Make Cheese while the Snow Falls
Friday, January 28, 2011 at 01:05PM 
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"Farmer cheese" forming curds with the addition of vinegar at high heat. At right, the finished product.
While the ground is frozen and we are still waiting to start maple sugaring, Daisy continues to turn hay and grain into milk for us. We have been making butter, ice cream and cheese from the milk.
It is useful to organize cheeses into families based on the distinct ways used to coagulate the fat and protein of milk. All cheese-making is concerned with removing lactose and water to concentrate milk’s proteins and fats but there are a multiplicity of methods to achieve this end.
The most simple cheeses, among them Cottage Cheese and Cream Cheese, use acid as a coagulant. The acid is typically from a lactic-acid producing bacterial culture. These cheeses require only minimal cooking after curds form to prevent an active culture from producing further acid. These cheeses have high moisture content and should be eaten within 2 to 3 weeks.
Fresh cheeses like Queso Blanco and Queso Fresco use the enzyme rennet as the coagulant. Rennet can be derived from the stomach of a calf or other ruminant, or extracted from a certain plants, including the common pasture plant bedstraw (Galium spp.). Rennet-coagulated cheeses use no acid-producing culture, and so the pH remains close to neutral. This is a benefit for a cook who wants a cheese that can be fried, but it can be risky to store a cheese at such a high pH because more microorganisms may thrive. Some cheese-makers add a culture to Queso Blanco to reduce the pH to about 5.8, slowing the growth of microorganisms but maintaining enough alkalinity to make a cheese that won't melt in the skillet.
Our “farmer cheese” is a heat-acid precipiatated cheese in the style of Ricotta and the Indian cheeses Channa and Paneer. No fermentation or culturing is involved. We have been making this cheese regularly and the procedure is simply to heat the whole milk to about 175 F and then add acid. The cheese curds form within seconds, separating from the increasingly yellow whey. We use apple cider vinegar because it was commonly available in the early 1900s to New Jersey farmers, but any organic acid will do the trick. Lactic and citric acids are most commonly employed.
One fascinating advantage that heat-acid cheeses have over other simple cheeses is that the high heat denatures the whey protein, making it available to be coagulated along with the protein casein when acid is added. This greatly increases the yield and protein punch of the final product. Furthermore, the whey protein bonds well to water and so the resulting cheese holds great moisture content but is quite firm.
The second marvel of heat-acid cheeses is that they have a pH in the skillet-worthy range, between 5.2 and 6.0, because milk at high heat requires less acid to coagulate protein.
For the curious, an extremely comprehensive guide to cheese making and all things dairy can be found at the University of Guelph's website on Dairy Science. Use your google or cut and paste this link: http://www.foodscience.uoguelph.ca/dairyedu/home.html
Stay tuned for dairy demonstrations at the farm in the near future.
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