A new cyanine from oxidative coupling of chlorogenic acid with tryptophan: Assessment of the potential as red dye for food coloring. (30th June 2021)

• Record Type: Journal Article
• Authors: Moccia, Federica; Martín, María Ángeles; Ramos, Sonia; Goya, Luis; Marzorati, Stefania; DellaGreca, Marina; Panzella, Lucia; Napolitano, Alessandra
• Is Part Of: Food chemistry. Volume 348(2021)
• Publication Date: 2021-06-30
• Subjects: Betacyanin-type chromophore -- pH dependence -- Anthocyanins -- Betanin -- Toxicity assessment -- Lipid and aqueous food matrices -- Dyeing; Food -- Analysis -- Periodicals; Food -- Composition -- Periodicals; 664
• DOI: 10.1016/j.foodchem.2021.129152
• Languages: English
• ISSNs: 0308-8146

Abstract

Highlights: A red dye from coupling of chlorogenic acid with tryptophan (CGA-TRP) was prepared. A tryptophan linked benzochromeno[2, 3- b ]indole was identified as the major component. CGA-TRP exhibited high pH and thermal stability compared to anthocyanins and betanin. The sodium salt of CGA-TRP performed well as colorant of various food matrices. The sodium salt of CGA-TRP was not toxic on hepatic and colonic cell lines. Abstract: A red pigment was prepared by reaction of chlorogenic acid (CGA) with tryptophan (TRP) in air at pH 9 (37% w/w yield) and evaluated as food dye. The main component of pigment was formulated as an unusual benzochromeno[2, 3- b ]indole linked to a TRP unit, featuring a cyanine type chromophore (λmax 542, 546 nm, 1% extinction coefficient of the sodium salt = 244 ± 2). The chromophore showed a minimal pH dependence and proved stable for at least 3 h at 90 °C, both at pH 3.6 or 7.0, whereas red wine anthocyanins showed a substantial (30%) and betanin a complete abatement after 1 h at the acidic pHs. An intense coloring of different food matrices was obtained with the pigment at 0.01 % w/w. No toxicity was observed up to 0.2 mg/mL on hepatic and colonic cell lines. These data make this dye a promising alternative for red coloring of food.