356: Zein-Based Oleogels: Oil Type Impact on Functionality in Plant-Based Fat Alternatives

Introduction

One promising approach for producing plant-based fat alternatives is oleogelation, a physical technique that restructures liquid oil into an irreversible viscoelastic gel. While zein-based oleogels have gained increasing attention for food applications, the structural, thermal, and mechanical properties of food-grade oleogels in relation to oil type remain insufficiently explored. This study aims to evaluate the impact of different oils on zein-in-glycerol oleogels to better understand their behavioral stability and performance in processed food systems.

Methods

Zein was dissolved in glycerol and shear-homogenized using five different oils: canola, soybean, vegetable, fractionated coconut, palm, and olive oil. The prepared oleogels were evaluated for their oil- and solvent-holding capacities. Structural, thermal, and mechanical properties were assessed using differential scanning calorimetry (DSC), texture profile analysis (TPA), colorimetry, and rheological analysis, including amplitude, frequency, and temperature sweeps.

Results

The study demonstrated that surface hydrophobicity and solvent-holding capacity of zein-in-glycerol oleogels were influenced by oil type, likely due to variations in interfacial tension with zein. Solvent-holding capacity varied widely, with soybean oil-based oleogels achieving the highest value (81.51%) and palm oil-based oleogels showing the lowest (67.97%). Rheological analysis confirmed shear-thinning behavior across all formulations, with soybean oil-based oleogels exhibiting superior elastic resilience at higher strains. Palm oil-based oleogels exhibited the highest gel strength (63.90 ± 6.79 g), rupture force (377.3 ± 6.72 g), and adhesiveness (-64.71 ± 6.63 g). DSC analysis indicated semi-crystalline behavior, with saturated oils crystallizing at higher temperatures, suggesting stronger intermolecular interactions with zein. At freeze-thaw temperatures, fractionated coconut oil-based oleogels exhibited the highest enthalpy of crystallization (33.41 ± 2.5 J/g), while oleogels formulated with unsaturated oils showed delayed phase transitions. Visually, soybean oil-based oleogels showed the most pronounced green tint.

Significance

This study advances our understanding of how oil type influences the structural, thermal, and mechanical properties of zein-based oleogels. By identifying oils that best meet desired textural and stability requirements, this research supports the development of innovative applications for zein oleogels in processed food systems. Further research is recommended to explore the applicability of these formulations for targeted foods.

Authors: Elen L Huang, Oguz K. Ozturk