14Dairy and cheese

Milk is one of the oldest foods people eat, and a long list of other foods is made from it. A kitchen uses it fresh, skimmed, condensed or dried, and turns it into cream, buttermilk, sour cream, yogurt and cheese.

Fresh dairy foods spoil if they are left at room temperature. Milk is an animal food, so it counts as a potentially hazardous food, and dairy has its own storage rules.

14.1 Milk and what is made from it

Milk recipes → Condensed and evaporated milk recipes →

Why kitchens buy milk in different forms

Fresh milk is heavy and bulky. It goes off quickly and must be kept in a fridge, which costs money. For these reasons it is a fairly expensive ingredient, and most bakeries today use dried skim milk or buttermilk powder instead.

Milk is named by how much fat it holds. Each of these grades has more than 8.25% milk solids:

Fat grades of milk.

Homogenized and pasteurized

Pasteurization heats milk to kill harmful bacteria, including those that can carry tuberculosis and fever from cows to people. The French chemist Louis Pasteur developed it in 1859. In one method, milk is heated above 71°C (160°F), held there for a set time, and then cooled straight away to 10°C (50°F) or colder.

Three heat treatments are in use today:

• HTST (high temperature, short time, also called "flash"): 72°C (161°F), held for 15 seconds. When a carton just says "pasteurized", this is usually the method used.
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• HHST (higher heat, shorter time): continuous heat, usually above 100°C (212°F). It gives products a longer life in the fridge, sold as ESL, which stands for extended shelf life.
• UHT (ultra-high temperature): 140°C (284°F) for four seconds. The milk is sprayed into a chamber of hot steam under pressure, cooled at once in a vacuum, and sealed in a sterile, airtight pack. UHT milk is sterilized, not just pasteurized, and can sit for several months with no fridge.
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Cream

Cream is sold by how much milk fat it holds. The names below are the ones used in Canada.

Cream types in Canada.

Names change from place to place, so read a recipe's origin. What the United States calls light cream, Canada mostly calls half-and-half; in Canada, "light cream" means a low-fat cream. You can make it by mixing milk with half-and-half. Quebec sells a country cream with 15% fat, and 18% cream can stand in for it. British recipes may ask for double cream, at about 48% fat, which is hard to find in Canada; use whipping or heavy cream.

Other figures for whipping cream are slightly different: 30–36% fat for light whipping cream and 36–40% for heavy.

Whipping cream whips well and can be piped. Cooks use it for custards, cream fillings and sweets. The fat level matters: with much less fat than about 32%, cream will not whip at all. It whips best when cold and when it is 48 to 60 hours old. You can add sugar, a flavor and a stabilizer as you whip. Check the carton first. Some creams already contain an agent such as carrageenan, and then no more stabilizer may be needed.

Cultured milk and cream

Buttermilk can be made in two ways. One way is to churn cream into butter and keep the liquid that is left over; this is where the name comes from. Today most buttermilk is made the other way, by adding a culture to milk to sour it. Cultured buttermilk has 0–1% fat. Buttermilk is more acidic than milk: its pH is 4.6, where milk's is 6.6. In baking, that acid reacts with baking soda to make carbon dioxide gas, which makes the batter rise.

Sour cream is cream soured with lactic acid. The acid sets the cream's proteins into a soft gel. Makers may add gums and starches to make it thicker and to stop the watery whey from separating out. Bakers put it in pastry doughs, coffee cakes and cheesecakes. Low-fat sour cream, at about 7–10% fat, usually works in baking too, though it is wetter and tastes less rich.

Figures for the fat in regular sour cream differ. One puts it at 5.5% to 14%. Another puts it at 18–20%.

Crème fraîche (French for "fresh cream") is a soured cream with 30–45% fat and a pH near 4.5. The traditional way is to leave unpasteurized milk in a pan at room temperature so the cream rises. About 12 hours later the cream is skimmed off, already thick and mildly sour from the milk's own bacteria. To make a substitute, stir a little cultured buttermilk or sour cream into whipping cream, leave it somewhere warm for at least 10 hours, then refrigerate it.

Dried and canned milk

Milk powder is made from whole milk, skim milk, buttermilk or whey. Each is pasteurized, concentrated in an evaporator, and then dried by spraying or on rollers. Each powder has limits it must meet:

• Whole milk powder: at least 95% milk solids, no more than 5% moisture, and at least 2.6% milk fat. It may also contain added vitamins A and D, and up to 0.5% lecithin, an emulsifier.
• Skim milk powder, also called non-fat dry milk: at least 95% milk solids, no more than 4% moisture and 1.5% fat.
• Buttermilk powder: at least 95% milk solids, no more than 3% moisture and 6% fat.
• Whey powder: mostly milk sugar, whey proteins, minerals and vitamins. It keeps about half the nutrients of the milk it came from.

To turn powder back into liquid milk, put the water in first and whisk the powder in straight away. If you wait, or pour water onto the powder, it tends to clump. Use water at about 21°C (70°F).

Reconstituting milk powder.

Evaporated milk, sometimes called concentrated milk, can be made from whole, partly skimmed or skim milk. About 60% of the water is taken out by evaporation. The milk is then homogenized, cooled, adjusted, canned, and sterilized in the can for 10 to 15 minutes at 99–120°C (210–248°F). It is darker than fresh milk, because at high heat the milk's protein and its sugar brown together. Small amounts of disodium phosphate or sodium citrate keep the milk from curdling during heating and storage. In Canada it must hold 7.5% milk fat and 25% milk solids.

Sweetened condensed milk is milk condensed to a third of its volume, with sugar added. It is thick and sweet. It holds about 40% sugar, at least 8.5% milk fat and at least 28% milk solids. Other figures give it 44% added sugar and more than 28.5% milk solids.

Lactose, the sugar in milk

Lactose is the natural sugar of milk. It tastes much less sweet than ordinary sugar (sucrose), and yeast cannot ferment it. So bread dough made with skim milk powder needs some added sugar, or it will ferment very slowly. Lactose does brown easily in the oven, which gives bread made with milk a darker crust. Bakers use 2–8% skim milk powder by flour weight in yeast doughs and up to 15% in cakes.

Lactose is also sold on its own, dried or as crystals. It is useful in baking in several ways:

• It brings color and texture without making food too sweet.
• It can take the place of up to half the sucrose in a recipe, or all of it in pie pastry.
• In pie crusts it gives good color, a more tender crust and less sogginess.
• In cakes and muffins it adds body and volume.
• It holds on to flavors that would otherwise escape, so food tastes stronger.

Milk, heat and acid

Milk holds two kinds of protein, casein and whey protein. Acid or the enzyme rennin makes milk curdle: it separates into solid curd and liquid whey. That is how cheese begins. How rennin and acid set milk proteins is explained with the other proteins. see chapter 7: Milk and soy

The isoelectric point of casein is pH 4.6. Milk itself sits at pH 6.6. Tomato juice is an acid food. Combine it with milk three ways: both cold, hot juice into hot milk, and hot milk into hot juice. Look at each mix at once and again after 15 minutes.

For cream of tomato soup, heat the tomato juice and the white sauce separately. Then stir the hot juice slowly into the hot sauce, and serve the soup at once. A good result is smooth, with no curdling, lumps or skin.

Storing milk and cream

Dairy is kept in the fridge at 2–4°C (36–39°F). A few rules keep it in good condition:

• Its fat soaks up strong smells, so keep it covered and in its own area.
• A fridge just for dairy is better than sharing the vegetable cooler.
• Rotate stock when new dairy arrives.
• Order it close to when you will use it, ideally every day.

Dairy that is going off turns darker and smells sour. The danger zone and the general rules for the fridge are set out with the rest of food safety. see chapter 2: The danger zone

14.2 Yogurt

Yogurt recipes → Labneh recipes →

Yogurt is made from pasteurized milk and lactic bacteria. As the bacteria grow, they make lactic acid. Once there is enough acid, the milk sets into a thick or semi-solid food.

It comes sweetened or plain. Yogurt adds both flavor and texture to many recipes. Bakers use it in cream cakes flavored with yogurt, in desserts and in frozen sweets.

Yogurt is a dairy product and is stored like one. Dairy is kept at 2–4°C (36–39°F), covered, in its own area of the fridge, and rotated as new stock comes in.

14.3 Cheese: kinds and how it is made

Dairy recipes →

What cheese is

Cheese is milk made solid and concentrated. Strictly, it is "the fresh or matured product obtained by draining the whey after coagulation of casein."

Making it takes four steps:

• Curdle the milk, with the enzyme rennet or with lactic acid.
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• Drain away the liquid whey from the firm curd.
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• Press the curd, which gives the cheese its shape.
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• Ripen it. Over time a rind forms and the flavor develops.
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How rennet and acid set milk is explained with the other proteins. see chapter 7: Milk and soy

How the curd was set helps tell cheeses apart. Cottage cheese and cream cheese are set with acid. Provolone has a stretched curd.

Kinds of cheese

With some exceptions, cheese falls into five broad groups:

• Fresh: very moist and not ripened at all. Examples: ricotta, quark, cottage cheese, cream cheese and baker's cheese.
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• Soft: usually some rind around a soft inside. Example: feta.
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• Semi-soft: not ripened, with moisture that varies. Example: mozzarella.
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• Firm: well ripened, fairly low in moisture and fairly high in fat. Examples: Swiss cheese, cheddar and brick.
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• Hard: aged a long time, with very little moisture. Example: Parmesan.
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Cheese can also be grouped by texture and by how long it ripens, and then some cheeses land in a different group. Feta goes with the semisoft ripened cheeses, and mozzarella with the firm unripened ones.

Cheese grouped by texture and ripening.

A few cheeses in that list have traits of their own:

• Cheddar is ripened by bacteria and holds about 33% fat and 37% moisture.
• Swiss cheese is ripened by bacteria that make gas.
• Provolone has a stretched curd and is smoked.
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• Parmesan and Romano are so hard and grainy that they must be grated.
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• Roquefort is a blue cheese made from ewes' milk in Roquefort, France.
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Fresh cheeses

The cheeses bakers are most likely to use are fresh ones. Each is made in its own way:

• Cottage cheese, dry curd: an acid cheese, soft and not ripened. Lactic-acid bacteria and rennet go into pasteurized skim milk. When it clots, it is cut into cubes and gently cooked until the curds firm up. The whey is drained, and the curd is rinsed and chilled in cold water.
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• Creamed cottage cheese: dry curd mixed with a cream dressing. The dressing sets the fat level: 4% for regular, or 1–2% for low fat.
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• Baker's cheese: made like dry curd cottage cheese up to the cutting of the curd, but never cooked. The curd drains in cloth bags or goes through a machine called a curd concentrator. It has about 4% fat.
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• Quark (or quarg): like baker's cheese, but soured with lactic-acid bacteria and blended with cream into a smooth spread of about 7% fat. Low-fat kinds exist, and rich ones go up to 18%. It is mild and smooth, and can often replace sour cream, cottage cheese or ricotta.
• Cream cheese: a soft, unripened, acid cheese. A mix of milk and cream is homogenized and pasteurized. Once it has cooled to about 27°C (80°F), lactic-acid bacteria go in. The curd is stirred smooth rather than cut, held at about 50°C (122°F) for an hour, then drained. Regular cream cheese is quite rich, but lighter kinds are sold.
• Ricotta: milk or whey heated with an acid until curds form, then strained. Cooks once used lemon juice or vinegar; factories now use a bacterial culture. It goes into both sweet and savory dishes.
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• Mascarpone: made like ricotta, but from cream. The cream is soured, often with tartaric acid, and heated to 85°C (185°F) until curds fall out. No starter culture or rennet is used. It is lightly salted and usually whipped. Rich and smooth, it can replace cream or butter, and is used mostly in desserts. Tiramisu, the Italian dessert, is its best-known use.

In baking, fresh cheeses fill pastries and coffee cakes, go into fried pastries such as cannoli, and make cheesecakes, sometimes mixed with richer cream cheese. For these jobs one fresh cheese can mostly stand in for another. Strain a coarse one first if needed. Firmer cheeses go into cheese bread, quiche, pizza and cheese straws.

Process cheese and cheese spreads

Process cheese is made by heating and stirring together one or more cheeses, of one kind or several, then blending in an emulsifier. A little acid, cream, water, spice or flavoring may go in too. Process cheddar has no more than 40% moisture and at least 32% fat. American process cheese is one example.

• Cheese food is made the same way, but milk, skim milk, whey or their concentrates may be added. It has no more than 44% moisture and at least 23% fat.
• Process cheese spread is like cheese food but may hold stabilizers, more water and less fat. It must spread at 70°F. Process cheddar spread has 44–60% moisture and at least 20% fat.
• Products that meet none of these standards may be labeled "imitation cheese" or "cheese products".

A cheese labeled "reduced fat" must have at least 25% less fat than the standard for that cheese.

Storing cheese

Mold grows on cheese kept somewhere warm, dark and a little damp. It shows as a bluish-green, hairy growth. Cheese that is spoiling also turns darker and smells sour. Dairy is kept at 2–4°C (36–39°F), covered and away from strong smells, and pastries filled with cheese or cream count as potentially hazardous foods.

14.4 Cooking with cheese

Dairy recipes →

Then judge four things:

• how much fat separates out;
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• the flavor;
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• how tender the cheese stays;
• how stringy it gets.

The tests change three things:

• how ripe or aged the cheese is (mild against sharp);
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• whether the cheese has been processed;
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• how hot it gets, and for how long.
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Cheese in a sauce

To make a cheese sauce, the cheese goes into a white sauce that has already thickened. Use 56 g (2 oz), about half a cup, of shredded cheese for each cup of thin white sauce. Compare sauces at 45°C, at 75°C and at a boil. After the cheese goes in, bring the sauce back to the same temperature, stirring often.

Macaroni and cheese shows the order of work:

• Bring the white sauce to a full boil, then take it off the heat.
• Wait 45 seconds before you blend in the cheese.
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• Stir in the cooked macaroni and top it with buttered crumbs.
• Set the dish on a rack in a pan of hot water, and bake it uncovered at 350°F for 30 minutes.
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Cheese under dry heat

A grilled cheese sandwich is a simple test of dry heat.

• Butter one side of each of two slices of bread, and put the cheese between the unbuttered sides.
• Heat a tablespoon of butter in a frying pan over medium-low heat.
• Press the sandwich lightly and cook it for 3 to 5 minutes until the bottom is golden.
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• Turn it and cook 3 to 5 minutes more, until the second side browns and the cheese has melted.

Pan-frying itself is taught with the other dry-heat methods. see chapter 8: How much fat

Open cheese toasts show how oven heat and time change cheese. Bake slices of each cheddar on bread at 300°F until just melted, then leave some in for 10 more minutes. Repeat the test at 500°F, this time leaving some in until the cheese is brown and bubbling. Taste each one as soon as it comes out.