Effect of starch type and chitosan supplementation on physicochemical properties, morphology, and oil structuring capacity of composite starch bioaerogels

Oleogelation is a novel fat structuring method for converting liquid oils to solidified oil to reduce trans-fatty acids and saturated fat content in food formulations. In the current study, the impact of starch type and chitosan addition on the oleogelation capacity of aerogels obtained from supercritical CO2 drying technology was investigated. The starch hydrogel precursors were prepared from dent starch (27% amylose content), 55% amylose, and 72% amylose starch in the presence of 0, 0.50, and 0.75 wt% chitosan. The starch type showed a significant effect on the characteristics of resulting aerogels, where aerogels with higher content of amylose showed significantly lower shrinkage and density and higher specific surface area and macroporosity. Furthermore, chitosan addition substantially decreased the shrinkage of the aerogels, particularly those prepared with the dent starch, resulting in aerogels of lower density and higher surface area and macroporous volume. These aerogels were then powdered and employed as oil-absorbing porous materials for structuring soybean oil. Results showed that the aerogels from 55% amylose and 72% amylose starch had better oil structuring capacity compared to those from the dent starch. Furthermore, the starch aerogels supplemented with chitosan showed superior oil structuring ability than the neat starch aerogel counterparts. This work suggests that the starch type and the presence of chitosan had deep impacts on the macroporosity of the starch aerogels and their oil structuring performance.