Optimization of microwave-assisted extraction of oil from tiger nut (Cyperus esculentus L.) and its quality evaluation

In this study, Microwave-assisted extraction (MAE) was firstly applied in extraction of tiger nut oil (TNO). Parameters of MAE were optimized by response surface methodology. The optimum extraction conditions were a mixture of petroleum ether (boiling range 60-90 degrees C) and acetone (2:1, v/v), microwave power 420 W, temperature 75 degrees C, liquid to solid ratio 7.0 mL/g and time 55 min, which could obtain yield of 24.12%. The fatty acid composition of oil by MAE was similar to that of oil by Soxhlet extraction (SE), whereas oil by MAE exhibited superior physicochemical properties and oxidation stability. Moreover, oil by MAE had a higher content of total phenolic, alpha-tocopherol, beta-carotene, phospholipids and phytosterols. Scanning electron microscopy demonstrated that structural disruption of tiger nut caused by microwave irradiation was the main reason for rapid extraction. So MAE could be a good alternative for extraction of TNO.