Antioxidation effect of alginate beads containing thyme, rosemary or geranium essential oils in lard and coconut oil

Abstract

The alginate beads encapsulated thyme (AT), rosemary (AR) and geranium (AG) essential oils (EOs) were prepared to inhibit lipid oxidation in lard and coconut oil. The result showed that beads dried in hot air oven (45 °C) encapsulated higher amount of EOs than drying by desiccation method. Sachets containing AT, AR and AG were applied in PET bottles containing lard and coconut oils and stored at 45 °C. The DPPH scavenging activities of AT, AR and AG were 85.39%, 78.26%, and 78.12%, respectively. During storage, released EOs reduced PV and TBARS of lard and coconut oil and did not affect their colour acceptability scores. From PV, FFA and TBARS, AT at 0.50 g exhibited the best results in terms of lipid oxidation inhibition, although encapsulation percentage and release were significantly lower than AG and AR. Porous in alginate beads could entrap lipid oxidation products, including volatile compounds and water vapour. Besides, the hydrophilic property of polymer matrix led to water absorption, which lower aw value. In week3, the odour acceptability scores of control lard failed, while those packed with AT, AR and AG were acceptable. Alginate beads containing EOs can be used to extend the storage life of lard and coconut oil.