The presence of insoluble components greatly minimizes the potential application of pulse proteins in beverage emulsions. Therefore, pea protein concentrate was mildly fractionated by aqueous centrifugation at 4,000g for 1 min to recover a soluble fraction (71% protein yield), which was then used to develop 5% oil-in-water emulsions using a high-pressure homogenizer. Emulsion stability was tested by heat treatment (90°C, 30 min) in the presence of NaCl (0-1M) at pH 7.0 and 2.0. Stability increased upon adding salt at pH 7, while at pH 2, proteins and droplets aggregated. Heat treatment led to extensive aggregation at both pH values due to denaturation and aggregation of proteins at the oil droplet surface, which was further worsened by salt. To prevent thermal destabilization, the proteins were heat-treated at 75°C for 30 min for partial denaturation before emulsification under hot conditions. The heat-treated protein-stabilized emulsions at pH 7 had superior thermal stability at all salt concentrations without aggregation. However, a similar improvement in stability was not observed at pH 2. Pre-heating the soluble protein exposed the hydrophobic patches, leading to better adsorption on the droplet surface, which did not show additional aggregation upon further heating the emulsions at pH 7. The heat-treated protein-stabilized emulsions showed about a 44% drop in lipid digestibility compared to the original emulsions. The proposed approach could be a valuable addition to the utilization of pea proteins in developing beverage emulsions that could withstand the heat treatment used during food processing.

Glycerol monooleate (GMO)-stabilized liquid water-in-vegetable oil (W/VO) emulsions are difficult to stabilize due to the desorption of GMO from the W-VO interface towards the oil phase. This work improved the stability of GMO-stabilized liquid 20 wt% water-in-canola oil (W/CO) emulsion by modifying the dispersed aqueous phase composition with hydrogen bond-forming agents. As a control, 20 wt% water-in-mineral oil (W/MO) emulsion was also utilized. Different concentrations of hydrogen bond-forming agents (citric acid (CA), ascorbic acid (AA), low methoxyl pectin (LMP)) with and without salts (sodium chloride (S) or calcium chloride (Ca)) was added to the aqueous phase before emulsification, which enhanced emulsifier binding to the water-oil interface. The emulsions were characterized by phase separation, stability against accelerated gravitation, microstructure and rheology. W/CO emulsion without any aqueous phase additive destabilized instantly, whereas W/MO emulsion stayed stable. The addition of hydrogen bond-forming agents and salts significantly improved emulsion stability. LMP, with many hydrogen bond-forming groups, was able to provide the highest emulsion stability after 7 days in both oils compared to AA, CA and their mixtures with S. Emulsions with both oils formed weak gels with viscous and elastic characteristics due to the formation of an extensive network of water droplet aggregates. Overall, the hydrogen bond-forming agents interacted with GMO at the interface, thereby improving their presence at the water droplet surface, allowing significantly improved stability of GMO-stabilized liquid W/CO emulsions. The knowledge developed in this research can be useful in applying GMO in stabilizing liquid water-in-oil emulsion without using any crystal network.

Oleogels prepared from hydrocolloids have recently gained a lot of attention as an alternative for trans and saturated fats. Previously we have demonstrated that the freeze-dried foams prepared using a mixture of 5% faba bean or pea protein concentrates with 0.25% xanthan gum at pH 7 and 9 can hold canola oil 30-40 times their weights (Mohanan, Tang, Nickerson and Ghosh, 2020). However, the oleogels suffered from high oil loss, about 30% oil leaked, which negatively affected the rheological properties of the oleogels. The functionality of the cake baked using the oleogels was poorer compared to a shortening baked cake. The present study explored the addition of a small amount of high-melting monoacylglycerol (MAG) and candelilla wax (CW) on reducing oil loss, improving rheological properties and baking qualities of pulse protein-stabilized oleogels. Different concentrations (0.5-3%) of MAG or CW were dissolved in canola oil at 80 ºC. The hot oil was then added into the freeze-dried protein-polysaccharide foams (pH 7) and quickly transferred to a refrigerator. The crystallized additives reinforced the oleogel network, thereby reducing oil loss while increasing the firmness, cohesiveness, and storage modulus. When model cakes were baked with the oleogels, significant improvement in textural properties was observed with the addition of MAG in the foam-templated oleogels. However, in comparison with shortening-based cakes, oleogel-based cakes still showed a negative effect on hardness, chewiness and cohesiveness.