Phytochemicals and antioxidant activity of different apple cultivars grown in South Ethiopia: case of the wolayta zone

Abstract

Apple fruit is one of the most intensively grown and widely cultivated fruit crop in the temperate regions around the world. This study investigated sugar, vitamin C, total phenolic contents (TPC), total flavonoid contents (TFC), and antioxidant activity of three varieties (Golden delicious, Fuji rose, and Granny smith) of whole apple fruits (peel and flesh). Total sugar, reducing sugar and sucrose contents were determined by Lane and Enyon method. Folin-Ciocalteu and aluminum chloride, and standardized iodine solutions were used to determine TPC, TFC, and vitamin C, respectively. Antioxidant activity was determined using 2, 2-Diphenyl-1-Picryl-Hydrazyl (DPPH) scavenging, total antioxidant and ferric ion reducing power assays. It was found that Golden delicious cultivar contained the highest amount of total sugar (17.32 ± 0.40 mg/100 g juice) and reducing sugar (10.04 ± 0.30 mg/100 g juice), whereas the juice of Fuji rose variety had the highest amount of sucrose (6.90 ± 0.35 mg/100 g of juice). The Granny Smith variety had the highest TPC (71.88 ± 2.30 mg gallic acid equivalent per gram of dried extract) whereas the Fuji rose had the highest TFC (21.91 ± 2.55-mg catechin equivalent per gram of dried extract). The Golden delicious cultivar had the highest vitamin C (31.48 ± 2.18 mg/100 g of juice). The Fuji rose showed the strongest DPPH radical scavenging activity (EC50 = 86.20 ± 2.28 µg/mL), iron reducing power (EC50 = 1.93 ± 0.66 mg/mL), and total antioxidant activity (0.46 ± 0.08 mg butylated hydroxy toluene equivalent/g of dried extract). Based on the present investigation, it can be concluded that the significant differences in the phytochemical composition and antioxidant activity of apple fruits could be attributed to varietal differences.

Keywords

• antioxidant activity
• apple
• dpph
• phytochemicals
• phenolics