Microbubbles have the potential to be used in many applications in different fields, especially in food, biomedical, and environmental sciences. However, to produce microbubbles with relatively long-term stability is difficult as they are inherently unstable entities. Hydrophobins are naturally occurring proteins that have previously been shown to have an ability to stabilize micron-sized air cells. More recently, small air cells with other cysteine-rich proteins such as bovine serum albumin and egg albumen (egg white protein) have been constructed using a sonochemical method. The majority of the air cells had a diameter between 1 and 10 μm. A dependence of the air cell size and stability with the processing conditions and concentration were found. The air cells’ shells are dense enough to form a cage-like structure around air cells and are equally as robust as those from hydrophobins.
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