abstract
In many food products, colorants derived from natural sources are increasingly popular due to consumer
demand. Anthocyanins are one class of versatile and abundant naturally occurring chromophores that
produce different hues in nature, especially with metal ions and other copigments assisting. The effects
of chelation of metal ions (Mg2+, Al3+, Cr3+, Fe3+, and Ga3+) in factorial excesses to anthocyanin concentration
(0–500) on the spectral characteristics (380–700 nm) of cyanidin and acylated cyanidin derivatives
were evaluated to better understand the color evolution of anthocyanin-metal chelates in pH 3–8. In all
pH, anthocyanins exhibited bathochromic and hyperchromic shifts. Largest bathochromic shifts most
often occurred in pH 6; while largest hyperchromic shifts occurred in pH 5. Divalent Mg2+ showed no
observable effect on anthocyanin color while trivalent metal ions caused bathochromic shifts and hue
changes. Generally, bathochromic shifts on anthocyanins were greatest with more electron rich metal
ions (Fe3+ Ga3+ > Al3+ > Cr3+).