Kinetic study on the effects of sugar addition on the thermal degradation of phycocyanin from Spirulina sp.

Phycocyanin is a source of antioxidants and natural colorants extracted from microalgae. It undergoes color, concentration, and antioxidant activity degradations during heating processes, such as in food processing. The effects of different kinds of sugars as stabilizer and elevation of temperature were studied. Glucose, sucrose, or fructose as stabilizer were mixed in phycocyanin solution, which was heated to 40 °C, 60 °C, and 80 °C for 60 min. Results showed that phycocyanin degraded significantly without any sugar addition. The addition of glucose could increase the activation energy by up to fourfold due to the polymerization of protein phycocyanin by sugar, and glucose could prevent damage of the phycocyanin structure. Phycocyanin underwent discoloration from bright blue to faint blue after heating at 80 °C. Fructose addition in phycocyanin could minimize color degradation at 80 °C, whereas glucose addition could increase the antioxidant activity of phycocyanin by decreasing IC50 up to 18.47%.