Optimizing Solvent Extraction of Boronia megastigma (Nees) Flowers

Various factors which influence solvent extraction efficiency of boronia flowers were examined. Factors included the duration and temperature of extraction, the volume of solvent and the number of washes used, the degree to which floral tissues were in contact with the solvent, and the sample size extracted. Extract yield (% of fresh flower weight) can be increased by 90% by rolling (squashing) frozen flowers prior to extraction. With this process the extraction of volatile compounds increased by 48%, particularly β-ionone which increases by 23% per gram of flower material extracted. The extraction of ethanol-soluble compounds is also improved by rolling the flowers, with 127% increases in yield of absolute per gram of flowers. Saturation of the solvent by extract components is not a limiting factor during extraction. Selective extraction of β-ionone occurs when low volumes of solvent are used (4 L of solvent per kg of flowers), producing extracts with enhanced organoleptic qualities. Increased extraction time during the first two of three or four washes increases the yield of extract. Longer extraction times for the whole extraction enhance the content of volatiles within, and the organoleptic qualities of the extract. Increasing the temperature from 4°-12°C increases the yield of volatile compounds and extract; above 12°C the yield of extract increases but the yield of volatile compounds declines. As a result of this research, precise recommendations can be made for extraction. In addition, different products can be produced by rolling flowers or using reduced solvent volumes. © 1998 Allured Publishing Corp.