Evaluation of Bacterial Effects on Folic Acid Loss in Fortified,Nixtamalized Corn Masa Flour

Many Mexican women are deficient in folic acid. Fortification of the corn tortilla could be an effective way to help increase the folic acid levels among the Mexican population. Previous studies have shown significant folic acid losses in the masa dough as it is held before baking. This loss in folic acid could be owing to utilization by lactic acid bacteria naturally present in the masa. The objective of this study was to determine the effect of bacteria native to corn masa on the folic acid content in masa. Bacteria in dough samples from six mills in Guadalajara, Mexico, were isolated and identified. Bacterial isolates were inoculated into sterile fortified corn masa flour, which was converted to masa and held at 56°C for 0, 3, and 6 h, replicating the conditions of freshly milled masa as held before baking. All samples, including the control, showed losses of folic acid between 66 and 79% w/w in the first 3 h of incubation. Because folic acid degradation in the sterile control sample was not different than the inoculated sample results, the decline in folic acid was not owing to bacteria (mainly Streptococcus spp.) present in the masa flour but appeared to be a chemical degradation related to time and temperature.     

Acari (mite) assemblages under plantations of bluegum, Eucalyptus globulus, in southwestern Australia

Farm forestry, in particular the planting of exotic bluegums Eucalyptus globulus, is a strategy increasingly used in southwestern Australia to mitigate the damaging effects of land clearing and to improve agricultural productivity. At the same time, such agroforestry systems have the potential to at least partially impede the biodiversity decline associated with habitat destruction and agriculture. The soil/litter habitat, an important repository of biodiversity in terrestrial systems, is one of the habitats most affected by clearing and conventional agricultural practices. Within this habitat, free-living mites are one of the most diverse and abundant animal groups contributing significantly to key ecosystem functions. This study compares the soil and litter mite assemblages of 7-year-old E. globulus plantations with those of adjacent native forest and pasture sites. The assemblages associated with E. globulus were substantially more diverse than those of the pasture soils but well below that of the native forest. Particularly low densities of oribatid mites were observed in the plantation sites. We suggest that the young plantation age, the exotic nature of the plantation species, and the homogeneous, mono-specific litter all contributed to limit the potential for these plantations to enhance mite biodiversity.