Theses and Dissertations

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Browsing Theses and Dissertations by Author "Beswa, D."

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    The effect of Moringa Oleifera leaves and termite (Isoptera) powders on nutritional and sensory properties of an instant-maize porridge
    (2017-09-18) Netshiheni, Khavhatondwi Rinah; Jideani, A. I. O.; Beswa, D.; Mashau, M. E.
    White maize-based porridge is a staple food for about 80% consumers in South Africa and sub-Saharan African countries contributing significantly to the diet of rural populations in developing countries. White maize is deficient in some amino acids and over-dependency on its porridge may lead to high prevalence of malnutrition-related health conditions. Moringa oleifera (MO) and termite (Isoptera spp.) are known to contain a substantially high amount of protein. The aim of this study was to determine the effect of powders from MO leaves and termite on the nutritional and sensory properties of instant-maize porridge. Inclusion of MO and termite powders in instant-maize porridge, at different treatments, was considered using a completely randomised design. Factor levels were: AOB-control (maize flour); BEA (maize, powders of cooked dried MO and termite); CIA (maize, powders of blanched dried MO and termite) and DJE (maize, powders of uncooked dried MO and termite). Data were analysed using SPSS version 23. The protein content of fortified instant-maize porridge (FMP) significantly (p < 0.05) increased from 10.02 to 21.20% compared to unfortified porridges. The mineral content of FMP was higher in terms of Zn, Fe, Ca and Mg. Moisture content of FMP increased from 5.00 to 6.00%. Sensory analysis showed that among fortified porridges, CIA was rated high for colour and texture, BEA higher in taste and DJE higher for aroma. AOB had higher acceptance than fortified porridges for taste. Powder from MO leaves and termite could be used in complementary foods and food supplements to increase protein and mineral contents.
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    Effects of maturity and processing on quality properties of the watermelon (Citrullus lanatus) fruit juice
    (2019-05-17) Maoto, Makaepea Mossa; Jideani, A. A. O/; Beswa, D.
    Watermelon (Citrullus lanatus) juice is rich in phytochemicals that possess antioxidant properties which are known to have a positive contribution to human health. Colour, pH, total soluble solids, lycopene, β-carotene, ascorbic acid, total polyphenolic content and antioxidants activity are quality properties that characterise watermelon juice. However, these quality properties undergo some chemical changes throughout the stages of maturity of the fruit as well as during thermal processing. The aim of this study was to investigate the effects of maturity and filtration on the physicochemical properties (colour, pH, total soluble solids) and the phytochemicals (lycopene, β-carotene, ascorbic acid, total polyphenolic content and antioxidants activity) of fresh watermelon juice. It further investigated thermosonication effects on these quality properties using response surface methodology (RSM). RSM considering temperature (25 – 52ºC), time (2 – 10 min) and amplitude level (24.1 – 60 μm) at a constant frequency of 20 kHz were the independent variables while colour variables (L*, a* and b*, C* and h*), pH, total soluble solids, lycopene, β-carotene, ascorbic acid, total polyphenolic content and antioxidants activity were the dependent variables. Results showed that colour, pH, total soluble solids, lycopene, β-carotene, ascorbic acid, total polyphenolic content and antioxidants activity of watermelon fruit juice are maturity dependent. All the physicochemical and phytochemical properties increased with maturity. The combination of the CIELAB parameters (L*, a*, b*) was clearly explained by the Chroma (C*) and hue (hº). The (C*) and hº values of the watermelon fruit juice were significantly (p < 0.05) affected by the stages of maturity. The red colour was observed to be more saturated in the fully - ripe sample as indicated by the highest Chroma (7.35) values. The half - ripe sample which was observed to be pink - red had a C* of 5.88 while the lowest (4.32) value was observed from the unripe sample. The highest hº value was obtained from unripe sample (83.89), while lower value was observed from the fully - ripe (76.03) sample because of the saturation of the red colour in the fully - ripe sample. The total soluble solids also increased with stages of maturity 6.66 to 6.60 at half - ripe while at fully - ripe redness changed from 9.3 to 8.99 and TSS 8.37 to 8.02. Filtration has shown a significant (p < 0.05) on the C* and hº values. There was a higher retention of all dependent variables at lower thermosonication treatment (25ºC; 24.4 μm), especially the lycopene which increased by 127%. Model predictions for the colour properties and phytochemicals were closely correlated to the experimental results obtained. Prediction models were found to be significant (p < 0.05) with low standard errors and high coefficients of determination (R2).