As far as I understand, the saliva problem has nothing to do with food. The salivary glands in the cheeks are the ones are fried first after radiation, so the amount of saliva is reduced. Then, there are glands under the jaw that produce the mucous, these go later, but in the meantime, they cause the mucous to be really thick and ropey. These are the side effects of radiation. If the mucous is thick and ropey, get your husband to rinse with the baking soda mixture or flat club soda. These cut the mucous and make it easier for him to spit it out. For dry mouth, some people use Biotene mouthwash. (It may be available under another brand name in the UK.) We have also followed the advice we got on this forum and bought a Water Pik. Put a little mucositis mouthwash in the water tank. Use the tongue scraper attachment on a low setting. It will also clear out the ropey saliva.