Background
Cheese is a fermented food derived from the milk of various mammals. Since humans began to domesticate milk-producing animals around 10,000 B.C., they have known about the propensity of milk to separate into curds and whey. As milk sours, it breaks down into curds—lumps of phosphoprotein—and whey, a watery, grey fluid that contains lactose, minerals, vitamins, and traces of fat. It is the curds that are used to make cheese, and practically every culture on Earth has developed its own methods, the only major exceptions being China and the ancient Americas.
The first cheeses were “fresh”, that is, not fermented. They consisted solely of salted white curds drained of whey, similar to today’s cottage cheese. The next step was to develop ways of accelerating the natural separation process. This was achieved by adding rennet to the milk. Rennet is an enzyme from the stomachs of young ruminants—a ruminant is an animal that chews its food very thoroughly and possesses a complex digestive system with three or four stomach chambers; in the United States, cows are the best-known creatures of this kind. Rennet remains the most popular way of “starting” cheese, though other starting agents such as lactic acid and various plant extracts are also used.
By A.D. 100, cheesemakers in various countries knew how to press, ripen, and cure fresh cheeses, thereby creating a product that could be stored for long periods. Each country or region developed different types of cheese that reflected local ingredients and conditions. The number of cheeses thus developed is staggering. France, famous for the quality and variety of its cheeses, is home to about 400 commercially available cheeses.
The next significant step to affect the manufacture of cheese occurred in the 1860s when Louis Pasteur introduced the process that bears his name. Pasteurisation entails heating milk to partially sterilise it without altering its basic chemical structure. Because the process destroys dangerous microorganisms, pasteurised milk is considered more healthful, and most cheese is made from pasteurised milk today.
The first and simplest way of extending the length of time cheese would keep without spoiling was simply ageing it. Aged cheese was popular from the start because it kept well for domestic use. In the 1300s, the Dutch began to seal cheese intended for export in hard rinds to maintain freshness and, in the early 1800s, the Swiss became the first to process cheese. Frustrated by the speed with which their cheese went bad in the days before refrigeration, they developed a method of grinding old cheese, adding filler ingredients, and heating the mixture to produce a sterile, uniform, long-lasting product. Another advantage of processing cheese was that it permitted makers to recycle edible, second-grade cheeses in a palatable form.
Before the twentieth century, most people considered cheese a speciality food, produced in individual households and eaten rarely. However, with the advent of mass production, both the supply of and the demand for cheese increased. In 1955, 13 per cent of milk was made into cheese. By 1984, this percentage had grown to 31 per cent, and it continues to increase. Interestingly, though processed cheese is now widely available, it represents only one-third of the cheese being made today. Even though most cheeses are produced in large factories, a majority are still made using natural methods. In fact, small, “farmhouse” cheesemaking has made a comeback in recent years. Many Americans now own small cheese-making businesses, and their products have become popular, particularly among connoisseurs.
Raw Materials
Cheese is made from milk, and that milk comes from animals as diverse as cows, sheep, goats, horses, camels, water buffalo, and reindeer. Most cheesemakers expedite the curdling process with rennet, lactic acid, or plant extracts, such as the vegetable rennet produced from wild artichokes, fig leaves, safflower, or melon.
In addition to milk and curdling agents, cheeses may contain various ingredients added to enhance flavour and colour. The great cheeses of the world may acquire their flavour from the specific bacterial moulds with which they have been inoculated—an example being the famous Penicillium roqueforti used to make France’s Roquefort and England’s Stilton. Cheeses may also be salted or dyed, usually with annatto, an orange colouring made from the pulp of a tropical tree, or carrot juice.
They may be washed in brine or covered with ashes. Cheesemakers who wish to avoid rennet may encourage the bacterial growth necessary to curdling by several unusual methods. Some cheeses possess this bacteria because they are made from unpasteurised milk. Other cheeses, however, are reportedly made from milk in which dung or old leather has been dunked; still others acquire their bacteria from being buried in mud.
The unusual texture and flavour of processed cheese are obtained by combining several types of natural cheese and adding salt, milk fat, cream, whey, water, vegetable oil, and other fillers. Processed cheese will also have preservatives, emulsifiers, gums, gelatin, thickeners, and sweeteners as ingredients. Most processed cheese and some natural cheeses are flavoured with ingredients such as paprika, pepper, chives, onions, cumin, caraway seeds, jalapeño peppers, hazelnuts, raisins, mushrooms, sage, and bacon. Cheese can also be smoked to preserve it and give it a distinctive flavour.
The Manufacturing Process
Although cheesemaking is a linear process, it involves many factors. Numerous varieties of cheese exist because ending the simple preparation process at different points can produce different cheeses, as can varying additives or procedures. Cheesemaking has long been considered a delicate process. Attempts to duplicate the success of an old cheese factory have been known to fail because conditions at a new factory do not favour the growth of the proper bacteria.
1. Preparing the milk
Small cheese factories accept either morning milk (which is richer), evening milk, or both. Because it is generally purchased from small dairies which don’t pasteurise, this milk contains the bacteria necessary to produce lactic acid—one of the agents that trigger curdling. The cheesemakers let the milk sit until enough lactic acid has formed to begin producing the particular type of cheese they’re making. Depending on the type of cheese being produced, the cheesemakers may then heat the ripening milk. This process differs slightly at large cheese factories, which purchase pasteurised milk and must consequently add a culture of bacteria to produce lactic acid.
2. Separating the curds from the whey
The next step is to add animal or vegetable rennet to the milk, furthering its separation into curds and whey. Once formed, the curds are cut both vertically and horizontally with knives. In large factories, huge vats of curdled milk are cut vertically using sharp, multi-bladed wire knives reminiscent of oven racks. The same machine then agitates the curds and slices them horizontally. If the cutting is done manually, the curds are cut both ways using a large, two-handled knife. Soft cheeses are cut into big chunks, while hard cheeses are cut into tiny chunks (for cheddar, for instance, the space between the knives is about one-twentieth of an inch [half a centimetre]). After cutting, the curds may be heated to hasten separation, but they are more typically left alone. When separation is complete, the whey is drained.
3. Pressing the curds
Moisture must then be removed from the curds, although the amount removed depends on the type of cheese. For some types with high moisture contents, the whey-draining process removes sufficient moisture. Other types require the curds to be cut, heated, and/or filtered to eliminate excess moisture. To make cheddar cheese, for example, cheesemakers “cheddar” (finely chop) the curd. To make hard, dry cheeses such as parmesan, cheesemakers first cheddar and then cook the curd. Regardless, if the curds are to be aged, they are then put into moulds. Here, they are pressed to give the proper shape and size. Soft cheeses such as cottage cheese are not aged.
4. Ageing the cheese
At this stage, the cheese may be inoculated with a flavouring mould, bathed in brine, or wrapped in cloth or hay before being deposited in a place of the proper temperature and humidity to age. Some cheeses are aged for a month, others for up to several years. Ageing sharpens the flavour of the cheese; for example, cheddar aged more than two years is appropriately labelled extra sharp.
5. Wrapping natural cheese
Some cheeses may develop a rind naturally, as their surfaces dry. Other rinds may form from the growth of bacteria sprayed on the surface of the cheese. Still other cheeses are washed, and this process encourages bacterial growth. In place of or in addition to rinds, cheeses can be sealed in cloth or wax. For local eating, this may be all the necessary packaging. However, large quantities of cheese are packaged for sale in distant countries. Such cheeses may be heavily salted for export (such as Roquefort) or sealed in impermeable plastic or foil.
6. Making and wrapping processed cheese
Edible yet inferior cheeses can be saved and made into processed cheese. Cheeses such as Emmental (commonly called Swiss), Gruyère (similar to Swiss), Colby, or cheddar are cut up and very finely ground. After this powder has been mixed with water to form a paste, other ingredients such as salt, fillers, emulsifiers, preservatives, and flavourings are added. The mixture is then heated under controlled conditions. While still warm and soft, the cheese paste is extruded into long ribbons that are sliced. The small sheets of cheese are then placed onto a plastic or foil sheet and wrapped by machine.
Quality Control
Cheesemaking has never been an easily regulated, purely scientific process. Quality cheese has traditionally been the sign of an experienced—perhaps even lucky—cheesemaker insistent upon producing flavourful cheese. Analytical tests of cheese characteristics may yield a good cheese, but cheese making has traditionally been a chancy endeavour. Developing a single set of standards is difficult because each variety has its own range of characteristics. A cheese that strays from this range will be inferior. For example, good soft blue cheese will have high moisture and a high pH; cheddar will have neither.
One controversy in the cheese field centres on whether it is necessary to pasteurise the milk that goes into cheese. Pasteurisation was promoted because of the persistence of Mycobacterium tuberculosis, a pathogen that occurs in milk products. The United States allows cheeses that will be aged for over sixty days to be made from unpasteurised milk; however, it requires that many kinds of cheese be made from pasteurised milk. Despite these regulations, it is possible to eat cheeses made from unpasteurised milk to no ill effect. In fact, cheese connoisseurs insist that pasteurising destroys the natural bacteria necessary for quality cheese manufacture. They claim that modern cheese factories are so clean and sanitary that pasteurisation is unnecessary. So far, the result of this controversy has merely been that connoisseurs avoid pasteurised-milk cheeses.
Regulations exist so that the consumer can purchase authentic cheeses with ease. France, the pre-eminent maker of a variety of natural cheeses, began granting certain regions monopolies on the manufacture of certain cheeses. For example, a cheese labelled Roquefort is guaranteed to have been ripened in the Combalou caves, and such a guarantee has existed since 1411. Because cheese is made for human consumption, great care is taken to ensure that the raw materials are of the highest quality, and cheese intended for export must meet particularly stringent quality control standards.
Because they possess such disparate characteristics, different types of cheese are required to meet different compositional standards. Based on its moisture and fat content, a cheese is labelled soft, semi-soft, hard, or very hard. Having been assigned a category, it must then fall within the range of characteristics considered acceptable for cheeses in that category. For example, cheddar, a hard cheese, can contain no more than 39 per cent water and no less than 50 per cent fat. In addition to meeting compositional standards, cheese must also meet standards for flavour, aroma, body, texture, colour, appearance, and finish. To test a batch, inspectors core a representative wheel vertically in several places, catching the centre, the sides, and in between. The inspector then examines the cheese to detect any inconsistencies in texture, rubs it to determine body (consistency), smells it, and tastes it. Cheese is usually assigned points for each characteristic, with flavour and texture weighing more than colour and appearance.
Processed cheese is also subject to legal restrictions and standards. Processed American cheese must contain at least 90 per cent real cheese. Products labelled cheese food must be 51 per cent cheese (most are around 65 per cent). Products labelled cheese spread must also be 51 per cent cheese, the difference being that such foods have more water and gums to make them spreadable. Cheese product usually refers to a diet cheese that has more water and less cheese than American cheese, cheese food, or cheese spread, but the specific amount of cheese is not regulated. Similarly, imitation cheese is not required to contain a minimum amount of cheese, and cheese is usually not its main ingredient. In general, quality processed cheese should resemble cheese and possess a clear cheesy flavour—preferably with a “bite”, as sharp cheddar has. It should be smooth and evenly coloured, avoid rubberiness, and melt in the mouth.