FERMENTATION AND BAKING REDUCED AFLATOXIN B1 RETENTION OF WHOLE WHEAT FLOUR LEAVENED WITH SACCHAROMYCES CEREVISAE ISOLATED FROM SOME CEREAL BASED FERMENTED FOODS

Abstract

Aflatoxins are the most common occurring mycotoxin and most potent hepatocarcinogen known to mammals. The aim of this research was to isolate Saccharomyces cerevisae from cereal based fermented foods (ogi, madidi and kunun-zaki) for leavening bread and to study aflatoxin B₁ reduction potential of solid state fermentation and baking of whole wheat flour dough into leavened bread. Proximate values were determined using standard techniques. While alpha amylase activity of the whole wheat flour was determined by Hagberg falling number (HFN), the viscoelastic property and dough strength of the flour was determined using Chopin alveograph. Enzyme Link Immunosorbent Assay technique was employed to detect and quantify aflatoxin B₁ from the samples. The alpha amylase of the whole wheat flour was 240 seconds, while the viscoelastic property of the flour was 230 joules. The aflatoxin level during fermentation of the wheat flour dough showed that within 60, 90 and 120 minutes of fermentation at 35±2^oC/2 h, the percentage aflatoxin loss increased as follows; 10.3. 34.5 and 55.2 % respectively. Conversely, the total aflatoxin retention decreased in this order; 89.7, 65.5 and 44.8% respectively. As the fermentation time increased, the percentage aflatoxin loss increased and the percentage aflatoxin retention decreased. The baking profile of the fermented dough also showed that as the baking temperature increased from 180, 200 and 220^oC the aflatoxin loss increased from 58.6, 62.1 and 72.4 %  and the aflatoxin B₁ retention also decreased 41.4, 37.9, and 27.6% respectively. Fermentation and baking of whole wheat flour indicated that more than half of the toxin was eliminated but, some miniatures of toxins were still present in the fermented dough and the baked bread. This study showed that the Saccharomyces cerevisiae isolated from ogi has strong potential for leavening and was comparable to the commercial baker’s yeast. The use of wholesome raw material for bread production is advocated, because, the left over miniatures of aflatoxin in the finished products could be a health threat to consumers of bread produced from contaminated whole wheat flour.