How to measure culture

[AnnieBakes]

When you’ve got a tiny package of culture that’s supposed to make 100 litres of milk, how do you measure out the right amount of culture for 4 litres of milk?

[Tedybar]

Use the amount the recipe calls for, although you will need less if using raw milk (unless the recipe specially says it is for raw milk).

[mikekchar]

I can't really agree with Tedybar.  That only works if you are using the same culture as the recipe and even then most recipes have *terrible* measurements for culture.

What you want to do is to get the correct speed of acidification in your milk.  The easiest way to measure the speed of acidification without  a pH meter is to time how long it takes to coagulate the milk with a given amount of rennet and at a given temperature.  Normally I'll use the flocculation method (look it up here on in google), but unfortunately most recipes don't give you flocculation timings either.  It's basically a thing you'll have to figure out with experience.

Having said all that, how do you measure the culture for small amounts of cheese?  Well, if you have a very precise scale, you can do that.  Weigh the total amount that you have and use 1/25th of that.  Often it says on the package the original weight.  But even then you need a *very* precise scale.

I make mother cultures.  This works best for cultures that are either mesophilic or thermophilic.  Cultures that are a mix of the two (so called "farmhouse cultures") don't work very well with this technique.  I tend to make my own mixes.

The day before I'm making cheese, I'll take a tiny amount of the culture (the actual amount doesn't matter much) and add it to 500 ml of milk.  I use a new carton of UHT milk for this and I'll disinfect the container I'm putting it.  For a mesophilic culture I'll hold it at 25 C for 12 hours or so.  Do it in the morning and keep an eye on it.  As soon as it gels, stick it in the fridge.  This will keep the pH from getting too low and potentially affecting the blend of bacteria.  For a thermophilic culture I tend to hold it at 42 C.  It will gel in about 8 hours or less.  Thermophilic cultures tend to be more tolerant of low pH, and it gels at a higher pH due to the higher temperature, so you don't have to be so vigilant.  Still it's good to keep your eyes open.

The next day, add 15g of the mother culture per liter of milk (almost exactly 1 tablespoon).  So for 4 liters of milk, add 60 grams (or 4 tablespoons).  Again, I recommend doing the flocculation method and then adjusting the culture rate the next time depending on how it worked out for you.  This technique will give you *much* better control of your cheese and is probably the single thing that improved my cheese making the most.  If you want a blend of mesophilic and thermophilic, then you need to make both starters (you can do them on different days) and then mix them.  The rate you mix them depends on the recipe.  I won't give you general advice, but if you are trying to do that, ask a question here and I'll try to help.  Basically you want most of your culture in the temperature range it is most suited for.  So a cheddar or tomme with a farmhouse culture should have almost 15g per liter of mesophilic and then add an additional 7g per liter of thermophilic.  A butterkase might be the other way around (depending on how you are making it).

The other advantage of this technique is that your culture will last practically forever.

[DrChile]

mikekchar - when you make a mother culture using thermophilic cultures how do you hold the temp at 42?  water bath vs pouring into a yogotherm container?   Water bath seems simpler and less risk of contamination but maybe I feel a yogotherm might hold temps better (i.e. so I dont have to monitor as close i guess).

Also - to clarify- if I wanted to make a farmhouse mother culture using say MA4001 - are you suggesting I should make 2 separate mother cultures of say Aromatic B and a separate Thermophilic culture?  makes sense to me - more robust cultures with two separate cultures that were made at the appropriate temps rather than the MA4001 held at a middle temp...

Thanks
Trent 

[CurdCutter]

The day before I'm making cheese, I'll take a tiny amount of the culture (the actual amount doesn't matter much) and add it to 500 ml of milk.

Question: Is the rate of acidification directly proportional to the amount of culture added?  I've assumed that is true for rennet, is that correct? While we're at it, what relationship would temperature have to acidification rate (

[mikekchar]

DrChile: I ended up buying a yogurt maker for about $35.  It allows me to set the temperature to whatever I want from 25 C to 70 C.  I've even used it to sous vide meat :-)  I recommend that approach if you make a lot of yogurt.  Otherwise, I've used a water bath in a small picnic cooler (usually add 50 C water to the cooler and then add a jar full of milk into the water bath, then close the lid of the cooler).  I've even done it in a thermos many times.  You can get creative.

And, yes, for a "farmhouse culture" (or my definition of it), I recommend maintaining the mesophilic and thermophilic cultures separately and then mixing them when you make the cheese.  I usually end up using more culture when I do that because often one is mostly inactive (and is only used for the enzymes it provides).  For example, I often use a mixed culture like that and the cheese never gets above 32 C.  My thermophilic is quite happy to grow at that temp, but it does so very slowly, so I'll add something like 12 grams per liter of the mesophilic mother culture and 6 grams of the thermophilic -- which totals more than the 15 grams I would normally add if I just added one.  However the thermophilic provides very little contribution to the acidity.  It provides flavor to the cheese later in aging.

Usually when I set out to make a cheese, I'm prepared to make it at least 5 times to get it the way I want.  I have no expectation that the first time is going to work out.  This gives me the freedom to just guess what I need, try it and see how it works out.  Obviously after doing that with a lot of cheeses, I have lots of notes, so I can get a pretty good guess up front now, but I still don't assume the first try is going to go exactly the way I want.  I recommend not worrying too much if you have the split right, or the amount right.  Just make an educated guess, pay attention to how it went and write good notes.

Question: Is the rate of acidification directly proportional to the amount of culture added?  I've assumed that is true for rennet, is that correct? While we're at it, what relationship would temperature have to acidification rate (

Yes.  The more culture you add, the faster it will acidify.  This is why I like to make mother cultures and add them at specific rates (usually 15 grams of mother culture to 1 liter of milk, but it depends on what I'm making).

I'm not sure what you mean about the rennet.

And *in general* the higher the temperature, the faster the acidification.  However, it depends on the culture.  A mesophilic culture will probably hit it's max speed at about 36 - 38 C and then it will slow down to almost nothing at temps over 39 C.  A thermophilic culture will be very slow at 20 C and will ramp up all the way to 50 C or so, and then drop off again at about 55 C.

[B e n]

As a preface I will say I measure culture using tiny spoons, then weigh on a jewelers scale so I can keep precise notes and adjust on the next make. I would like to move on to mother culture this winter, as January/February I tend to make a lot of cheese. The rest of the year I only make it sporadically and a mother doesn't seem to make sense.

The mother culture plan seems better, but I have some questions about it. With the method Mikechar mentioned the amount of starter culture seems to matter less. But I don't really understand why. We know that the bacteria multiply exponentially with time, and acidify as they do so. But the rate of acidification and the rate of multiplication aren't necessarily colinear. Different environmental conditions, milk, starter cultures, and different starting quantity of culture would create mother cultures that don't contain a uniform bacteria count, especially if dealing with raw milk from animals in different stages of lactation. What creates the uniformity in the mother culture?

What is the shelf life on your mothers Mike? 500ml of milk seems like a lot of culture to get through.


If it helps anyone, I use a sous vide and water bath for all the cheese making, I do 2 gallon batches and it's a snap. It would also make mother cultures easy. It will hold a temp within 0.5°f for as long as I want.

[mikekchar]

I tend to make a mother culture 24 hours before I make cheese.  If I get delayed, I might hold if for another 24 hours, but after that, I just make another mother culture.

When I'm making a mother culture from a DVI culture, I add a "tiny amount".  However, in reality, my "tiny amount" is *way* over the normal addition rate.  Consider that normal addition rate 0.1 grams per liter or something like that.  I'm making 0.5 liters, so I need 0.05 grams.  I can't measure anything that small :-)  I pretty much guarantee that I'm adding more than I need.  Then I'm holding it at optimal temperatures for *at least* 5 hours -- usually 8-16 before it goes into the fridge (I put it into the fridge to reduce the acid production because I find that in some multi-culture cultures, going too long can adversely affect the balance).  This means that my 500 ml of mother culture has a cell count that is *at least* as high as a similar whey culture that you get from making cheese.

I haven't made a culture from raw milk, but I *have* made one from other cheeses.  In that case I make an initial culture from the cheese and then reculture it at least 2 times before I use it for making my cheese.  In each reculture, I will take 30 grams of the previous culture per 500 ml of milk -- so *twice* the normal addition rate.  Again, by the time I get to making my cheese, I have a very high cell count.

With this, I find I get very high consistency of my mother cultures.  Definitely dramatically better than when I was using DVI culture directly.  But even then it doesn't always work out.  That's why doing something like flocculation test, or otherwise tracking the pH during the make is still important.  Cheese is a living thing.  You need to pay attention to it.  Mother cultures gives me a better starting point, but it's not a panacea.

Hope that helps!

[B e n]

"This means that my 500 ml of mother culture has a cell count that is *at least* as high as a similar whey culture that you get from making cheese."

This made it click for me. Thank you for the explaination!

[mikekchar]

I forgot to answer the most important question: Why 500 ml at a time?

Answer: Because it's delicious and I eat the rest :-)  Sometimes I do 1 liter mother cultures, use whatever I need for my cheese and then drain the rest to make a lactic cheese.  In fact, I just did that the other day ;-)  If you use homogenised, pasteurised milk, it's easy to drain and captures basically all of the fat.  Drain it for 24 hours, then pack it in a small basket, salt at between 1-1.5% salt and drain it for another 3 days or so.  Then into the cheese fridge for at least a week, carefully flipping every day.  Either encourage wild geotrichum on it, or spray on a bit when it goes into the fridge.  Once you get good at this, it takes basically no time out of your day and so you have delicious lactic cheese as often as you want.  If I had access to goat's milk, I would use it every time, of course!

You can also (surprisingly) do this with UHT milk, but it's a gigantic pain in the bum.  Because the UHT milk has scrambled whey proteins, the curd retains a ton of water and it takes at *least* a week to drain (really closer to 2 weeks).  It can easily get hopelessly covered in mold before it's properly drained.  However, I've managed to do it a few times.  It doesn't really go creamy as it ages, due to the denatured proteins, but it makes a decent cheese.  If you have UHT milk lying around, it's worth a try.  If it goes moldy, though, cut off the mold and eat it early -- not worth the hassle of trying to save it.  Usually with UHT milk, I'll drain it for 24 hours to get this thick, unbelievably creamy, yummy goop.  I'll eat that (unsalted) with bread.

When I'm in cheese making mode, I'll have at least one each of a mesophilic and thermophilic mother culture in the fridge and will make up a new 500 ml every day (rotating through my collection).  That and the cheese I make are all the dairy my wife and I eat (so 250 ml each per day plus whatever cheese we eat).  I did practically nothing this summer, though, so I'm really looking forward to getting back to it :-)

[DrChile]

Thanks!
Appreciate the info (and reviving an older post)

I used mother cultures quite a bit when I was making cheese more regularly and frozen the mother cultures in ice cube trays.  Then I would use them over the period of 6 months or so.  When it was sporadic, my method didn't make sense for me.  However, now that my cheesemaking is kicking up again (AND using the leftover to make a lactic set cheese - brilliant!), i'm going back to the mother cx method.

Trent