The role of pH in heavy metal detoxification by biosorption from aqueous solutions containing chelating agents

The high level of toxic metal pollution in the environment is a result of increased human activities. The hydrogen ion concentration of solutions has been known to affect reactions in solutions. The role of pH in As(V), Pb(II) and Hg(II) ions detoxification by bio-sorption from aqueous solutions using coconut fiber and sawdust waste biomass, containing chelating agents was studied. pH characteristically influenced adsorption. Maximum adsorption occurred at pH 2 and 12 whereas minimum adsorption occurred at pH 6-8. Modification of the adsorbent by carboxymethylation and thiolation decreased the absorption capacity. As(V) metal ion was adsorbed more than Hg(II), then followed by Pb(II) ion. A model was proposed for the action of pH on the adsorption pattern of the metal ions on the adsorbents used. Desorption studies was investigated using NaOH and H2PO4. Therefore, these results can serveas parameters for design of treatment plants for heavy metal detoxification using agricultural byproducts, such as sawdust and coconut fiber

Effect of Fermentation Time and Leavening Agent on the Quality of Laboratory Produced and Market Samples of Masa (A Local Cereal Based Puff Batter)

Evaluation of production techniques, quality of market samples and effects of fermentation times (6 and 8hrs), leavening agents (yeasts and baking powder) and shelf life (fresh and 24h) on the quality of masa were carried out through interviews, processing operations, laboratory analyses and sensory studies. Statistical analyses were carried out using the SPSS Statistical Package. Variations in processing techniques among masa producers were method of preparing the rice, soaking time for the rice (4 – 6h), the time paste was allowed to stay before baker’s yeast was added (3 – 4h), frying time (4 -5 minutes) and ratios of cooked rice to soaked rice (1: 2 and 1: 4). Uniform practices among masa producers were washing, wet-milling, fermentation time (overnight), addition of yeast, salts and sugars and dilution of fairly thick batter with trona (baking powder) before frying. Functional properties of rice were foam capacity (23.7%), foam stability (88.5%), water absorption capacity (0.02%), gelation capacity (20%), gelatinization temperature (82oC) and gelation time (20 minutes) Significant differences were observed between the masa samples for ash, moisture, protein, lipid and total bacterial counts (p ≤ 0.05). Their ranges for both laboratory-processed and market samples, respectively were; moisture (10.2 – 11.7% and 12.0 – 13.7%); protein (7.1 – 7.6% and 7.6 – 8.2%); lipid (1.9 – 2.4% and 2.4 – 2.6%); ash (0.4 – 0.7% and 0.6 – 0.8%) and total bacterial counts (1.2 x 101 – 1.6 x101 cfu/g). For the first day of their production, significant differences (p ≤ 0.05) were observed for all the sensory factors for both laboratory-processed and market samples of masa. Based on sensory scores, all the laboratory-produced masa samples were organoleptically acceptable without much significant difference (p ≥ 0.05) except for masa fermented for 8h without leavening agent. The mean sensory scores of all fresh market samples of masa were less than 4.0 on a 7-point Hedonic scale. Significant differences were observed between the market and laboratory processed samples of masa after the first day of production for all the sensory factors (P ≤ 0.05) and 50% of market and laboratory produced masa samples were not sensorially acceptable. Unlike freshly produced (for both market and laboratory) masa samples, it was found out that after the first day (24h) of production, the trend was not the same. This is because unlike market samples of masa, laboratory prepared masa samples without leavening agents, were as unacceptable as masa samples with leavening agents.Key words: Masa, quality, Fermentation, Leavening, processin

Quality evaluation of dakuwa and effect of ratios of tigernut to groundnut in dakuwa production

Evaluation of market and laboratory-processed samples of Dakuwa and effects of ratios of tiger nut to groundnut mix (4:1, 3:1, 2:1 and 1:1) on their organoleptic acceptability were carried out through field, laboratory and sensory studies. Results showed tiger nut and groundnuts were major cereals used for Dakuwa production, though sorghum and maize in place of tiger nuts were used by few producers. Ratios of tiger nut to groundnut varied (3:1, 2:1 and 4:1) but ratio 2:1 was most popular. Significant differences were observed for moisture, lipid, protein, ash and pH of both laboratory and market samples (P ≤ 0.05). High microbial load of market samples suggested unsanitary production and handling. Laboratory and market samples were respectively for moisture: 11.67 to 16.50 and 23.33 to 39.20; for lipid: 24.86 to 30.04 and 24.97 to 32.56; for protein: 7.80 to 9.00 and 7.90 to 10.27; ash: 1.63 to 2.50 to 3.48; and pH: 5.79 to 5.95 and 6.15 to 6.59 while higher microbial loads were observed for market samples. Except MD-DD, all samples of Dakuwa were acceptable as their sensory scores were less than 4.0 on a 7-point scale. Significant differences were observed on general acceptability for both the market and laboratory samples (P ≤ 0.05). MD-BB was most liked for market samples whereas LD-BB was most liked for laboratory sample. The least liked ratio of tiger nut to groundnut in Dakuwa formulation was 4:1. In conclusion, no significant differences (P ≥ 0.05) were observed between Dakuwa samples made from ratios 3:1, 2:1 and 1:1 but numerically ratio 2:1 was the most acceptable.Keywords: Dakuwa, Groundnut, Tigernut, quality

Risk and health implications of polluted soils for crop production

Studies of polluted soils have shown heavy metals contamination of the soils as well the uptake of these toxic elements by plants. Consequently, there are reasons for concern over elevated concentration levels of heavy metal/toxic elements in polluted soils. This can ultimately result in high human and animal exposure to these toxic elements through food-chain transfer, ingestion of wind blown dust or direct ingestion of soils. The toxic effects caused by excess concentrations of heavy metals in living organisms include competition for sites with essential metabolites, replacement of essential ions, reactions with –SH groups, damage to cell membranes and reactions with the phosphate groups