| Curdling | | | | The cut curd is repeatedly piled up, pushing |
| | | | more moisture away. The curd is also mixed |
| The only strictly required step in making any | | | | (or milled) for a long period of time, taking |
| sort of cheese is separating the milk into | | | | the sharp edges off the cut curd pieces and |
| solid curds and liquid whey. Usually this is | | | | influencing the final product's texture. |
| done by acidifying the milk and adding | | | | |
| rennet. The acidification is accomplished | | | | Washing: (Edam, Gouda, Colby) The curd is |
| directly by the addition of an acid like | | | | washed in warm water, lowering its acidity |
| vinegar in a few cases (paneer, queso | | | | and making for a milder-tasting cheese. |
| fresco), but usually starter bacteria are | | | | |
| employed instead. These starter bacteria | | | | Most cheeses achieve their final shape when |
| convert milk sugars into lactic acid. The | | | | the curds are pressed into a mold or form. |
| same bacteria (and the enzymes they produce) | | | | The harder the cheese, the more pressure is |
| also play a large role in the eventual flavor | | | | applied. The pressure drives out moisture |
| of aged cheeses. Most cheeses are made with | | | | — the molds are designed to allow |
| starter bacteria from the Lactococci, | | | | water to escape — and unifies the |
| Lactobacilli, or Streptococci families. Swiss | | | | curds into a single solid body. |
| starter cultures also include Propionibacter | | | | |
| shermani, which produces carbon dioxide gas | | | | Aging |
| bubbles during aging, giving Swiss cheese or | | | | |
| Emmental its holes. | | | | A newborn cheese is usually salty yet bland |
| | | | in flavor and, for harder varieties, rubbery |
| Some fresh cheeses are curdled only by | | | | in texture. These qualities are sometimes |
| acidity, but most cheeses also use rennet. | | | | enjoyed—cheese curds are eaten on |
| Rennet sets the cheese into a strong and | | | | their own—but usually cheeses are left |
| rubbery gel compared to the fragile curds | | | | to rest under carefully controlled |
| produced by acidic coagulation alone. It also | | | | conditions. This aging period (also called |
| allows curdling at a lower | | | | ripening, or, from the French, affinage) can |
| acidity—important because | | | | last from a few days to several years. As a |
| flavor-making bacteria are inhibited in | | | | cheese ages, microbes and enzymes transform |
| high-acidity environments. In general, | | | | its texture and intensify its flavor. This |
| softer, smaller, fresher cheeses are curdled | | | | transformation is largely a result of the |
| with a greater proportion of acid to rennet | | | | breakdown of casein proteins and milkfat into |
| than harder, larger, longer-aged varieties. | | | | a complex mix of amino acids, amines, and |
| | | | fatty acids. |
| Curd processing | | | | |
| | | | Some cheeses have additional bacteria or |
| At this point, the cheese has set into a very | | | | molds intentionally introduced to them before |
| moist gel. Some soft cheeses are now | | | | or during aging. In traditional cheesemaking, |
| essentially complete: they are drained, | | | | these microbes might be already present in |
| salted, and packaged. For most of the rest, | | | | the air of the aging room; they are simply |
| the curd is cut into small cubes. This allows | | | | allowed to settle and grow on the stored |
| water to drain from the individual pieces of | | | | cheeses. More often today, prepared cultures |
| curd. | | | | are used, giving more consistent results and |
| | | | putting fewer constraints on the environment |
| Some hard cheeses are then heated to | | | | where the cheese ages. |
| temperatures in the range of | | | | |
| 35°C–55°C | | | | For the blue cheeses (Roquefort, Stilton, |
| (100°F–130°F). This forces more | | | | Gorgonzola), Penicillium mold is introduced |
| whey from the cut curd. It also changes the | | | | to the curd before molding. During aging, the |
| taste of the finished cheese, affecting both | | | | blue molds (P. roqueforti or P. glaucum ) |
| the bacterial culture and the milk chemistry. | | | | grow in the small fissures in the cheese, |
| Cheeses that are heated to the higher | | | | imparting a sharp flavor and aroma. The same |
| temperatures are usually made with | | | | molds are also grown on the surface of some |
| thermophilic starter bacteria which survive | | | | aged goat cheeses. The soft cheeses Brie and |
| this step—either lactobacilli or | | | | Camembert, among others, get a surface growth |
| streptococci. | | | | of other Penicillium species, white-colored |
| | | | P. candidum or P. camemberti. The surface |
| Salt has a number of roles in cheese besides | | | | mold contributes to the interior texture and |
| adding a salty flavor. It preserves cheese | | | | flavor of these small cheeses. |
| from spoiling, draws moisture from the curd, | | | | |
| and firms up a cheese’s texture in an | | | | Some cheeses are periodically washed in a |
| interaction with its proteins. Some cheeses | | | | saltwater brine during their ripening. Not |
| are salted from the outside with dry salt or | | | | only does the brine carry flavors into the |
| brine washes. Most cheeses have the salt | | | | cheese (it might be seasoned with spices or |
| mixed directly into the curds. | | | | wine), but the salty environment may nurture |
| | | | the growth of the Brevibacterium linens |
| A number of other techniques can be employed | | | | bacteria, which can impart a very pronounced |
| to influence the cheese's final texture and | | | | odor (Limburger) and interesting flavor. The |
| flavor. Some examples: | | | | same bacteria can also have some impact on |
| | | | cheeses that are simply ripened in humid |
| Stretching: (Mozzarella, Provolone) The curd | | | | conditions, like Camembert. Large populations |
| is stretched and kneaded in hot water, | | | | of these "smear bacteria" show up as a sticky |
| developing a stringy, fibrous body. | | | | orange-red layer on some brine-washed |
| | | | cheeses. |
| Cheddaring: (Cheddar, other English cheeses) | | | | |