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Zvinowanda C.M.,Tshwane University of Technology | Okonkwo J.O.,Tshwane University of Technology | Agyei N.M.,University of Limpopo | van Staden M.,National Metrology Institute of South Africa | And 2 more authors.
American Journal of Biochemistry and Biotechnology

Problem statement: Major adsorbent materials used in heavy metal ion removal from polluted aqueous streams are expensive and difficult to regenerate. In this study, the possibility of using Zea mays tassel, as an alternative low cost biosorbent material to remediate heavy metal pollution was investigated. Lead (II) was used because of its wide application in industrial products and well documented toxicity. Approach: Tassel was obtained from mature Zea mays cultivar R52 hybrid plants. The tassel was milled to a powder and was used to adsorb lead(II) ions from simulated solutions in batch experiments. The desorption of lead(II) was carried out using nitric acid and sodium citrate solutions. The adsorbent was characterized by FTIR, EDX and ESCA before and after application of lead(II) solutions. Results: For samples with concentrations of 100 mg L-1 Pb(II), 94-98% was adsorbed and 57-74 and 57-67% recoveries were achieved with 0.5-5 M nitric acid and 0.01-0.2 M sodium citrate as the stripping solutions, respectively. EDX spectrum of pure tassel indicated that group 1 and 2 metals were the major exchangeable ions present on its surface. ESCA analysis picked up small amounts of lead(II) in the form of Pb(OH)+ and Pb(NH)+ ions on the surface of tassel adsorbent exposed to Pb2+ ions and none on pure tassel sample. Functional groups such as -H, -NH2, -C = O and -COOH which are polar and are legends which are capable of binding heavy metals were identified by FTIR. Conclusion: The potential of Zea mays tassel to adsorb and recover heavy metals from aqueous solution was successfully demonstrated with Pb(II) sample solutions. The results obtained thus far demonstrated the possibility of using tassel powder in the removal as well as recovery of metals from aqueous solutions. © 2010 Science Publications. Source

Sekwati-Monang B.,University of Alberta | Sekwati-Monang B.,National Food Technology Research Center | Valcheva R.,University of Alberta | Ganzle M.G.,University of Alberta
International Journal of Food Microbiology

The choice of the cereal substrate determines sourdough microbiota, however, the substrate-associated ecological factors for this phenomenon have not been elucidated. This study investigated the competitiveness of Lactobacillus sanfranciscensis LTH 2590, a wheat sourdough isolate, and four isolates from sorghum sourdoughs (ting), Lactobacillus casei FUA3166, Lactobacillus harbinensis FUA3199, Lactobacillus parabuchneri FUA3169, and Lactobacillus coryniformis FUA3307, in sorghum sourdoughs, sorghum sourdoughs supplemented with maltose, or wheat sourdoughs. Fermentations were characterised by determination of cell counts, pH, and quantification of metabolites. Maltose was the main carbon source in wheat sourdoughs whereas glucose was the major carbon source in sorghum. L. coryniformis and L. parabuchneri produced 1,3- and 1,2-propanediol from glycerol and lactate, respectively, metabolites that were previously not observed in sourdough. To determine the competitiveness of strains, wheat and sorghum slurries were inoculated with equal cells counts of L. sanfranciscensis, L. parabuchneri, and L. casei fermented at 28. °C or 34. °C and propagated by back-slopping every 24. h. Lactobacilli in sourdough were quantified by plating and species-specific quantitative PCR (qPCR). Generally, sorghum and wheat sourdoughs inoculated with isolates from ting gave no appreciable differences in the metabolites produced during the fermentation process. L. sanfranciscensis grew in wheat but not in sorghum sourdoughs, or sorghum sourdoughs supplemented with 2% maltose, 1% tryptone, 0.1% l-cysteine and 2% sucrose. Furthermore, L.sanfranciscensis decreased progressively during propagation of sorghum sourdoughs but ting isolates were overgrown by L. sanfranciscensis after three propagations in wheat sourdoughs independent of the incubation temperature. The anti-microbial activity of four different types of sorghum extracts was tested against L. sanfranciscensis, L. parabuchneri, and L. casei to correlate the resistance to phenolic compounds to growth in wheat or sorghum sourdoughs. L. sanfranciscensis was inhibited by phenolic extracts from sorghum flours whereas ting isolates were resistant. In conclusion, microbiota of sorghum sourdough differ from wheat and rye because sorghum contains active concentrations of antimicrobial phenolic compounds, and offers glucose as major carbon source. © 2012 Elsevier B.V. Source

Holse M.,Copenhagen University | Petersen M.A.,Copenhagen University | Maruatona G.N.,University of Pretoria | Maruatona G.N.,National Food Technology Research Center | Hansen A.,Copenhagen University
Food Chemistry

Marama bean (Tylosema esculentum) is an underutilised legume indigenous to the Kalahari Desert region of southern Africa. The bean has high lipid content and hence is a potential source for production of edible oil. The headspace volatile composition of freshly pressed marama bean oil was explored and the oil was further studied during 7 months of storage under different light and temperature conditions. The oxidative stability of the oil was examined by measuring peroxide value, vitamin E content and FT-IR spectra. Additionally, the headspace volatile composition of the oil was investigated during storage by use of dynamic headspace GC-MS. The results showed that marama oil is highly stable and has good natural antioxidant properties; enzymatic lipid oxidation does not take place in marama oil. Light has a greater effect on the lipid oxidation than has temperature, and hence marama oil should preferably be stored in darkness and rather at 25°C than 35°C. Under these conditions, the marama oil has a shelf life of at least 7 months. © 2011 Elsevier Ltd. All rights reserved. Source

Tembwe I.,University of Botswana | Ngila J.C.,University of KwaZulu - Natal | Kgarebe B.,National Food Technology Research Center | Darkwa J.,University of Johannesburg | Iwuoha E.,University of the Western Cape
Electrochimica Acta

Nickel catecholate complexes, bis(diphenylphosphino)ethanenickelcatecholate [(dppe)NiO2C6H34-R1] R1 = CH3 (1), C(CH3)3 (2), H (3) and F (4)] were studied using CV and SWV techniques between -1.5 and +1.5 V at 50 mV s-1 in cathodic and anodic sweeps. Glassy carbon electrode was used with 0.1 M tetrabutylammonium tetrafluroborate (TBATFB) in CH2Cl2. Complexes 1-4 before addition of SO2, showed approximately reversible behaviour (ipa/ipc ≈ 1 and ΔE ≈ 77-88 mV); oxidation peaks observed between +313 and +524 mV, reduction peaks between +225 and +436 mV, depending on the substituent on the ligand. Detection limit 0.01 ppm, linear range 0.01-20 ppm, sensitivity 0.02 ppm/mV (with SWV) were obtained. The complexes 1 and 2 could be used as voltammetric sensors while complexes 3 and 4 would be suitable as amperometric sensors, for monitoring industrial SO2 emissions. © 2009 Elsevier Ltd. All rights reserved. Source

Mosele M.M.,Copenhagen University | Mosele M.M.,National Food Technology Research Center | Hansen A.S.,Copenhagen University | Hansen M.,Copenhagen University | And 2 more authors.
Food Chemistry

Marama bean (Tylosema esculentum) is a wild-growing legume adapted to semi-arid conditions in southern Africa. Both immature and mature seeds are used as food by locals and marama bean has potential as a crop plant. Physicochemical and histochemical methods were used to study the accumulation of nutrients and their localisation in immature and mature seeds. The immature seeds had a high content of moisture (67%) and protein (21%), and a low content of lipid (1.5%). At maturity, proteins formed spherical bodies that were embedded in a droplet lipid matrix. The mature seeds are exceptional as they have a high content of protein (32%) and lipid (40%) and no starch. Staining of polysaccharides indicated increases of pectin and cellulose during maturation, parallel with the general increase of cell wall thickness; however, lignin was absent. The content and distribution of protein, lipid and carbohydrates in immature and mature marama beans make this underutilised nutritive legume a prospective crop plant and interesting for food processing applications. © 2011 Elsevier Ltd. All rights reserved. Source

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