Microbial Profile and Dynamics of Metata ayib

Abstract

Although metata ayib is widely consumed, there is no scientific report about microbial profile, role of microbes and spices during fermentation. The objective of this study is to investigate microbial profile, role of spices and lactic acid bacteria in metata ayib fermentation.   Metata ayib was prepared from ayib and different spices. Ayib without spice and sterilized ayib with spices were used as controls. Samples were taken periodically within four days of interval to assess the microbial profile fermentation period.  Except lactic acid bacteria, microbial groups were reached their highest counts after the fourth day of maturation and steadily decreased toward the end of the fermentation period.  The counts of the microbial groups in ayib were 10² CFU/g times higher than metata ayib. Metata ayib samples had a total viable bacterial count ranging from 2×10² to 5×10⁸ CFU/g as compared with 2×10⁴ to 5.2×10¹⁰ of ayib. In the first day of sampling, the number of coliforms and Staphylococcus aureus in ayib was equal to 2.5×10⁵ CFU/g and 2.6×10⁴ CFU/g, respectively, but they were not detected in metata ayib at the 20^th day fermentation. The counts of yeast and mould in metata ayib sample were lower than the corresponding values in ayib. Lactic acid bacteria comprised the main microbial groups preset in metata ayib at all sampling days. The pH of metata ayib and ayib was reduced from 6.4 to 4 and 6.92 to 4.3, respectively.  The total absence of coliforms and S. aureus in the metata ayib might be due to sharp drop of pH, antimicrobial activities of lactic acid bacteria (LAB) and an inhibitory effect of the various spices added during preparation of metata ayib.

Keywords: Antimicrobial activities, lactic acid bacteria, metata ayib, microbial profile, spices