2.3. Preparation of oleogels and emulgels
Oleogel preparation followed parameters set forth elsewhere with modifications (Willett & Akoh, 2019). Oleogels were developed in triplicate by dissolving either monolaurin or MAG/DAG in 10 g of algal oil at 90 °C. Oleogels were prepared with concentrations of 8, 10, or 12% gelator (w/w). Gel mixtures were stirred constantly for 10 min until fully dissolved and then transferred to Ace Glass vials purchased from VWR (Radnor, PA, USA). Samples were flushed with nitrogen using an Organomation 12-position N-EVAP (Organomation Associates, Inc., Berlin, MA, USA) and placed at 4 °C to develop the gel network and to store for further analysis. All oleogel treatments were prepared in triplicate.
Emulgels were prepared by first developing emulsions following steps from previous studies (Hyatt, Zhang, & Akoh, 2021). Emulsions were made in bulk using a U.S. Solid 600W Ultrasonic homogenizer (U.S. Solid, Cleveland, OH, USA) with a 13 mm probe for 10 min with a 3 sec on/off pulse method at 80% power. Temperature was controlled using a Cole-Parmer® Polystat® digital refrigerated circulating water bath (Cole-Parmer, Vernon Hills, IL, USA) set at 1 °C. Emulsions were made within a double-jacketed reaction vessel to allow for a stable temperature throughout the homogenizing process, which was monitored and kept at 1 °C (± 0.1 °C).
Once bulk O/W emulsions were developed the preparation of emulgels followed parameters from another study with slight modifications (Chang, Hu, Huang, Hseih, & Ting, 2020). Emulgels were developed by dissolving either monolaurin or MAG/DAG mixture at 8, 10, and 12 % gelator (w/w) with 10 g of emulsion. Once dissolved, emulgel mixtures were then placed in the same type of glass vials as oleogels and flushed with nitrogen in the same manner as oleogels. Mixtures were then stored at 4 °C to set the gel and to store for further analysis. All emulgel treatments were prepared in triplicate.