Enhancing acid stability of phycocyanin via non-covalent interactions with gelatin matrices of different Bloom values

The poor acid stability of phycocyanin (PC) restricts its application in acidic beverages. This study investigated the effects of gelatin matrices with different Bloom values (50, 120, and 180) on the stability of PC at pH 3.0. All gelatins formed non-covalent complexes with PC (PG), but their protective effects were non-monotonic. Rheological analysis showed that 120-PG exhibited the lowest loss factor, indicating the formation of a more elastic and homogeneous network than those of 50-PG and 180-PG. Correspondingly, circular dichroism revealed that 120-PG retained the highest α-helix content (46.1%), whereas 180-PG exhibited a pronounced loss of α-helical structure. Spectroscopic analysis further confirmed enhanced chromophore preservation, as evidenced by the greatest increase in A₆₂₀ (17.4%) for 120-PG. Collectively, these findings demonstrate that the enhanced PC stabilization was closely associated with the viscoelastic properties of the gelatin network, with 120-PG providing the most effective conformational preservation among the tested systems.