Rotary-moulded biscuits: Dough expansion, microstructure and sweetness perception as affected by sucrose:flour ratio and sucrose particle size

Abstract

Sucrose not only provides sweetness, but also modifies the thermal/viscoelastic behavior of dough during baking. Most research on biscuit manufacturing has been focused on sugar-snap and wire-cut biscuits, and there is a lack of accumulated knowledge with respect to rotary-moulded biscuits. The aim of this study was to analyze the effect of the sucrose:flour ratio and the particle size of sucrose on dough expansion and starch gelatinization during the baking of rotary-moulded biscuits, together with their link to sweetness perception. X-ray micro-CT and scanning electron microscopy were used to ascertain the link between sensory attributes and biscuit structural properties. Image analysis showed that biscuits with lower levels of sucrose resulted in a microstructure with smaller air pores and thinner walls, which may be related to a lower degree of grittiness and hardness at the first bite. Furthermore, the results revealed the partial gelatinization of starch in all formulations, along with a gelatinization degree that increased from 6 % to 40 % as the sucrose content decreased from 40 % to 10 % (d.b.). Interestingly, biscuits that were formulated with powdered sucrose at the highest concentration attained an expanded and non-collapsible structure, a behavior that could be linked to the low degree of starch gelatinization.