From cassava to gari: mapping of quality characteristics and end-user preferences in Cameroon and Nigeria

User’s preferences of cassava and cassava products along the value chain are supported by specific root quality characteristics that can be linked to root traits. Therefore, providing an evidence base of user preferred characteristics along the value chain can help in the functional choice of cassava varieties. In this respect, the present paper presents the results from focus group discussions and individual interviews on user preferred quality characteristics of raw cassava roots and the derived product, gari, – one of the major cassava products in Sub-Saharan Africa – in major production and consumption areas of Cameroon and Nigeria. Choice of cassava varieties for farming is mainly determined by the multiple end uses of the roots, their agricultural yield and the processing determinants of roots that support their major high-quality characteristics: size, density, low water content, maturity, colour and safety. Processing of cassava roots into gari goes through different technological variants leading to a gari whose high-quality characteristics are dryness, colour, shiny/attractive appearance, uniform granules and taste. Eba, the major consumption form of gari in Cameroon and Nigeria, is mainly characterised by its textural properties: smoothness, firmness, stickiness, elasticity and mouldability. Recommendations are made, suggesting that breeding will have to start evaluating cassava clones for brightness/shininess, as well as textural properties such as mouldability and elasticity of cassava food products, for the purpose of supporting decision-making by breeders and the development of high-throughput selection methods of cassava varieties. Women are identified as important beneficiaries of such initiatives giving their disadvantaged position and their prominent role in cassava processing and marketing of gari.     

Effect of chemical preservatives on shelf life of mushroom (Pleurotus ostreatus) cultivated on cassava peels

Short shelf life is a major impediment to the processing and distribution of mushroom. The effect of chemical preservatives on some quality attributes of mushroom during storage was investigated. Mushroom were soaked in four preservatives at two concentrations for 10 mins, packaged, stored at 4 °C for 30 days and analysed at intervals for their microbial population, colour, firmness and weight loss. Sodium benzoate (0.05%, 0.1%) lost its preservative effect on all the micro‐organisms enumerated after 3 days, and samples treated with 0.1% potassium sorbate had the lowest microbial load at the end of the storage period. Change in colour of the potassium sorbate (0.1%)‐treated sample was lower than and significantly different from the citric acid (2%, 4%)‐treated samples. The values of the firmness of the 4% citric acid preserved mushroom were significantly different (P ≤ 0.05) from other samples throughout the storage period. There was a significant negative correlation (r = ?0.807, P < 0.01) between the firmness and weight loss of the preserved mushroom. Potassium sorbate (0.1%) and citric acid (4%) extended the shelf life of mushroom for 24 days.     

Protein Isolates from Bambara Groundnut (Voandzeia Subterranean L.): Chemical Characterization and Functional Properties

The physicochemical, functional, and thermal properties of protein isolates obtained from two varieties of Bambara groundnut were evaluated. Proteins were isolated using alkaline extraction (isoelectric precipitation [IEP]) and micellisation techniques. IEP recorded a higher protein yield (56.3–58.2 g/100 g) than the micellised protein (MP) (14.2 – 15.6 g/100 g). A similar trend was observed for the protein content of the isolates. The isolates contained a high level of lysine, arginine, and glutamic acid compared to soy protein. Minimum solubility of the flours of the two varieties occured at pH 5. MP isolates exhibited higher solubility than the corresponding isoelectric (IEP) isolates over all pH values. The micellised protein recorded superior functional characteristics than the isoelectric isolates. The micellised isolates also showed a significantly higher (P < 0.05) foam capacity and stability, oil and water absorption properties than the isoelectric isolate. The MP of both varieties also recorded significantly higher emulsifying properties-+ than their isoelectric protein isolates. The micellised protein also had better gelation properties than the isoelectric isolate. Micellised and isoelectric isolates did not reveal major differences in the electrophoretic patterns; both isolates had three major bands at 35.0, 43.0, and 112.0 kDa. The bands in the isoelectric protein isolate however, were well defined compared with the micellised isolate. All Bambara isolates were not dissociated by 1,4-Dithiothreitol (DTT) suggesting that they do not contain subunits linked by a disulphide bond. This suggests that 7S vicilin may be the major storage protein in Bambara groundnut isolates. Differential scanning calorimetry studies (DSC) of the two varieties of bambara groundnut proteins indicated that the thermograms of the micellised isolates have a higher denaturation temperature Td (97.9–108.4°C) than their corresponding isoelectric isolates (89.5–90.6°C).     

Equilibrium, kinetic and sorber design studies on the adsorption of Aniline blue dye by sodium tetraborate-modified Kaolinite clay adsorbent

Raw Kaolinite clay obtained Ubulu-Ukwu, Delta State of Nigeria and its sodium tetraborate (NTB)-modified analogue was used to adsorb Aniline blue dye. Fourier transformed infrared spectra of NTB-modified Kaolinite suggests that modification was effective on the surface of the Kaolinite clay with the strong presence of inner -OH functional group. The modification of Kaolinite clay raised its adsorption capacity from 1666 to 2000 mg/kg. Modeling adsorption data obtained from both unmodified and NTB-modified Kaolinite clay reveals that the adsorption of Aniline blue dye on unmodified Kaolinite clay is on heterogeneous adsorption sites because it followed strongly the Freundlich isotherm equation model while adsorption data from NTB-modified Kaolinite clay followed strongly the Langmuir isotherm equation model which suggest that Aniline blue dye was adsorb homogeneous adsorption sites on the NTB-modified adsorbent surface. There was an observed increase in the amount of Aniline blue adsorbed as initial dye concentration was increased from 10 to 30 mg/L. It was observed that kinetic data obtained generally gave better robust fit to the second-order kinetic model (SOM). The initial sorption rate was found to increased with increasing initial dye concentration (from 10 to 20 mg/L) for data obtained from 909 to 1111 mg kg(-1)min(-1) for unmodified and 3325-5000 mg kg(-1) min(-1) for NTB-modified adsorbents. Thereafter there was a decrease in initial sorption rate with further increase in dye concentration. The linearity of the plots of the pseudo-second-order model with very high-correlation coefficients indicates that chemisorption is involved in the adsorption process. From the design of a single-batch adsorber it is predicted that the NTB-modified Kaolinite clay adsorbent will require 50% less of the adsorbent to treat certain volumes of wastewater containing 30 mg/L of Aniline blue dye when it is compared with the unmodified adsorbent. This will be cost effective in the use of NTB-modified adsorbent for the adsorption of Aniline blue dye from water and wastewater.     

Heat and mass transfer in an unsteady squeezed Casson fluid flow with novel thermophysical properties: Analytical and numerical solution

This study investigates the heat and mass transfer in an unsteady squeezing flow between parallel plates under the influence of novel variable diffusivity. In most of the literature, it is believed that the thermophysical properties of the fluid are unchanged. However, this present study bridges this gap by assuming that viscosity, conductivity, and diffusivity are all temperature-dependent. Physically, an appropriate analysis of thermophysical variables in such a system is required to achieve the best performance for effective heat and mass transfer processes. The equations controlled were first nondimensional and then simplified by a similarity transformation to ordinary nonlinear differential equations. The present study provides a fast convergent method on finite parallel plates, namely, the optimal homotopy analysis method (OHAM) and spectral collocation method (SCM) are used to analyze the fluid flow, heat, and mass transport. The graphical and table understanding is given via an error table and flow behavior of physical parameters. The result reveals that the SCM is more accurate than OHAM. However, the method employed in this paper offers excellent convergence solutions with good accuracy. The solution convergence is also discussed. In this type of problem, squeeze numbers play an important role and the rise in the squeezing parameter increases the fluid temperature.     

Doxorubicin-Induced Fetal Mesangial Cell Death Occurs Independently of TRPC6 Channel Upregulation but Involves Mitochondrial Generation of Reactive Oxygen Species

Doxorubicin (DOX), a category D pregnancy drug, is a chemotherapeutic agent that has been shown in animal studies to induce fetal toxicity, including renal abnormalities. Upregulation of the transient receptor potential cation (TRPC) 6 channel is involved in DOX-induced podocyte apoptosis. We have previously reported that TRPC6-mediated Ca²⁺ signaling promotes neonatal glomerular mesangial cell (GMC) death. However, it is unknown whether DOX alters mesangial TRPC expression or viability in the fetus. In this study, cell growth was tracked in control and DOX-treated primary GMCs derived from fetal pigs. Live-cell imaging demonstrated that exposure to DOX inhibited the proliferation of fetal pig GMCs and induced cell death. DOX did not alter the TRPC3 expression levels. By contrast, TRPC6 protein expression in the cells was markedly reduced by DOX. DOX treatment also attenuated the TRPC6-mediated intracellular Ca²⁺ elevation. DOX stimulated mitochondrial reactive oxygen species (mtROS) generation and mitophagy by the GMCs. The DOX-induced mtROS generation and apoptosis were reversed by the mitochondria-targeted antioxidant mitoquinone. These data suggest that DOX-induced fetal pig GMC apoptosis is independent of TRPC6 channel upregulation but requires mtROS production. The mtROS-dependent GMC death may contribute to DOX-induced fetal nephrotoxicity when administered prenatally.     

Isolation,fractionation and characterisation of proteins from Mucuna bean

The chemical composition and fractional distribution of protein isolates prepared from species of Mucuna bean were studied. Using six different extraction media, the yield of protein based on the Kjeldahl procedure varied from 8% to 34%, and the protein content varied from 75% to 95%. When the yields were high, the colour of the isolates generally tended to be dark and unsatisfactory. Hence, the use of chemical treatments and high pressure processing were explored.     

Effect of acetylation and succinylation on solubility profile, water absorption capacity, oil absorption capacity and emulsifying properties of mucuna bean (Mucuna pruriens) protein concentrate

Mucuna protein concentrate was acylated with succinic and acetic anhydride. The effects of acylation on solubility, water absorption capacity, oil absorption capacity and emulsifying properties were investigated. The pH-dependent solubility profile of unmodified mucuna protein concentrate (U-mpc) showed a decrease in solubility with decrease in pH and resolubilisation at pH values acidic to isoelectric pH (pH 4). Apart from pH 2, both acetylated mucuna protein concentrates (A-mpc) and succinylated mucuna protein concentrate (S-mpc) had improved solubility over the unmodified derivative. Acylation increased the water absorption capacity (WAC) at all levels of ionic strength (0.1-1.0 M). WAC of the protein samples increased with increase in ionic strength up to 0.2 M after which a decline occurred with increase in ionic strength from 0.4-1.0 M. When protein solutions were prepared in salts of various ions, increase in WAC followed the Hofmeister series in the order: NaSCN < NaClO4 < NaI < NaBr < NaCl < Na2SO. Acetylation improved the oil absorption capacity while the lipophilic tendency reduced the following succinylation. Emulsifying capacity increased with increase in concentration up to 2, 4 and 5% w/v for U-mpc, A-mpc and S-mpc, respectively, after which an increase in concentration reduced the emulsifying capacity. Both acetylation and succinylation significantly (P < 0.05) improved the emulsifying capacity at pH 4-10. Initial increase in ionic strength up to 0.4 M for U-mpc and 0.4 M for A-mpc and S-mpc increased the emulsion capacity progressively. Further increase in ionic strength reduced emulsion capacity (EC). Contrary to the effect of various salts on WAC, increase in EC generally follows the series Na2SO4 < NaCl < NaBr < NaI < NaClO4 < NaSCN. At all levels of ionic strength studied, S-mpc had a better emulsifying activity (EA) than both A-mpc and U-mpc. EA and emulsifying stability (ES) were pH-dependent. Maximum EA and ES were recorded at pH 10. ES of protein derivatives were higher than those of U-mpc in the range of pH 4-10 but lower at pH 2. Studies revealed that both A-mpc and S-mpc had better ES and EA than the unmodified derivative when protein solutions were prepared in salts of various anions.