Effects of microencapsulation by ionic gelation on the oxidative stability of flaxseed oil

Flaxseed oil is a major source of omega-3 polyunsaturated fatty acids (PUFAs), as it contains nearly 50% of alpha-linolenic acid. For this reason it is highly susceptible to auto-oxidation. The aim of the work was to increase the stability of flaxseed oil by a microencapsulation process based on ionic gelation through vibrating-nozzle extrusion technology, using pectin as shell material. Two different drying systems, passive air drying (AD) and fluid bed (FB), were compared. The results show that the encapsulation efficiency is very high (up to 98%). Besides being approximately 20-fold faster, FB gives beads showing on average higher payload (76% vs 68%) and lower peroxide value (9.64 vs 21.33) than the AD. An accelerated test carried out on FB-dried beads shows that the oxidative stability of encapsulated oil is 13-fold higher than bulk oil (PV FB: 20 vs PV oil: 260), demonstrating the protecting effect of microencapsulation.