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Saravana, P.S.,Cho, Y.J.,Park, Y.B.,Woo, H.C.,Chun, B.S. Applied Science Publishers ; Elsevier Science Ltd 2016 Carbohydrate polymers Vol.153 No.-
Pressurized liquid extraction (PLE) was utilized to extract sulfated polysaccharides (fucoidan) from brown seaweed Saccharina japonica. Various conditions of temperature (80-200<SUP>o</SUP>C), pressure (5-100bar), and solvents (water, 0.1% sodium hydroxide, 0.1% formic acid, 70% ethanol, 50% ethanol, and 25% ethanol) were assessed; the best crude fucoidan (CF) yield was 8.23%, obtained from 140<SUP>o</SUP>C and 50bar (sodium hydroxide). Compositional analysis, FT-IR, molecular weight, monosaccharides, TGA, UV-vis, XRD, and elemental analysis confirm that extracted polysaccharides revealed the features of fucoidan. Fucose was the main monosaccharide present in CF obtained by various solvent systems. All CF showed antioxidant activities as measured by DPPH radical and ABTS<SUP>+</SUP> radical scavenging. CF demonstrates good emulsion-stabilizing capacities, especially with vegetable oils. This study demonstrates that PLE is an efficacious method for enhancing the yield of polysaccharides from S. japonica and that it could be a potential source of natural antioxidants and emulsifiers.
Hydrothermal degradation of seaweed polysaccharide: Characterization and biological activities
Saravana, Periaswamy Sivagnanam,Cho, Yong-Nam,Patil, Maheshkumar Prakash,Cho, Yeon-Jin,Kim, Gun-Do,Park, Yong Beom,Woo, Hee-Chul,Chun, Byung-Soo Elsevier 2018 Food chemistry Vol.268 No.-
<P><B>Abstract</B></P> <P>Fucoidan is a marine sulfated polysaccharide that possesses various biological activities. To enhance the functional properties of fucoidan, it was depolymerized using a green technique viz. subcritical water treatment (SCW) to produce a low molecular weight fucoidan. In this study, response surface methodology (RSM) was used to study the influence of different influences for instance temperature, pressure, liquid to solid ratio, and agitation speed to depolymerize fucoidan. RSM was used to focus on the antioxidant activity and chemical composition of SCW-treated fucoidan. Further, resulting SCW-treated fucoidan was investigated by UV-Vis, FT-IR, Thermal gravimetric analysis (TGA), DSC, Elemental analysis, and ESI-MS. Moreover, the optimized SCW-treated fucoidan was checked for cytotoxicity, antimicrobial, antidiabetic, and anticoagulant activity compared with the untreated fucoidan. The obtained values displayed that SCW treatment breakdowns polymer chain and so it produces low molecular weight fucoidan. Biological activities were improved as the molecular weight was reduced.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Fucoidan was successfully depolymerized using SCW treatment. </LI> <LI> BBD was used to find the best conditions of antioxidant and chemical composition of fucoidan. </LI> <LI> The best conditions was found to be 214 °C, 40 bar, 60 mL/g, 223 RPM and 5 min. </LI> <LI> Low molecular weight of fucoidan was obtained from SCW treatment. </LI> <LI> The optimized condition showed improved biological activities from native fucoidan. </LI> </UL> </P>
Saravana Prakash P.,R. Kalpana,Bhim Singh 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.6
A three-phase, three-switch, and three-level boost-type PWM rectifier (Vienna rectifier) is proposed as an active front-end power factor correction (PFC) rectifier for telecom loads. The proposed active front-end PFC rectifier system is modeled by the switching cycle average model. The relation between duty ratios and DC link capacitor voltages is derived in terms of the system input currents. Furthermore, the feasible switching states are identified and applied to the proposed system to reduce the switching stress and DC ripples. A detailed equivalent circuit analysis of the proposed front-end PFC rectifier is conducted, and its performance is verified through simulations in MATLAB. Simulation results are verified using an experimental setup of an active front-end PFC rectifier that was developed in the laboratory. Simulation and experimental results demonstrate the improved power quality parameters that are in accordance with the IEEE and IEC standards.
Saravana, Periaswamy Sivagnanam,Cho, Yong-Nam,Woo, Hee-Chul,Chun, Byung-Soo Elsevier 2018 JOURNAL OF CLEANER PRODUCTION Vol.198 No.-
<P><B>Abstract</B></P> <P>Herein, deep eutectic solvent combined with subcritical water extraction of seaweed polysaccharides were investigated from <I>Saccharina japonica</I>. In this regard, a deep eutectic solvent was added with sufficient amount of water and it was used as an extraction medium. To optimize, a Box–Behnken design was used to study the influences of the temperature (100 °C–150 °C), pressure (10–50 bar), water content (50%–70%), and liquid/solid (L/S) ratio (30–50 mL/g). The optimal conditions were 150 °C, 19.85 bar, and 70% water content, and L/S ratio of 36.81 mL/g showed a high yield of alginate (28.12%) and fucoidan (14.93%). FTIR, TGA, and DSC measurements confirmed that the extracted polysaccharides had the features of alginate and fucoidan. <SUP>1</SUP>H NMR data revealed that extracted alginate had an M/G ratio of 4.5 and η < 1, while monosaccharides of fucoidan had a rich content of fucose. Crude polysaccharides exhibited a moderate antioxidant activity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> SWE with DES process was employed to extract polysaccharides from brown seaweed. </LI> <LI> Box–Behnken design was used to understand the effect of process variables. </LI> <LI> The best extraction parameters were 150 °C, 19.85 bar, 70% water content and S/L ratio of 36.81 mL/g. </LI> <LI> The structural characterization of crude polysaccharide confirmed the presence of fucoidan and alginate. </LI> <LI> The obtained crude polysaccharides showed a moderate antioxidant activity. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Saravana, P.S.,Choi, J.H.,Park, Y.B.,Woo, H.C.,Chun, B.S. Elsevier B.V 2016 Algal research Vol.13 No.-
<P>In this study, Saccharina japonica was treated with pressurized hot water extraction (PHWE) at a temperature of 180 degrees C-420 degrees C and pressure between 13 bar and 520 bar. The obtained hydrolysate was investigated for their yield, total organic carbon (TOC), pH, Maillard reaction products, viscosity, color, and amino acid, mineral, and monosaccharide contents. The extraction yield increased with an increase in temperature and varied from 72.21% to 98.91%. TOC, pH, and potassium and sodium content increased, whereas viscosity decreased, with an increase in temperature. Essential amino acids such as valine and lysine and non-essential amino acids such as aspartic acid, glutamic acid, glycine, and tyrosine recovered well at low temperature. The content of heavy metals such as arsenic, cadmium, mercury, and lead was very low in the obtained hydrolysate. The maximum amount of total amino acids was recovered at 180 degrees C/13 bar (761.95 +/- 14.54 mg/g). The level of main monosaccharides such as glucose (6.70 g/L), fructose (8.40 g/L), and mannitol (17.50 g/L) was found to be very high at 180 degrees C/13 bar. The results indicated that the pressurized hot water extract of S. japonica has good potential for use in the fermentation industry and can be used as human food. (C) 2015 Elsevier B.V. All rights reserved.</P>