## 4 Discussion
Thus, strawberry aroma is the result of the combined perception of many aromatic constituents [21]. The volatile profile of strawberries was in line with recent research [41; 42; 43]. As reported by other authors, there are considerable differences in the volatility of different varieties of strawberry [43]. The 'Clery' variety selected for this study is highly valued for its flavour, which is similar to the 'Gariguette' variety, included in the study by [PERSON] et al. [41]. It is important to emphasize that aromadoes not necessarily depend on the quantitative concentration of a volatile compound. Compounds that have highly significant concentrations may have no significance for aroma, and conversely, compounds that are only present in trace amounts may be the key components in the overall aroma profile [41]. On the other hand, it is necessary to understand that the concentration of certain flavours is an important factor in achieving flavour consistency and that a small change in concentration could alter certain flavour types [44]. The aldehyde (E)-2-hexen-1-al was the most abundant individual volatile compound in the strawberries. Hexanal and (E)-2-hexen-1-al are described as less pleasant green, leafy and grassy sensory notes typical of unripe fruits. They are present in higher concentrations in green fruits and decrease during ripening [45]. In this study, we recorded a significant influence of fertilisation on the content of hexanal and (E)-2-hexen-1-al. Many studies have demonstrated that aldehyde concentrations increased with increased N and Ca fertilisation [46]. Our results were also in agreement with [PERSON] et al. [3], who demonstrated higher hexanal and (E)-2-hexen-1-al content in strawberries fertilised with N in their research. The authors explained that the increase in the unpleasant aroma compound is due to a delay in maturation. However, in our case, we sampled only fully mature red fruits, and the aldehyde content did not decrease with maturation. Fertilisation could have affected enzyme lipoxygenase (LOX) activity or caused a change in the content of linoleic acid--hexanal precursor via the LOX pathway [47]. Fertilisation had a positive impact on aroma due to increased content of esters, which contribute to a pleasant aroma profile. Although over 360 compounds have been identified in the aroma of strawberries, primarily methyl and ethyl esters appear to contribute most to a pleasant strawberry aroma [48]. The increase in both aldehyde and ester content could be explained by the fact that aldehydes are derived directly from the lipoxygenase pathway (LOX)-derived fatty acids as mentioned above, and further serve as precursors in the formation of esters [44]. Ketone 2-heptanone, with its intense fruity and flowery flavour, has an important impact on strawberry aroma [41]. It is widely used as a fragrance in cosmetics and as a flavouring agent in foodstuffs. Ketone content is very important and contributes to the acceptance and likeability of certain strawberry cultivars. The chemical class of terpenes and alcohols in strawberries has been of particular interest, since these compounds, like ketones, provide the fruity and flowery fragrance [41] and are also known to exert biological activity against fungal and bacterial microorganisms [44]. Terpenoids, especially geraniol, \(\alpha\)-terpineol and meridolol, are responsible for the floral aroma and flavour of strawberries [49]. Nitrogen-fertilised fruits contained lower amounts of pleasant aromas (geraniol and \(\alpha\)-terpineol) and consequently had a less pleasant flavour. It is possible that this might be one of the reasons why plants fertilised with N are more susceptible to infections [50]. In addition, calcium-treated fruits contained significantly higher amounts of these important terpenoids in comparison to nitrogen-fertilised plants. Moreover, a recent study has shown that terpenoids such as meridolol have health benefits in terms of anti-inflammatory, antioxidant, antinociceptive, anticancer and anti-obesity properties [51; 52].