Stability of Red Pigment in Bougainvillea Petals: Impact of pH, Temperature, and Chemical Agents
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Abstract:
The stability of the red pigment in Bougainvillea petals was examined during key processes such as extraction, preservation, and application, focusing on factors including heating, pH adjustment, and water removal for enzyme and microbial inactivation. The stability of the pigment was vulnerable to these conditions throughout the process. Using a spectrophotometric method, it was determined that the pigment exhibits maximum stability at a pH of 7, a temperature of 60 ℃, and when stored in the dark. The stability of the pigment was more significantly affected by the oxidant hydrogen peroxide than by the reducing agent sodium sulfite. The addition of stabilizers, such as sodium benzoate, sodium bicarbonate, citric acid, vitamin C, and potassium sorbate at a concentration of 0.4 mol/L, helped mitigate the impact of the oxidant on pigment stability. Metal ions such as lead(II), aluminum(III), and sodium(I) did not significantly affect the stability of the pigment. However, silver(I) and bismuth(II) increased the absorbance of the pigment, producing a rosy red color. Copper(II) caused the pigment to turn orange-red, and without stabilizers, iron(III) caused the pigment to turn blood-red. Avoiding contact with these metal ions is recommended during experiments. These findings provide valuable insights for the practical application of Bougainvillea red pigment.
