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Biological fixation of atmospheric N2 in the initial phase of cassava starch fermentation

The initial phase of natural fermentation of cassava starch presents vigorous fermentation within the first 24 h and is characterized by a high ration of carbon/nitrogen. Consequently, the necessary nitrogen to the formation of biomass would be originated from outside of the system because the available protein content from cassava starch is very low and depending on biological fixation of atmospheric N2. To verify that hypothesis two essays were conducted with the nitrogen balance in the starch granule suspension during the initial 120 h of the fermentation process. The essays were set at room temperature and at the controlled temperature of 28 °C. No increase in the nitrogen content was detected suggesting that no involvement of atmospheric N2. Results suggest that the origin of the nitrogen to the fermentation process is the cassava starch itself. The cassava starch in the flour form possesses high C/N ratio whereas in the aqueous suspension the C/N ratio is lowered propitiating vigorous fermentation.

cassava starch flour form; fermented cassava starch; biomass; nitrogen; C/N ratio; acid lactic bacteria


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