Effect of transglutaminase cross-linking and emulsification on the stability and digestion of limonene emulsions

Transglutaminase (TG) cross-linked whey proteins are used to prepare a D-limonene emulsion, which can solve the problems of easy oxidation and poor water solubility of D-limonene. TG cross-linking can improve the emulsion stability of whey protein isolate (WPI). SDSPAGE results showed that TG cross-linked WPI and limonene were emulsified under high-pressure homogenization to form the emulsion (WPI-TG-Oil), which had more molecular polymers. The adsorption rate of interfacial protein of the WPI-TG-Oil emulsion was significantly increased by 5.15 % compared to the WPI limonene emulsion cross-linked with TG (WPI-Oil-TG). After a 10-day storage interval, the CDs and POV showed that the WPI-TG-Oil emulsion had the strongest oxidation stability and a thickened interfacial layer. It was also noted that WPI-TG-Oil was difficult to hydrolyze during the digestion process due to the large degree of cross-linking and many high molecular weight polymers. The WPI-TG-Oil emulsion was more stable with a high molecular weight and improved the overall properties. Moreover, these findings provide basic theoretical and technical support for improving the stability of D-limonene emulsions. The most suitable processing method was TG-crosslinked WPI to form a stable emulsion, which improved the physiochemical and emulsifying properties of its emulsion for potential uses in food, cosmetics, and other industries.