Improving Thermal and Light Stability of Black Grape Anthocyanins Using Cobalt Complexation

Area of Science:

• Food Chemistry
• Natural Pigments
• Antioxidants

Background:

• Anthocyanins (ANCs) are natural pigments with antioxidant properties, suitable as food colorant alternatives.
• ANC stability is limited by pH, temperature, and light, hindering their application.
• Cobalt ion (Co+2) complexation previously improved ANC pH stability.

Purpose of the Study:

• To investigate the impact of Co+2 complexation on the thermal and light stability of black grape ANCs.
• To assess the potential of Co+2 complexed ANCs as improved natural food colorants.

Main Methods:

• Black grape ANCs were extracted and purified.
• ANCs were complexed with Co+2 (ANC-Co+2) and diluted in buffer solutions.
• Thermal stability was tested at 40°C, 60°C, and 80°C.
• Light stability was evaluated under UV and daylight exposure for one week.

Main Results:

• Co+2 complexation extended ANC half-life by over threefold under thermal stress.
• Complexation reduced ANC temperature sensitivity by approximately 50%.
• Co+2 complexation extended ANC half-life by over tenfold (UV) and twentyfold (daylight).

Conclusions:

• Co+2 complexation is an effective strategy to significantly enhance the thermal and light stability of grape ANCs.
• Enhanced ANC stability makes them more suitable for use as natural food colorants.
• This method offers a promising approach to overcoming limitations of natural food colorants.