Global population increase and the depletion of agricultural land and shortage of freshwater, make ocean aquaculture an attractive alternative source for food. Macroalgae contain a wide variety of nutrients such as protein and starch. Algae can contain up to ~50% protein and up to ~30% starch, by dry weight. These biopolymers are a source of energy and building blocks for the human body and have various functional properties useful in food processing.
Herein, we used the green macroalgae Ulva as a model, and developed a food grade protein extraction protocol, which yielded an algae protein concentrate (APC) containing >70% protein. We found that the concentrate contains all the amino acids, including the essential ones, and that 90% of the protein undergoes proteolysis under simulated digestion. The concentrate exhibited high antioxidant activity due to the presence of polyphenols co-extracted with the proteins. We currently use the protein extract to develop fish alternatives.
Starch extracted from ulva contained a high amount of amylose relative to starches from terrestrial sources such as rice and potatoes. The algal starch had a higher retrogradation tendency, due to the high amylose content, which led to better gelling properties and high resistance to enzymatic digestion, which is desirable, as it causes a moderate glycemic response.
These results indicate there are functional, health and environmental benefits to using macroalgae as a new and sustainable source of protein and starch for human diet and the food industry.