If one aspect of healing time for the curds is reducing fines, the second important element of healing cheese is the impact it has on moisture levels. Academic studies have shown that longer healing times reduce the amount of moisture lost from the curds which, as you know well by now, is a vital element of determining the type and quality of the cheese we end up with.
One important lesson to take from all of this is that as you strive to produce better quality cheese, or even just deliver consistency from one batch of cheese to the next, is that even the seemingly trivial parts of the preparation, e.g. ‘leave the cut curds to rest for 10 minutes’ can have a significant effect on the end result.
In a similar vein, we need to think about why we scald the curds. Scalding (or cooking) is quite simply the process of leaving the cut curds in the whey but under a higher heat than they were formed at and either with or without gentle (so as not to create excess fines) stirring.
If you think that this process might also be about moisture levels, then you’d be right, but that is only part of the answer. It’s true that increasing the heat of the surrounding whey does induce more moisture to leave the curds. If the curds have been given a short amount of healing time, they will lose even more moisture during the scalding phase, deliver a lower yield and lose more fat to the whey than if they spend longer resting.
The moisture loss is most effective if temperature is increased very slowly; the faster the increase in temperature, the more moisture will stay trapped in the curds, never to be released. You may also find that rapid increases in heat causes your curds to form a thicker ‘skin’ than desired, adversely affecting the finished texture of the cheese.
This is another great example of why following recipes closely and, as you become more proficient, taking control of your own cheese making though monitoring variables such as rate of temperature increase, is so vital to the quality of your finished cheese.
There is a third variable that scalding impacts: acidity levels. The amount of acid in your cheese (its pH) directly impacts the flavour of it; too acid and it’s going to be bitter (I have done this numerous times!), not acid enough and it will be bland.
The acidity of cheese is due to bacteria from our starter culture converting lactose into lactic acid. If left to their own devices, those bacteria will just keep doing that until the lactose has all gone. One way to stop them creating more acid in your curds is to, literally, cook them. As the temperature moves higher, past around 38C, the bacteria slow down their consumption of lactose. By the time we get to 44C, no more acid is being created and, at around 50C+, the bacteria die – obviously meaning they can’t resume acid formation once the temperature reduces again.
In the advanced articles, we’ll be taking a very close look at acid measurement and control during cheese making.
Finally, let’s consider washing our curds. Washed curd cheeses, like Edam and Gouda are made by removing the some of the whey from around the curds (after scalding) and replacing it with fresh water at an appropriate temperature. This literally washes away some of the lactic acid from the curds and creates a sweeter finished product with a smoother texture and milder flavour. Perhaps unexpectedly, it also drains lactose (milk sugar) from the curds, limiting the food supply for the bacteria and consequently reducing the amount of acid that can be produced.
Washing the curds is often done in stages, i.e. your recipe will call for an amount of the whey to be removed and replaced with warm or hot water for a few minutes, before more is removed and replaced. This may take place in a number of stages, until a certain temperature (and/or pH) level is met.
At this stage, we’re ready to move on to draining, shaping and pressing curds. So, to recap this and the cutting the curds article:
The big lesson to take from these two articles is that consistency – as much as you can achieve in your kitchen – is one of the big secrets to success in cheese making.
If you’ve not read Part One of this article, then go to Cutting Cheese Curds Properly now.