Introduction to the 6th OLEUM newsletter

OLEUM: update on new methods and materials for addressing the quality and authenticity of olive oil

By Tullia Gallina Toschi and Paul Brereton

 

The world of olive oil (OO) faces daily problems related to its quality and authenticity. OO and, in particular, extra virgin olive oil (EVOO), are top quality products in terms of nutritional and, in the case of the latter, sensory attributes. EVOO has a higher market value, (15 to 100%) than the lowest commodity category of virgin olive oil (VOO). This value is mainly due to sensory attributes since “EXTRA” effectively means the absence of any sensory defect. Indeed, representing the site of the added value, this “EXTRA” quality in where the interest of fraudsters is located. This is confirmed by the fact that the largest number of non-conformities recorded in Europe concern sensory quality. What to do, then? OLEUM‘s aim is to develop and validate methods that can assist and support the sensory assessment, i.e. the Panel Test, and thereby protect the consumer from false claims on the label of the bottle.
 

Given that the greatest disagreements in sensory classifications are found at the so-called “borderlines” of EVOO quality, it is very useful to have instrumental methods to identify and quantify key volatile compounds that contribute to the sensory analysis. One of the methods proposed for validation is the SPME-GC / MS or SPME-GC / FID (Method 4A) procedure. This targeted (it measures specific “target” compounds) method is proposed to be used as a possible complementary test in case of disagreement between panels (Fig. 1). Eventually could be also be used to “anticipate” the results of the panel test as a quality assurance measure.  Before it can be suitable for use it is necessary to verify the method performance parameters of the procedure, including the reproducibility of the quantification of specific volatile compounds. This will allow the compilation of reliable limits and ranges for the different grades of VOO that could be presented to the International Olive Council (IOC) for adoption.
 

Additionally, OLEUM also proposes to carry out one of the first studies aimed at developing method performance characteristics for a non-targeted method (where the focus is on obtaining and comparing the profile of volatile compounds)  (Method 4B). Many instrument companies have been proposing, over the last few years, to authenticate food products using rapid non-targeted methods (NTMs), but their implementation has been hampered by the lack of a formal validation process. Oleum is contributing to this new area by producing reference materials and carrying out interlaboratory comparison studies on NTMs.  In this way, we will be able to compare the performance of both targeted and non-targeted methods for assessing volatiles thereby taking NTMs one step closer to implementation.
 

Finally, three other methods are being validated within the OLEUM; one (Method 1) that measures “polyphenols” in accordance with the health claim (Reg. EU 432/2012) and a second (Method 2) that measures free and esterified sterols thus providing additional information useful for authenticity and detection of the addition of other vegetable oils. Another method undergoing validation is the revision of the official method for the determination of fatty acid ethyl esters (FAEEs), using an improved faster process by Solid Phase Extraction (SPE), rather than the current traditional column procedure (Method 3).
 

The last challenge is to have internationally recognized, validated and reproducible reference materials, in particular sensory ones. OLEUM is undertaking a validation exercise evaluating the intensity and usefulness of two reference materials: one a material for the recognition of winey-vinegary defect, and one for the rancid (Method 4C).
 

 

 

Fig. 1 Possible use of a targeted instrumental approach as a confirmation/disconfirmation tool of the sensory assessment (Panel Test).