Effect of monoglyceride self-assembled structure on emulsion properties and subsequent flavor release

Abstract

When monoglyceride (MG) was dispersed in oil above melting point, it formed self-assembled structures (liquid crystals) on cooling, which have the potential to structure oil in emulsion systems. In this study, the effects of MG on emulsion properties and subsequent flavor release were investigated. Model oil-in-water (O/W) emulsions stabilized with tween 20 (1% w/w, TW) and whey protein isolate (1% w/w, WPI) were prepared using microfluidization. All emulsions, with droplet size ranging from 170nm to 387nm, showed good stability during storage. In TW emulsions, DSC results indicated that development of MG crystalline structure occurred within 3days of storage. The MG self-assembled structures largely modified the rheological behaviors of the emulsions, which showed an increased storage modulus on storage and the TW emulsion gave gel property (G′>G″). The crystallinity was highly dependent on the content of MG in the system, while independent on the content of oil. However, the gel property was affected by the content of oil and MG. For WPI emulsions, very little MG crystallized during storage, and the WPI emulsions remained Newtonian. When limonene was introduced into the oil phase of these emulsions, a delay in the release of limonene in MG structured emulsions was observed by headspace analysis. Changes in emulsifier types and oil contents greatly influenced limonene release. The results of this study demonstrated the potential of using MG structured emulsion for controlled release of flavors, possibly in fat-reduced system.