Browsing by Author "Gafuma, Samuel"

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Influence of key chemical components on hardness of indigenous cooking and juice banana cultivars from Uganda
(Kyambogo University (Unpublished work), 2019-10) Gafuma, Samuel
Bananas undergo significant postharvest losses at the farm, during handling, cooking and serving. Loss of palatability and food mass occurs during serving and consumption due to hardening of cooked banana texture. Texture affects sensory properties of bananas and is very important in determining a good cooked banana. Different banana cultivars differ in hardness and the causes for these differences are not well studied particularly among indigenous cooking and juice banana cultivars grown in Uganda. This study examined influence of key chemical components on hardness of bananas. A total of eleven (11) cooking and three (3) juice banana cultivars grown in and endemic to Uganda, were selected as a case study. Bananas were harvested and used at green mature unripe stage. The samples were analyzed for starch, pectic substances and proximate composition using standard methods, and subsequently assessed the physico-chemical properties of starch and the pectic substances which were the major components. Hardness profile of the 14 banana cultivars was assessed using a texture analyzer. Principle Component Analysis (PCA) revealed that starch and pectic substances were highly and positively correlated with hardness of raw bananas. Then, the role of starch and pectin in influencing hardness of cooked bananas was determined. Sliced bananas were separately treated with pectin, starch and starch-pectin composite before being cooked by steaming combined with mashing and their hardness determined. Pectin was also structurally hydrolyzed from sliced bananas using pectinase (polygalacturonase) and the resulting bananas were cooked in the same way and evaluated for changes in hardness. According to results, water, starch, and pectic substances were the main components of fresh green mature bananas. Juice bananas yielded significantly more dry matter (30 to 33%) than cooking bananas (P<0.05) which yielded 19 - 25.6% dry matter. Juice bananas yielded significantly more starch (19 to 25%) than cooking banana cultivars (P<0.05) which yielded (4 to 15.2% except one cultivar at 21%). Juice banana cultivars also yielded significantly more crude pectic substances (29.7 to 30.5%) than cooking banana cultivars ((7.5 to 21%) (P<0.05). Other chemical components examined included crude ash (1.97 to 4.24%), crude fibre (0.251 to 0.478%), crude protein (1.23 to 5.64%) and crude fat (0.15 to 0.58%) which did not differ significantly between cooking and juice banana cultivars (P>0.05). The physico-chemical properties (i.e. swelling power, solubility, amylose & resistant starch content and pasting
Physicochemical characterization of sugar syrup and ethanol from starch of selected Ugandan-grown cassava and maize varieties
(Food and Humanity, 2026-01-19) Mugampoza, Ediriisa; Bwamiki, Lydia; Gafuma, Samuel; Mukama, Matia
This study investigated the influence of variety and extraction method, on the yield and characteristics of starch, sugar syrup and alcohol from selected maize and cassava varieties grown in Uganda. Starch was extracted from four cassava and maize varieties using wet alkaline method, saccharified to sugar syrup using acid and enzyme methods and then fermented to alcohol. Maize varieties yielded close to twice as much starch as cassava varieties with no significant difference between the local and improved varieties. The most starch yielding maize variety was ‘Hybrid 2115’ (50.83 %) and cassava variety was ‘Mwezi mukaaga’ (29.17 %). Cassava starches had higher amylose content compared to maize starches with all starches classifying as normal starches with 15 – 24 % amylose content. Acid hydrolysis produced averagely higher sugar concentration (20.08 ◦Brix) compared to enzyme hydrolysis (15.21◦Brix). Enzyme hydrolysis gave distillates with comparatively higher ethanol content, in tandem with the observed higher alcohol by volume and fermentation efficiency. The highest ethanol content was from maize ‘Hybrid 2115’ distillate at 40.95 %. Maize varieties ‘Hybrid 2115’ and ‘Longe 4H’ performed best and ‘Mwezi mukaaga’ and ‘Mukumba’ among the cassava varieties. These can be commercialised for hydrolysis and fermentation. While acid hydrolysis produced sugar syrups with the highest sugar concentration, enzyme hydrolysed syrups performed best for fermentation to alcohol.