This article discusses how to break or cut the coagulated milk, a critical process in making cheese. When to break or cut the curd is discussed in the article Wiki: Curds, When to Cut.
When the milk first coagulates, it has a natural tendency to contract and expel whey. This property is called syneresis and it depends on several factors, the largest being surface area of the coagulum or curd. Small surface area versus volume of the coagulum results in slower and less whey expulsion, larger surface area results in faster/more whey expulsion. The purpose of cutting or breaking the curd is to increase it’s surface area and thereby increase it’s expulsion of whey and reduce the water content of the curds and in the final cheese.
Lactic Acid Coagulated Cheeses
Lactic acid coagulated cheeses commonly employ three different methods to break or cut the coagulum depending on cheese type:
- Some cheeses such as Quark are broken by simply stirring the coagulum.
- Some cheese such as Cream Cheese are ladled directly from the coagulum in the vat into the cheese cloth or molds without being cut or stirred.
- Some cheeses such as Cottage Cheese are cut with wire knives similar to rennet coagulated cheeses.
Rennet Coagulated Cheeses
Rennet coagulum’s are normally cut into similar size particles, the size and shape varies depending on the type of cheese being made. Smaller cut curds generally result in drier cheese, larger in moister cheese. The cutting patterns listed below have been refined over centuries of cheese making to allow the right amount of whey to be expelled for that type of cheese. Ideally every curd particle is of the same size to:
- Create a uniform cheese, large range in cut curd sizes will result in areas of high and low moisture content in the cheese. High moisture can result in sour or fermented areas.
- Create uniform temperature among the cut curds, especially if cooking the curds. Different sized cut curds will heat at different rates resulting in different internal temperatures which will cause differing whey expulsion and acid production rates.
Method: Cubed Cutting
Cutting of the coagulum into cubes is the most common system and used for making many cheeses. Cut sizes range from 6-25 mm / 0.25-1 inch cubes, for example Cheddar normally requires 1 cm / 3/8″ cubes. To cut the cubes, commercial cheese makers normally use rectangular shaped Curd Cutters or Harps or Curd Knife with evenly spaced wires. Two of these tools are normally used, the first with horizontal wires to cut the coagulum into horizontal sheets, the second with vertical wires to cut vertically into horizontal square rods and then again vertically but at 90 degrees to create the cubes. Generally a cross-hatched grid curd cutter is only used for large sized cut curds, as for smaller it generally tears the curd into irregular sized pieces as the forces on the curd are too great.
These professional Curd Cutters are normally built to match the size and shape of the large volume vat. Home/hobby small scale cheese makers commonly use a large stockpot for their vat. For them, a common workaround is to use a long thin food grade object as a Curd Knife and:
- First, slice the curd vertically into parallel even thickness sheets.
- Second, slice the curd again vertically but perpendicular, at 90 degrees to the first row, resulting in vertical square rods of curd.
- Third, slice a third row of cuts but at 45 degrees to the first two rows of vertical cuts and with the curd knife tilted at 45 degrees from vertical to form “diamond” shaped cut curds.
- Fourth, a row of cuts at 90 degrees to the previous 45 degree row and with knife still tilted at 45 degrees, to fully and reasonably evenly form the cut curds.
- Fifth, circle the knife around the edge of vat to detach cut curd from vat.
Common kitchen examples for a stockpot Curd Knife are: Bread Knife, Cake Knife, or Icing Spatula. Note, if the tool is too thick (like a metal cookie cooling rack) then the curd will be torn rather than cut.
Method: Rice Cutting
Drier type cheeses like Swiss normally have the coagulum cut into rice sized pieces using a “Spino” harp shaped tool. Often this is improvised in home/hobby cheese making by using a large metal whisk.
Method: Italian Cutting
An egg shaped device for Italian cheeses. Again, this is often improvised in home/hobby cheese making by using a large metal whisk.
Method: Partial Cutting
Camembert cheese making uses only parallel vertical cuts and sometimes 90 degree parallel vertical cuts resulting in long square rods of cut curd. This is normally done with a long single cutting knife or sword. The partially cut curd is then horizontally cut by a tool called a Pelle or with a flat ladle when removing the cut curds from the vat and placing them into the gravity draining hoops.