Antioxidant Activity and Mineral Content in Unripe Fruits of 10 Apple Cultivars Growing in the Northern Part of Korea

This study evaluated unripe fruits of ten apple cultivars removed during fruit thinning for their antioxidant activity and mineral content. The unripe fruits were collected from Chuncheon and Jeongseon located at Gangwon-Do of Korea. Antioxidant activities such as total phenolic content (TPC), total flavonoid content (TFC), DPPH (2,2-diphenyl-1-picrylhydrazyl) activity, FRAP (Ferric reducing antioxidant power), vitamin C and mineral contents were measured. In the unripe fruits obtained from Chuncheon and Jeongseon, TPC was in the range 8.97–81.4 and 7.11–42.15 mg GAE/g, TFC was in the range 9.38–33.81 and 6.83–19.24 mg QE/g, DPPH was in the range 27.17–82.58 and 29.73–73.24, FRAP was in the range 33.54–371.12 and 26.76–185.69 µM trolox /g, and Vitamin C was in the range 1.1–4.9 and 1.1–2.8 mg/AA/g, respectively. Among the cultivars tested, ‘Hongro’ and ‘Honggeum’ had consistently highest antioxidant activity, while ‘Summer King,’ ‘Tsugaru,’ and ‘Arisoo’ had the lowest value. ‘Picnic’ had the highest mineral contents expect P and K in Joengsoen, while ‘Summer King’ and ‘Tsugaru’ had the lowest value in both locations. These differences could be due to the genetic characteristics and/or their growth environments. These results could provide information to help with better utilization of thinned unripe fruits of apples in Korea.