Discolouration usually happens when Philips Avent parts are exposed to food containing dyes or colourings that stain plastic, like tomato sauce and certain green vegetables.
To avoid discolouration, keep parts separate from food, containers and other objects containing food residue during cleaning, disinfection and storage.
Discolouration is also caused by exposure to leftover residue from previous washing/cleaning sessions, specific cleaning agents, direct sunlight and calcium build-up from washing the parts in hard water.
Please follow your Philips Avent product's recommended cleaning, disinfection and storage instructions to avoid discolouration.