*3.10. Principal Component Analysis*

The PCA was conducted based on the analysis discussed in order to discriminate the bee pollen samples based on their botanical origin. The first two principal components (PC1 and PC2) explained 77% of the data variance (PC1 explained 50% of the data variance, while PC2 explained 27% of the data variance). The PC1 is influenced strongly by lipids and negatively by raffinose and C18:2, the PC2 is influenced positively by quercetin while myricetin influences it negatively. Propionic acid, C17:1, TFC and asparagine do not influence the projection of the scores due to their closeness to the origins of the two PC. As can be seen in Figure 2A, the samples with high percentage of *Helianthus annus*, *Robinia pseudoacacia*, *Pinaceae* spp., *Quercus* spp. and *Prunus* spp. formed clusters which confirms that the analysis carried out is useful for their discrimination. Regarding the polyfloral bee pollen it can be observed that the samples are near on the other one but they include in their region the bee pollen from *Crataegus monogyna*, *Tilia* spp. and *Taraxacum*. The *Quercus* spp. and *Crataegus monogyna* exhibited a high myricetin content, while *Prunus* spp. exhibited a high quercetin content. The *Helianthus annus* samples exhibited a high free acidity, C18:0, F/G, lactic acid, lipids and C20:1. The polyfloral samples exhibited a high by raffinose and C18:2, myricetin and raffinose (Figure 2B). The *Robinia pseudoacacia* pollen samples were associated with C15:0, chlorogenic acid, turanose, maltose, C17:0, and *p*-hydroxibenzoic acid. A high positive correlation between moisture content and water activity (r = 0.898), moisture content and F/G (r = 0.818) was observed. The lipids content was positively correlated with C18:1 [trans-9]) + (C18:1 [cis-9] (r = 0.812), C18:2 [cis-9,12] (r = 0.898), C18:3 [cis-6,9,12] (r = 0.852), C22:2 [cis-13,16] (r = 0.772), MUFA (r = 0.796), PUFA (r = 0.870), UFA (r = 0.869) and SFA (r = 0.825). The TPC and TFC were correlated positively with quercetin (r = 0.579, r = 0.705) and kaempferol (r = 0.705, r = 0.679). The protein content was correlated with proline (r = 0.309) and asparagine (r = 0.302). The energetic value was correlated negatively with moisture content (r = −0.527), and positively with lipids (r = 0.587), sucrose (r = 0.328), MUFA (r = 0.620) and PUFA (r = 0.591).

**Figure 2.** *Cont*.

(**B**)

**Figure 2.** Principal component analysis scores (**A**) and loadings (**B**) of the bee pollen based on their physicochemical, organic acids, sugars, TPC, TFC, phenolics compounds, amino acids, fatty acids: a—scores, b—loadings, Fa-free acidity, Mo—moisture content, Fa-lipids, p-protein content, Fru-fructose, Glu-glucose, Suc-sucrose, Tur-turanose, Mal-maltose, Tre-trehalose, Mel-melesitose, Raf-raffinose, GluA-gluconic acid, LacA-lactic acid, AceA-acetic acid, ProA- propionic acid, TPC-total phenolic content, TFC-total flavone content, p-a—protocatecuic acid, 4-h-a—p-hydroxibenzoic acid, C-a—chlorogenic acid, p-c-A—p-coumaric acid, R-a—rosmarinic acid, V-A vanillic acid, Ala-alanine, Sar-Sarcosine, Gly-glicine, Val-valine, Leu-leucine, Iso—isoleucine, Thr-threonine, Ser-Serine, Pro-Proline, Asp-asparagine, AspA-aspartic acid, Phe-phenylalanine, GluA-glumatic acid, His-histidine, Lys-lysine, Tyr-tyrosine, Tryp-tryptophan.
