Want to keep learning?

This content is taken from the Queen's University Belfast's online course, Tackling Global Food Safety. Join the course to learn more.

Skip to 0 minutes and 1 secondThere are two types of detection systems, random and targeted.

Skip to 0 minutes and 11 secondsRandom sampling.

Skip to 0 minutes and 14 secondsSamples are taken randomly by inspectors for testing. There is no intelligence to suggest any problems with this food type exist.

Skip to 0 minutes and 26 secondsTargeted sampling.

Skip to 0 minutes and 28 secondsWhen there is intelligence about a particular food type or adulteration, samples which are at highest risk are taken for testing.

Skip to 0 minutes and 40 secondsSubstitution fraud.

Skip to 0 minutes and 45 secondsAs we said earlier, the 2008 Chinese milk scandal involved milk in infant formula and other food materials and components adulterated with melamine.

Skip to 0 minutes and 58 secondsWhy did this happen?

Skip to 1 minute and 1 secondMilk prices are dictated by protein content. This was measured by the amount of nitrogen present, using the Kjeldahl method.

Skip to 1 minute and 12 secondsMelamine has a very high nitrogen content and was added to milk to make it appear to have high protein levels.

Skip to 1 minute and 21 secondsHow is melamine detected?

Skip to 1 minute and 25 secondsThere are three key ways to detecting melamine.

Skip to 1 minute and 30 secondsImmunoassay based methods. Immunoassay based techniques are based on the production of specific antibodies to melamine and the incorporation in to a rapid screening test.

Skip to 1 minute and 42 secondsChromatography methods. Chromatography methods are based on separation using properties of solubility, charge, et cetera, then detected by UV absorption or using mass spectrometry.

Skip to 1 minute and 56 secondsSpectroscopic techniques. Production of spectroscopic fingerprints using Near Infrared/Raman techniques.

Skip to 2 minutes and 8 secondsRice fraud.

Skip to 2 minutes and 12 secondsAnother example of substitution fraud is basmati rice fraud.

Skip to 2 minutes and 19 secondsBasmati rice is considered a better quality rice than alternatives, such as patna. However, basmati rice fraud is where the rice product is substituted or adulterated with poor quality rice grains.

Skip to 2 minutes and 35 secondsTo detect this type of fraud, DNA based methods, PCR, were developed to differentiate between different rice strains.

Skip to 2 minutes and 46 secondsThrough these methods, low-level adulteration of basmati rice can be detected.

Skip to 2 minutes and 54 secondsOther examples of substitution include virgin olive oil and tuna.

Skip to 3 minutes and 2 secondsVirgin olive oils are obtained from the olive using only mechanical means that do not alter the oil in any way.

Skip to 3 minutes and 11 secondsThe oil has not undergone any treatment other than washing, decanting, centrifuging, and filtering.

Skip to 3 minutes and 20 secondsThe definition "virgin" excludes oils obtained by the use of solvents, deodorisation, or other refining techniques.

Skip to 3 minutes and 31 secondsThe definitions "extra virgin" and "virgin" are based on a European marketing standard that includes fatty acid content and organoleptic characteristics.

Skip to 3 minutes and 43 secondsThe oil can also have a designation of origin, where it meets the specific characteristics associated with a region.

Skip to 3 minutes and 53 secondsRefined olive oil is an oil of lower quality, obtained by refining methods that remove excess acidity.

Skip to 4 minutes and 3 secondsOlive oil is a low cost blend, consisting mostly of refined olive oil and a small amount of virgin olive oil.

Skip to 4 minutes and 13 secondsThere are several different closely related members of the tuna family, including albacore, yellowfin, and skipjack.

Skip to 4 minutes and 23 secondsThey can be sold as canned products or as fresh fish.

Skip to 4 minutes and 29 secondsThere are premium varieties of tuna, such as the northern bluefin and southern bluefin tunas, which are prized for their size, texture, colour, fat content, and taste and fetch high prices on the Japanese market.

Skip to 4 minutes and 46 secondsHowever, the majority of canned tuna is made up of the more common varieties, such as yellowfin and skipjack.

Skip to 4 minutes and 54 secondsIn the same family, there are many other species of fish, classed as bonito, which fetch a much lower price when canned.

Skip to 5 minutes and 3 secondsSubstitution of tuna by bonito in canned products has proved a problem in the past.

Skip to 5 minutes and 12 secondsSudan dyes are synthetically produced red dyes. Their degradation products are considered to be carcinogens, and teratogens.

Skip to 5 minutes and 23 secondsDue to this fact, the EU does not permit the use of these colours as food additives.

Skip to 5 minutes and 31 secondsHowever, in some countries these dyes are still occasionally used, in order to intensify the colour of bell pepper and chilli powder.

Skip to 5 minutes and 42 secondsIn February, 2005, Great Britain experienced an extensive rapid alert action.

Skip to 5 minutes and 51 secondsDue to the widespread use of Sudan-contaminated chilli powder, different products, like Wuster sauce, pizza, pot noodles, and seafood sauces, were subjected to complete recalls.

Skip to 6 minutes and 6 secondsHow you detect the Sudan Red adulteration?

Skip to 6 minutes and 12 secondsIt's the same techniques that were used in the melamine case, immunoassays, chromatography, spectroscopic fingerprinting.

Skip to 6 minutes and 24 secondsThere are two main ways in the European Union where you can classify the geographic origin of food products, the Protected Designation of Origin, PDO and the Protected Geographical Indication, PGI.

Skip to 6 minutes and 49 secondsPDO, or Protected Designation of Origin, guarantees products such as Stilton cheese, which must be produced, processed, and prepared within their original geographic area, using traditional methods.

Skip to 7 minutes and 7 secondsPGI, or Protected Geographical Indication, protects products such as Cornish pasties, which are linked to a geographical area where at least one stage of the production, processing, or preparation must take place.

Skip to 7 minutes and 25 secondsAn example of geographic food fraud is beef.

Skip to 7 minutes and 31 secondsBrazilian sirloin beef costs about £4.50 GBP per kilo. Whereas British sirloin beef costs about £8.50 GBP per kilo. The DNA testing at 40 food outlets in 2008 revealed 20% percent of samples taken from beef labelled as British in the Southwest of England were foreign.

Skip to 7 minutes and 59 secondsEight of the samples had the DNA of cattle that only exist in South America and Africa.

Skip to 8 minutes and 8 secondsSo how do you detect geographic fraud?

Skip to 8 minutes and 14 secondsThe main technique used is isotope ratio mass spectrometry.


As there are a huge number of ways that food fraud can be perpetrated it seems logical that quite a different range of scientific techniques have been developed to detect the fraud.

These range from simple microscope based methods, to look for types of pollen in honey, to more complex DNA techniques that identify the species of a food sample. However in some types of food there is little or no DNA present, for example in oils, thus other methods are needed. These often look at identifying components such as sterols or fatty acids of a particular type of oil that can identify them as being different from other lower quality oils.

The most widely used method to identify the geographic origin of foods is based on Isotope Ratio Mass Spectrometry (IRMS). This technique can measure a wide range of isotopes of elements such as hydrogen, oxygen, carbon and nitrogen. These signatures can be linked with soil types and water supplies of specific geographic regions. Wine, which is very often associated with geographic fraud has probably the largest IRMS isotope signature database in the world.

The use of molecular fingerprinting technologies are now been widely researched as new tools in the fight to detect food fraud. These procedures also referred to as ‘untargeted analysis’ which will become more and more popular as methods are developed, and the technology platforms used to produce the fingerprints become cheaper and more portable.

This video will illustrate some examples of food fraud and outline the various techniques used to detect them.

Share this video:

This video is from the free online course:

Tackling Global Food Safety

Queen's University Belfast