The scientist's view of the kitchen world
A wise woman puts a grain of sugar into everything she says to a man, and takes a grain of salt with everything he says to her.
Let’s take a look at the most useful kitchen item – the one you use in almost every dish – while dispelling some myths, shall we?
Before I begin, I need to put in a disclaimer: I am a physicist (fluid dynamicist to be exact), not a chemist so please forgive the rather cursory overview of the chemical structure. If I get anything wrong, please let me know!
As the title to this post suggests, salt, the kind you put on your table, consists of one sodium atom and one chlorine atom. Together, these make sodium chloride. However, this story isn’t quite so simple. One can’t simply throw a sodium atom at a chlorine atom and come away with salt, we need to mess around with electrons a bit. Sodium chloride is an ionic compound which means that a positive sodium ion (one that has lost an electron) forms an ionic bond with a negative chlorine ion (one that has one electron too many).
So before I risk getting into some nitty-gritty chemistry, it might be best to focus on the significance of the ionic bond. This bond happens to be very strong (i.e. the sodium really wants that extra chlorine electron) but can be taken apart by a highly polar molecule. If only we had some polar molecules lying around here somewhere…
Oh wait! Water is polar! And we all know that salt loves to dissolve in water. Well, here’s why: the polarity of the water molecules (think of them as tiny little magnets with a positive and negative end) can rip apart the sodium chloride molecules leaving sodium and chlorine ions floating in suspension. If we were to boil the water away, the ions would re-join and form new salt crystals. You can even try this yourself by dissolving salt in water, boiling the water, and watching the new salt crystals form on the bottom of your pan. Just don’t do that with one of your nice pans.
Okay, I can just hear my chemistry friends pulling their hair out so I should probably clarify that salt molecules aren’t just a single sodium ion and a single chlorine ion but rather a crystalline matrix of the two ions.
Even with your plain eye, you can see that the micro structure of the sodium chloride atom reflects the macro structure of salt. In less fancy words, if you look at some grains of salt, you can see that they form a rough cubic structure.
We can break down salt (the edible kinds) into three categories:
Table salt: This form usually has small crystals (such that it can be poured easily out of a salt shaker) and additives to ensure the salt doesn’t clump. If you are going to leave your salt shakers out on your table, unsealed (as people are wont to do) then you need to ensure that the humidity of your home environment doesn’t cause the salt to cake. Thus table salt usually contains 1-2% of some anti-caking additive.
Iodized salt: Here we have a form of table salt with a home remedy mixed in. The idea of adding iodine to salt was that most people consume salt every day so why not add something beneficial to that mix? The iodine helps prevent thyroid issues and goiters. But, you know what? You can get iodine in a vitamin and not risk unwanted iodine tastes in your food.
I stopped using table salt years ago. Not because I’m worried about additives or the ever popular “toxins” but because the additives can alter the taste of the dish. No thank you!
Sea Salt: This form of salt is very expensive and comes with claims of exotic flavors and what not. Well, this is technically true because sea salt usually contains sulphur and magnesium. You know that nasty, rotten egg smell that happens at low tide? Yeah, that’s sulphur. To be honest, I don’t know why I would want that in my food. Plus fancy stores love to charge exorbitant prices for “natural” sea salt. Remember, salt is a molecule. No matter what form you buy it in, it’s a naturally occurring molecule. The only thing more “natural” about sea salt is that it usually contains extra stuff (magnesium, calcium, sulphur, and even traces of algae cells) which alters the flavor. Some cooks swear by the distinct flavors but I haven’t found a dish that yet warrants the extra bux.
And I should point out that there is not a single therapeutic benefit from sea salt that cannot be equally obtained by table or kosher salt (which are a hell of a lot cheaper). Remember back to the chemistry: salt is sodium chloride, table salt contains some iodine, sea salt contains some magnesium and sulphur. But all of these extra molecules are in trace amounts of < 3%. Not enough to do you any good.
Kosher Salt: My favorite! And not just because the great Alton Brown touts it as the best form of salt. Kosher salt contains no additives – all you get is sodium chloride. Plus, the crystals are typically much larger than the crystals you find in table or sea salt and thus easier to pick up. I much prefer this form since I know how sodium and chloride act. I don’t have to worry about any additives altering the taste of my food. Just plain, simple salt.
What is it about this simple little molecule that is so crucial to cooking? I’m not so sure I’m happy with the conclusions I was able to find on the internet (as many sites seem dedicated to heralding the evils of sodium) so I would welcome a biologist to comment on what I am about to present.
The tongue is able to taste 5 things: sweet, bitter, sour, savory (or, as the Japanese call it, umami) and salt (the Wikipedia article on taste also mentions “metalic” as a taste but that only comes from bad ingredients or bad cooking so we’ll ignore it). I’ll add in here that the former idea that certain zones of the tongue tastes certain things is a myth, the taste receptors are scattered all over the tongue. When certain molecules encounter certain receptors (say a glucose molecule to a sweet receptor), a signal is sent to the brain which tells it, “Hey! This is sweet!” The more receptors which are triggered, the more signals get sent to the brain and the more depth of flavor the food has. So the purpose of adding salt isn’t necessarily to make it taste salty but to trigger more receptors on your tongue. Trigger too many and the food will taste overly salty, trigger too few and the food will taste bland. They key is not to over salt and DEFINITELY do not rely on salt once the food has reached the table. In fact, take a second right now and go throw away your salt shakers. Don’t worry, I’ll wait.
Did you make your sacrifice to the garbage god? Okay, we can continue. Oh, stop pouting. Salt shakers are worthless since you can only use table salt – the holes are too small for kosher salt. Plus, just learn how to cook better and no one will want to mar your creations with heaps of salt. Just keep one thing in mind: if you are cooking a liquid food, such as a stew or soup, salt it right before you are ready to serve. If you salt to taste prior to cooking, evaporation will cause a higher salt concentration of NaCl by the time the food has cooked and the meal will taste too salty. Once this is done, you are quite hosed as it’s very difficult to salvage a meal which is too salty.
Fun fact: salt was so valuable as a food preservative during the time of ancient Rome that Roman soldiers were paid not in coin but in salt. The English word “salary” hence comes from the Latin word for salt, “sal”.
But let’s look at ways that salt is useful in the kitchen that don’t involve being eaten. We’ll start off with brines. Brining, usually done to poultry, is a way to keep the meat moist and flavorful through the cooking process. It is rather simple, take about a pound of salt, dissolve it in water, and dunk your whole chicken or turkey WITH THE SKIN ON into your salt water bucket. Whoa! Did you just read that right? Soaking a bird in salt water keeps it…moist? Doesn’t salt dry things out?
Let’s talk about osmosis – the idea that water can flow through a semi-permeable membrane to allow two bodies of solutes to reach an equilibrium concentration. If you are anything like I was when learning about brines, you probably thought, “If I put a non-salty heap of cells into a salty water bath, water will flow out of the cells in an attempt to bring the internal salinity into equilibrium with the external salinity which should leave my cells dry and salty.” But that is not necessarily how these poultry cells work. You see, if the poultry cells only held water and salt, a brine would be a terrible idea BUT these cells hold oodles of different solutes. The whole trick to brines is that the salt ions are small enough to permeate the cell walls but the solutes within the cells are too large to get out. First, salt ions flow into the cells to bring the internal salt concentration up to the external brine concentration. But this makes the cells much too salty since we have loads of water outside. So water flows in to saturate our mixture. In the end, we are left with a bird full of plump, water-filled cells – the perfect way to ensure your poultry won’t go dry before reaching the table. On a personal note, I used to despise turkey because my dear mother (whom I love very much) cannot cook to save her life. Her turkeys always came out so dry they would crumble. She won’t do brines because she is afraid of all the salt (as a side note, it has been shown that brines deposite a negligible amount of salt into the bird…but my mother doesn’t trust science 😥 I know, how did she produce me?) which is unfortunate because she could be the knockout of Thanksgiving.
Let’s say you just caught a nice mid-sized fish (a trout or a bass) and you would like to cook it whole. I have the perfect solution for you! Similar to an adobe oven, you can create a dome of salt around your fish to slow down the heat transfer from your oven and let the fish cook without losing any moisture. All you do is take a box of kosher salt, add about 0.5 cups of water and a couple egg whites, and mix everything together with your fingers. After the fish has been gutted, but not beheaded, stuff the empty cavity with some herbs and veggies. I chose to add dill, oranges, lemons, and fennel to my last salt dome. Lay your fish on a cookie sheet (I lined mine with parchment paper) and cover the entire fish, head to tail, with your salt mixture. You want to make sure the fish is entirely encased in the salt. Since the skin is still on the fish, none of the salt will penetrate to the inside. Bake it at about 350 F for 45-ish minutes or until the outside of the dome is starting to brown. Take the fish out and allow it to sit for another ten minutes (so much heat is retained in the dome that the extra ten minutes will complete the cooking). Then the fun part starts. Go grab your hammer and whack at the salt until it breaks into large pieces and can be removed. You want to whack it along the edges so it comes off in one piece. Underneath is the juiciest fish you have ever cooked whole.
I know, I know, I know. Epson salts aren’t actually salt at all. **EDIT** A chemist friend of mine pointed out that by chemical definition, a salt is “any ionic compound that isn’t an acid or a base.” I’ll add that the pluralized, “saltS” remains just silly. But a friend asked me to look into this and I thought it would fit nicely since many people are buying into the epson salt detox craze.
Epson salts, as I mentioned are a misnomer as its chemical composition is MgSO4 or a magnesium atom, a sulphur atom, and four oxygens. So, absolutely nothing in common with actual salt at the molecular level. However, this mineral can form large crystals in the presence of water which look similar to salt crystals and, like NaCl, epson salts dilutes in water easily. A more proper name for epson salts is magnesium sulphate and we will be using this for the remainder of the post. The woo crowd has adopted magnesium sulphate since it is a naturally occurring mineral but, as I’ve said time and time and time again, natural does not mean safe. However, in this case, it turns out that magnesium sulphate isn’t dangerous.
In fact, magnesium sulphate is legitimately beneficial in certain medical applications. Whaaaaaat?! Did I just admit that the naturalists had something right? Well, a bit. As it turns out, the naturalists are touting the WRONG benefits of magnesium sulphate but I’ll get to that in a minute. Hey, a post of mine wouldn’t be complete without debunking some pseudoscience, now would it?!
First, let’s talk about what magnesium sulphate is good for. Say you are unlucky enough to have hypomagnesemia (or a severe deficiency of magnesium in your blood). An injection of prescription drugs which include, among other things, magnesium sulphate may be just the thing you need. That and a gatorade.
Where magnesium sulphate doesn’t work – or at least there is no good reason to believe they work: baths or pain alleviation. Here’s the thing, magnesium ions can’t get past our skin and neither can the sulphates. This is been rather extensively tested by having test subjects bathe in a “detoxing” magnesium sulphate bath. (The word “detox” should be your first clue that it’s total bunk but we wouldn’t be good scientists if we didn’t check things out, now would we?) Since the baths failed to raise blood concentrations of magnesium or sulphate, smearing magnesium sulphate cream was tested. Even with direct application, no effect was measured. None. Zip. Nada. I’m not going to go into every reason why magnesium sulphate does absolutely nothing beneficial to the body in bath form and certainly doesn’t “detox” or relieve pain but I will direct you to a wonderful website which answers every magnesium sulphate question you might have. So, as a take away MAGNESIUM SULPHATE OR “EPSON SALTS” HAVE ABSOLUTELY NO POSITIVE IMPACT FOR THE BODY WHEN USED IN A BATH. IT DOES NOT AID IN “DETOXING” AND DOES NOT ALLEVIATE PAIN. At least there have not been any studies which have shown positive results and many which have shown zero efficacy.
But, I’ll tell you what, show me repeated double-blind studies that show substancial evidence for pain relief or “detoxing” from epson salt baths and I will eat my words. Tell me, “but I tried it and I felt better,” and prepare for a lengthy lecture about how anecdotal evidence isn’t worth jack. I’ll briefly explain why. Scientific conclusions must arise from controlled studies, must be unbiased, and must be made through logic, not emotion. I touch on this idea in an earlier post of mine which you can read here. Saying, “I felt better,” is subjective. How much better? How did you control your experiment How are you sure nothing else could possibly be responsible for your pain alleviation? Was your sample size larger than just yourself? Anecdotal evidence arises when none of these questions are able to be answered – which is why it frustrates scientists to no end when people justify non-effective remedies with the excuse, “but I felt better after I [insert pseudoscience here] therefore it must have worked.”
Turns out, without salt, charlatans would have one less way to scam your money away. Detox foot baths refer to the practice of placing one’s feet into buckets of water and allowing [INSERT SCIENCE-SOUNDING WORDS HERE] to take place. Toxins are drawn out of your body as evidenced by the black flakes found in the bottom of the bath and discoloration to the water usually accompanied by a chlorine smell. I first learned about this practice when my cousin, who was suffering from Lyme disease, started lauding the amazing miracle cure he found at, and I kid you not, his local mall. The real killer was was that his parents were already suffering financially from paying for the real medical care he received. Having taken basic high school chemistry, my immediate thought was, “that…sounds like a precipitate not an effect of osmosis, to me.” I was right. And for the financial and emotional damage those criminals did to my family, anyone hawking detox foot baths can shove them straight up their asses.
But don’t take my word for it, you can construct a detox foot bath yourself and prove that nothing other than a simple chemical reaction involving salt and iron is taking place. In fact, you can replicate the black flakes (you know, the “toxins”) without even putting any part of your body in the water. These are the worst types of scams: the type where the person selling the scam knows full-right well they are selling a hoax. If there is a hell, may Sagan damn them straight there.
I really, really, really don’t like pseudoscience. In case you haven’t noticed.
Anyway, back to the experiment. Detox foot baths claim that “ionization” draws toxins out of your body. As we learned above, ionization is a result of dissolving salt in water. Any time you have a salt-water mix, you have ions. Knocks the magic right out of it, don’t it? Then they “charge the ionized solution” which means they apply a small current to the water. Since you are quite literally being electrocuted, you feel a tingly sensation. The dissolved salt helps conduct the electricity so at least we know they have taken middle school chemistry. Now to get the electricity into the water, the perpetrators must submerge a couple of electrodes (nodes which allow the electrons to flow into and out of the water, nothing fancy). What are these electrodes made of? Various types of metal (copper, iron, nickel). And what happens when we place various types of metal in salt water? Aaaah, the picture starts to come together. The discoloration of the water and black flecks are nothing more than rust. I’m sorry. Really, I’m so sorry if you, the reader, were ever scammed into one of these. But that is the truth. Not only is your skin impermeable to just about everything except water (including toxins), when put through trials, the left over water revealed nothing but salt and rust.
You can prove this to yourself by hooking up a car battery to two lengths of copper wire which end in two non-galvanized nails (since galvanized nails don’t rust, just go for the cheap nails, the charlatans sure do). Submerge those nails in a bath of salt water. Also, please be careful, I don’t want anyone electrocuting themselves. Stay grounded. Literally. After about 10 minutes, you will see all the “toxins” you care to see. And the smell? Remember the other ion produced when NaCl dissolves? Yep. It’s chlorine. The smell is nothing more than the chlorine ions evaporating. The electricity just helps speed things up a bit which is why you don’t smell chlorine in your kitchen.
tl;dr DO NOT WASTE MONEY ON DETOX FOOT BATHS
“But salt is soooooooo bad for you, aren’t you concerned about your sodium intake???!!!”
Not really. Our bodies need sodium to survive. You know what’s in those “Smart Water” sports drinks everyone loves? Yeah, salt. Or, by their fancier name, electrolytes. And now I present my favorite clip from one of my all-time favorite movies:
Seriously, WATCH THIS! And then go to Netflix and watch Idiocracy. Immediately. Or, if you are lucky enough live in a free country like Canada, just borrow it from the internet 😉
I won’t argue for a second that too much sodium is a terrible idea. It can lead to heart disease, lethargy, kidney disease, or stroke. But it is necessary for brain function. Just like how the sodium ions allow for electricity to flow in and out of the detox foot baths, sodium helps grease the electrical pathways in your nerves among other things. It is so necessary, in fact, that our brain is hard-wired to crave it. Have you ever just needed a bag of chips?
But, I’ll tell you what, cook for yourself and don’t salt your food after cooking, and you will find yourself with just the right amount of sodium. The real issues with high sodium come from eating preserved foods. Salt is the world’s oldest, cheapest preservative. Next time you think about buying that box of microwaveable kung pow chicken, take a look at the sodium content. Your eyes will surely bulge when they see how much salt is in one of those suckers.
So don’t worry about putting a bit of salt into your food to enhance the flavor. As long as you keep an eye on the food you don’t make, you won’t find yourself in much trouble.