Toasting effects on the lipid oxidation, antioxidants, and pigments of dried laver (Porphyra spp.)

Abstract

The effects of toasting, simulated gimgui (dried and toasted laver) manufacturing, on lipid oxidation and antioxidant and pigment contents of dried laver (Porphyra spp.) were evaluated by peroxide value (POV) and conjugated dienoic acid (CDA) value measurement, HPLC, and spectrophotometry. Dried laver was toasted for 40 or 300 s at 120°C, or for 2 or 5 s at 250°C. The POV and CDA contents were significantly higher in the toasted samples (0.60-0.69 mmol/kg and 2.17-4.20%, respectively) except in samples toasted at 120°C for 40 s, compared to those in the non-toasted samples (0.43 mmol/kg and 1.21%, respectively). Chlorophyll was the most stable pigment during toasting (>90% retention), followed by carotenoids (50-77% retention) and phycocyanins and phycoerythrins (13-73% retention). Porphyran was the most stable antioxidant (>95% retention), and polyphenols, the most unstable antioxidant (24-75% retention). Despite the degradation of pigments and antioxidants during toasting, the dried laver still contained health-benefiting components after toasting.