Ermias Abelneh Tesema

The environmental and health burden of synthetic textile dyes has renewed interest in natural colorants from renewable, non-food resources. This study evaluated Agave sisalana (AS) leaf waste an abundant agro-industrial residue as a cotton dye alongside three local candidates ( Rumex nervosus flower, Syzygium guineense and Carissa edulis fruit peels). Dyes were recovered by methanolic maceration (70% methanol, 1:10 w/v, 72 h) and screened for total flavonoid content (TFC), total phenol content (TPC) and colour strength (K/S). AS was selected because it combined the highest TFC (7.52 ± 0.26 mg QUE g⁻¹) with the highest K/S on cotton. Qualitative phytochemical screening identified flavonoids, tannins and anthocyanins as the principal colorants, while alkaloids, glycosides, anthraquinones and steroids were not detected; UV–Vis and FTIR profiles were consistent with the results of the qualitative phytochemical screening. The dye was a shelf-stable powder (moisture 4.89%, water activity 0.56) highly soluble in 50% methanol and hot water. Dyeing of mordanted cotton was optimized by a three-level full-factorial design (40–100 °C, 30–90 min, 25–75 mg mL⁻¹) using quadratic response surfaces; FeSO₄ outperformed KAl(SO₄)₂. Optimum conditions (78 °C, 64 min, 61.6 mg mL⁻¹) gave 62.4% dye uptake and K/S 7.28 (experimental), compared with model predictions of 56.0% and 7.39; K/S agreed with its prediction within 1.5%, whereas the measured dye uptake exceeded its prediction by about 11%. Washing fastness was good to ten cycles. Agave sisalana leaf waste is therefore a viable, eco-friendly cotton dye, though the high dye load reflects the crude extract.

This study examined the influence of malting conditions on the quality of finger millet (Eleusine coracana, Mecha variety) malt and its brewing potential. A 3 × 3 × 3 factorial design was applied, varying germination temperature (20–30 °C), germination time (2–4 days), and curing temperature (70–90 °C). The malts were characterized by germination energy, enzyme activity, protein and tannin content, as well as brewing performance indicators including diastatic power and hot water extract. Through the interaction of 30 °C germination temperature and 4-day duration meeting international malting standards. Higher germination temperatures and longer durations improved enzyme activity and modification, though accompanied by greater weight loss (20.3–24.5%) and reduced moisture (2.1–4.5%). Wort analysis yielded hot water extract values of 77.7–90.7% (dry basis), with upper values surpassing EBC standards, suggesting possible over-modification under certain treatments. These findings demonstrate finger millet’s suitability as an alternative brewing raw material and support its potential for commercial millet-based beer production in Ethiopia and beyond.

During peak seasons, postharvest loss of mangoes remains a significant challenge for smallholder farmers in Ethiopia, driven by high production volumes, limited market access, and a lack of preservation methods. The objective of this research was to develop and enhance the performance of a solar cabinet dryer for mango slices through Computational Fluid Dynamics (CFD) simulations. A solar cabinet dryer incorporating a rectangular baffle solar collector was developed, built, and experimentally validated. The CFD simulation results showed a temperature difference of 4.35% and a relative humidity deviation of 7.8%, indicating good agreement with the experimental data. The model optimized the baffle design and inlet air velocity to maximize outlet temperature and minimize pressure drop. The optimal design was identified using Response Surface Methodology (RSM) in conjunction with ANSYS software. The best-performing configuration featured four baffles with 25% cut openings and an inlet air velocity of 1 m/s. The porous domain of mango slices was incorporated into the model to predict moisture transport with experimental effective diffusivity of (5.224 × 10⁻⁷ m²/s). Results showed that the designed dryer achieved uniform temperature and moisture distribution, with higher drying rates observed near the lower trays. .The moisture content in mango slices was reduced from 45942.17 mol/m³ to 2,677 mol/m³ within two hours of drying. The CFD model showed strong predictive accuracy with only minor discrepancies observed in the simulation of temperature, relative humidity, and moisture movement. The developed dryer provides a sustainable and cost-effective solution to reduce postharvest mango losses with an efficient design that enhances food security and farmer livelihoods. Keywords: CFD modeling, heat and mass transfer, mango slices, postharvest loss, solar dryer

Methylene blue dye contamination poses serious environmental and health risks, necessitating efficient removal methods. Conventional Zinc Oxide (ZnO) nanoparticles synthesized chemically face issues like toxicity, instability, and agglomeration, reducing their effectiveness. This study explores the green synthesis, characterization, and application of teff straw-assisted ZnO nanoparticles, using neem leaf extract as a capping agent, for MBD removal from textile wastewater. Characterization via X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) confirmed functionalization, with an average crystalline size of 27.196 nm. Adsorption experiments analyzed the impact of pH, adsorbent dose, contact time, and initial dye concentration, while Response Surface Methodology (RSM) with a Central Composite Design (CCD) optimized conditions, achieving 99.77% removal efficiency at pH 6.9, 68.5 mg/L dye concentration, 0.265 g adsorbent dose, and 77.87 min contact time, fitting the Freundlich isotherm model (R² = 0.99). Real textile wastewater treatment showed 92.5% removal efficiency, proving teff straw-assisted ZnO nanoparticles as a sustainable, eco-friendly alternative for wastewater treatment.

In the present work, effect of potato variety, pretreatments (5% brine, 0.5% potassium Meta bi-sulphite (KMS) and blanching at 70°C for 3 minutes) and airflow mode on drying kinetics and effective moisture diffusivity of potato slices was investigated in a cabinet solar dryer with a heat storage system. The experiment was conducted in a full factorial design arranged in a completely randomized block design and the drying kinetics was modelled using commonly used well known equations. From the result; potato variety, air flow mode (natural vs. forced convection) and pre-treatments significantly affected the drying kinetics of the slice in which the brine-treated sample took a shorter drying time followed by blanched and KMS-treated slices. However, the blanched sample exhibited a higher effective moisture diffusivity and drying rate than untreated and KMS-treated samples. Brine treated sample has the lowest effective moisture diffusivity and drying rate. Tolcha variety dried faster than the Jalo variety followed by the Gera variety. The goodness of fit to the tested models were also evaluated based on R2, chi-square and RMSE values in which a model with the highest R2 ,lowest X2 and RMSE values were selected as a best fitted model. As result, Boltzmann model with R2 (0.9985) was the best fitted model in Blanched sample, whereas Midihilli and Kucuk model was best fitted with brine-treated and control samples, with R2 values ranging from 0.9995 in the control sample to 0.9999 in the brine-treated sample.