The Application Of Natural Food-grade Colorants In Iced Foods

This report contributes to one of the ice-cream projects in Unilever Shanghai R&D Center. It aims to develop a water ice prototype which can change color during consumption, to attract more consumers and bring them pleasure and indulgence. This report focuses on the application study of anthocyanin type colorants in water ice products based on the physical and chemical properties of anthocyanin and icy products characters. Color-changing icy product prototypes are developed based on the Proof-of-Principle (PoP) study. Considering the business confidentiality, some key words will be replaced by symbols.For the color-changing by pH of water ice, our initial ideas are:1) Choose a suitable food-grade colorant which can change color by pH.2) As the pH value of ice-lolly is around3while the pH value of human saliva is around7, we hope to utilize the saliva as a neutralizer to change the pH value of the ice-lolly so as to cause the color-changing of ice-lolly.3) Reasonably design the water ice product to enable the colorant to transfer from the basic environment to acidic environment and thus result in the color-changing during the consumption.Based on the above ideas, anthocyanin type colorants are chosen as appropriate color-changing materials for use in our study. This study is progressed from a simple model system to a complex formulation, from the PoP study to the product prototype development, using pH change as color-changing trigger to make color-changing water ice come into being.In PoP studies, cabbage red is chosen as our leading material, and its color-changing under different conditions is characterized by UV-Vis spectra. Key factors on color-changing are systematically investigated which include the influence of pH range, colorant concentration, and water ice ingredients on color-changing, as well as the reversibility of the color-changing triggered by pH change. In vitro and in vivo evaluation on saliva capability to change pH value is also investigated. Product prototype is developed and corresponding in vivo tests are conducted based on the results from the PoP study.In vivo test result shows that saliva has the capability to change the pH value of the water ice, while the challenge is that the color-changing only occurs in the spitted mixture, neither on top of the tongue nor on the surface of the ice-lolly. Further attempts to make color-changing on the surface of water ice are tried after reasonable analysis of this issue, which include adopting high viscosity water ice formulation, coating layer methods etc. However, the results are still not as satisfactory as we expect. For the designed product prototype of two layers with different pH, in vivo test results show that color-changing by pH can happen on the surface of ice-lolly.