COMPARISON OF OXIDATION OF METHYL LINOLEATE ENCAPSULATED WITH GUM-ARABIC BY HOT-AIR-DRYING AND FREEZE-DRYING

Methyl linoleate was encapsulated with gum arabic by two drying method s, hot-air-drying and freeze-drying. The oxidation of methyl linoleate encapsulated by both methods depended on the relative humidity during storage. Methyl linoleate encapsulated by freeze-drying was more slow ly oxidized than that encapsulated by hot-air-drying at any relative h umidity. The initial fraction of nonencapsulated lipid in the hot-air- dried microcapsule was about 1%, and the fraction increased quickly in the early stage of storage at a high relative humidity. On the other hand, the fraction of nonencapsulated lipid in the freeze-dried microc apsule was about 10%, but it did not change during storage at any rela tive humidity. Scanning electron micrographic observation of microcaps ules prepared by hot-air-drying and freeze-drying showed that their mo rphologies were greatly different. These results suggested that the st ate of the lipid encapsulated by freeze-drying was different from that encapsulated by hot-air-drying.