or tissue samples have not been validated for other bovine species than taurine cattle or water buffalo. These methods also do not discriminate between the different bovine species that are used as source of beef. Here, we describe two complementary methods for detection and differentiation of bovine species, which are based on mutations in mitochondrial DNA and centromeric satellite DNA, respectively. The analysis of satellite DNA is especially relevant for the identification of animals that are of hybrid origin.     

Properties of Low-Fat Frankfurters Containing Monounsaturated and Omega-3 Polyunsaturated Oils

Properties of low-fat (<18%) frankfurters containing high-oleic acid sunflower oil (HOSO) and fish oil were studied. Replacement of animal fats by the oils had little effect on emulsion stability. Frankfurters with 5% fish oil had very low sensory scores due to undesirable fish flavor. Incorporation of maximum amounts of HOSO into low-fat beef/pork and all-beef frankfurters increased oleic acid by 34% and 62%, respectively, and the monounsaturated/saturated fatty acid ratio by 178% and 468%, respectively, compared to a regular (30% fat) product containing only animal fats. Sensory evaluation and instrumental texture profile analysis showed that the reduction in total fat caused texture problems, especially increased firmness and springiness and decreased juiciness.     

朊蛋白疾病及其肉食品安全的研究进展

英国疯牛病造成了人类疾病传播的潜在危害,牛羊肉等肉食品的安全备受关注。为了避免疯牛病污染的肉品进入食物链,世界多个研究小组对各类肉食品开展了基于疯牛病传播因子安全方面的研究。疯牛病患病牛肉可以直接感染人类并导致发病,阳性病牛应彻底销毁并进行无害化处理,严禁进入食物链。染病的羊肉和鹿肉属于高度危险食品,也应做销毁处理,而猪肉、马肉、兔肉和水牛肉等则相对比较安全。同时,朊蛋白疾病的感染还与人类自身朊蛋白编码基因多态性有关。在严格检疫的同时,培育抗病品种的家畜以及食用不易感的肉类食品成为未来肉食品安全的一种发展趋势。本文总结了疯牛病、痒病等可传播海绵状脑病患病动物的肉用安全性,还分析了疯牛病可能突破种间屏障而造成跨物种传播的可能性,为肉食品安全及检疫提供参考。     

Distribution of fatty acids in lipids as an aid to the identification of animal tissues. I.—Bovine,porcine, ovine and some avian species

Fat was extracted from various cuts of meat, from domestic and foreign sources. The majority of the samples were of pork, beef and lamb, but specimens from rabbit, various species of poultry, and three African ruminants, were also prepared. The fatty acid compositions of the samples were determined by gas-chromatography of their methyl esters, on polar and non-polar stationary phases. The use of such results both for the identification of the animal source of meat, and of the purity of lard samples, is discussed. It is suggested that the presence of lard in certain branched-chain fatty acids, characteristic of ruminant fat, provides evidence of adulteration with beef or mutton tallow.     

基于PCR技术的肉类成分溯源鉴定方法研究进展

近几年屡屡曝光的食品安全事故引起了社会的广泛关注,食品安全已经成为社会共同关注的问题,肉类掺假造假现象更是层出不穷,其中用低价鸡肉、鸭肉、猪肉等掺入、冒充牛羊肉成为主要的掺假方式。国内外进行肉类掺假鉴定主要以核酸作为靶标,核酸鉴定也是物种鉴别最常用、最核心的方法,以DNA检测为基础建立起来的DNA条形码、多重PCR、荧光定量PCR、荧光探针等技术也得到空前发展和广泛应用。我国针对动物源性成分检测也制定了相关国家标准和行业标准,但大多现行标准中基于DNA检测建立的PCR技术只能检测单一物种,滞后于技术的发展。目前,基于PCR发展起来的衍生技术凭借其高灵敏度、强特异性和高通量等优势在动物源性成分检测工作中显示出巨大潜力,也是肉类成分鉴定未来的重要方向。本文综述了PCR技术在肉类检测中的研究概况和现行标准的技术概况,以期为肉类成分鉴定研究提供信息。     

Palatability and Appearance Traits of Beef/Pork Meat Patties

Eight beef/pork ground meat blends were made from mature (cows or sows) and youthful (steers or barrow) beef and/or pork lean. Blends were stored at — 27°C for either 14 or 150 days. Storage time decreased overall desirability scores of blends made with 20% pork fat and 80% youthful beef lean. No differences were found for flavor or overall desirability scores within the 14-day storage treatment. The consumer panel did not detect differences among treatments for source of fat or species. Results indicated beef/pork patties containing 40–80% mature lean and a minimum of 10% beef fat were equal to all-beef controls (100% beef patty) for visual and palatability traits.     

Effect of Fat Source and Color of Lean on Acceptability of Beef/Pork Patties

Twelve beef/pork meat blends were made from lean of mature beef and dark or mature pork carcasses. Meat blends containing about 20% beef fat were rated higher for appearance scores by a consumer panel than blends made with 20% pork fat. Visual acceptance of beef/pork patties was accomplished via use of all-beef fat and additionally by extending mature beef (MB) with mature pork (MP) or dark pork lean (DP). Agtron calorimetry scores indicate a minimum of 20% MB lean extended with 60% MP was needed to create the appropriate red color attractive to consumers. Use of 60% MP lean with about 20% beef fat resulted in patties acceptable to consumers for visual appearance and eating satisfaction.     

Conventional and real-time PCR-based approaches for molecular detection and quantitation of bovine species material in edible gelatin

The majority of edible gelatin in Europe is derived from pigskin, but a significant portion is extracted from bovine tissue. Because of the bovine spongiform encephalopathy crisis, consumers might be concerned about the gelatin used in various products. To assure consumers of the quality and safety of edible gelatin, European Union directive 1999/724/EC described general guidelines for gelatin production, including requirements for documentary proof confirming that raw materials are from animals fit for human consumption. Analytical methods to confirm gelatin documentation or raw material animal species source in the finished product are lacking. In this study, several published species-specific PCR systems were evaluated as potential molecular methods for determining the origin of the raw material used in making gelatin. A recently validated bovine species-specific PCR primer set targeting the ATPase 8 subunit gene in bovine mitochondrial DNA was suitable for detection of bovine material in gelatin. This PCR primer set was optimized using conventional and real-time PCR approaches. An evaluation of these two PCR methods confirmed the high specificity for the adopted primer set in various gelatin matrices of known origin. The inclusion of bovine gelatin in pork or fish gelatin can be detected at 0.1 to 0.001%. These PCR assays are potential molecular detection tools that can be used to routinely detect bovine gelatin either alone or as an inclusion in gelatin made from other species.     

On-line NIR analysis of fat, water and protein in industrial scale ground meat batches

Fat, water and protein contents in industrial scale meat batches were determined on-line by near infrared (NIR) reflectance spectroscopy. The NIR instrument was mounted at the outlet of a large meat grinder, and the measurements were performed in an industrial environment. Beef and pork samples, with chemical compositions of 7-26% fat, 58-75% water and 15-21% protein, were processed with hole diameters of 13mm in the grinder plate. Calibrations were made both for a combined set of beef and pork samples, and for separate sets of beef and pork samples. Validations were either done by full cross validation of the calibration set, or by bias corrected prediction of a test set. Prediction errors for the two sample sets, expressed as root mean square errors of cross validation or standard error of prediction, were in the ranges 0.82-1.49% fat, 0.94-1.33% water and 0.35-0.70% protein, depending of sample set and species of animal. The presented application is an improvement to the existing manual meat standardisation procedure, and has been implemented for regular use in a Norwegian meat manufacturing plant.     

2013年苏州地区肉及其制品掺假情况调查

了解苏州地区肉及其制品的掺假情况,通过对肉类种源与标签明示肉源进行比对,鉴别摻假食品,为加强食品标签管理提供依据。方法 运用自建的动物源性食品种源判定Taqman实时荧光PCR检测体系对苏州地区的肉及其制品进行种源判定,与标签明示肉源进行比对,鉴别摻假食品。结果 本次调查共检验涉及32个生产单位的90份样品,总不符合率为25.6%(23/90)。检测的44份牛肉及其制品中有12份与标签不符,8份用猪肉部分替代牛肉,1份以鸭肉部分代替牛肉进行销售;此外有3份不含有牛肉成分,存在猪、鸡、鸭源性肉类之外的肉类成分。共检测羊肉及其制品16份,有2份用鸭肉代替羊肉出售,3份羊肉样品中掺入了部分猪成分,其中1份样品还存在单个样品掺杂两种外源肉类的现象(猪源性和鸭源性)。检测猪肉及其制品19份,其中2份样品含有标签未注明的鸡肉成分。在所检测的11份混合肉类样品中有4份成分与标签不符,主要是以廉价的鸡肉取代/部分取代相对高价的牛肉和猪肉。结论 肉制品掺假情况明显,用猪肉、鸭肉部分代替牛肉和羊肉仍是主要的掺假手段,牛肉掺假样品主要是熟制牛肉制品,而火锅食用羊肉卷样品则是羊肉掺假高危品,开展肉制品摻假检测对规范肉制品市场具有积极意义。此外,3份未知种源成分的牛肉样品提示在现有检测基础上还需扩大检测范围,防患于未然。     

DETECTION OF SPECIES ADULTERATION IN PORK PRODUCTS USING AGAR-GEL IMMUNODIFFUSION AND ENZYME-LINKED IMMUNOSORBENT ASSAY

Mixing undeclared species in meat products is illegal under food labeling regulations. This study compared the conventional agar-gel immunodiffusion (AGID) with the Enzyme-Linked Immunosorbent Assay (ELISA) for detecting species adulteration and assessed the species adulteration problem in raw ground pork products in Alabama retail markets. Forty-two ground pork and 87 fresh pork sausage samples collected throughout Alabama were examined by AGID and ELISA for four species: pork, beef, poultry and sheep. Using ELISA, 91 % of the ground pork samples were found to contain other meats while 71 % were found to be contaminated using AGID. Using ELISA, 54% of the sausage samples were found to contain undeclared species while none were found to be contaminated using AGID. The major adulterating species in the pork products was beef followed by poultry and sheep. Reliable analytical methods, such as ELISA, must be used as a regulatory tool to discourage the meat species adulteration problem in retail markets.     

EFFECTS OF TYPES AND LEVELS OF FAT AND RATES AND TEMPERATURES OF COMMINUTION ON THE PROCESSING AND CHARACTERISTICS OF FRANKFURTERS

ABSTRACT— Frankfurter emulsions containing either 25% or 35% beef fat, pork fat, or cottonseed oil were prepared by comminuting at 1500, 2500, or 5000 rpm to temperatures ranging from 45°–85°F. Data were obtained on the viscosities of the emulsions; except for initially high viscosities for which unmelted fat was responsible, the viscosities of emulsions containing the fats, or oil, were similar: viscosities tended to decrease with increasing time and temperature of chopping. The frankfurters were stuffed, smoked, and cooked, and data were obtained on shrinkage, fat retention, ease of peeling, specific gravity, and texture. Shrinkage was inversely related to content of fat. Fat separation mainly occurred in processing frankfurters containing beef fat; the data suggest that emulsions containing beef fat should be comminuted to 65°–75°F to avoid possible under or overchopping: the results show that optimum conditions were time as well as temperature dependent. The air content of frankfurters varied inversely with the maximum temperature attained during communition. Frankfurter skin strength was lessened on increasing the temperatures to which emulsions were communited; elasticity, the equivalent of rubberiness, decreased under these conditions.     

EFFECTS OF TYPES OF FAT AND OF RATES AND TEMPERATURES OF COMMINUTION ON DISPERSION OF LIPIDS IN FRANKFURTERS

ABSTRACT— The effect of time, temperature and rpm of comminution of emulsions was determined on the dispersion of approximately 25% of beef fat, pork fat or cottonseed oil in frankfurters. The numbers of lipid particles 5 μ or less in diameter increased in frankfurters containing either beef or pork fat as comminution was continued to higher temperatures, with pork fat dispersed more thoroughly. Fat tended to separate from frankfurters containing beef fat in particles 200 μ or more in diameter. In contrast, no specific degree of dispersion of particles 5 μ or less in diameter consistently indicated emulsion stability, or its lack. Increased rpm during comminution produced an increased dispersion of beef or pork fat. Under the same conditions pork fat was dispersed more finely than beef fat. Dispersion of cottonseed oil produced finely dispersed particles beyond the resolution of light microscopy, as was confirmed by electron microscopy which showed a substantial number of particles to be less than 1 μ in diameter.