# Volatilome and Bioaccessible Phenolics Profiles in Lab-Scale Fermented Bee Pollen
## 3 Results and Discussion
### Volatilome Analysis
kunkeei_ selected strains in Started-BCP, which drove the BCP fermentation processes [13]. The high level of acetic acid detected into Unstarted-BCP was likely due to the variety of bacteria naturally associated to the BCP (e.g., Alpha 2.2 bacteria, _A. kunkeei_, Actinobacteria) that may have had a role during spontaneous fermentation of Unstarted-BCP [14; 39]. Furthermore. VFFA, like hexanoic acid, 2-methyl-decanoic acid, and 3-methyl-butanoic acid, significantly increased (_p_ < 0.05) in both Unstarted- and Started-BCP (Figure 2). This is consistent with the decrease of aldehydes, like hexanal andnonanal, which were likely oxidized to the corresponding acids. We may not exclude a role of the \(H\). _uwarum_ AN8Y27B or of the authochthonous yeasts in the VFFA increase. Short and medium fatty acids are produced by yeasts as intermediates in the biosynthesis of long-chain fatty acids for their cellular membrane [40]. The release of VFFA by yeasts is strongly species- and strain-dependent. VFFA may significantly contribute to the BCP flavour, and are usually associated with sweaty, grass, cheesy, fatty, acid, or rancid notes [41]. The increase of VFFA during BCP fermentation was in agreement with the higher (\(p<0.05\)) TTA values observed in Started- (135 \(\pm\) 3 mL NaOH 0.1 M per 10 g of BCP) and Unstarted-BCP (130 \(\pm\) 4 mL NaOH 0.1 M per 10 g of BCP) compared to Raw-BCP (52 \(\pm\) 4 mL NaOH 0.1 M per 10 g of BCP). Figure 1: Concentration (ppb) of volatile free fatty acids (VFFA), alkanes, alkenes, alcohols, aldehydes, ketones, esters, furans, lacton (2(3H)-furanone, dihydro-5-methyl-), terpenes, sulphur compound (dimethyl sulfide), and total volatile compounds (total VOC identified in Raw- (black bars), Unstarted- (blue bars), and Started-bee-collected pollen (BCP) (red bars). Data are the means (\(\pm\) SD) of three independent experiments analyzed in triplicate. Data were subjected to one-way analysis of variance (ANOVA); pair-comparison of treatment means was achieved by [PERSON]’s procedure at \(p<0.05\). For each chemical group, bars with different superscript letters differ significantly (\(p<0.05\)). Ketones may give a noticeable contribution to aroma in food. Six-methyl-5-Hepten-2-one (1244 \(\pm\) 121 ppb), 3,5-Octadien-2-one (719 \(\pm\) 25 ppb), and 2 methyl-cyclopentanone (397 \(\pm\) 10 ppb) were the most abundant in Raw-BCP (Figure 3). The formation of ketones was likely due to the yeasts, especially methyl ketones which arise from incomplete \(\beta\)-oxidation of fatty acids [42; 43]. Ketones may either be oxygenated to esters or be reduced to the corresponding alcohols [44; 45; 46]. Overall, the level of ketones increased in both fermented samples (Figure 3). The highest increase was detected for the 6-methyl-5-hepten-2-one (2158 \(\pm\) 92 and 1735 \(\pm\) 57 ppb in Unstarted- and Started-BCP, respectively) (Figure 3). On the other hand, a noticeable decrease of 3,5-Octadien-2-one was also found in fermented BCP samples, with final concentrations of 99 \(\pm\) 2 and 83 \(\pm\) 6 ppb in Unstarted- and Started-BCP, respectively. 1-Penten-3-ol (1101 \(\pm\) 74 ppb), 1-hexanol (813 \(\pm\) 42 ppb), and ethanol (576 \(\pm\) 53 ppb) were the main alcohols detected in Raw-BCP (Figure 4). During fermentation ethanol increased (_p_ < 0.05) more than five and seven folds in Unstarted- and Started-BCP, respectively (Figure 4). _A. kunkexi_ strains are unable to synthetize ethanol through the 6-phosphogluconate/ phosphoketolase pathway, due to the lack of alcohol dehydrogenase activity [20]. Thus, the noticeable production of ethanol may be traced back to the metabolism of _H. uvarum_ AN8Y27B or by autochthonous yeasts. 1-Nonanol and 1-hexanol also sharply increased, especially in Started-BCP, and overall, an increasing trend was found during fermentation for most of the detected alcohols (Figure 4). As reported above, alcohols may originate from the reduction of aldehyde.