High-Voltage Pulsed Electric Field Preprocessing Enhances Extraction of Starch, Proteins, and Ash from Marine Macroalgae Ulva ohnoi

Marine macroalgae are an attractive source for biorefineries as an alternative to terrestrial crops, and new, sustainable macroalgae biomass fractionation methods are needed. One of the least investigated macroalgae-derived products is starch. In this work, we report on a device and a protocol for pretreatment for starch extraction from a green macroalga Ulva ohnoi (U. ohnoi) with an emerging, nonthermal, and environmental friendly technology - pulsed electric field (PEF). Using the custom-made insulated gate bipolar transistor-pulsed generator combined with a gravitation press-electrode device, we show that 200 pulses with a field strength of 1 kV cm^-1, pulse duration of 50 μs, and pulse repetition rate of 3 Hz concentrate the starch in the U. ohnoi biomass by 59.38% by removing the salts, proteins, and other small molecules. The starch extraction yield from the PEF-pretreated biomass is 59.54 ± 1.34%, compared to 52.31 ± 3.21% from untreated biomass. In addition, PEF combined with pressing increased the coextracted macroalgae protein by more than 4 times and ash by 1.5 times in comparison with pressing alone. These results indicate the potential of PEF pretreatment for challenging macroalgae biomass fractionation in the sustainable marine biorefinery.