Glucoraphanin extraction from Cardaria draba: Part 1. Optimization of batch extraction



Glucosinolates have historically been considered an anti-nutritional component of food and feed cereal crops. Large-scale protocols have been aimed at complete glucosinolate elimination from plants, rather than maximizing the recovery of any particular glucosinolate compound. Recently, glucoraphanin, an alkenyl glucosinolate, has been found to have nutritional value in terms of anti-carcinogenic behavior and hypertension relief. In this work, we report on the efficient capture of glucoraphanin from the noxious weed Cardaria draba. The effect of temperature, ethanol content in the aqueous solvent, initial solvent pH, solids loading, and contact time on both glucoraphanin and glucosinalbin recovery were examined. The optimal extraction conditions, evaluated using 0.11 dm3 stirred baffled vessels, were found to be 20% aqueous ethanol solvent at 70 °C and an initial pH value of 3, extracted at a solid to liquid ratio of 50 g dm−3 over 20 mins. The recovery achieved with the baffled vessels was up to three times greater than the glucoraphanin yield obtained using standard analytical procedures that involved the use of 8.0 × 10−3 dm3 of hot, 80% ethanol solutions in test tubes at the same solvent loading. This corresponds to 30 mg g−1 of glucoraphanin recovered from the dried C draba leaves, versus only 10 mg g−1 using the analytical method. Copyright © 2005 Society of Chemical Industry