Cheese Making FAQs - Adding the right amount of culture


    You'll find that many cheese making books, and online cheese recipes don't include the quantity/amount of cultures you need to use in their recipes. For beginners, this is understandably bewildering, confusing, and not a little off-putting to say the least. You might be asking:

    Why has quanitity forsaken me? Does the recipe writer despise my ordinary mere mortal status?

    Now cultures are grown, not manufactured in a lab, despite appearances. Also, the mere fact that they're still alive (rather than vehemently dead ingredients like sugar or flour in everyday cooking) means that there's a bit of variation from one batch to another. In short, some batches will simply reproduce faster in milk than others. However, in this increasingly technological time and using modern quality control, the labs making these cultures have the ability to measure a batch, and figure out how "active" they're likely to be. Then they do most of the hard work for you.

    Why most?

    Cultures are sold in amounts that will turn a specified amount of milk into cheese. For example, 100L is a common home cheese maker quantity. If the batch is a little lethargic to get up in the morning, then the lab will test this culture, find that out, and simply supply more culture in the packet to compensate. Similarly, if you've got a batch that has dreams of rapid microbial world domination (in milk of course) then they will put less into the packet to make sure you aren't overrun and get the results you expect. As such, weight from one packet to another can vary significantly. I generally try not to rely on volumes too much, as some cultures can be more densely packed than others.. but if you've got nothing else to go on, then that's better than nothing!

    Some culture shops only supply dosage instructions online. Here's one example.
    Some culture shops only supply dosage instructions online. Here's one example. So you may have to look it up, rather than have it conveniently on the packaging.

    Other shops will have it on the packaging, and online. Such as here:

    I have a shiny new packet of culture, how to I add the right amount to my recipe?

    Calculating the "dose" or amount of each culture needed for a recipe is an essential skill for cheese makers. However, you need to do this calculation for every new packet of culture you get, even if you are using the same type as one you used before. Like I said, no guarantees of consistency from one batch to another.

    Essential Equipment:

    Cheese makers typically need very small amounts of cultures (relative to the amount of milk) to make their cheeses. Cultures reproduce exponentially in milk so a little goes a long way. The amounts you will likely need are made smaller again, because as a home cheese maker, you're only making very small amounts of cheese. It's not uncommon to use doses in single millilitres (mL) or fractions of a gram. So here's the first problem. If you have a typical kitchen scale, is it accurate enough? Answer: Probably not! My kitchen scale has a increment of 2g. That is nowhere near the accuracy I need for these tiny amounts of ingredients.

    As such, the only requirement is that you have a very accurate scale. (Think a scale that measures fractions of a gram, usually down to 0.01g increments is fine. They can be bought on eBay for as little as $11-15 Australian (see below) or laboratory grade ones with extra accuracy can be many hundreds, even thousands of dollars.. but that's just excessive. In any case, you need an accurate scale in order to do this.

    eBay page for accurate pocket scales suited for cheese cultures
    eBay page for accurate pocket scales suited for cheese cultures.

    DON'T PANIC, but it's time for the calculation part. (It's simple division, and you can use a calculator)

    Calculations scare many people, but it's really easy if you have the scale. Here's the process:

    1. With a new and unopened packet of culture, (It won't work if you've spilt or used some). Look at the outside of the container, or on the supplier's web site. It will say it's good for a certain amount of milk. (Let's say 100L for ease of calculation, but some bigger packets go way higher than that).

    2. Zero your scale after placing some sort of light weight and sterile container on top (this conveniently excludes the weight of the container from the scales reading). A small plastic jar is the usual, but whatever suitable container is fine, and if they aren't included with your culture order, make sure you order one so you can keep it in a bottle. They're much easier than the resealable bags they often come in..

    Alternatively you can also weigh the empty container first, and deduct it from the combined weight reading after filling it (but that's more maths than you probably want to do).

    3. Pour in all the contents into the container (make sure you get as much out as you can) and weigh it.

    Let's say your scale reads 7.28g worth of culture (more if you included the weight of the bottle too). Whatever the weight is, make a note of it. If 7.28g does 100L of milk, then you need 0.0728 (rounded to 0.07g) per Litre (7.28/100=0.07). However, most people make cheese from 4L or more of milk. Just multiply that 0.07g accordingly for your given milk quantity. Which for 4L is 0.28 grams of culture. When "scooping it out" You won't ever get it perfectly right (unless you're very lucky) but you can get surprisingly close. However, as an added hard-won tip based on my experience, I recommend not doing this under fans, open windows, or sneeze-prone folks as that can blow it away.

    4. Once measured, it is generally helpful to stick a label on your culture container, outlining the full weight, and intended milk volume, calculated dose per litre.

    I'd also recommend that you figure out the most common amount of milk you use, (I use 10/12L, but when I was starting I often used 4-6L) and write the corresponding weight of culture for that amount of milk on your label as well. So you have the correct weight written down when you next make cheese. Some people actually put pre-weighed doses into separate container so it's just "add and go". Whether you do it before hand or "on the day", using very small measuring spoons like the ones shown below to dole out the correct amount (ignoring volume and just doing it by weight) should be close enough to make any culture work with any recipe!

    I hope this solves some much needed frustration and confusion out there. This is something that is not always clearly outlined in cheese making books, (even the ones that omit fixed quantities of culture).

    Happy cheese making!


    P.S. I actually ran off my course notes, and cultures supplied by my instructor for a surprisingly long time, but eventually you will need to source something from someone else, and then you can't guarantee that the batches are the same strength as what the volume-based recipes call for. Volume based quantities can work. However, I wouldn't do that unless the recipe and cultures are from the same source.

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