<a href="http://news.bbc.co.uk/2/hi/uk_news/3248822.stm">BBC NEWS | UK | Scientists create ‘perfect’ toast</a>: “Researchers’ found that people think the perfect piece of toast should have partly melted butter patches on it, improving its taste and texture.
“For this to work, the butter should be applied at fridge temperature of five degrees Celsius, the equation shows…
“The equation relates to the critical amount of butter, applied at fridge temperature (approximately five degrees Celsius or 41°F), required to produce this effect.
“H represents thickness, Cp the specific heat, P density, T the initial temperature of the toast, w the weight, and subscript a and b toast and butter respectively…
“‘To produce the patches of butter most people said they preferred, the bread needs to be heated to at least 120°C, and the butter should be used straight from the fridge, applied unevenly within two minutes of the bread coming out of the toaster.
“‘The amount of butter should be about one-seventeenth the thickness of the bread,’ he said.”