Search

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]

Pumpkin polysaccharides are considered as functional materials with bioactivities. However, the conventional aqueous extraction method for pumpkin polysaccharides is limited by long time consumption, low efficiency and potential damage to their bioactivities. To improve the efficiency of pumpkin polysaccharides extraction, we designed a new experimental system combining a rotary magnetic field and flowing conductive solution. Polysaccharide extractions by 1) acidic sample solution with agitation, 2) flowing acidic sample solution, 3) static magnetic field combined with flowing acidic sample solution, and 4) rotary magnetic field combined with flowing acidic sample solution were conducted at pH level of 2–4, temperature of 30–50 °C, and treatment time of 0–180 min. The extraction by use of rotary magnetic field combined with flowing acidic sample solution resulted in the highest polysaccharide yield. Then, the effects of rotational frequency, Reynolds number, pH, and temperature on extraction yield were investigated. The yield increased at first and then decreased with an increase in rotational frequency. The high polysaccharide yield was achieved at large Reynolds number, high temperature, and low pH. From the ultraviolet, Fourier transform-infrared spectrum and chromatographic analysis, the extracts proved to be polysaccharides with an average molecular weight of 1.435 × 10 5 Da. The extracted pumpkin polysaccharides exhibited a dose-dependent radical-scavenging capacity within 0.1 to 5 mg/mL in the order of hydroxyl radical > DPPH radical > superoxide radical. Industrial relevance Rare report on the application of the combined magnetic field and pipe-fluid technique in extraction functional components from food materials. In this study, a novel experimental apparatus combining rotary magnetic field and spiral-pipe flow was designed to accelerate the extraction of pumpkin polysaccharides. In comparison with 1) agitation, 2) flowing acidic sample solution, and 3) static magnetic field combined with flowing acidic sample solution, the method combining rotating magnetic field and flowing acidic sample solution 4) significantly increased the polysaccharide yield. The increments were 40.18%, 32.14%, and 23.32%, respectively, after 180-min extraction. The pumpkin polysaccharides extracted by this novel method possessed a molecular weight of 1.435 × 10 5 Da and showed desirable antioxidant activities in vitro. Therefore, the combined magnetic field and pipe-fluid technique it is a potential method for efficient extraction of valuable compounds from food materials. [ABSTRACT FROM AUTHOR]

Pretreatment technologies make pressed fruit peel more valuable both nutritionally and economically. Robust electrofluidic systems, in particular, can facilitate clean and efficient production of valuable compounds from these byproducts. In this study, a multi-series system was designed with a combination of pipeline flow and induced electric field (IEF), then applied to pretreat citrus peel for enhancing the extraction of essential oils. The essential oil yield increased significantly from 0 V to 1 kV. There was a decrease in fluid impedance during the IEF-pretreatment period owing to the dissolution of cell contents, as well as a slight decrease in essential oil yield as frequency increased. Forty components were identified in the essential oils representing over 97% of the total GC peak areas for both procedures. We also observed significant effect on the essential oil yield between the IEF-pretreatments in different winding direction of the sample coils. High throughput was achieved by arbitrarily increasing the reactors within a compact system. In effect, the IEF-pretreatment is an effective, innovative, and ecologically sustainable technique for intensifying essential oil extraction without necessitating metal electrodes, thus avoids electrode surface corrosion, and heavy metal contamination. [ABSTRACT FROM AUTHOR]