3.5. Texture Analysis
Texture analysis was performed to determine how mechanical properties of the sample were affected with the addition of MDG. Table 1 shows values for hardness, springiness and cohesiveness for 60:40 and 70:30 OG:HG bigel formulations. Additional texture anlaysis parameters are shown in Table S1. Hardness is shown to significantly decrease with the addition of MDG for both OG:HG ratios with 3% (w/w) MDG having the lowest hardness values. This is an unexpected finding since analysis of SFC (Fig. 4) showed increased SFC with the addition of MDG. With an increased SFC, it is expected that the hardness would increase due to more solids and structure in the sample. Instead, even with the addition of more solids, there is a clear and significant decrease in sample hardness. These results agree with previous studies, where the addition of high proportions of monoglycerides were found to decrease the hardness and/or mechanical strength of various gel systems (Rodriguez-Hernandez, 2021; Toro-Vazquez et al., 2013; Du et al., 2021). The amount of monoglycerides that were needed to cause this effect is dependent on the components of the system. Comparing the highest and lowest MDG concentrations for the 60:40 and 70:30 OG:HG ratios, the average hardness decreased by 68% and 31%, respectively. This data provides evidence of MDG playing the role of lipid modifier and/or a co-crystallizer in the oleogel phase. RBW, when forming an oleogel, is known for its effective needle-like or fibrous crystals that interact and form a matrix to entrap large amounts of oil (Blake et al., 2014; Dassanayake et al., 2012). The crystal size grows proportionately with RBW concentration and correlates to an increased hardness (Dassanayake et al., 2012). The addition of MDG may be interrupting the interactions between RBW crystals or inhibiting crystal growth size, causing the hardness of the gel to decrease as discussed with SFC results (Fig. 4). MDG can also act as seeds for nucleation and accelerate the crystallization process, as mentioned before (Ribeiro et al., 2015). This process can also inhibit crystal growth size. This decrease in hardness may be related to a decreased in crystal-crystal interactions in RBW which are known to strengthen the RBW organogel matrix (Blake et al., 2014; Dassanayake et al., 2012).