Response surface optimisation of aqueous enzymatic oil extraction from bayberry (Myrica rubra) kernels

Aqueous enzymatic extraction (AEE) of oil from Myrica rubra kernels was performed. The four AEE parameters namely mixed enzyme (cellulose/neutral protease = 1/2, w/w) amount, liquid/solid ratio, extraction time, and temperature, were optimised by response surface methodology. The statistical analysis indicated that the enzyme amount, liquid/solid ratio, time, and the quadratics of liquid/solid ratio, and enzyme amount, as well as the interactions between time and temperature, showed significant effects on oil yield. The optimal extraction conditions for oil yield were mixed enzyme amount, liquid/solid ratio, time, temperature as 3.17% (w/w), 4.91 ml/g, 4 h and 51.6 °C. Under the optimum conditions, the experimental oil extraction yield was 31.15%. The GC–MS analysis showed that the oil was abundant in the unsaturated fatty acids (9-octadecenoic acid and 9,12-octadecadienoic acid accounting for more than 80%), and the AEE was more efficient method to extract polyunsaturated fatty acid than the organic solvent process.