Impact of traditional processing conditions and methods on the aflatoxin content of cooked maize

Abstract

The traditional cooking of dry maize grain for preparing either boiled maize (nifro) or roasted maize (qollo) in Ethiopia is preceded by soaking dry maize in water for a certain time. This study aimed to assess the practice of soaking dry maize grain and determine the effect of soaking water volume (0, 200 or 300 ml per 100 g), soaking time (12 or 48 h), soaking water temperature (warm or cold water) and type of cooking method (boiling and roasting) on the aflatoxin content of traditional Ethiopian cooked maize, nifro and qollo. The survey and laboratory experiments used semi-structured interview questionnaire and fractional factorial design, respectively. Aflatoxins were extracted from aflatoxigenic Aspergillus flavus spores inoculated onto raw maize, soaked in water and finally cooked by boiling or roasting of the soaked maize grain. Cleanup was done using Immuno Affinity Column and analyzed using Ultra High Performance Liquid Chromatography with fluorescence detector. Soaking dry maize grain in excess water (300 ml water/100 g maize) varying the soaking water temperature and duration before boiling and roasting had resulted in significant total aflatoxin reduction (p < .05) ranging from 33.6% to 89.9% in boiled maize and more than 89% in roasted maize compared to the control. The study results indicated that roasting of soaked maize grain resulted in a considerably lower aflatoxin content compared to boiling of soaked maize grain. Dry maize grain soaking in excess water and cold water before cooking showed a better reduction of aflatoxin.

Keywords:

• Aflatoxin
• boiled maize
• maize based food processing
• nifro
• qollo
• roasted maize

REVIEWING EDITOR:

• M. Luisa Escudero-Gilete, Universidad de Sevilla, Spain

SUBJECTS:

• Agriculture and Food; Food Chemistry; Food Engineering

Acknowledgments

The authors thank Ethiopian Institute of Agricultural Research (EIAR) for the financial support to this research. The authors would also like to thank survey study participants, Holeta Agricultural Research Center, Holeta, Ethiopia, for the provision of research laboratory, as well as Ethiopian Conformity Assessment Enterprise laboratory, Addis Ababa, Ethiopia, for the total aflatoxin content analysis.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Data will be made available on request.

Additional information

Notes on contributors

Habtamu Gebremichael Daba

Habtamu Gebremichael Daba, is a researcher at the Ethiopian Institute of Agricultural Research in the Food Science and Nutrition research sector, based at Kulumsa Agricultural Research Center, Asella, Ethiopia.

Mulugeta Admasu Delele

Mulugeta Admasu Delele (currently an Associate Professor), Solomon Workneh Fanta (Professor), Nigus Gabbiye Habtu (Professor), and Metadel Kassahun Abera (currently an Associate Professor) work at Bahir Dar University, Institute of Technology, Bahir Dar, Ethiopia, and have immense experience in research and teaching at the faculty of chemical and food engineering.