Stress relaxation behavior of corn distillers dried grains with solubles (DDGS) in relation to caking

Interaction of DDGS with the environment causes logistical challenges during handling and transportation, and leads to final product quality loss which is currently a major hurdle in marketing DDGS. Understanding the caking behavior of DDGS is one of the major unsolved problems that impacts the logistics and marketability of DDGS. Moisture content, temperature, compression force and time of consolidation influence the mechanical properties of powder materials by stimulating stickiness and eventual caking of bulk powders. The effect of these variables on stress relaxation behavior of DDGS was studied. The bulk density of DDGS increased in the range of 40–50% by compression which indicated the reduction in interparticle distance that would cause potential flow problems due to compression. The solidity values decreased with increase in moisture content implying higher cohesion between the DDGS particles. The relatively high asymptotic residual modulus for low moisture content samples indicated the recoverable compressive work and the degree of elasticity which aids to make the bulk solid flow. The results from this study show that dry (< 10%, w.b.) DDGS bulk flowability will reduce its caking propensity and is better than high moisture (> 13%) DDGS which is cohesive.