Construction, management and cleanliness of red meat abattoir lairages in the UK

A survey of a large number of UK abattoirs was conducted via a questionnaire designed to obtain information on (i) throughput and species slaughtered; (ii) construction materials used; (iii) use and type of bedding and (iv) details of cleaning/sanitation regimes. A representative group of abattoirs were selected on the basis of the responses to the questionnaire, and the lairage at these plants investigated through enumeration of Escherichia coli remaining after routine cleansing operations. The aim of this study was to enable identification of "common lairage practices" and to assess the general status of the lairage hygiene and effectiveness of lairage cleaning in commercial UK abattoirs. The study shows that microbial contamination often remains in UK lairage holding pens after routine cleaning operations. It would appear that there are significant differences in the effectiveness of lairage cleaning programmes at commercial abattoirs, and that the stun-box-roll-out areas are often cleaned to a better standard than the holding areas. As a result of persistence of microbial contamination in the lairage, there is a possible risk of foodborne pathogens persisting in the environment and potentially contaminating animals and carcasses processed on subsequent days.     

浅谈低压泡沫清洗消毒技术在肉类工业中的应用

简要介绍了低压泡沫清洗消毒技术的原理及特点,分析了其在肉类加工工业中的使用方法和优势。     

肉品品质评定方法研究进展

肉类产业是食品产业的重要支柱,世界范围内肉类的人均年消费量接近30 kg,随着世界经济的不断发展,肉类消费量也具有很大的提升空间。肉品的品质是影响消费意欲的重要因素,肉品品质评定方法的建立对肉类食品的健康发展具有十分重要的意义。目前国内外关于肉品品质的评定方法研究主要是针对猪、牛、鸡、鸭等大宗产品,其中对猪肉、牛肉的品质研究较为全面,有相对完整的评定体系,其他畜禽肉的评定方法则主要参考猪肉和牛肉的指标,考虑到不同物种的差异性,最终的评价结果可能会有较大差异。本文综述了肉色、p H值、系水力和嫩度等主要肉品品质指标的评定方法及相关影响因素,并将不同评定方法的测定条件和结果进行了比较,为肉品品质评定体系的建立及完善提供参考依据。     

Microbial methods for assessment of cleaning and disinfection of food-processing surfaces cleaned in a low-pressure system

 An assessment system using various microbial methods was developed for the detection of residual, surface-attached microbes and soil on surfaces after sanitation. The microbial methods tested were: conventional cultivation, microscopy using image analysis after staining with acridine orange (AO), 5-cyano-2,3-ditolyl tetrazolium chloride/4′, 6-diamidino-2-phenylindole (CTC-DAPI) and LIVE/DEAD stains, impedance measurements, viable counts with 2,3,5-triphenyltetrazolium chloride (TTC) agar and ATP measurements. A test rig was used for the trials with four different low-pressure cleaning procedures (pressure <20 bar flow rate 27 l min^–1). A strong alkaline foam cleaner, Trippel, and a mild alkaline foam cleaner, Topax 12, in combination with two disinfectants, respectively, were used. The disinfectants were peroxide-peracetic-acid-based Oxonia Aktiv and potassium-persulphate-based Virkon. Conventional cultivation combined with impedance measurements and image analysis of surfaces stained with AO, as well as CTC-DAPI, gave results that were comparable and complementary. The combination of these methods enabled a total evaluation of both the removal of biofilm and the killing of bacterial cells. The low-pressure cleaning system did not remove all of the bacterial cells from the surfaces and did not kill the bacteria even after use of the strong alkaline foam cleaner. The above-mentioned protocol carried out on the test rig can also be used to evaluate the sensitivity of microbial methods for use in certain industrial premises. Received: 22 July 1998 / Revised version: 14 September 1998     

Effects of lairage time on welfare indicators,energy metabolism and meat quality of pigs in Beijing

A total of forty Duroc–Landrace–Large White female pigs (90 ± 5 kg) were used to study the effects of different lairage times (0 h, 3 h, 8 h, 24 h) on welfare, energy metabolism and meat quality. The results showed that lairage time of 3 h led to a lower blood cortisol, a decreased drip loss and a delayed degradation of glycogen in muscles compared with pigs without rest, while lairage times of 8 h and 24 h resulted in a significant increase in pork toughness. It was concluded that three hours of lairage was appropriate to reduce pre-slaughter stress and obtain better meat quality for pigs transported for 4 h in winter, under the most frequent commercial conditions in Beijing, China. No lairage, or excessively long lairage time, might compromise animal welfare and meat quality.     

Computerized diffractometer for measurements of sarcomere lengths in meat: An evaluation of data reduction methods

A computerized laser diffractometer was evaluated on the basis of two different theoretical models for light diffraction in muscle tissue. It was shown that the method of computing sarcomere lengths from the positions of the left and right first order diffraction lines is model dependent. Sarcomere lengths obtained by the diffractometer were compared to microscopically determined sarcomere lengths on freeze-sectioned M. sternomandibularis from a material consisting of muscle strips held at different degrees of stretch. Treating left and right diffraction lines as independent observations led to the determination of sarcomere lengths with negligible deterministic error. The possibility of utilizing the fine structure and intensity of the diffraction patterns to improve the sarcomere length determination and provide more relevant information is discussed.     

Measurement uncertainty of the EU methods for microbiological examination of red meat

Three parallel trials were made of EU methods proposed for the microbiological examination of red meat using two analysts in each of seven laboratories within the UK. The methods involved determination of aerobic colony count (ACC) and Enterobacteriaceae colony count (ECC) using simulated methods and a freeze-dried standardised culture preparation. Trial A was based on a simulated swab test, Trial B a simulated meat excision test and Trial C was a reference test on reconstituted inoculum. Statistical analysis (ANOVA) was carried out before and after rejection of outlying data. Expanded uncertainty values (relative standard deviation x2) for repeatability and reproducibility, based on the log10 cfu/ml, on the ACC ranged from +/-2.1% to +/-2.7% and from +/-5.5% to +/-10.5%, respectively, depending upon the test procedure. Similarly for the ECC, expanded uncertainty estimates for repeatability and reproducibility ranged from +/-4.6% to +/-16.9% and from +/-21.6% to +/-23.5%, respectively. The results are discussed in relation to the potential application of the methods.     

An evaluation of methods for the detection of spinal cord in product derived from advanced meat recovery systems

This study investigated the usefulness of immunohistochemistry, histochemistry, and polarization microscopy in documenting the presence of spinal cord in ground product produced by advanced meat recovery systems (AMRS). A battery of diagnostic stains proved most helpful for definitive documentation of spinal cord in the AMRS product. Antibodies to neurofilament and glial fibrillary acidic proteins were useful for highlighting the presence of neural tissue in comminuted product but when used alone did not definitively differentiate central nervous system tissue from peripheral nerve. Polariscopy, trichrome staining, and immunostaining for synaptophysin were very useful for differentiating spinal cord from peripheral nerve. Spinal cord was found in 2 of 196 AMRS samples when only hematoxylin and eosin staining was used. In a later immunohistochemical subset of the survey study, spinal cord was found in 7 of 17 AMRS samples. More recently, spinal cord tissue has been found in 3 of 26 regulatory samples using hematoxylin and eosin stains combined with immunohistochemical techniques.     

Identification of cohesive and adhesive effects in the cleaning of food fouling deposits

Cleaning of process plants is costly and time consuming. It is important to understand the removal of fouling deposits. Deposits form by adhesion to the surface and cohesion between elements of the deposit. Cleaning can result from either or both adhesive and cohesive failure. Micromanipulation experiments have measured the adhesive/cohesive strength of deposits in terms of the work required to remove them from the surface. Different food deposits have been studied. Tomato paste, bread dough and egg albumin deposits have a lower adhesive than cohesive strength, whilst others (whey protein) have a lower cohesive than adhesive strength. A range of coated surfaces has been used to study the effect of surface energy on the force required for removal of tomato deposits. Minima are found, as predicted by theory. A simple material model has been developed and used to analyse the results in terms of the work required to remove the deposit per unit surface area and volume.

Industrial relevance

Cleaning is a ubiquitous and poorly understood operation in the food industry. Poor cleaning endangers product safety, lowers run length and generates excess effluent. Better understanding of the processes of cleaning is beneficial both in ensuring food safety and in increasing the manufacturing efficiency of process plant.     

Proteins in developing sorghum endosperm that may be involved in resistance to grain moulds

The level and type of fungal infection on grains varying in hardness at different stages of development over two seasons has been studied. Hard grains showed less incidence of grain moulds than soft grains during development. Microscopic examination showed more intense deposition of protein bodies in hard than in the soft grains. The presence of fungal hyphae in the endosperm of soft grains and pitted starch granules was clearly visible microscopically. Extracts of immature and mature hard and soft endosperm were inhibitory to Fusarium moniliforme growth. These inhibitors were heat labile and non-dialysable indicating that protein factors may be involved. The activities of inhibitors to serine proteases were comparatively higher in endosperm of hard grains during development. The endosperm of hard grains contained more protein and prolamine than that of soft grains. A role for proteins in resistance of fungal infection in low tannin lines is presented.     

An X-Y paint set and sperm FISH protocol that can be used for validation of cattle sperm separation procedures

X and Y chromosome paints were developed from sorted yak chromosomes for sexing cattle spermatozoa. Clear hybridization signals were obtained for every spermatozoon using a modified sperm decondensation protocol and fluorescence in situ hybridization (FISH). The procedure was evaluated using the established Beltsville sperm sexing technology, which separates spermatozoa by flow cytometry into X- and Y-bearing fractions. Close agreement was found between the assessment of sperm separation by flow cytometry and by FISH with the X-Y paint set. The FISH method is a simple, reliable and robust procedure for assessing the effectiveness of separation of X and Y spermatozoa.     

Evaluation of migration models that might be used in support of regulations for food-contact plastics

Materials and articles intended to come into contact with food must be shown to be safe because they might interact with food during processing, storage and the transportation of foodstuffs. Framework Directive 89/109/EEC and its related specific Directives provide this safety basis for the protection of the consumer against inadmissible chemical contamination from food-contact materials. Recently, the European Commission charged an international group of experts to demonstrate that migration modelling can be regarded as a valid and reliable tool to calculate 'reasonable worst-case' migration rates from the most important food-contact plastics into the European Union official food simulants. The paper summarizes the main steps followed to build up and validate a migration estimation model that can be used, for a series of plastic food-contact materials and migrants, for regulatory purposes. Analytical solutions of the diffusion equation in conjunction with an 'upper limit' equation for the migrant diffusion coefficient, D_P, and the use of 'worst case' partitioning coefficients K_P,F were used in the migration model. The results obtained were then validated, at a confidence level of 95%, by comparison with the available experimental evidence. The successful accomplishment of the goals of this project is reflected by the fact that in Directive 2002/72/EC, the European Commission included the mathematical modelling as an alternative tool to determine migration rates for compliance purposes.     

The determination of soya and meat protein in raw and processed meat products by specific peptide analysis. An evaluation

The detection and measurement of characteristic peptides formed on enzymatic hydrolysis of soya protein products, meats and offals is described. Samples were heated at 120°C for 3h prior to digestion with trypsin overnight, and the resultant peptide mixtures passed through an Amicon ultrafiltration membrane. After concentration the ultrafiltrates were analysed by ion exchange chromatography on Aminex A5 resin. Peptides were detected by post-column reaction with ninhydrin. Characteristic peaks designated SP 2 and MP 1 were seen in chromatograms of digests of soya protein isolate and beef respectively, and these peaks were well resolved in beef and soya protein isolate mixtures. The SP 2 peak was shown to contain peptides derived from soya 11 S globulin. The soya protein and beef contents of a series of mixtures of freeze-dried, defatted beef and soya protein isolate were determined by measurement of the SP 2 and MP 1 peaks respectively. Soya protein content could be determined within 2% of the true value over the range 30–70% soya protein isolate and beef content could be determined within 5% of the true value in the range 20–100% beef. Analysis of five soya protein isolates, four soya protein concentrates, six soya flours and 13 textured soya products indicated considerable interproduct variation in the yield of SP 2. The MP 1 peak was seen in a range of meats, both cooked and raw. It was also present in digests of offals which contained smooth or striated muscle but not in ‘non-muscle’ offals. The protein origin of the MP 1 peak was not established but the yield appeared lower in meat products which had been heated during manufacture than in those which had received no such treatment. Analysis of a series of laboratory prepared canned and heated pork and soya protein isolate mixtures enabled the pork content to be determined to within 8% of the true value, 2% soya protein isolate could be detected but not quantified accurately.     

红肉中N-羟乙酰神经氨酸解离方法的研究进展

免疫原性的N-羟乙酰神经氨酸(N-glycolylneuraminic acid,Neu5Gc)属于致癌的高风险物质,人体中的Neu5Gc主要是通过红肉的摄入而在人体内积累,因此,N-羟乙酰神经氨酸的致癌性又将红肉的安全隐患问题推上了新的高度,探索屠宰前后Neu5Gc安全稳妥的解离方法以及解离机制势在必行。本文简要介绍了Neu5Gc的来源及其结构,通过国外学者对Neu5Gc的研究,揭示了Neu5Gc对人体潜在的致癌性危害,总结了国内外关于Neu5Gc解离方法的研究现状,并对采用分子模拟方法精准预测Neu5Gc的键解离能并获取红肉中Neu5Gc的动力学变化信息研究的可行性进行了讨论。本研究旨在为肉类研究及其生产领域探索促进非人源Neu5Gc解离的方法提供理论支撑,并充分展示其在肉类研究领域的研究价值。     

An assessment of simple referee methods for the prediction of lean in pig carcasses

A study was carried out in which carcass characteristics of 36 gilts were evaluated: 18 originated from the Hungarian 'Hungahyb' cross-breed, another 18, with undefined genetic background, from small private household plots. Two, rather simple substitute reference methods, called referee methods, were evaluated: measurement of carcass weight without skin and subcutaneous fat ('meat + bone'), and measurement of carcass weight without skin, subcutaneous fat and bone ('boneless meat'). Both methods gave a rather close relationship with the Kulmbach reference lean; however, removal of bone had presumably a beneficial effect on stability of prediction. The importance of preliminary information in quantitative form, giving a theoretical background for prediction equations, was presented as an example. Simple material balances could be formulated between reference lean and 'meat + bone' or 'boneless meat' content. Such material balances could not be set up with the indirect, rapid surrogate methods using mainly linear measurements (e.g. fat and muscle thickness, etc.) For this reason, as several other publications demonstrated, these latter methods seem to be more susceptible to bias than the referee methods. By determining the lipid content of the homogenised 'boneless meat' component, a 'lean' value adjusted to 3% fat content could be calculated from data which was compared to the dissected reference lean standardised also to contain 3% fat. These relationships, for several reasons discussed in this paper, were not as close as expected. So, further studies are needed to reveal these discrepancies.     

Advances in the industrial production of halal and kosher red meat

The worldwide volume and value of trade in halal and kosher meat and co-products are huge. Muslim countries alone consumed meat estimated to be worth USD 57.2 billion in 2008. The halal and kosher principles that govern the production of red meat have many similarities, as well as some fundamental differences. Perhaps the most significant difference is that at the time of slaughter, the animal needs only to be alive to meet the minimum halal requirement, but must be both alive and conscious for kosher. It is for this reason that reversible pre-slaughter stunning is acceptable only for halal meat, although a compromise form of post-slaughter stunning is now considered kosher in some countries. Extensive research on animal physiology and welfare has characterised and optimised the methods for stunning livestock, and enabled advancement in associated technologies. This forms the basis for harmonising the religious and secular requirements for the protection of animal welfare at slaughter. These technologies and the associated processing practices for the industrial production of halal and kosher meat are reviewed in this paper.     

肉制品中亚硝酸盐的测量不确定度评定

目的 对分光光度法测定肉制品中亚硝酸盐的含量进行测量不确定度评定.方法 根据分光光度法测定亚硝酸盐的检测步骤建立测量不确定度模型,分析影响测定结果的各个分量,最后计算得到合成不确定度.结果 肉制品中亚硝酸盐含量的扩展不确定度为(2.71±0.16)mg/kg(k=2).结论 标准曲线拟合、试液显色、样品重复测量以及标准...     

Extended shelf life milk processing: Effect of simulated cleaning in place on the germination and attachment of Bacillus cereus spores

The effect of simulated cleaning in place (CIP) was determined on the structure, attachment and growth of Bacillus cereus spores isolated from raw milk and biofilms in filler nozzles from extended shelf life (ESL) milk processing lines. Simulated CIP treatment structurally affected >98% of B. cereus spores, while 0.1% remained intact. Following simulated CIP treatment, B. cereus spores were able to attach to stainless steel coupons and form biofilms. B. cereus spores were capable of germination and growth under refrigerated conditions for more than 28 days. Contamination with B. cereus spores may lead to a reduced shelf life and potentially be a safety risk in ESL milk with a prolonged shelf life.     

Characterisation and antimicrobial activity of active polypropylene films containing oregano essential oil and Allium extract to be used in packaging for meat products

Cooked ham is more prone to spoilage than other meat products, making preservation a key step in its commercialisation. One of the most promising preservation strategies is the use of active packaging. Oregano essential oil (OEO) and Proallium® (an Allium extract) have previously been shown to be useful in polylactic acid (PLA)-active films for ready-to-eat salads. The present work aims to study the suitability of polypropylene (PP) films containing OEO and Proallium® in the preservation of cooked ham. Concerning the technological features of the studied material, no significant changes in the mechanical or optical properties of PP films containing the active substances were recorded in comparison to the PP film without extracts. However, films containing both active substances were more flexible than the control film and less strong, highlighting the plasticisation effect of the natural extracts. Moreover, physical properties changed when active substances were added to the film. Incorporation of 4% Proallium® affected the transparency of the film to a higher extent compared to 8% OEO, undergoing decreases in transparency of 40% and 45%, respectively. Moreover, only the film containing the highest amount of OEO (8%) significantly decreased the thickness. Both active substances showed antibacterial properties; however, Proallium®-active films seemed to be more effective against Brochothrix thermosphacta than PP films containing OEO, with all percentages of Proallium® killing the bacterial population present in the ham after 60 days. In addition, materials containing the lowest Proallium® content exhibited higher acceptability by consumers in the sensory analyses with 63–100% willing to purchase, better even than the control package (56–89%). In fact, 2% of Proallium® obtained the best results in the odour study performed by the panellists.