fresh ginger

The fresh rhizome of Zingiber officinale, and in this library it is almost always fresh: sixteen recipes use it, fourteen of them teas, where a gram or two of sliced root, or a few thin coins, go into the simmer rather than the steep, which is where the recipes draw the heat out of it. The exceptions are the two-kiwi smoothie, where a thumb-tip goes in raw, and the Japanese curry, where a tablespoon of grated root goes in for the last thirty seconds of the sear, enough to take off the raw edge without cooking away the pungency, beside a blend that already carries dried ginger. Fresh and dried are the same plant and, as it turns out, different chemistry.

The heat is gingerol, which is a family rather than one compound; [6]-gingerol is the abundant member. Its structure is fragile: heat it or acidify it and it loses a water molecule to become shogaol, and a 1978 threshold panel established that shogaols are twice as pungent as gingerols. Drying does not weaken ginger. It swaps the abundant, milder compound for a rarer, hotter one, so a gingerbread and a slice of raw root burn in different registers. Both work on TRPV1, the receptor capsaicin uses, roughly two hundred and fifty times more gently than chilli.

What it does once swallowed is narrower than the shelf of ginger shots suggests. In two randomised trials, 1.2 grams sped the stomach's emptying, by half in healthy volunteers, without changing any symptom anyone reported. Ginger's one well-supported use is nausea, and even there the reviewing bodies call the evidence limited. Free 6-gingerol, the abundant one, never appeared in the blood in either of two studies, even after a 2 gram dose; what circulates is its conjugates, and those are gone within hours. So the root goes into these cups for its heat and for the stomach, and the recipes say no more than that. The Journal's note on ginger shots has the numbers.