DESALINATION AND COMPOSITION OF SEAWEED (Gracilaria subsp.) AND DRIFT MACROALGAE IN THE BRAZILIAN COAST FOR ENHANCED RESOURCE UTILIZATION

Macroalgae are abundant along the Brazilian coast and their main current economic interest is the extraction of hydrocolloids. However, they are rich in other bioactive compounds and proteins, which are still poor explored. The amount of salt present in macroalgae after collecting them is one of the factors that make it difficult to obtain new products. This study aimed to characterize the composition and reduce the salt content from Gracilaria subsp. (AMG) and drift macroalgae (mixed species) on the northeastern Brazilian coast (AMA). The centesimal composition was carried out according to AOAC methodologies (2020). The salt was removed by osmotic treatment with ultrapure water in solid:solvent ratios of 1:40, 1:60, and 1:80 (w/v), stirring for 6 and 12 hours, and changing the water at intervals of 2, 3, and 6 hours. The content of inorganic matter in the wash water and seaweed was determined by gravimetric method after incineration. The macroalgae studied had 11.58% (AMG) and 12.94% (AMA) of protein, values considered high for red and green algae. AMA had higher ash content (26.82%) than AMG (6.70%). There was no statistically significant difference between the treatment times of 6 and 12 hours, nor for the water change intervals of 2, 3, and 6 hours. Among the ratios, AMA showed greater removal of inorganic compounds at 1:80, while for AMG there was no correlation between the amount of salt removed and the solid:solvent ratios used. The 1:80 treatment with 6 hours and a water change every 3 hours made it possible to reduce the ash content of AMG and AMA by 76 and 52%, respectively. The desalination of macroalgae was efficient under these conditions, in addition to using less water, it reduces the inorganic content that could hinder the production of proteins and other bioactive compounds.