Lactococci dominate the bacterial communities of fermented maize, sorghum and millet slurries in Zimbabwe.

Maize, sorghum and millet fermented porridges are important as complementary foods for young children in Africa. The objective of the present study was to gain some insights into the bacterial communities of fermented slurries prepared from maize, sorghum and millets originating from different locations in Zimbabwe, and prepared either at household or laboratory level. A deep sequencing approach targeting the hypervariable V4 region of the 16S rRNA gene was used and yielded about 100,000 sequences per sample. Lactococcus dominated all the fermented slurries, flanked by other lactic acid bacteria such as Weissella, Leuconostoc and Enterococcus. Enterobacteriaceae detected in the water samples persisted throughout all the fermented cereals. Other sub-dominant bacteria identified in the fermented slurries included Aeromonas, Pseudomonas and Acinetobacter. In addition, some Proteobacteria, Actinobacteria and Bacteroidetes associated with the raw materials and environment were also detected. Fermented slurries could not be differentiated based on their origin nor on the type of fermentation, but clear differences were observed between red sorghum fermented slurries and fermented slurries prepared from other cereal flours. A thorough understanding of the functional capacities of the microbiota in African fermented slurries is highly needed in order to steer the fermentation for the production of standard, safe and nutritious fermented products.

Iron and zinc bioaccessibility of fermented maize, sorghum and millets from five locations in Zimbabwe.

The present study is an evaluation of iron and zinc bioaccessibility of fermented maize, sorghum, pearl millet and finger millet from five different locations in Zimbabwe. Iron and zinc contents ranged between 3.22 and 49.7 and 1.25-4.39mg/100gdm, respectively. Fermentation caused a reduction of between 20 and 88% of phytic acid (PA) while a general increase in soluble phenolic compounds (PC) and a decrease of the bound (PC) was observed. Bioaccessibility of iron and zinc ranged between 2.77 and 26.1% and 0.45-12.8%, respectively. The contribution of the fermented cereals towards iron and zinc absolute requirements ranged between 25 and 411% and 0.5-23% with higher contribution of iron coming from cereals that were contaminated with extrinsic iron. Populations subsisting on cereals could be more at risk of zinc rather than iron deficiency.

Traditional fermentation of tef injera: Impact on in vitro iron and zinc dialysability.

Tef [Eragrostis tef (Zucc.) Trotter], an ancient cereal mainly produced in Ethiopia, is increasingly getting higher acceptance in the global market because it is gluten free and has high iron content. The aim of this study was to evaluate the in vitro dialysability of Fe and Zn in a backslop fermented gluten free flat bread known as injera. The traditional fermentation caused up to 49-66% reduction of phytic acid (PA). Molar ratios of PA:Fe and PA:Zn decreased from 14 to 1 and from 63 to 19, respectively, after 120h of fermentation. The total soluble fractions of Fe and Zn ranged between 11 and 38% and between 11 and 29%, respectively, after 120h of fermentation. The dialyzable Fe content of the white varieties ranged between 3 and 9% after 120h fermentation while no effect was observed for the brown varieties. The dialyzable Zn ranged between 2 and 11%, with only a clear effect of fermentation in one white variety. Consumption of tef could be a good source of Fe and Zn, but may not provide the absolute recommended daily Fe and Zn intakes.

Effect of Fermentation and Cooking on Soluble and Bound Phenolic Profiles of Finger Millet Sour Porridge.

The aim of this study was to evaluate the soluble and bound phenolic content of finger millet and the impact of process induced changes on phenolic profiles of their sour porridge. Finger millet porridge and intermediate products were collected from four groups of households in the Hwedza communal area, Zimbabwe, after which soluble and bound phenolic compounds (PC) including condensed tannins (CT) were quantified. Bound PC and CT contributed 95% of the total PC and CT. The CT were only detected in the red varieties. Major individual PC identified were catechin occurring in the soluble fraction only, while ferulic, sinapic, and salicylic acid were mainly present in the bound fraction. Fermentation and cooking caused a more than 2-fold increase in soluble PC, CT, and individual PC. Improved traditional processing techniques optimized for improved bioavailability and health benefits of phenolics are highly relevant for the low income populations.