Rheological and Physicochemical Properties of Oleogel with Esterified Rice Flour and Its Suitability as a Fat Replacer

Abstract

The objectives of this study were to produce oleogel using esterified rice flour with citric acid (ERCA), to evaluate physicochemical and rheological properties of oleogels, and to investigate their suitability as a fat replacer. Rice flour was esterified with citric acid (30%, <i>w</i>/<i>w</i>) to produce ERCA. Emulsions and oleogels were prepared with different concentrations (0, 5, 10, and 15%, <i>w</i>/<i>w</i>) of ERCA. In the steady shear rheological analysis, it was found that the values of apparent viscosity (<i>η</i>_a, 100) and consistency index (K) of emulsions were significantly increased by increasing the concentrations of ERCA. Oleogels were prepared with different concentrations (0, 5, 10, and 15%, <i>w</i>/<i>w</i>) of ERCA. All oleogels showed a hydrophobic carbonyl bond in the Fourier transform infrared (FT-IR) spectra. The peaks on new hydrogen bonds and amorphous regions, which did not appear in oleogel prepared with 0% ERCA, were observed at 3300-3400 cm^-1 and 1018 cm^-1, respectively, in oleogels prepared with ERCA. With the increase in ERCA concentrations in oleogels, oil loss values were significantly decreased. In a time-dependent test, it was found that all oleogels exhibited thixotropic properties. The frequency sweep test revealed that storage modulus (G'), loss modulus (G″), and complex viscosity (<i>η</i>*) values of oleogels were elevated with an increase in the concentration of ERCA. Oleogels prepared with 15% ERCA exhibited the lowest peroxide, <i>p</i>-Anisidine, and Total Oxidation(TOTOX) values. The addition of oleogels to cookies did not considerably affect appearance. However, it increased the content of unsaturated fatty acid. These results indicate that oleogels prepared with ERCA can be used as a fat replacer in food industry.