Screw press extraction of Sacha inchi seeds: Oil yield and its chemical composition and antioxidant properties

Abstract

© 2018 Wiley Periodicals, Inc. In this work, the effects of operating parameters, such as drying temperature (60, 75, 90 °C) and press head temperature (60, 75, 90 °C), on oil yields from Sacha inchi (Plukenetia volubilis L.) seeds were studied using a single screw press machine. It is found that non-dried Sacha inchi samples gave a high oil yield compared to dried samples for all press head temperatures. These Sacha inchi oils contained high content of polyunsaturated fatty acids, mainly α-linolenic and linoleic acids. The total content of phenolic compounds in these oils ranges from 30.46 to 120.32 mg GAE/100g oil, DPPH IC50value 317.33 to 663.54 mg/mL, and ABTS IC50value 215.48 to 301.75 mg/mL. Additionally, these oil samples have peroxide (1.94–2.27 meq O2/kg oil), iodine (102.66–104.05 g I2/100g oil), saponification (182.18–195.11 mg KOH/g oil) and acid (1.94–5.90 mg KOH/g oil) values, as well as the free fatty acid percentages (0.97–2.97%). Practical applications: Screw press extraction is a cost-efficient method, requiring a shorter extraction time than solvent extraction process and leaving no solvent residues in the oil product. Here, a single screw press machine at different press head temperatures was used to extract oil from Sacha inchi seeds. The various Sacha inchi oil extracts had differences in their fatty acid levels. Additionally, the Sacha inchi oil was found to contain total phenolic compounds, which can be potentially used as an alternative source of natural antioxidants in pharmaceutical or food industries.