Wild Vegetable Rennet

“Blessed be the cheese makers, for they shall inherit the earth!”
Life of Brian.

Want to make your own cottage cheese or cream cheese?

Although you can’t forage milk, without upsetting your local farmer, you can stick to your foraging principles by making wild rennet. What is rennet? Rennet is the liquid you add to milk to ‘ret’ it – simply put it triggers the process of separating the curds (lumps) from the whey (liquid).

You can make rennet from quite a few wild plants. It is slower acting that shop-bought rennet and usually needs to be left overnight to curdle the milk. The best plants are nettle, sorrel and thistle. In Cornwall, they make a cheese called yarg, which traditionally was set with nettle rennet and wrapped in nettle leaves to mature. All thistles in the Compositae family will work, e.g. purple thistles (especially the giant ones), globe artichoke and cardoons. Other plants to try for wild rennet include fumitory, unripe fig sap, or yellow (Lady’s) bedstraw.

Sorrel rennet

Sorrel is what I usually use as I can always find a lot of it at most times of the year and you can use any of the varieties. I run the sorrel leaves through my hand juicer and add 5 teaspoons of sorrel juice per litre of milk. Leave it overnight in a warm place for it to curdle. Then strain it through a muslin cloth or nylon bag until it stops dripping. Keep the whey for cooking. Take the curds and season with salt and pepper to taste. Then pot, and put in the fridge. Add chopped chives, or finely chopped wild garlic leaves, for a seasonal twist.

You can also make a simple sour cream by adding a teaspoon of finely chopped sorrel leaves to a cup of milk.

sorrel-leaves

Be careful not to add too much sorrel rennet. Too much can make the cheese too acidic or cause indigestion. Experiment in small batches until you find the strength you like.

Cardoon rennet

Cardoons contain an enzyme called cynarase which will set fresh sheep’s milk in about an hour. The stamens – bright purple threads – are gathered in Spring and dried. A warm tea (never too hot for the enzymes) is made by adding a small amount of warm water to the thistle stamens and pulverising in a food processor. As it mushes up add a little more warm water to keep it moving. Strain off the resulting brown liquid to use as the rennet. Cardoon sheep’s cheeses have an exquisite flavour and creaminess.

No food processor?

Pulverise your dried cardoon or thistle stamens in a pestle and mortar. Keep in an airtight tin. To make rennet, put 6 heaped spoons of powdered thistle back into the pestle and mortar, and add just enough warm water to cover it. Then repeat the following two steps, 5 times over: Soak for 5 minutes, pound for 5 minutes more adding a little more warm water after each pounding. At the end of this, you will get a dark brown liquid – the rennet. Strain it off and add it to the milk. This amount should turn about 5 litres of milk.

Artichoke seed rennet

The above method works with the stamens and/or the seeds of artichokes, especially if you can get the seeds when they are still white and immature. However I have also had success with old seed. Remove the seeds and pound them with a little water until you have a brown liquid. Use a teaspoonful to a litre of warmed goat or sheep milk. Keep in a warm place or use an insulated flask for a couple of hours until the curds have split.

Quick thistle rennet

Pick a bunch of thistle flowers when they’ve finished blooming and gone brown but before they produce thistledown. Tie the stalks together and hang them, head down, in a warm place to dry. Don’t cut the stems off! When dry, hang the bunch into your milk and leave it until the milk separates.

This thistle has run to down. Pick them before the down appears.

Nettle rennet

Salted nettle rennet will make a semi-hard cheese like feta or gouda.
Brandnetel GroteMethod: Nettles are always best used young before they go to seed. Fill a large saucepan 3/4 full of nettles (Urtica dioica) and just cover with water. The volumes should be about 1:1 (So for 1 kilo of nettles you need about 1 litre of water.) Bring to the boil and simmer gently for 30 minutes, then add 1 heaped tablespoon of salt and stir to dissolve. Strain off the nettles and keep the liquid – your nettle rennet – in a jam jar until you are ready to use it.
Use around 60-100 ml for 1 litre of warm milk, 130-150 ml for 2 litres, 190-200 ml for 3 litres and 250ml for 4 litres. However, remember that the strength of your rennet can vary and the efficacy will also depend on the thickness and fat content of the milk. You will have to experiment!
You can also put a large handful of chopped fresh or a small handful of dried nettle into a muslin bag and infuse it in warm milk. Keep the milk just below body temperature 35 C (95 F) until the milk rets. This is a slower process.
In Cornwall, they make a cheese called yarg, which is wrapped in nettle leaves to mature. If you want to try wrapping your cheese, freeze the nettle leaves first to avoid the stings!

2017 update: I recently read an Open Access paper using nettle leaves to make the cheese. Their method is as follows:

2 litres of whole cow’s milk in a sterilized plastic container with 20 grams of Urtica dioica leaves covered with plastic film, stored in controlled temperature conditions (37C for 24 hours).
After this period of time, the nettle leaves were removed leaving the curd in a strainer lined with a cheese cloth. The curd was strained for 24 hours at 4C.
The cheese was placed in 6 molds of 100 g each. It was lined with a cheese cloth, and a weight of 300 g. was placed on top of the cheese molds as the whey drained out.
The cheeses rested for 24 hours at 4C in a gastronorm grid on top of another gastronorm pan. Every 4 hours, the cheeses were turned over in the same mold and this helped to make the cheese uniform in both texture and shape.
Brine: 2.5 litres whey, 10% (250 g) salt and 0.2% (5 g) of calcium chloride, boiled and chilled at 10C. Cheeses were soaked in the brine for 1 hour and stored at 4C with 75–80% relative humidity.
The brine enhances the flavor of the cheese and acts as a preservative by suppressing the growth of undesirable bacteria and fungus.
Blanched nettle leaves were used to cover the cheeses to enhance their flavor and improve the esthetics.

Fiol, C., Prado, D., Mora, M. & Alava, J.I. (2016). Nettle cheese: Using nettle leaves (Urtica dioica) to coagulate milk in the fresh cheese making process. International Journal of Gastronomy and Food Science, 4, 19-24. Open access. The full paper is published here.

Lady’s Bedstraw (Curdwort) rennet

Cheese made with Lady’s Bedstraw (Galium verum) rennet has a lovely yellow colour and is the texture of marscapone.
This was once the yellow of Cheshire cheese although nowadays they dye it with annatto. For Cheshire cheese it was mixed with calf rennet for a harder texture. It is a slow setting rennet and can take 12 hours. It varies!
Galium verumMethod 1: Chop and lightly bruise your Lady’s Bedstraw stalks and leaves with a rolling pin, then infuse in warm milk (just below body temperature 35 C (95 F) until the milk curdles. A handful should curdle a litre. It is easiest to put the plant parts in a mesh bag and stir it around occassionally rather than trying to strain off the plant with the whey.
Method 2: Chop and bruise your Lady’s Bedstraw stalks. Put in a saucepan and just cover with water. Simmer for 30 minutes. Strain. Try using around 125 ml for 1 litre of warm milk.

Fig sap rennet

Fig sap is a milky white latex. It will set warmed goat or sheep milk. Take a small twig off the end of a fig tree. When you strip the leaves off the sap will start to drip out. Drip in the sap (even just 5 or 6 drops into a litre of warm milk is usually enough) and use the twig to stir it in. Leave aside, covered, for a hour in a warm place until the curds have separated from the whey. Don’t put too much fig sap in as it can make the cheese a little bitter.

(Cheat’s tip: If you have a disaster with vegetable rennet and a batch doesn’t curdle, you can always add a little apple cider vinegar or lemon juice to rescue it!)
If you want a particular cheese recipe just DM me on Twitter @monicawilde

PS According to the ancient Greeks, mint prevents milk from curdling even if you’ve put rennet into it!

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