And now you know why processed foods contains buckets of monosodium glutamate. It's tasty, and we have receptors on our taste buds which responds specifically to it.
If the fifth surprises you, how about the current research suggesting a sixth taste : fatty.
http://www.ncbi.nlm.nih.gov/pubmed/19400700http://www.ncbi.nlm.nih.gov/pubmed/17484372