An edible red seaweed (Pyropia orbicularis): influence of vacuum drying on physicochemical composition, bioactive compounds, antioxidant capacity, and pigments

Abstract

Drying kinetics, proximate composition, dietary fiber, total phenolic compounds, pigments, amino acid profile, and antioxidant capacity (2,2-diphenyl-1-picrylhydrazyl (DPPH) and oxygen radical absorbance capacity) of a red edible seaweed (Pyropia orbicularis) subjected to vacuum drying at five temperatures (40–80 °C) were evaluated. The experimental drying curves were satisfactorily fitted to the Weibull model. The total dietary fiber (TDF) of this seaweed presented a value of 64.37 g (100 g)−1 d.m. The ratio IDF:TDF was 81.1%. The values for protein ranged between 22.34 and 24.92 g (100 g)−1 d.m. in dried seaweed, and His, Thr, and Pro were the most abundant amino acids. The chlorophyll a content was higher than that for chlorophyll b. Total phenolic content (TPC), phycoerythrin and phycocyanin contents, and carotenoid content as well as antioxidant capacity showed an increase at 70 °C. Moreover, at 70 °C, ΔE presented a value of 15.66. Correlations between the TPC and DPPH values (r2 = 0.899) as well as lightness and hue angle (r2 = 0.776) were found during food drying. This work provides important information about the chemical composition and nutraceutical properties of the Chilean edible red seaweed, P. orbicularis.