## Results and Discussion
### Physicochemical Parameter Values of Portuguese Honey Samples
In addition, significant differences (\(p<0.05\)) were observed among honey types of different botanical and geographical origin in the moisture content. Moisture content of Portuguese honeys ranged between 15.23 \(\pm\) 0.15 to 17.93 \(\pm\) 0.06. The lowest value was recorded for chestnut honey from Braganca region and the highest value was recorded for eucalyptus honey from Esposende region. In total, moisture content values are in accordance with the EU council directive relating to honey [1], in which the value of 20% (g/100 g) has been defined as the upper moisture limit for marketed honeys. Of course some exceptions may occur in honey types such as _Erica_ spp. (_Calluna_) in which the moisture upper limit may be 23%. From a scientific point of view, the determination of moisture is related to honey preservation and storage, as high water content can lead to the growth of moulds, that may alter a product's flavour and shelf-life [16]. However, the differences observed between honey samples may be due to environmental conditions, harvesting year and the degree of honey maturity reached in the beehive [31]. These moisture content values agree with previous studies on Portuguese honeys [15; 17; 18; 19; 29]. The pH values ranged from 3.62 \(\pm\) 0.01 to 4.42 \(\pm\) 0.01, with significant differences (\(p<0.05\)) between samples (Table 2). Briefly, the lower pH value (effective acidity) was recorded for eucalyptus honey from Esposende region, whereas the higher pH value was recorded for chestnut honey from Braganca region. Even though there is not a specified pH value for honey the determination of this parameter is of significant importance as it may influence honey texture, stability and shelf life [32]. Low pH values inhibit the presence and growth of microorganisms. Such pH values are consistent with some studies on Portuguese honeys [16; 17; 18; 19; 29]. Electrical conductivity of honey is owed to minerals and trace elements, small amounts of proteins or any other charged molecule released in the aqueous form of a honey solution. It is a conventional physicochemical parameter that it has been correlated with the botanical origin of honey and it is used for honey botanical origin identification in combination with melissopalynological analysis data. The eucalyptus honeys showed the lower electrical conductivity values, whereas chestnut honeys the highest (Table 2). The electrical conductivity values of eucalyptus honey samples analysed in the present study are in conformity with previous studies in the literature involving eucalyptus honeys [17]. The electrical conductivity value of heather honey is in excellent agreement with those of a previous study on Portuguese heather honeys [29]. According to the EU Council directive [1] the maximum limit value of electrical conductivity for blossom honey is 0.80 mS/cm, while honeyhew honeys have electrical conductivity values \(\geq\)0.80 mS/cm. Total dissolved solids reflect all inorganic and organic molecules that are present in honey in molecular, ionized or micro-granular (colloidal solution) suspended forms [33]. TDS recorded higher values (mg/L) in chestnut honeys followed by those of heather and eucalyptus honeys (Table 2). What is remarkable is that the observed differences were significant (\(p<0.05\)) according to Portuguese honey botanical and geographical origin. On the other hand, salinity is a measure of the saltness or dissolved salt content in an aqueous medium. For instance, chestnut honeys recorded the highest salinity values (g/L) followed by heather and eucalyptus honeys. To the best of our knowledge, data on TDS and salinity contents have never been reported before for Portuguese honeys. Available data in the literature originate from Algerian, Greek, Cypriot and Egyptian floral honeys [33; 34], in which TDS and salinity contents values recorded fluctuations according to honey botanical and geographical origin, in agreement with the results of the present study.