Mineral contents of barley grains and its processed foods (kolo, porridge, bread and injera) consumed in Ethiopia

ABSTRACT. Barley (Hordeum vulgare L.) is one of the most widely cultivated stable food crops in the world. Barley grain samples were collected from four selected areas (Bahir Dar, Bure, Finote Selam and Debre Markos) of Ethiopia and four types of processed food (kolo, porridge, bread and injera) were prepared from it. The levels of essential and non-essential metals in barley grains and its processed food were determined by microwave plasma-atomic emission spectrometry after wet digestion with a mixture of HNO3 and HClO4 (5:1, v/v). The concentration (mg/kg dry weight) in the barley grains were in the ranges K (5482-6516), Mg (546-643), Ca (445-684), Mn (7.31-9.80), Fe (127-439), Cu (0.88-1.86), Zn (42.8-56.8), Pb (0.39-2.73), Cd (3.01-4.66). The concentrations of all the metals in the four types of processed barley foods showed variation among each other. The results indicate that Ethiopian barley grains and its processed foods are good source of essential metals.                     KEY WORDS: Barley, Hordeum vulgare L., Processed foods, Macro-minerals, Micro-minerals, Toxic metals   Bull. Chem. Soc. Ethiop. 2021, 35(3), 471-484. DOI: https://dx.doi.org/10.4314/bcse.v35i3.

Computational studies on heterogenization of homogeneous catalyst of iron(III), nickel(II) and copper(II) N,N′-disalicylidene-1,2-phenylenediamine complex

Density functional theory (DFT) calculations were carried out on iron(III), nickel(II) and copper(II) complexes of N,N′-ethylenebis(salicylimine) both at molecular level (isolated complexes) and encapsulated in a zeolite framework to investigate changes that occur in their geometrical and electronic parameters as well as in their reactivity and stability. The computational results showed that the zeolite encapsulated metal complexes have higher reactivity and less stability as compared to the isolated metal complexes.               KEY WORDS: Density functional theory, N,N′-ethylenebis(salicylimine), Computational studies, Heterogenization, Electronic parameters Bull. Chem. Soc. Ethiop. 2019, 33(1), 91-102DOI: https://dx.doi.org/10.4314/bcse.v33i1.

Assessment of the concentration of Cr, Mn and Fe in sediment using laser-induced breakdown spectroscopy

In the present study, laser-induced breakdown spectroscopy (LIBS) has been applied for the determination of levels of Cr, Mn and Fe in sediment samples and the results have been compared with that of flame-atomic absorption spectroscopy (F-AAS). Fourteen sediment samples were collected from Tinishu Akaki River (TAR), Addis Ababa, Ethiopia. Pellets of 24 mm in diameter and 3-5 mm in thickness were prepared using a manual hydraulic press under a pressure of 8000 psi by mixing finely ground sediment samples with boric acid. The concentrations of Cr, Mn and Fe were successfully determined by Q-switched Nd:YAG laser at 1064 nm. Quantification of these metals was conducted against certified reference materials of sediments and soils. The LIBS results for the elements varied from 0.060–0.707 mg/g for Cr, 0.895–3.64 mg/g for Mn and 26.9–71.8 mg/g for Fe. The F-AAS results varied from 0.061–1.37 mg/g for Cr, 1.24–4.46 mg/g for Mn and 49.0–83.3 mg/g for Fe. TAR was found to be heavily polluted with Cr. KEY WORDS: Laser-induced breakdown spectroscopy, Chromium, Manganese, Iron, Sediment, Tinishu Akaki River, Ethiopia Bull. Chem. Soc. Ethiop. 2013, 27(1), 1-13.DOI: http://dx.doi.org/10.4314/bcse.v27i1.

Assessment of essential and non-essential metals in Ethiopian traditional fermented alcoholic beverages

Evaluation of the levels of essential and non-essential metal concentrations in Ethiopian traditional fermented alcoholic beverages (Tella, Tej, Birz, Korefe, Keribo and Borde) was conducted using atomic absorption spectrophotometer (AAS) after HNO3/H2O2 digestion process. A total of 10 bulk samples were collected randomly from vending houses at five different sub-cities of Addis Ababa, the capital city of Ethiopia (Lideta-Kolfe, Bole-Kirkose, Yeka-Gullele, Arada-Addis Ketema and Akaki-Kaliti-Lafto) and from five nearby towns (Sebeta, Dukem, Sululta, Sendafa, and Burayu) of Oromia Regional State. The considered metals include: Ca, Mg, Fe, Zn, Cd, Cr, Cu, Ni, Pb, Co and Mn to ascertain their levels. With 88–96% recovery Ca, Mg, Fe, Zn, Cu, Cd, Pb and Mn were detected at varying concentrations in the beverages, while Co, Ni and Cr were below detection limits. All the beverages were rich in Ca, Mg and Zn. Among the trace metals found Zn was the first. The levels of the trace metals were generally low, and within statutory safe limits set by World Health Organization (WHO). Mineral concentrations were found to be significantly different among the beverages studied (p < 0.05). The levels of metals in the Ethiopian fermented beverages were found comparable with the reported ones

Total phenols and antioxidant activities of natural honeys and propolis collected from different geographical regions of Ethiopia

In this study, ten honey and five propolis samples from different geographical origins were tested. Both honey and propolis samples showed high content of total phenolic compounds (330-610 mg gallic acid equivalent (GAE)/100 g honey; 365-1022 mg GAE/g ethanol extract of propolis (EEP). The total flavonoids ranged from (15.1-42.6 mg catechin equivalent (CE)/100 g for honey; to 123-74 mg CE/g for EEP. These honeybee products of Ethiopia had high total radical scavenging properties with respect to 2,2-diphenyl-1-picryl-hydrazyl (DPPH); 18.1-59.8% and 48.6-87.8% for honey and EEP respectively. Furthermore, the hydroxymethylfurfural (HMF) of the honey samples was found to be low with a mean value of 4.8 mg/kg suggesting that the samples were of good quality. The antioxidant properties of the products showed a good correlation (r2 = 0.50-0.82) with their polyphenolic contents

Total contents of phenolics, flavonoids, tannins and antioxidant capacity of selected traditional Ethiopian alcoholic beverages

The aim of this study was to determine the total contents of phenolics, tannins and flavonoids and antioxidant capacity and their relationships in traditional Ethiopian alcoholic beverages. They have been determined utilizing Folin–Ciocalteu assay, aluminum chloride precipitating agent and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, respectively. The most widely consumed beverages and which have many varieties were selected for this study. These are gesho fermented and non-gesho beverages tella, tej, borde, keribo, birz, korefe and areke. The total phenolic content obtained in gallic acid equivalent (GAE) μg mL-1 was: areke (0.2–0.62), tella (10.1–19.1), tej (5.8–9.5), keribo (10.4–14.9), birz (10.5–12.2), korefe (9.2–10.7) and borde (8.4–10.6). The majority of phenolic compounds in the alcoholic beverages are non-tannic and non-flavonoid compounds. The antioxidant capacity obtained in ascorbic acid equivalent (AAE) μg mL-1 was: areke (-0.28–284), tella (31.6–201), tej (1.73–73.7), keribo (39.21–90.11), birz (41.95–63.08), korefe (58.25–96.45) and borde (180–217). The variation in the antioxidant activity among the beverages is due to the types and amount of ingredients used, disparity in the preparation process and the types of phenolic compounds found. The relationship between total phenolics and antioxidant activities was investigated using Pearson correlation at 95% confidence level. The results obtained indicate that the non-gesho fermented beverages such as keribo (-0.714), birz (-0.686) and borde (-0.212) have negative antioxidant correlation with the total phenolic, whereas, fermented beverages with gesho such as tella (0.539), tej (0.385) and korefe (0.557) have positive correlations. Areke has an overall positive correlation (0.609), but, the cereal areke which does not have medicinal plants has negative correlation. DOI: http://dx.doi.org/10.4314/bcse.v30i1.

Partial least squares−near infrared spectrometric determination of ethanol in distilled alcoholic beverages

In this study, using near infrared (NIR) spectrometry-partial least squares (PLS) calibration model was used for the determination of ethanol content in distilled alcoholic beverages. In NIR, 1660–1720 nm, the PLS modeling and analysis made use of 24 standards which contain 2–15% (w/w) ethanol with 0.1–1% (w/w) methanol. One-half was used for calibration and the other half for validation. Derivative, mean centering and subtracting minimum value were used as data treatment techniques for noise reduction and baseline correction. Mean centering has given the best partial least squares model with R2 = 0.999 and root mean square error of prediction (RMSEP) = 0.06 for ethanol and R2 = 0.929 and RMSEP = 0.08 for methanol, respectively. The percentage recovery obtained for ethanol and methanol ranges from 97–98% (w/w). The developed method produced good agreement with reference method, gas chromatography

Experimental and computational studies on zeolite-Y encapsulated iron(III) and nickel(II) complexes containing mixed-ligands of 2,2′-bipyridine and 1,10-phenanthroline

Mixed ligand complexes of 2,2′-bipyridine and 1,10-phenanthroline with iron(III) and nickel(II) have been encapsulated into a zeolite cage by the reaction of zeolite exchanged metal ion with flexible ligands. The synthesized catalyst has been characterized by X-ray powder diffraction, scanning electron microscopy, BET surface area and pore volume analysis, FT-IR spectroscopy, thermo-gravimetric analysis and elemental analysis. Density functional theory calculations have been carried out on both neat complexes as well as metal complexes encapsulated into NaY zeolite to investigate changes in structural parameters, energies of the HOMO and LUMO, and global hardness and softness of the two metal complexes upon encapsulation into zeolite. Experimental results confirm successful formation of a mixed ligand complex of Fe(III) and Ni(II) inside the zeolite cage. Density functional theory calculations predict a higher reactivity of the zeolite encapsulated metal complexes compared to respective metal complexes. The zeolite encapsulated Fe(III) and Ni(II) complexes are found to be catalytically active toward the oxidation of 2-phenyl phenol (OPP).Solomon Legese Hailu sincerely thanks the Leather Industry Development Institute (LIDI), Government of Ethiopia, Addis Ababa, for full nancial support for his PhD studies under Twinning Program between Leather Industry Development Institute (LIDI), Addis Ababa University (AAU) and CSIR-Central Leather Research Institute (CLRI). ID acknowledges CSIC, Spain for the research leave at AAU.Peer Reviewe

Synthesis, characterization and catalytic application of zeolite based heterogeneous catalyst of iron(III), nickel(II) and copper(II) salen complexes for oxidation of organic pollutants

In this study heterogeneous catalysts have been synthesized based on encapsulation of iron(III), nickel(II) and copper(II) complex of N,N′-Ethylenebis(salicylimine) or salen ligand into zeolite Y cavities by ship in a bottle method. The catalysts have been characterized by X-ray powder diffraction, BET surface area and pore volume analysis, FT-IR spectroscopy, thermo-gravimetric analysis, elemental analysis and electron paramagnetic resonance. The results show that ship in a bottle method is an efficient and simple approach for encapsulation of metal complexes into zeolite Y supercage. The prepared catalysts have been found to be very effective in the removal of azo dye from wastewater. The extent of its reusability for the catalytic oxidation of azo dye and the possible deactivation mechanism after ten successive reuse of the catalyst has also been studied.Solomon Legese Hailu sincerely thanks the Leather Industry Development Institute (LIDI), Government of Ethiopia, Addis Ababa, for full financial support for his Ph.D. studies under Twinning Program between Leather Industry Development Institute (LIDI), Addis Ababa University (AAU) and CSIR-Central Leather Research Institute (CLRI). ID acknowledges CSIC, Spain for the research leave at AAU.Peer Reviewe