Microencapsulation of red palm oil and its stability during accelerated storage

Introduction : Sensitivity of red palm oil (RPO) towards oxidation is known to result in degradation of nutritional value and organoleptic properties. This study aimed to determine the stability of microencapsulated RPO during accelerated storage at 65˚C for 24 days. Methods : Microencapsulated was undertaken by co-extrusion technology using sodium alginate with high methoxyl pectin, and calcium chloride solution enhanced with chitosan as cross-linking agent in the presence of Tween® 80 as surfactant. The encapsulated beads were freeze dried and the physical properties, antioxidant activities and total carotenoid content of dried powder were determined. Microencapsulated red palm oil (MRPO) was then subjected to accelerated storage at 65°C for 24 days. Results : Antioxidant activity of both RPO and MRPO measured by DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity was significantly decreased, with higher percentage loss in MRPO during accelerated storage. RPO and MRPO also experienced decreases in percentage inhibition with higher percentage of loss as measured by Azino-bis (3 ethylbenzothiazoline-6-sulpohnic acid) (ABTS) radical scavenging activity. Both RPO and MRPO showed decreasing trends in total carotenoid content, with higher content in MRPO than RPO at end of storage period. Antioxidant activities of RPO and MRPO correlated well with the carotenoid content, with best correlation coefficient in RPO between the ABTS assay and total carotenoid content measured by high performance liquid chromatography (r=0.952). Very strong association between DPPH and ABTS values (r=0.871) for the MRPO, and between DPPH and total carotenoid content (r=0.856) were noted. Conclusion : The study showed that microencapsulation effectively protected the carotenoid content in MRPO, but not its other natural antioxidants.