Production of an Isoflavone Concentrate from Red Clover Flowers

Abstract

Red clover flowers are a rich source of isoflavones in the forms of biochanin A, formononetin, genistein, and genistin. A simple process was developed to recover isoflavones from red clover flowers as a nutraceutical product. Isoflavones were 1st extracted in alkaline water and insoluble polyvinylpolypyrrolidone (PVP) was then added to the extract for adsorbing isoflavones. The adsorbed isoflavones were subsequently eluted with ethanol and dried. The main steps of this process were optimized for the product yield and quality. The final product was an isoflavone concentrate, containing more than 20 wt% isoflavones, which represented a recovery of greater than 50% of the total isoflavone amount in red clover flowers.

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

“…The extraction curves in Fig. 1 indicate that similar to alkaline extraction (Xu et al, 2005), ethanolic extraction of isoflavones also took about 2 h to reach equilibrium in the cases of 30%, 40% and 50% ethanol concentration (v/v) in water, where the isoflavone concentration in the extract increased steadily in the first 2 h and then began to level off. Fig.…”

“…The results of isoflavone analyses for this batch of red clover flowers were reported in the work of Xu et al (2005), including a total isoflavone content of 2590 μg/g, of which biochanin A and formononetin were the major components. The findings were similar to those reported by some previous researchers (Chen et al, 2004;Liu et al, 2001;Vetter, 1995).…”

“…All ethanol samples were analyzed as is, and solid samples were analyzed as reported earlier (Xu et al, 2005). For the determination of isoflavone concentration, a HPLC-based method was used according to the parameters set by Klump et al (2001).…”

“…The isoflavone composition of red clover, however, is quite different from that of soybeans. The predominant components in red clover are biochanin A and formononetin (Chen, Jin, Tao, & Qin, 2004;Liu et al, 2001;Xu, Lamb, Layton, & Kumar, 2005), which are methyl ether derivatives of genistein and daidzein, respectively, whereas in soybeans genistin and daidzin, the respective glucosides of genistein and daidzein, are the principal isoflavones. However the glucosides of these, sissotrin and ononin, were not detected.…”

“…More economical and efficient processes have yet to be developed which are suitable for the recovery of isoflavones from red clover. Xu et al (2005) described a simple scheme to recover isoflavones from red clover flowers as a concentrate, consisting of four main steps: extraction, adsorption, elution and drying. This process was able to produce a final product with an isoflavone content of approximately 20%, which accounted for more than half of the total amount of isoflavones in red clover flowers.…”