Complex sentence: Along with gliadin (the "gluten" found in wheat) hordein is present in many foods and also may be found in beer, and hordein is usually the main problem for coeliacs wishing to drink beer.
Split into simpler sentences: Along with gliadin (the "gluten" found in wheat), hordein is present in many foods and also may be found in beer. Hordein is usually the main problem for coeliacs wishing to drink beer.