Bob Albers is a retired electrical engineer who lives in Mandeville, Louisianna. In May, he sent us his recipe for Creole Cream Cheese (click here) and he will be our Spotlight in the upcoming August Moos-Letter.
If you’ve ever wondered why we recommend cooking your curds with the double boiler method, here’s a simple explanation and “the last word” from an authority on the subject:
The Thermodynamics of Cooking Curd
By Bob Albers
Pardon me for being so brash as to tell experienced cheese makers about how to cook their curd. I am new to cheese making but I’ve been an engineer for a long time. While thermodynamics isn’t a hot topic (pun intended) amongst us electronics engineers, we do dabble in it on occasion but it is usually how to keep the equipment cool.
Let’s look at our objective in cooking curd. We want to heat the curd to a specific temperature distributed evenly through the curd mass. This is relatively easy for small batches and temperatures below 100ºF. In fact, if you live in the southern areas of the country, you could just make the cheese out doors on an 88 to 92F day. Just bring your milk to an outdoor cheese making area a few hours before starting the process. It is important to observe the caveat that the pot containing our milk, and eventually the curd, be either stainless steel, glass or enamelware.
Many articles have been written as to how one can immerse a pot in the kitchen sink filled with warm/hot water and cook the curd that way. Actually, for lower temperatures, that’s not a bad idea at all as the heat source is not only from the bottom of the pot but also from the side. As long as the required temperature is 10 degrees F or more lower than the water temperature you should do ok.
My water heater is set for about 140F and I suspect yours is near that also. For temperatures near that, it is rather inconvenient to keep a sink full of water near 140F as the temperature tends to drop as heat is absorbed by the pot of curd and also escapes through the walls of the sink. One must constantly refresh the hot water in the sink. This difficulty leads many home cheese makers to place the curd pot on the stove.
A stove top is a tricky thing to use. Consider a gas stove. The temperature of the flame is in excess of 2500F. Because of this, the bottom of the pot can reach temperatures high enough to scald the milk/curd near the bottom without even showing any sign of high temperatures near the middle of the milk/curd mass. Indeed, heat “travels.” First is the heat traveling from the flame to the outermost areas of the pot. As that portion of the pot is heated, the heat travels to the inner surface of the pot. As this happens, the heat also disperses up and out into the full mass of the pot bottom. This is why pots with a very thick bottom cook better than those with thin bottoms. Hot zones are minimized by thick bottoms and the food in the bottom is heated more evenly. As milk is a liquid, the hot milk at the bottom of the pot rises to the top and the cooler milk at the top sinks to the bottom where it is heated. If the pot bottom is too hot, this circulation isn’t fast enough to prevent the milk at the bottom from scalding. That’s why the pot must be stirred constantly. Although an electric stove heating element rarely gets over 1500F, the same principles cited above apply, though at a slower pace.
It should also be noted that, as the bottom of the pot absorbs heat from the heat source, heat is constantly lost through the pot sides and top. As such, stove top heating can give uneven results. A better way to cook milk/curd is with a double boiler. The outer pot, which I will call the boiler takes all the heat from the source and distributes it to the inner (curd) pot. As the bottom of the curd pot is not in contact with the heat source nor is it in contact with the bottom of the boiler, heat is transferred to the curd by the water in the boiler. As mentioned above, the water in the boiler circulates from the bottom of the boiler to the top. There is very little difference in temperature of the water at the bottom outside of the curd pot and the top. Heat is transferred to the curd, not only from the bottom of the pot but also through the sides. The sides of the curd pot are a source of heat to the curd, no longer where heat gets lost. This results in a more evenly heated curd.
Another observation is that no food elements come in direct contact with the boiler pot, therefore the material making the boiler needn’t be ideal for cheese making. Only the curd pot has this requirement. This consideration is important as the cost of a 20 qt. stainless steel double boiler can be prohibitive leading one to consider selling one’s first born into slavery to raise the money. While some may consider this a good swap, I suspect most have a higher regard for our progeny. Perhaps a more economical approach would be to use a stainless steel curd pot with a larger boiler like a canning pot. Most canning pots come with a wire rack which would be used to elevate the curd pot from the bottom. The point of this is that the substance from which the boiler pot is made and it’s condition are irrelevant.
For those of us who live in the warmer areas of the country there is the patio consideration. According to my indoor/outdoor thermometer, the temperature on my patio now is 92. Had I placed some milk there last night, it would be ready for me to make cheese right now. All I would need is a single stainless steel pot-no boiler pot, no stove. How many cheeses can we make using the temperature range of 80to 100F? Just wait for the right day. Mother nature can do the work.
I hope this helps the more creative and imaginative to consider a wealth of ways to cook curd. I haven’t yet tried an induction type burner. I suspect one might not exhibit hot spots. Bon Appetit!