Seasonal Fruit Quality Profile of Three Orange Varieties in Teso Subregion—Eastern Uganda

Abstract

Teso subregion in Eastern Uganda is a leading production hub for citrus in Uganda. However, information on fruit quality profile of the three major varieties (Hamlin, Valencia and Washington navel) grown in this region was limited and/or unreported, partly resulting in their limited use for industrial processing. The current study sought to understand the seasonal quality pro- file of these varieties during the wet and dry seasons for the years 2019, 2022 and 2023. The study was conducted with farmers in the districts of Kumi, Ngora, Soroti and Kalaki. Mature green oranges were periodically harvested and analysed for physical and chemical properties. The results showed that the quality of oranges varied depending on the season at harvest and the variety with significant differences (p ≤ 0.05). Mean weight per fruit was highest in wet season Washington navel (277.5 g) and lowest in dry season Hamlin (149.3 g). Similarly, fruit size varied in the wet season where Washington navel (81.2 mm) had the biggest fruits while dry season Hamlin were smallest (66.6 mm). Dry season Washington navel had had the thickest peel (7.9 mm). Valencia from the wet season had the highest juice content (36.9%) compared to Washington navel (26.5%) from the dry season with the lowest. Titratable acidity was higher in the dry season Valencia (0.9%) compared to the wet sea- son Washington navel and Hamlin (0.3%). Similarly, Total soluble solids (TSS) was higher in the dry season (Washington navel, 10.1 ̊Brix) in contrast to the wet season (Hamlin and Valencia, 7.7 ̊Brix). Valencia had the lowest pH (3.1) however, pH did not vary significantly between season for each variety except for Hamlin. Vitamin C content was higher during the dry season led by Valencia (57.6 mg/100g) and Hamlin (57.4 mg/100g). Sugar to acid ratio was highest during the wet season (Washington navel, 41.5) and lowest in the dry season (Valencia, 17.1). Overall, dry season fruits and more especially Valencia showed versatility in meeting most of the quality requirements for both industrial juice processing and the fresh market. However, there is need to improve the available orange varieties with regard to juice content and optimal sugar: acid ratio regardless of season.