Utilization of mildly fractionated faba bean protein-rich soluble fractions to stabilize lemon-oil-based beverage emulsions against environmental stresses and Ostwald ripening

Beverage emulsions prepared with partially water-soluble flavor oils, such as lemon oil, can be susceptible to Ostwald ripening. This challenge can be overcome by combining a water-insoluble oil with lemon oil in an optimum amount. Functional proteins from faba bean extracted by an aqueous-based mild fractionation process were directly utilized to develop beverage emulsions prepared at pH 3. A three-fold lemon oil was mixed with canola oil in different concentrations (100%, 75%, and 50%), and the oil mixture was used to make 1 wt% oil-in-water beverage emulsions stabilized with a mildly fractionated 0.5 wt% faba bean protein-rich soluble fraction, using a high-pressure homogenizer at pH 3. The long-term stability of the emulsions was determined in the presence of 100 mM NaCl and after heating to 90°C for 30 mins. The initial average droplet diameter of the 75% (0.23 µm) and 50% lemon oil (0.27 µm) emulsions were lower than the 100% lemon oil emulsions (0.48 µm). The rate of Ostwald ripening was estimated from the slope obtained by plotting the cube of mean droplet diameter as a function of time and was compared for each of the emulsions. The salt and heat-treated 100 % lemon oil emulsions exhibited a higher rate of Ostwald ripening corresponding to the increase in mean droplet diameter during storage compared to the other emulsions. The results also imply the role of the protein-rich soluble fractions in controlling the rate of Ostwald ripening or coalescence in all the emulsions.  The findings of this study indicate the superior ability of the mildly fractionated faba bean soluble fractions in stabilizing lemon oil-based emulsions against salt, heat, and Ostwald ripening paving the way for developing sustainable flavor-based beverage products.