Browsing by Author "Muyanja, CMBK"

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    Nutritional, phytochemical composition and antioxidant activities of the red and white malakwang (hibiscus species) leaves
    (African scholarly science communications trust, 2025-01-29) Ojera, GMA; Magala-Nyago; Byaruhanga, YB; Muyanja, CMBK
    Malakwang (Hibiscus species) is a common vegetable in Uganda diets. This study established the nutritional, phytochemical composition, and antioxidant activities of the red and white malakwang leaves. Malakwang leaves were harvested six weeks after germination. Nutrients and phytochemicals were quantified and qualified using the methods of Association of Official Analytical Chemists (AOAC) and HighPerformance Liquid Chromatography (HPLC). The antioxidant activity was determined using the 2, 2- Diphenyl-1-picrylhydrazyl (DPPH) scavenging method. The quantity of crude fat was significantly higher (p<0.05) in the white malakwang leaf samples (6.9 %) than the red (3.3%). The red had significantly higher (p<0.05) quantities of calcium (1753.6 mg), magnesium (1814.4 mg), iron (233.4 mg), vitamin A (RE) (952.7 µg) and vitamin E (22.8) per 100 g when compared to the 1522.2 mg, 1297.9 mg, 179.7 mg, 857.6 µg, and 16.8 µg, respectively for the white malakwang leaves. The white malakwang leaf samples had higher (p<0.05) quantities of flavonoids (25.7 %) and alkaloids (5.5) than the 20.7 % and 2.1 %, respectively for the red malakwang leaves. The red malakwang leaf extract had more mucilage and coumarin contents than the white malakwang leaves. The white and red leaf extracts scavenged 61.3% and 52.7% of DPPH radicals, respectively, which are similar to the 62.2% scavenged by vitamin C. Malakwang leaves could significantly contribute to dietary intake of crude fibre, essential oil, calcium, magnesium, zinc, vitamin A (RE), C and E and phytochemicals hence suggesting a correlation with the cultural health claims for improving breast milk production, appetite, immunity and healing of sores and wounds. Further studies on the evaluation of nutrients and phytochemicals in malakwang leaves are recommended to approve the results of this study. Experimental trials in humans could be performed to evidence the effect of malakwang leaves on breast milk production and healing of sores and wounds. Also, the determination of essential fatty acids and the effect of preparation and postharvest methods are recommended for further studies.
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    Occurrence of listeria monocytogenes in bulked raw milk and traditionally fermented dairy products in Uganda
    (African Journal of Food, Agriculture, Nutrition and Development., 2011) Mugampoza, D; Muyanja, CMBK; Ogwok, P; Serunjogi, ML; Nasinyama, GW
    Bulked raw milk, locally processed yoghurt (LPY) and Bongo, a traditionally fermented dairy product sold at most informal milk cooling points in Uganda, were assessed for occurrence of Listeria spp. and Listeria monocytogenes. Total plate counts (TPC), holding temperature, pH and titratable acidity were also determined in all the milk products at the point of collection using standard methods. A total of 40 samples of bulked raw milk and 30 for each of LPY and Bongo were examined. Listeria spp. was higher in bulked raw milk than in fermented milk. Listeria spp. were detected in 60% of bulked raw milk, 30% of LPY and 15% of Bongo samples. Bulked raw milk had significantly higher (p<0.05) mean Listeria counts (3.10±0.06 log10 cfu mL-1) than LPY and Bongo, 0.82±0.18 and 0.32±0.18 log10 cfu mL-1, respectively. L. monocytogenes was isolated from 13 % of bulked raw milk, 3.0% of LPY but was not detectable in Bongo. Total plate count was significantly different (p<0.05) among the different milk types studied. Bongo had higher TPC (9.00±0.13 log10 cfu mL-1) than bulked raw milk (8.40±0.11 log10 cfu mL-1) and LPY (7.40±0.13 log10 cfu mL-1). The mean total plate counts (4.90 to 9.00±0.13 log10 cfu mL-1) of the fermented dairy products were within the acceptable limits for human consumption. The TPC for bulked raw milk (8.40±0.11 log10 cfu mL-1) was higher than the recommended values of national and international standards. Temperature, pH and titratable acidity were significantly different (p<0.05) among the different milk types. Holding temperature ranged from 5.40 to 8.60oC, pH was 4.20±0.04 to 6.10±0.04 whereas titratable acidity ranged from 0.22±0.01 to 089±0.01%. Listeria counts were not statistically predictable (p>0.05) from variation in the combined effect of pH, percent titratable acidity and temperature. Results of this study demonstrate a high risk associated with consumption of bulked raw milk and fermented dairy products in due to occurrence of Listeria spp.