Could be referring to Umami (most commonly translated as savory), one of the primary flavors with dedicated tastebuds in the "five flavors" model. (The others being sweet, salty, sour and bitter. Anecdotally, I forgot Umami pretty quickly after learning these in kindergarten, and no one I asked about it to try and refresh my memory could come up with any fifth flavor other than spicy (which is something different entirely); I eventually looked it up on Wikipedia, I think during my recent search for terminology related to each of the traditional five senses). I fI remember correctly, tomatoes are specifically listed in the wikipedia article as being high in umami.