# Changes in Elderberry (_Sambucus nigra_ L.) Juice Concentrate Polyphenols during Storage
## 4 Conclusions  
The storage at low temperature (5 \({}^{\circ}\)C) was shown to be important to minimize anthocyanin degradation and maintain the color attributes of elderberry juice concentrates. At 5 \({}^{\circ}\)C there was a loss of 22% and 14% (concentrate I and II) in total monomeric anthocyanins, while at room temperature, losses of 67% and 71% were observed. At the same time, the percent polymeric color increased, especially at room temperature, which indicates that anthocyanins may be involved in polymerization reactions. The analysis of individual phenolic compounds showed that cyanidin-3-O-sambubioside and cyanidin-3-O-glucoside degraded in higher proportion than cyanidin-3-O-globucoside and cyanidin-3-O-sambubioside-5-O-glucose. At room temperature, cyanidin-3-O-sambubioside and cyanidin-3-O-glucose degraded faster in the concentrate that was not subjected to the additional heating step during the technological processing. Thus, the thermal treatment of the mask at 80 \({}^{\circ}\)C prior to pressing appears to have a beneficial effect on the conservation of anthocyanins during storage at room temperature.  
The total phenolic content and the in vitro ABTS\({}^{\bullet+}\) antioxidant capacity were relatively stable over storage, suggesting that elderberry concentrates may still preserve their health benefits after seven months of storage.  
Conceptualization, C.M.B.N., A.P., F.G. and D.F.W.; methodology, C.M.B.N., A.P. and D.F.W.; investigation, C.M.B.N., F.G. and D.F.W.; writing--original draft preparation, C.M.B.N.; writing--review and editing, A.P., F.G. and D.F.W.; supervision, D.F.W. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the FEDER, within the PT2020 Partnership Agreement and Compete 2020, grant number POCI-01-0247-FEDER-033558.  
Not applicable.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Sample** & **Mesophiles at 30 \({}^{\circ}\)C (CFU mL\({}^{-1}\))** & **Fungi (CFU mL\({}^{-1}\))** \\ \hline Concentrate I before storage & \textless{}1 & \textless{}1 \\ \hline Concentrate I stored at 5 \({}^{\circ}\)C & \textless{}1 & \textless{}1 \\ \hline Concentrate I stored at room temperature & \(2.1\times 10^{2}\) & \textless{}1 \\ \hline Concentrate II before storage & \textless{}1 & \textless{}1 \\ \hline Concentrate II stored at 5 \({}^{\circ}\)C & \(2.2\times 10\) & \(1.0\times 10\) \\ \hline Concentrate II stored at room temperature & \(1.1\times 10^{3}\) & \(1.1\times 10^{4}\) \\ \hline \hline \end{tabular}
\end{table}
Table 3: Results of microbial counting obtained for concentrates before storage and after five months of storage.  
**Acknowledgments:** Thanks are due to the Polytechnic Institute of Viseu and to FCT/MEC for the financial support to CERNAS-IPV, LAQV-REQUIMUTE (UIDB/50006/2020) and CITAB (UIDB/04033/2020) research units, through national funds, and the co-funding by the FEDER, within the PT2020 Partnership Agreement and Compete 2020. The authors thank the financial support of the Project BagConValor--Criacao de valor no processo tecnologico de producao de sumo concentrado de baga de sabugeiro (POCI-01-0247-FEDER-033558).  
**Conflicts of Interest:** The authors declare no conflict of interest.