Recovery of isoflavones from red clover flowers by a membrane-based process

Abstract

Isoflavones in red clover flowers were extracted and recovered using a new process that mainly comprised of ethanol extraction, membrane processing, micelle formation and drying. To obtain maximum isoflavone extraction an ethanol concentration between 40% and 50% in water was found to be optimal. The extracted isoflavones were processed by ultrafiltration for preliminary purification, and then concentrated by reverse osmosis. As ethanol was removed by evaporation, micelles were formed in the reverse osmosis retentate, which was dried to yield an isoflavoneenriched product. This product contained about 9% isoflavone highlighting its potential use as a direct nutraceutical supplement. Crown Copyright © 2006 Published by Elsevier Ltd. All rights reserved. Keywords: Isoflavones; Red clover flower; Extraction; Membrane and processIndustrial relevance: Isoflavones present in agricultural biomass are utilized as source of functional food supplements. Extraction and refining of isoflavones involves several steps and the process is very energy intensive. This work reports an interesting approach for extraction and refining of isoflavones by developing a new process, which is energy efficient and gives a final product, which contains sufficiently high amounts of isoflavones for consumer applications.

Simulation, scale-up and economics of adsorption and membrane based processes for isoflavones recovery

“…The equipment occupancy together with recipe scheduling was regulated for a standard eight hours batch. The supplementary input streams were adjusted accordingly so that the concentration and distribution of individual components across the streams matches and the model verifies with the reported laboratory scale process (Xu et al, 2005(Xu et al, , 2006. In all cases, the entire simulation was set in a design mode, where the program determined the size of equipment based on input streams and would select more than one piece of equipment based on the physical limitations.…”

“…3 was modeled as a batch recipe using literature data (Xu et al, 2006). Each batch was mixed with an ethanol solution at solvent-toflower ratio of 40:1 at ambient conditions in a reactor vessel unit procedure (R-101), which was integrated with charge and agitation unit operations.…”

“…The ethanol solution from MX-103 was then cooled at room temperature in a cooling step (HX-103). The ethanol solution was then recycled to an elution step (R-101) through custom mixing unit procedures (MX-104 and MX-105) in order to adjust ethanol concentration at 50% (v/v) as described in the literature (Xu et al, 2006). The custom mixing procedures MX-104 and MX-105 were individually compensated for the water and ethanol that has been lost in previous procedures respectively.…”

“…Isoflavones recovered from red clover flowers by utilizing the same methods developed for soybeans often require large quantity of organic solvents in conjunction with various chromatographic techniques, which entails longer processing time and are not cost effective (Chang, 2002). More efficient and economical processes based on adsorption and membraneseparation were discussed in earlier studies, where the product could be directly used as isoflavone supplements or further purified to obtain isoflavone isolates (Xu et al, 2005(Xu et al, , 2006). An adsorption based approach reported by Xu et al (2005) comprises four major steps: extraction, adsorption, elution and drying in order to recover isoflavones.…”

“…The technique was developed to produce a final product with isoflavones content of approximately 20% that was accounted for more than 50% of the total isoflavones in red clover flowers. A more straight forward membrane based approach was reported for isoflavones processing from the red clover flowers (Xu et al, 2006). The resulting product in membrane based process had 9% isoflavones, which represented about 35% of the total isoflavones content in red clover flowers and may be used as an isoflavones supplement without further processing.…”