Antibacterial and antifungal effect of moringa (Moringa oleifera) seedmeal on marinated smoked African mud catfish (Clarias gariepinus)

The study assessed the antibacterial and antifungal effect of Moringa oleifera seed marinade on smoked Clarias gariepinus stored at ambient temperature for 15 days. Sixty C. gariepinus (15 kg) were gutted, washed, and randomly assigned in triplicate to five treatments containing 0, 5, 10, 15, and 20 g/kg M. oleifera seedmeal in 3.67 g/kg brine solution for 2 hr and later hot smoked for 24 hr. After smoking, the fishes were allowed to cool and packed separately in a transparent Ziploc polythene bag arranged in a box and kept at room temperature. Microbial load and diversity were conducted in the laboratory at 5 days intervals. The fungi isolated were Aspergillus flavus, Aspergillus niger, Saccharomyces cerevisiae, Alternaria alternata, Penicillium citrinium, Neurospora crassa, and Rhizopus stolonifer while Enterobacter spp., Staphylococcus spp., Proteus spp., Streptococcus spp., and Bacillus spp. were the identified bacteria. The optimum effective concentration of moringa seed marinade that acts as anti-bacteria was found best to be 11.2 g/kg of fish moringa marinade. While 12.08 g/kg exhibited the highest anti-yeast effect in C. gariepinus and 10.6 g/kg serves as antifungi. Thus, moringa seed marinade is safe to use as a natural edible food preservative that can protect smoked dried catfish from microbial spoilage.     

Prospects of conducting polymer and graphene as counter electrodes in dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) garner considerable research interest because of high photo-to-electric conversion efficiencies at low production cost. Platinum has been reported as an efficient metal as a counter electrode (CE) in DSSCs for its outstanding electro catalytic performance. However, the high cost and susceptibility to corrosion of Pt are paving the way for exploring new materials to replace Pt as a counter electrode in DSSCs. Various conducting polymers, graphene and conducting polymer-graphene nanocomposites have been found as counter electrodes in DSSCs with remarkable photovoltaic performances. The urge to produce composites or hybrids with nanomaterials is derived from the improvement of photovoltaic performances. This review will focus on the unique physical and chemical properties of conducting polymers and graphene, their individual photovoltaic performances as counter electrodes in DSSCs, followed by the synergistic effect of conducting polymers and graphene in conducting polymer-graphene nanocomposites as counter electrodes in DSSCs. Finally a brief outlook is provided to improve the photovoltaic performance of DSSCs using conducting polymers and graphene-based counter electrodes.     

The pasting,chemical and sensory properties of biofortified cassava root starch-based custard powder

The effect of biofortified cassava root starch (YfCRS) (90–98 %) and whole egg powder (WEP) (2–10 %) on the pasting, chemical and sensory properties of cassava starch-based custard powder (CbCP) were studied using response surface methodology. The result revealed that there are variations in the pasting properties of the CbCP notwithstanding the levels of WEP inclusion, and all the custard powder could form paste below the boiling point of water at the peak time of <5 min. Additionally, the CbCP with high quantity of WEP had the highest protein (6.39 %), iron (29.39 mg/kg) and zinc (4.25 mg/kg) contents, but with low amylose (18.68 %) and trans-β-carotene (0.0756 μg/g) contents. The YfCRS increased the amylose and trans-β-carotene contents of the custard powder. The models for the responses were highly adequate (R² > 80 %), except for peak viscosity, pasting temperature, hydrogen cyanide and overall acceptability. Although all the sensory attributes of the formulated CbCP gruel fall within the likeness range, 93.13 % YfCRS and 7.56 % WEP is the optimum combinations for good quality CbCP. Therefore, to replace maize starch with cassava starch in the production of a quality CbCP, 93.13 % YfCRS and 7.56 % WEP could be used.     

Understanding cassava varietal preferences through pairwise ranking of gari-eba and fufu prepared by local farmer–processors

Within communities in Osun and Imo States of Nigeria, farmer–processors grew and processed a diverse set of improved and landrace cassava varieties into the locally popular foods, gari, eba and fufu. Local and 15 main varieties were grown in a ‘mother and baby trials’ design in each state. Mother trials with three replications were processed by farmer–processors renown in their community for their processing skills. Baby trials were managed and processed by other farmer–processors. The objective was to identify food quality criteria to inform demand-led breeding to benefit users, especially women, given their key roles in processing. Farmer–processors evaluated the overall quality of fresh roots and derived food products through pairwise comparisons. Improved varieties had higher fresh and dry root yield. Overall, landraces ranked first for quality of gari and eba, but several improved varieties were also appreciated for good quality. Landraces in Osun had higher gari yield and a higher swelling power compared to improved varieties. Colour (browning), bulk density, swelling power, solubility and water absorption capacity were the criteria most related to food product ranking by farmer–processors. Evaluation of varieties under farmer–processors’ conditions is crucial for providing guidance to breeders on critical selection criteria.     

A review of cassava semolina (gari and eba) end-user preferences and implications for varietal trait evaluation

The purpose of this review is to support breeders and food scientists by examining research carried out on end-user preferences for gari and its derived dough product, eba, in Africa. The review focused on gari regarding the physical and chemical composition of raw cassava roots, methods of storage, the composition of gari with or without enrichment, and the sensory evaluation of gari and eba. The primary sensory attributes identified to describe gari are colour, taste, texture, aroma and flavour. Texture attribute of importance is crispiness for uncooked gari, and hand feel before consumption for eba. There was a significant correlation between the sensory characteristics of gari and the starch and cyanogenic potential (CNP) contents of the raw roots. Hence, the correlation of the end-user preferences with the chemical composition of the cassava roots could be helpful to breeders in refining selection criteria and developing high-throughput screening methods.     

Investigating the cause of excessive seepage in a dam foundation using seismic and electrical surveys—a case study of Asa Dam,West Africa

Bulletin of Engineering Geology and the Environment - A case study is reported in this paper, where a combination of seismic refraction and electrical resistivity surveys is used to investigate the...