Hey everybody, welcome back to Land Back Home 5, the podcast where we take the questions you always wanted to ask and talk about them in a way that's easy to understand. We are your hosts, I'm Tim. And I'm Kevin. So Kevin, today we're talking about soda, and let's start with this interesting question.
If you drink Coca-Cola or Pepsi in an aluminium can, it tastes kind of different to Coca-Cola or Pepsi from a glass bottle, or from a plastic bottle for that matter. Why is that? Yeah, it's a pretty funny effect, right? So the aluminum cans, they have a polymer lining that can actually absorb some of the soda's flavors, potentially making it taste milder.
And if you are drinking your soda from a plastic bottle, the soda's flavor may actually be altered by some of the acetyl-ohyde in the plastic transferring into the drink. Look, since glass bottles are basically inert, they'll deliver a product very close to the original intent. However, the metal taste that some people note from soda in cans may have more to do with their sensitivity to metal, and they're tasting the can basically as they put it to their lips, not a metallic taste that's actually present directly in the cola. There's a great Reader's Digest article on this, which we can reference in the show notes.
Hmm, okay. Now, isn't there also a different level of fizziness in different materials of sodas? Fizziness is also very important to the soda-drinking experience. So the amount of carbon dioxide, which is what causes the fizziness in these red bridges, it's very quality-controlled and set to be within certain ranges.
But the material they're stored in affects what levels need to actually be set. So glass and aluminum cans have lower porosity. And what this means is it makes them pretty good, but pretty good packaging materials for sodas, since they can retain the gas volumes in soda. I see.
In other words, glass and metal prevents the CO2 from escaping. Exactly. And that's important for maintaining that nice, fresh, biting taste. On the other hand, plastic or PET bottles have higher porosity than glass or aluminum, which means carbon dioxide can easily escape making the soda kind of bland.
So what they do to compensate for this is they deliberately increase the gas volumes in PET products. So a freshly bottled PET soda has a very strong bite due to the high volumes of CO2 still in it. Why is canned soda so much colder than bottled soda? It feels like if you put the two of them both in the refrigerator for the same amount of time, they should be the same amount of cold.
But a can always taste much colder. So when you touch something and it feels cold, what's really happening is that's because heat is leaving your body and flowing into the cold object. So this is called thermal conduction in science. And different materials conduct heat at very different rates.
And this is measured in something called watts per meter Kelvin. And the higher this number is, the thing to know is that the higher this number is, the faster a material conducts heat. Okay? So glass here has a thermal conductivity coefficient around 0.8 watts per meter Kelvin, while aluminum is around 239 watts per meter Kelvin.
You know, 0.8, 239, that's a pretty huge difference. So if you measure the temperature of both liquids right out of the fridge, they will be the same temperature. But the one in metal feels colder in your hand because it is rapidly taking heat from you faster than the one in the glass bottle. And what this means is that the drink in the glass bottle will actually stay colder for a longer period of time, since it will take longer for the liquid to absorb the same amount of heat.
Now, the age-old question is, what is it about Coca-Cola that makes it so hard to replicate? The flavor of lemon, lime, grape, orange, etc., those sodas, they seem to be fairly consistent. But the off-brand Coca-Cola flavors never really taste quite the same. And, you know, it's not just about ingredients.
The process is extremely important, too. You know, taking sugar turned into caramel, the total length of time spent heating the sugar, the total joules, and the temperature curve, you know, at which point there were changes in heating, it directly affects the flavor and texture. You make it too hot and it tastes burnt, or too slow and it's all kind of runny. So it's actually a lot about the process of manufacturing a drink.
It's just as important as the ingredients and way harder to figure out, especially at that scale. How can soft drinks like Coca-Cola Zero have almost zero calories in them? Is there some detriment to your health because of the lack of calories? So Coke Zero has something called aspartame in it, which is an artificial sweetener.
And what this means is that the molecule aspartame has this 3D shape that our taste buds recognize as being sweet, kind of similar to, you know, glucose, sucrose, fructose, all the other sugars. But unlike these regular sugars, it is in fact a molecule that does not occur in nature. So our bodies do not have the proper enzymes to break it down. Thus, it passes through our bodies undigested without absorbing any calories.
For any reason, humans can't subsist on grass. Our bodies just do not have the enzymes necessary to process cellulose, which is the main sugar polymer, a string of sugars to connect together in plants. So does that make it harmful to your body then? Not actually a problem.
Other than that, nobody can know for certain. But food additives such as aspartame and sucrose are some of the most studied molecules, almost on the level of drugs. There are no immediate health problems associated with artificial sweeteners. However, there are myriad studies cropping up recently proposing certain long-term health effects that may be tied to sweeteners.
Ah, that's right. We did do an episode, I think, on artificial sweeteners earlier this year. We did indeed. It was ELI-5 artificial sweeteners.
Good or bad for weight loss. That's right. That was a great January topic. Did you learn something new?
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