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Significance of yeasts and moulds occurring in maize dough fermentation for 'kenkey' production
1Alfred Jørgensen Laboratory Ltd., Frederiksberg, Copenhagen, Denmark.
Abstract:
Yeasts and moulds associated with the fermentation of maize dough during the processing of the West African traditional food 'kenkey' were investigated. A mixed flora comprising Candida, Saccharomyces, Trichosporon, Kluyveromyces and Debaryomyces species were isolated from raw maize, during steeping and early phases of fermentation. After 24-48 h of fermentation, Candida krusei and Saccharomyces cerevisiae dominated reaching counts exceeding 10(6) cfu/g. This succession of yeast populations and the significant multiplication of C. krusei and S. cerevisiae were observed in all cases for both the fermentation and the production sites investigated. Penicillium, Aspergillus and Fusarium species, including potential mycotoxin producers, were isolated from raw maize. Initial high counts of 10(5) cfu/g for moulds were reduced to less than 10(2)cfu/g within 24 h of fermentation. High levels of aflatoxins were observed in raw maize, and they were not affected during the fermentations.
Insights
This study investigated yeasts and molds during kenkey fermentation. Candida krusei and Saccharomyces cerevisiae dominated the fermentation, while mold counts decreased significantly, with aflatoxins remaining unaffected.
Area of Science:
- Food Microbiology
- Fermentation Science
- West African Cuisine
Background:
- Traditional fermented foods like kenkey rely on microbial activity for flavor and preservation.
- Understanding the microbial dynamics in kenkey production is crucial for ensuring food safety and quality.
Purpose of the Study:
- To identify and quantify yeast and mold populations during kenkey fermentation.
- To assess the impact of fermentation on microbial load and mycotoxin levels.
Main Methods:
- Isolation and identification of yeasts and molds from raw maize, steeped maize, and fermented kenkey.
- Enumeration of microbial populations using colony-forming units (cfu/g).
- Analysis of aflatoxin levels in raw and fermented samples.
Main Results:
- A diverse yeast flora including Candida, Saccharomyces, Trichosporon, Kluyveromyces, and Debaryomyces was initially present.
- Candida krusei and Saccharomyces cerevisiae became dominant after 24-48 hours, reaching counts over 10(6) cfu/g.
- Mold populations (Penicillium, Aspergillus, Fusarium) initially high on raw maize were reduced by over 99% within 24 hours of fermentation.
- Aflatoxin levels in raw maize remained unchanged throughout the fermentation process.
Conclusions:
- The fermentation process significantly reduces mold counts, contributing to the safety of kenkey.
- Candida krusei and Saccharomyces cerevisiae play a key role in the fermentation of maize for kenkey.
- The stability of aflatoxins during fermentation highlights the importance of controlling raw material contamination.