Study And Application On The Stability Of Natural Gardenia Yellow Pigment

Objective: As food safety has become more and more concerned by people, many synthetic pigments have been banned or restricted to use because of the serious threat to life. Green and healthy natural pigment has become a new favorite. The gardenia yellow pigment we studied in this paper is a natural yellow pigment that extracted from the fruit of rubiaceae gardenia, due to the fresh color and its’ variety of pharmacological and physiological activity,it is highly favored in the industry. Because of the many unsaturated double bond, the gardenia yellow pigment is very unstable and can easily be influenced by the external factors, affecting the color and stability of raw materials and dyed products. The factors influencing the stability of gardenia yellow pigment were detailedly investigated in study, and three different aspects(natural antioxidants, clathration, pigment complementary) to improve the stability of gardenia yellow pigment were studied, to provide new ideas for the pigment of the practical production and application. Methods: In the first part, the UV spectrophotometry was established to determine the pigment loss rate, and the factors influencing stability of gardenia yellow pigment were investigated to laid the foundation for the later determination. The stability of three kinds of natural antioxidants(tea polyphenols, rosemary acid and grape seed extract) under different light and temperature conditions was investigated.And the effect of the amount of antioxidants on the stability of gardenia yellow was investigated. The color changes of pigment solution and dyed pellets under the action of tea polyphenols were observed to verify the effect of the color protection of the antioxidant; The inclusion compounds with pigment and β-cyclodextrin were characterized by UV scanning, microscopy and DSC. The stability of inclusion compounds under different illumination and temperature was investigated, and the color changes of pigment solution and dyed pellets were observed to confirm the feasibility of the inclusion; The stability of gardenia yellow pigment and curcumin in different polar solution were investigated to confirm the feasibility of two complementary colors.After the two pigment is mixed in a certain proportion, the function of complementary was verified both of absorption value and the color changes from pigment solution and dyed pellets. Through the preliminary investigation combined with orthogonal, looking for the optimum formula of joint action. Results: 1、The absorption value of gardenia yellow pigment is proportional to the content, It is scientific and feasible to use the pigment loss rate as the index of the stability of the pigment. 2、The gardenia yellow pigment is sensitive to strong light and UV light,the pigment loss rate can reach 20 % under strong light in 12 hours and the preservation of light is beneficial to the pigment; The gardenia yellow pigment is sensitive to high temperature, the pigment loss was more than 50 % under 80℃ in 12 hours, low temperature and room temperature had little effect to pigment; Acid and alkali environment would harm the gardenia yellow pigment; The oxidant has a huge destruction on the pigment, the higher the concentration, the more obvious the damage; The effect of reducing agent on pigment was not obvious; Except ferric ions, most of the metal ions had no significant effect on the pigment. 3、Both three natural antioxidants can effectively improve the stability of gardenia yellow pigment, 0.1 % concentration of tea polyphenols in strong light and 60℃in 12 hours can effectively reduce the loss of pigment about 10 % and 15 %, The color changes of solution and dyed pellets showed that the tea polyphenols was very good in the color protection. 4、 Gardenia yellow pigment and β-cyclodextrin can form inclusion complex, and after the inclusion, the stability of pigment in light was greatly improved, under the same conditions of strong light in 15 days, the loss of pigment inclusion was only 38 % and decreased 24 %. The effect of inclusion was not obvious on temperature. The solution and dyed pellets under strong light showed that the inclusion effect was very good.5、The curcumin and gardenia yellow pigment had a obvious complementary effect under the condition of different light, the color of mixed pigments almost didn’t change in 7 days of strong light. But the pigment complementary effect was not obvious under the condition of temperature, and the complementary effect had a little help on dyed products. 6、The combined effect of orthogonal examination showed that the effect of tea polyphenols on the amount of pigment loss was significantly, but ethanol concentration and ratio of pigment pigment not.the optimum formula for tea polyphenols concentration of 0.1 %, ethanol concentration 30 %, gardenia yellow: curcumin 90:10. The pigment solution prepared with the optimal formulation was irradiated by light for 7 days and 15 days, and the loss of pigment was decreased by 40 % and 47 % compared with the blank group. Conclusion: The stability of gardenia yellow pigment was poor, by adding natural antioxidants, the stability of different kind of products of the pigment can be enhanced; The effect of inclusion of pigment under the conditions of light is enormous and can be effectively used in the preservation of all kinds of raw materials and dyed products; The pigment complementary had a remarkable effect to the liquid product of color protection. The optimal formula of combination action can reduce the pigment loss rate significantly. It can be used in the production and application of pigment effectively.