Extrudability and Consolidation of Blends between CGM and DDGS

Abstract EN

During the last decade, the global biofuels industry has experienced exponential growth.

By-products such as high protein corn gluten meal (CGM) and high fibre distillers dried grains with solubles (DDGS) have grown in parallel.

CGM has been shown to be suitable as a biopolymer; the high fibre content of DDGS reduces its effectiveness, although it is considerably cheaper.

In this study, the processing behaviour of CGM and DDGS blends was evaluated and resulting extrudate properties were determined.

Prior to processing, urea was used as a denaturant.

DDGS : CGM ratios of 0, 33, 50, 66, and 100% were processed in a single screw extruder, which solely used dissipative heating.

Blends containing DDGS were less uniformly consolidated and resulted in more dissipative heating.

Blends showed multiple glass transitions, which is characteristic of mechanically compatible blends.

Transmission electron microscopy revealed phase separation on a microscale, although distinct CGM or DDGS phases could not be identified.

On a macroscale, optical microscopy suggested that CGM-rich blends were better consolidated, supported by visual observations of a more continuous extrudate formed during extrusion.

Future work should aim to also characterize the mechanical properties of these blends to assess their suitability as either bioplastic feedstock or pelletized livestock feed.