Hello Jon,

I looked for "karoo bush", but I found only karoo as a name for

a region in South Africa.

Georg

Hi Georg,

My apologies. The Karoo is indeed a region in Southern Africa, an arid, inland region that you might recognise as corresponding roughly to fairly open varieties of European Maquis or North American chaparral.

The so-called Karoo bushes are very varied, hundreds of species at least, probably thousands if you include all the varied Karoid regions of the country. However, a large proportion of them are very aromatic, by which I mean, not necessarily that they incorporate benzene rings, but that they have a marked aroma, some of them vilely so, some pleasantly, some very much a matter of taste or of extreme distaste.

Chemically the substances that impart the aromas vary widely and are produced by plants of several families, including many in the Asteraceae, Rutaceae, Lamiaceae. Somehow however there seems to be something characteristic to the "Karoo smell", though I could not say just what, and it certainly does vary from place to place. I think I can say with some confidence however that by far the most of the smells are those of lipoid-soluble substances. Some people find the smell to be herbal and bracing. Some like it in their mutton. Some can't stand it.

Not that that narrows it down much of course!

Interesting question. The obvious answer is: it just does, but that's not very helpful. Why does feeding apples to pigs make their flesh taste of apples? Why does taking a beehive to a moor give honey a heather flavour? Why does feeding corn to chickens make their skin yellow? Why does asparagus make my urine smell odd?

Clearly some aromatic compounds (esters, I guess) are assimilated whole instead of being torn apart and rebuilt. This suggests - to me at least -  that they are rare in the diet. Perhaps the local browsing herbivores can make more use of the compounds in question? Handwaving and thumb-sucking, as you might say. Anyway, you're the biochemist....

Hi Jon, i cannot answer your question but must say that Karoo Lamb is the best i have ever eaten, as a chef of 25 years i can safely say i have eaten plenty of lamb from all over the world. When i emigrated to SA a few years back it was one of the first things i tried to grapple with, pairing the Karoo lamb with the right wines and trying to tie in other flavours to compliment the meat, in the end i realised that the best thing to do with the lamb was to pot roast in a potjie and eat with large chunk of bread, the meat speaks for its self and needs no help...if i get an over gamey bit of lamb i sometimes will add some cranberry jam to a light jus which just breaks that gamey flavour........sorry i have digressed from your question.