Product density: The product density was determined by the
poppy seed displacement method applied to 1 l of extruded products
(Brennan et al., 2008). Variation in the product density of the
product is largely dependant on the proportion of voids or bubbles
that were trapped in the extruded products as they solidified from
the extruder. The product density is expected to be correlated with
the void fraction of the products, hardness and general consumer
acceptability of the product. All measurements are reported as a
mean of between three and five replicates.