I'm probably the least qualified to answer that question, but in the eyes of a food scientist, it would be the use of a biological system to produce a product.
Now, that process may be through genetic manipulation of a product, through genetic engineering, or it may be through traditional crossing or breeding. I go back to my point about cheese and beer and wine. We used a biological system, in that case a yeast or a bacteria, to produce a product.
In my mind, that's what biotechnology is.