Studies On Stability Of Carotenoids During Microencapsulation

In this paper,the HPLC analysis method ofβ-carotene was firstly established.Then the stabilities ofβ-carotene of solid state,in solution and in thermal oils were studied, and the reaction mechanism ofβ-carotene was investigated by quantum chemistry methods,while a network was founded as a result.Different samples during microencapsulation of earotenoids could be well analyzed in this paper,and qualitative analysis of eight.isomers was well studied by C₃₀-HPLC.High stabilities were found during heating of nitrogen-protectingβ-carotene of storage.β-Carotene was more stable in THF and dichloromethane,and the isomedzation was inhibited in nitrogen-bubbled solvent,while a simple antioxidant could affect side-reactions except isomerization.In thermally treated oils,the isomerization took place before 2～4 hours.Though linear dependence was found between the natural logarithm of retention ofβ-carotene and time,the one-order kinetics was impossible to explain the reaction ofβ-carotene.Higher stabilities were found in lower heating temperature,lower oxygen-pressure and oils of larger iodine value.Additionally,the antioxidant would protectβ-carotene at lower temperature.Finally the mechanism of thermal isomerization ofβ-carotene was investigated, with a result that the triplet-excitedβ-earotene is a main intermediate of isomerization under mild conditions.As the network was established,it could be found that the triplet-excitedβ-carotene was more easily formed in environment oxygen,with thereby the isomerization,polymerization,and oxidation of the triplet-excitedβ-carotene would easily happen.The functional groups of byproducts were deduced, and the results were in good agreement with the former results.The effect of solvent on network was also calculated,and the phenomenon of solution could be well explained based on these results.