Thermal and acidic denaturation of phycocyanin from Arthrospira platensis: Effects of complexation with λ-carrageenan on blue color stability

Influence of storage temperature on the stability of heat treated phycocyanin-λ-carrageenan complexes in liquid formulations

“…In a previous study, it was shown that pure PC was unstable around its pI due to decreased electrostatic repulsion among PC and that heat treatment has a profound impact on the color stability of pure PC. 14,18 Initially, the protein and PC content in the powder were analyzed, and based on these results, the storage stability was investigated.…”

“…At a pH of 4.5, which is above the pI, λC might attach to some positively charged patches on the PC surface. 18,34 However, increasing the storage temperature from 4 to 25 °C had a remarkable effect on the color appearance and intensity of the heated solutions. Mixed biopolymer solutions heated to 70 °C showed a color shift from turquoise towards a greyish green at a pH of 3.5-4.5, and to a light grey at a pH of 5.0 to 6.0.…”

“…Similar to the prevention of the pI-dependent formation of PC aggregates without the presence of λC, this effect might be related to an increased viscosity, steric interactions among polysaccharide residues, and electrostatic repulsion. 18,31 The second major difference observed in the absorption of PC : λC solutions is the peak at 660 nm. Individual PC solutions had a maximal absorption at 620 nm while decreasing the pH in the biopolymer mixture led to an increasing shift towards the red region.…”

“…With three sulfate groups per disaccharide unit, λ-carrageenan carries a strong negative charge, which seemed to be beneficial for the complexation with PC as the complexes are primarily formed by electrostatic interactions. 15,17,18 Additionally, hydrophobic interactions and hydrogen bonds affect the complex structure. 18 While carrageenan was found to be promising to stabilize PC against heat treatments, far too little attention has been paid to the influence of storage time and storage temperature on these complexes.…”

“…15,17,18 Additionally, hydrophobic interactions and hydrogen bonds affect the complex structure. 18 While carrageenan was found to be promising to stabilize PC against heat treatments, far too little attention has been paid to the influence of storage time and storage temperature on these complexes. However, this is of significant importance, since color stability throughout the shelf life is of high relevance in food formulations.…”