Abstract
There is more than one way to skin a … beetroot. So, there are many ways to cook and everyone relies on various physical principles and rules. The food we get from each method is also quite different. Sometimes, the same ingredients will even give us a different-tasting result because the temperature is different or there is less stirring or a different sequence or some other parameter. Many gourmet dishes started life as a serendipitous mistake!
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Notes
- 1.
This is due to the relative entropy of the gas–liquid phases.
- 2.
That’s the basis for driving steam turbines made to turn generators and produce electricity. By heating the boiling water in a closed vessel, the steam temperature and pressure increase hugely which is then able to turn the steam turbines.
- 3.
The white only starts hardening at about 65 °C and the yolk at about 70 °C.
- 4.
Although the relative amount of oxygen in the air is the same, about 21%, the total oxygen available to us is about four fifths of this.
- 5.
Copper has one of the highest thermal conductivities of all metals. It also has a very high electrical conductivity, so it’s used for wires.
- 6.
Generally, only the egg yolk is used, but I find using the whole egg gives a smoother texture, as the albumin aids in polymerisation, even if it is trickier.
- 7.
Alternatively, you can remove some of the hot broth and prepare the sauce separately. I don’t, as I like the sauce to diffuse into the food for a while before serving. It adds to the pleasure.
- 8.
Because it’s difficult to get the sauce right, many restaurants just offer béchamel instead, which I consider a bit of a cheat.
- 9.
According to the ideal gas law that we discussed before, for a closed system PV = cT, where P is the pressure, V the volume, T the temperature, and c a constant. In a pressure cooker, V is constant, so increasing P will increase T. It’s the same law that results in a bicycle tire getting hotter when we pump it up.
- 10.
However, you should always throw away the “first” water (after soaking or initial boiling for 10 min) to reduce various indigestible compounds and avoid excess generation of gases later on.
- 11.
Microwave heating was first discovered over 60 years ago, during the development of radar, which also uses microwaves, as we’ll discuss later.
- 12.
I guess it’s the word “irradiated” that may have given MWs a bad name. People somehow associate irradiation with X-rays or γ-rays and forget that we are all irradiated all the time by visible photons with much higher energies than MW.
- 13.
As we saw earlier, microwave photons have thousands of times less energy than infrared (heating) photons and millions of times less energy than visible light.
- 14.
Both are quite strong aperitifs from the eastern Mediterranean, with 40% or more alcohol. They are both made by double distillation of grapes with skin and stalks, but while ouzo has a strong aniseed aroma and flavor, raki is more fruity. Other similar drinks are pastis, raku, tsipouro, and arak.
- 15.
For the cooks out there, I also add chopped onion, garlic, and tomatoes too, plus salt and pepper with the ouzo, and boil at least 10 min before adding the pasta.
- 16.
Restaurants do something similar, but instead of pasta, they add starch (or water saved from boiled pasta) so they have a ready sauce to add to any type of pasta or rice or other carbohydrate.
- 17.
That’s not all. Since sugar is no match for the high energy content of fats and other lipids, it cannot sustain us till our next main meal.
- 18.
It has the opposite optical polarization rotation to the original sucrose.
- 19.
Never margarine—it spoils the taste and I definitely do not believe it is as healthy an alternative as so much marketing would have us believe.
- 20.
Cross-linking is a random, complicated form of chemical bonding between different macromolecules, creating a rigid structure. Most hard polymers and epoxies are cross-linked, as are body cartilage and similar structures.
- 21.
An egg denatures every time we heat it. A very simple method I use for cooking an egg is in the microwave. I use a round shallow dish (a glass “petri” dish from the lab is perfect). Without oil, it will cook in under 1 min (at half power) to a perfect consistency. Go on, try it. You’ll never go back to frying.
- 22.
Even the clearest of consommés will contain many particles at the nanometer size (a billionth of a metre), and these can easily stick to the filter paper.
- 23.
They are the “water striders” we saw earlier. A few species have evolved to do that, including long-legged flies and a few types of spiders. And, of course, some fish have also evolved to nab them from below.
- 24.
In fact, most of the solutes (the nutrients) in such small pieces dissolve faster than if you use larger pieces, because their specific surface area is very large, allowing faster diffusion.
- 25.
Fish consommé also works well with young cod, scorpion, and similar lean fish. Sea bream, grouper, and sea bass make excellent rich, velvety soups.
- 26.
They affect the electrostatic repulsive forces of the water molecules.
- 27.
As soon as all water evaporates, food converts to and emits various gases which ignite, before final pyrolysis, which ends with carbon.
- 28.
Wood fires emit many toxic gases, especially hydrogen cyanide (HCN).
- 29.
Initially, coal will oxidise only partially, producing carbon monoxide (CO) another toxic gas. Later, it will produce carbon dioxide, assuming there is an ample supply of fresh air.
- 30.
A vibrating barbeque would do the job very well, by occasionally shaking the ash off the coals. I wonder if anyone has thought of it.
- 31.
I often wonder if the current situation in which the climate has been destabilised would have been milder or occurred more slowly if gas hobs (and air-conditioners too) had never become so ubiquitous. In many countries, they are used in up to 90% of homes.
- 32.
To be found everywhere at Easter in millions of Balkan homes and farms.
- 33.
Believed to have originated in Greece to produce the gyro. Also used for doner kebabs in Turkey and shawarma in the Middle East.
- 34.
As mentioned before, thermal expansion of materials is due to the greater vibration of atoms when heated. Ceramics and glasses expand a little, metals more, polymers and food even more, and liquids much more.
- 35.
Lots of high-temperature transformations in the kitchen give slightly toxic but tasteful by-products. It’s a case of balancing taste with safety while our liver expertly eliminates them over time.
- 36.
Both contain carbonates which quickly decompose above about 160 °C to give off carbon dioxide.
- 37.
Coarse pasta mixed with a mince and tomato sauce (“Bolognaise”), topped with béchamel and cheese is an extremely popular dish in Greece called “pastichio”. I personally prepare it layered with lasagna.
- 38.
Isn’t this what every living being is? All living bodies are huge symbiotic collections of trillions of individual cells, after all.
- 39.
This is done with vacuum-sealing apparatus that uses plastic bags of high density polyethylene (HDPE) or polypropylene (PP), never polyvinyl chloride (PVC) or low density polyethylene (PE). We’ll discuss the various types of plastics and their properties later.
- 40.
The name—but apparently not the dish—comes from the Arabic “mousaqqa” which means something like “pounded” or “cold”.
- 41.
“Half power” in MW ovens does not mean exactly that. It just means full power applied intermittently (i.e., “half the total energy”), as we’ll discuss later too.
- 42.
All materials evaporate, even at much lower than boiling temperatures, because of the random energy distribution of the molecules.
- 43.
It’s the membrane that sperm need to penetrate and fertilise the egg. As soon as one manages it —not a mean feat—the membrane reforms by cross-linking to form a hard, impervious structure.
- 44.
Heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAH) among others. All of them are dangerous, with strong indications of carcinogenicity.
- 45.
Releasing the “nutty” smelling chemical diacetyl.
- 46.
Free water is water that is not bound up with other chemicals or mechanically bound within cells and other structures in the food.
- 47.
What a misnomer. It should rather be called “badly done” or overdone or destroyed food.
- 48.
Greek vegan stuffed vine leaves (dolmadakia) or filled cabbage leaves (lahanodolmades) are good examples.
- 49.
But not impossible. Immune deficiency may allow fungal infections, but most are relatively easy to treat.
- 50.
Interesting examples are “biltong” from Southern Africa, “kilishi” from Nigeria, and “beef jerky” from the USA.
- 51.
There are some extremophile bacteria that can survive boiling, but they are extremely rare and certainly unheard of in a clean kitchen.
- 52.
All bacteria (microbes, viruses, spores, parasites) are enclosed in membranes made of various lipids which dissociate easily above 65 °C or in alcohol or under exposure to sunlight, resulting in their death.
- 53.
It is mainly moulds we should be concerned with in the kitchen, since bacterial contamination of cooked food is very rare unless it pre-existed in the ingredients and cooking was incomplete.
- 54.
Some condensation will occur in a humid atmosphere anyway, even if you cool down the food to room temperature. Transparent covers help to monitor any condensation so that you can remove it in time.
- 55.
Apparently, some people believe that drinking distilled water is healthy. It is nothing of the sort and actually quite dangerous in sufficient quantities as it destabilises the sodium/potassium balance across cell membranes.
- 56.
They used to be made of softened poly vinyl chloride (PVC, also used extensively for plastic containers until recently) until it was discovered that the phthalates used to soften PVC are very dangerous.
- 57.
Water would readily diffuse out of the food onto the surface until it reaches vapour balance.
- 58.
It used to be bisphenol-A-based plastic (BPA, an epoxy), but now other plastics are used, as BPA has also been found to be very dangerous.
- 59.
A half-filled plastic water bottle in the fridge will crumple and collapse for the same reason. This method is of course used by many industries to vacuum-pack jams and similar foods. When you twist the jar open (difficult, as you are working against atmospheric pressure—use a blunt knife under the rim), you hear a click telling you that you have “broken the vacuum” and let some air in.
- 60.
The general advice is that very young children, along with older, vulnerable people and everyone with weak immune systems, should be extra careful with any moulds.
- 61.
Even with a rotating table, some microwave ovens form hot spots on the food. The ones with convex or concave reflectors are better as they distribute heat more evenly.
- 62.
Polypropylene (PP) can be used up to about 100–120 °C, but microwave hot spots can reach higher temperatures. Glass presents no problem at all, even at much higher temperatures.
- 63.
Lipids dissociate much more quickly than proteins, even under bacteria-free conditions, as their molecular hydrogen bonds are weaker.
- 64.
You can ignore this for butcher-supplied game.
- 65.
Eatable means nice to eat, whereas edible means safe to eat.
- 66.
In most cases, “expiry dates” are recommendations, not restrictions, but you wouldn’t know it by listening to so much nonsense “advice” online and offline.
- 67.
For a brief introduction to various materials, see later.
- 68.
Oxidation of foods by ozone (O3) is much quicker than with ordinary oxygen (O2) so it’s an excellent antibacterial and antifungal agent. It is also a pollutant generated by older types of electric motors and everywhere where there is electric arcing and very intense sun light.
- 69.
The high energy of UV photons can easily break up some of the vitamins’ weak bonds. It can also affect proteins and even carbohydrates.
- 70.
For any iceberg, only about 1/11 of its mass is visible above the surface. The rest is underwater.
- 71.
Moulds and slimes are known to grow happily even in Antarctica.
- 72.
Both are generally used to defrost ice on roads and other surfaces.
- 73.
One can say that green is a useless wavelength for the growth of plants. The same happens in some highways illuminated by monochromatic “yellow sodium arc lamps”—all cars other than yellow appear black.
- 74.
Use green tea leaves or add a few drops of lemon to lighten up the tea (by bonding with some of the tea molecules) in order to see their motion more clearly.
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Vekinis, G. (2023). Gourmet Physics. In: Physics in the Kitchen. Copernicus Books . Springer, Cham. https://doi.org/10.1007/978-3-031-34407-7_4
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