Author Topic: Vegetable rennet and chymosin - a crowdsourcing question  (Read 331 times)

Offline TimT

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Vegetable rennet and chymosin - a crowdsourcing question
« on: May 27, 2014, 07:33:39 PM »
Hi guys, got a crowdsourcing question for everyone. This is pretty much a copy of a post I made on a brewing forum because I want to crowdsource it to as many people as possible....

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.
« Last Edit: May 27, 2014, 09:00:26 PM by TimT »


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Offline linuxboy

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Re: Vegetable rennet and chymoism - a crowdsourcing question
« Reply #1 on: May 27, 2014, 09:00:44 PM »
You mean without chromatography or using selective membranes? mmm, you could use ammonium sulfate to precipitate the protein.
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Offline TimT

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Re: Vegetable rennet and chymosin - a crowdsourcing question
« Reply #2 on: May 27, 2014, 09:01:29 PM »
12 o'clock now. Still no curdling.

Maybe I didn't even get enough chymosin from the nettles with the old boil, add salt, and strain method. Damnit!

Offline TimT

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Re: Vegetable rennet and chymosin - a crowdsourcing question
« Reply #3 on: May 27, 2014, 09:02:48 PM »
You mean without chromatography or using selective membranes? mmm, you could use ammonium sulfate to precipitate the protein.

Thanks, Linuxboy - you may have to fill me in on all of those methods! Ideally I'm looking for methods that can be done in the home kitchen without too much trouble.

Offline linuxboy

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Re: Vegetable rennet and chymosin - a crowdsourcing question
« Reply #4 on: May 27, 2014, 09:12:15 PM »
yeah, that's why I eliminated the other two.

prepare a clean extraction and use 50% ammonium sulfate to precipitate.

http://en.wikipedia.org/wiki/Ammonium_sulfate_precipitation

I don't have time to get into it, sorry. Look up some google search for precipitating protein with ammonium sulfate or chymosin ammonium sulfate purification or something similar.

edit: I am not sure how many aspartic protease fractions are in nettles (eg IIRC cardoon has 3 main fractions). If you don't know, use a higher concentration. Go up to 80ish percent to recover all the fractions. They precipitate out at different concentrations.
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Offline TimT

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Re: Vegetable rennet and chymosin - a crowdsourcing question
« Reply #5 on: May 27, 2014, 11:13:05 PM »
I'll check out the possibility of using ammonium sulfate - the link seems like it's a lab process more than an at-home one.

Doing a cheese with homemade nettle rennet probably deserves its own thread but as I haven't really had a success yet I can't do that. Has anyone else had success with this?

I picked the nettles well before flowering, and there would have been plenty of fresh tips in my mixture.... I guess the main problem might be the concentration of chymosin in what I produced. I've just given up on this attempt and heated the milk to make a ricotta - I noticed that at around 45-55 degrees C there was a small amount of curd-strands at the surface of the cheese, sort of halfway between yoghurt and mozzarella. Maybe I should have had the milk much hotter, then.