Rapid method for the determination of meat in food products

A method for the determination of meat in food products is described based on the determination of protein-bound 3-methylhistidine. The method involved high pressure liquid chromatography and reduced the elution time of previous methods from 7 h to 10 min. The accuracy of the method was increased by using electronic integration. The method was used to determine the meat content of nine meat pies and three hamburger patties.     

Simple and rapid microbiological method for determination of residual antibacterials in meat

A simple and rapid screening method using bioassay for the simultaneous analysis of antibacterials (penicillins, cephalosporins, macrolides, tetracyclines, quinolones, etc.) in meat has been developed. A 5 g sample was homogenized with 5 mL of methanol, and the homogenate was centrifuged for 10 min with 3,000 rpm. The pulp disk method with Bacillus subtilis BGA (Antibiotic Medium 5 (pH 8) and 8 (pH 6)), Micrococcus luteus ATCC 9341 and Geobacillus stearothermophilus as test organisms was employed for the assay of the antibacterials. Typical antibacterials (penicillin G, ampicillin, cefapirin, cefalexin, erythromycin, spiramycin, oxytetracycline, chlortetracycline, streptomycin, dihydrostreptomycin, enrofloxacin and oxolinic acid) were detected at levels of ca. 0.005-2.5 microg/g in meat. Therefore, we recommend this proposed screening method for routine analysis of residual antibacterials in livestock products.     

Microwave dielectric spectroscopy for the determination of pork meat quality

The use of dielectric spectra to detect quality defects in porcine muscle during postmortem period was evaluated. The changes in dielectric spectra during meat ageing were also studied. For these purposes, dielectric spectra were measured by using an Agilent 85070E Open-ended Coaxial Probe connected to an Agilent E8362B Vector Network Analyzer from 500 MHz to 20 GHz parallel and perpendicular to muscle fiber direction. This study reveals that dielectric properties at two punctual frequencies (0.5 GHz and 10 GHz) are a useful tool to determine meat quality classes (RFN, PSE, and DFD) soon (6 h) after slaughter. Based on these results, it is possible to develop control algorithms in order to discriminate low quality pork meats and to decide their best uses. Moreover, the evolution of dielectric spectra during meat ageing showed important variations only in DFD meats, while in PSE and RFN meats the variations were observed only at some punctual frequencies of the spectrum during the 24 h after slaughter.     

Automated turbidimetry for rapid determination of the bacteriological quality of raw meat and processed meat products

A fully automated centrifugal spectrophotometer for turbidimetric measurements linked to a computer for data processing was used to record and analyze growth of different types of bacteria associated with spoilage of raw meat and processed meat products (sliced meat for sandwiches) in order to predict bacterial counts. Media for this specific analysis were developed to enumerate total viable count, lactic acid bacteria. Brochothrix thermosphacta and Pseudomonas spp. Correlation coefficients of -0.91 to -0.97 were obtained between the conventional plate count technique and the turbidimetric method (linear regression). Lactic acid bacteria in the range 10(3) to 10(9) cfu/g could be detected within 48 h, whereas total viable count, Brochothrix thermosphacta and Pseudomonas spp. generally could be detected within 24 h. Counts exceeding 10(7) cfu/g could be detected within 6 h.     

Rapid determination of residues of 4 tetracyclines in meat by a microbiological screening, HPLC and LC/MS/MS

A rapid and precise determination residues of 4 tetracyclines (TCs) (oxytetracycline (OTC), tetracycline (TC), chlortetracycline (CTC) and doxycycline (DOXY)) in meat was developed by employing three analyses; a microbiological screening, HPLC and LC/MS/MS. TCs were extracted with pH 4.0 McIlvaine buffer containing 0.01 mol/L EDTA from a meat sample, and then purified using a mixed mode, reversed-phase and cation-exchange cartridge. The mean recoveries (n=5) of 0.2 microg/g OTC, TC and CTC, 0.05 microg/g DOXY spiked in meat samples were 76.6-99.0% (C.V. 1.6-5.4%). In 13 meat samples in which the microbiological screening indicated the presence of TCs, CTC (9 samples) and DOXY (4 samples) were identified with HPLC and LC/MS/MS.     

Comparison of a microbiological and a spectrophotometric method for the determination of nicotinic acid in fresh meat

The microbiological method for the determination of nicotinic acid with the aid of Leuconostoc mesenteroides ATCC 9135 was compared with a spectrophotometric method which included cleaning-up of a meat extract by thin-layer chromatography. The results obtained were in good agreement. Average recovery factors of 95–107% and reproducibilities of 2–6% (standard deviation in % of the average) indicate that the results are reliable.     

肉品质量无损检测技术研究进展

肉类和肉类食品品质与安全检测一直是肉类行业中关注的热点。本文综述了超声波、电磁特性、电子鼻与电子舌、计算机视觉、光谱分析等几种当前主要无损检测技术在肉品质量评价中的研究进展。其中,重点介绍了光谱分析中具有图谱合一、可同时获取样品内外部品质信息特性的高光谱成像技术及其在国内外肉品品质检测中的应用现状,提出了该技术在肉类品质检测研究方向的几点思考,并展望了无损检测技术在肉品品质检测中的研究前景,以期为后续研究提供参考。     

Factorial interlaboratory tests for microbiological measurement methods

This paper presents a validation approach for microbiological methods based on a combination of interlaboratory tests and factorial experiments. It requires not more than 4 participants but is achieving comparable statistical confidence as in method validation studies with 8–12 participants, if properly designed. The approach is illustrated by a comprehensive validation of the Arxula adeninivorans yeast estrogen screen (A-YES) assay for the detection of estrogenic activity in mineral water.     

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.     

Turbidimetric measurement as a rapid method for the determination of the bacteriological quality of minced meat

A prototype rapid automated turbidimetric apparatus was used to record the growth of pure cultures of Escherichia coli, Staphylococcus aureus and Streptococcus faecalis to evaluate instrument performance. The turbidimetric measurements were applied in experiments concerned with the determination of the bacteriological quality of fresh minced meat in terms of total counts. As a method of automated routine examinations of minced meat, it showed great promise. A correlation coefficient of 0.98 was established between the conventional plate count method and the turbidimetric method. Samples could be processed within 24 h.     

Rapid determination of the 3-methylhistidine content of meat using 1-fluoro-2,4-dinitrobenzene

The protein-bound 3-methylhistidine content of meat species has been shown to be of value in predicting the meat content of food products. The present paper deals with the development of a rapid method for the detection and estimation of the dinitrophenyl (DNP) derivatives of the methylamino acids and dipeptides, and in particular 3-methylhistidine. The DNP derivatives of methylated and non-methylated basic amino acids and dipeptides were shown to have differing solubilities in diethyl ether and aqueous solution. These differences allowed preliminary purification of hydrolysed meat extracts, thereby allowing rapid determination of 3-methylhistidine using a short ion-exchange resin column.     

Development of a dielectric spectroscopy technique for the determination of key biochemical markers of meat quality

Dielectric measurements of different standard solutions (nucleotides, nucleosides, lactic acid and myoglobin) were assayed simulating the concentrations of these substances in early postmortem meat. These assays were performed for considering the potential use of dielectric spectra for the quality control of meat. Good correlations among solutions of Adenosine Triphosphate (ATP), Inosine Monophosphate (IMP) and lactic acid with loss factor at punctual frequencies (0.5, 0.915 and 1 GHz) were found. The other assayed substances did not present a marked effect over the electromagnetic spectra. Good correlations of dielectric properties with IMP and lactic acid content of real pork meat samples were also found at 0.5 GHz. This work is presenting prospective data of dielectric spectra for certain key biochemical markers in order to consider its potential application as a non-destructive control sensor for the prediction of pork meat quality.     

A microbiological screening method for the indication of irradiation of frozen poultry meat

A microbiological screening method for the detection of irradiation of frozen poultry meat was developed on the basis of the combined use of total cell count by the direct epifluorescent filter technique (DEFT) and viable cell count by the aerobic plate count method (APC). Samples of ground, deboned poultry leg were irradiated or not with dose levels of 3, 5 and 7 kGy using an electron beam accelerator. All samples were frozen before the irradiation treatment. The average values of the differences between DEFT and APC counts in control samples and those irradiated with doses of 3, 5 and 7 kGy were 1.14 log units for control samples, and 3.16, 3.68 and 3.79 log units for the irradiated samples. A difference of at least 2 log units can therefore be considered as a limit value indicating probable irradiation treatment necessitating further investigations.

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Anwendung eines mikrobiologischen Unterscheidungsverfahrens zum Nachweis der Bestrahlung von gefrorenem Hühnerfleisch

Zusammenfassung Es wurde ein mikrobiologisches Verfahren zum Nachweis der Bestrahlung von tiefgefrorenem Hühnerfleisch auf der Basis kombinierten Einsatzes direkter Epifluoreszenzfiltertechnik (DEFT) und Kolonieauszählung (APC) entwickelt. Die Proben - knochenfreie, zerkleinerte Hühnerschenkel - waren entweder unbestrahlt oder mit einem Elektronenbeschleuninger mit Dosen von 3, 5 bzw. 7 kGy bestrahlt worden. Alle Proben waren vor der Bestrahlung eingefroren worden. Die Mittelwerte der Differenzen zwischen den DEFT- und den APC-Ergebnissen betrugen bei den unbestrahlten Proben 1,14 logarithmische Einheiten und bei den mit 3, 5 bzw. 7 kGy bestrahlten Proben 3,16, 3,68 bzw. 3,79 logarithmische Einheiten. Die Differenz von wenigstens zwei logarithmischen Einheiten kann als Grenze für die Möglichkeit eines Nachweises eventueller Bestrahlung betrachtet werden und macht weitere Untersuchungen erforderlich.

     

Effects of modified atmosphere packaging (MAP) on the microbiological quality and shelf life of ostrich meat

Effects of various concentrations of O₂/CO₂ in modified atmosphere packaging on the microbiological quality and shelf-life of ostrich meat was investigated. Nine–12 months old ostriches were used. The iliofibularis muscle was cut into small cubes that were divided into five groups and then separately packaged under various gas mixes: air and O₂:CO₂:N₂ ratios of 80:20:0, 60:20:20, 60:40:0, and 40:40:20, using 2 different headspace ratios (1:1 and 3:1). The packaged meats were kept at 4 °C for 10 days and were analysed microbiologically, physico-chemically and sensorially. As a result, the meat quality and shelf-life of ostrich meat under various gas compositions were improved; microbial growth was delayed due to high CO₂ usage and shelf-life was increased by 5–7 days. However, an undesired loss of red colour of the ostrich meat may affect consumer acceptance.     

Sampling methods for microbiological analysis of red meat and poultry carcasses

Microbiological analysis of carcasses at slaughterhouses is required in the European Union for evaluating the hygienic performance of carcass production processes as required for effective hazard analysis critical control point implementation. The European Union microbial performance standards refer exclusively to the excision method, even though swabbing using the wet/dry technique is also permitted when correlation between both destructive and nondestructive methods can be established. For practical and economic reasons, the swab technique is the most extensively used carcass surface-sampling method. The main characteristics, advantages, and limitations of the common excision and swabbing methods are described here.     

Evaluation of the microbiological status of raw pork meat in Korea: modification of the microbial guideline levels for meat

Food Science and Biotechnology - This study aimed to evaluate the suitability of total aerobic plate count (APC) guidelines for raw pork (< 1 × 107 CFU/g)...     

Application of the direct epifluorescent filter technique as a rapid method in microbiological quality assurance in the meat industry

The direct epifluorescent filter technique (DEFT) and the standard plate count (SPC) were compared in the examination of raw and heat-treated meat products. The most promising results were obtained with raw ground beef, where good agreement was found between DEFT and the SPC. These products had bacterial counts of 10⁵/g and above; the correlation coefficient was 0.79. For heat-treated meat prooducts, good agreement between DEFT and SPC was found for products with high counts at the end of shelf life (10⁸/g), whereas very poor agreement was found in products with low counts. Nevertheless, useful information with DEFT was also found in these cases, since it was possible to estimate approximately the number of bacteria present before heat treatment. The study clearly showed that DEFT could not distinguish between live and dead cells, and also that this was not a prerequisite for using DEFT. It was concluded that DEFT could be used with advantage in a meat quality assurance programme for ground beef to check that a microbiological specification of 10⁶/g was adhered to. However, automatic counting could not be used at this level. This limits the capacity to 20 samples per person per day. It is hoped that further development of the DEFT system will overcome this problem.     

Rapid determination of pork sensory quality using Raman spectroscopy

Existing objective methods to predict sensory attributes of pork in general do not yield satisfactory correlation to panel evaluations, and their applications in meat industry are limited. In this study, a Raman spectroscopic method was developed to evaluate and predict tenderness, juiciness and chewiness of fresh, uncooked pork loins from 169 pigs. Partial Least Square Regression models were developed based on Raman spectroscopic characteristics of the pork loins to predict the values of the sensory attributes. Furthermore, binary barcodes were created based on spectroscopic characteristics of the pork loins, and subjected to multivariate statistical discriminant analysis (i.e., Support Vector Machine) to differentiate and classify pork loins into quality grades ("good" and "bad" in terms of tenderness and chewiness). Good agreement (>83% correct predictions) with sensory panel results was obtained. The method developed in this report has the potential to become a rapid objective assay for tenderness and chewiness of pork products that may find practical applications in pork industry.     

催化动力学光度法快速测定卤肉制品中的痕量铬

目的 研究用催化动力学光度法快速测定卤肉制品中痕量铬所需的最佳条件。方法 以卤肉制品为样品,通过单因素实验建立Cr(Ⅵ)-H2O2-溴甲酚绿催化反应体系, 据此测定卤肉制品中的铬含量。结果 最佳试验条件为: 测定波长630 nm, pH4.4, 0.2 mL30%过氧化氢, 0.4 mL1 g/L溴甲酚绿, 60 ℃水浴加热5 min。该方法测定铬的检出限为0.256μg/mL, 相对标准偏差小于0.12（n=5）, 回收率为88.5%~106%。结论 与国标中方法相比, 该方法操作简单, 所用仪器价廉易得, 成本花费较少, 易于推广。