Improved iron and zinc availability in sorghum by phytate reduction through genetic modification, fermentation and phytase addition
type: CreativeWork
description: Iron and zinc deficiencies are highly prevalent in the developing world. In worst cases, the cause of iron and zinc deficiency may be actual insufficient dietary intake, but inhibitors of absorption, mostly found in plant foods, contribute substantially to these deficiencies. Sorghum is an important staple crop in Africa, often in populations with severe iron and zinc deficiencies. Sorghum is commonly consumed as whole grain. While the bran of sorghum contains the most iron, it also contains phytate and sometimes also tannins, depending on the cultivar, which further reduce the already low bioavailability of non-haem iron and zinc. The aim of this research was to evaluate the effect of reducing sorghum and maize phytate content through genetic modification (GM) on in vitro iron and zinc availability in porridges and raw cereal lager brewer’s wort. The effect of phytate reduction through GM on iron and zinc availability was also compared with the effect of phytate reduction through natural lactic acid fermentation and the addition of exogenous phytase. Iron and zinc availabilities were assessed using a dialysability assay (bioaccessibility), Caco-2 cell (uptake) study and an in vivo suckling rat pup model (absorption). A mineral solubility assay was used to analyse the soluble minerals in the raw cereal wort. GM low phytate (approx. 30-40% reduction) non-tannin and tannin sorghums and their respective null controls (NC) were processed into thick unfermented and fermented porridges. The inhibitory effect of the tannins on mineral availability seemed to prevent any increase in in vitro iron and zinc bioaccessibilities regardless of the level of phytate reduction. However, the additive effect of GM in combination with fermentation in reducing the porridge phytate content, caused a substantial increase in in vitro iron bioaccessibility in the non-tannin line. The percentage bioaccessible iron in the GM fermented porridge was approximately 30%, compared to the GM unfermen…
abstract: Iron and zinc deficiencies are highly prevalent in the developing world. In worst cases, the cause of iron and zinc deficiency may be actual insufficient dietary intake, but inhibitors of absorption, mostly found in plant foods, contribute substantially to these deficiencies. Sorghum is an important staple crop in Africa, often in populations with severe iron and zinc deficiencies. Sorghum is commonly consumed as whole grain. While the bran of sorghum contains the most iron, it also contains phytate and sometimes also tannins, depending on the cultivar, which further reduce the already low bioavailability of non-haem iron and zinc. The aim of this research was to evaluate the effect of reducing sorghum and maize phytate content through genetic modification (GM) on in vitro iron and zinc availability in porridges and raw cereal lager brewer’s wort. The effect of phytate reduction through GM on iron and zinc availability was also compared with the effect of phytate reduction through natural lactic acid fermentation and the addition of exogenous phytase. Iron and zinc availabilities were assessed using a dialysability assay (bioaccessibility), Caco-2 cell (uptake) study and an in vivo suckling rat pup model (absorption). A mineral solubility assay was used to analyse the soluble minerals in the raw cereal wort. GM low phytate (approx. 30-40% reduction) non-tannin and tannin sorghums and their respective null controls (NC) were processed into thick unfermented and fermented porridges. The inhibitory effect of the tannins on mineral availability seemed to prevent any increase in in vitro iron and zinc bioaccessibilities regardless of the level of phytate reduction. However, the additive effect of GM in combination with fermentation in reducing the porridge phytate content, caused a substantial increase in in vitro iron bioaccessibility in the non-tannin line. The percentage bioaccessible iron in the GM fermented porridge was approximately 30%, compared to the GM unfermen…
language: en
keywords: UCTD, Sorghum, Raw cereal lager brewer’s wort, Iron and zink deficiencies
date published: 2012-05-15
date modified: 2026-07-24T03:52:34Z
provider: University of Pretoria
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Pretoria

PropertyValue
property ID: Handle
value: http://hdl.handle.net/2263/30814