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Evaluating the Effects of Anthocyanin Structure and the Role of Metal Ions on the Blue Color Evolution of Anthocyanins in Varied pH Environments

Sigurdson, Gregory T
http://rave.ohiolink.edu/etdc/view?acc_num=osu1461253897

Abstract Details

2016, Doctor of Philosophy, Ohio State University, Food Science and Technology.
Due to consumer demand and possible health concerns, the use of alternatives for synthetic food colorants has increased. Anthocyanins (ACN) are a class of natural pigments responsible for red to blue colors of edible produce with potential health benefits. In acidic conditions common to foods, ACN appear red-purple limiting their use as blue colorants. However, self-association, co-pigmentation, and metal chelation have been shown to expand their color expression to purple and blue. Metal ions (M+) displace hydrogen ions from B-ring hydroxyl groups, transforming red flavyliums to blue quinoidal bases. The effects of the ACN substitution pattern and role of various M+ on their color evolution have not been fully elucidated in the pH range common to many foods. The objective of these studies was to replicate these naturally occurring reactions and evaluate the ACN response to expand the useful color and pH range of ACN. Acylated and nonacylated derivates of cyanidin and delphinidin were combined with various M+ (Mg2+, Al3+, Cr3+, Fe3+, and Ga3+) in factorial excesses to ACN concentration (0-500×) in pH 3-8. The effects on ACN color expression were evaluated by UV-Visible spectrophotometry (380-700 nm) and CIE-L*a*b* colorimetry (transmission, 10º observer angle, D65 illuminant). ACN responses to M+ chelation were dependent on all factors tested. In all pH, anthocyanins exhibited bathochromic and hyperchromic shifts becoming more blue. Largest bathochromic shifts occurred in pH 6, and largest hyperchromic shifts occurred in pH 5. M+ chelation resulted in larger bathochromic shifts on ACN with more B-ring hydroxyl groups (delphinidin > cyanidin). ACN lacking acylation typically underwent much larger bathochromic shifts; however, the ¿max of acylated ACN with M+ was larger in all cases. Bivalent Mg2+ showed no observable effect on ACN color. Generally, bathochromic shifts on ACN were greatest with more electron rich M+ (Fe3+ ˜ Ga3+ > Al3+ > Cr3+). The ratio of M+ to ACN to induce the largest bathochromic shifts decreased as pH was increased. M+ chelation by ACN resulted in blue and purple hues similar to currently used synthetic colorants in environments where these colors are not typically expressed, indicating potential to act as alternatives.
M. Monica Giusti, Ph.D. (Advisor)
Luis Rodriguez-Saona, Ph.D. (Committee Member)
Christoper Simons, Ph.D. (Committee Member)
Lynn Knipe, Ph.D. (Committee Member)
Chemistry; Food Science

Recommended Citations

Citations

  • Sigurdson, G. T. (2016). Evaluating the Effects of Anthocyanin Structure and the Role of Metal Ions on the Blue Color Evolution of Anthocyanins in Varied pH Environments [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1461253897

    APA Style (7th edition)

  • Sigurdson, Gregory. Evaluating the Effects of Anthocyanin Structure and the Role of Metal Ions on the Blue Color Evolution of Anthocyanins in Varied pH Environments. 2016. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1461253897.

    MLA Style (8th edition)

  • Sigurdson, Gregory. "Evaluating the Effects of Anthocyanin Structure and the Role of Metal Ions on the Blue Color Evolution of Anthocyanins in Varied pH Environments." Doctoral dissertation, Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1461253897

    Chicago Manual of Style (17th edition)

osu1461253897
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© 2016, some rights reserved.Creative Commons License Evaluating the Effects of Anthocyanin Structure and the Role of Metal Ions on the Blue Color Evolution of Anthocyanins in Varied pH Environments by Gregory T Sigurdson is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by The Ohio State University and OhioLINK.