Starch Extraction from the Green Macroalgae Ulva Sp. for Sustainable Food Systems

In light of the growing world population, Food and Agriculture Organization (FAO) of the United Nations has raised questions of sustainability of production of cereals and starch in the future. The decreasing land availability, fresh water supply, and the environmental risks associated with the expansion of agricultural lands jeopardize the sustainability of future terrestrial agriculture to supply stable, safe and secure nutrients, and particularly starch, which is main energy source in food. In addition, starch production is energy intensive: up to 42% of the energy input in starch life cycle is required for production and another 44% on processing. Another important concern with current starch supply is the pandemic problem of obesity and metabolic syndrome, which recently triggered programs for finding new sustainable starches with improved properties for human health. In this study we have isolated starch from a marine green macroalgae, Ulva sp. Pigment from dried, finely ground biomass of Ulva sp. was extracted using acetone and hot ethanol. The residue of the biomass after pigment extraction was washed with distilled water and was heated for 8 hours in presence of 0.06 M KH₂PO₄. This mixture was centrifuged to collect the supernatant. White sediments- presumably starch- from the supernatant was allowed to precipitate at 4°C which was pelleted by centrifugation and dried at 40°C. The initial yield of dry, white compound was 7% of the dry biomass. When stained with Lugol’s iodine, microscopic observation of dried white powder clearly showed presence of blue colored granules. The High Pressure Ion Chromatography analysis showed the presence of glucose after enzymatic digestion using amyloglucosidase and α-amylase. These results confirm the presence of starch in the obtained fraction. These results encourage the potential use of marine biomass to provide starch for food ingredients sustainably