Chemical, structural, and techno-functional characterization of yam (Dioscorea) flour from South West Ethiopia.

Yam (Dioscorea spp.) is a versatile tuber crop that holds nutritional, cultural, and economic values. Yam is a major source of carbohydrates for tropical Countries and provides various nutrients and health benefits. This study aims to characterize the chemical, structural, and thermal properties of yam flour using various analytical techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermal analysis. Additionally, the pasting and rheological properties of yam flour were evaluated, as they are crucial for product development and enhancing the value of this unconventional vegetable. D. cayenensis complex had the highest total starch (64.63 ± 1.61 %) and soluble sugar (4.95 ± 0.46 %) content, which was significantly higher than other yam species. The amylose content of yam flours showed significant (p < 0.05) differences among the yam species. D. cayenensis flour exhibited significantly the highest peak (2923.66 cP) and steak back viscosity (2097.66 cP) among the yam species associated with their greater amylose content. There were notable variations in pasting and gelatinization parameters among the species. The peak temperatures of D. bulbifera and D. cayenensis complex were significantly (p < 0.05) higher than D. cayenensis and D. rotundata flours. The rheological measurements of yam flours demonstrated solid-like behavior with varying intensities. Furthermore, the morphology of tuber yam flour particles was oval to ellipsoidal shaped, with some appearing ovoid, and the smaller granules appearing spherical. The X-ray diffraction showed that all yam flours exhibit a B-type pattern. This study provide a better understanding of this unconventional vegetable's potential applications in the food industry and contribute to its value addition.

Antibacterial and antioxidant potential analysis of Verbascum sinaiticum leaf extract and its synthesized silver nanoparticles.

The potential applications of plant extract and nanoparticles in antibacterial and antioxidant studies have garnered significant interest in recent times. Despite being utilized in Ethiopian traditional medicine, Verbascum sinaiticum (qetetina) constituents and its usage in nanoparticle synthesis remain relatively unexplored. This study explores the potential of the plant extract and its nanoparticles for antibacterial and antioxidant applications, with a focus on the leaf extracts and its silver nanoparticles. The leaf extract was analyzed using LC-MS and GC-MS and found to contain over 70 compounds, including glycosides, phenolic compounds, flavonoids, and fatty acids. The synthesized nanoparticles had a maximum absorbance of 408 nm, with a size range of 2-40 nm and showed a spherical shape. Using the agar well diffusion method, the extract and nanoparticles were evaluated against Gram-positive (Staphylococcus aureus ATCC 2592, Streptococcus agalactia ATCC12386) and Gram-negative bacteria (Acinetobacter baumannii ATCC19606, Pseudomonas aeruginosa ATCC27853) bacterial strains. In terms of antibacterial effects, both the silver nanoparticles and leaf extract displayed a greater impact on gram-positive bacterial strains over gram-negative bacterial strains. Additionally, the tests for lowest inhibitory and bactericidal concentration indicated similar outcomes. Notably, the silver nanoparticles exhibited greater antibacterial activity compared to the leaf extract alone. The DPPH (2, 2-diphenylpicrylhydrazyl) assay was conducted to investigate antioxidant activity. The results showed that the plant extract had an IC50 value of 143 µg/ml, while the synthesized nanoparticle had an IC50 value of 216 µg/ml, indicating that the plant extract had greater antioxidant activity than the synthesized silver nanoparticles.

Method optimization for the determinations of selected phytochemicals and antioxidant activities of wild Ethiopian Syzygium guineense fruit and seed under different drying conditions.

This study aimed to optimize the ultrasound-assisted extraction (UAE) parameters using response surface methodology (RSM) for the determination of ascorbic acid (AA), antioxidant activities/the half maximal effective concentration (EC50), total phenolic contents (TPC), and total flavonoid content (TFC) of Ethiopian wild Syzygium guineense fruit and seed processed under different drying conditions. The optimizations of the UAE methods for the determination of AA, antioxidant activities (EC50 values), TPC, and TFC were evaluated using response surface methodology (RSM). The extraction time of 15 min, the temperature of 35 °C, extraction solvent composition (methanol:water) of 75 to 25%, and solid-to-solvent ratios of 1:15 w/v were the optimum independent parameters. The experimental and the predicted data of TPC, EC50, and AA were in good agreement with the overall error below 0.01%. It also indicated a hypothesized distribution of predicted data fitted with experimental data. The average TPC, EC50, and AA content in S. guineense fruits and the seed varied from 581.25 ± 37.13 to 1917.40 ± 26.15 mg GAE/100 g, 4.02 ± 0.42 to 155.73 ± 5.11 mg/100 g, and 1.96 ± 0.02 to 0.94 ± 0.00 mg/mL, respectively. This study indicated that this underutilized wild fruit and its seeds can be an alternative source of AA and antioxidant compounds.

Anchote (Coccinia abyssinica [Lam.] Cogn.) powder, an underutilized indigenous crop, as a substitute to commercial pectin in the production of strawberry jam.

The study investigated the potential of anchote (Coccinia abyssinica [Lam.] Cogn.) tuber powder as a substitute to commercial pectin. Mixture D-optimal design was used to generate 14 experimental runs using ranges: strawberry fruit (45-55%), sugar (43-53%), and anchote powder (0.75-1.75%). The effect of anchote powder on physicochemical and textural qualities of the jams was evaluated. The parameters measured include: moisture content (30.7-32.8%), total soluble solid (50.7-65.4 ºBrix), water activity (0.73-0.80), pH (2.93-3.13), titratable acidity (0.58-0.72%), gel strength (326.39-440.37 g mm), hardness (26.36-35.09 g), cohesiveness (0.89-0.94), energy of penetration (418.72-489.51 g s), adhesiveness (-25.38 to -103.79 g s) and stickiness (-13.78 to -29.22 g). The jam formulation J13 (50% strawberry, 48.2% sugar, 1.33% anchote) was best performing. Numerical optimization showed the best combination of parameters at 52.4% strawberry, 46.0% sugar, 1.07% anchote. The jam formulated with anchote powder was comparable with the jam made using pectin.

Starch composition and functional properties of raw and pretreated anchote (Coccinia abyssinica (Lam.) Cogn.) tuber flours dried at different temperatures.

Anchote (Coccinia abyssinica (Lam.) Cogn.) is an indigenous tuber crop produced in southwest part of Ethiopia. As an indigenous and underutilized tuber, limited scientific information is available about the characteristics of dried anchote powder. In this study, attempts were made to investigate the starch composition and functional properties of flours produced from the raw and pretreated tuber dried at different temperatures (60, 80, and 100°C). The results showed that both pretreatment and drying temperature significantly (p < .05) affected the amylose/amylopectin ratio, pH, total soluble solids (TSS), water absorption capacity (WAC), oil absorption capacity (OAC), water absorption index (WAI), water solubility index (WSI), swelling power (SP), total polyphenols content (TPC), and total flavonoid content (TFC). The treatment combinations result in varied ranges of pH (5.70-6.47), TSS (5.37-10.8 °Brix), WAC (2.42-4.21 g/g), OAC (0.94-1.44 g/g), WAI (3.40-5.42 g/g), WSI (11.40%-20.37%), SP (4.56-7.20 g/g), foaming capacity (FC) (3.31%-33.33%), foam stability (FS) (1.89%-20.00%), amylose content (AC) (14.18%-36.11% ), TPC (0.22-0.80 mg GAE/g), and TFC content (0.12-0.44 mg CE/g). The blanched and boiled anchote flours dried at relatively lower drying temperature exhibited better WAC, SP, and WAI than the raw. Considering the determined parameters, the flour from the tuber can be used as an ingredient in different food formulations.

Effect of predrying treatment and drying temperature on proximate composition, mineral contents, and thermophysical properties of anchote (Coccinia abyssinica (Lam.) Cogn.) flour.

Anchote (Coccinia abyssinica (Lam.) Cogn.) is an indigenous underutilized but valuable root crop solely consumed in Ethiopia. It is commonly used as occasional food during holidays and as therapeutic food to treat fractured bone or develop strong bone. So far, different studies conducted related to its variety development, nutrition, and anti-nutrition contents. In this study, attempts were made to investigate the effect of predrying treatments and drying temperature on nutritional composition and thermophysical properties of its flour. A general full factorial experiment with two factors each at three levels used to run the experiment. The proximate compositions, thermophysical properties, and mineral contents were determined using AOAC standard methods; well-developed model equations; and atomic absorption spectrophotometry, respectively. The ranges of nutrients in mg/100 g DB were as follows: moisture content (MC) 7.37-10.10; protein 3.26-4.80; total fiber (TF) 7.24- 10.76; ether extract (EE) 0.49-0.70, ash 2.96-4.74, total carbohydrate (TC) 80.01-83.66; calcium (Ca) 357.07-482.89; magnesium (Mg) 138.87-222.38; iron (Fe) 10.87-16.00; zinc(Zn) 2.07-2.80; and copper(Cu) 1.90-2.25. The bulk density, specific heat capacity, thermal conductivity, and thermal diffusivity of the flours ranged in 0.72-0.82 (g/cm3), 1.710-1.780 KJ/kg°C, 0.263-0.273 W/m2°C, and 1.88 x 10-4- 2.12 × 10-4 m2/s, respectively. The predrying treatment and drying temperature significantly affected (p < .05) MC, protein, TF, EE, ash, TC, Ca, Fe, and Zn contents. The thermophysical properties were also affected by the same factors. The flour made from raw anchote dried at 100°C was better in preserving the nutrients and improving its cooking property.