Flocculation Method

One of the themes that comes out a lot in these articles is consistency. We will make our best cheese when we can do so in a consistent way, by taking lots of notes and keeping all of our parameters the same as when we made our ‘best cheese ever’ so that it can be replicated.Whilst this is certainly true and a mantra from which I’m not going to retreat, there is a bigger question as to what is consistent. Take, for example, adding a starter culture to milk of a certain temperature and then leaving it for a specified amount of time to become curds and whey –what are the consistencies?

Let’s assume the pan, hob, milk volume, starter culture volume, rennet volume, thermometer and even the timer are all the same as last time, so it feels like we’ve got a very consistent environment. You go ahead and make your cheese, but it’s a bit firmer than when you last made it, or the curds haven’t set in the same time as before… what could have gone wrong?

Surprisingly, a lot has changed since last time: temperature of your kitchen, the humidity of the air, the fat percentage (just fractionally) of the milk you’ve used, the potency of the bacteria in the starter culture, the dilution of the rennet, and so on. You see, no matter how hard we try, there are some elements of cheese making that we just cannot control. And that is where the flocculation method comes in.

The problem in the example above is that we kept the timing of our curd formation consistent but there were so many other elements that were not the same as before. If you left your milk, rennet and starter mix half an hour last time, this time and next – for the same recipe – you will get different stages of set just because of the variables we can’t control. The flocculation method moves us away from ‘leaving it half an hour’ because that’s what the recipe says, and towards scientifically measuring when set is occurring and using that time to perfect the optimum set point for the cheese you want in the conditions in which you are making it.

Flocculation is a scientific term which essentially means particles coming out of suspension and forming a solid – in the cheese maker’s case, which means casein proteins coming out of suspension in the milk and forming curds.What we are trying to do in this method is measure when that actually happens for the cheese we are making, rather than allowing enough time for it to take place, which is what most recipes call for. We need a method of being able to tell when the milk has stopped being a liquid and started being a gel. To do that is as simple as using a light, plastic bowl that will float on the top of your ripening milk.Follow these simple steps:
1.   Find and note the flocculation multiplier for your cheese (see below)
2.   Take your bowl and make sure it’s sterilised prior to using it on the milk
3.   Add the rennet to your milk/starter mix in the usual fashion
4.   Make a note of the time you added the rennet
5.   Start a stop watch or timer – you need to know how long the setting takes
6.   Place the empty bowl on the surface of the milk
7.   Gently tap/push it on one side, and note how freely it moves (like a boat across water)
8.   Every minute or so, give it another push and see how it is moving
9.   Soon the bowl will move more slowly as the curds start to form
10.  Eventually the bowl boat will not move at all when you tap it
11.  Note the time on your stop watch; this is your flocculation time
12.  Multiply the time on your stopwatch by the flocculation multiplier from the first step
e.g. 14mins to flocculation x 2.5 flocculation multiplier = 35minutes
13.  Add the result to the time you noted at step 4; this is your curd cutting time
e.g. Rennet added at 2.13pm, plus 35 minutes: cut curds time = 2:48pm 

You should expect to see flocculation occur between 12 and 15 minutes after the rennet is added. If it’s longer than that, then perhaps the amount of rennet is not enough and vice versa if the set is happening within 10 minutes of adding the coagulant. Always record what happens with your cheese making and you’ll be able to see what has an impact on the flocculation time – is it longer or shorter when you make cheese in the winter; what’s the impact of a long dry spell versus torrential rain outside; is there a big impact when you change milk brand… you get the idea.As we saw above, we need a multiplier to make effective use of the recorded flocculation time. As a general rule, softer cheese has a higher multiplier so that more moisture is held in the curds at the point we come to cut them (if you don’t know why, then you need to read about how rennet works). The following will give you an idea of multipliers, but you should check this resource for more detail, look for the pdf in reply #15 from DeeJay Debi.Swiss, Parmesan, etc = 2-2.5 (if floc time is 12 minutes, cut curds 24-30 minutes after adding rennet)
Cheddar, Gouda, etc = 3-3.5  (if floc time is 12 minutes, cut curds 36-40 minutes after adding rennet)
Blue, Halloumi = 4                (if floc time is 12 minutes, cut curds 48 minutes after adding rennet)
Brie, Camembert = 5-6          (if floc time is 12 minutes, cut curds 60-72 minutes after adding rennet)For the next cheese you make, have a go at following the flocculation method and compare the time it gives you to the time your recipe provides. You might be surprised at the difference.Now, if you’re ready to take your cheese production to the next level in terms of control over quality, then you need to be thinking about understanding acid which is where the artisans make the difference from the home producer.