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).