3.1. Bigel Appearance
The successfully prepared bigel samples were evaluated based on their appearance after gelation. Bigels were classified as successful if they were opaque, white and showed no signs of phase separation. Fig. 1 shows the 60:40 and 70:30 OG:HG bigel formulations cut into a cylinder shape. 80:20 OG:HG formulations (not shown) could not be stabilized and showed phased separation immediately after preparation despite the addition of MDG. For this reason, 80:20 OG:HG were excluded from further testing. Most of the formulations for 60:40 and 70:30 OG:HG were successful with the exception of 70:30(3) as can be observed in Fig. 1. The 70:30(3) bigel formulation resulted in phase separation, whereas the control, 70:30(0), showed excellent physical stability. With an increase in MDG concentration, going from 0% to 3%, the bigel became more malleable for both 60:40 and 70:30 OG:HG ratios. The presence of MDG creates a softer, more pliable bigel without altering the visual appearance from the control and without the use of a large amount of hydrogel which can be beneficial for applications where more lipidic phase is desirable. The fact that MDG creates a softer, more malleable bigel may be attributed to MDG being a known lipid modifier (Ribeiro et al., 2015; Alfutimie et al., 2016). It can be hypothesized that MDG may have a dual effect on the bigel system, serving as both a lipid modifier in the lipid phase and an emulsifier at the aqueous-lipid interface.