bliss point
n. The specific concentration of salt, sugar, or fat that makes a food maximally tasty.

Example Citations:
Domestic goddess, Nigella Lawson has named salted caramel as her favourite 'food obsession', declaring a love affair with the class A confectionary 'drug' describing a 'bliss point' when the mix of sugar, fat and salt is just right.
—Fiona Donnelly, "Let salty-sweet sensations rock your palate (recipes included)," News Limited, August 4, 2012

"More is not necessarily better," Moskowitz wrote in his own account of the Prego project. "As the sensory intensity (say, of sweetness) increases, consumers first say that they like the product more, but eventually, with a middle level of sweetness, consumers like the product the most (this is their optimum, or 'bliss,' point)."
—Michael Moss, "The Extraordinary Science of Addictive Junk Food," The New York Times Magazine, February 20, 2013

Earliest Citation:
So, the drives of hunger and thirst are further potentiated by a strong desire for sensory stimulation. But sensory stimulation is not like a light switch, an on-off phenomenon; there are gradations of stimulation, from the barely perceptible through to the overwhelmingly intense. And only when a sensation is experienced at just the right level does it evoke maximum pleasure. This level we call the bliss point.
—Robert McBride, The Bliss Point Factor, Sun Books, January 1, 1990 (approx)

Notes:
Many thanks to reader Michael Vnuk for supplying me with the earliest citation.

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