Yuzu is a Japanese citrus that smells like mandarin crossed with grapefruit and something floral. Two thirds to seven tenths is limonene, with minor compounds unique to the fruit doing the distinctive work. Limonene taken from yuzu oil calmed the release of inflammatory granules from immune cells in the dish.^[1] In human trials, smelling yuzu lowered negative mood and reduced a saliva marker of stress.^[2] That is one of the better bits of human evidence for any citrus oil.^[2]