English to Spanish Science Food & Drink dog and cat food

Hi there!
I have problems with "(fos)" in the following list of ingredients. I guess it's an abbreviation, but I'm not sure. Thanks for your help!

Deboned turkey meat, chicken meal, pea, potato, turkey meal, whole dried egg, sunflower oil, sweet potato, flax meal, natural chicken flavour, ocean white fish meal, alfalfa, salmon oil, yeast culture, dried kelp, lecithin, taurine, chicory root extract (fos), pumpkin, cranberries, spinach, broccoli, green apple, blueberries, pears, bananas, yucca schidigera extract, rosemary extract...