Whey protein improves the stability of C-phycocyanin in acidified conditions during light storage

C-phycocyanin is a bright blue natural colorant used in food and beverage applications. However, its color stability is poor in acidic conditions under exposure to light. In this work, we study the use of whey protein isolate (WPI) to protect C-phycocyanin from color degradation. Low concentration (0.05-0.1%) WPI addition delayed (similar to 2 days) the color degradation of C-phycocyanin at pH 3.0 over 5-day storage in light. However, the color degradation was aggravated adversely during 5-day light storage when C-phycocyanin mixed with a higher concentration (similar to 1%) of WPI degraded after heat-treatment. The Fourier transform infrared and fluorescence spectroscopy confirmed that structural changes (e.g., alpha-helix protection and transformation from alpha-helix to beta-sheet) of C-phycocyanin due to interaction with WPI. These results, along with quartz crystal microbalance with dissipation technology outcomes, suggest that a low concentration of WPI may help protect C-phycocyanin's secondary structure from becoming damaged during light storage, preventing its color degradation.

Automated summary

Low concentration of whey protein isolate (WPI) can delay the color degradation of C-phycocyanin during light storage at pH 3.0, while higher concentration of WPI may aggravate the color degradation after heat treatment. Structural changes of C-phycocyanin, such as protection of alpha-helix and transformation to beta-sheet, were confirmed through Fourier transform infrared and fluorescence spectroscopy. These results suggest that a low concentration of WPI can help protect the secondary structure of C-phycocyanin from damage during light storage.