Faculty of Technology and Metallurgy, University of Belgrade
Abstract
Our study aimed to preserve the natural blue dye of C-phycocyanin (C-PC)
phycobiliprotein from Spirulina microalgae due to its importance in the food industry. We
incorporated C-PC into hydrogels formed by combining starch and β-lactoglobulin (BLG)
using high-pressure (HP) processing to achieve this objective. Notably, thermal treatment
resulted in the complete loss of colour derived from C-PC.
We performed a comprehensive characterization of the resulting HP gels by rheology
measurements, texture profile analysis (TPA), small-angle X-ray scattering (SAXS), and
scanning electron microscopy (SEM).
Different compositions of binary (BLG/C-PC) and ternary (starch/BLG/C-PC)
systems were processed under high-pressure (HP) conditions reaching up to 4,500 bar. The
C-PC pigment was effectively preserved by mixing BLG and starch with C-PC at pH 7,
maintaining concentrations of 180, 5, and 10 mg/mL, respectively. The same concentrations
of components were retained in the binary systems.
Rheological properties of the gels were determined using a rheometer with
plane/plane geometry, and texture analysis was conducted through TPA. These findings
enabled the assessment of food gel's properties, such as hardness, springiness, chewiness, and
cohesiveness. The structural characteristics of the gels were determined by SAXS, offering
insights into the interactions between C-PC, BLG, and starch after HP processing. Adding CPC
and starch formed solid gels with a larger mesh than the pure BLG gels. SEM scans of the
gel surface revealed that all components influenced the overall morphology of gels. Even at
low concentrations, the addition of starch notably influenced the gels' visual appearance and
mechanical properties. Our investigation highlights the superior effectiveness of HP treatment
in the preservation of C-PC compared to high-temperature treatment, evident in the sustained
colour integrity of the C-PC blue dye
