Animal Rennet Making at home - WARNING: some photos may be disturbing to some readers

This is my first attempt to make animal rennet at home, for cheese making.

WARNING: SOME READERS MAY FIND THE FOLLOWING PHOTOS DISTURBING, I know I do.

Our two day old lamb died due to 'wounds received' during lambing. This is heartbreaking for me, made worse because it took it's last breath while I cuddled it in my arms. Please understand this is very difficult for me. I didn't enjoy it a bit, in fact I cried buckets. I think a few tears even made it into the photos, sorry about that.

It's important for me that my actions match my values. My values abhore waste. My goal is to start cheese making this year, and one of the things I need for that is rennet. I could go out and buy commercial rennet, but very little of that is made the traditional way, and a great deal of commercial rennet is now from genetically modified organisms. Instead of composting this lamb and going out to support big business and buy their rennet(-like substances), I decided to make rennet at home.



I received David Asher's book, The Art of Natural Cheese Making yesterday. Inside this book, there is a recipe for making rennet from a calf stomach. It will also work for lamb. Perfect timing. I'm following the instructions in this book.

Here's what I've done so far:

The lamb died and I went and had a good cry. This was a mistake because the body had begun to enter rigour by then. This makes it more difficult to work with. I forgot how quickly little bodies go into rigour, as I've almost always worked with large mammals.



The little lamb was about the size of rabbit, and working with it almost identical. For this I used two very sharp knives, a bucket for the compost and a towel to wipe my hands and knives on while working.

Everyone in the house agreed that it was simply too sad to eat the meat, so I focused on extracting the digestive track.



Cut carefully, I slit the skin down the middle. Once I got to the cavity, I worked with my knife to open it up, being careful to not cut or puncture any organs.

The first thing I did was remove the liver and the (can't remember the name right now) green sack that is full of disgusting tasting bile. This bursts really easily and can taint the taste of the whole innards. You can see it here, it's attached to the liver.


liver's a bit dirty because I fished it out of the compost bin to photograph it for you.

Without the liver, this is what the organ cavity looks like:



Not very nice.

Took the digestive track out, and tried to sort out which stomach I'm looking for.



The rennet comes from the stomach just above the intestines.



These are the stomachs... I want the last one. But how to separate between one and the others? Here's my best guess.



Now it's time to cure it. I packed it in fine Kosher salt, and will leave it in the jar for 6 months or longer. The book doesn't say what temperature to store this at, so it's going in the back of the fridge. If I had a cellar, I would probably keep it there instead.



After the stomach has cured, it will be time to dry it. Once it's dry, I can make cheese from it.

This was a very interesting and educational experience. I'm glad something productive could come from sadness. But still, sadness.

Sorry to hear about your lamb. Good for you to stick your values and make good thing out of a bad situation.

Below is the rennet that David suggested we use. He had us do a taste test on two similar cheeses. One with calf rennet and one with vegetable rennet. The taste and the texture were noticeably different. Everyone in the class preferred the cheese with the calf rennet. The rennet tablets below haven't failed us yet and the cheese is wonderful.

Hopefully you can post a review of your lamb rennet once you start using it. My wife and I are very interested in making our own similar to what you did.

So sorry about your lamb. This thread is fascinating, I didn't expect the stomach to be packed in salt.

That's what I did when I made prosciutto (with the hind leg of a pig).

I've been curious about this too, because I've been a part of helping two local guys (my former students) start making cheese here in the Indian Himalayas. Currently they have to buy imported rennet from Delhi, and then it's a bit of a process to keep it consistently cold with irregular electricity through the summer. Then again, being in India, it's probably better not to use animal rennet, because many Indians are vegetarian.

I'm also curious if anyone has links or can recommend a book that explains how to make vegetable rennet. I've read that rennet can be made from nettles, and we do have those here. Then again, it's probably not reliable and consistent enough for commercial cheese production, but still I'd like to know.

Rebecca Norman wrote:I've been curious about this too, because I've been a part of helping two local guys (my former students) start making cheese here in the Indian Himalayas. Currently they have to buy imported rennet from Delhi, and then it's a bit of a process to keep it consistently cold with irregular electricity through the summer. Then again, being in India, it's probably better not to use animal rennet, because many Indians are vegetarian.

I noticed that commercial rennet wants to be kept cool, but haven't had a chance to look into it. Good quality rennet is a specialty item here, and I've never been able to find a shop that carries it.

The stomach, once cured will be inflated with air, and hung to dry. Once dry it should keep at room temperature (so about 20 degrees C) or less for several years. At least that's according to what I've read. To prepare the rennet we break off a bit of stomach, then do something with it in liquid to reactivate the enzymes, then the liquid is added to the milk. I'll know more in about 6 months.

Rebecca Norman wrote:
I'm also curious if anyone has links or can recommend a book that explains how to make vegetable rennet. I've read that rennet can be made from nettles, and we do have those here. Then again, it's probably not reliable and consistent enough for commercial cheese production, but still I'd like to know.

We have a thread about wild rennet. I think it would be a great idea to start a thread about vegetable rennet in general. I'm really curious about this too... yesterday's adventure was not nice at all. I can't see ever being able to kill a lamb just for rennet, so I might run out if I don't have any more young lambs that die of natural (non disease related) ailments. Knowing how to make vegetable rennet would be a great skill to have.

Thank you! I had posted a similar question back in that thread, but then when through a low-net-access time and never got back to it. There is lots of info about vegetble rennet in that thread, thanks!

r ranson wrote:The stomach, once cured will be inflated with air, and hung to dry.  Once dry it should keep at room temperature (so about 20 degrees C) or less for several years.  At least that's according to what I've read.  To prepare the rennet we break off a bit of stomach, then do something with it in liquid to reactivate the enzymes, then the liquid is added to the milk.  I'll know more in about 6 months.

How did it go? I think 2 days old was a bit too young, but I take the opportunity to check out.

Stomach rennet is still done here, but it has become difficult. Imagine... people have to take the baby more than 1 hour drive to the only slaughter house. Then they need to make analyse the stomach, make rennet and come back for analysis! Professionals will often sacrifice the youngs at birth, because they cannot afford to loose the milk (compared to the low price they will get to sell the meat). So they buy rennet....

So only non professionals still do it at home. I don't know how long they keep it in salt here, and will ask. Then they hang the stomach dry.

BUT, this is not the stomach that is used: it is the inside, the dry curd. So the baby needs to have drunk milk before killing it.
The difficulty is also to change the dosage with each batch. The canarian cheese is made with a LOT of rennet, so that it is done in a few hours. The whey was used to wash the material in the days when it was done in the mountain and with no water.

Milk goat is still common enough to find in season, usually before christmas. They weight like 2-3 kgs, as they need to be killed at 10-14 days, before they eat grass.

I do not know what happens if there is some grass in the stomach and if it is of absolute no use for rennet...

r ranson wrote:


Now it's time to cure it.  I packed it in fine Kosher salt, and will leave it in the jar for 6 months or longer.  The book doesn't say what temperature to store this at, so it's going in the back of the fridge.  If I had a cellar, I would probably keep it there instead.

After the stomach has cured, it will be time to dry it.  Once it's dry, I can make cheese from it.    

I asked how they do it in the Canaries, with their strong tradition for making goat cheese.

They put salt and hang it directly for drying.
You have to tighten the 2 ends well with some thread (some people knew how to do a knot with both ends...)
You need to make cheese with previous year rennet, because it takes some time to dry.

Then you open and put the dry stuff in a blendder with just enough water to cover. Bzzzzzzzzz. Keep the liquid refrigerated for the next months. That can be done by hand too, and that can be done each time you want to make cheese too.

Cheese is not made from the stomach but from the dry milk inside. So you need a lamb or goatling, in general between 9 and 12 days old. They must have eaten milk between 10 mns and 1 hour before killing. They must not have eaten grass. If they have, it is still posible to make rennet until they are about 1 month old. You have to let them in a place where they have no access to grass and let them drink milk only during one day.

Curious to know more about making and using home harvested rennet.

I harvested the stomach from a 7 day old male goat. I didn't mean for him to get that old but life happened in between.  He did have some feed in his stomach, so I rinsed out the stomach contents.  Everywhere I have read says to harvest before they have eaten grass-- what will the effects be of him having eaten solids and me having washed the stomach? Will the chymosin be completely ineffective or just diluted?

I have put it on salt in the fridge. I have read it needs to stay there for 6 months --- how did we arrive at that number ? My meat curing experience tells me that the salt will be fully penetrated within 2 weeks for a stomach of this small size.

Thanks in advance for any insight!