Tailoring the morphology and properties of starch aerogels and cryogels via starch source and process parameter.

Porous starch materials with various morphology and properties were made via starch dissolution, retrogradation and drying either with supercritical CO2 ("aerogels") or lyophilisation ("cryogels"). Their properties were correlated with the rheological response of retrograded starch gels and crystallinity of aerogels and cryogels. All starch cryogels possess very low density (0.07 - 0.16 g/cm3), very large macropores and low specific surface area (around 3-13 m2/g). Their morphology is mainly the replica of sublimated ice crystals. The properties of starch aerogels strongly depend on starch source: the lowest density (around 0.1 g/cm3) and highest specific surface area (170-250 m2/g) was recorded for pea starch aerogels and the highest density (0.3-0.6 g/cm3) and lowest specific surface area (7-90 m2/g) for waxy maize starch aerogels. The morphology and properties of starch aerogels are interpreted by amylose and amylopectin evolution during retrogradation.