This article discusses pressing cheeses which is primarily performed on rennet coagulated lower moisture content aged cheeses after curds are prepared, (steps dependent on cheese type being made). Many cheeses have whey drained by gravity either by hanging the prepared curds in cheese cloth or by placing in a mold, these are not discussed in this article. Pressed cheese are in general pressed by placing the prepared curds in a cheese cloth lined hoop, on top of a draining mat, then placing a follower on top of the curds and then placing weights on top of the follower.
The goals of pressing the prepared curds are to:
- Reform a large cheese shaped drier curd, normally without any voids.
- To dehydrate the curd at the surface and form a tough rind that is less susceptible to unwanted micro-organisms.
- To knit the curds into a homogeneous cheese.
Some cheeses when manufactured in large wheels such as Stilton are not externally pressed, but are effectively pressed under their own weight. Making smaller artisan or hobby sized wheels of these cheeses often requires light pressing. Some cheeses such as washed curd Gouda’s need only light pressure versus some like cheddar require high pressure to form a knit. However, Dutch cheese makers of old pressed their large wheels with high pressures not to form a knit but to form a very dry and hard environmentally resistant rind as they had poor control of the weather and thus poor control of their aging environment.
Hoops & Molds
In gravity draining whey from cheese, commonly a thin mold or hoop and mats are used. In pressed cheeses the form is often called a hoop as it was historically in the shape of a round hoop as that shape was better to withstand the sometimes high hoop stresses from the applied weights.
Inside a cloth liner was placed inside the hoop in hold the initially moist and soft curds, but modern manufacturing has enabled more heavy-duty mold type devices with integrated bottoms and form fitted mesh liners and lids.
The following is the standard method for pressing cheeses, it will vary depending on hoop or mold type and on cheese type.
- A hoop, commonly with small holes to enable whey expulsion is placed on some sort of mat that additionally allows whey to flow out of the bottom of the cheese.
- Inside the hoop a cloth is placed to initially hold the curds so that they aren’t extruded out the holes.
- The prepared curds are placed in the cloth and a round disk-shaped “follower” placed on top of the curds.
- While pushing down on the follower, the cloth is pulled up straight all the way around the sides to minimize wrinkle-fold lines in the sides of the cheese.
- Initially a light weight is applied on top of follower to apply a light pressure. Going light at first gives the excess whey in the interior time to move out of the cheese before the curds at the edge are dehydrated effectively sealing the whey inside the cheese, a location for unwanted micro-organisms to grow. If heavy weight/high pressure was applied initially then i) the fresh very soft curd can be extruded up around the follower or out of weep holes if no liner is used, and ii) the curds at the surface would rapidly dehydrate forming a barrier to further whey expulsion.
- After a short period, the very sort formed single curd is removed from the cloth and turned and replaced. Again while pushing down on the follower pull the cloth up verticlly aroound the circumference of the formed curd and then apply a heavier pressure. This is to i) enable the previously top of cheese to also form a slightly dehydrated layer and ii) enable a more uniform shaped and moisture content cheese to be created, iii) to minimize the curds impregnating and sticking to the cloth, and iv) to minimize cloth wrinkle-fold lines on side of the forming cheese.
- The above step is repeated with steadily longer times between turnings and with steadily higher pressures, depending on the cheese type and recipe-procedure.
- Some cheese makers only use the cloth lining for the initial light pressings to minimize the cloth imprint around the sides of the cylinder during higher pressure pressings.
- Some cloths are sewn to snuggly fit the inside of the hoop and thereby reduce ridge lines around the periphery of the cheese.
Presses range from the simple improvised (exercise hand weight, jugs of water, step-ladder balanced one end on the hoop) to highly leveraged or geared machines to modern pneumatic (air powered) machines and are the subject of a future separate article.
Tricks & Traps
Common tricks and traps in pressing cheeses are:
- Sticking of the curds to the cheesecloth of hoops or to the mesh liner in some molds, this normally occurs when the curds pH is too low or when the weave is too coarse and the pressed curds are imbedded into the cloth. Solutions are to turn the cheese a few times in the first couple of hours to build up a good rind, use a tighter weave, and additionally if required to soak the cloth or nets with warm whey with addition of Calcium Chloride (warmth helps curds to knit) or to spray with a salt/vinegar/CaCl2 solution. If required the cloth liner can be additionally sprayed between cheese turnings while in the press.