Characterization of Argentinean Chia Seed Oil Obtained by Different Processes: A Multivariate Study

Abstract

Chia (Salvia hispanica L.) seed oil is a very interesting source with regard to provide a good equilibrium between two essential fatty acids (FAs) (linoleic and α-linolenic acid). Currently, chia seed oil is not widely used commercially even though its characteristics are well-suited for industrial applications, and contribute to healthy human diets. One of the main objectives of chia oil production involves the appropriate selection of the extraction process. The yield and the quality of oil are very important to determine the feasibility of commercial production. Chia seed oil was obtained by different extraction processes, some of them commonly used by the oil industry (solid-liquid extraction and cold pressing) or by alternative technologies with supercritical CO2 (SC - CO2). The aim of this work was to analyze the oil yield, the fatty acid composition, the total tocopherol and polyphenolic compounds content and the oxidative stability of chia seed oils obtained by solvent, pressing and CO2 supercritical extraction (CO2-SE) by a multivariate statistical method. The highest oil yield was 0.34 g/g seed (d.b.) obtained by solvent extraction (hexane). It was also possible to achieve similar values by adjusting the operating conditions (pressure, temperature and time of extraction) of the SC-CO2 process. However, the oil yield reached by pressing was about 30% lower than those obtained by solvent (hexane) and SC-CO2. The fatty acid composition of oils was similar for the different processes, highlighting the α-linolenic (~65%) and linoleic (~20%) acids content and a low level of saturated acids (~9%). Furthermore, the presence of a moderate amount of bioactive compounds such as tocopherols and polyphenols, was recorded. Multivariate analysis showed that the first three principal components described about 92% of the variance. The features that differentiate the oils obtained by conventional processes from those extracted by CO2-SE were the presence of larger amounts of oleic and stearic acids, tocopherols and oxidative stability in the former, and the increased quantities of palmitic and linoleic (C18:2) acids and total polyphenol compounds in the latter.