# Chymosin from vegetables - a cheesemaking DIY



## TimT (28/5/14)

I want to crowdsource this one. It's not a brewing question though - it applies to another type of fermentation, cheesemaking.

First some background.

Chymosin is the active element in rennet that allows milk to curdle quickly and separate the fatty curds and the liquid whey cleanly.

Apparently plenty of plants have it: common plant ones include figs (it's in the sap), nettles and mallow.

My success with vegetable rennets has not been that good so far; I've tried a couple of times. I've tried fig sap a few times - the milk does curdle - but very slowly, it apparently takes a day for the clean curdle to happen. (Not sure why).

I'm currently trying to curdle milk (for haloumi) with nettle rennet. What you do is boil nettles in water, stir in a bit of salt (which apparently helps bring the chymosin out), and strain the nettles off. Then proceed as normal with the cheese. My milk is currently uncurdled; I've made three additions of nettle rennet over the past two hours - first at eight, the second at nine when no curdling was evident, the third at ten, still no curdling evident. I think the problem I'm having is that the nettle rennet I made was relatively weak (didn't use many nettles), rather than that I haven't isolated the chymosin or my cheese culture is weak. However, the addition of salt to bring the chymosin out of the nettles is problematic as store-bought rennet isn't salty and the salt actually inhibits a lot of the bacterial culture action. (To try to work around this in my current project I've left the culture in the milk overnight at ambient temp). 

So to my question!

All this makes me wonder: is there a better way to isolate chymosin from vegetables than plucking and boiling? Apparently it's in the sap of the nettles or mallow. Would it be possible to boil these vegetables and then distill the chymosin, rather than adding salt? Or is there a way of producing adequate sap from nettles or mallow just by juicing them? Has anyone else tried a project like this? I'd be fascinated in answers or suggestions as to how I might proceed. Fig sap rennet at the moment is out as the sap is strongest when the plant is fruiting in spring, summer and early autumn - but rennet from nettles or mallow is quite possible as they are plentiful.


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## Camo6 (28/5/14)

I thought this was another spam post for a minute there. Don't mind me, carry on, dear sir.


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## sponge (28/5/14)

The grammar is far too correct and information far too accessible to be a spam post.

Interesting concept though Tim..


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## Pilchard (28/5/14)

I think your getting into advanced chemistry there Tim, I'll do a bit of research tonight after work.

Cheers


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## OzPaleAle (28/5/14)

I remember watching a cheese slices episode and there was a spanish cheese made from rennet from a thistle. Was called La Serena cheese I think, no sure if its only a particular thistle but it looked damn tasty.


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## TimT (28/5/14)

_I think your getting into advanced chemistry there Tim_

You could be right - I posted the same question on a cheese forum I go to (funnily enough, called 'Cheeseforum.org/forum"), and the best suggestion so far has been to 'use ammonium sulfate to precipitate the protein.' I looked that up on wikipedia and it sounds like something more suited to a laboratory than a common kitchen (a centrifuge is involved).


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## mmmyummybeer (28/5/14)

Hi Tim,

I have no idea on how successful you can get with plant rennet but I found some notes that might help.

Extracted from Principle of cheese making, Gilbert Chandler College(Melbourne Uni) 1991

'Research has clearly shown the relationship between concentration of chlorine in water and the loss of milk clotting activity in calf rennet." (May need to make sure your using filtered or chlorine free water for your boiling)

'Factors affecting curd firmness
pH
Curd firmness is greatest at a pH of 5.8
Clotting Temperature
Curd firmness increases with increasing milk temperature at clotting up to about 40C. Above this the nature of the curd changes, becoming more rubbery.
Casein : Fat Ratio
Curd firmness is reduced when casein to fat ratio is decreased (ie milk fat content increased)
Level of Calcium Chloride
Addition of CaCl2 up to a level of 200g per 1000L of milk increases curd firmness. The addition of phosphoric acid to milk has also been found to assist coagulation.
Temperature History of milk
When raw milk is cooled and held at low temperatures its clotting time is increased. The effect of cool aging is reversed by moderate heating or pasteurization.


Calf rennet is by far the best or microbial but maybe you might be able to have some luck playing with the above factors.
Anyway thought Id post in the hope it helps. Good luck


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## mmmyummybeer (28/5/14)

Also found this

PLANT AND BACTERIAL CLOTTING ENZYMES
Milk coagulation from plant sources, ie plant proteases such as papain from the papaya tree, bromelain from pineapple and ficin from the fig tree,lead to extremely bitter cheese - reduced yields and pasty-body. This is because of their highly proteolytic nature. 

Sorry probable doesn't help much and not what you wanted to hear, but could help explain if the cheese ends up bitter.


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## TimT (28/5/14)

No, it explains a bit. In the end my nettle rennet didn't curdle at all, so something must have gone wrong. I have read before that when you use plant rennet you may need to up the temperatures a bit. I guess my concern for this thread is how to extract the chymosin from the plant in its purest form - so you don't have to add salt, for instance.


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## OzPaleAle (28/5/14)

Having a read of this link

http://makingoursustainablelife.com/vegetable-rennet

It mentions not using too hot water or it will denature the enzyme(bit like A & B amalayse in brewing I guess), I wonder if that occurred when you boiled the nettle to extract, maybe a cooler steep could extract, I wonder at what temp it Chymosin denatures.


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## TimT (29/5/14)

That could be the problem.... I'll see if I can get another nettle rennet experiment done soon.


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## OzPaleAle (29/5/14)

Had a quick read and the few references mentioned 60degC so maybe try keeping it under that.


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## mr_wibble (29/5/14)

Just talking crap here, 'cause I have no expereince.

Have you tried putting the nettles through a blender and/or food processor?
Maybe more surface area will help with extraction. Might need some filter papers to get the green out of it though.

And with the leftovers you can make nettle soup. Nettle soup rules.


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## TimT (29/5/14)

We made nettle pesto last year, delicious stuff. I actually want to try a recipe for nettle mead in one of my books; depends a bit on how much more I can harvest this year. Not sure my neighbours would be happy if they knew we are purposefully growing nettles....


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## TimT (29/5/14)

I did think about using the blender; another link I found about using plants to curdle cheese suggested that often the plants would be roughly chopped and thrown in with the milk - that might do it, though it might take a while for all the sap to leach out.


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