Fig. 1.

Set-up of the field-experiments. Panel a In the afternoon the fermentations were started. Active back-slopping was performed using a pipette. The local community showed great interest in the study. b Fermentation was performed in calabashes and plastic buckets, with pH meters and temperature probes attached. At night the containers were put inside the house to prevent temperature drops. c Samples of Mabisi at different stages of fermentation were stabilised on a filter paper