There’s a tongue-twister in English about “Theophilus Thistle”, or as I pictured it as a child, “The Awfulest Thistle”:
If Theophilus Thistle, the successful thistle sifter,
In sifting a sieve full of unsifted thistles,
Thrust three thousand thistles through the thick of his thumb.
See that thou, in sifting a sieve full of unsifted thistles,
Thrust NOT three thousand thistles through the thick of THY thumb.
It kept coming to mind as I toured Portugal last month, since the Portuguese have a special fondness for using thistle rennet in their cheeses. (I talk a lot more about this in Episode 6.) They’re not the only people to do so, though: their neighbors in western and northern Spain often do as well. The rennet can be made with the purple stamens of the flowering thistle, but the leaves of some plants also contain the same protein-metabolizing enzymes. And these have an effect on a very different cheese made far to the north of Iberia: Cornish Yarg.
Yarg is not common on North American cheese counters, but it’s a somewhat famous oddity in the cheese world due to being wrapped in nettle leaves
There are a bunch of cheeses that get wrapped in leaves—fruit and nut tree leaves are more common though.
Nettles themselves aren’t a common food in North America, but have been used much like other leafy vegetables all over Europe for thousands of years. They happily grow wild in many places that are difficult to farm, which has been important for people living on marginal lands.
In such places, where plant cultivation is minimal, livestock agriculture is key to subsistence. And in most subtropical regions of the northern hemisphere, that also means a diet heavy in dairy and cheese, as those are more renewable sources of protein than meat.
How useful, then, that nettles and thistles can also coagulate milk! No need to kill very young animals that don’t have much meat on them and then have to cure their stomachs while (in some regions) following your herds in a foraging circuit, with no fixed house or barn. Unlike animal rennet, plant rennets are relatively easy to make at need and don’t require long-term storage.
But you’ll often see comments about plant rennets making cheese bitter as they age. And it’s true that plant-rennet cheeses today are most commonly found in traditionally hardscrabble regions, cuz who would want to eat bitter cheese if they didn’t have to?
But this bitterness claim didn’t exactly jibe with what I found in actually eating a range of Portuguese cheeses last month, virtually all of which are made with cardoon rennet. No bitterness even in the harder ones. So is this bitterness trope just a snobbish old wives tale?
Upon further digging I found the key to the “bitterness” claim lies in the type of milk used: in Ep 4 I talked a bit about how milk from different species are structurally different. The range of flavors that cheeses develop as they age is a byproduct of the breakdown of the fats and especially proteins in the milk. And in Iberia, especially in the places fond of using cardoon rennet, they mostly make sheep and goat cheeses.
I’m going to get gross here for a minute. You know how different people in your family have different- smelling farts even though you all eat the same food? It’s because each of you has your own unique set of gut bacteria, which break down your food in slightly different ways. Each metabolizes different parts of the compounds in your food, some more efficiently than others, and with different byproducts as a result. Same thing with the cultures and rennet in your cheese. Cow milk in particular often contains more long-chain proteins than sheep or goat and its proteins can produce a set of bitter peptides under the influence of cardoon (thistle) rennet, while sheep and goat milk do not.
In Ep 2 I talked a little bit about rennets, about how in mammal stomachs we have two major enzymes, chymosin and pepsin, that do the first-pass food breakdown. With animal rennet, the source animal is slaughtered when the ratio is mostly chymosin. Pepsin is a much stronger enzyme that comes to the fore as the animal starts to consume solid food.
Plant rennets have no chymosin, and unlike animal rennets, which exhaust themselves fairly quickly, leaving most of the long-term aging to the remaining cultures, plant rennets keep going and going…
So you get faster, more aggressive proteolysis, or protein breakdown, with plant rennets.
But back to yarg: although it’s typically made with cow milk and animal or microbial rennet, it’s often soft and creamy on the outside, directly under the leaf wrapping, and firmer/crumbly in the interior. That’s because the nettle leaves are breaking down the part of the cheese they’re in direct contact with, faster than the enzymes present in the rest of the cheese.
Originally tweeted by IntoTheCurdverse (@curdverse) on June 18, 2022.
ADDENDUM
I thought I’d add a pointer to US-made nettle cheese I had the pleasure of meeting a few years ago: “Nettlesome” from Valley Shepherd Creamery in New Jersey. Although they’re primarily a sheep farm, this particular cheese is a Gouda-style cow milk cheese. Finely minced nettles are mixed into the curds, giving it a slightly vegetal flavor and just a bit lip-tingly experience. I’d suggest pairing it with a dry cider, like Stella Artois. The carbonation and fructose balance out the nettly-ness.
It’s sold in certain specialist cheese shops (we found it in the store at Cowgirl Creamery), but they also sell direct–you can order from them online.
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