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