Structuring bigels fabricated with high-pressure processed red quinoa hydrogel and carnauba wax oleogel to potentiate thermal and stability characteristics.

Abstract

In this study, a novel functional plant bigel is formulated by integrating high-pressure-processed red quinoa hydrogel with carnauba wax oleogel. Increasing oleogel content up to 50 % enhanced firmness (77.95 g to 477.76 g), spreadability (63.83 g.s to 523.61 g.s), and rheological properties, while decreased the solvent holding capacity (SHC) (99.63 % to 93.29 %). Fluorescence microscopy showed that at low oleogel concentrations, the oleogel particles were dispersed within the hydrogel phase. In contrast, at a 50 % oleogel concentration, a bi-continuous system was observed, where both oleogel and hydrogel phases formed interconnected networks. High pressure (HP) treatment promoted the formation of smaller, more uniformly distributed globules, compared to the untreated flour bigel. Firmness and spreadability values were higher in bigels made with HP treated quinoa (e.g., firmness 396.17 g, spreadability 417.32 g.s for bigels containing 20 % oleogel) compared to those prepared with untreated quinoa, achieving properties that typically require higher fat concentrations in conventional systems. All bigels showed a shear-thinning behaviour, which is crucial to function as a fat replacer as it enhances spreadability during surface application. A strong positive correlation was observed between oleogel content and mechanical properties (firmness-storage modulus: r = 0.90, p < 0.002), while hydrogel fraction correlated with thermal stability and solvent retention capacity (r = 0.85, p < 0.01), enabling predictable formulation design for targeted applications. The study helps to widen the scope of accommodating red quinoa flour as a gelling or thickening agent and introduces HP-assisted bigel systems as promising low-calorie, plant-based solid fat alternatives for the food industry.