Comparative evaluation of petitgrain oils from six Citrus species alone and in combination as potential functional anti-radicals and antioxidant agents*

Six Citrus petitgrain oils, namely C. × sinensis (L.) Osbeck., C. × limon (L.) Osbeck., C. × clementina Hort., C. × aurantium L., C. reticulata Blanco and C. × bergamia Risso & Poit. (P1-P6), were characterized by means of gas chromatography equipped with flame ionisation detector (GC-FID) and gas chromatography coupled to mass spectrometry (GC-MS) and evaluated for their food functional-related properties. Antioxidant and radical-scavenging properties were tested by means of 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, β-carotene bleaching test and Ferric Reducing Antioxidant Power (FRAP) assays. The synergistic interactions on antioxidant efficacy of petitgrain oils in combination were studied. The Relative Antioxidant Capacity Index (RACI) was applied from the perspective of statistics by integrating the antioxidant capacity data determined by all used methods. A high content of monoterpenes and a less representative content of sesquiterpenes characterized Citrus petitgrain oils. In the DPPH assay, C. × aurantium showed major effectiveness with an IC₅₀ value of 27.2 μg/ml. Citrus petitgrains oils, a rich source of healthy phytochemicals, should be considered a by-product of interest.