Deodorization of Spirulina Extracts by Ozone and Activated Carbon: Effects on Volatile Organic Compounds, Bioactive Pigments, Antioxidant Activity, and Sensory Profile

Spirulina extract holds significant promise for food applications, but its characteristic odor limits consumer acceptance. This study evaluated ozone (5, 10, and 25 ppm) and activated carbon (AC; 10, 30, and 50% w/v) treatments for their effects on selected volatile organic compounds (VOCs) in spirulina aqueous extracts, as well as on protein content, bioactive compounds, and antioxidant activities. Neither treatment adversely affected protein content. Ozone treatments significantly increased total phycobiliprotein content (172.5-181.1 mg/g; p < 0.05), whereas AC treatments significantly reduced it (138.5-159.0 mg/g; p < 0.05). Both treatments decreased chlorophyll (13.9-30.6%) and carotenoid (44.6-72.3%) levels, while DPPH and ABTS antioxidant activities varied according to treatment and concentration. AC treatments were more effective than ozone in reducing total VOCs (74.1-79.9% vs. 30.3-55.5% reduction), but 25 ppm ozone achieved the most favorable sensory profile as assessed by trained panelists. Treatments with 25 ppm ozone and 10% AC provided the best compromise between deodorization and retention of bioactive compounds. These findings indicate that both ozone and AC treatments can substantially reduce the undesirable odor of spirulina extracts, thereby improving their sensory quality and application potential in odor-sensitive food and functional products.