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Petunidin Derivatives from Black Goji and Purple Potato as Promising Natural Colorants, and Their Co-pigmentation with Metals and Isoflavones

Tang, Peipei
http://orcid.org/0000-0003-2613-5846
http://rave.ohiolink.edu/etdc/view?acc_num=osu1523911769211136

Abstract Details

2018, Doctor of Philosophy, Ohio State University, Food Science and Technology.
Color is an important factor in consumer perception and quality of food products. Although extensively used in food industry, artificial colorants have been increasingly questioned among consumers due to potential health concerns. With current clean label trends as well as customer demands, manufactures are seeking alternatives for replacement of synthetic dyes. However, there are limited options for stable natural colors. The first overall objective of this dissertation was to explore new sources of natural colorants. We focused on petunidin-derivatives in black goji and purple potato, as they both are rich anthocyanin sources that could be promising candidates for natural food colors; the second overall objective was to explore co-pigmentation between the petunidin-derivatives and metal ions or soybean isoflavones as methods for anthocyanin color enhancement and stabilization. Currently the most prevalent anthocyanin-based pigments were cyanidin and pelargonidin derivatives (from red cabbage, black carrot, purple sweet potato, and red radish, among others). Focusing on these anthocyanidins would limited the innovation of natural colorant application. Therefore, we started from investigating the pigments in black goji, as it was reported to contain abundant petunidin-derivatives. The black goji extracts produced various vivid hues over wide ranges of pH, with red, purple, and blue colors in acidic, neutral and alkaline conditions, respectively. Cis and trans isomeric petunidin-3-p-coumaroyl-rutinoside-5-glucoside were the major pigments. The colorimetric and spectrophotometric traits of black goji anthocyanins were significantly impacted by purity, pH, acylation, and acyl moiety spatial configuration. The cis and trans isomeric petunidin-3-p-coumaroyl-rutinoside-5-glucoside displayed different color properties. They could be served in food products depending on diverse color demands. However, only 12 cis acylated anthocyanins were reported in reviewing the current literatures. We then explored the controlled conversion of trans to cis petunidin-derivative by UV-irradiation, aiming to provide an efficient method to obtain cis isomeric anthocyanins. A dose-dependent trans to cis isomerization in petunidin-3-p-cou-rut-5-glu was observed, with trans : cis ratio being dependent on container materials and irradiation energy received. Next, we studied pigments in purple potato since petunidin-derivatives were also reported in it previously. The anthocyanin profile was similar but simpler compared to that of black goji. The extracts exhibited analogous color properties as black goji, but with higher color saturation. We further investigated co-pigmentation between petunidin-derivatives and metal ions or isoflavones as methods to enhance and stabilize petunidin-derivatives. Anthocyanin color and stability were demonstrated to be influenced by metal complexation. Although various types of anthocyanin-Mn+ complexes exhibiting blue colors have been studied, most of these studies mainly focused on cyanidin and delphinidin derivatives at acidic or mildly acidic conditions (pH = 6). We studied the chelation between petunidin-derivatives (extracted from black goji and purple potato) and Fe3+ or Al3+ at pH 7-9. The petunidin-derivatives experienced varied bluing effects and enhanced stabilities, depending on pH, metal source, and anthocyanin-metal molar ratios. Isoflavonoids from red clover (Trifolium pratense) was reported to enhance overall color and stability of anthocyanins in muscatine grape juice and wine through intermolecular co-pigmentation. However, the underlying anthocyanin-isoflavone co-pigmentation characteristics remained to be explored. Soybean isoflavones, being more common in food than red clover isoflavones, could be potential co-pigments for anthocyanins. We demonstrated the co-pigmentation between anthocyanin and soybean isoflavones at pH 3 and 7, enhancing and stabilizing the color of acylated anthocyanins. This study showed petunidin-derivatives from black goji and purple potato as promising sources for natural colorants, producing various vivid hues over a wide range of pH. The co-pigmentation with metal ions and soybean isoflavones could provide food industry with various vivid violet, blue, and green colors with enhanced stability.
M. Monica Giusti (Advisor)
Luis Rodriguez-Saona (Committee Member)
Christopher Simons (Committee Member)
John Litchfield (Committee Member)
194 p.
Food Science
Anthocyanins; Black goji; Purple potato; Natural colorants; Acylation; Isomerization; Co-pigmentation; Clean label; Metal Chelation; Soybean; Isoflavones;

Recommended Citations

Citations

  • Tang, P. (2018). Petunidin Derivatives from Black Goji and Purple Potato as Promising Natural Colorants, and Their Co-pigmentation with Metals and Isoflavones [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1523911769211136

    APA Style (7th edition)

  • Tang, Peipei. Petunidin Derivatives from Black Goji and Purple Potato as Promising Natural Colorants, and Their Co-pigmentation with Metals and Isoflavones. 2018. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1523911769211136.

    MLA Style (8th edition)

  • Tang, Peipei. "Petunidin Derivatives from Black Goji and Purple Potato as Promising Natural Colorants, and Their Co-pigmentation with Metals and Isoflavones." Doctoral dissertation, Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1523911769211136

    Chicago Manual of Style (17th edition)

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This open access ETD is published by The Ohio State University and OhioLINK.