The new tendency to detect adulterated honey is the development of affordable analytical equipment that is in-line and manageable, enabling rapid on site screening. Therefore, the aim of this work was to apply an electronic tongue based on potential multistep pulse voltammetry, in combination with multivariate statistical techniques to detect and quantify syrup in honey. Pure monofloral honey (heather, orange blossom and sunflower), syrup (rice, barley and corn), and samples simulating adulterated honey with different percentages of syrup (2.5, 5, 10, 20 and 40) were evaluated. An automatic, electrochemical system for cleaning and polishing the electronic tongue sensors (Ir, Rh, Pt, Au) significantly improved the repeatability and accuracy of the measurements. PCA analysis showed that the proposed methodology is able to distinguish between types of pure honey and syrup, and their different levels of adulterants. A subsequent PLS analysis successfully predicted the level of the 2 adulterants in each honey, achieving good correlations considering the adjusting parameters. The best results being for sunflower honey adulterated with corn syrup and heather honey with barley syrup (r 2 =0.997), and heather with corn (r 2 =0.994) whereas the weakest was found for heather honey adulterated with brown rice syrup (r 2 =0.763) and orange blossom honey with corn syrup (r 2 =0.879). The measurement system here proposed could be a very quick and effective option for the honey packaging sector with the finality of providing information about a characteristic as important as the adulteration of honey.

The proliferation of hybrid plant varieties without pollen, such as lavender, has complicated the classification of specific types of honey. This study evaluated the correlation between the proclaimed type of monofloral honey (lavender or thyme) as appears on the label with the actual percentage of pollen. In addition, physicochemical parameters, colour, olfacto-gustatory profile, and volatile compounds were tested. All of the samples labelled as lavender were wrongly classified according to the usual commercial criteria (minimum 10% of pollen Lavandula spp.). In the case of lavender honey, there was significant agreement between commercial labelling and classification through organoleptic perception (81.8%), and above all between the commercial labelling and the volatile compounds (90.9%). For thyme honey, agreement for both parameters was 90.0%. These results offer compelling evidence that the volatile compounds are useful for the classification of lavender honey with low levels of pollen since this technique agrees well with the organoleptic analysis.

6Ensuring the authenticity of honey is a priority for producers and regulatory authorities. 7The aim of this work was to evaluate the thermal properties (using a Differential Scanning 8 Calorimeter "DSC") of ten types of sugar syrup, six types of honey and the mixtures of 9 sunflower honey with all these syrups at different proportions simulating the adulteration 10 of honey (ratio honey/syrup: 80/20; 90/10; 95/05). The glass transition temperature (Tg 11 midpoint) ranged from 60.2 ºC to 67.3 ºC in honey samples and from 32.8 ºC to 95.8 ºC 12 in syrup samples. The differences in sugar composition of the syrups mainly affect their 13 thermal properties. In the adulterated samples, the glass transition temperature was 14 affected by the type of syrup, proportionally to the adulteration level. These results offer 15 compelling evidence that the DSC can be used for the identification of addition of syrup 16to honey, although to be conclusive a greater number of honey types must be considered.

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BACKGROUND: The growing need to classify the origin of honey in a simple way is leading to the development of affordable analytical equipment that is in-line and manageable, enabling rapid on-site screening. The aim of this work was therefore to evaluate whether an electronic tongue (made of four metallic electrodes: Ir, Rh, Pt, Au), based on potential multistep pulse voltammetry with electrochemical polishing, is able to differentiate between honey samples from Spain, Honduras, and Mozambique.RESULTS: It was demonstrated, for the first time, that automatic pulse voltammetry, in combination with principal component analysis (PCA) statistical analysis, was able to differentiate honey samples from these three countries. A partial least squares (PLS) analysis predicted the level of certain physicochemical parameters, the best results being for conductivity and moisture with correlation coefficients of 0.948 and 0.879, whereas the weakest correlation was for the sugars. CONCLUSION:The tool proposed in this study could be applied to identify the country origin of the three types of multifloral honey considered here. It also offers promising perspectives for expanding knowledge of the provenance of honey. All of this could be achieved when a comprehensive database with the information generated by this electronic tongue has been created.