Today, most consumers are looking for authentic foods [5]. This growing demand is directly connected with market globalization, e-commerce, food chains, and national and international trade. In addition, due to strong economic motivations, more types of fraud are observed, including mislabeling and false declaration regarding origin (Figure 2). Food authentication according to the CEN Workshop Agreement 17,369:2019 is “a food product where there is a match between the actual food product characteristics and the corresponding food product claims; when the food product actually is that the claim says that is” [6]. Moreover, Codex Alimentarius described fraud as “any deliberate action of businesses or individuals to deceive others in regards to the integrity of food to gain undue advantage” [7]. The notion of honey authenticity has received great interest worldwide and increased focus in the last twenty years. However, prior to the commentary of the honey authenticity techniques one must distinguish the concept of “honey quality”, “honey standardization”, and “honey packaging” (Figure 3). Honey quality is a summary of characteristics that are considered important for determining the degree of acceptance by the consumer. Honey standardization is the process by which specifications are established of its production, the composition, and the properties. Finally, the packaging is their placement inside a packaging material to be protected from physical, chemical, and biological hazards and to be transported. According to the Scopus database, the most studied authenticity issue is the honey botanical origin differentiation. From reviewing, the most frequent analytical methods of honey botanical discrimination are classical and instrumental chemistry analyses. However, emphasis was given to specific botanical markers and/or in representative “fingerprint” spectra. Table 3 gives an overview of the most ordinary methods for honey authentication.

Analytical Technique	Abbreviation	Main Analytes and Parameters
Melissopalynological and Physicochemical techniques
Optical microscopy	OM	Pollen analysis
Scanning Electron Microscope	SEM
Hydroxymethylfurfural (HMF)
Phenolics
High-Performance Liquid Chromatography Refractive Index Detector
HPLC-RID
Sugars
High-Performance Liquid Chromatography Fluorescence Detector	HPLC-FS	Amino acids
		Phenolics
High-Performance Liquid Chromatography Pulsed Amperometric Detector	HPLC-PAD	Sugars
High-Performance Thin-Layer Chromatography	HPTLC	Phenolics
		Non-volatile components
		Sugars and/or fructose/glucose ratio
		Hydroxymethylfurfural (HMF)
Liquid Chromatography Mass Spectrometry	LC-MS	Hydroxymethylfurfural (HMF)
		Phenolics
Gas Chromatography Mass Spectrometry	GC-MS	Volatiles
		Semi-volatiles
Spectroscopic techniques
Ultraviolet–Visible Spectroscopy	UV–Vis	Spectrum of phenolics
Raman Spectroscopy	Raman	Sugars spectra and minor components
Fourier-Transform Mid-Infrared Spectroscopy	FT-MIR	Sugars spectra and minor components
Fourier-Transform Near-Infrared Spectroscopy	FT-NIR	Sugars spectra and minor components
Fluorescence Spectroscopy	FS	Spectra of amino acids, phenolics, Maillard reaction by-products
Nuclear Magnetic Resonance	NMR	Sugars, untargeted and targeted screening
Other techniques
Isotope-Ration Mass Spectrometry	IRMS	Isotope ration of H, C, N, S, and/or 13C ratios
Inductively Coupled Plasma Mass Spectrometry	ICP-MS	Chemical elements

2. Harvest, Honey Identity, and Authenticity Issues

2.1. Honey Harvesting

Honey harvesting is the most significant step before any further analysis. Honey is primarily a concentrated solution of sugars with other compounds such as organic acids, enzymes, vitamins, minerals, phenolics, and volatiles [8].

Honey composition is dependent on the plants that honeybees visit. Most beekeepers know the floral sources from which their honeybees collect nectar and pollen. This is because they consciously choose the flowering period and location of the hive. However, some beekeepers move the hives to more than one area in order to collect nectar sources from a wider area. In those cases, multifloral honey is produced. In addition, honey composition can be affected by beekeeper’s manipulations, postharvest processing [9], and storage conditions and length [10]. After harvesting, honey is subjected to various postharvest processing steps including extraction and sometimes dehumidification, liquefaction, heating, or pasteurization [11]. Finally, packaged honey must remain under cool and shady conditions before further use.

2.2. Classical Methods for Honey Authentication

Generally, melissopalynology is a microscopic analysis of honey and it is the basic method for determination of their botanical origin. Blossom honeys are considered mainly from one or more sources of pollen grains. According to legislation criteria, when the pollen content is over- or under-represented, honey can be characterized as unifloral or polyfloral. In addition, for honeydew honeys, the ratio of honeydew elements/pollen (HDE/P) is taken into account for botanical determination. Melissopalynological analysis constitutes a classic and widely used method for detecting botanical origin of Greek honey [12,13,14,15,16,17,18]. Tsigouri et al. [15] gave some palynological characteristics of 208 different monofloral honeys including fir, pine, chestnut, cotton, citrus, and thyme. Karabournioti et al. [13] carried out melissopalynological analysis in 135 thyme honeys and quantitated 65,000 pollen grains per 10 g of thyme honeys. More recently, Rodopoulou et al. [17] applied microscopic analysis to determine the botanical origin of thyme honeys, while they investigated the effects of over-presented pollen grains in blend honeys. However, they concluded that in some cases pollen analysis did not give trustworthy results and should be combined with other analyses. Recently, Tsiknakis et al. [18] applied machine learning to classify Cretan pollen grains with overall detection accuracy of 92%.

Pollen grains come mainly from the plants foraged by honeybees, while these pollens provide the botanical origin [19]. However, melissopalynological analysis requires specialized staff with experience in pollen grain recognition. Furthermore, this analysis always needs literature on beekeeping plants and optical or a scanning microscope for greater accuracy. Moreover, the possibility of human error is high with subjectivity in the entire process. Fraudulent counterfeiting actions, such as removing existing pollen and replacing it with another, could alter pollen content.

Reviewing the literature, many studies were based on physicochemical analyses to discriminate monofloral Greek honeys [12,16,17,20,21,22]. In most cases, physicochemical analyses showed a good success rate in classifying honey. Generally, honeydew honey is characterized by higher values of electric conductivity and acidity compared to blossom honey. On the other hand, blossom honey is richer in monosaccharides, and lighter colored. Further, physicochemical analyses as defined by Greek legislation provide information for quality (moisture must be lower than 20% 

w/w), freshness (diastase not lower than 8 Schade and HMF not higher than 40 mg/kg), stability, and shelf life of honey. Even so, sporadically, the dispersion of the above values, associated with the nature and heterogeneity of honey produces overlapping and reduces their usefulness. Physicochemical analyses overall are time-consuming and non-environmentally friendly techniques. In addition, they require large quantities of honey, a lot of chemical reagents, and trained labor. Even so, physiochemical analyses are a valuable reference and officially recognized methods and are widely used for the evaluation and characterization of blossom and honeydew honey, usually providing accurate and reliable results.