Effect of Sunflower Collets Moisture on Extraction Yield and Oil Quality

Abstract

The aim of this work is to analyze the effect of moisture content of sunflower expanded material on the quality of the extracted oil by determining its wax, phospholipids, and tocopherol content and composition. Sunflower oil extraction is carried out in a batch extractor at 50 °C using hexane and three moisture levels (5.65, 12.40, and 18.92% dry basis). The increasing moisture content causes an increment in both oil yield and total amount of minor compounds. The total wax content ranges between 808 and 1118 ppm, the wax fraction is composed mainly of esters of between 44 and 58 carbon atoms (>67%), and the distribution does not change with the moisture content. In all the experiments, α‐ and β‐tocopherols and β‐tocotrienol are detected, with the level of α‐tocopherol being higher than 93% and easier to extract at 12.40% moisture. Furthermore, the phospholipids content in the oil increases with moisture content but maintains its profile composition. The obtained results can be explained in terms of water activity and the effect of moisture and hexane extraction on solid structure, studied by scanning electron microscopy. In brief, the moisture content of the collets not only affects the oil yield but also the content of minor compounds, the intermediate moisture rendering the better oil yield and quality. Practical Applications: The data obtained provides updated information on oil yield and quality associated with moisture content of sunflower collets, useful to select the optimal operating conditions for oil extraction and to establish a trade‐off between performance and quality. Sunflower collets are conditioned in their moisture content to determine the isotherm sorption and the effects on the oil extraction and quality.

Performance of Green Solvents in the Extraction of Sunflower Oil from Enzyme‐Treated Collets

“…The obtained values were within the range reported for these raw materials in Argentina. [ 8,27,28 ]…”

“…similar yields to those found in the present work, and slightly higher at 5.65% d.b. [ 28 ] Figure 3 shows that this effect increases significantly at higher moisture contents (>25%).…”

“…The obtained values were within the range reported for these raw materials in Argentina. [8,27,28] The oil and protein content of the pretreated collets was also quantified, with values of 19.74 ± 0.19% (d.b.) and 38.70 ± 0.60% (d.b.…”

“…The water sorption isotherm of sunflower meals and collets can be divided into three regions. [28,30] At low moisture, in the monolayer region, water is strongly retained by hydrophilic bonds on the polar sites in the solid matrix (mainly carbohydrates and proteins), so it practically does not interact with the solvent. Monolayer values have been reported in the 4-5.7% d.b.…”

“…range for sunflower meals and collets. [28,30] In the intermediate region, water is retained mainly by adsorption in multilayers with weaker bonds in the microcapillaries and the fibrous structure of the solid. Adsorbed water produces the expansion and disruption of the structure, enabling the adsorption and diffusion of the solvent.…”