Study on the preparation and characterizations of whey protein-sweet orange oil inclusion complex

The preparation process of whey protein-sweet orange oil inclusion complex using high pressure homogenization was optimised by orthogonal experiments. The basic characteristics of inclusion complex were studied to provide technical support for developing and applying the inclusion complex. The results showed that the optimal conditions to prepare the inclusion complex were as follows: homogenization at 40 MPa for 3 times, the ratio of the amount of whey protein to the volume of sweet orange oil was 1∶0.75(g∶mL). Under this condition, the inclusion rate of sweet orange oil could reach to 84.11%, and the effective content of sweet orange oil in the complex was 346.36 mg/g. Gas chromatography-mass spectrometry(GC-MS) detection suggested that the characteristic flavors of sweet orange oil, such as aspinene, myrcene, limonene, and decanal were well preserved in the inclusion complex. The particle size of the inclusion complex was evenly distributed, in a range of 100-600 nm. In addition, its superficial area weighted mean diameter and volume weighted mean diameter were(180±8) nm and(333±5) nm, respectively, which suggested that the inclusion complex was suitable for beverage industries. The moisture content and water activity of inclusion complex were(4.59±0.46)% and 0.211±0.037, respectively, which was beneficial for storage. However, the inclusion complex was easy to absorb moisture, it should be stored in the environment with relative humidity below 43%. The retention rate of sweet orange oil in the inclusion complex was 93.74% after being sealed in bags and stored at 25 ℃ for 10 weeks, it meant that the inclusion complex could protect the sweet orange oil well.