Sentence:  Yet if he were not there , they would have missed him , as they would have missed the sounds of bees buzzing against the screen door in early June ; or the smell of thick tomato paste - the ripe smell that was both sweet and <WSD>sour</WSD> - rising up from aluminum trays wrapped in fly dotted cheesecloth . 
Meaning of the word marked with <WSD> tags:  one of the four basic taste sensations; like the taste of vinegar or lemons