Background. Spirulina is categorized as so-called super foods, the properties of which are supposed to have a beneficial effect on the human body, and is used as a natural food coloring additive. The aim of the study was to evaluate the antioxidant and osmotic properties of beverages prepared using various forms of commercially available spirulina and coconut water as a natural isotonic solvent. Based on the determined absorption spectra and antioxidant properties of spirulina extracts (three batches of green and two batches of blue spirulina), samples with the highest activity were selected for the next stage of the study. Beverages were made using coconut water (control sample) and green or blue spirulina with increasing additions of 0.1, 0.25 and 0.5 % w/v (seven beverages in total). The polyphenol content, antioxidant (DPPH•) and osmotic properties of the produced beverages were compared.
Results and conclusion. It was shown that drinks based on blue spirulina had higher protein, polyphenol content as well as antioxidant activity, proportional to the share of additive used, than drinks with green spirulina. The osmolality of all drinks ranged from 315 to 336 mOsm/kg H2O, which meets the requirements for isotonic drinks. Drinks based on blue spirulina were characterized by an intense blue color and better organoleptic characteristics compared to green spirulina and coconut water, however, the addition of 0.5 % adversely affected the organoleptic qualities of the drink. The beverages produced can be categorized as functional beverages, well hydrating the body and additionally enriched with valuable nutrients.