Oxidative stability of emulsions made with self-extracted oil from euryhaline microalgae Spirulina and Scenedesmus

The fatty acid compositions and tocochromanol concentrations (alpha-, gamma + beta-, 8-tocopherol and 8-tocotrienol) of oil extracted from euryhaline microalgal strains (Spirulina subsalsa (Spi A), Scenedesmus MKB (Scnd) and Spirulina sp. (Spi B)) were analyzed. The oxidative stability of microalgae-based oil-in-water emulsions at pH 7 was also determined by measuring lipid hydroperoxide and headspace hexanal formation. The content of saturated fatty acids was highest in Spi B oil whereas n-3 linolenic and eicosapentaenoic acids were high in Spi A. No significant difference was reported in the total tocochromanol homolog contents of Spi A and Scnd oils, but it was signifi-cantly higher in Spi B oil. Tocochromanol depletion analysis revealed that 8-tocopherol and 8-tocotrienol had a slower depletion rate than other homologs and that their high content prolonged the hexanal lag phase of Spi B oil-in-water emulsions up to 21 days. The fact that Spi B had the lowest unsaturated fatty acid content and the highest tocochromanol concentration resulted in greater oxidative stability. Spi A oxidized faster than Scnd irrespective of their similar tocochromanol content which might be due to the higher amounts of unstable 18:3 and 20:5 fatty acids. These data suggest that these microalgal oils could have applications in sustainable food systems.