Development and characterization of the freeze-thaw and oxidative stability of edible rice bran wax-gelatin biphasic gels

Edible biphasic gels with high lipid fractions (>50%) were developed and characterized for their freeze-thaw and lipid oxidation stability. Gels consisted of gelatin in aqueous buffer (hydrogel; HG), and rice bran wax (RBW) in high-oleic soybean oil (oleogel; OG). Freeze-thaw stability was studied by rheology, liquid loss measurement, and microstructural characterization of the gels before and after one freeze-thaw cycle. Biphasic gels were stored for 6 months under accelerated oxidation conditions to assess oxidative stability through peroxide value (PV) analysis. Biphasic gels led to superior systems compared to control OG and HG. The storage modulus (G′) increased with increasing OG. Yield stress (σ*) for biphasic gels were greater than for OG alone, and σ*increased as the proportion of HG increased. Micrographs of biphasic gels showed OG-in-HG matrix for all gels, including those of >50% OG. After one freeze-thaw cycle, biphasic gels had less total liquid loss by approximately 50% compared to the controls and showed an increase in G′. No samples were rancid after the storage period, as demonstrated by the low PV (<3 meq/kg). Changing the ratio of OG:HG for this biphasic gel demonstrates the potential to design semi-solid fat replacers of desired properties with good overall physico-chemical stability.