## 3 Results
### The Headspace Composition of Unifloral Bee Pollen
The principal compounds of _Q. pubescens_ bee pollen headspace were: acetic acid (21.69%), ethanol (9.44%), acetoin (7.07%), pentanal (11.85%), heptanal (5.37%), nonanal (15.57%) and (_E,E_)-octa-3,5-dien-2-one (5.08%). \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**No.** & **Compound** & & & & & & & & \\ \hline  & & RI & A & B & C & D & E & F \\ \cline{3-8}
1. & Acetic acid & \textless{}900 & - & - & - & 10.10 & 21.34 & 21.69 \\
2. & Ethanol & \textless{}900 & - & - & - & 6.93 & 7.17 & 9.44 \\
3. & Butanal & \textless{}900 & - & - & 4.66 & - & - & - \\
4. & 3-Methylbutanal & \textless{}900 & - & 3.73 & 4.57 & - & - & - \\
5. & 2-Methylbutanal & \textless{}900 & - & 3.71 & 5.42 & - & - & - \\
6. & 3-Hydroxybutan-2-one (acetoin) & \textless{}900 & - & 5.47 & 3.05 & - & 11.87 & 7.07 \\
7. & 3-Methylbutan-1-ol & \textless{}900 & - & 3.08 & 2.84 & 0.29 & - & - \\
8. & Pentanal & \textless{}900 & - & 4.14 & - & - & - & 11.85 \\
9. & Butane-1,3-diol & \textless{}900 & - & - & - & - & 1.52 & - \\
10. & Butane-2,3-diol & \textless{}900 & - & - & - & - & 1.80 & - \\
11. & (_E_)-Hex-2-enal & \textless{}900 & - & - & - & 0.12 & - & 0.94 \\
12. & 3-Methylpentanal ** & \textless{}900 & - & - & 10.37 & - & - & - \\
13. & Hexanal & \textless{}900 & 0.40 & 7.02 & 1.62 & 1.22 & 2.89 & - \\
14. & Hexan-1-ol & \textless{}900 & - & - & - & 1.46 & 1.62 & 2.63 \\
15. & Heptanal & 904 & - & 5.17 & - & 0.49 & - & 5.37 \\
16. & \textgreater{}-Butylrolactone & 922 & 0.09 & - & - & 0.43 & 0.66 & - \\
17. & Methyl hexanoate & 928 & - & - & 0.53 & - & 0.48 & 0.60 \\
18. & \textasci{}a-Pinene & 942 & - & - & - & 0.45 & - & - \\
19. & 3-Methylpentanoic acid & 954 & - & - & 3.12 & - & - & - \\
20. & \textasci{}-Valerolactone & 960 & - & - & - & 0.37 & - & - \\
21. & Benzaldehyde & 969 & 0.65 & 11.93 & 28.98 & 0.63 & 2.73 & 1.39 \\
22. & \textasci{}\beta\)-Pinene & 985 & - & - & - & 0.94 & 0.89 & - \\
23. & 6-Methylhept-5 en-2-one & 989 & 0.25 & 2.68 & 2.20 & 0.80 & 2.05 & 2.96 \\
24. & \textasci{}\beta\)-Mycrene & 993 & - & - & - & 1.46 & - & - \\
25. & Octanal & 1005 & 0.14 & 1.90 & 0.48 & 0.55 & 0.91 & 1.35 \\
26. & (_E,E_)-Hepta-2,4-dienal & 1015 & - & - & - & 0.34 & 0.39 & 2.09 \\
27. & 6-Phellandrene & 1034 & - & - & - & 5.69 & - & - \\
28. & 2-Ethylhexan-1-ol & 1035 & - & - & - & 0.11 & - & - \\
29. & 1,8-Cineole & 1039 & - & - & - & - & 0.77 & - \\
30. & Benzyl alcohol & 1046 & - & - & 1.17 & - & - & - \\
31. & Phenylacetaldehyde & 1050 & 1.04 & 0.38 & 3.95 & 0.25 & 2.28 & 1.35 \\
32. & (_E_)-\(\beta\)-Coymene & 1053 & - & 0.92 & - & - & - & - \\
33. & (_E,E_)-Octa-3,5-diene-2-one & 1075 & - & - & 0.54 & 2.46 & 3.52 & 5.08 \\
34. & (_E,Z_)-Octa-3,5-diene-2-one & 1096 & - & - & - & 0.45 & 0.44 & 1.85 \\
35. & Linanol & 1103 & - & - & - & - & 0.91 & - \\
36. & Nonanal & 1105 & 1.53 & 9.28 & 1.24 & 8.09 & 3.81 & 15.57 \\
37. & Methyl octanoate & 1128 & - & - & 0.89 & - & 1.87 & 0.38 \\
38. & Lilac aldehyde A & 1147 & 14.84 & 6.06 & 3.85 & - & - & - \\
39. & Lilac aldehyde B & 1155 & 29.30 & 10.43 & 6.42 & - & - & - \\
40. & Lilac aldehyde D & 1169 & 13.37 & 3.94 & 2.48 & - & - & - \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Volatile headspace compounds (%) from the bee pollen samples collected from mountain region. The bee pollen collected from AR was composed of the bee pollen from _Q. puhescens_, _Malus_ spp., _S. vulgaris_, _R. lutea_, _C. biennis_, and _P. mahaleb_ (Table 5). The bee pollen HS of _Q. puhescens_ contained, as the major compounds, acetic acid (6.93%), hexanal (4.88%), heptanal (4.46%), benzaldehyde (4.88%), 6-methylhept-5-en-2-one (5.81%), phenylacetaldehyde (5.46%) and nonanal (28.67%). _Malus_ spp. bee pollen HS contained, as dominant compounds, pentanal (1.46%), hexanal (3.56%), heptanal (2.19%) and nonanal (15.53%) followed by 6-methylhept-5-en-2-one (8.33%). Other abundant compounds were benzene derivatives benzaldehyde (6.36%), phenylacetaldehyde (5.69%) and 2-phenylethanol (2.60%). Acetic acid (9.30%) and acetoin (3.99%) were also detected. HS VOCs of _S.