African Journal of
Food Science

  • Abbreviation: Afr. J. Food Sci.
  • Language: English
  • ISSN: 1996-0794
  • DOI: 10.5897/AJFS
  • Start Year: 2007
  • Published Articles: 984

Full Length Research Paper

Effects of different purities of calcium hydroxide on nutrient composition and reduction of aflatoxin and fumonisin in maize and maize-based food

Charles Mannara
  • Charles Mannara
  • Department of Food Science, Nutrition and Technology, University of Nairobi, P. O. Box 29053-00625, Kangemi, Kenya.
  • Google Scholar
Lucy Gicuku Njue
  • Lucy Gicuku Njue
  • Department of Food Science, Nutrition and Technology, University of Nairobi, P. O. Box 29053-00625, Kangemi, Kenya.
  • Google Scholar
George Ooko Abong
  • George Ooko Abong
  • Department of Food Science, Nutrition and Technology, University of Nairobi, P. O. Box 29053-00625, Kangemi, Kenya.
  • Google Scholar


  •  Received: 29 July 2024
  •  Accepted: 15 October 2024
  •  Published: 31 October 2024

Abstract

Mycotoxin contamination in maize remains a significant issue in Kenya. Nixtamalization, a chemical detoxification method, has been employed to reduce aflatoxin and fumonisin levels in maize. Despite its long-standing use, the uptake of nixtamalization in Kenya is limited due to the lack of high-quality Ca(OH)?. The available lime in the market has a purity of only 85%. Therefore, this study aimed to assess the effectiveness of different lime purities in nixtamalization. Maize and githeri samples were collected from 128 schools in Turkana County and tested for aflatoxins and fumonisins. The contaminated samples were treated with varying concentrations of 97 and 85% pure food-grade lime, with different soaking and cooking times. The results were analyzed using SAS software, version 9.4. The different concentrations of 97% pure Ca(OH)? (0-2.5% w/w) successfully reduced aflatoxins by 9 to 72% in maize and 11 to 74% in githeri. In contrast, 85% Ca(OH)? reduced aflatoxins by 6 to 66% in maize and 3 to 74% in githeri. Both purities showed no significant difference in their efficacy in reducing fumonisins, with 97% pure Ca(OH)? achieving a reduction of 2 to 71% in maize and 6 to 66% in githeri. Meanwhile, 85% pure Ca(OH)? reduced fumonisins in maize by up to 79% and in githeri by up to 73%. The proximate composition of the samples was not significantly affected (p<0.05) by either purity, except for ash content, which was higher in samples treated with 85% Ca(OH)?. Although 85% Ca(OH)? shows potential for use in nixtamalization, higher concentrations may be necessary, and further sensory analysis of the final product should be conducted.

 

Key words: Calcium hydroxide, purity, nixtamalization, aflatoxin, fumonisin.