Study on Extraction Technology and Stability of Red Pigment in Red Plumeria

Background: Pigments, especially for those red color are widely used in various products and are closely related to human health, however, the study on screening optimal conditions for extracting red pigment from red frangipani is less reported. Objective: This study is aimed to decipher the effects of these factors on the stability of the pigment. Method: We developed an optimized extraction method of red pigment from Plumeria rubra L leaves through different combinations of extractants, incubation time and temperature. Results: Results show that the largest productivity of red pigment is found under the condition of 10% citric acid as extractant at 80°C for 90 min compared to other conditions. The pigment is sensitive to high light and appears to have strong reducibility rather than oxidability. The pigments production is also sensitive to pH value, as well as metal ion strength, such as Al3+, Cu2+, Fe3+, Mn2+, Zn2+, K+, Mg2+, Na+, and Ca2+, whereas the production is inhibited by adding sucrose, salt and soluble starch. Conclusion: We concluded that red pigment is sensitive to external environmental stimulus and internal ion and carbohydrates concentrations, among these factors, a combination of 10% citric acid extranctant together with 80oC for 90 min treatments ensures to obtain the largest productivity of red pigment. This study provides a fundamental basis for the production of natural red plumeria red pigment and the screening for edible pigment varieties.