I know the general consensus is “It’s water! It doesn’t go bad!”
But isn’t available water content the main factor in spoilage?
If anything it seems water would be VERY susceptible to culturing something nasty.
If there are no nutrients in the water nothing will grow there. I believe they are more worried about something in the plastic of the bottle leeching into the water over a long term.
If plastic bottles leached potentially harmful substances that easily they would have been class-actioned out of existence long ago.
Personally, I think that would have been a good thing- I have always thought anything tastes better out a glass container than out of a plastic one. Soft drinks are a prime example. It is so sad that a third generation of children has been born who will never know what a 6.5 oz glass bottle Coke tastes like.
It doesn’t have to be a “harmful substance”. As you said, over tme liquids in plastic tend to taste worse. The manufacturer doesn’t want you to equate their product with nastiness, so they put on a “Best if used by” date (which they may call an expiration date).
But isn’t available water content the main factor in spoilage?
It’s only half of the story. You need water AND food to survive. Sugar without water = sweet rocks. Sugar with water = growth medium.
I have many years of experience in the plastic-bottled water industry. The reason for the best-before date (it’s never an “expiration date”) is because the plastic bottle breaks down over time.
Plastic bottles are made of long-chain polymers – primarily polyethylene terephthalate. Using heat and mechanical stretching, the chains are aligned to form a strong, thin and clear plastic. Exposure to UV light can energize or eject electrons from the chemical bonds in the polymer molecules, which causes the bonding characteristics to change (and break). As these bonds break, the polymer can weaken even if no monomer molecules end up floating around in your water.
As the bonds break, the bottle actually starts to deform (it doesn’t hold itself in a perfectly cylindrical shape any more, and becomes oval, and sometimes doesn’t stand straight). As manufacturers try to minimize the amount of plastic in each bottle, the walls get thinner, and they start to spring leaks quicker. During my time at the bottling plant we were considering changing from 9.1g/bottle to 8.1g/bottle, and had to drop our best-by date from 24 months to 18 months.
As for the water itself, it’s disinfected with UV and then again with ozone. The ozone’s essentially dissipated within twenty minutes of bottling, but lasts long enough that any living organisms that found their way inside the bottle or survived the UV will die. If somehow a bottle did become contaminated it would be visibly spoiled long before the best-by date was reached.
That’s not necessarily true. For a long time we made drinking bottles out of polycarbonate plastics. (Even baby bottles – which we’d heat up in the microwave – were made of polycarbonate.) The monomer in question was bisphenol-A (BPA) which is an endocrine disruptor. They never got “class-actioned out of existence,” rather, they were removed by manufacturers as knowledge spread and consumers stopped buying them.
Also, there are potentially harmful substances used in the manufacture of PET, which we use in food containers worldwide. Antimony, a toxic heavy metal, is used as a catalyst in PET manufacture and traces may be left behind. Ethylene and terephthalic acid, the monomers of PET, can also be released by PET as it ages and is exposed to UV light. Acetaldehyde is formed when the PET is heated in the blow moulding process. These aren’t particularly unsafe (so far as we know – acetaldehyde, at least, is naturally-occurring in fruits) but they can add off flavours and are mild irritants. Any recycled PET implies a non-zero risk of benzene contamination.
But we still use PET. Everywhere, in every kind of food packaging. Maybe not safe, but at least it’s cheap.
Ah, sweet memories. One of my favorite things in the world was an ice cold coke in one of those small, green bottles. It’s amazing to even think that we could be satisfied with less than a big gulp amount of soda.
I am not a big coke fan, but that stuff in the glass bottles was the best tasting soda on the planet.
Can you please invent something that imitates the old green coke bottles, please? And hurry!
How about new glass coke bottles from Mexico?
(You’ll have to put a filter over your lights to make them green though…)