Tree Age and Harvesting Season Affected Physico-chemical and Bioactive Compounds of Elite Type of Gunda Gundo Orange (Citrus Spp) in the Northern Ethiopia

Abstract

ABSTRACT Marketability and nutritional content are critical factors that need to be considered when a quality of orange fruit is assessed. Among the many factors affecting orange fruit quality, tree age and harvesting season are crucial once; however, the factors remained unmapped. Thus, this study was aimed to explore quality of orange fruit due to differences in tree age and harvesting season. Three trees age groups (young = 10 to 16, moderate = 20 to 27 and old = greater than 30 years) grown at Gunda Gundo monastery and its surroundings, northern Ethiopia and are harvested in October and December. The physico-chemical and antioxidant contents were characterized during two consecutive years (2017–2018). R software (R version 3.6.2) was used for the analysis. The highest single fruit weight of 218.71 g, peel thickness (3.6 mm) and pH (3.73) were obtained from young tree age in 2017. Total soluble solid of 13.4° Brix was recorded from moderate tree age in 2017, while 13.3° Brix was recorded from older trees of October harvest in 2018. High rag mass of 41.78% in October of 2017 and 38.04% in December of 2018 harvest were obtained from fruits of young trees. High vitamin C (53.95 mg 100 ml−1) and total sugar (11.1%) from the young trees; the highest juice mass (52.04%) from moderate trees age; and the highest phenolic content (9.15 mgGAEg−1), iron-reducing power (54.2 mgAAEg−1), total antioxidant (26.55 mgBHTg−1) and lower DPPH EC50 value (1.5 mg ml−1) from fruits of older tree were obtained. This experimental study results show that old trees age had high antioxidant activity.