Most of the databases have a thesaurus that yields subject terms, and 'indexes' that are lists of corporate authors, journal titles, and geographic terms. These vary between and among the databases. For example, CAB Abstracts does not include an author name index, but you may search by an author's name and add topics to the search, such as Oliver in the author field and palmer amaranth in 'all text'.
It is a good idea to check to see that you are using the best terms for your topic. The thesaurus also lists variations on terminology-- broader terms are larger in scope; narrower terms are more limited. "Use" means that is the preferred term to use-- UF or "used for" means that the first term is used by preference. Narrower terms are more specific and more limited; broader terms are covering a bigger array of materials and/or are less specific to a particular subject.
For example, in CAB's listing, it shows: Sensory evaluation, with a narrower term of olfactometry. In Food Science and Technology Abstracts, for Mouthfeel, a broader term is sensory properties, and a narrower term is grittiness.