Encapsulation of Pomegranate Polyphenols in Plant-Based Proteins and Bioactivity of Resulting Microparticles

The main objective of this study was to generate protein-polyphenol microparticles on the basis of pea and rice proteins in combination with pomegranate juice. Protein microparticles were prepared as a freeze-dried powder and evaluated for total polyphenols and proanthocyanidins using spectrophotometric methods, and for individual polyphenols using the HPLC method. In addition, they were assessed for antioxidant activity, and IR spectra were recorded to establish structural changes in proteins upon adsorption of pomegranate polyphenols. The potential of the formulated microparticles to inhibit colon cancer cell proliferation (SW1116 and Colo205) was also investigated and compared with pomegranate juice. The adsorption capacity of total polyphenols for both protein matrices were 47%. All compounds had a higher affinity for the pea protein matrix except gallic acid. The highest affinity for proteins had punicalagin, with 88% and 80% for pea and rice proteins, respectively. The microparticles demonstrated antioxidant potential using DPPH, ABTS, FRAP, and CUPRAC methods. Both pomegranate juice and protein microparticles exhibited high antioxidant potential and inhibitory effects on both types of colon cancer cells. Screening of IR spectra of protein microparticles revealed the adsorption of pomegranate polyphenols through changes in protein structures, particularly in regions characteristic of proteins.