Characterization of biopolymeric compounds extracted from macroalgae

World population is expected to reach ~9.6·10⁹ by 2050. Consequently, there is growth in demand for food, which requires seeking new sources and new ways to increase food production. These facts together with decreasing agricultural land and dwindling fresh water resources make the oceans an attractive alternative domain for basing cultivation practices for human benefits.

Macroalgae consist of a wide range of nutrients, many of which have significant importance in human nutrition and great economic potential for the food industry.

Ulva sp. is good candidate since it is rich in proteins (7-24% of alga`s dry matter), contains up to 30% (of d.m.) starch and up to 40% of other polysaccharides. Along with those major fractions, the alga contains sub fractions such as minerals, fats and phytochemicals.

After successfully extracting and characterizing algal proteins, our work currently focuses on the characterization of algal starch, in terms of rheology and digestibility. In our preliminary results, starch extracted from the marine macroalgae Ulva exhibited some similar properties as that of rice starch, which was used as reference, such as granule size and amylose content. Potato starch was also used as reference but comparatively, Ulva starch granules were found to be smaller, but with higher amylose content. The high amylose content in algal starch resulted, as expected, in a higher increase in both storage and loss modulus during heating and cooling, when compared with potato starch. Furthermore, digestibility studies showed that algal starch can be well-digested by human digestion enzymes.

The characterization done in this work for algal starch promotes the use of macroalgae as a new and renewable source for food, in particularly starch.