Food Authenticity Membership Category; please pick a category that best describes your profession:
Food industry/production
Additional information about your food authenticity interests
I am the QC supervisor at a dried fruit manufacturer. I am specifically interested in ensuring that none of our raw materials are adulterated.
Comments
Hi Marli
As you have found out already this is a very complex area. It is often difficult/impossible to show that there is nothing added to a product or at least it is toooooo expensive!! However, it is often easier to show that a product contains something that would not be expected in a particular fruit type.
One way that the latter is achieved is to look for marker/markers compounds that should not be present in a particular fruit.
One such type marker is sorbitol. This can prove very useful in some fruits that do not naturally contain this polyol above a certain level e.g. in raspberry and strawberry juices/purees for the presence of added apple, pear, plum; cherry or aronia for instance.
Another is tartaric acid. Here the addition of grape juice to other products, such as red/black juice & puree, can be detected
D-malic acid: Most fruits contain some malic acid, but the natural form in fruits is the L-compound. Now if the D-form is detected, which may be done using an enzymic procedure, this shows that D,L-malic acid has been added to the product and the material is adulterated.
In red/black juices the pattern of anthocyanins in a sample can be very useful at detecting the addition of another red/black fruits e.g. the addition of a black carrot extract to pomegranate juice for instance.
The addition of exogenous sugars to fruit juices and purees can be detected using a number of approaches.
A simple method that can be used is to measure the levels of the simple sugars (sucrose, glucose & fructose). However, due to the wide natural ranges that are seen for these sugars in fruit juices/purees the method is not very sensitive to detect juice adulteration
Isotopic methods (carbon-IRMS and deuterium-NMR) can be very useful here to detect the presence of exogenous sugars. The former approach is very good at detecting the addition of C4 derived sugars (cane/corn) to most juices (@ levels < ca 10%) except pineapple. The deuterium method can be used to detect the addition of C3 derived (beet/rice) derived sugars to most fruit juices (@ levels < ca 10%). Quantitative 13C-NMR can be used to detect the addition of C4 derived sugars to pineapple juice (@ levels < ca 15%).
A fingerprinting method based on Capillary Gas chromatography can be used to detect the presence of added sugar syrups (invert syrups, high fructose syrups from starch and high fructose syrups from inulin) to fruit juices.
The use of DNA based methods have also proved useful here. However, there are certain limitations here as DNA does not “like” being heated under acidic conditions, which is generally part of fruit juice processing. There are some DNA methods for the detection of mandarin juice in orange juice via a number of different procedures and the detection of mixtures of different types of mango varieties for instance.
The international fruit juice union (www.ifu-fruitjuice.com) have published a large number of methods specifically validated on fruit juices and purees that can assist in this area. However, this is only part of the issue as you need to be able to “interpret” the data that the method/s provide. Help can be found here in the published literature and/or at the European fruit juice association website (www.aijn.org). AIJN has prepared 25 reference guides that provide ranges for a number of important quality and authenticity parameters seen in the important fruit juices sold in the EU. These guidelines are used in the EU and other markets for the control of fruit juice quality and authenticity.
There is another screening method that is currently used in Europe to control the authenticity of fruit juices, which is based on proton nuclear magnetic resonance spectroscopy (1H-NMR). This approach is sold as a service by a number of companies in Europe.
Another aspect that has to be considered here is “what is the risk of adulteration for this product”. Some of the questions that you need to considered are:
Are there cheaper materials that can be added to the product to extend it? Almost certainly
Does this product have a history of adulteration? Almost certainly
Have you audited your supplier or has it been audited by a third party? (e.g. SGF IRMA (http://www.sgf.org/en/home/fks/halbwarenkontrolle/))
Are you buying from an unknown supplier through an agent of via worse via the internet!!
A number of companies can offer advice and analysis services in this area including the one I work for (www.eurofins.com). I have included a web reference to a talk I gave in Ireland in this area last year that I hope you find useful.
I hope you find this useful and if you need any further information please feel free to come back to me.
David
http://www.safefood.eu/SafeFood/media/SafeFoodLibrary/Documents/Professional/Events/David-Hammond_Eurofins-presentation.pdf