Assessment of curcumin self-emulsion containing high methoxyl pectin-whey protein complex: Quality stability by thermal, freeze-thaw treatment, and release characteristics

Abstract

Polysaccharide-protein complexes have been commonly used in recent years to improve the quality and stability of emulsions. In this study, we evaluated the effect of high methoxyl pectin-whey protein complex (HWC) on the storage stability and in vitro release characteristics of curcumin self-emulsion systems. The droplet size and loading of the curcumin self-emulsion system were approximately 306.60–353.45 nm and 2.21 mg/mL, respectively, with good dispersibility. The thermal stability of HWC was significantly increased (p < 0.05) by the formation of amide groups at pH 5, as confirmed by Fourier transform infrared spectroscopy. After three rounds of freeze-thaw cycles, the stability and retention rate of curcumin approached 92.98 and 97.83%, respectively (p < 0.05). The retention rate increased from 43.81 to 51.76% during a 20-day storage test in a light environment by adding whey protein to improve photostability. In the in vitro gastrointestinal test, the release rate in simulated gastric fluid decreased from 67.71 to 47.50% in 60 min and increased from 62.22 to 73.17% in simulated intestinal fluid in 90 min. Thus, emulsification technology can be used to improve the quality and stability of curcumin processing and can be applied to health food development.