In 1770 Benjamin Franklin mailed soybeans to John Bartram and praised a Chinese cheese that was really tofu. This episode follows bean curd from its origins in the Han dynasty, looking at three theories: the Prince Liu An legend, an accidental curdling with impure sea salt, and the idea that Chinese cooks copied Mongolian cheesemaking, a theory supported by the shift in wording from rufu, milk curdled, to doufu, beans curdled.

We explain the colloid chemistry of curdling: heat unfolds the soy proteins and coagulants such as gypsum, nigari or GDL neutralize their charges so they bind together. The episode covers the full moisture spectrum from silken tofu and douhua to stone tofu, freeze-dried koya-dofu and stinky tofu. It ends with tofu’s arrival in the West, its use as a political insult by Ted Cruz, Suella Braverman and Markus Söder, and its very low environmental footprint.

• Why tofu spread across Asia alongside Buddhism
• How calcium sulfate, nigari and GDL each create a different tofu texture
• Stone tofu, koya-dofu and other ways tofu was adapted for travel and storage
• Tofu impostors such as almond tofu, Burmese tofu and Japanese egg tofu
• Tofu’s low land use and emissions of 1.6 kg of CO2 per 100 grams of protein