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A multi-series fluidic system based on the transformer concept was designed and built for the induced-electric-field-assisted extraction (IEFAE) of mulberry leaves polysaccharides (MLPs). Extraction was accelerated by exposing a secondary coil, made from a flowing mixture of sample grains and extractant, to a 20–80 kHz induced alternating electric field. The results indicate that this method benefits the release of polysaccharides without significantly affecting the quality of the products as evidenced by carbohydrate, protein, uronic acid, sulfuric radical and total polyphenol contents as well as average molecular weights and FT-IR . The polysaccharide yield improved as the excitation voltage increased, but the voltage frequency had a negative impact on the yield. At a solid-liquid ratio of 1:20 (g/mL), pH of 2.5, 60 °C temperature, 1000 V excitation voltage, and 20 kHz frequency, the 16-series system is performed optimally with a yield increased by 225.95% compared to the control (0 V). The relatively low environmental pH is conducive to extraction under the electric field, making the proposed system efficient for the extraction of valuable compounds without using metal electrode. [ABSTRACT FROM AUTHOR]

An experimental system based on the o-core transformer structure was established and used to extract pectin from orange peel waste. Unlike other electric-field-assisted techniques, it avoids the use of powered electrodes. The acidic solvent acts as the secondary coil connected to a purpose-made glass chamber which forms a closed loop. Then the induced electric field in the system appears to be under the influence of alternating magnetic flux based on Faraday's law of induction . We found that an increase in the excitation voltage causes enhancement of the pectin yield. Increasing frequency from 20 to 200 kHz had a negative impact on pectin yield partially due to the increased impedance of the primary coil. The ionic conduction was enhanced at the same excitation voltage since there are more free ions in the mixture at lower pH. This means that a lower impedance in the mixture is conducive to extraction. This multidisciplinary technique combines the transformer concept with the electric-field-assisted process, thus providing a reference for the application into agricultural by-products treatment. [ABSTRACT FROM AUTHOR]