Annatto, the seeds of the achiote plant, is used in American cheese as a natural source of orange dye, says Delucacheesemonger. Annatto seeds have a subtle flavor, too subtle to notice in the small quantities used for coloring cheese.
"There are some southern Mexican (Yucatan) dishes where achiote is used in large enough quantity to affect taste," says paulj. "But people usually buy it in a flavored paste form, since the whole seeds are hard and difficult to grind." There are many regional Mexican and Filipino dishes that rely on the seeds for their grassy, earthy flavor, says JungMann.
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