Effect of Drying Method and Sugar Type (Sucrose, Glucose, and Fructose) on the Concentration and Stability of Phycocyanin During Storage

Phycocyanin is a major water-soluble pigment derived from Spirulina, valued for its strong antioxidant activity and potential as a natural food colorant. However, its stability is influenced by factors such as temperature, light intensity, and pH. This study investigated the impact of different drying methods (freeze-drying, oven-drying, and spray-drying) and different sugar concentrations (glucose, fructose, and sucrose) on the stability of phycocyanin extracted from Spirulina platensis. Additionally, the effect of storage duration (up to 120 days in 15-day intervals) on pigment stability was assessed. Results showed that Freeze-drying resulted in significantly higher phycocyanin concentration and stability than oven and spray drying (p<0.05). Among the treatments, freeze-drying with sucrose yielded the highest pigment retention (p< 0.05). Furthermore, sugar-treated samples demonstrated greater pigment preservation than sugar-free samples, with sucrose outperforming glucose and fructose in all drying methods tested. Overall, the stability and concentration of phycocyanin decreased over time during storage. The degradation kinetics followed a second-order model, with thermal degradation constants decreasing as pH and fructose concentration increased but increasing with temperature. Moderate fructose levels extended the pigment half-life, whereas excessive amounts reduced it. These findings suggest that freeze-drying combined with sucrose addition is the most effective strategy for enhancing phycocyanin stability during storage.