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The addition of cheaper offal (brain, large intestine, liver, heart and kidney) is difficult to discern in minced beef, although there are ELISA methods for some offal tissues detailed on this website. This research paper details the first use of rapid evaporative ionisation mass spectrometry (REIMS) to eliminate sample preparation and provide near-instantaneous results of the presence of offal in minced beef. REIMS was applied with chemometric analysis to give unique or significant markers of beef brain, heart, kidney, large intestine and liver tissues permitting detection and identification in beef mince. The adulteration levels detected with the REIMS technology when analysing raw adulterated beef burgers were; brain (5%); heart (1–10%); kidney (1–5%); large intestine (1–10%) and liver (5–10%). For boiled adulterated samples; brain (5–10%); heart (1–10%); kidney (1–5%); large intestine (1–10%) and liver (5–10%). 

 Read the full paper here

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  • Perhaps I could add to this discussion. I fully agree that ‘old fashioned methods’ should still play a role in the analysis of food, if appropriate. From my understanding, histological assays were used historically to detect offal in the UK, but failed (a) to provide quantitative data for offal levels and (b) species identification of the specific offals (a requirement of the labelling laws). In addition, histological assays could not always detect offal in highly processed products (eg canned materials). As a consequence, FSA felt there was a need to establish an improved method for offal detection, and put out a call for new proteomic-based methods in 2006. Nottingham Trent University was subsequently commissioned to develop these assays for various offals in processed samples. Our assays were considered to be ‘fit for purpose’ by Defra’s Authenticity Methods Working Group and used in a pilot study which was published recently. This pilot study also included assays for added serum and was published as part of another project (FAO122*). Our immunoassays are based on the Western blotting technique (not ELISA) and can be combined with peptide mass fingerprinting to provide both quantification and species identification. I agree that these methods are perhaps more technically demanding than histological assays, but they are robust and reliable, and I would argue that they also have an important role in detecting undeclared offal type and species in meat products.

    *http://sciencesearch.defra.gov.uk/Document.aspx?Document=14312_Fina... – Chapter 3B

    Best wishes

    Ellen Billett

    http://sciencesearch.defra.gov.uk/Document.aspx?Document=14312_FinalReportFA0122.pdf
  • Thank you for your offer. The protocol for the detection of offal is easy: a normal HE (haematoxylin-eosin) stain is used. In our lab we just produce cryosections directly from the (not pretreated) sample, e.g. we make section (approx. 10 micrometers thin) from a piece of frozen sausage  or frozen ball of minced meat. Actually you can't do any wrong! I will send you my staining protocoll for I don#t know if it differs a lot from pathological HE-staining protocolls.

    Best regards, Tanja

  •  Dear Tanja, 

    Thank you for a very comprehensive discussion about histological analysis of mince etc for offal. I totally agree that sometimes we overlook the simplest and cheapest method for authenticity testing if they are successful, in our quest for more and more sophisticated approaches. Microscopy was common place in our control labs many years ago, but sadly not used that routinely today. I wondered whether you would be willing to share any histology protocols for offal detection with the Network (even if we need to get them translated). My email is mwoolfevfan@gmail.com. 

    Kind regards

    Mark

    Mark

  • Dear Mark,

    in minced meat it should be quite easy to detect different offals because the muscle fibers are not completely destroyed like in boiled sausage, e.g. frankfurters so that the microstructure of tissues can be analysed very well. The cooking of a product is no problem for the histological analysis, e.g. in cooked hamburger patties offals could easily be found. This is an enourmous advantage over ELISA, because with food histology it is possible to detect offals (and other foreign proteins of animal an vegetal sources) even in highly processed meat pruducts like canned and sterilized meat or sausage. You are right that the "classical" histology is rather qaulitative than quantitative, but if you know how much of an offal is "normal" (we say "technologically not avoidable") you get an idea if the found amount is more than normal. And espacially in minced meat there should be no offals at all because according to (EG) Nr. 853/2004 Annex III, Section V, Chapter II,  Nr. 1 a and b) minced meat must comply with the requirements for fresh meat and must derive from skeletal muscle, including adherent fatty tissues (and usual amounts of connective tissue). But nethertheless food histology may even produce quantitative results by point counting techique or phase-analysis via digital microscopy. Apart from that, the meat industry (and especially the side product industry) gets smarter: proteins extracted from offals and blood are checked by the producers on DNA-remainings so that they produce DNA-free amino acids and hydrolysates only. At the moment food histology is the only reliable analysis I know that is able to detect even gelatine (even in frakfurters!), blood plasma (used from the same species as the meat for the sausage originates from - of course!), hemoglobin and many other foreign proteins of animal origin. In Germany we have a long tradition of food histology but I know that food authorities in other countries do this surveys, too e.g. France, Czech Republik and The Netherlands. Without minimizing the success of new analyses, I just want to point out to people and scientists that sometimes "old-fashioned" methods are at least the same or even better than new ones and you should not forget about them only because the are not so hip! Long live histology :-)

    Best regards, Tanja

  • Tanja,

    You are probably right that histology will be able to detect different offal tissues in raw mincemeat. I suspect it will depend on the degree of fine mincing and whether there is more than one type of offal tissue present. However, this will only be qualitative rather than quantitative. I doubt whether the histology method will be reliable in processed meat products especially cooked products. ELISA methods have been developed for some offal tissues in the UK's Food Authenticity Programme and you can find the reports (e.g. FA0106)  in the research section of the website, which can be widely used and much cheaper than using a high resolution mass spectrometer.

    Reards

    Mark Woolfe

  • Did anyone think of food histology? It is very easy to detect all those offals in minced meat by histology - with even lower detection limits. A simple, easy, unexpensive and accredited method!

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