Effect of moisture on the oil extraction of sunflower collets and its minor compounds content

PEREZ, E.E.; BAUMLER, E.R.; CARRIN, M.E.; CARELLI, A. A.

Concordia

Congreso; Food Innova 2014; 2014

Universidad Nacional de Entre Rios

It is well-known that the oil yield obtained during extraction depends on the moisture content of the oleaginous material; the oil yield increases as moisture decreases. However, a certain moisture level is required because it gives the collets elasticity, increases the bulk density, and hinders percolation. So far, research on the effect of moisture on oil extraction has focused on obtaining higher oil yields without considering minor compounds that affect oil quality. Some of these minor compounds have antioxidant properties (e.g., tocopherols) while others have to be removed in the refining process (e.g., phospholipids and waxes). The aim of this work was to analyze the effect of moisture content of the expanded material (?collets?) on the quality of sunflower oil by determining its wax, phospholipid and tocopherol content and composition. Low-protein sunflower collets were conditioned at three moisture levels (6, 12 and 18% dried basis, d.b.) prior to oil extraction. Oil extraction was carried out at 50 ºC for 2 h in a magnetically-stirred batch reactor using n-hexane as solvent. The amount of oil extracted was determined gravimetrically. Tocopherol content was measured with an HPLC instrument equipped with a fluorescence detector using AOCS method. Quantitative determination of phospholipids was carried out by enrichment with a diol solid-phase extraction cartridge and subsequent analysis by HPLC-UV. The wax fraction was isolated by column chromatography in a glass column with a solid stationary double phase of silica gel and silver nitrate-impregnated silica gel. Waxes were quantified by the internal standard method using a capillary GLC equipped with an oncolumn injection system and a flame ionization detector. Statistical analysis was carried out by analysis of variance (ANOVA) followed by comparisons between means with Fisher's LSD test, at 5% significance level (n=3). The increasing moisture content caused a decrement in oil yield, which was statistically different for each sample tested (p = 0.003). The total wax contents were between 896 and 1118 ppm, and they were composed mainly of esters of between 44 and 60 carbon atoms, whose distribution did not change according to the moisture content considered. In all the experiments, alfa and beta tocopherols and beta tocotrienol were detected, being the level of a-tocopherol higher than 93% and easier to extract at 12% d.b. of moisture content. Furthermore, the phospholipid content in the oil increased with moisture content, but maintaining its composition. In brief, the moisture content of the collets not only affects the oil yield, but also the content of minor compounds.