The fizz that can fizzle and frazzle

Forget commercial sprays and soap – club soda is one of the all-time best and cheapest carpet cleaners around. Not that this household tip is any great secret, but when it comes from one of Vancouver’s top wool carpet cleaners you can bet it works (just make sure you blot, don’t rub).

We’ve been using club soda to spot clean our carpets for years so when the stuff comes on sale we stock up on the family-sized bottles. Having them on hand for a party where you’re serving red wine makes you feel as secure as having a big fire extinguisher in your kitchen.

But we don’t use club soda for much else – maybe mix it with OJ when someone has a cold and it feels good to have fizzy carbonation scratching your throat. So the bottles tend to hang around for a while.

Still, I was pretty surprised that the last one we opened could barely muster a pffffft it was so flat. Of course, because all the bubbly effervescence was bust it didn’t do such a great job of cleaning up the combo splotches of barbecue sauce/meat drippings trailing from the deck to the kitchen.

The real mystery was that we hadn’t had it that long, maybe a few months. By contrast, I swear my dad stored big beautiful dark green bottles of Canada Dry in our basement in Edmonton from one Christmas to the next and the fizz stayed fizzy.

Everybody at our barbecue that night just laughed when I told them I thought that the old glass pop bottles with the crimped metal caps better preserved carbonation. To redeem myself the next day, I tried to check out my theory on the Internet. It was a tough search, but finally I struck gold with good old-fashioned hard copy: Robert L. Wolke’s book, What Einstein Told His Cook .

Even Wolke, who is professor emeritus of chemistry at the University of Pittsburgh, had a tough time convincing the people at Coca-Cola to look into the idea that plastic pop bottles don’t hold carbonation as well as glass. But lo and behold, they were able to confirm it once they investigated for themselves – and hey, they’re the experts, selling some 47 per cent of all the pop sold worldwide, more than twice as much as their nearest competitor, Pepsi.

This is their conclusion: Glass isn’t at all porous. On the other hand, plastic pop bottles, which are made of polyethylene terephthalate or PET, are slightly permeable to carbon dioxide gas so enough can leak out to take the sparkle out of your fun. Apparently that’s at least one of the reasons why you see expiry dates on screw caps on pop bottles these days, not that I’ve ever checked them, but I will now.

The "best-by" periods vary, depending on content. In the case of Coke, you’d better drink your Classic within nine months of it rolling off the assembly line. On the other hand, Diet Coke only has a shelf life of three months because the aspartame in it loses its sweetness over time.

So what’s the best way to keep your pop – and I don’t mean your dad – from going flat? According to Wolke, keep it cold, for the colder a liquid is, the more carbon dioxide it can hold. Ironically, this phenomenon inverts on itself for the people in the Norwegian fishing town of Tromso, 225 miles above the Arctic Circle, where retailers keep their Coca-Cola not in coolers but in "warmers" to keep it from freezing.

Essentially, pop in the fridge can hold twice as much CO ₂ as pop at room temperature. That’s why you get a giant pffffft when you open a can or bottle of warm pop (or beer): there’s a lot more gas in there than is able to stay dissolved in liquid at room temperature.

Of course, since you were a kid you knew if you didn’t finish your pop you had to put one of those rubber stopper thingies in it or it would go flat. Once it did, go flat that is, I always thought it tasted way more sickening than could be accounted for by the fact the effervescence was gone.

Once again, Professor Wolke comes to the rescue with a perfectly logical explanation. Indeed, there is more to our taste buds’ disappointment in flat soda pop than the disappearance of those tiny bubbles that deliver the tingling sensation we all like – or at least we do after a certain age: the tongue and delicate lining of our mouths have to evolve to a certain level before we perceive it as a pleasant sensation.

Here’s the difference: carbon dioxide dissolved in water creates carbonic acid, a sour acid that delivers a nice tartness to counterpoint pop’s heavy sugar content (the average can of pop contains 8 to 10 teaspoons of sugar). No wonder pop tastes so yucky after the fizz fizzles.

But maybe keeping the fizz in a half-drunk bottle is way too outré to even worry about – I mean, is there anybody besides me in our pop-guzzling world who can’t finish a whole bottle or can, and I’m talking individually-sized bottles here? Each Canadian is now drinking about 120 litres of pop every year, more than double the 55 litres/year we drank in 1972. And in the U.S. – top nation for pop consumption – the average person drinks 140-plus litres every year. And people wonder why so many folks are fat and diabetic?

As for those little pump dealies that are supposed to pump the CO ₂ back into your half-used pop bottle, forget it. All you’ll pump into the bottle is air, not carbon dioxide, which in no way improves the effervescence.

While we’re talking about all the carbon dioxide we find in pop here, and how much is escaping from our leaky plastic pop bottles, let me say this: you’re maybe not so crazy if you’re wondering about the impact on global warming of all this extra CO ₂ .

Wolke has calculated that in one year Americans alone drink around 15.2 billion gallons of pop and 6.2 billion gallons of beer. That would add up to 800,000 tons of carbon dioxide. Sheesh.

Given that global warming depends on the sun’s radiation not being able to escape the Earth’s atmosphere and that carbon dioxide is one of the big absorbers of infrared ration, my advice is let’s move back to glass pop bottles and keep those tops well-stoppered. I don’t want all those people in Norway to give up their pop warmers.