That's a testing system that provides scientists with biochemical responses and electronic readouts when a flavor ingredient interacts with their patented receptor, letting researchers know whether or not their flavor enhancer is effective. The receptors are made from HEK293 -- HEK stands for Human Embryonic Kidney cells, with 293 denoting that the HEK was from the 293rd experiment. HEK293 originally came from a healthy, electively aborted baby whose cells were then harvested and cloned.
According to the Weston A. Price Foundation:
"Senomyx's salt taste, savory flavor, and sweet flavors -- as well as all their other flavor enhancers -- are purposefully developed so that they stimulate your taste buds without them actually tasting anything ... Much like MSG, these flavor enhancers operate on the neurological level to produce these reactions ...
Since they are not actually ingredients but rather 'enhancers' they are not required to be listed in a package's ingredients except as 'artificial flavors' ... [And] because very small amounts of the additives are used ... Senomyx's chemicals have not undergone the FDA's usual safety approval process for food additives."