*3.7. Total Free Amino Acid Composition*

As the data presented in Table 4 states, 16 amino acids (eight essential amino acids and eight non-essential amino acids) were quantified in the bee pollen samples analyzed, and there was observed a significant difference in terms of amino acids concentration between the samples (*p* < 0.05). The total content of the amino acids determined for the bee pollen samples varied between 11.31 μg/mg (sample 21) and 45.99 μg/mg (sample 4). These values were comparable to those reported for the total free amino acid content of commercial bee pollen from Colombia (25.3 ± 1.0 mg/g), Italy (29.4 ± 0.7 mg/g) and Spain (30.8 ± 0.2 mg/g) [22], and higher than the total amino acids content of bee pollen from floral sources such as sunflower (12.20 g/100 g) and rape (12.25 g/100 g) [49]. From the data presented, in the samples analyzed in our study, the most abundant essential amino acids were histidine (values of 0.29–2.30 μg/mg), lysine (0.14–0.74 μg/mg) and phenylalanine (0.12–0.43 μg/mg). Histidine was found to predominate in the bee pollen collected during autumn, while high levels of lysine and phenylalanine were determined in bee pollen collected during winter [50]. The distribution of these essential amino acids in the analyzed bee pollen was therefore in accordance with the period when the samples were collected. Leucine, isoleucine and tryptophan were detected in low amounts, and similar findings were reported for monofloral bee pollen of *Geranium* botanical origin [15]. Glutamic acid was the main amino acid in all bee pollen samples, with values that varied between 0.34 and 18.77 μg/mg, followed by aspartic acid (0.01–14.08 μg/mg) and proline (2.79–7.19 μg/mg). Glutamic acid, aspartic acid and proline were also reported as the major amino acids in different bee pollen varieties (coconut, coriander, rapeseed and multifloral) from India [27]. The variation of the amino acid content was found to be influenced by both botanical origin and processing and storage conditions. In regard to the processing

and storage conditions, previous studies reported that glutamic acid is the most abundant amino acid in bee pollen that is freshly collected, while proline is the free amino acid that is found in high amounts in well dried and stored bee pollen [22]. In the case of our study, the high content of glutamic acid was well correlated to the fact that the bee pollen samples analyzed in this study were freshly collected.
