Effect of the use of sweet potato or chayote tuber starch hydrogels on the physical properties of oleogel-in-hydrogel (bigels) systems

Bigel systems (BG) were formed through the combination of an oleogel (OG) formed with canola oil and beeswax (5% wt.), and a hydrogel (HG) formed with sweet potato (SP) or chayote tuber (CH) starch (10% wt.), using three OG : HG ratios (30:70, 40:60, 50:50). All the BG were self-standing, exhibiting uniform and well-defined phase distribution of OG-in-HG, and oil-binding capacities greater than 96%. Droplet size of BG was influenced by the OG : HG ratio; higher amount of OG produced smaller droplet sizes. The characterisation of BG by FTIR and XRD showed structural configuration in BG is driven by physical and steric interactions by displaying distinctive characteristics of each individual phase and dismissing the formation of novel bonds. BG showed a pseudoplastic behaviour and was characterised as a weak gel, G ' > G '' at strains below 100% for BG(SP) and 50% for BGCH, with a shifting process (G ' > G '' ) at higher strains. Viscoelastic properties were influenced by the OG : HG ratio where BG at 50:50 exhibited lower strength and resistance to deformation. Textural parameters in BGSP were higher than BGCH, and influenced by the OG : HG ratio, indicating that the phase proportion in BG can modulate its structure and performance.

Automated summary

Bigel systems were formed by combining an oleogel formed with canola oil and beeswax, and a hydrogel formed with sweet potato or chayote tuber starch. The self-standing BG exhibited uniform phase distribution and high oil-binding capacities. The droplet size and viscoelastic properties of BG were influenced by the OG : HG ratio.