The effect of mono-diglycerides on the mechanical properties,
microstructure and physical stability of an edible rice bran wax --
gelatin biphasic gel system
Abstract
Bigels, are prepared by homogenization of an organogel and hydrogel.
Bigels can offer improved properties when compared to other gelled
systems due to its semi-solid internal phase and supramolecular
interactions between components. The objective of this study was to
determine the effect of mono-diglycerides (MDG) on the supramolecular
structure and interactions, physical stability and mechanical properties
of a rice bran wax (RBW)–gelatin bigels. The organogel-to-hydrogel
(OG:HG) ratios tested were 60:40, 70:30 and 80:20 with MDG incorporated
at four concentrations (0.5, 1, 2, 3% (w/w)). Bigels were analyzed
using nuclear magnetic resonance spectroscopy (NMR), confocal scanning
laser microscopy (CSLM), Fourier transform infrared spectroscopy (FTIR),
texture analysis and liquid binding capacity studies. The results showed
that MDG have a dual effect on the structural organization and stability
of the systems; they act as emulsifiers and/or crystallization
modifiers. CSLM and FTIR showed that the addition of MDG had the
greatest effect on the microstructure of the 60:40 OG:HG ratio, where
MDG concentrations 0.5 and 1% (w/w) exhibited a reduction in the size
of the oleogel regions while concentrations 2 and 3% (w/w) showed a
phase inversion. MDG addition resulted in a gradual decrease in bigel
hardness, but an enhancement of physical stability.