Salts soaking treatment for improving the textural and functional properties of trifoliate yam (Dioscorea dumetorum) hardened tubers.

Processing of Dioscorea dumetorum hardened tubers into flour could be a means of adding a longer-term value to this tropical plant with a high nutritional potential, but which presents a postharvest hardening problem characterized by a hard-to-cook defect. In an attempt to investigate the changes leading to salts soaking treatment of hardened tubers, the central composite rotatable design for K= 2 was used to study the combined effect of NaCl concentration (0% to 6%) and pH (4 to 10) on tubers cooked hardness, and 6 kanwa alkaline salt concentrations (1:3 (w/v); 0%, 0.2%, 0.5%, 0.8%, 1%, and 1.5%; pH 11.3 +/- 0.2) were used to study the effect of kanwa treatment on tuber cooked hardness and functional properties of resulting flours. The results showed that salts soaking treatment significantly decreased (P

Viscosity, energy density and osmolality of gruels for infants prepared from locally produced commercial flours in some developing countries.

Forty market samples of locally produced (33) and imported (7) cereal-based flours used for complementary feeding in some African countries and Vietnam were studied in order to characterise their macronutrient content and, when prepared as gruels, their viscosity, energy density, and osmolality. The results show that less than half were fairly balanced with respect to their protein and lipid content. When prepared as gruels following the manufacturers' instructions, out of the 21 locally produced flours with complete instructions, ten had energy densities too low to provide sufficient energy to complement breastmilk for 9-11-month-old infants even at three meals a day (< 77 kcal or 322 kJ/100 g), nine were satisfactory if fed more than twice a day, and two if fed twice a day (> 116 kcal or 485 kJ/100 g). Two of the 11 with acceptable energy density had osmolality values higher than those reported in literature for complementary feeding (< 660 mOsm/kg H2O). In addition, when prepared as gruels with viscosities within the range of viscosity (1 to 3 Pa.s) usually observed in African countries, 14 of the 32 (44%) locally produced flours had insufficient energy densities to meet the energy requirements of infants even at three meals a day. These results call for greater concern and effort towards improving the nutritive value and energy density of cereal-based complementary foods produced in developing countries.

Review of heavy metals in the African aquatic environment.

Data were compiled from selected heavy metal studies in both freshwater and marine ecosystems from the major African subregions, Northern, West and Central, Eastern, and Southern Africa. The concentrations of heavy metals were compared between different environmental compartments (water, sediments, fauna, and flora), between the different African subregions and with data from other areas in the world. Despite the scarcity of the existing information on Africa, some conclusions could be drawn: Metal concentrations in organisms were generally below WHO limits except for some localized sites, mostly with increased lead levels. There were no significant differences between inland water and coastal animals, but shellfish had higher concentrations of most metals than finfish. For aquatic plants the heavy metal levels were higher in inland waters. Compared to more industrialized regions and with the exception of some hot-spot sites, the concentrations of heavy metals in African aquatic systems were low and close to natural background levels. Nevertheless, in view of the expected increase in urbanization and socio-economic activities in Africa, sources and quantities of heavy metal discharges to aquatic environments have to be identified. Also, pollution control measures should be formulated in each country.