## 4 Conclusions  
Storage of fresh-untreated purple carrots at 5 \({}^{\circ}\)C for 21 days resulted in a three times higher content of carotenoid, as well as in the stability of anthocyanin content and antioxidant activity. However, sensorial quality in terms of sugar and organic acid contents and visual appearance showed evident decay of the roots after the storage time. In fact, decrease in the maturity index from 62% to 49% was observed. The treatment of purple carrots with ABA enabled spoilage rate during the post-harvest period to be reduced, which was reflected in a maturity index of 75%. As a consequence, organoleptic properties were preserved over the whole storage period and, therefore, purple carrot shelf-life was extended. However, the natural increase in carotenoids initially observed in untreated carrots was diminished from three times to barely double in ABA-treated samples. Similarly, anthocyanins decreased from 2.23 mg ECGg\({}^{-1}\) DW in fresh-untreated samples to 0.30 mg ECGg\({}^{-1}\) DW in ABA-treated ones instead of maintaining steadiness. Since sensorial quality is imperative to ensure the commercial value of foodstuffs, the aim now is to keep organoleptic characteristic improvement, increasing, in turn, the antioxidant activity with a focus on obtaining a long-lasting functional food. For that purpose, further study, including combination of ABA with other natural phytoregulators (i.e., salicylic acid and/or ethanol), together with a deeper optimization process of the storage conditions, is scheduled. The final intention is to propose exogenously applied natural phytoregulators as a tool for extending purple carrot shelf-life in storage with no need for artificial preservatives.  
Conceptualization, M.L.R.d.C.; Methodology, L.S.-E. and G.P.B.; Validation, G.P.B.; Formal analysis, L.S.-E.; Investigation, L.S.-E. and M.L.R.d.C.; Resources, G.P.B.; Writing--original draft, M.L.R.d.C.; Writing--review & editing, M.L.R.d.C.; Project administration, G.P.B.; Funding acquisition, G.P.B. and M.L.R.d.C. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the Madrid Community and European funding from the FSE and FEDER programs (project S2018/BAA-4393, AVANSECAL-II-CM).  
Not applicable.  
The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.  
[PERSON] thanks Madrid Community for her contract (Call \"Madrid Community INVESTIGO 2022\", Next Generation UE). We are grateful to [PERSON] for her help in performing part of the experimental work.  
The authors declare no conflicts of interest.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \multirow{2}{*}{**Assay**} & \multicolumn{2}{c}{**Fresh-Untreated**} & \multicolumn{2}{c}{**MJ Treatment**} & \multicolumn{2}{c}{**ABA Treatment**} \\ \cline{2-7}  & **On Day 0** & **On Day 21** & **Control** & **Treated** & **Control** & **Treated** \\ \hline DPPH (mg Trolox g\({}^{-1}\) DW) & 12.24 \(\pm\) 0.06 a & 12.71 \(\pm\) 0.05 a & 4.73 \(\pm\) 0.02 b & 4.09 \(\pm\) 0.03 b & 4.25 \(\pm\) 0.02 b & 4.89 \(\pm\) 0.02 b \\ \hline FRAP (mg Trolox g\({}^{-1}\) DW) & 17.57 \(\pm\) 0.08 a & 30.03 \(\pm\) 0.07 a & 7.38 \(\pm\) 0.02 b & 6.02 \(\pm\) 0.02 b & 6.37 \(\pm\) 0.04 b & 7.02 \(\pm\) 0.03 b \\ \hline \end{tabular} Different letters between samples in the same row indicate differences at \(p<0.05\).  
\end{table}
Table 3: Antioxidant activity by DPPH and FRAP assays in fresh-untreated purple carrots and purple carrots treated with MJ and ABA.