Saturday, January 21, 2012

Annoying Issue #1 Temperature Control

    If you suffer from Obsessive Compulsive Disorder, the first thing that will strike you when reading a cheese making recipe is the necessity of temperature control.  The cheese books, so encouraging in their efforts to get you making cheese, deal with these issues in the most annoyingly off-handed way.  It's like asking an Apollo astronaut how he made it to the moon and his reply is: "Yeah....sooo....go really fast towards the moon...and don't slow down or you'll die...and also don't go too fast or you'll also die". The fact is cheese requires slow temperature change. It requires this at nearly every stage. So what's the problem? Uh

Specific Heat and You: A Guide For Cheese Makers Bored By Thermodynamics

     Water is kind of amazing, it's always been so.  Water seems to dissolve everything Man needs dissolved, keeps us hydrated, and is willing to look lovely on Caribbean vacations.  Water, in it's more prosaic moments, also plays a monumental role in home cheese making.
     Look over the cheese recipe in front of you. What does it say?

Something like:

"Raise temperature from 90 degrees F to 102 degrees F at a rate not exceeding 2 degrees per 5 minutes"

     If you're anything like me your response was understandably:  F#@K YOU....WHAT?

     It's a tough problem, and physics is involved. It goes a bit like this. Every liquid has a property known as Specific Heat and that's important here.  Reading the actual description of this property can be a bit obtuse and frankly un-sexy. Let me attempt to express it in a sexier way without violating all known physical science.

     Remember Inertia? The property that says that bodies in motion tend to stay in motion while bodies at rest tend to stay a rest?  Well, there's a bit more to remember about that assertion, namely, HUGE bodies at rest tend to stay at rest a lot and HUGE bodies in motion tend to stay in, a lot.
     Without digging too far into physics, we can think of the Specific Heat of liquids as a kind of Inertia, only in this case its temperature, not motion (yes physicists, I know its effectively the same)

So know this about water..and milk, which is mostly water......H2O is like the Barry Bonds of Specific Heat...
Picture this: Near Pure Ethyl Alcohol (Moonshine) is a skateboard, Water (water) is a Mack truck.

     Ok. I push the Moonshine skateboard, it quickly attains speed and screams along the pavement. My buddy, 50 feet away, stops the Moonshine skateboard with little more than the touch of his hand. Easy to start, easy to stop. Translation: Low Specific Heat.  My buddy now fires up Water Mack Truck....after some diesel gasping it trudges down the road.....slowly yes, but now nearly impossible to least with anything less than another Mack Truck. Translation: High Specific Heat.

     Most home cheese making recipes will recommend that when you heat your milk, namely the two or three times in the process that you have to change it to specific temperatures, that you do so in a water bath...the most common reccomendation is that you bathe your milk pot in a sink full of hot water and slowly bring the milk to temperature. This is wise...the buffer of starting and rolling-out the "diesel truck" allows the heating to occur slowly.  So what's the problem?

     The problem is, as I see it, or rather saw it on my first attempt, is that feathering the throttle of a Mack Truck is no mean feat. Just when you see the temperature of the milk stagnate, you add hot water to the bath to heat it.  You now find that your cold situation is now a hot situation with the milk temperature rising out of add cold water to fix it....and the inverse happens.  Turns out that the ideal situation is when the bath water is about 10 degrees hotter than the target temperature for the milk. This insures attainment of the target temperature for the milk without overshooting or gaining temperature too fast. But how do you maintain the speed of two dependent Mack trucks at the same time?
        Though no book has suggested it, ridiculously enough, I think you see the simple solution to the problem: USE TWO THERMOMETERS. One goes into the surrounding water bath and one (sterilized) goes into the cooking milk.  Because the stakes are lower in the water bath, namely it's not as temperature-sensitive as the milk, you can fuss with it a bit, and head-off temperature spikes before they happen. The second thermometer gives you data about the VERY sensitive milk and makes sure it stays within it's narrow window at each moment during the process.

     I neglected to have this epiphany BEFORE making my first batch of cheese and well, I got lucky...It turned into cheese....tomorrow I will buy an additional thermometer and go another round, this time with more data.

Tune in here to see my results.

     Also, make no mistake this is not by far the last we have heard of temperature, quite the opposite. One could scarcely imagine all the hair-brained schemes and dangerous scenarios I have cooked up for temperature control, or for that matter, any other step in the process.

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