Power ultrasound is one means among others of mechanically producing emulsions. In spite of numerous publications on the basic principles of this technique, there is insufficient knowledge of continuous ultrasound emulsification processes and the main parameters of practical relevance. A comparison of this system with other continuous mechanical emulsifying devices is made. The effect of continuous phase viscosity on droplet disruption due to ultrasound is the subject of a more detailed investigation. Continuous phase viscosity is varied by means of water soluble stabilizers (o/w systems) and different oils (w/o systems). At constant energy density, droplet size decreases when adding stabilizers, whereas the viscosity of the oil in w/o emulsions has no effect. Qualitative investigations of the local distribution of cavitation have shown very small penetration depths of cavitation into the liquid. This emphasizes the need for improvement of apparatus design to optimize the emulsification process.
The chemical stability of lycopene and the physical stability of lycopene emulsions diluted in 3 different food systems (skimmed milk, orange juice, and water as control) were studied. In these investigations, 3 different emulsifiers were used. It was found that lycopene stability strongly depends on the food system. In orange juice, lycopene is particularly stable. The emulsifiers used have only little influence on the stability of lycopene. Emulsions with ␣ ␣ ␣ ␣ ␣-tocopherol as an additional antioxidant showed a good lycopene stability in all food systems. Coalescence of oil droplets was not observed in any of the food systems investigated.
Lycopene can be dissolved within the oil phase of oil‐in‐water emulsions to increase bioavailability in water‐dispersible systems. It is sensitive to oxidative conditions and easily undergoes isomerization at high temperatures. Degradation kinetics and isomerization of lycopene in oil‐in‐water‐emulsions were investigated as a function of thermal treatment and oxygen content. Lycopene degradation was found to follow a first‐order kinetics and rate constants were determined. Higher temperatures are directly correlated with increasing lycopene losses. Moreover, thermal treatment leads to a significant decrease of the concentrations of all‐trans and 13‐cis isomer, while the concentration of the 9‐cis isomer increased. Oxygen‐free conditions reduce lycopene losses significantly.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.