Fermenting sprouts, it turns out, smell exactly as you might expect them to smell; they will convince no-one of that brassica’s deliciousness. The chopped stalks of cavolo nero, on the other hand, fermented kimchi-style with green chilli and garlic, after an initial period of cabbagey pungence, enter a sort of late imperial phase during which they smell strongly of truffles (or at least of truffle oil), which, as everyone knows, in turn smell strongly of pig testicles.
Smell (and therefore flavour) is, like poetry, composed of a set of seemingly abstract and subjective connexions which turn out, on closer inspection, to be absolutely concrete and precise. Truffles do not just happen to smell like pig testicles; they have evolved that way to attract the rooting attention which, buried underground, allows their spores to spread. Nor, really, do they just smell like pig testicles; they smell of them, evolution having precisely replicated the chemical component of that heady musk. Remember that when some gourmand invites you to sniff his knobbly fungus.
It is a common piece of inverted snobbery to laugh at the descriptors on wine labels, with their vanillas and leathers and fruits; “it smells of red grapes to me!” is, to be sure, a fine and time-honoured dad joke, and if it keeps him out of the good stuff then all the better, but it ignores the chemical complexity of fermentation and aging, the interplay between grape, yeast, bacteria and wood which makes wine smell, in fact, almost nothing like grape juice. The reason, for example, that this particular red has a strong taste of vanilla is because it contains quantities of vanillin, the same ingredient found in the bean and synthesised for the flavouring, which is thrown up by the wine-making process.
More readily understood is the fact that similar-tasting plants often contain amounts of the same chemical flavourants; the mustardiness of cabbage comes from the same source as that of mustard; anise, aniseed, fennel, dill, tarragon and chervil all have a similar make-up. This might seem obvious, but it is only recently being understood. It’s what leads Heston to things like salmon in liquorice; at a less exalted level, it’s behind the current-ish fad for herbs in desserts, as well as the precise amplification of flavours which marks a lot of good modern cooking.
So what, you may well ask; well, I thought it was interesting, but what I’d really like to know is –
a) what made that kimchi smell of truffles?
b) will the smell ever come out of the jar?
c) can I use it to attract pigs, like the Pied Piper of Hamlyn?