Investigation of the foaming and encapsulation properties of whey proteins

Foamed foods have been present for years and play an important role in the food we eat, e.g., in bread, carbonated drinks (e.g., beer), ice cream etc. Although aeration offers little nutritional benefit it provides foods with different textures and the air bubbles can help with digestion. However, foams are thermodynamically unstable and must be stabilised for consumer acceptance and product shelf-life. This work looked at creating stable foams using whey protein isolate (WPI). Whey protein being amphiphilic, can stabilise foamed systems by residing at the air/water interface. Preliminary data found that WPI had good overrun but was unstable and drained within 1–48 h. Due to this instability, WPI microgels were prepared via cold-set gelation and their foamability was assessed, known as Pickering stabilisation. The microgels had lower overrun compared to native WPI, however, stability was much greater than native WPI. The microgels created self-supporting ultra-stable foams, remaining stable for >2 years. In addition, microgels can also encapsulate compounds. In this work, the microgels encapsulated vitamin D3 (VD3), protecting it from stresses found in the food industry such as pasteurisation, UV-light and long-term storage. To the authors knowledge, there has been no published work based on using WPI microgels for encapsulation while also producing stable foams. This project proved that WPI microgels can simultaneously encapsulate VD3 while also forming an extremely stable foam. Having established good foaming and encapsulation, the VD3 loaded WPI microgels (WPI/VD3) were incorporated into ice cream, whereby the melting rate was significantly reduced. Addition of WPI/VD3 microgels to ice cream did not negatively affect the ice creams properties and VD3 content remained stable, indicating the protective effect of WPI microgels from processing and storage conditions. This demonstrated that WPI microgels could form ultra-stable foams, while acting as a delivery vehicle for VD3 for food fortification