Ascorbic Acid Content and Antioxidant Activity of Juice in Various Citrus Accessions

Abstract

Specific and varietal differences of ascorbic acid (AsA) concentration and DPPH radical scavenging activity of citrus juice citrus were investigated. In 2006-2007, 41 species and/or cultivars (accessions) were used as materials. Their AsA concentrations ranged from 8.2 mg·100 mL⁻¹ (Shiikuu) to 50.0 mg·100 mL⁻¹ (‘Amakusa’); the average was 26.6 mg·100 mL⁻¹. Their DPPH radical scavenging activity ranged from 0.64 nmol-Trolox equivalent·μL⁻¹ (Shiikuu) to 3.49 nmol (‘Amakusa’); the average was 1.96 nmol. There was a high positive correlation between AsA concentration and DPPH radical scavenging activity (r = 0.859 (significance at the 1% level)). Correlation coefficient between AsA concentration and DPPH radical scavenging activity of 2006–2007 and those of 2007–2008 were r = 0.843 (significance at the 1% level) and r = 0.951 (significance at the 1% level), respectively in juice of 13 accessions. Seasonal change in the AsA concentration in juice and DPPH radical scavenging activity using ten accessions was investigated in 2007–2008. AsA concentration of six accessions increased during fruit maturation, but that of three accessions was decreased. In particular, a remarkable increase of Keraji and decrease of Sakurajima komikan and ‘Nova’ was observed in their AsA concentration. DPPH radical scavenging activity was increased in general during fruit maturation, and the activity in January was higher than that in October in eight accessions. Increase of this activity was very rapid in Keraji and ‘Shiranui’.