Author Topic: Calcium Chloride  (Read 2741 times)

cheeseboard

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Calcium Chloride
« on: July 17, 2020, 03:22:03 PM »
Hi everyone, in my cheese making adventure so far, the Mozzarella and Caciocavallo have both been hard to stretch, they just don't want to be elastic.

So I went back to look at the videos and I found one that said you should not use Calcium Chloride in the process, as it will cause this inelastic effect. The instructions I had been following specifically said to add the Calcium Chloride. But maybe that all depends on the type of milk that you're using in the 1st place ? To cap it all, there's also the ph level that determines the elasticity...........

What do people think to add Calcium Chloride or not ?

Offline mikekchar

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Re: Calcium Chloride
« Reply #1 on: July 18, 2020, 12:28:20 AM »
For traditional mozzarella or caciocavello, you should use calcium chloride if you are using pasteurised milk.  There is a lot of confusion about this, but I'll try to explain.

Milk contains a protein called casein.  This is the protein that makes cheese.  The protein wrapped up in tightly wound balls called "micelles".  You can think of it like a ball of string.  Of course, these balls are too small to see without a very powerful microscope.  Inside the balls of string, there is a salt called calcium phosphate.  Almost all of the calcium in milk is wound up in these balls.  In my mind, I kind of think of it like maybe taking some yarn and putting a whole bunch of chalk on it.  Then you wind up the yarn really tightly in a ball.  Most of the chalk is wrapped up in the ball.  Even if the ball of yarn was wet, the chalk stays on the inside.

This is pretty much how milk is made up.  It's water with these balls (micelles) of casein that wrap up almost all of the calcium.  There are also globules of fat floating around and also a small amount of other proteins (called albumins).  In fact, the reason milk is white is because of the calcium salts wrapped up in the casein.  You might have noticed that when you make cheese, the curds are white, and the whey goes clear.  This is because almost all of the calcium ends up in the cheese -- because it's wrapped up in the balls of protein and not dissolved in the water.

The balls of casein protein (micelles) have another feature.  They are covered in hair like protein.  It's just another form of the casein protein called kappa-casein.  This hair has an electric charge -- it is positively charged.  I don't know if you've played with magnets before, but if you put the north pole of a magnet to the south pole of another magnet, they will stick together.  But if you put 2 north poles together, they will repel (quite a lot!).  The same is true here.  Because all of the micelles have an overage positive charge, they repel each other.  For complicated reasons, it also lets them stay suspended easily in the water (they are "hydrophilic").  This keeps them floating around independently in the water.

Rennet, or more properly, chymosin (which is the active ingredient in good rennet) is an enzyme.  An enzyme is a chemical that can break apart other chemicals.  In this case, chymosin cuts the hair off of the balls of casein.  When that happens the micelles no longer have an average positive charge.  They have an average negative charge.  Of course, this doesn't really make much difference!  They still repel each other because they have the same charge.  They are also still hydrophilic (easy to suspend in water).  However, if you have dissolved calcium in the water, something interesting happens.

Calcium, when it is dissolved in water, has a positive charge.  This will allow it to stick to the micelles.  And then other micelles can stick to *that* calcium.  It forms a kind of chain reaction where the calcium is like glue between blocks.  This is how the curd forms.  The strength of the curd depends on how many micelles the rennet was able to give a haircut to and how much calcium is available to glue everything together.  If you don't have enough calcium, you will not get a curd at all!

But why wouldn't you have a enough calcium?  There is *lots* of calcium in milk!  But, as I stated earlier, it's all wound up inside the micelles!  It is not dissolved and available to be used as glue outside of the micelle.  Usually there is enough dissolved calcium in raw milk to set a curd.  However when you heat water that contains calcium phosphate, it comes out of solution.  This is exactly the same thing that happens when you have chalk or gypsum in your water (hard water).  When you heat it, it comes out of solution and makes  hard water stains and scale on your tap, etc.  When we heat milk to pasteurise it, some of the calcium comes out of solution and usually there isn't enough left to set a curd.  This is why we add calcium chloride.

Thinking about how calcium acts as a glue for keeping the micelles together, you can understand why some people think it's a bad idea to add calcium chloride for pasta filata cheeses.  The more calcium you have dissolved in the milk the stronger the curd.  The stronger the curd, the harder it might be to stretch.  The recommendation for *not* using calcium chloride comes from a very different source, though.

Many people try to make "quick" mozzarella.  You add acid to the milk, heat it and then add rennet.  Rennet works very quickly in acid environments and so the curd sets very quickly.  Because you are at the right acidity to stretch the curd, you can move to stretching it right away, rather than waiting for the culture to acidify the milk.  However.... where does the calcium for setting the curd come from?  The answer is that it comes from the micelles.

Recall that the casein micelles contain a *lot* of calcium phosphate.  However, it's wrapped up inside the ball and is not available.  However, when the micelle is in an acidic environment, it loosens up.  This is actually what allows the cheese to melt and stretch at those acidities.  As it loosens up, calcium phosphate escapes and dissolves in the milk.  So when you are making quick mozzarella, you run the risk of having *too much* calcium dissolved in the milk.  If you add calcium chloride and then add acid you get more calcium coming out of the micelles.  Then you add rennet and -- bang!  A super hard curd that is difficult to stretch.

The only problem is that the amount of calcium that will be available is kind of random and depends a lot on the milk.  Whether or not you need to add caclium chloride to set a good curd for quick mozzarella is hard to know ahead of time.  It's another reason why I think it's not a great technique to use -- it's very prone to failure and the failures are pretty difficult for the average person to understand.

Anyway, I hope that answers your question, though.  You should add calcium chloride.  Generally speaking, you should always add an amount of calcium chloride that allows you to get the curd set that you want in the time that you want.  This will ensure that you neither have too much or too little.  It takes some practice to get that balance between rennet, culture, calcium chloride for you milk, but once you get there, you only ever need to tweak it slightly.  If you start using different milks, it can be frustrating to have to recalibrate again, though.

cheeseboard

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Re: Calcium Chloride
« Reply #2 on: July 23, 2020, 04:11:11 PM »
Wow, that's a very comprehensive answer !

I always wondered why there's calcium in milk and we have to add calcium. Now I know !!

Will have to read that a few times to let it sink in, very useful information.