Antioxidant Activity of Elderberry Fruits during Maturation

Antioxidant activity (AOA) in fruits of <i>Sambucus nigra</i> and several new elderberry interspecific hybrids involving <i>S. javanica</i> (JA), <i>S. nigra</i> subsp. <i>nigra</i> (NI), <i>S. nigra</i> subsp. <i>nigra</i> ‘Black Beauty’ (BB), <i>S. nigra</i> subsp. <i>cerulea</i> (CER) and <i>S. racemosa</i> (<i>S. racemosa</i> subsp. <i>racemosa</i> (RAC), <i>S. racemosa</i> subsp. <i>racemosa</i> var. <i>miquelii</i> (MIQ), <i>S. racemosa</i> subsp. <i>tigranii</i> (TIG), <i>S. racemosa</i> subsp. kamtschatica—<i>coreana</i> (KOR) at five maturity stages were investigated by applying DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)), FRAP (ferric reducing antioxidant power) and ORAC (oxygen radical absorption capacity) assays. The aim of the study was to compare different assays for estimating AOA in elderberries, to plan the appropriate harvest time and to determine whether the most promising genotypes could be predicted in advance. All assays used showed that AOA increased significantly during maturation. All assays were significantly correlated with each other and could be reliably used for the AOA determination of elderberries. In fully mature berries, significant correlations were also found between total phenolic (TP) content and AOA by all assays, but no significant correlations were found between total ascorbic acid (TAA) content and AOA by all assays. At the fully mature stage, (the most appropriate stage for harvesting), berries of (JA × NI) × BB and (JA × NI) × MIQ were found to be superior in AOA and TP content. Genotypes with higher/lower AOA and TP content could not be predicted in advance, while TAA showed the opposite.