Properties of caraway (Carum carvi L.) essential oil encapsulated into milk protein-based matrices

Encapsulating properties of whey protein concentrate (WPC), skimmed milk powder (SMP), and their mixtures with maltodextrins (MD) for encapsulation of caraway essential oil by spray drying were studied. Encapsulation efficiency (EE) was higher in WPC-based matrices compared to SMP. Partial replacement of WPC by various MD increased the retention of volatiles during spray drying and enhanced protective properties of solidified capsules against oxidation and release of volatiles during storage. The opposite tendency was shown by SMP matrices: adding MD to the wall composition resulted in lower retention of volatiles during drying and lower oxidation stability compared to the SMP and all WPC based matrices. Dynamic headspace analysis (DHS) was applied to determine the rate of release of volatiles from the microencapsulated powders. Results revealed that combined matrices of SMP and carbohydrates had the highest volatile release ratio. Partial replacement of WPC by MD significantly reduced release of volatiles from capsules as determined by DHS. Flavor profile of caraway oil entrapped in the matrix was similar to that of pure essential oil: a small decrease in limonene content was recorded for some matrices. The results of scanning electron microscopy (SEM) of microencapsulated particles showed WPC-based matrices to have less visible cracks and holes compared to SMP. More dented surfaces could be observed in particles containing MD as compared to WPC only. It was concluded that WPC-based matrices were more effective as caraway oil encapsulating agents as compared to those of SMP. The incorporation of carbohydrates to WPC results in obtaining more effective microencapsulants.