Friday, 14 October 2016

Thermodynamics of cooking sources

There is obviously a link between food and thermodynamics, and it's not hard to see eating as primarily a means of getting energy into the body. 

In What is Life (the 1944 book by Erwin Schrödinger, not the 1970 George Harrison song), the physicist and theoretical cat-tormentor turned his hand to deep biology. His view seems to have been that the meaning of life is basically beating the second law of thermodynamics by moving energy from the colder bits of the universe into hotter bodies, and beating entropy by promoting some kind of order out of the inevitably increasing chaos.

Schrödinger inspired Watson and Crick in their search for the double helix, and in turn he was standing on the shoulders of Darwin, who had brought the field of biology well into the realm of science from its previous home somewhere down the corridor from stamp collecting.

In terms of evolution, getting energy into the body has been an important part of our development, and the taming of fire was a big breakthrough. Once we applied that to food, we got a double benefit of increasing the number of things we were able to eat, and reducing their volume and the time it took us to eat them. 

Previously I suggested that Watt invented the positive feedback loop that led coal to be used to power pumps that would remove water out of mines and allow more coal to be removed. But perhaps this wasn't really an invention, but simply another application of something humans have been doing for a very long time. 

It's Interesting that calories are now more often seen as enemies, to be scanned on packages, counted, and where possible reduced. Personally I always look at the label when I'm choosing what food to buy, and usually get the food with the largest number of calories since that's what I'm paying for. While some people are desperately trying to reduce the calories in the food, we rarely look at how many calories of energy went into preparation, packaging and transport of the food.

Early attempts at cooking were not so efficient. Wood was most likely the fuel, and little of the heat will have gone into the cooking, so most of the energy was going up in smoke rather than into those hungry human stomachs. 

This discussion on Ask Historians looks at the effects of gas and electric stoves on lifestyle, with many suggesting a revolution in the twentieth century, when cooking stopped being a full time job, and kitchens were no longer dedicated to food preparation, but became integrated into dining rooms. 

Another big innovation has been the microwave oven. Although scorned by a lot of people concerned about health and nutrition, and pining for "real" cooking, microwaves may be more efficient. Of course microwaves do put out radiation, but so do all other cooking appliances. Instead of sending out a broad spectrum of radiation, microwaves focus on frequencies that will excite the water molecules, and however you wrap it up in culinary language, cooking is basically about removing water. Also, you don't need to heat up a heavy metal container to cook what is inside a microwave, so it should be more efficient, but any efficiency is likely to be marginal, and savings will be much less than the energy used to read this.

(Picture stolen from: Green Lifestyle Magazine