## 3 Results  
A total of 49 metabolites were identified and quantified from \({}^{1}\)H NMR spectra from both the hydroalcoholic and the chloroform extract. Resonance assignment was carried out on the basis of the signal chemical shift, multiplicity, TOCSY, HSQC, and HMBC correlations. For example, the assignment of chlorogenic acid was initially hypothesized due to the presence, in the \({}^{1}\)H hydroalcoholic spectra, of two doublets at 7.65 and 6.39 ppm, an ABX system at 7.19 (doublet), 7.12 (doublet of doublets), and 6.94 ppm (doublet) and a complex spin system at 5.33, 4.23, 3.88, 2.12, and 2.07 ppm, with the latter two resonances having an area double that of the others. The spin systems were identified due to the correlation among the proton resonances while the connection between the systems was determined by combining the information from HSCQ and HMBC experiments. In greater detail, HSQC provided the resonances of the carbons directly bonded to the observed protons and the HMBC showed the long-range correlations among the systems. Specifically, the HMBC correlation between the proton at 7.65 ppm with the carbon at 40.11 ppm indicated the presence of an ester bond between the caffeoyl and quintic moieties, thus allowing to univocally assign the chlorogenic acid. The particulars of the TOCSY, HSQC, and HMBC experiments concerning chlorogenic acid are reported in Figure 1, while a detail of the TOCSY experiment carried out on chloroform extract is reported in Figure 2 with evidence of the resonances of falcarinol and carotenoids. The \({}^{1}\)H chemical shifts, multiplicity, and the \({}^{13}\)C chemical shifts of the identified molecules are reported in Supplementary Table S1. Figure 1: Details of TOCSY (**A**), HSCQ (**B**), and HMBC (**C**) spectra of the hydroalcoholic extract with evidence of the diagnostic resonances of chlorogenic acid. Figure 2: TOCSY spectrum of the chloroform extract with evidence of the diagnostic resonances of falcarinol and carotenoids. The chosen experimental parameters did not allow to quantify the anthocyanins. In fact, while purple carrots are known to contain anthocyanins acylated with caffeic and other hydroxycinnamic acids [17], the pH of the samples (about pH 6.5) does not allow for their detection due to the short T\({}_{2}\) relaxation time of the diagnostic resonance of the hydrogen in position four of their aglycone moiety [18]. Nevertheless, these experimental conditions were chosen since they allow for the quantifying of a greater number of molecular species due to a reduced superimposition of their diagnostic resonances. To determine the optimum harvest time of purple carrots, a PCA analysis was carried out on the whole data matrix, providing a model whose first six components explained 80% of the overall variance (Figure S1). In this model, a spontaneous grouping of the samples according to their development time was observed, but the analysis of the loadings could not differentiate the processes occurring during the root development from the ones active in late-harvested carrots. As such, two more PCA analyses were performed, one taking into account the carrots harvested during the development months (September, October, and November), and the other was carried out on the profiles of carrots during the late period growth (November and December). The first PC analysis considered carrots from the second to the fourth month of development and provided a model whose first six components explained 80% of the overall variance (Figure 3), with the first component (PC1) accounting for 40% and the second one (PC2) for 12% of the overall variance. Even in this model, a spontaneous grouping of the samples according to their harvest time was evident, and it was possible to determine that PC1 captures variance related to development time. The normalized loading plot of the first component (Figure 4) shows which variables are important along with PC1 factor.