Production of Stable Anthocyanin-Based Food Colorants from Hibiscus sabdariffa L. by Copigmentation with Different Protein Isolates

In this study, different proteins [pea protein isolate (PP), rice protein isolate (RP), gluten (GP) and whey protein isolate (WP)] were co-pigmented with Hibiscus sabdariffa L. anthocyanins and bathochromic shift, hyperchromic effect and thermal stability tests were performed on the samples obtained. The polymeric color percentage values, which are indicative of anthocyanin degradation during both processing and storage, showed that the samples WPH (%35.86) and RPH (%38.84) exhibited superior anthocyanin stability. The WPH samples provided the highest z values (112.78 K). Furthermore, the RPH samples demonstrated the highest Ea values (47.98 kJ/mol). The FTIR spectrums revealed the presence of prominent peaks at wavelengths of 3000–3500 cm ^− 1 (-OH tension) and 1600–1650 cm ^− 1 (C = O tension). The observed fluctuations suggest the presence of interactions between anthocyanins and proteins. Copigmentation process caused a significant reduction in fluorescence intensity. This suggests that there is strong interaction between proteins and anthocyanins. It was observed that hibiscus extracts copigmented with protein isolates, particularly whey and rice protein isolates, were able to increase anthocyanin stability.