Browsing by Author "Arnold Katungisa"

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Bioactive compounds and antioxidant activities in peeled and unpeeled sweetpotato roots of different varieties and clones in Uganda
(Future Foods, 2022-12-10) Flora Christine Amagloh; Archileo N. Kaaya; Benard Yada; Doreen Murenju Chelangat; Arnold Katungisa; Francis Kweku Amagloh; Gaston Ampe Tumuhimbise
Rising incidences of non-communicable diseases (NCDs) in Sub-Saharan Africa (SSA) necessitates research into lo- cal functional foods, crucial in managing these conditions. This study aimed to investigate compositional changes in the bioactive compounds and antioxidant activities of peeled and unpeeled roots of Ugandan sweetpotato varieties with different flesh colours using spectrophotometric methods. Bioactive compounds and antioxidant activities, on dry weight basis were significantly higher (P<0.05) in unpeeled than peeled roots. Phenolic com- pounds were significantly higher (P = 0.001) in white, cream, and purple-fleshed roots (59.67–121.04 mg GAE/g) than in yellow and orange-fleshed roots (0.89–10.89 mg GAE/g). The deep orange-fleshed had the highest to- tal carotenoids (averagely 269.82 μg/g) and the white the lowest (averagely 8.36 μg/g). Total alkaloids in the sweetpotato roots ranged between 24.05 and 233.70 μg CE/g, below the potential toxicity range of 3–10 mg/g. The anthocyanin content of purple-fleshed roots was significantly higher (15.29 mg/g; P<0.001) than the other varieties, which ranged between 0.86 and 2.44 mg/g. Principal component analysis showed a stronger relation- ship between phenolics, anthocyanins, tannins, and ABTS radical scavenging antioxidant activity. Vitamin C and total carotenoids were more correlated with FRAP antioxidant activity. Consumption of different sweetpotato varieties with the peels could aid in managing NCDs in SSA.
Breeding Cultivars for Resistance to the African Sweetpotato Weevils, Cylas puncticollis and Cylas brunneus, in Uganda: A Review of the Current Progress
(Insects, 2023-10-25) Benard Yada; Paul Musana; Doreen M. Chelangat; Florence Osaru; Milton O. Anyanga; Arnold Katungisa; Bonny M. Oloka; Reuben T. Ssali; Immaculate Mugisa
In sub-Saharan Africa, sweetpotato weevils are the major pests of cultivated sweetpotato, causing estimated losses of between 60% and 100%, primarily during dry spells. The predominantly cryptic feeding behavior of Cylas spp. within their roots makes their control difficult, thus, host plant resistance is one of the most promising lines of protection against these pests. However, limited progress has been made in cultivar breeding for weevil resistance, partly due to the complex hexaploid genome of sweetpotato, which complicates conventional breeding, in addition to the limited number of genotypes with significant levels of resistance for use as sources of resistance. Pollen sterility, cross incompatibility, and poor seed set and germination in sweetpotato are also common challenges in improving weevil resistance. The accurate phenotyping of sweetpotato weevil resistance to enhance the efficiency of selection has been equally difficult. Genomics-assisted breeding, though in its infancy stages in sweetpotato, has a potential application in overcoming some of these barriers. However, it will require the development of more genomic infrastructure, particularly single-nucleotide polymorphism markers (SNPs) and robust next-generation sequencing platforms, together with relevant statistical procedures for analyses. With the recent advances in genomics, we anticipate that genomic breeding for sweetpotato weevil resistance will be expedited in the coming years. This review sheds light on Uganda’s efforts, to date, to breed against the Cylas puncticollis (Boheman) and Cylas brunneus (Fabricius) species of African sweetpotato weevil.
Development and validation of near-infraredspectroscopy procedures for prediction ofcassava root dry matter and amylose contentsin Ugandan cassava germplasm
(Journal of The Science of Food and Agriculture, 2023-11-23) Ephraim Nuwamanya; Enoch Wembabazi; Michael Kanaabi; Fatumah Babirye Namakula; Arnold Katungisa; Ivan Lyatumi; Williams Esuma; Emmanuel Oladeji Alamu; Dominique Dufour; Robert Kawuki; Fabrice Davrieux
BACKGROUND: Cassava utilization for food and/or industrial products depends on inherent properties of root dry matter con- tent (DMC) and the starch fraction of amylose content (AC). Accordingly, in the present study, near-infrared reflectance spectroscopy (NIRS) models were developed to aid breeding and selection of DMC and AC as critical industrial traits taking care of root sample preparation and cassava germplasm diversity available in Uganda. RESULTS: Upon undertaking calibrations and cross-validations, best models were adopted for validation. DMC in calibration samples ranged from 20 to 45 g 100g−1, whereas, for amylose content, it ranged from 14 to 33 g 100g−1. In the validation set, average DMC was 29.5 g 100g−1, whereas, for amylose content, it was 24.64 g 100g−1. For DMC, a modified partial least square regression model had regression coefficients (R2) of 0.98 and 0.96, respectively, in the calibration and validation set. These were also associated with low bias (−0.018) and ratio of performance deviation that ranged from 4.7 to 5.0. In addition, standard error of prediction values ranged from 0.9 g 100g−1 to 1.06 g 100g−1. For AC, the regression coefficient was 0.91 for the calibration set and 0.94 for the validation set. A bias equivalent to −0.03 and a ratio of performance deviation of 4.23 were observed. CONCLUSION: These findings confirm the robustness of NIRS in the estimation of dry matter content and amylose content in cassava roots and thus justify its use in routine cassava breeding operations.
Household Processing Methods and Their Impact on Bioactive Compounds and Antioxidant Activities of Sweetpotato Genotypes of Varying Storage Root Flesh Colours
(Antioxidants Journal, 2022-09-21) Flora C. Amagloh; Archileo N. Kaaya; Gaston A. Tumuhimbise; Arnold Katungisa; Francis K. Amagloh; Benard Yada
Sweetpotato storage roots, peeled and unpeeled, of varying flesh colours (white, cream, yellow, pale orange, deep orange, and purple) were spectrophotometrically evaluated for their bioac- tive compounds and antioxidant activities. Roots were boiled, steamed, baked, fried, or microwaved. The unpeeled roots had relatively higher (p < 0.001) bioactive compounds and antioxidant activ- ities than the peeled ones. All cooking methods increased phenolic compounds, flavonoids, and tannins in all genotypes. Significant losses of total carotenoids occurred with all cooking methods (ranging from 24.18 to 172.76 μg/g in raw sweetpotatoes vs. 10.06 to 118.17 μg/g in cooked ones; p < 0.001), except the deep-orange-fleshed genotype, in which frying slightly increased carotenoids from 269.81 to 304.74 μg/g. Microwaving retained 69% vitamin C in the cream-fleshed one, the high- est among the cooking methods. Anthocyanins decreased with baking and frying in the purple-fleshed one but increased with other methods; microwaving being highest at 13.9% (17.43 mg/g). While the 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid antioxidant activity decreased with all cooking techniques in some genotypes, ferricyanide-reducing antioxidant potential increased. The retention of bioactive compounds in sweetpotato storage roots depends on the processing method. Thus, to obtain the most health benefits, consumers should use different cooking methods but retain the peels.