Heat changes molecules

Why is this interesting and why should we care?

You ever try to grow a seed after heating it? Everyone knows that if you heat something too much you kill it. We all take that for granted. We learn that at a young age and simply don’t question it. Well, that is what we will do now.

Why did heat kill the seed?

And, probably more important:

Did the heat kill the seed?

Both questions are kind of puzzling. Why would anyone question how the seed died?

To understand this a bit better, let’s look at the first signs that a seed provides to indicate that it is alive. That process has a well known name, germination. Here is what the Wikipedia has to say about germination:

Germination is the process in which a plant or fungus emerges from a seed or spore and begins growth. The most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm.

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Germination is the growth of an embryonic plant contained within a seed; it results in the formation of the seedling.

So, if the seedling can germinate, we know that the seed is alive. I know this next part is going to sound really simple, but what makes a seed germinate? Yes, I know. This is another one of those things that just about everyone also takes for granted. At the same Wikipedia link, we see:

Seed germination depends on both internal and external conditions. The most important internal factors include temperature, water, oxygen and sometimes light or darkness.

As it turns out, the requirements needed for that little seedling align pretty well with what we humans need to stay alive. But let’s continue to focus on the seedling.

If you look closely at what the Wikipedia says about the effect that water has on germination, we find some interesting points:

Water – is required for germination. Mature seeds are often extremely dry and need to take in significant amounts of water, relative to the dry weight of the seed, before cellular metabolism and growth can resume. Most seeds need enough water to moisten the seeds but not enough to soak them. The uptake of water by seeds is called imbibition, which leads to the swelling and the breaking of the seed coat. When seeds are formed, most plants store a food reserve with the seed, such as starch, proteins, or oils. This food reserve provides nourishment to the growing embryo. When the seed imbibes water, hydrolytic enzymes are activated which break down these stored food resources into metabolically useful chemicals.^[2]

So, if the seed is alive, when it takes in water and oxygen at the right temperature and with the correct amount of light, enzymes are activated which break down the stored resources into usable building blocks that the plant can use to grow.

What I find interesting is that the Wikipedia can always take a simple subject and confuse it with a lot of big words. What are hydrolytic enzymes? And what are metabolically useful chemicals?

From this link, we find a hint regarding what a hydrolytic enzyme is:

In biochemistry, a hydrolase is an enzyme that catalyzes the hydrolysis of a chemical bond.

Looking closer, Hydrolysis is:

Hydrolysis is a chemical reaction during which molecules of water (H₂O) are split into hydrogen cations (H⁺) (conventionally referred to as protons) and hydroxide anions (OH⁻) in the process of a chemical mechanism.^[1][2] It is the type of reaction that is used to break down certain polymers, especially those made by step-growth polymerization. Such polymer degradation is usually catalysed by either acid, e.g., concentrated sulfuric acid (H₂SO₄), or alkali, e.g., sodium hydroxide (NaOH) attack, often increasing with their strength or pH.

Hydrolysis is distinct from hydration. In hydration, the hydrated molecule does not “lyse” (break into two new compounds).

Something worth noting here is that when something goes through hydrolysis, it is a chemical reaction that splits down certain polymers. Also, form the seed perspective, it’s using enzymes to perform this function. (What we don’t cover here is the reference to pH. That is a article for another day!) Yet, what is a polymer?

A polymer is a large molecule (macromolecule) composed of repeating structural units typically connected by covalent chemical bonds. While polymer in popular usage suggests plastic, the term actually refers to a large class of natural and synthetic materials with a wide variety of properties.

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Because of the extraordinary range of properties accessible in polymeric materials,^[2] they play an essential and ubiquitous role in everyday life^[3]—from plastics and elastomers on the one hand to natural biopolymers such as DNA and proteins that are essential for life on the other.

So the addition of water to the seed enables it to put its water sensitive enzymes to work breaking down the stored protein or other long molecules that have covalent chemical bonds. The seed can convert long macromolecules and proteins into what it needs to grow by simply applying water based enzymes.

As a reminder:

 A chemical bond is an attraction between atoms or molecules and allows the formation of chemical compounds, which contain two or more atoms. A chemical bond is the attraction caused by the electromagnetic force between opposing charges, either between electrons and nuclei, or as the result of a dipole attraction. The strength of bonds varies considerably; there are “strong bonds” such as covalent or ionic bonds and “weak bonds” such as dipole-dipole interactions, the London dispersion force and hydrogen bonding.

If you remember from a previous article (Is food another form of light) you’d remember that when the chemical bonds break down, the molecules give off electromagnetic energy (light) in the process. Thus, light is part of the growing process – from the inside out!

So, if I’m following this correctly, the enzymes are the molecules that first go to work in the germination process that will eventually show up to us humans as a growing plant.

Makes sense that we look at enzymes:

Enzymes are proteins that catalyze (i.e., increase the rates of) chemical reactions.^[1][2] In enzymatic reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts them into different molecules, called the products. Almost all processes in a biological cell need enzymes to occur at significant rates. Since enzymes are selective for their substrates and speed up only a few reactions from among many possibilities, the set of enzymes made in a cell determines which metabolic pathways occur in that cell.

Like all catalysts, enzymes work by lowering the activation energy (E_a^‡) for a reaction, thus dramatically increasing the rate of the reaction. Most enzyme reaction rates are millions of times faster than those of comparable un-catalyzed reactions. As with all catalysts, enzymes are not consumed by the reactions they catalyze, nor do they alter the equilibrium of these reactions. However, enzymes do differ from most other catalysts by being much more specific. Enzymes are known to catalyze about 4,000 biochemical reactions.^[3] A few RNA molecules called ribozymes also catalyze reactions, with an important example being some parts of the ribosome.^[4][5] Synthetic molecules called artificial enzymes also display enzyme-like catalysis.^[6]

Enzyme activity can be affected by other molecules. Inhibitors are molecules that decrease enzyme activity; activators are molecules that increase activity. Many drugs and poisons are enzyme inhibitors. Activity is also affected by temperature, chemical environment (e.g., pH), and the concentration of substrate. Some enzymes are used commercially, for example, in the synthesis of antibiotics. In addition, some household products use enzymes to speed up biochemical reactions (e.g., enzymes in biological washing powders break down protein or fat stains on clothes; enzymes in meat tenderizers break down proteins, making the meat easier to chew).

Looking a little deeper into the enzyme link at Wikipedia:

Like all proteins, enzymes are made as long, linear chains of amino acids that fold to produce a three-dimensional product. Each unique amino acid sequence produces a specific structure, which has unique properties. Individual protein chains may sometimes group together to form a protein complex. Most enzymes can be denatured—that is, unfolded and inactivated—by heating or chemical denaturants, which disrupt the three-dimensional structure of the protein. Depending on the enzyme, denaturation may be reversible or irreversible.

There they go using another collection of relatively unknown words.  Let’s look at denatured:

Denaturation is a process in which proteins or nucleic acids lose their tertiary structure and secondary structure by application of some external stress or compound, such as a strong acid or base, a concentrated inorganic salt, an organic solvent (e.g., alcohol or chloroform), or heat. If proteins in a living cell are denatured, this results in disruption of cell activity and possibly cell death.

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When food is cooked, some of its proteins become denatured.

Hey, that is the link I was looking for! We should eventually come back to that.

First, let’s look back at our question: did the heat kill the seed? Logically, it would seem that the heat denatured the proteins that make up the enzymes that are used to break down the stored resources that the seed needs to grow.

Looking at this a different way, after applying heat, the seed has no means of convert the stored resources (proteins and carbohydrates) into useful building blocks for growth. Because of this, the seed is effectively locked in a state of not being able to use its energy reserves.

Ultimately, the heat killed the seed. But why the heat killed the seed has to make you wonder. If heat can denature the proteins that are needed by the seed to life and grow, what kind of ramifications does it have on the human body? Doesn’t the human body need enzymes – just like the seedling does? More importantly, if heat can denature enzymes, which are protein molecules, it would hold that heat would change all types of protein molecules.

We see what heat does to proteins, what about carbohydrates?

Let’s look that up:

A carbohydrate is an organic compound with the general formula C_m(H₂O)_n, that is, consists only of carbon, hydrogen and oxygen, the last two in the 2:1 atom ratio. Carbohydrates can be viewed as hydrates of carbon, hence their name.

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Monosaccharides can be linked together into what are called polysaccharides (or oligosaccharides) in a large variety of ways. Many carbohydrates contain one or more modified monosaccharide units that have had one or more groups replaced or removed. For example, deoxyribose, a component of DNA, is a modified version of ribose; chitin is composed of repeating units of N-acetylglucosamine, a nitrogen-containing form of glucose.

And from the polysaccharides link we find:

Polysaccharides have a general formula of C_x(H₂O)_y where x is usually a large number between 200 and 2500. Considering that the repeating units in the polymer backbone are often six-carbon monosaccharides, the general formula can also be represented as (C₆H₁₀O₅)_n where 40≤n≤3000.

Yet these longer molecular structures don’t taste all that great, nor do the digest readily until they are broken down into smaller pieces. Some enzymes can perform this work, but the fastest process is heating. The heating process breaks the chemical bonds that attach the longer molecules into smaller ones.

This can be seen in the simple process of cooking a potato. Does it taste better raw, or cooked? Anyone can tell you that it tastes sweater after cooking. That’s because the longer starch molecules have been broken down into simpler sugars with register as sweet to the taste budds.

What’s also interesting is that plants have developed molecules that humans have a hard time with. Specifically, if we look up Cellulose, we find:

Cellulose is an organic compound with the formula (C₆H₁₀O₅)_n, a polysaccharide consisting of a linear chain of several hundred to over ten thousand β(1→4) linked D-glucose units.[2][3]

Cellulose is the structural component of the primary cell wall of green plants, many forms of algae and the oomycetes. Some species of bacteria secrete it to form biofilms. Cellulose is the most common organic compound on Earth. About 33 percent of all plant matter is cellulose (the cellulose content of cotton is 90 percent and that of wood is 40-50 percent).

It’s a really long polysaccharide that forms the cell wall in plants. It’s something that we don’t digest well. Cows and horses do a much better job handling this molecule with the help of microbes. Yet, the human solution to getting around this problem is to cook it.  Applying heat breaks apart the cell wall which makes what’s inside the cell available to the body. Yet heating also denatures other elements of the cell.

So, what do we do?

It would seem that heating destroys key elements of our food. Elements like enzymes that we need to break down other molecules. At the same time, our bodies can’t get to all the ‘food’ in what we eat unless we can get past the larger polysaccharides that block our digestive way.

If we want the best of both worlds here, we’re going to have to get to what’s in the cell without ingesting the larger indigestible molecules. Off hand, I can think of two techniques:

• Juicing

Here we simply squeeze what’s inside the cells out. If done with little friction, which causes heat, the results should be pure and highly digestible by the body.

• Blending

Similar to juicing, a good blender will apply enough force to the cells to get them to break apart rendering a mixture that still contains the fibrous material along with the ‘nectar’ found inside the cells.

Both of these techniques seem like great alternatives then heating.

This investigation still leaves a number of unanswered questions.

If heating denatures proteins (destroys them) and you consume them. Can your body still use them effectively? Do these fractured pieces of molecules find function in the body? Or, do they create a situation like looking for an intact glass in a pile of glass fragments? (A nearly impossible task for surviving enzymes.) Also, might the body actually use the denatured proteins thinking that they were the real intact versions? What might this cause?

The more I learn about how heat changes molecules, the more I ask myself is it really worth consuming denatured food? Are there other alternatives like juicing and blending – or simply eating the food unaltered? What might be the best choice?

I guess I’m going to have to investigate whether or not the body can create its own enzymes and how that is done. On top of that, I’ll have to look into mucus and see what that’s made of. I heard it was undigested proteins – the above information could support that idea. Pausing and reflecting on the above, I can understand why so many people have runny noses!

The real question is what are you going to do? It seems pretty clear to me that we should be consuming foods with unaltered molecular structures. I’m going to make it a point to do so.  What about you?