Monday, August 3, 2020

Food: The Big Opportunity In Oxidation

Actually, preventing oxidation.
For oxidation you want Chlorine Trifluoride.*

From ScienceNorway:

What do crabs and fruit have in common?
Did you know that crabs do not need to be cooked in boiling water in order to become delicious food? And what on Earth do crabs, fruits and vegetables have in common?
I have been working as a student and a researcher examining the quality of commercial crab species for some years now. People usually become quite curious when they hear that I am researching crabs. They ask me all kinds of interesting and difficult questions about the physiology and biology of crabs. However, there is one thing that everyone seems to know: Crabs must be cooked in boiling water with some added salt!

Not surprisingly, the crab industry also employs the same method of preparation, that is to immerse the crabs at the boiling point, except at a larger scale using large tanks. This process has not changed for decades. Can the heat-treatment of crabs be done differently in an attempt to increase quality? If so, what sort of challenges might arise from such a change?

Why do crabs need to be heat-treated?
The aim of the heat-treatment is primarily to coagulate muscle proteins so that the meat becomes edible and detaches from the exoskeleton (shell).
In addition, the process reduces the microbial load and prevents bacterial growth. It also gives the crab shell its characteristic reddish-orange colour.

Do we need boiling water?
Crab meat is ready to eat when it reaches a temperature between 72–78 °C.
International guidelines on ready-to-eat seafood recommend that crab meat should be heat treated at 70 °C for at least two minutes in order to reduce the microbial load. The meat is then safe to eat for up to ten days when stored at 0–4 °C.
The characteristic colour of heat-treated shellfish comes from a pigment called astaxanthin. This compound is bound to a protein in the raw crab but is released when the temperature is high enough, causing the shell to turn from a brown to reddish-orange colour. This reaction does not require a cooking temperature higher than 75 °C, either.
Therefore, it is not necessary to use boiling water when cooking crabs.

Lower temperature, more value
There can be many advantages of heat-treating crabs at a temperature lower than the boiling point, in a so-called mild cooking process. First and foremost, it saves energy and it reduces the time necessary to heat up the water between cooking batches. In addition, it may help make the process more controllable avoiding overcooking the meat located in proximity to the shell. Furthermore, the crab shell acquires a more vivid red colour and the meat is whiter.

Lower heat-treatment temperatures have already been employed in some European countries when processing brown crab (the most common crab species in Europe) into ready-to-eat products. In the UK, Ireland and France, these are sold as a premium quality and highly-priced products.

Red or blue crab?
For some species of crab, however, the application of a mild cooking process can pose some challenges. Snow crabs, for example, can get bluish-black spots on their shells. These spots are caused by melanin pigments which form as a result of the enzyme process called melanosis – also known as blackening or bluing.
Snow crabs easily get blue or black spots.

Snow crabs easily get blue or black spots. Photo: Wilhelm Solheim/Nofima
This discolouration does not mean that the crab is dangerous to eat, but it does ruin its appearance. The industry calls this discolouration problem ‘bluing’.

Stressed or wounded crabs is never a good thing
Why does this discolouration happen? This is where we must delve into the world of biochemistry. The key factor that causes this bluing reaction is an enzyme called polyphenol oxidase, and it plays a very important role in the crab’s immune system. When a crab becomes stressed, is wounded or has an infection (in other words, when it is under attack!), its immune response is triggered. It emits biochemical signals that activate the enzyme responsible for bluing. Among other things, crabs use these dark compounds (melanins) to seal open-cut wounds.

The enzymatic process can occur very quickly, especially after the death of the animal during processing. However, the bluing reaction can be stopped by inactivating the enzyme through heat-treatment, but the temperature needs to be between 85 and 90 °C and should be applied for at least half an hour....

So halt the action of the polyphenol oxidase et voilĂ , no spots.
On the other hand:

Pure Evil: The Chemical So Awful It Can Burn Rust or Sand
A repost from 2017:

How the hell do you burn something that is already oxidized?

Meet Chlorine Trifluoride: The Chemical That Sets Fire to Asbestos on Contact
From Gizmodo, July 2015:

First discovered back in the 1930s, chlorine trifluoride is a rather curious chemical that easily reacts, sometimes explosively, with just about every known substance on Earth.

Just to get the ball rolling, here’s a few of the more unusual things chlorine trifluoride is known to set fire to on contact: glass, sand, asbestos, rust, concrete, people, pyrex, cloth, and the dreams of children…

Obviously the first question to answer here is how chlorine trifluoride is somehow able to cause asbestos, a substance that is known for being almost completely fire retardant, to catch on fire. Well, that’s because chlorine trifluoride is a more powerful oxidizing agent by mass than oxygen itself. Meaning it’s capable of rapidly oxidizing things that would normally be considered practically “impossible” to set aflame, like asbestos. Chlorine trifluoride is such an effective oxidizer that it can even potentially set fire to things that have seemingly already been burned up, like ash or spent charcoal.

The substance is so highly reactive that famously unreactive elements like platinum, osmium and iridium will begin to corrode when they come into contact with it. Notably tough elements like titanium and tungsten are also regarded as being wholly unsuitable to storing the chemical because they set on fire as soon as they come into contact with it.

The only known way to store chlorine trifluoride “safely”, which we use in the loosest possible sense, is to put it inside of a sealed containers made of steel, iron, nickel or copper which are able to contain the chemical safely if they’re first treated with flourine gas. This is because doing so will coat the metal in a thin fluoride layer, with which the chemical won’t react. However, if this layer is compromised in anyway, or the metal isn’t completely dry, chlorine trifluoride will begin to react violently and cause the vessel to explode.

A few of the other things known to not react with chlorine trifluoride include nitrogen, the inert gases and polychlorotrifluoroethylene. Rather fortunately, chlorine trifluoride doesn’t react with air unless it happens to contain a larger than average amount of water vapor.

Speaking of which, when chlorine trifluoride comes into contact with water, it will react explosively with it and as a fun byproduct creates large amounts of dangerous gasses such as hydrofluoric acid and hydrochloric acid. Hydrofluric acid in particular is incredibly dangerous and along with being able to melt things like glass and concrete, can permanently damage your lungs and eyes. As if that wasn’t worrying enough, if you’re ever unlucky enough to get hydrofluric acid on your skin, it doesn’t actually hurt until a few hours later. After it has absorbed a bit, it starts destroying your nerves and bones and can ultimately cause cardiac arrest when it gets into your blood stream. In fact, in 1994 a lab technician in Australia accidentally spilled hydrofluric acid on his lap and despite immediately executing safety procedures including hosing off, immersing himself in a swimming pool, and later extensive medical care (including needing to have one of his legs amputated), within two weeks of the accident, he was dead.

Unsurprisingly, the Nazis were really interested in the military applications of chlorine trifluoride. After all, it’s a substance that reacts explosively with water (humans are largely bags of water), and for those that don’t come in contact with it directly, there’s the byproduct of the deadly gasses. Further, there is really little one can do to put out the fires it causes directly other than to let them burn off. If you throw water on the source of the problem, it will get worse. The reaction here also doesn’t require atmospheric oxygen to burn, so trying to use that method of fire suppression won’t work either....MORE