Abstract:

In this article, using phycobiliprotein of Nostoc sphaeroides Küting as raw material, the influence of pH,
temperature and light on the chroma and concentration of phycobiliprotien were studied, and established the degradation
kinetics of phycocyanin and its chroma of Nostoc sphaeroides Küting. The results showed that aqueous phycocyanin at pH 3
exhibited almost no characteristic absorption peaks in the visible region, and characteristic absorption peaks appeared and the
peak values gradually increased along with increasing pH, reaching the maximum at pH 6, followed by a gradual decrease.
The characteristic absorption peaks of phycocyanin displayed a slight blue shift at higher pH levels. The Hunter-b value of
phycocyanin was the lowest at pH 4, and its darkest color was blue. There was a significant difference in Hunter-b value at
all pH levels tested. The half-life of phycocyanin at 50 ℃ was 8.09 and 11.05 times higher than those at 60 ℃ and 70 ℃,
respectively and the half-life of chroma at 50 ℃ was 29.17 and 72.74 times higher than those 60 ℃ and 70 ℃ respectively.

Key words: Nostoc sphaeroides Kützing, phycocyanin, chroma, degradation dynamics