Improving solubility and functional properties of phycocyanin under acidic conditions by glutaminase deamidation and succinylation

The use of phycocyanin (PC), a protein-based blue colorant, in acidic food products is limited by its susceptibility to aggregation at, and around, isoelectric point (pI ∼4). We modified the pI functional properties PC succinylation protein-glutaminase (PG) deamidation. conditions for deamidation were systematically optimized based on attaining high degree modification while maintaining low color loss hydrolysis during reactions. A new protocol combining acidification with mild heat treatment was developed minimize denaturation ensuring efficient termination PG Under optimal conditions, enhanced electronegativity at pH 4–7. Circular dichroism electrophoresis revealed unfolding secondary structure disassembly large aggregates into small fragments after modification. Succinylation further isolated coiled helices single strands. These structural extensions improve molecular flexibility exposed buried hydrophobic groups, particularly succinylated PC. After succinylation, showed increased solubility, surface hydrophobicity, emulsifying foaming abilities, maintained good stability upon heating 4 5; these gains higher Unfortunately, 3, misfolding massive occurred both samples, making their solubility 3 noticeably worse than unmodified However, improved stability, between 5 will allow survive environments processing many common foods.