In this work, the oxidative and thermal stabilities of 4 different encapsulating agents (chitosan [CH], modified starch [MS], gum arabic [GA], and maltodextrin [MD]) used in fennel oleoresin microencapsulation by the freeze-drying technique were evaluated both individually and in blends (binary and ternary ones). The oxidative stability of the encapsulated products was assessed by gas chromatography/mass spectrometry analysis of the secondary oxidation volatiles along with the use of oxidation markers (peroxide value, PV), while a differential scanning calorimetery analysis was conducted. Gum arabic, both plain and its mixtures, exhibited the lowest protection against lipid oxidation, presenting high PVs. However, good microencapsulation efficiency along with the best oxidative stability in terms of PV and thermal stability indicated that the formulations of MS-CH and MS-MD-CH could be suggested as alternative encapsulating agents.
Practical application: Herbal oleoresins including fennel can provide various nutritional benefits; however, they are sensitive to oxidation and should be microencapsulated. Therefore, there is a need for encapsulating agents that provide good microencapsulation efficiency and enhance at the same time oxidative and thermal stability.
Keywords: freeze-drying; microencapsulation; oxidation; stability; volatile compounds.
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