Metal Chelates of Petunidin Derivatives Exhibit Enhanced Color and Stability

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 -methylated anthocyanidin, has not been well documented. In this study, we investigated metal chel...

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Bibliographic Details
Published in:Foods 2020-10, Vol.9 (10), p.1426
Main Authors: Tang, Peipei, Giusti, M Monica
Format: Article
Language:English
Subjects:
Acids
Aluminum
anthocyanin
Anthocyanins
black goji (Lycium ruthenicum Murr.)
Bluing
Catechol
Chelates
Chelating agents
Chelation
Color
Ferric ions
Food science
Fruits
Iron
metal chelation
Metal concentrations
Metal ions
Metals
natural colorant
pH effects
Pigments
Polyphenols
Potatoes
purple potato (Solanum tuberosum L. subsp. andigenum)
Pyrogallol
Stability
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Summary: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 -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 or Fe 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 200°-310°). Fe caused a larger bathochromic shift than Al , 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.
ISSN:2304-8158
2304-8158
DOI:10.3390/foods9101426