DOI Serbia časopisi (original) (raw)

Hemijska industrija 2015 Volume 69, Issue 5, Pages: 511-522
https://doi.org/10.2298/HEMIND140711072R
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Effects of pH on the stability of cyanidin and cyanidin 3-O-β-glucopyranoside in aqueous solution

Rakić Violeta P. (College of Agriculture and Food Technology, Prokuplje) Skrt Mihaela A. (University of Ljubljana, Biotechnical Faculty, Department of Food Science and Technology, Ljubljana, Slovenia) Miljković Milena N. (Faculty of Science and Mathematics, Department of Chemistry, Niš) Kostić Danijela A. ORCID iD icon (Faculty of Science and Mathematics, Department of Chemistry, Niš) Sokolović Dušan T. ORCID iD icon (Faculty of Medicine, Niš) Poklar-Ulrih Nataša E. (University of Ljubljana, Biotechnical Faculty, Department of Food Science and Technology, Ljubljana, Slovenia + Centre of Excellence for Integrated Approaches in Chemistry and Biology of Proteins (CipKeBiP), Ljubljana, Slovenia)

The colour variation, colour intensity and stability at various pH values (2.0, 4.0, 7.0 and 9.0) of cyanidin 3-O-β-glucopyranoside (Cy3Glc) and its aglycone cyanidin was investigated during a period of 8 hours storage at 25ºC. Our data showed that pH of aqueous solution had impact on spectroscopic profile of cyanidin and Cy3Glc. Beginning with the most acidic solutions, increasing the pH induce bathochromic shifts of absorbance maximum in the visible range for all examined pH values (with the exception pH 4.0 for cyanidin), while the presence of the 3-glucosidic substitution induce hypsochromic shift. Compared to cyanidin, Cy3Glc has higher colour intensity and higher stability in the whole pH range, except at pH 7.0. The 3-glucosidic substitution influences on the colour intensity of Cy3Glc in the alkaline region. After 8-hour incubation of Cy3Glc and cyanidin at pH 2.0 and 25 ºC, 99% of Cy3Glc and only 27% of cyanidin remained unchanged.

Keywords: anthocyanins, anthocyanidins, cyanidin, cyanidin 3-glucopyranoside, colour variation, colour intensity, stability, Brown index, UV-Vis absorption spectra