Abstract
This study aimed to determine how different forms of lutein found in nature affected their thermal stability, degradation, and antioxidant activities. The findings show that commercial lutein (CL) degraded faster than silk luteins (SLs) at ≤ 4 °C. The two-stage first-order kinetics of thermal degradation showed that Ea for SLs was 4.6-9.5 times higher than CL. However, at ≥ 25 °C, both the CL and SLs degraded rapidly within one month. SLs had half-life at 4 °C from 10 to 104 wks. FTIR and HRMS analysis revealed that their oxidation products were similar (C(18)H(26)O(2): 297 m/z). Based on IC(50), antioxidant activities of SLs were superior to CL. The stability and antioxidant capacity of lutein may be influenced by its naturally occurring forms. The naturally occurring forms and unpurified state of lutein can affect its stability and antioxidant activity, which must be considered when storing lutein at different temperatures.