Effectiveness of natural antioxidants on oxidative stability of margarines

Lipid oxidation has been identified as the main deterioration process of margarines and in which the addition of antioxidants is necessary. Consumers are increasingly demanding that natural preservatives replace chemical antioxidants in foods. The main aim of this study was to improve the oxidative stability of eight commercial margarines without antioxidants, selected by Principal Component Analysis and grouped into three clusters by the addition of six natural ground herbs: Curcuma longa, Illicium verum, Rosmarinus officinalis, Taraxacum officinale, Thymus piperella and Thymus vulgaris. A preliminary assay showed that the margarines with higher total fat and saturated fatty acids presented higher Induction Periods. When adding spices and herbs to margarines, Rosmarinus officinalis increased the oxidative stability value by 73.17% with respect to its baseline values, Curcuma longa, Thymus vulgaris and Thymus piperella between 17 and 26% and Taraxacum officinale together with Illicium verum reduced it by 19% and 34% respectively. The most effective species shown by chemical and statistical analysis were those containing a high content of highly lipophilic apolar phenolic compounds. A multiple linear regression model showed that Induction Period has a positive correlation with saturated and polyunsaturated fatty acids, omega-3 acids, the monounsaturated/polyunsaturated fatty acid ratio and the antioxidant activity of the added herbs. The oxidative stability of margarines is influenced by various factors and compounds present in their formulation, but the use of plants and spices could be an alternative to improve this emulsion.