Investigation of properties of sunflower and rapeseed oils obtained by the soxhlet and microwave extraction methods

The main purpose of the study was to evaluate the possibility of replacing hexane, which is traditionally used for the extraction of vegetable oils, with ethanol as a safer solvent when extracting oil from sunflower meals and rapeseed in the microwave field. Thus, the influence of the solvent type on physicochemical characteristics of oil and the low-fat meal was studied. The main indicators of the composition and quality of sunflower and rapeseed extraction oil were studied. The quality of oil and ways of its use in food products are mostly determined by its fatty acid composition. Analysis of the fatty acid composition of the oil was performed by the method of gas chromatography using a column HP-88 100 m* 0.25 mm*0.20 µm. The possibility of using oil in food was established by conducting pilot laboratory studies and investigating changes in physicochemical parameters during storage. The extraction by the Soxhlet method (hexane as a solvent) was compared with the method of extraction of raw materials in a microwave field (ethyl alcohol as a solvent). Studies of physicochemical parameters indicate the degree of oil oxidation (determi¬nation of peroxide and anisidine values). The peroxide value is an indicator of the content of primary oxidation products. The peroxide value of the oil obtained by the method of Soxhlet extraction (hexane as a solvent) was 5.0 (½O mmol) kg–1. The peroxide value of the oil obtained by extraction in a microwave field (ethyl alcohol as a solvent) was 3.8 (½O mmol) kg–1. The anisidine value is an indicator of the content of aldehydes in vegetable oils (secondary oxidation products). The anisidine value of the oil obtained by the method of Soxhlet extraction (hexane as a solvent) was 0.3 s.u. The anisidine value of oil obtained by extraction in a microwave field (ethyl alcohol as a solvent) was 0.2 s.u. Comparing the data of peroxide and anisidine values, it can be argued that the oil obtained by extraction of raw materials in a microwave field (ethyl alcohol as a solvent) had the best indicators. The acid value is one of the main qualitative indicators that characterize the degree of oil freshness. The acid value of the oil obtained by the method of Soxhlet extraction (hexane as a solvent) was 3.1 (mg KOH) g–1. The acid number of the oil obtained by extraction in a microwave field (ethyl alcohol as a solvent) was 2.1 (mg KOH) g–1. A comparison of the acid values of oils extracted from the raw material by different extraction methods shows that the oil obtained by the method of extraction of raw materials in a microwave field using ethyl alcohol as a solvent has the best acid value. Studies have shown that the oil, which was obtained by extraction of raw materials in a microwave field using ethyl alcohol as a solvent, had the best resistance to oxidation during storage (three months).