Total phenolics, organic acids, sugars and antioxidant activity of mandarin (Citrus clementina Hort. ex Tan.): Variation from rootstock

• It has been examined the influence of fourteen citrus rootstocks on the bioactive constituents of ‘Clemenules’.
• The antioxidant activity and total phenolic results were affected considerably by the rootstock.
• Given the differences on bioactive compounds, these parameters should be included as an important factor in future breeding program.

The objective of this study was to evaluate and compare ‘Clemenules’ mandarin on fourteen rootstocks: ‘Carrizo’ citrange, ‘Swingle’ citrumelo, ‘Cleopatra’ mandarin, Macrophylla, Volkameriana, C-35 and eight new hybrids rootstocks developed at the Instituto Valenciano de Investigaciones Agrarias in Valencia, Spain. Some organoleptic and nutritive parameters related to fruit quality (total soluble solids, total acidity, organic acids and sugars), the content of bioactive compounds (total phenolics) as well as the total antioxidant activity (TAA) due to hydrophilic (H-TAA) and lipophilic (L-TAA) compounds have been determined in Clementine juices. Results showed that rootstock plays an important role in determining the organoleptic and nutritive quality, as well as the concentration of bioactive compounds. Ripening index ranged from 16.9 to 24.2 and total acidity from 5.19 to 8.37 g citric acid L−1. The major organic acids detected were citric and tartaric acids and they varied among rootstocks too. Sucrose was the main sugar for all rootstocks. The antioxidant activity and total phenolic results were affected considerably by the rootstock. Given the differences on bioactive compounds concentration and antioxidant activity between rootstocks, these parameters should be included as an important factor in future breeding program to obtain new scion-stock combinations with enhanced bioactive compounds.