Extraction and Concentration of Isoflavones from Soybean(Glycine max)

Abstract

The extraction and concentration of isoflavones from defatted soy flour (DSF) is attempted by leaching, membrane process and liquid-liquid extraction. The optimized extraction conditions by response surface methodology (RSM) resulted in an isoflavone content of 3.2 mg/g of DSF. The extracted isoflavones are processed by ultrafiltration for preliminary purification resulting in 3.0 mg/g of DSF, and then concentrated by liquid-liquid extraction with diethyl ether (4.8 mg/g DSF). The final isoflavone content is 69 mg/g of dried extract with an overall recovery of 57.5%. The optimization of extraction conditions resulted in an about 2.5 fold enhancement of isoflavones and concentration step enriched the isoflavones by about 8.5 fold compared to initial extract.

Optimization of isoflavones extraction from soybeans using full factorial design

“…Based on the results illustrated in Figure d, the effect of extraction time on the total extracted amounts of isoflavones was significant ( p < 0.050). The amount of isoflavones extracted increased gradually along with the increase in extraction time and achieved the maximum at 75 min, this was followed by a slight decrease, which shows similar trend to previous reports (Lakshmi et al, ; Wang et al, ). It takes a specific time for the solvent to penetrate the plant cells due to osmosis, whereby sufficient time is need for the isoflavones to diffuse from plant cells into the solvent.…”

“…The results showed that the amount of aglycone and glycoside increased gradually when the ethanol concentration was increased from 60% to 80%. However, the amount of glycoside significantly decreased with further increase of ethanol concentration from 80% to 100%, where an especially sharp drop was observed at 100% (Jankowiak et al, ; Lakshmi et al, ; Wang et al, ). The extracted amounts of aglycones were not substantially different, this difference may be explained by the solubility of both aglycones and glycosides being better in ethanol than in water.…”

“…Soy isoflavones includes genistein, daidzein, glycitein, and their respective acetyl, malonyl, and aglycone forms (Murphy, Barua, & Hauck, ; Wally et al, ; Wang, Guo, Qi, Su, & He, ). Aglycones have high bioavailability, where β‐glycosides form a large proportion of the total isoflavones content and are capable of being converted into aglycone, in which they both generate interest for extraction and application (Cho, Lee, & Park, ; Lakshmi, Rao, Ravi, & Raghavarao, ; Nemitz et al, ; Rostagno et al, ).…”

“…Among these methods, mechanical stirring extraction is the conventional process having the highest extraction efficiency due to strong mixing with heating process, ease of handling, low equipment costs as well as capable for industrial scale production. Although solvents such as acetonitrile, ethanol, methanol, and water are often used for these extraction methods, the binary mixture of ethanol and water is the best extraction solvent in terms of environment, health, and safety (Cho, Nam, & Park, ; Jankowiak, Trifunovic, Boom, & van der Goot, ; Lakshmi et al, ; Wang et al, ).…”

“…A mechanic stirring extraction not only influences various single factors such as solvent concentration, temperature, extraction time, and ratio of solvent and material, but it also creates interactions among these factors. Previous works have been carried out by optimizing three parameters such as the ethanol concentration, extraction time, and reaction temperature using response surface methodology (Cho et al, ; Lakshmi et al, ; Wang et al, ; Zhang, Ng, & Luo, ). Although the optimization of these studies focused on these major parameters, but the results carried out showed significant difference.…”