Original papers Honey authentication based on physicochemical parameters and phenolic compounds Mircea Oroian ⇑ , Ropciuc Sorina Faculty of Food Engineering, Stefan cel Mare University of Suceava, Romania article info Article history: Received 5 October 2016 Received in revised form 24 April 2017 Accepted 25 April 2017 Keywords: Honey Authentication Phenolics Physicochemical properties Chemometrics abstract The aim of this study is to assess the usefulness of physicochemical parameters (pH, water activity, free acidity, refraction index, Brix, moisture content and ash content), color parameters (L/,a/,b/, chroma, hue angle and yellow index) and phenolics (quercetin, apigenin, myricetin, isorhamnetin, kaempherol, caffeic acid, chrysin, galangin, luteolin, p-coumaric acid, gallic acid and pinocembrin) in view of classify- ing honeys according to their botanical origin (acacia, tilia, sunflower, honeydew and polyfloral). Thus, the classification of honeys has been made using the principal component analysis (PCA), linear discrim- inant analysis (LDA) and artificial neural networks (ANN). The multilayer perceptron network with 2 hid- den layers classified correctly 94.8% of the cross validated samples. Ó 2017 Elsevier B.V. All rights reserved. 1. Introduction Honey is an ancient food, which is largely consumed due to its nutritional, medicinal and cosmetic properties. The high value of honey is given by its nutritional value, macro and microelements and many other compounds it contains (Jasicka-Misiak et al., 2012). The honey composition (sugars, organic acids, enzymes, vitamins, proteins and phytochemicals) is influenced by the botan- ical and geographical origin and environmental climatic conditions (Baroni et al., 2015; Solayman et al., 2016). Glucose and fructose are the major sugars present in honey, but there have been reported smaller quantities of twenty-two other compounds (e.g. maltose, sucrose, maltulose, turanose, isomaltose, etc.) (Siddiqui et al., 2017). Honey contains different types of enzymes such as: oxidase, catalyse, acid phospatase, invertase and diastase, which make it unique in the sweeteners domain. Moisture content, reducing sugars, free acids, electrical conductivity, sucrose content and 5-HMF influence nutritional quality, granulation, flavor and texture parameters. In addition to the previously mentioned compounds, phyto-chemical compounds present in honey play a major role in determining the antioxidant activity, which can be correlated with the anti-inflammatory, anti-carcinogenic, anti- thrombotic, anti-atherogenic activity of honey (Piljac-Z ˇ egarac et al., 2009). Among the phyto-chemical compounds present in honey, the phenolic compounds play a major role in the antioxi- dant activity. The phenolic compounds found in honey are free phenols, phenolic acids, polyphenols (usually in the form of flavo- noids), anthocyanins, procyanidins and pigments. Their total con- tent depends on the species of plant from which bees collected the nectar and their amount varies from 5 to 1300 mg/kg (Mattonai et al., 2016; Mellen et al., 2015). The necessity for determining some parameters in terms of the botanical or geographical authentication of honeys derives from the increasing demand for mono-floral honeys on markets. Mono-floral honeys are more expensive than multi-floral ones. A honey can be mono-floral or polyfloral in origin depending on whether it is derived from one or several plant species. According to the international food standards, for a honey to be labelled with floral origin, it must originate wholly or predominantly from a par- ticular floral source and display the corresponding organoleptic, physicochemical and microscopic properties (Codex Alimentarius, 2001). Adulteration of honey can be determined using the quality parameters, and these parameters can confirm the hygiene condi- tions for the manipulation and storage of honey (da Silva et al., 2016). The authentication of honey has started with the melissopaly- nological method, which can be used for botanical authentication (Karabagias et al., 2014). An alternative for honey authentication is the combination of melissopalynological method with physico- chemical parameters (Oroian et al., 2015a; Karabagias et al., 2014; Escriche et al., 2014; Juan-Borrás et al., 2014). Over the last decades there have been implemented different methods for the authentication of honey such as: e-tongue and optical http://dx.doi.org/10.1016/j.compag.2017.04.020 0168-1699/Ó 2017 Elsevier B.V. All rights reserved. ⇑ Corresponding author. E-mail address: m.oroian@fia.usv.ro (M. Oroian). Computers and Electronics in Agriculture 138 (2017) 148–156 Contents lists available at ScienceDirect Computers and Electronics in Agriculture journal homepage: www.elsevier.com/locate/compag