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 profile 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 season 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.
Wang, Y., Ji, S., Zang, W., Wang, N., Cao, J., Li, X., et al. (2019) Identification of Phenolic Compounds from a Unique Citrus Species, Finger Lime (Citrus australasica) and Their Inhibition of LPS-Induced NO-Releasing in BV-2 Cell Line. Food and Chemical Toxicology, 129, 54-63. https://doi.org/10.1016/j.fct.2019.04.006
[3]
El-Otmani, M., Ait-Oubahou, A. and Zacarías, L. (2011) Citrus spp.: Orange, Mandarin, Tangerine, Clementine, Grapefruit, Pomelo, Lemon and Lime. In: Yahia, E.M., Ed., Postharvest Biology and Technology of Tropical and Subtropical Fruits, Elsevier, 437-514, 515e-516e. https://doi.org/10.1533/9780857092762.437
[4]
Turan, M. and Mammadov, R. (2021) Overview of Characteristics of the Citrus Genus in Overview on Horticulture. IKSAD, 34 p.
[5]
Kongai, H., Mangisoni, J., Elepu, G., Chilembwe, E. and Makoka, D. (2018) Analysis of Citrus Value Chain in Eastern Uganda. African Crop Science Journal, 26, 417-431. https://doi.org/10.4314/acsj.v26i3.7
[6]
Plan for Modernisation of Agriculture (PMA) (2009) Citrus Market Study Report for Teso Sub-Region. Ministry of Agricultural Animal Industry and Fisheries.
[7]
Kongai, H., Mangisoni, J., Elepu, G., Chilembwe, E., Kwapata, M.B. and Makoka, D. (2011) Analysis of Citrus Value Chain in Kyoga Plains Agricultural Zone in Uganda. African Crop Science Conference Proceedings, 10, 19-21.
[8]
Uganda Development Cooperation (UDC) (2015) Improving Production and Marketing of High Quality Citrus and Mango Fruits in Teso Sub-Region. Korea International Cooperation Agency (KOICA).
[9]
Zekri, M. (2011) Factors Affecting Citrus Production and Quality. Trees.
[10]
Albrigo, L.G. (2004) Climatic Effects on Flowering, Fruit Set and Quality of Citrus—A Review. Proceedings of the International Society of Citriculture X Congress, Agadir, 15-20 February 2004, 1255.
[11]
Seminara, S., Bennici, S., Di Guardo, M., Caruso, M., Gentile, A., La Malfa, S., et al. (2023) Sweet Orange: Evolution, Characterization, Varieties, and Breeding Perspectives. Agriculture, 13, Article No. 264. https://doi.org/10.3390/agriculture13020264
[12]
Lado, J., Rodrigo, M.J. and Zacarías, L. (2014) Maturity Indicators and Citrus Fruit Quality. Stewart Postharvest Review, 10, 1-6.
[13]
EU (2011) Reglamento de ejecución (UE) Nº 543/2011 de la Comisión de 7 de junio 2011. Official Journal of the European Union, L157, 71-75.
[14]
US EAS (2022) US EAS 330:2022 Citrus Fruits-Specification.
[15]
Adriko, J., Semalulu, O., Tinyiro, E., Otim, A., Makhosi, P., Acom, G., Neumbe, D., Obongo, I., Taeson, P., Nampamya, D., Hyun, D. and Driciru, P. (2021) Citrus Pro-duction Manual: A Guide for Establishment and Management of a Citrus Orchard. KOPIA Uganda Center, 50 p.
[16]
Climate Engine (2024) Desert Research Institute and University of California.
[17]
Shravan, R. and Shere, D.M. (2018) Study of Physico-Chemical Characteristics of Sweet Orange (Citrus sinensis) Fruit. Journal of Pharmacognosy and Phytochemistry, 7, 1687-1689.
[18]
Nawaz, R., Abbasi, N.A., Ahmad Hafiz, I. and Khalid, A. (2020) Impact of Climate Variables on Fruit Internal Quality of Kinnow Mandarin (Citrus nobilis Lour X Citrus deliciosa Tenora) in Ripening Phase Grown under Varying Environmental Conditions. Scientia Horticulturae, 265, Article ID: 109235. https://doi.org/10.1016/j.scienta.2020.109235
Domingues, E.T., Tulmann Neto, A., Pompeu Junior, J., Teófilo Sobrinho, J., Mat-tos Junior, D. and Figueiredo, J.O. (2003) Selection of Orange Varieties with Regard to Fruit Quality and Maturation Period. Orange, Cordeirópolis, 24, 471-480.
[21]
Hussain, S., Curk, F., Anjum, M.A., Pailly, O. and Tison, G. (2013) Performance Evaluation of Common Clementine on Various Citrus Rootstocks. Scientia Horticulturae, 150, 278-282. https://doi.org/10.1016/j.scienta.2012.11.010
[22]
Matheyambath, A.C., Padmanabhan, P. and Paliyath, G. (2016) Citrus Fruits. In: Encyclopedia of Food and Health, Elsevier, 136-140. https://doi.org/10.1016/b978-0-12-384947-2.00165-3
[23]
Oliveira, V.d.S., Zucoloto, M., Ferreira, L.d.S., Barbosa, D.H.S.G., Soares, W.d.S. and Passos, O.S. (2023) Physico-Chemical Characterization of Orange Fruits on Different Rootstocks. Revista Brasileira de Fruticultura, 45. https://doi.org/10.1590/0100-29452023814
[24]
Beber, P.M., Álvares, V.d.S. and Kusdra, J.F. (2018) Qualidade industrial e maturação de frutos de laranjeiras-doce em Rio Branco, Acre. Citrus Research & Technology, 39, 1-9. https://doi.org/10.4322/crt.10317
[25]
Sau, S., Ghosh, S.N., Sarkar, S. and Gantait, S. (2018) Effect of Rootstocks on Growth, Yield, Quality, and Leaf Mineral Composition of Nagpur Mandarin (Citrus reticulata Blanco.), Grown in Red Lateritic Soil of West Bengal, India. Scientia Horticulturae, 237, 142-147. https://doi.org/10.1016/j.scienta.2018.04.015
[26]
Farag, M.A., Abib, B., Ayad, L. and Khattab, A.R. (2020) Sweet and Bitter Oranges: An Updated Comparative Review of Their Bioactives, Nutrition, Food Quality, Therapeutic Merits and Biowaste Valorization Practices. Food Chemistry, 331, Article ID: 127306. https://doi.org/10.1016/j.foodchem.2020.127306
[27]
Sarkar, T. and Mani, A. (2018) Maturity Indices of Tropical and Sub-Tropical Fruit Crops.
[28]
de Siqueira, D.L. and Salomão, L.C.C. (2017) Citrus from Planting to Harvest. Editora UFV, 278 p.
[29]
Buffon, S.B., Zucoloto, M., Passos, O.S., Barbosa, D.H.S.G., Altoé, M.S. and Morais, A.L.d. (2021) Initial Production and Fruit Quality of Fifty-Seven Sweet Orange Varieties on Four Rootstocks in Southern State of Bahia. Revista Brasileira de Fruticultura, 43. https://doi.org/10.1590/0100-29452021765
[30]
Mbogo, G.P., Mubofu, E.B., Othman, C. and e, C. (2010) Post Harvest Changes in Physico-Chemical Properties and Levels of Some Inorganic Elements in off Vine Ripened Orange (Citrus sinensis) Fruits Cv (Navel and Valencia) of Tanzania. African Journal of Biotechnology, 9, 1809-1815. https://doi.org/10.5897/ajb10.1781
[31]
Rodrigues, M.J.d.S., Andrade Neto, R.d.C., Araújo Neto, S.E.d., Soares Filho, W.d.S., Girardi, E.A., Lessa, L.S., et al. (2019) Performance of “Valência” Sweet Orange Grafted onto Rootstocks in the State of Acre, Brazil. Pesquisa Agropecuária Brasileira, 54. https://doi.org/10.1590/s1678-3921.pab2019.v54.01349
[32]
Liu, Y., Heying, E. and Tanumihardjo, S.A. (2012) History, Global Distribution, and Nutritional Importance of Citrus Fruits. Comprehensive Reviews in Food Science and Food Safety, 11, 530-545. https://doi.org/10.1111/j.1541-4337.2012.00201.x
[33]
Pao, S. and Fellers, P.J. (2003) Oranges. In: Caballero, B., Trugo, L. and Finglas, P., Eds., Encyclopedia of Food Sciences and Nutrition, Elsevier, 1,341-1,346.
[34]
Topuz, A., Topakci, M., Canakci, M., Akinci, I. and Ozdemir, F. (2005) Physical and Nutritional Properties of Four Orange Varieties. Journal of Food Engineering, 66, 519-523. https://doi.org/10.1016/j.jfoodeng.2004.04.024
Mira-García, A.B., Conejero, W., Vera, J. and Ruiz-Sánchez, M.C. (2023) Effect of Water Stress and Shading on Lime Yield and Quality. Plants, 12, Article No. 503. https://doi.org/10.3390/plants12030503
[37]
Zhang, J. and Ritenour, M.A. (2016) Sugar Composition Analysis of Commercial Citrus Juice Products. Proceedings of the Florida State Horticultural Society, 129, 178-180.
