The same basic steps are involved in the production of all most all cheeses. With few exceptions, milk is cultured, coagulated, moulded, salted, and ripened.
Like anything else, cheese is better appreciated when fully understood. We've compiled this little course, cheese making 101, to better help you understand how milk turns into cheese and, just as importantly, how slight changes at each step of the way create very different types of cheese by the end of the process.
And, of course, we invite you to come visit our farm and see the cheese making process first hand.
What is it that makes cheese cheese? Go to the dictionary and you will find that cheese is a "fermented milk product" - which is not particularly enlightening.
Let's take a slightly more detailed look at how cheese is made. First, it is clear that cheese must be made from milk; it doesn't matter what milk - in theory the milk of any mammal will do, but in practice it almost always means the milk of a cow, sheep, goat or water buffalo.
The second requirement is that the milk be fermented. We normally think of fermentation as a wine-making process, or as something that happens to things that have been in the back of the refrigerator for too long - and in fact both of these are examples of fermentation. Fermentation is any process that involves the conversion of sugars into acid and gas. In cheese making the sugar involved is lactose, a form of sugar which occurs in all milks and accounts for 4% to 5% of the makeup of milk.
The actual organisms doing the fermenting in cheese making belong to a group of bacteria called "lacto-bacilli", which simply means milk bacteria, and are more generally referred to as a dairy culture. A very simple example of these bacteria at work is in yogurt: anyone who has made yogurt at home knows that by adding a "culture" (which can be a spoonful of store-bought yogurt) to warm milk, and then incubating the milk (keeping it warm) for several hours is all that is needed to make yogurt, and the flavour will change from the sweet taste of fresh milk to the acid tang of yogurt.
Yogurt, even if we don't think of it that way, meets the definition of "cheese". But most cheeses require extra steps than merely culturing and incubation. Below you will find the extra processes which we use to produce our cheeses (but bear in mind that not all the cheeses use all the steps).
Pasteurisation is the first step in almost all modern cheese making, but it is not actually necessary from a cheese making standpoint at all. It is a method of heat treatment invented by Louis Pasteur in the late 1800's to prevent the spread of diseases carried by milk and other foods, and involves either heating the milk to 63 degrees Celsius and holding it there for 30 minutes or heating milk to 72 degrees for 18 seconds. This level of heating has been determined to kill any harmful bacteria that may be in the raw milk. Of course, it also kills any beneficial bacteria, such as naturally occurring lacto-bacilli, but it is simple enough to add these back into the milk once it has been cooled, so this side-effect is not really a problem (although some would argue that the wide variety of culture strains present in the raw milk cannot easily be reproduced). Even if milk is not pasteurised, it still needs to have a culture introduced into it, and when raw milk cheeses are made, it is this that is the first step.
The other drawback of pasteurisation (other than the loss of the original bacteria) is that it breaks up some of the fat molecules in the milk, and this alters the taste of the cheese. Goat milk cheeses especially get a stronger "tangy" taste. However, this is only a problem for cheese that has been pasteurised using the faster method, and this is one of the primary reasons for our choice always to pasteurise our milk with the slower and cooler method.
The law in British Columbia, and most of Canada, requires all cheese to be made from pasteurised milk, unless the finished cheese will be stored, before sale, for longer than 60 days at a temperature above 4 degrees Celsius. This is normal for hard cheeses, so it is possible to find this type of cheese made from raw milk in Canada, but they are usually pasteurised too. A soft or semisoft cheese cannot be kept for this long, with the result that just about all cheeses made in Canada are pasteurised. All of the cheeses made by Salt Spring Island Cheese are always made with pasteurized milk, regardless of whether they meet the criteria which would allow them to be made out of raw milk.
Culturing and Transferring:
Culturing happens once the milk has been cooled below 35 degrees Celsius; it is the process of stirring the dairy bacteria into the milk, to start the process of fermentation. (Even raw milk cheeses are cultured.)
This is followed by a short period, during which the culture is allowed to become active and begin to produce lactic acid. This period can be very short for Camembert-type cheeses and for many hard and semi-hard cheeses, but it is considerably longer for fresh cheeses, where it is desirable to allow the milk to become quite acidic before it is scooped into the moulds.
Transferring is simply the process of moving the milk from the pasteurizer to the cheesemaking vat. With most cheeses, this takes place as soon as the milk is cooled and cultured, but because of the longer time that the active culture works in the milk for our fresh cheeses, this milk does not get transferred to the cheese vats until the following day.
Coagulation consists of adding an enzyme to the milk which changes it structure from a liquid into a (very loose) solid. You may remember the nursery rhyme about Little Miss Muffet sitting on a tuffet eating her curds and whey. What her mother had done was to add rennet to milk and let it sit. After about an hour a delicate curd forms, similar to yogurt, but looser. Under the name of junket, this is still eaten (by some) in England as a dessert -- usually flavoured and with sugar added.
Rennet is an enzyme produced in the fourth stomach (abomassum) of a young ruminant (cow, sheep, goat, deer, etc.), which coagulates the milk it takes from its mother in order to better digest it. Legend has it that cheese making got its start when one of our distant ancestors tried to store milk in a skin bag made from such an animal's stomach, and found that the milk had turned into something quite different. Non-animal alternatives to rennet are available, often derived from plants such as artichokes and cardoons.
At Salt Spring Cheese, we have tried for years to find a vegetable substitute for rennet that does not leave a bitter aftertaste in the cheese, but so far without success. This is a well known problem for all cheese made with alternatives to rennet, but we have found the bitter taste is especially pronounced with goat milk cheeses.
The next step is cutting the curd (once it has set) with a knife or set of parallel blades into cubes ranging, depending on the cheese, from 3 cm down to the size of a grain of rice -- the smaller the cut, the firmer the cheese will be. This is followed by a period of healing, during which the cubes of curd shrink slightly and expel whey through the cut surfaces. This takes 20 to 30 minutes. Then the curd is stirred gently, by hand with a large ladle, to further expel whey and firm up the curd.
How long to stir before ladling the curds into the moulds is one of the key questions in the making of a cheese, and it is largely a question of feel. If the stirring is too short, or not vigorous enough, too much whey will be left in the curds. This has the counter-intuitive result of producing a cheese that is acid-tasting, dry and crumbly - particularly in a hard cheese or a semi-hard one like Montaña. The whey trapped inside the curds provides more food for the acid producing bacteria, which can then go on working longer, and cause the body of the cheese to become more acid. This in turn affects the texture, because acidity is closely tied to calcium content: the more acid in the cheese, the more calcium leaches out of it, and the less elastic the cheese becomes. On the other side, the consequence of stirring too long or too vigorously is a lack of flavour and a rubbery texture.
Moulding takes place once the curds reach the desired firmness; it is simply the process of scooping the curds into the moulds, which will determine the size and shape of the finished cheeses.
Almost all cheeses are moulded after they have gone through the cutting, healing and stirring stages mentioned above. However there are some cheeses which bypass these steps, and go directly from renneting to moulding. Traditional Camembert is one cheese where the set curd is ladled directly into the moulds, and their labels will often carry the words "Moule a la louche" to indicate this.
The other category of cheese where curd is traditionally scooped into the moulds without cutting or stirring is soft fresh cheeses, such as our fresh goat cheese. The difference between these two cheeses - traditional Camembert and soft fresh - is that while the Camembert is moulded shortly after the curd has set, with the soft fresh there is a longer fermentation period during which the acidity of the curd increases, and it is not scooped into the moulds until it has reached a degree of acidity greater than that found in any other cheese.
By the time it is ready to be scooped, the soft cheese has become very acidic indeed and has lost most of its calcium, which results in a very fragile curd. Stirring this curd would simply turn it into a slurry that would run out through the holes in the moulds. To avoid this it is scooped directly into the moulds with a scoop that looks like a stainless steel dust-pan. In this way we are able to transfer very fragile curd into the moulds without breaking it up.
The next step is to allow the cheese to drain excess whey. However small a curd may be cut, and however much it is stirred, there will still be some whey left in the curds after moulding which it is desirable to drain. There are holes in the moulds to allow this draining to take place. Draining usually takes place under the weight of the cheese itself, but sometimes a cheese may be pressed mechanically to encourage additional drainage (although we do not do this). Draining usually takes between 24 and 72 hours. At the end of it, the cheeses will be noticeably smaller, firmer, and in their final shapes. To make sure that the cheeses have an even shape, they are turned in their moulds several times during this process.
Salting is the last essential step in the cheese making process. While a cheese is still a cheese without salt, very few cheeses are made without it. This is mostly for flavour reasons - saltless cheese tastes very bland to our salt-attuned taste buds. However there are some cheeses which need the salt to encourage mould growth, and this is particularly true if they use blue moulds. It is one of the reasons why some blue cheeses can taste as if they have been over salted. It is also possible to add salt to milk before it is made into cheese, but since salt is hydroscopic, doing this increases the moisture content of the cheese, so we salt our cheeses after the whey has drained from them (which is the traditional time to salt cheese), as it gives the cheese a richer taste and texture.
Salting is done either with a dry salt or by immersing the cheese in a brine bath. (Soft cheeses must be dry salted as they would fall apart in brine.) Beyond that, it usually depends on the preference of the cheese maker; in our case all of our cheeses, apart from the fresh, are brined.
The last, and in many ways the least understood, step in making cheese is ripening. However, fresh cheeses are ready to be eaten without any ripening. They have a quality of freshness that is hard to beat just as they are. Try them unpackaged straight from us on Saltspring Island if you can. It has a freshness to it that cannot be replicated any other way, but it must be eaten as soon as possible, and no longer than a week after it is made.
To keep fresh cheeses beyond this, they need to be packaged or protected from the air in some other way. Our answer to preserving freshness in the soft cheese is to vacuum-pack it: once all the air is removed, almost no bacterial activity can take place and the cheese changes very little over its two month shelf life, provided that it is kept refrigerated.
All of the steps above normally only take a few days, and most cheeses look very much the same after the above steps. It is what happens during the 'ripening' process where the difference start to appear, though the groundwork for most of these differences is laid during the first steps of a cheese's life. Almost all ripening takes place in a cool and humid environment, the idea being to prevent the cheese from drying out while keeping it warm enough to allow the breakdown of its fats and proteins.
The main categories of ripened cheeses are:
Surface ripened cheeses are broken into two kinds: bloomy rind and washed-rind cheeses. With bloomy rind cheeses like Brie and Camembert, the penicillin mould that grows on the outside of the cheese acts as the ripening agent. Ripening takes place from the outside in, which is why you can often detect a difference in texture between the centre of the cheese (the least ripe part) and the smoother and creamier outer part just beneath the rind. Ideally though, the whole thing should be consistently ripened, which is a question of matching the time that the cheese is ripened, with the thickness of the cheese to begin with.
The second kind of surface ripened cheese is a washed-rind (or smear-ripened) cheese, like Epoisses, Oka and Limburger. These are typically the very strong smelling cheeses that are hard to hide in your luggage and avoid detection by customs officials. However the flavour of this type of cheese is generally much less powerful than its aroma, particularly if you cut off the outer rind. As the name implies, these cheeses are rubbed during ripening with some kind of liquid, which can be anything from salt and water to wines and spirits flavoured with herbs and spices. The characteristic orange colour (and powerful aroma) of these cheeses comes from the addition to the washing liquid of a bacterium called Brevibacterium linens (often called simply B. Linens).
Natural rind cheeses are those cheeses in which the outside of the cheese has simply been allowed to dry out and form a crust. Included in this group are Parmesan (Parmigiano-Reggiano), Gruyere, tomme de Savoie, Stilton, and many, many others. During ripening, the rinds of these cheeses are brushed to remove the grayish moulds which typically grow on the outside of the rind (or, in the case of Parmesan, rubbed with oil).
Waxed cheeses, including Gouda and some Cheddars, are so treated to protect against mould growth on the outside of the cheese. Other forms of protection include silver foil (Roquefort and several other blue cheeses), cheesecloth (traditional Cheddars) and vacuum bagging (used for some modern cheeses, particularly where there is a shortage of ripening space). These cheeses also tend to be softer than their natural rind sisters, as their coatings keep more moisture in them.
Brine ripening, of which feta is far and away the best known example, is actually a misnomer. The original purpose of immersing the cheese in brine (a salt and water solution) was to preserve its freshness. Feta may be aged in brine, but it is not being ripened in the normal sense because of the absence of air.