A complete evaluation of thermal and oxidative stability of chia oil

Chia (Salvia hispanica L.) seed oil is the richest natural source of [alpha]-linolenic acid, an n - 3 polyunsaturated fatty acid ([omega]-3 PUFA), contributing to its use as functional and nutraceutical food in large part of Latin America. However, a food with such fatty acid composition could be highly susceptible to lipid oxidation. Thus, the present study was conducted to determine the thermal and oxidative stability of chia oil by various methods. Rancimat method was used to evaluate the effect of synthetic and natural antioxidants in the oxidative stability. Pressurized differential scanning calorimetry (PDSC), Schaal test and .sup.1H NMR spectroscopy were used to assess the thermal stability. The effect of frying temperature and/or heating time on fatty acid composition was assessed by .sup.1H NMR. The results show that tert-butylhydroquinone (TBHQ) and a mixture of TBHQ and rosemary extract were effective in increasing the oxidative stability of chia oil. Concerning the storage conditions, PDSC, Schaal test and .sup.1H NMR data showed that chia oil is stable at 60 °C; hence, there is no need for special storage conditions. PDSC and .sup.1H NMR results indicate that chia oil cannot be used in cooking and frying, because at high temperatures severe degradation of the unsaturated groups and loss of the nutritional properties of the oil occur.