Spirulina protein (SP) is recognized as a nutritious edible microbial protein and holds potential as a natural emulsifier. Due to the inherent challenges SP faces in stabilizing high internal phase emulsions (HIPEs), ultrasonic techniques were utilized for modification. Noticeable alterations in the structural and functional properties of SP were observed following ultrasonic treatment at various power levels (0, 100, 300, and 500 W). Ultrasound treatment disrupted non-covalent interactions within the protein polymer structure, leading to the unfolding of molecular structures and the exposure of hydrophobic groups. Importantly, the particle size of SP was reduced the most at an ultrasonic power of 300 W, and the three-phase contact angle reached its peak at 84.3°. The HIPEs stabilized by SP modified with 300 W ultrasonication have high apparent viscosity and modulus values and strong storage stability under different environmental conditions. Additionally, the encapsulation of curcumin in HIPEs led to improved retention of curcumin across various settings. The bioavailability increased to 35.36, which is 2.8 times higher than the pure oil. These findings suggest that ultrasound-modified SP is a promising emulsifier for HIPEs, and is expected to encapsulate hydrophobic nutrients such as curcumin more effectively.
Keywords: bioavailability; curcumin; high internal phase emulsion; protein structure; spirulina protein; ultrasound.