The Effect of Natural Fermentation on Some Antinutritional Factors, Minerals, Proximate Composition and Sensory Characteristics in Sorghum Based Weaning Food
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Date
2009-06
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Addis Ababa University
Abstract
The effect of natural fermentation of two sorghum cultivars on antinutritional factors (tannin and
phytate), minerals (Ca, Fe, Zn and P), proximate analysis and sensory characteristics were investigated.
Flours from both cultivars were fermented at room temperature (20- 230 C) for 0, 12, 24, 36 and 48h at a
concentration of 1:3 dilutions (w/v). TTA and pH were determined immediately at the end of each
fermentation period and the samples were dried at 70o C in air oven drier for 36h. Fermentation caused
an increase in the protein, TTA, energy content and improved mineral bioavailability and decrease in
fat, carbohydrate, ash, crude fiber, viscosity, antinutritional factors, phytate: mineral molar ratios and pH
of sorghum flour. The bioavailability of zinc (phytate: zinc molar ratio <15) after 24-48h fermentation
of Gobiye cultivar was found to meet the critical limit. The bioavailability of calcium and iron was
below the critical limit in all the samples analyzed; phytate: calcium molar ratio >0.24 and phytate: Fe
molar ratio > 0.15. However calcium had no effect on the absorption of zinc ([Calcium x Phytate]:
[Zinc] <0.5 millimolar).When the samples were subjected to sensory evaluation, there was no significant
difference (p<0.05) in the appearance and aroma of the unfermented and gruel samples fermentation for
12h. The panelists however noted that appearance, aroma, texture, taste and overall acceptability of the
gruel prepared from sorghum flour that was subjected to 48h fermentation differ from others and least
acceptable. Taste and overall acceptability decreased significantly (p<0.05) along with period of
fermentation. Ethiopian weaning mothers should be encouraged to prepare 12 to 24h fermented sorghum
based weaning gruels that may blend with either legumes or milk powder by adding some amount of
sugar. Further research on cereal based fermented weaning foods needs to be conducted in Ethiopia.
Researchers should also take into consideration the incorporation of phytase enzymes into cereal plants
to enhance the nutritional value in addition to yield improvement by the application of biotechnology.
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Keywords
Proximate analysis and sensory characteristics were investigated