SOLID CULTURED DAIRY PRODUCTS

Cheese• A food consisting of the coagulated, compressed, and

usually ripened curd of milk separated from whey• The curd of milk separated from whey, often seasoned

and aged• A food derived from milk curd produced in a wide range

of flavors, textures, and forms by the coagulation of the milk protein casein

Etymology

The word CHEESE comes from the Latin term caseus, from which the modern word casein is also derived. However, the earliest source is from the proto-Indo-European root kwat-, which means "to ferment, to become sour".

Types of Cheese

1. Fresh Requires high acidity by bacterial action

E.g., Cottage cheese, Cream cheese

2. Soft Requires slow acid development, washing to control lactose and minimal cooking time

E.g., Brie, Camembert, Mozzarella and Gouda

3. Hard Requires high acid development and high temperature

E.g., Cheddar, Parmesan, and EdamCheddar

Steps in Cheese Production

1. Curdling• Milk Preparation

• Acidification• Coagulation

2. Curd Processing• Draining• Salting• Molding

Others: Stretching, Cheddaring, Washing

3. Ripening

Other Curd Processing Techniques• Stretching (Mozzarella, Provolone) The curd is

stretched and kneaded in hot water, developing a stringy, fibrous body.

• Cheddaring (Cheddar, other English cheeses) The cut curd is repeatedly piled up, expelling more water. The curd is also mixed (or milled) for a long time, taking the sharp edges off the cut curd pieces and influencing the final product's texture.

• Washing (Edam, Gouda, Colby) The curd is washed in warm water, lowering its acidity and making for a milder-tasting cheese.

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CURDLING1. Milk Preparation•Heat treatment, filtration, and standardization

2. Acidification•Addition of starter cultures

E.g., Streptococcus spp. for cheddar, Gouda and cottage cheese. Lactobacillus spp. (L. bulgaricus and L. acidophilus) for Swiss and Grana cheeses.

•These microorganisms will ferment the carbohydrates present in milk into lactic acid•NOTE: pH should be reduced to about 4.7, the optimum for milk coagulation.11/07/14

CURDLING3. Coagulation•Involves the action of rennet (rennin or chymosin) on casein micelles in milk•Rennet is a stomach extract of young unweaned calves that contains chymosin •Chymosin coagulates milk optimally at pHs 6.0-6.4 at 20-30°C, although its optimum pH is ca. 4 •The optimum temperature for coagulation is ca. 40°C, but milk for cheesemaking is coagulated with rennet at 31-32°C because, at this temperature, the curd is rheologically most suitable for cheesemaking.

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A white, tasteless, odorless protein precipitated from milk by rennin•Present as macromolecular aggregates or micelles •Responsible for the white color of milk, which is due to the light reflected by the micelles•It makes milk a colloidal dispersion

CASEIN

• Comprises 45–50% α-casein, 25–35% β-casein, 8–15% κ-casein, and 3–7% γ-casein.

• Each casein fraction differs in sensitivity to calcium, solubility, amino acid makeup and electrophoretic mobility.

• κ-Casein Soluble in calcium solutions, which would normally precipitate other casein fractions. Important in stabilizing casein micelles

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NOTES ON CASEIN

CASEIN STRUCTURE

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κ-casein Other casein

Milk Coagulation by ChymosinIntroducing chymosin to milk in cheesemaking, normally at about 32°C, destabilizes the casein micelle in a two-step reaction:

1. Primary (enzymatic) phase

2. Secondary (nonenzymatic) phase

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Chymosin cleaves the phenylalanine-methionine bond (105-106) of κ-casein, thus eliminating its stabilizing action on calcium-sensitive α- and β-caseins.

PRIMARY PHASE

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The micelles without intact κ-casein aggregate in the presence of ionic calcium in milk and form a gel (curd).

SECONDARY PHASE

Ca2+

Ca2+ Ca2+

Ca2+

Ca2+ Ca2+

Ca2+

Ca2+

Ca2+

Ca2+

CURD PROCESSING1. Draining•Cutting of curd into small cubes to allow water to drain from individual pieces of curd.•Expulsion of whey results in shrinkage accompanied by further degradation of κ-casein, which may lead to the formation of new crosslinks in the rennet gel or curd and the development of a firmer or more rubbery curd.

2. Salting•Influences flavor, moisture and texture•Salting also causes the removal of whey and slows down the rate of acid development as well as inhibits growth of undesirable bacteria

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CURD PROCESSING3. Molding or Shaping•Most cheeses achieve their final shape when the curds are pressed into a mold. •During molding, the curd is comminuted and shaped in a mold using a hydraulic press.•The harder the cheese, the more pressure is applied. •The pressure drives out moisture --- the molds are designed to allow water to escape --- and unifies the curds into a single solid body.

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RIPENING• A newborn cheese is usually salty yet bland in flavor

and, for harder varieties, rubbery in texture. Therefore, most cheeses are ripened under controlled conditions to develop the required texture and flavor.

• Ripening (affinage) is the ageing and maturing of cheese.

• Lasts from a few days to several years• As a cheese ages, microbes and enzymes transform

texture and intensify flavor. This transformation is largely a result of the breakdown of casein proteins and milk fat into a complex mix of amino acids, amines, and fatty acids.

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CHEDDAR CHEESEA relatively hard, pale yellow-to-off white (unless artificially colored) sometimes “sharp”tasting natural cheese

• Close and firm in texture, yet mellow in character or quality; it is rich with a tendency to melt in the mouth, the flavor full and fine, approaching that of hazelnut” --- Joseph Harding

• Originated from the English village of Cheddar in Sommerset

• Most popular cheese in the UK, second in the US

CHEDDAR PRODUCTION PROCESS1. Curd and whey separation using rennet.

2. Cheddaring. The curd, after heating, is kneaded with salt, cut into cubes to drain the whey and then stacked and turned.

3. Ripening for up to 15 months. The cheese is kept at a constant temperature often requiring special facilities.

NOTE: Caves provide an ideal environment for maturing cheese.

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CHEDDAR PACKAGINGCheddar cheese used to be packaged in black wax, which then changed to larded cloth, which is impermeable to contaminants, but still allows the cheese to breath. However, this practice is now limited to artisan cheese makers.

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… (Unopened) Fridge Freezer

Past Printed Date Past Printed Date

Hard Cheese (Parmesan, Asiago, Romano) lasts for

2-4 Months 6-8 Months

Shredded Hard Cheese lasts for

1-2 Month 6-8 Months

Semi-Hard Cheese Chunk (Cheddar, Swiss) lasts for

1-2 Months 6-8 Months

Sliced Semi-Hard Cheese lasts for

1 Month 6-8 Months

(Opened) Refrigerator Freezer

Hard Cheese Chunk (Parmesan, Asiago, Romano) lasts for

3-6 Weeks 6-8 Months

Shredded Hard Cheese lasts for

3-4 Weeks 6-8 Months

Semi-Hard Cheese Chunk lasts for

3-6 Weeks 6-8 Months

Sliced Semi-Hard Cheese lasts for

2 Weeks 6-8 Months

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The shelf life of hard cheese  is influenced by a variety of factors, such as the type of cheese, the processing method and packaging date, its exposure to heat, how the cheese is stored and the best by date or sell by date. So how long does cheese last?  When properly stored at or below 40°  F, the shelf life of cheese is as follows:

Shelf Life of Cheese

Which types of cheese can be frozen?

Does Cheese Freeze Thawed ResultDoes Cream Cheese Freeze

Not well Chunky and Watery

Does Ricotta Cheese Freeze

Not WellRunny – Separated and Watery

Does Brie Cheese Freeze

Yes Grainer texture

Does Cheddar Cheese Freeze

Yes Crumblier

Does Mozzarella Cheese Freeze

Yes Rubbery & Yellow

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Facts about cheese freezing

• The firmer the cheese, the longer its shelf life. It’s the same with cheese quality after freezing.The best cheese to freeze is shredded firm cheese. Firmer cheeses freeze better, especially if they are shredded. Blocks of cheese also freeze well, but they tend to crumble instead of slicing nicely after thawing.

• Softer cheeses do not freeze well because the moisture within the cheese forms ice crystals. When defrosted, these crystals destroy the texture of the cheese. So softer cheeses are grainy after freezing, the texture is more noticeably altered.

• *Note: Any cheese, once defrosted, is better if used for cooking than just eating plain.

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