Development of oil-in-water emulsion gels enriched with barley β-glucan as potential solid fat substitute and evaluation of their physical properties

Emulsion gels are considered as an innovative approach to substitute shortenings and margarine in food formulations, e.g., bakery products. Cereal β-glucans are fiber-type constituents, well-known for their human health promoting effects, but also as effective viscosifiers for stabilization of emulsions and aqueous dispersions of solid particles. Barley emulsion gels (BEGs) were formulated with varying weight proportions of β-glucan-enriched (∼27%) barley flour/olive oil/water (from 13/10/77 to 31/30/39) and their physicochemical properties and microstructure as potential solid fat replacers in food formulations were examined. Changes in physical properties and structure of BEGs were monitored using dynamic rheometry, large deformation mechanical testing, differential scanning calorimetry and confocal microscopy during storage (4 °C for 7 days). The rheological tests showed a typical solid-like character for all BEGs (i.e., G' was greater than G'') without oil exudation. The gel strength of BEGs increased upon storage, whereas the thermal properties were dependent on composition and application of heat treatment during BEGs production. Moreover, the microstructure of BEGs revealed that protein particles are located around the surface of oil droplets in the 13/10/77 gels, while in the 31/30/39 formulation, both oil droplets and proteins were entrapped within a more compact hydrated β-glucan-starchy network matrix. The molecular weight of β-glucans (SEC-HPLC) isolated from BEGs was lower than that of β-glucan isolate obtained from the native barley flour. Overall, the multi-instrumental analytical approach employed herein was a suitable framework for evaluation of the physical properties of BEGs as potential solid fat substitutes in the production of healthier formulated products. © 2023 Elsevier Ltd