Determination of Energy Profile in Processing Cassava (Manihot species) into ‘Gari’ in a Local Oven

Abstract

The dry-frying process is the most critical operation in the processing of cassava (Manihot species) into ‘gari”. The local technique of ‘Garification’ in batch operations was found to be most dependent on prevailing processing temperature with regular agitation. The temperatures of customised fryer was recorded every 3 min of the ‘garification’ process until the process is completed. The moisture content of dewatered 5 kg mash at 40-50%, was reduced to an acceptable moisture content of 12.5% at temperatures in the range of 27–165°C. The energy profile was found to follow a particular profile of dehumidification for the first 7 min, evaporation cooking between 8 to 12 min, drying at about 15 to 22 min and frying for about 5 min before cooling in a 30-35 min batch cycle. A swelling index of 3.4 as a mark of good product was achieved. The moisture content and the temperature were also influenced by the particle size of the mash and the cake density. These series of operation occurred consecutively and are all dependent on the prevailing temperature and duration of treatment. The Energy profile can be used for small and medium scale design, fabrication and processing of cassava to obtain suitable product. It can also form a precept to automation or as a complementary processing technique in an emerging mechanized gari fryer.