December 10, 2012

What I'm Learning About Rennet

Here is a compilation of all my notes on rennet, the key ingredient to making hard cheese.

~ Rennet is a coagulant. Its function is to separate milk solids from milk liquids, i.e. curds and whey.

~ Junket is a weak form of rennet used for making puddings and custards

~ Raw milk naturally separates into curds and whey as it sours. Rennet enables this separation while the milk is still sweet.

~ There are four types of rennet:
  • animal rennet - made from the 4th stomach of ruminant (calf, lamb, or kid) which has consumed colostrum only
  • natural vegetable rennet - made from plants
  • microbial rennet - made from various cultured fungiform microorganisms (molds): Rhizomucor meihiei, Cryphonectria parasiticia, Mucor pusillus, Mucor miehei.
  • recombinant (genetically modified) rennet called chymosin - derived from animal rennet

~ 80 to 90% of the commercial cheeses manufactured in the USA and Great Britain use chymosin

~ Natural vegetable rennet are proteolytic enzymes derived from plants, such as bromelain (from the pineapple) and ficin (from the fig), as well as biosynthetic chymosin.

~ Plant sources of natural rennets: thistle, fig, yarrow, ground ivy, Lady's Bedstraw, to name a few. An extensive list is here

~ Hard cheeses made from vegetable rennet are said to develop a bitter taste as they age, but apparently only in cows milk, not goat or sheep milk.

~ Some cheeses are always made with animal rennet: Parmesan,Grana Padano and Gorgonzola. They must be labeled "Parmesan style" for example, if using vegetable rennet.

~ Chlorine (in water) kills the active enzyme in rennet

~ Rennet cannot make curds in ultra-pasteurized milk because the milk's casein has been denatured due to the high heat involved in the ultra-pasteurizing process.

~ An alternative to renneted cheeses are kefir cheeses. I've not experimented with this but there is lots of information at this website, http://users.sa.chariot.net.au/~dna/kefir_cheese.html. [Sorry it's not a link. The website owner requests permission before linking to their site, which I respect and did in my first kefir post. It's a bit of a hassle though, so forgive the addy with no link. Just copy and paste to go to the site.]

I definitely want to experiment someday with both kefir cheeses and vegetable rennets. I have fig trees, yarrow, and ground ivy (Creeping Charlie) readily available. Recipes for most of these are practially nonexsistent, so perhaps I can start with one of the thistle or nettle recipes. That project is still future, but here are some how-tos I collected from around the internet


A step by step how-to (with photos) for making animal rennet can be found at Dr. Fankhauser's cheese making website, Rennet Preparation

And a few more resources. These actually form my bibliography:


Do you have any tidbits to add? I'd love to hear them.

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What I'm Learning About Rennet © December 2012 

15 comments:

5 Monkeys and a Chick said...

There is so much information and I feel so little time. This world has gone crazy!

Bernadine said...

We've made our own Mozzarella several times and didn't research what type of rennet we used. Your posts are always filled with such in-depth, useful information. It's so helpful. Good luck with making your cheeses and I look forward to posts of your process.

JES said...

Thanks for the useful information. We just made some farmhouse cheddar using the vegetable rennet and it was horrible. I did jump the gun and opened it a week earlier than I should of. It tasted like rotten milk. I am trying to discern if it was the earliness of the cheese or the vegetable rennet (you have noted a difference in taste)… Maybe the latter? I am visiting from the Homestead Barn Hop.

Leigh said...

5M&C, you can say that again!

Bernadine, I hadn't given rennet a thought, except that I read about the vegetable rennet so ordered animal. I was actually amazed at what I learned.

JES, thank you so much for the visit and comment! Interesting about your cheese results. Cheese making is so simple yet so complex. I have a long way to go myself. I figure learning to make cheese will be like learning to make bread, with lots of flops until I learn to get it right!

Andrew said...

Yes, I noticed the caveat on ultra-pasteurized milk when I was working with a cheese kit. Thanks for explaining exactly why they don't work. And I noticed that all "organic" milk is ultra pasteurized. So, I've been wondering if the rules or organic dairy products allow makers to use non-pasteurized milk when making cheese so it can be organic. Or if there is some sort of bacterial concern about using raw milk to make cheese resulting in true organic cheese. I guess the heating of the cheese later would have the equivalent function of the extra pasteurization...

I like the disambiguation on the types of rennet. The wiki article I read on it left my scratching my head.

Woolly Bits said...

I don't know much about cheesemaking, but I read somewhere that people, who used lady's bedstraw instead of rennet, "wove" a sort of net out of the plants and poured the milk through this "net" repeatedly... haven't tried it out myself, though the plant grows in every stone wall over here....

petey said...

Great post about rennet! I've been buying mine online but maybe will give making some a go as we have lots of thistle :)

Laura said...

Interesting that microbial rennet is made from fugus - since I'm allergic to that (violently...), I'll make sure I avoid that when I finally make my own cheese.

How would you know what form is used in "store-bought" cheese? Do you assume that it's the chymosin, or do they have to note what type of rennet they use?

Leigh said...

Andrew, I noticed that too about organic milk, that it is all ultra-pasteurized. The appeal of it producers is that it increases shelf life significantly. For organic producers, whose product likely sells slower, that's a plus. It's also a plus for those who ship their milk any distance. I also read that the process renders the protein useless to the body. IOW, we cannot absorb the protein so it's essentially a worthless product. I would have to research that a little more, but one source suggested that.

Bettina, interesting! That would definitely be something to experiment with.

Petey, thank you! Would love to know how your thistle rennet cheese making goes.

Laura, I would assume it's chymosin unless labeled otherwise. If it's "vegan" then you know it's vegetable rennet. I found one small artisan cheese producer who chose to use microbial rennet, to avoid animal rennet. I'm not even sure where to find that. I reckon if there's a question, contact the manufacturer!

Heather @Cube2farm said...

Beautiful and informative summary! Thank you so much!!!

Lisa/Fresh Eggs Daily Farm Girl said...

New fan here via Homestead Revival. I love this post - making mozzarella is on my bucket list - and hope you'll come share at my weekly Farm Girl Blog Fest: http://fresh-eggs-daily.blogspot.com/2012/12/farm-girl-friday-blog-fest-12.html

We blog about our small farm in Virginia where we raise chickens, ducks and horses as well as a spoiled barn cat.

Lisa
Fresh Eggs Daily

farmer_liz said...

nice explanation of the difference types of rennet. I have only used Chymosin and hadn't really thought about trying to make my own, but I suppose its something that I should consider rather than relying on being able to order it over the internet. I have talked to someone who extracted it from a calf stomach, what a gruesome process, and not easy either. I don't recognise any of those plants except thistle (being in Australia), so I don't know if we have different names for them or they just don't grow here. I'll have to do some more research. I found you on the Barnhop, think I'll have a look around your blog now :)

Leigh said...

Heather, thanks!

Lisa, thank you! We love our homemade mozzarella! I can't even think of buying it anymore. Thanks for the invite for the Farm Girl Blog Fest. I'll see if I can't have something to share. :)

Farmer Liz, thanks. I've always made it a point to buy animal rennet, but I'm not so sure I'd want to make it myself, LOL. Plant rennets seem a better thing to experiment with. I don't know about the scientific names for any of those plants, and suspect you might have different common names. I hope there's a list of Aussie vegetable rennet sources somewhere.

Anonymous said...

I've seen and eaten a soft white curd cheese made using a fig stick and it was delicious. The fig stick was slashed so the latexy juice could come into contact with the warmed milk and it was just used to stir the milk very gently to make the milk coagulate.

And just for info, I know that all the plants you mention are available in Australia with the possible exception of the ground ivy.

Fran

Leigh said...

Fran, thank you for that! Both for the mention about the plants being available in Australia, but especially for that tidbit about the fig stick. The fig sap is just as you say, but it never occurred to me that the sap was the thing to use. This is one I can definitely try.