African Journal of
Food Science

  • Abbreviation: Afr. J. Food Sci.
  • Language: English
  • ISSN: 1996-0794
  • DOI: 10.5897/AJFS
  • Start Year: 2007
  • Published Articles: 937

Full Length Research Paper

Phytate degradation in composite wheat/cassava/sorghum bread: Effects of preincubation of Pichia kudriavzevii TY13 and presence of yeast extract

Vilanculos Serafina Lídia
  • Vilanculos Serafina Lídia
  • Departamento de Engenharia Química, Faculdade de Engenharia, Universidade Eduardo Mondlane, Maputo, Moçambique.
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Svanberg Ulf
  • Svanberg Ulf
  • Division of Food and Nutrition Science, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden.
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Andlid Thomas
  • Andlid Thomas
  • Division of Food and Nutrition Science, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden.
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  •  Received: 22 September 2022
  •  Accepted: 31 October 2022
  •  Published: 31 December 2022

Abstract

Diet based on whole cereal flours is associated with a high prevalence of iron deficiency anemia and zinc deficiency in low/middle-income countries. Such flours contain high content of phytate that chelates minerals such as iron and zinc, making them unavailable for absorption by humans. To improve the mineral absorption, a phytate:iron molar ratio <1 and a phytate:zinc molar ratio <5 is needed to be achieved. This study aimed to improve the phytate degradation in composite wheat-cassava-whole sorghum flour bread by adding a phytase releasing yeast Pichia kudriavzevii TY13 in baking, preincubated or not, with addition of yeast extract. The phytate and mineral contents were measured by high-performance ion chromatography. Addition of P. kudriavzevii TY13 to the composite flour dough and fermentation for 2 h at room temperature resulted in a 98% phytate degradation. However, the same phytate reduction in the composite bread was achieved after 1 h fermentation at room temperature with addition of preincubated P. kudriavzevii TY13 plus yeast extract. Increasing the fermentation temperature to 30°C, the phytate content was equally low after fermentation for 1 h with P. kudriavzevii TY13 (preincubated or not) plus yeast extract. In conclusion, a faster reduction of phytate in composite bread was obtained by increasing the fermentation temperature, and addition of P. kudriavzevii TY13 (preincubated or not) with added yeast extract. The phytate to iron molar ratio was then 0.2 and the phytate to zinc molar ratio 0.6, which strongly indicates an improved bioavailability of both minerals from such a bread.

 

Key words: Phytate, phytase, Pichia kudriavzevii TY13, yeast extract, wheat flour, cassava flour, sorghum flour, bread making.