Oregano

Oregano is unusual among herbs in that drying improves it. Most soft herbs lose their character on the rack; oregano concentrates, and the dried leaf carries more carvacrol and thymol per gram than the fresh plant does. Traditional Mediterranean practice dries it on the stem and crumbles it in at the point of use, and a recipe that specifies dried oregano is not making a compromise.

There are two quite different plants involved. Mediterranean oregano is Origanum vulgare, in the mint family, and it is the one meant in Greek, Italian and Spanish work. Mexican oregano is Lippia graveolens, in the verbena family, unrelated botanically and noticeably different on the palate: more citrus and a slight resinous bitterness against the peppery warmth of the Mediterranean plant. Latin American chorizo and longaniza formulas often mean the Mexican one, and substituting across the two changes the sausage in a way that substituting one brand of Origanum for another does not.

In charcuterie it belongs to the south. It is a signature of the Spanish and Latin American chorizos, where it sits with pimentón and garlic, and it runs through the southern Italian sausages, the Greek loukaniko, and the Balkan and Turkish traditions. It is rare in the German and Polish work, where its sweeter cousin marjoram takes the same slot.

Carvacrol and thymol, the two phenols that dominate its aroma, are among the more genuinely antimicrobial compounds in the spice cupboard, and oregano essential oil is studied seriously for that reason. As with garlic, the effect at culinary doses in a cured sausage is real but marginal against salt, nitrite, acidity and drying, and it must never be counted as a hurdle.

Doses run from about 0.5 to 3 g per kilo of meat, generous by spice standards because the flavour is herbal rather than concentrated. Rubbed or crumbled dried leaf is the usual form; ground oregano loses its top notes quickly and turns dusty.