Headspace GC/MS for identification of bioactive compounds of Curcuma longa L. leaf extract: Industrial application as antioxidant for soybean oil

ABSTRACT The use of natural antioxidants extracted from plants is an alternative to the application of synthetic antioxidants. In this study, we evaluated the oxidative stability of soybean oil after the addition of Curcuma longa L. leaf extracts compared to its oxidative stability with the synthetic antioxidant butylated hydroxytoluene (BHT Different concentrations (0.5%, 1.0%, and 1.5%) of ethanolic extract of Curcuma longa L. leaves were added to the oil, and the mixture was heated at 60 ±2 °C for 12 days. Several parameters of oxidative stability, including the peroxide index (PI), thiobarbituric acid reactive substances (TBARS), and conjugated dienes and trienes, were analyzed every three days. The results were promising, the oils to which the Curcuma longa L. leaf extract was added showed a reduction in all parameters, indicating oxidative deterioration under the influence of the concentration of the extract and the duration of treatment. The extract was less effective at low concentrations (0.5%), the parameters did not vary considerably. The PI was low in all treatments until the third day. The PI of the soybean oil treated with 1.5% extract was lower than that after treatment with the synthetic antioxidant and the blank treatment on days 6 to 12. The highest production of TBARS was observed in the blank treatment on days 6 to 12, and the lowest values of TBARS were recorded in the soybean oil treated with 1.5% extract. For the same concentration, the conjugated dienes varied from 2.05 to 8.6, and the trienes from 0.57 to 1.59.