Some preparations of trypsin contain phenol red. Since the product is shipped with dry ice, there could be a significant CO2 build up in packaging. This CO2 may enter the solution and lower the pH slightly, giving an orange (around pH 6.5) vs. pinkish (around 7.3) color. The solution, if orange (acidic) can still be good to use as is, or sodium hydroxide may be added to adjust the pH.