Abstract:To improve the stability and bioavailability of β-carotene and make full use of the nutritional and functional advantages of double proteins，this study mixed tilapia protein isolate （TPI）and whey protein isolate（WPI）as the emulsifier，and prepared the composite protein emulsion loaded with β -carotene through high pressure homogenization and heat treatment，thus exploring the effects of the mass ratio（2∶1，1∶1，and 1∶2）of the two kinds of proteins on the stability，antioxidant activity，and in vitro digestion characteristics of the emulsion.The results showed that，the stability of the TPI-WPI composite emulsion and the bioavailability of the loaded β-carotene were significantly improved as compared with single TPI or WPI emulsion.When the mass ratio of TPI and WPI was 1∶2，the initial particle size of TPI-WPI composite emulsion was 259.18 nm，and the absolute value of zeta potential was 28.23 mV.In addition，the composite emulsion had good stability，and there was no delamination after storage for 21 d at 4 ℃.When the mass ratio of TPI and WPI was 2∶1，the retention rate of βcarotene in composite emulsion was 62.36% after storage for 21 d，and DPPH free radical and ABTS+free radical scavenging rates were 54.83% and 40.11%.After in vitro digestion，the bioavailability of β -carotene was 24.76% with the high release rate of free fatty acids in the emulsion.Therefore，the addition of WPI enhanced the stability of the composite emulsion，and the addition of TPI increased the stability and bioavailability of β -carotene in the emulsion.The findings of this study provided a basis for the construction of stable emulsion system and the delivery of active ingredients for mixed proteins.