Development of low oil emulsion gels by solidification of oil droplets and determination of their rheological properties

Abstract

This study aims to develop low-fat emulsion gels by physically solidifying oil droplets using a combination of pectin, soy protein, and bovine gelatin, and to investigate the rheological properties of these emulsion gels. The emulsion gels were formulated with different combinations of these biopolymers [PSG30 (pectin + soy protein + gelatin + 30% oil), PS30 (pectin + soy protein + 30% oil), P30 (pectin + 30% oil), G30 (gelatin + 30% oil)] and compared with commercially available low-fat mayonnaise (DYM40, 40% oil), mayonnaise (TM80, 80% oil), and spreadable fat (SY59, 59% oil) samples. The consistency index (K, Pa.sn) of the emulsion gels ranged from 1.903 to 150.739 Pa.sn, with PSG30 and PS30 formulations exhibiting higher K values than the commercial samples. The highest structural recovery percentage was observed in the SY59 sample at 114.91%. Thermal stability tests demonstrated that PSG30 and PS30 maintained their viscosity and storage modulus (G') values over a wide temperature range. Fourier Transform Infrared Spectroscopy (FTIR) analysis revealed significant hydrogen bonding and cross-linking interactions between pectin, soy protein, and gelatin. Microstructural imaging showed that PSG30 had the most homogeneous structure, consistent with its superior rheological performance. Molecular docking analysis determined the binding energy between gelatin and pectin to be -6.40 kcal/mol. Interaction between pectin (Arg-522 residue) and soy protein (11S globulin TGT) was facilitated by salt bridge formation. The developed formulations of pectin, soy protein, and gelatin demonstrate potential for producing low-fat emulsion gels with acceptable texture and stability properties for various food applications.