Development and rheological modeling of dietary fiber and policosanol plant-based bigels for potential food applications

Bigels are composite materials made by two phases with different polarities (i.e., an oleogel and a hydrogel) mixed between them without the addition of emulsifiers. Owing to their versatile rheological properties, they can be used for designing new products for food industry, or for cosmetics and pharmaceutical applications. In the past, different models have been proposed to relate their rheological properties to single phases characteristics and volume fraction. This paper proposes the rheological characterization and modeling of bigels prepared with citrus fiber particle gels (as the aqueous phase) and policosanol-based oleogels by investigating the effects of the ratio between rheological properties of phases and of the dispersed phase volume fraction. Both components (i.e., citrus fiber and policosanol) exhibit interesting properties for preparing plant-based healthy foodstuffs. Rheological characterization was carried out revealing that O/W bigels were formed at low fractions of oleogel added to gelled suspension whereas, at higher fractions, a transition through a matrix-in-matrix systems and, finally, a phase inversion occurred. The trend of phase angle at 1 Hz with oleogel volume fraction was used as a criterion to highlight the phase transition, as confirmed by confocal microscopy. Two models were proposed for predicting the rheological behavior of samples with both phase arrangements.