Stability of pea protein-MCT oil emulsions with sucrose fatty acid esters

The techno-functionality of plant proteins has been widely studied due to their low cost and low impact on the environment in comparison to animal proteins. In regards to emulsion stabilization, plant proteins may require the use of surfactants to assist in oil-in-water emulsion formation while minimizing droplet flocculation and coalescence. Sucrose fatty acid esters (SE) are non-ionic surfactants that contain a hydrophilic sucrose group and a fatty acid hydrophobic moiety used in a variety of food applications. This work focused on the stabilization of MCT oil-in-water emulsions using pea protein and the SEs S-570 and P-1670 (HLB 5 and 16, respectively). Initially, a base emulsion (20 wt% MCT oil, 4 wt% pea protein concentrate) was prepared at 65°C using a rotor-stator (5,000 rpm, 10 min) and homogenized (20 MPa, 1 cycle). The base emulsion was diluted with sucrose ester solutions with a final composition of 6 wt% oil, 1.2 wt% protein, and 0-0.25 wt% of each SE. After dilution, the emulsions were mixed for one minute in the rotor-stator at 5000 rpm, homogenized (20 MPa, 2 cycles), and sterilized (30 minutes, 121°C). Emulsions were stored at room-temperature (20 °C) and 35 °C for up to eight weeks. The volume-weighted average emulsion droplet size before sterilization was ~0.3 mm for the control and ~0.2 mm with the addition of surfactants. Backscattering and Turbiscan Stability Index (TSI) indicated moderate instability. Emulsions prepared with 0.20 wt% or more of of P-1670 and store at 20 °C presented a smaller TSI when compared to the control indicating stability improvement. The visual appearance of the emulsions did not change after sterilization or over time. Viscosity results also indicated minor changes after sterilization and during storage. These results indicated that the P-1670 at concentrations 0.2 wt% or more enhanced the stability of pea protein-MCT oil-in-water emulsions.