Bacterial-Ripened Cheeses (Washed-Rind/Smear-Ripened Cheeses)

Like many things cheese-related, the practice of washing cheese rinds started in France, where sixteenth century monks used to make cheeses in their monasteries as a way to feed themselves. The conditions in monastery cellars were ideal for cheese bacteria, but because the conditions weren’t easily controlled, the cheeses were more liable to develop bad rinds. To avoid this, the monks used to wash the rinds with whatever they had to hand.

The monks relied on cheese as a source of protein, and the profits they made from selling cheese became critical for running their monasteries. Many monks in the Medieval age were brewers and distillers as well, so some began lacing their cheese brines with booze for added flavor, complexity and preservation power. This style of rind washing created softer, creamier cheeses – Epoisse de Bourgogne is one of the earliest and best examples of a soft, washed-rind cheese. The creamier examples of washed-rind cheeses are now called "monastic" cheeses, with recipe origins in the Franciscan monastaries of France and Belgium.

A similar practice emerged in mountain areas around the same time – the extreme humidity of the mountains made it tricky to control the growth of cheese bacteria. As a result, cheesemakers began washing their rinds, but because drinkable water was plentiful in the mountains, they used brine rather than alcohol. Brine creates rather different conditions on the surface of the cheese, and results in harder cheeses. Gruyère is a perfect example of this – the cheese originated in the town of Gruyères, perched at around 2,500 feet above sea level in the Swiss alps.

Technically, "washed rind" is a phrase that can be used to describe any cheese with a brine-washed (or moistened) rind. During ripening, the cheeses are washed with a dilute solution of saline to spread the organisms growing on the outside more uniformly. For this reason, these cheeses are also called washed-rind cheeses. Adding mildly salted water to a cheese's exterior fosters an environment hospitable to a variety of bacteria, often (though not always) including Brevibacterium linens. Many cheesemakers include b. linens directly in their brine, while others introduce it to the milk prior to cheesemaking when making these cheeses.

In Kitchen Cheesemaking, Lue Dean Frank, Jr. says that you can either buy the required culture from a supply store (easiest), or you can innoculate the cheese with a surface-ripened cheese bought at the grocery store (fastest). Buy a small package of Limburger or Brick. Then rub the surface of your newly made cheese with the Limburger or Brick. The bacteria will be now on the surface and all you need to do is "smear" the surface, which means to massage the outside of the cheeses with a little warm, salt water so that the bacteria will be spread about in the process.

Muenster traditionally has an orange rind. This is added by cheese factories by drying off the surface after the initial curing of four days, then mixing oil with annatto coloring and rubbing it on the rind. Let cure for four weeks for a mild flavor.

The bacteria that develop when making cheese this way are responsible for the unique characteristics of the cheeses' rinds, the reddish color, and pungent smell. Washed rind cheese with a high moisture content gets broken down by these bacteria, resulting in a creamy cheese that becomes oozier with age. By comparison, low moisture washed rind cheese (like Gruyère and others traditionally made in the Swiss and French Alps) become firmer and drier as they age. Many of these cheeses are only aged for a few months.

These bacterial surface-ripened cheeses can be hard, e.g. Gruyère, Beaufort, Appenzeller and Comté, semi-hard, e.g. Tilsit, Brick, Fontina, Taleggio, Raclette, and Limburger, or soft, e.g. Münster, Livarot and Reblochon. Typically, hard, surface-ripened cheeses are made with thermophilic starter cultures and the semi-hard and soft cheeses with mesophilic ones. Only limited cooking (35 °C) is given to the curd of the cheeses made with mesophilic cultures and, consequently, these cheeses have relatively high moisture contents.

During one of the most important steps, aging, a number of enzymatic reactions occur that result in complex flavors. Microbial organisms (bacteria, yeasts, molds) breakdown proteins, fats and sugars in the cheese, which create aromatic compounds. These flavors gain intensity and complexity as the cheese ages, and the body and texture of the cheese changes. The caseins in the cheese undergo proteolysis (breakdown) and the cheese body softens from the enzymes in the paste of the cheese. As surface-ripened cheeses age, flavor compounds produced by the surface microbiota move from the outside of the cheese to the inside. Brevibacteria and other bacteria in associative growth with yeast results in an orange/red/brown color that we see on cheeses like Limburger or aged Brick depending on the colonies present on the cheese.

The cheeses are ripened under conditions that promote microbial growth, e.g. relative humidities of >90% and temperatures of 10–20 °C. Therefore, the only microorganisms that grow on the surface are those that can grow at high salt concentrations, low pH and at these temperatures.

Today, the cheesemaker smears the cheese by spraying or sponging a Brevibacterium linen bath over the cheese as it ages. The washing keeps the cheese moist, prevents contamination by undesirable bacteria, lends a healthy antibody to the rind. The smear is rubbed, brushed or sprayed on the cheese surface at least once a day early in the initial aging process. Repeated turning of cheeses and surface treatment by repeated smearing (brushing) are most important for ripening.

The smear liquid is made up in water or whey containing B3% salt to mirror the salinity of the cheeses and is generally inoculated by commercially available surface starters.