Optimization of Microwave-Assisted Ethanol Extraction of Brown Pigment from Longan Seeds by Response Surface Methodology

摘要

Longan (Dimocarpus longan Lour.) seeds are waste materials during the processing of longan fruits. In order to make use of these waste materials, the brown pigment was extracted. A microwave-assisted extraction technology was studied and the extracting parameters were optimized by Response Surface Methodology (RSM). The effects of the parameters such as the extraction time, temperature and concentration of solvent on the yield of brown pigment were investigated. The optimal extraction conditions were 55% (v/v) ethanol, solid to liquid ratio of 1:20, 50℃, and 42 min. Under these conditions, the yield was 23.1%, which was higher than water bath ethanol extraction method and ultrasonic assisted water bath extraction method. The method is also fast, energy efficient and environmental friendly and thus could be applied in the longan processing industry in the future.