Unraveling the Wide Variation in the Thermal Behavior of Crystalline Sucrose Using an Enhanced Laboratory Recrystallization Method

Recently, we found that sucrose from beet sources exhibited only one large endothermic DSC peak, whereas sucrose from most cane sources exhibited two peaks. Thus, our objective was to unravel the cause of this wide variation in thermal behavior by investigating both commercial and recrystallized sucrose samples, using a variety of analytical techniques, including DSC, HPLC, SXRD, and Micro-CT. With the aid of recrystallization method enhancements and compositional changes, sucrose crystals were intentionally altered to produce a variety of thermal behaviors, including DSC curves exhibiting one or two endothermic peaks or a single peak with either a low (144 °C) or a high (190 °C) Tmonset value. SXRD results for all sucrose crystals studied were consistent with the known structure of sucrose. Thus, polymorphism is not the cause of thermal behavior variation, but rather, the variation is attributed to the influence of occlusion composition and chemistry on thermal decomposition. Micro-CT supported this assertion by revealing the development of large cavities within the sucrose crystal during heat treatment when occlusion composition and chemistry was conducive to thermal decomposition (e.g., low ash content and pH), but showed impeded cavity formation when occlusions contained inhibitory attributes (e.g., high ash content, sulfite, or water removal via grinding).