Study On The Correlation Between Structure And Stability Of Natural Pigments And Its Application

The development and application of natural pigments have become the international focus. People try to get natural pigments from animals and plants and search for the biological activities from them, at the same time to relieve and solve all kinds of problems caused by synthetic pigments. But natural pigments are instable. Their color often changes because of light, heat, oxidation, pH, metallic ions, medium polarity, additives, which affect pigmentation of food. Its usage is also limited.From molecular structures of natural pigments, this thesis takes the detailed studies on the correlation between structures and activities of natural pigments, discusses main factors of affecting its activities and mechanism, and further classesnatural pigments to two kinds-----acyclic and aromatic pigments, what's more, wefind there are some difference between two kinds of pigments: (1) Activities. Acylic pigments often fade, while aromatic pigments always change color;(2)Factors of affecting its activities, light, oxidation, increasing of medium polarity are main factors of affecting acyclic pigments' stability, while pH , metallic ions always change aromatic pigments' color; (3) Mechanism. Catalysis caused by light, oxidation and rearrangement for acyclic pigments; but structure's rearrangement or chelation with metallic ions to aromatic pigments; (4)The characteristics of complement of two kinds of natural pigments; (5)The heat of formation of pigments is in inverse proportion to their stability. Then on this basis we put forward a model of forecasting natural pigments' stability and build methods of improving some pigments' stability. Its results are satisfied when they are applied to the production of some color blending wines of low alcoholicity, which will provide the reference for the advanced research and application of natural pigments.