## 2 Results and Discussion
In the case of the stages of maturation in the Frontera variety, this is similar to the Albion variety. In Figure 1c, it is evident that the last stage of maturation (FR6) is alone on the classification tree, which indicates that in this variety, the VOCs related to aroma reach their maximum when the fruit surface is 100% red and 43-44 days have passed since anthesis; at the same time, the chemical family with the highest positive correlation is the esterified COVs, which as mentioned above, are the most representative of mature fruits [1]. To distinguish the most important metabolites for each variety during the maturation process, variable importance in the projection (VIP) graph was used. VIP is a weighted sum of the squares, it takes into account to count the amount of variation Y-explained. Higher VIP scores show the metabolites that had a higher level of importance within each variety. The generated VIP graph classified the individual metabolites by their ability to separate the maturation stages in each variety, respectively. In Figure 2a, it can be observed that for the latest maturation stages of the Albion variety, the compound with the strongest positive correlation was hexanoic acid methyl ester, which belongs to the chemical family of the esters. This family is one of the most influential in terms of the characteristic aroma of strawberries, so it can be inferred that this compound can be used as a volatile marker for determining the optimal maturation stage for the Albion variety [35]. On the other hand, hexanoic acid methyl ester showed a negative correlation with respect to fruit in initial stages, and the compound that was most representative of these stages of maturation was octylcyclohexane, which belongs to the family of the alkanes, which are closely associated with the herbaceous aromas of immature fruits [24]. Figure 2: Variable importance in projection (VIP) graph showing the 15 most important VOCs in descending order. The degree of importance during each phenological stage is shown by the color gradient, in which red indicates a high correlation and green a low correlation. VIP score is a measure of a variable’s importance. (**a**) VIP var. Albion; (**b**) VIP var. Festival; (**c**) VIP var. Frontera. For the Festival variety, hexanoic acid methyl ester was the most representative compound for the latest stages of maturation (FE4, FE5, and FE6), making it potentially useful as an indicator of maturity for this variety, while heptylcyclohex was the most representative of the initial stages (FE0 and FE1). This is similar to the report by [PERSON] and [PERSON] [21] that hexanoic acid methyl ester is one of the main VOCs involved in the aroma of mature strawberry, and therefore, that hexanoic acid methyl ester can be used as a volatile marker to identify the degree of maturity in strawberry fruits of the Festival variety (Figure 2b). In the case of the Frontera variety, the compound most strongly associated with the latest stages of maturation (FR4, FR5, and FR6) was butanoic acid methyl ester, which belongs to the ester family and, like in the previous cases, is characteristic of mature fruit, it has been mostly reported in strawberry and is characterized by the fruity aromatic note and therefore this compound could be an indicator of optima maturation in the Frontera variety [20] (Figure 2c). Taken together, the univariate and multivariate statistical analyzes show that, despite the significant variability between the volatile profile at each stage of maturation, a proportion of the metabolic variability between strawberry varieties is conserved from one variety to another, as determined by established based on metabolite profiles. The reason for this is not clear, but it may have something to do with the particular characteristics that each variety presents. The most interesting fact is that evidence was found that there are differences in the maturation process between strawberry varieties, examining their volatility profile at each stage of maturation.