Browsing by Author "Midiwo Jacob"

Now showing 1 - 4 of 4
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    Design Strategy for Effective Passion Fruit Waste Bioconversion with Crude Fungal Enzyme Extracts
    (Biologia, 2023-11) Ojwang Daniel; Obiero George Ogello; Mulaa Francis; Midiwo Jacob
    The objective of this study was to investigate the key factors that influence performance of crude enzyme cocktails in passion fruit peel hydrolysis. Enzyme extracts were obtained from a newly isolated strain of Aspergillus niger KWM. The Box-Behnken Design (BBD) model was developed to determine the optimal conditions for peel hydrolysis. The effect of surfactants and metal ions on the efficacy of enzyme extracts was also investigated. The BBD model predicted maximum galacturonic acid (GalA) yield of 65.3 mg/g at temperature of 50 °C, pH medium of 7.5, substrate loading of 2% (v/v), and an incubation period of 10 h. However, experiments conducted under similar conditions produced GalA that was 2.7% higher than predicted value. Surfactants and metal ions, on the other hand, increased GalA yield even more, with Tween 20 and 2 mM Mg2+ increasing yield by 10.6% (w/v) and 11% (w/v), respectively. The highest GalA yield of 77.8 mg/g dwb or 16% increase, was reported when Mg2+ and Tween 20 were used at a ratio of 0.06. This study revealed that, in addition to optimising key process parameters, the proper proportion of suitable surfactants and metal ions is critical for better performance of crude enzyme cocktails in biomass hydrolysis.
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    Strategies for Improving Hydrolytic Efficiency of Crude Multienzyme Extracts in Mushroom Processing
    (Elsevier Inc, 2022-11) Ojwang D. Otieno; Mulaa F. Jakim; Obiero George; Midiwo Jacob
    The current study investigated and optimized key process parameters affecting mushroom hydrolysis with crude enzymatic extract. The crude enzyme was prepared by solid-state fermentation of pineapple peels using Aspergillus niger. The reaction parameters viz. time, temperature, pH and enzyme concentration were optimized using the central composite design of the response surface methodology. The model predicted glucose yield of 1.49 mg/mL at optimal pH of 6.5, temperature of 50 °C, enzyme loading of 5 % (v/v), and reaction time of 12 h. Mushroom hydrolysis at the same optimal model conditions, increased glucose yield by 10%. More so supplementing SSF media with 0.2% (w/v) Tween-80 and 0.08% (w/v) yeast extract at moisture level of 70–75% significantly (p value < 0.05) improved hydrolytic efficiency of the crude enzyme extract by 2.2-fold. This study provides baseline data that will be useful in developing a low-cost enzyme-based process for hydrolyzing mushrooms to recover high-value products.
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    Utilization of Fruit Waste Substrates in Mushroom Production and Manipulation of Chemical Composition
    (Elsevier B.V, 2022-01) Ojwang D. Otieno; Mulaa Francis J.; Obiero George; Midiwo Jacob
    The current study evaluated the effect of mushroom cultivation using fruit waste substrates on yield performance and antioxidant activities. The total phenolic content and the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities of the mushroom extracts were determined using colorimetric method. Mushroom P. eryngii had the highest yield of 87.2 ± 2.4 g/100 g dry substrate when grown on pineapple peels, while P.ostreatus yielded the least fruiting bodies 53.1 ± 1.8 g/100 g dry substrate when grown on orange peels. Similarly, P. eryngii grown on pineapple peels and P. ostreatus grown on orange peels had the highest and lowest biological efficiencies of 94.2 ± 3.5% and 69 ± 4.3%, respectively. The total phenolic content of P.ostreatus grown on avocado peels was 26.4 ± 3.8 mg GAE/g dry extract, while P.eryngii grown on avocado peels had the lowest at 9.3 ± 0.2 mg GAE/g dry extract. Mushrooms cultivated on fruit wastes generally exhibited higher DPPH activities than those grown on wheat straw (control) substrate. This study provided baseline information on the potential role of fruit waste substrates in mushroom growth and chemical composition.
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    Utilization of Fruit Waste Substrates in Mushroom Production and Manipulation of Chemical Composition
    (Elsevier B.V, 2022-01) Ojwang D. Otieno; Mulaa Francis J.; Obiero George; Midiwo Jacob
    The current study evaluated the effect of mushroom cultivation using fruit waste substrates on yield performance and antioxidant activities. The total phenolic content and the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities of the mushroom extracts were determined using colorimetric method. Mushroom P. eryngii had the highest yield of 87.2 ± 2.4 g/100 g dry substrate when grown on pineapple peels, while P.ostreatus yielded the least fruiting bodies 53.1 ± 1.8 g/100 g dry substrate when grown on orange peels. Similarly, P. eryngii grown on pineapple peels and P. ostreatus grown on orange peels had the highest and lowest biological efficiencies of 94.2 ± 3.5% and 69 ± 4.3%, respectively. The total phenolic content of P.ostreatus grown on avocado peels was 26.4 ± 3.8 mg GAE/g dry extract, while P.eryngii grown on avocado peels had the lowest at 9.3 ± 0.2 mg GAE/g dry extract. Mushrooms cultivated on fruit wastes generally exhibited higher DPPH activities than those grown on wheat straw (control) substrate. This study provided baseline information on the potential role of fruit waste substrates in mushroom growth and chemical composition.