White blooms can continue to fade overtime. Some can change to a yellow/brown hue over time. Many blooms hold their color well, others can brown over time. White and pastel roses tend to take its natural course to change continuously.

If the look of natural fading is not something you like visually, floral preservation might not be the best option for you.

Please note that no matter the color of your blooms, color will fade as they age.