Assessment of legume starches to determine rheological characteristics relevant to alcohol production

In the production of any alcoholic beverage you must understand the starch present and how to degrade it (via gelatinisation, liquefaction and saccharification) to simple sugars that are usable by yeast.  Through using a RVA and a new rheometer method the gelatinisation temperature of a raw materials starch has been identified.  This is the point where starch granules have become swollen with water and burst open to release their starch into solution thus making it available for enzymatic breakdown.  This temperature point is specific to the raw material being used and is critical in producing a fermentable feedstock.  This method can further be used to assess the success of different enzyme additions on starch breakdown; with a decrease in viscosity indicating successful enzymatic breakdown.

Samples are milled to produce a fine grist.  A fixed amount of the grist is then used to form a slurry with a calculated weight of water and run on a pre-set rheometer programme.  The programme consists of an initial rapid stir followed by continuous stirring as temperature is increased, held, then decreased. The rheometer software then produces a chart output of the viscosity over time from which conclusions such as starch gelatinisation temperature, enzyme activity etc can be drawn.