Views:6 Author:Site Editor Publish Time: 2021-05-01 Origin:Site
Test on affecting the stability of Hibiscus red pigment
In China, Food Additive Standards Technical Committee stipulates that absorbancy is used to reflect the quality of pigments. In this article, 721 spectrophotometer is used to determine the absorbance of the pigment solution.
1. pH test: take 100ml of Hibiscus red pigment liquid, adding 0.05% of NaOH solution to it with a basic burette. Measure the pH value with and observe its color.
2. Heat-resistance test: take Hibiscus red pigment liquid of pH value of 3.06, 3.26, 3.46 each into a water bath at 30°C , 60°C , 80°C , and 90°C each for 1 hour, and then observing absorbancy with 520nm.
3. Light-resistance test: explode different pH value of Hibiscus red pigment under natural light of for 24hour, 48hour, 72hour and 96h, and then observing absorbancy with 520nm.
4. Metalion test: take 5ml*10group of Hibiscus red pigment liquid, adding 5 ml of 0.035% NaCl, CaCl₂，MgCl₂，ZnCl₂，MnCl₂，CuCl₂，FeCl₃，SnCl₂，SnCl4，AlCl₃ each, and then observing its color and compare.
Test of chemical stability of Hibiscus red pigment
1. Oxidation-resistance restore test: draw 5ml of Hibiscus red pigment liquid and add 5ml of H₂O₂ and Na₂So₃ with different concentrations. After 2hours , observe the color and absorbance within 490-550nm.
2. Acid-resistance and alkali-resistance test: take 5ml of Hibiscus red pigment determination solution, add 5ml of different concentrations of citric acid and Na₂So₃solution each,
Observing pH value. Observe its color after2 hours, observe them at 480-560nm
Test of stability of Hibiscus red pigment, as food additives
Take 5ml of Hibiscus red pigment liquid, adding Vc and sodium benzoate solutions with different concentrations same volumes. Observe absorbance within 490-550nm.