Taste

One reason airplane meals taste flat is cabin pressure. Cabins mimic 1,800–2,400 m altitude and dry nasal passages. A 2010 Fraunhofer experiment found sweet and salty taste sensitivity fell ~30%, so airlines emphasize umami and tomato juice.

The West long capped the basic tastes at four. In 1908 chemist Kikunae Ikeda isolated glutamate — the fifth taste, 'umami' — from kelp broth. The 'four tastes' dogma held nearly a century; umami became basic only after its tongue receptors were found in 2000.

Cats cannot properly taste sweetness. A sweet receptor normally works as a pair of proteins, but in cats the TAS1R2 gene is a broken pseudogene, so they cannot make a functional sweet-taste receptor.