## 3 Results and Discussion
### VOCs Profile of Honey
Acetic acid (Ac1), which is present in all five honeys, was found at significant levels in indigo and astragalus honey (16.93% and 5.63% of the total acid area, respectively) (Table 3). This compound, which gives spicy flavors and aromas, has previously been reported as one of the major volatile components of astragalus honey, and in several other kinds of honey, such as buckwheat, chestnut, acacia, pine, eucalyptus, lime tree, fir tree, lavender, honeydew, orange, rape, hhododend, thyme, rosmear, and sunflower [92]. Formic acid (Ac2), present at significant levels in indigo and astragalus honeys, is antibacterial. In contrast, butanoic acid (Ac3) can inhibit colon cancer and inflammation-mediated ulcerative colitis [95]. Finally, benzoic acid (Ac9) has shown antifungal activity, inhibiting the growth of moulds, yeasts, and some bacteria [95]. Aldehyde compounds represented 31.42% and 27.49% of the total peak area in astragalus and alfalfa honeys, respectively. In the volatile profile of sainfoin and indigo honeys, the percentage of aldehydes varies from 11.22% to 17.18%, respectively, while these compounds are present in very low amounts in caroh honey (0.62%) (Table 3). Among aldehydes, the main constituent for astragalus (15.38% of the total aldehyde area) and indigo (7.01%) samples is Ald12, 5-hydroxymethyl-2-furfural (5 HMF), a heterocyclic organic compound that occurs naturally in sugar-containing fresh foods, including milk and honey. The main constituents of alfalfa honey were two aldehydes considered ubiquitous in many other kinds of honey, Ald6 (benzaldehyde) and Ald5 (2-furfural), each representing about 8% of all aldehyde's peak areas (Table 3). Ald12, produced during food pasteurization and cooking due to dehydration of certain sugars, is also formed during extended food storage under acidic conditions that favour its generation [96]. Therefore, the high percentage of Ald12 in astragalus and indigo honey can be correlated to the significant presence of acids that can catalyze fructose and glucose to form 5-HMF in honey. Alcohols represented 20.59 and 13.26% of the total peak area in alfalfa and indigo honey, respectively. In the volatile profile of astragalus and sainfoin honeys, the percentage of alcohols was around 6%, while for caroh honey, it was very low (0.92%). Significant levels of phenyl ethyl alcohol (A12), existent in all kinds of honey, were found in indigo and sainfoin samples (6.17% and 4.59% of the total alcohol peak area, respectively) (Table 3). With a floral odor, this aromatic compound has previously been reported as contributing to the aroma of a wide variety of European honeys [97]. In the volatile profile of indigo honey, 2-furan methanol (A8) was also present (about 5% of the total alcohol peak area), which is a furan-derived compound considered, like Ald5, to be a potential indicator of honey spoilage due to poor storage conditions or thermal processes [95]. For alfalfa samples, among the alcohols, the principal constituent (4.48% of the total alcohol peak area) is A11 (benzyl alcohol), a benzene derivative reported--as well as Ald6 (benzaldehyde) and phenyl ethyl alcohol (A12)--in many honeys with different floral origins [98]. Honey volatile compounds, such as 2-furfural (Ald5), benzaldehyde (Ald6), benzene acetaldehyde (Ald8), 2-furan methanol (A8), or phenyl ethyl alcohol (A12), have shown antimicrobial activity [92; 95]. Ester compounds, utterly absent in alfalfa and indigo honey, are predominant in sainfoin honey from the point of view of number (8), even if they represent only 2% of the total peak area. Ethyl benzoate (E6) shows the highest content, accounting for 0.64% of the total ester peak area. On the other hand, methyl salicate (E7), an ester absent in the honey of sainfoin was found only in carob and astragalus honey (0.06% and 0.75% of the total ester area, respectively) (Table 3). The latter ester is effective in treating muscle pain, back pain, and other rheumatic conditions [95].