News

Differentiating gelatin species is an analytical challenge because of a lack of intact DNA.  Most speciation methods therefore target the profile of proteins.  Proteins are difficult to analyse - they are too large to measure directly by techniques such as LC-MS, without  prior breaking down, and their folded structure is also an important diagnostic parameter.  This structure is disrupted by many of the sampling and extraction procedures used in analytical method. Analysis of mixed gelatins is particularly difficult.

This method (open access) used a new approach based on the interaction of ethanol with amino acids inside a protein. Ethanol can denature globular proteins by disrupting intraprotein hydrogen bonds due to hydrophobic interactions. However, when added to solutions having proteins with considerable number of α-helices, ethanol can stabilize the protein structure and prevent aggregation. The specific effects of ethanol on protein structure and function can vary depending on the protein's composition and environment.

Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy was used to leverage ethanol's differential effects on gelatin's amide bands for quantifying pork gelatin contamination in bovine gelatin.

The authors report that the method showed a strong linear correlation between contamination levels and amide band transmission, with detection and quantification limits of 0.85 and 2.85 mg/100 mg (pork in bovine), respectively. It effectively identified pork gelatin in halal candy, with recovery rates from 50.05 % to 103.69 %.

Russian scientists have developed a rapid test for chicken and pork in processed meat products, which takes 33 minutes to complete and can be done in-situ without the need of laboratory equipment. The test consists of a 3 min of crude DNA extraction, 20 min of recombinase polymerase amplification (RPA) at 39 °C, and 10 min of lateral flow assay (LFA) detection. The RPA–LFA assay is based on designed fluorescein and biotin-labelled primers developed from the cytochrome B gene, which can identify as little as 0.001% w/w  of the target meat component. The assay was tested on  processed meat products and to meat after heating, and the results were confirmed by real-time PCR.

You can read the full open access paper here

Chinese researchers have applied an electronic nose (E-nose) system to detect beef adulteration with pork. The E-nose system uses a colourimetric sensors, which give different colours with different volatile compounds emmitted by the meat, the resulting coloured pattern is analysed by image analysis before and after exposure to the meat sample. The resulting signals are then analysed chemometrically to predict both qualitatively and quantitatively, the adulteration of beef with pork. This system was tested using samples of raw minced beef and pork mixed at different levels from 0%  to 100%  adulteration at 20%  increments. The system was able to accurately identify adulteration and give good quantitative correlation.  Read the article and the full paper.

This study evaluated the application of relative quantification of unique heat-stable species specific peptides in highly processed meat proteins. Using nano-LC-QTOF-MS/MS, 20 new, heat-stable peptide markers unique to chicken, duck and goose were identified. The method enabled detection of 1% (w/w) of chicken and 1% (w/w) pork in a mixture of the meat of three species, as well as 0.8% (w/w) beef proteins in commercial poultry frankfurters. This method includes a correction factor for each protein, based on the peptide MS detection probabilities, which are influenced by the physicochemical properties of the peptide. Considerable differences in abundance of myofibrillar and sarcoplasmic proteins were observed between samples and illegal proportions of ingredients were discovered.

Read the abstract at: Meat species quantification using peptide markers

As part of the Defra Project FA0159 on production and geographical origin of food, Fera are conducting a survey on the need for and availability of pork data bases for geographical origin determination.  Anyone who is interested in the country of origin labelling of pork should complete the survey. The results will be collated and incorporated into the final Defra project report which will be made publicly available at the end of 2018.

IFR has developed a rapid multiple reaction monitoring mass spectrometry method for the detection and relative quantitation of the adulteration of meat with that of an undeclared species is presented. Selected peptide markers derived from myoglobin can be used for species detection, and the ratios of  transition peak areas for corresponding peptides is proposed for relative quantitation. The method has been developed from the myoglobin of four meat species - beef, pork, horse and lamb, and test results are encouraging.

Read the full research paper at: http://pubs.acs.org/doi/10.1021/acs.analchem.5b02318                                                

or read a summary article at: http://www.foodqualitynews.com/R-D/Researchers-target-myoglobin-protein-to-stop-food-fraud

A lab-on-a-chip-based multiplex polymerase chain reaction (PCR) assay for the authentication of five non-halal meat species in foods is described. Using species-specific primers, 172, 163, 141, 129 and 108-bp sites of mitochondrial ND5, ATPase 6 andcytochrome b genes were amplified to detect cat, dog, pig, monkey and rat species under complex matrices. Species-specificity was authenticated against 20 different species with the potential to be used in food. The assay was optimised under the backgrounds of various commercial meat products and validated for the analysis of meatballs, burgers and frankfurters, which are popular fast food items across the globe. The assay was tested to detect 0.1% suspected meats under commercial backgrounds of marketed foods.

Read more in Food Additives and Contaminants at: http://www.tandfonline.com/doi/abs/10.1080/19440049.2015.1087060