Cellulose cryogel particles for oil structuring: Mixture properties and digestibility

Abstract

This study evaluated the feasibility of using cellulose cryogel particles to structure liquid oil. To this aim, cryogel particles were prepared by grinding and freeze-drying a hydrogel made from a 5% (w/w) microcrystalline cellulose (MCC) dissolved in aqueous NaOH and coagulated in water. Compared to native MCC, cryogel particles presented a more irregular surface, as detected by scanning electron microscopy. The powder of cryogel particles presented low density (0.25 g cm−3), and high porosity (78%). The obtained particles were mixed with increasing quantities of sunflower oil, from 60 to 80% (w/w) oil, and their capacity to entrap oil forming a semi-solid material was determined. While MCC showed no oil structuring capacity, cellulose cryogel particles mixed with 71–74% (w/w) oil resulted in gel-like materials characterized by 100% oil holding capacity. No oil was released upon temperature increase up to 90 °C. The compressive behavior of these systems revealed no yield point, highlighting a non-spreadable deformation behavior. In these conditions, cellulose cryogel particles likely absorbed oil in their pores, while free oil formed capillary bridges allowing particle interconnections without the formation of a plastic network. Based on these considerations, these materials can be regarded as granular solids. The in vitro gastrointestinal digestion showed that oil structuring by cellulose cryogel particles did not affect the kinetics or the extent of fatty acid release. The proposed oil structuring approach opens promising applications of porous cellulose in foods.