Meat test: Llama burger, anyone?

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  • Published: Mar 15, 2013
  • Author: David Bradley
  • Channels: Chemometrics & Informatics
thumbnail image: Meat test: Llama burger, anyone?

Carnal knowledge

Which is better llama or horse? There's only one way to find out!!! No. Not a fight...transflectance NIRS Photo by David Bradley

Partial least-squares regression of data from visible and near infrared reflectance spectroscopy (VIS-NIRS) can be used to quickly discriminate between beef, horse and llama meat in processed food products.

The adulteration of meat products identified as containing only beef and yet testing positive for horse and even other animals is headline news in Europe at the moment, but such illicit blending of food with cheaper meat is nothing new. In Chile, the problem of horse being added to beef products is well known, but the issue of whether there is llama in one's burger is of growing concern. Now, L.W. Mamani-Linares, C. Gallo and D. Alomar of the Universidad Austral de Chile, in Valdivia, Chile, have developed a cheminformatics solution that allows them to extract the requisite data to quickly identify such adulteration.

On reflection, it's definitely meat

The researchers point out that quality and origin are important issues not only to consumers but to food regulators around the world. As consumers have become more aware of health and safety issues, so demand for clearer labelling and perhaps more importantly guarantees that allow them to trust what retailers are selling have increased in the last decade. Food scares that reach the tabloids and shock and worry the public seem to occur with increasing frequency, but inevitably the ways and means to address such problems lies with improved analytical procedures. Simpler techniques for testing without the need to resorting to biotechnological approaches would be quicker, cheaper and easier to implement at all levels from food supplier, to processor and on to retailer or restaurateur, with regulators able to test at any point in the supply chain in a much more timely manner too.

It is relatively easy to adulterate ground, or minced, beef used in burgers and various other convenience foods. The process of mincing the meat removes the possibility of a simple visual test because muscle forms are pulverised beyond recognition, while flavourings and other additives can be used to cheaply mask any odd flavours from say the addition of horse to a beef ready-meal. There are numerous technologies used to test meat products including DNA tests, immunological approaches, enzymatic assays, none of which are particularly simple to implement nor offer a rapid response. They all require sophisticated sample preparation too. By contrast, the team suggests, Near infrared spectroscopy (NIRS) is an attractive alternative that is both fast, non-destructive and requires only a small unprocessed sample for testing. Perhaps the only problematic issue is that NIRS generates complex spectra with several overlapping peaks.

Non-destructive testing

Nevertheless, NIRS has already been used in the food industry for quality analysis and quality control (QA/QC) and so is already a familiar tool at various stages of processing and regulation. Various research teams have successfully applied NIRS techniques to the discrimination between different types of minced beef samples. They have been able to identify breed and to distinguish between samples that have previously been frozen and thawed, for instance. The team at Valdivia have now demonstrated that it is possible to discriminate between juices from meat products containing beef, horse and llama using NIRS. Their success hinges on a Cheminformatics approach to disentangling the various overlapping bands in the spectra. The use of meat juices makes the process even simpler because it avoids the need to carry out even a bare-bones sample preparation.

The team tested their approach on meat samples (Longissimus lumborum) from beef, llama and horse purchased from different local butcher shops and supermarkets in Valdivia and nearby Temuco, while the llama meat was shipped from butcher shops in Arica. Reflectance was used for testing minced meat samples whereas transflectance could be used to analyse samples of meat juice from the various products. "The use of transflectance to collect meat juice spectra is a sound method, as it allowed slightly better identification results for llama and horse samples," the team says.

They add that broadening the calibration set with extra samples of different ages, geographic origin, animal breeds, production systems and different muscle tissues could be used to improve the accuracy of this food testing approach still further and to make the cheminformatics more robust still. "We have also published research where the jerky from the same species could be successfully identified, Alomar told SpectroscopNOW [Vet. Méx., vol 43, 133-141].

Related Links

Meat Sci 90, 378-385: Identification of cattle, llama and horse meat by near infrared reflectance or transflectance spectroscopy

Article by David Bradley

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

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