Open AccessMetal Chelates of Petunidin Derivatives Exhibit Enhanced Color and Stability
Author(s) -
Peipei Tang,
M. Mónica Giusti
Publication year - 2020
Publication title -
foods
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.774
H-Index - 38
ISSN - 2304-8158
DOI - 10.3390/foods9101426
Subject(s) - bathochromic shift , petunidin , chemistry , malvidin , chelation , metal ions in aqueous solution , metal , nuclear chemistry , organic chemistry , inorganic chemistry , cyanidin , physics , quantum mechanics , fluorescence , antioxidant
Anthocyanins with catechol (cyanidin) or pyrogallol (delphinidin) moieties on the B-ring are known to chelate metals, resulting in bluing effects, mainly at pH ≤ 6. Metal interaction with petunidin, an O -methylated anthocyanidin, has not been well documented. In this study, we investigated metal chelation of petunidin derivatives in a wide pH range and its effects on color and stability. Purple potato and black goji extracts containing >80% acylated petunidin derivatives (25 µM) were combined with Al 3+ or Fe 3+ at 0 µM to 1500 µM in buffers of pH 3-10. Small metal ion concentrations triggered bathochromic shifts (up to ~80nm) at an alkaline pH, resulting in vivid blue hues (h ab 200°-310°). Fe 3+ caused a larger bathochromic shift than Al 3+ , producing green colors at pH 8-9. Generally, metal ions increased the color stability and half-life of petunidin derivatives in a dose-dependent manner, particularly at pH 8. Petunidin derivative metal chelates produced a wide range of colors with enhanced stability.