70201

SOYBEAN OIL EXTRACTION USING ETHANOL: EFFECTS OF SOLVENT HYDRATION ON YIELD, OIL COMPOSITION AND STABILITY

Favorite this paper

Alternatively to hexane, ethanol, a renewable and non-toxic solvent, can be used to extract vegetable oils from oilseeds. Studies have found that ethanol may reach the same oil-extractability as hexane, and is able to produce a more stable oil. Therefore, we aimed to evaluate the differences between two extraction processes of soybean oil: one using anhydrous ethanol (AE) and the other, 95% ethanol (HE). Extraction yield, oil content and oil stability by means of an 8-day oven test were assessed. Degummed soybean oil was used in the oven test for comparison purposes. Flaked soybean was used as feedstock. At each extraction batch (B) four cycles of immersion at 78°C, using a 2:1 solvent-to-soy ratio, were carried out. After this process, the oil/solvent mixture separates into two phases when reaching room temperature: a denser phase, rich in oil (RO) and another phase, rich in ethanol (RE). The latter was reused as solvent in the next batch. For each solvent tested, five sequential batches were performed (always reusing RE in the next batch). Results showed that AE is a much more efficient solvent than HE, with oil yields ranging from 87.5% at B1 to 72.1% at B5, whereas the latter solvent lost its extractability batch after batch, starting in 76.3% at B1 and decreasing to 51.0% at B5. The oil content of ROs obtained with AE and HE was similar and remained constant throughout batches (mean 91.4%). The oven test showed, at day 8, peroxide value of 16.0 for AE, 32.7 for HE and 74.3 meq O2/kg for degummed oil, indicating lower resistance to oxidation of the latter samples. Results show that extraction using AE can be very efficient and produced a more stable oil than its hydrated counterpart and hexane. Ethanol is a promising clean and efficient solvent for oil extraction.