Small-scale starch extraction and storage to improve process efficiency

Partners:

SAGOSERVE, India
Private Sector Starch Industries in India.

Problem:

There are over 1000 small scale starch extraction factories in south India providing a significant market for poor cassava farmers.  Two major sets of constraints to the industry, established through process audits were: (a) low efficiency of starch extraction; high water consumption during the processing; and, the adverse environmental problems created from the discharge of effluent from processing units; and (b) quality problems associated with wet starch storage.  Approaches to overcome these constraints were developed and validated.

Achievements:

The use of hydrocyclones were investigated for their application within the process to reduce water consumption and minimise effluent generation.  Trials showed that over 60% of the water used could be re-cycled, which led to a reduction of the total water consumption and the volume and loading of effluent by over 50%.  Whilst there is no financial benefit to be obtained by operating the hydrocyclone, it is recognised that the cost of operation maybe offset by the savings made from extracting water.

The inability to dry all the starch (and sago prepared from the starch) extracted from cassava at the height of the season in India means that up to 40% of annual starch production is stored for 4-5 months.  There is a loss of quality during storage that results in a 20% loss in income.  Field trials have shown that low concentrations of acetic acid (2%) can be used to prevent the growth of microorganisms.  The treatment of starch with 2% acetic acid during storage resulted in a product with viscosity 32% higher than the minimum value specified in the Indian standard for textile starch whereas conventionally stored starch had a viscosity value 14% below the minimum value.  The technology was validated in full scale factory trials and reduced levels of starch loss were demonstrated.