Tuesday, 20 January 2015
The sweet aftertaste of artichoke
There are lots of phenolics in Globe Artichokes. To be fair, there are lots of phenolics in the plant kingdom more generally. Phenolics are, in chemical terms, compounds with one or more of what chemists like to call 'aromatic rings' and with one or more of what chemists like to call 'hydroxyl groups'.
[The simplest aromatic ring is the one with six carbons and six hydrogens, drawn as a hexagon with every second side with a double line. A hydroxyl group is represented as an O (oxygen) with an H (hydrogen) sticking off one side and the hexagon or something similar off the other.]
Phenolics are produced by most plants as secondary metabolites, that is products not used directly for growth or reproduction, but for things like protection against pests, against excess radiation or add colour to various plant parts. So far we know of 8,000 different phenolic compounds in plants.
Phenolics add some of the more interesting flavours to fruit and vegetables, such as the bitterness and astringency of berries, and give tea, coffee, beer and wine their kick.
One of the phenolics in the Globe Artichoke is called cynarin. It inhibits taste buds that detect sweetness. And as you eat other things afterwards, the cynarin layer in your mouth is gradually removed making everything suddenly seem very sweet. Miraculin does the same thing in the so-called Miracle Fruit.
To test this I went to my local shops to find a fresh Globe Artichoke. Sadly, none to be found. So I thought I'd test a grilled and pickled version, to see if the phenolics survive all that processing.
Turns out they don't. At least in the one I tasted and then followed by a lime. I ventured further afield and eventually found some fresh artichokes (below) which when eaten after boiling caused water to taste a little sweet (although the sweetness emerged a few minutes later) and very slightly made a lemon seem less sour (not exactly sweet, although again, a few minutes later I could taste sweetened lemon in my mouth). Not quite as miraculous as Synsepalum dulcificum, but a little bit fun.
By the way, the artichoke I'm talking about here is the Globe Artichoke, a thistle, Cynara cardunculus (you can see where the phenolic name comes from). The Jerusalem Artichoke, Helianthus tuberosus, illustrated below, is also in the daisy family but not a thistle and more closely related to the Sunflower (Helianthus annuus). And of course rather than the flower head, you eat this, the tuber.
And not all Cynara cardunculus are Globe Artichokes. While there is some debate over what names to use, there are usually two subspecies recognised, one for the Globe Artichoke, the other the Cardoon (it again is usually divided into two varieties, the cultivated and the wild Cardoon).
The Cardoon is also eaten, and was described recently as 'a fantasy dragon of a vegetable: what celery would look like it went through the Looking Glass and ended up in the Game of Thrones' (do check out the photograph in this link - you'll soon get the idea). They taste a bit like artichokes but you eat the stem rather than the heart of the flower head.
Thanks to Janet O'Hehir who many months ago mentioned this characteristic of the Globe Artichoke to me after I wrote about the Miracle Fruit. And the beautiful drawing of an artichoke, Cynara cardunculus var. fortissima, is by Debra Bartlett. It was bought last year by the Royal Botanic Gardens Melbourne Director's Circle for the State Botanical Collection, and resides at the moment on the wall in my office. (I can't track down this varietal name but presume it is a Globe Artichoke.) The flowers photographed are in front of the Alpine House at Kew Gardens in 2011.