Figure 3 shows the degradation trend of astaxanthin in milk products with different fat-content applying a model for first-order kinetics, as it is possible to observe, pigment degradation followed first-order kinetic with a constant degradation of 0.259 day − 1 and 0.104 day −1 and a coefficient of determination of R 2=0.979 and R 2=0.960 in WM and SSM respectively and their corresponding half-life times calculated from straight-line slope for each sample were 2.7 and 6.7 days.