Chemical stabilisation of oils rich in long-chain polyunsaturated fatty acids during homogenisation, microencapsulation and storage

The aim of this study was to systematically investigate the impact of chemical stabilisation on the autoxidation of microencapsulated oils rich in long-chain polyunsaturated fatty acids. During the microencapsulation process, the fish oil undergoes multiple changes of its physical properties: bulk oil, dispersed oil in aqueous phase, and dispersed oil in dry matrix. Autoxidation already occurred in the first stages of the microencapsulation process itself during emulsification and spray-drying. An efficient stabilisation was achieved using a ternary combination of lipophilic antioxidants, synergistic compounds and a trace metal chelator, e.g. a combination of tocopherols, rich in the δ-derivative and low in the α-derivative, with ascorbyl palmitate and lecithin. Trace metal chelation by, e.g. Citrem or lecithin in combination with ascorbyl palmitate proved to be of particular importance in the emulsion, but not during the storage of the microencapsulated oil. In the microencapsulated oil, the addition of rosemary extract rich in carnosic acid to ternary blends of tocopherols, ascorbyl palmitate and lecithin or Citrem significantly retarded autoxidation.