Improved thermal stability of roselle anthocyanin by co-pigmented with oxalic acid: Preparation, characterization and enhancement mechanism

• Published in: Food chemistry Vol. 410; p. 135407
• Main Authors: Huang, Jiayin, Hu, Zhiheng, Chin, Yaoxian, Pei, Zhisheng, Yao, Qian, Chen, Jianchu, Li, Dan, Hu, Yaqin
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.06.2023
• Subjects: Anthocyanins - chemistry; Co-pigmentation; Hibiscus - chemistry; Molecular Docking Simulation; Natural colorant; Organic acid; Oxalic Acid; Pigmentation; Roselle anthocyanin; Thermal stability; Thermodynamic parameters; Roselle anthocyanin; Thermodynamic parameters; Co-pigmentation; Natural colorant; Organic acid; Thermal stability
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2023.135407

•Co-pigmentation effects of five organic acids on roselle anthocyanin extract (RAE) were compared.•RAE co-pigmented with oxalic acid (OA) was optimized with promising thermal stability.•OA enhanced RAE thermal stability in terms of color maintenance and anthocyanin contention retention.•Co-pigmentation not only enhanced stability but also fortified color intensity of RAE.•Molecular interactions between OA and RAE were accounted for thermal stability improvement. The enhancement effects of co-pigmentation on thermal stability of roselle anthocyanin extract (RAE) were investigated. The introduction of organic acids maintained color stability of RAE, and RAE co-pigmented with oxalic acid (OA) presented less color fading rates (19.46 ± 0.33 %) and higher redness (41.33 ± 3.51). Subsequently, suitable co-pigmentation concentration (OA:RAE = 1:2) was obtained regarding with lower ΔE (48.70 ± 2.36). Then, improvement behaviors of co-pigmentation on OA-RAE were evaluated. Results demonstrated that OA-RAE exhibited better thermal stability, as manifested by larger retention rates and more favorable thermal degradation kinetic parameters. Furthermore, both molecular docking simulation and experimental structural characterization revealed that hydrogen bonds and other non-covalent bonds made up the main parts of molecular interactions, leading to formation of stable binary complex. As a result, the aromatic ring of RAE was protected. In conclusion, the co-pigmentation of RAE via introduction of OA was effective in stability enhancement due to the generation of molecular bindings.