## 1 Introduction  
The most common and economically important varieties of Satsuma mandarin (_Citrus unshiu_ Marc.) in Croatia (Neretva valley, Opuzen area) are _Wakiyama_, _Chahara_, _Okitsu_, _Kauano Wase_, _Ouari_, _Saign_, _Kuno_, _Zorica_, _Ichumare_, and _Seto_[1]. Around 2.5 million mandarin trees have been planted [1] in the Opuzen area (ca. 2500 ha) providing a good nectar source for unifloral honey production and potential for independent commercialization (not just as _Citrus_ honey without distinction of the species). _C. unshiu_ honey has not yet been characterized in detail. Melissopalynological analysis, based on the identification and quantification of the pollen percentage by microscopic examination, has been accepted as the reference method to authenticate honey botanical origin [2]. However, pollen analysis is considered of little value for the _Citrus_ genus as it is one of several honey types with underrepresented pollen [34]. Accordingly, _C. unshiu_ honey characterisation is difficult with underrepresented pollen due to the specific plant physiology of particular mandarin cultivars (aborted anthers, sterile pollen grains, or partenocarpy). Therefore, there is a need for detailed chemical characterisation of _C. unshiu_ honey and present research is focused on its volatile organic compounds (VOCs). The usefulness of VOC analysis in the determination of the honey botanical origin has been reported previously [5; 6; 7]. The aroma profile can be considered to be a \"fingerprint\" of unifloral honey directly related to the plant nectar [8]. _Citrus_ honey has been often analysed without distinction between different species (_C. sinensis_ L., _C. deliciosa_ Ten., _C. limon_ L., etc.) or, at best, as orange/lemon blossom honey. The extracts from _Citrus_ honey contain linaloal derivatives, such as (_E_)-2,6-dimethylocta-2,7-diene-1,6-diol, 2,6-dimethylocta-3,7-diene-2,6-diol or (_Z_)-2,6-dimethylocta-2,7-diene-1,6-diol [9]. Higher concentrations of linaloal oxides and linac aldehydes/alcohols were also found in the honey headspace [10; 11; 12; 13]. \(\alpha\)-4-Dimethylcyclohex-3-ene-1-acetaldehyde was present in Greek _Citrus_ honey [10]. Methyl anthranilate has been suggested as a _Citrus_ honey floral marker [14]. Two isomers of sinensal, the volatile component of orange essential oil, were identified in Spanish _Citrus_ honey [12]. The enantiomeric ratio between (_3S_)-linalool and (_3R_)-linalool in orange honey was about 13:87 similar as in orange flowers, and _trans_-(2\(R\),5R_)-linalool oxide with _cis_-(2\(S\),5R_)-linalool oxide prevailed [15]. The volatiles composition, physicochemical parameters, flavonoids and phenolic compounds were used as tools in the statistical analysis for the differentiation of lemon and orange honey [16; 17]. A stepwise discriminant analysis using 37 volatiles and different parameters (diastase, conductivity, Pfund colour, and CIE L*a*b*) provided the model for classification of the samples. A multivariate PLS2 analysis showed that linac aldehydes and phenylacetaldehyde (all abundant in orange honey) were negatively correlated with four flavonoids (pinochemyrin, chrysin, naringenin, and quercetin) and caffeic acid, all abundant in lemon honey. Moreover, the last five compounds were positively correlated with six alcohols, two ketones, acetaldehyde, and furanmethanol. In addition, caffeine is present in _Citrus_ honey at about 1-10 mg/kg [18]. Basic physicochemical parameters of _C. unshiu_ honey were determined in our previous research [19] with the following average values: water content 16.00%, electrical conductivity 0.23 mS-cm\({}^{-1}\), fructose and glucose 77.33%, saccharose 1.5%, free acidity 15.10 mEq\(\cdot\)kg\({}^{-1}\) and diastase activity 10.60 (DN). The present research emphases: (a) the headspace, volatile and semi-volatile nectar compounds from the varieties _Zorica_, _Chahara_, _Kavano Wase_, and _Okitsu_, from the honey-sac of the bees returning from _C.