Acidity in drinks
December 20, 2010 7:50 AM   Subscribe

A drink, some flavour and some bubbles. So why the acid?

Most carbonated drinks contain acids. Acid is bad for teeth though Coca-cola do seem evasive on this. The right amount of alkali can neutralise acid and render it harmless in comparison to the acid. So why not add alkali to the drink?
It is not beyond technology for the opening of a can / bottle to introduce an alkali if preservation to the point of consumption is an issue and the drink companies are best placed to know exactly what to use. Maybe it's taste? Or is it that such a move would acknowledge that previously damaging nature and open them to being sued? Is the reason firmly commercial or would they put some sort of "Of course acid is better for you" spin for whatever reasons.
If you wanted to neutralise a glass of a carbonated beverage what would you use and how? (Can you even buy liquid alkali apart from as an oven cleaner?) Is the potential for damage from overdoing the alkali in a drink that much greater than acid?

*Note - this is not about dental hygiene. It's just about the liquids before they get to the mouth.
posted by episodic to Health & Fitness (9 answers total)
 
It would taste awful. Acids in proper amounts taste good; that's why people eat citrus fruits. Try adding half a teaspoon of baking soda to your Coke and see how you like it.
posted by Faint of Butt at 7:55 AM on December 20, 2010


a) Neutralizing an acid with a base results in a salt. Gross.

b) The CO2 put into the drink becomes carbonic acid.

c) It tastes way better if it's tangy+sweet instead of just sweet.

If you wanted to neutralise a glass of a carbonated beverage what would you use and how?

Baking soda, I'd reckon, would be the easiest to find. If you want it a liquid, just dissolve it in some water beforehand. But, it's going to cause your drink to foam up like crazy (thereby going flat in the process), is going to taste salty, and so is not likely to be very appetizing after you're finished.
posted by Netzapper at 7:57 AM on December 20, 2010 [3 favorites]


In your link, Coca-Cola doesn't seem evasive to me. Rather, it looks like they're pointing out that statements like "acid is bad for teeth" are gross oversimplifications. Many foods we consider "healthy" are, indeed, acidic. Coke is not health food, but acidity is not a significant part of the problems with it.

I would guess it's mostly about flavor. Acidity cuts sweetness, so adding acid allows them to up the sugar content, and sugar is a major part of what people crave about soft drinks.
posted by jon1270 at 8:01 AM on December 20, 2010


this is not about dental hygiene

Then what is this about? You specifically have tried to imply that acidic drinks are damaging. Acidic drinks are acidic because that's part of the nature of their flavor. Acidic isn't an inherent negative. As far as pH goes, stomach acid is much more acidic, and the saliva in your mouth does an excellent job of neutralizing things in the long term.

The entire idea of colas, or specifically Coca-Cola, being acidic to the point of being harmful is the stuff of urban legend and rumor. You could make the same question asking why foods that are very basic do not have an acid added to render them neutral, or why other acidic drinks or foods are not rendered neutral. Have you ever had a vinaigrette salad dressing?
posted by mikeh at 8:33 AM on December 20, 2010 [2 favorites]


The phosphoric acid in coca-cola adds sour notes to the taste and acts as a preservative. The low pH is probably the primary property that keeps microorganisms from growing in there.

If it were neutral, there would be no sour elements to the flavor: it would probably taste pretty bad. It would also probably require additional chemical preservatives.

Is the potential for damage from overdoing the alkali in a drink that much greater than acid?

The "danger" here is negligible.
posted by mr_roboto at 11:17 AM on December 20, 2010


The acidity of Coca Cola is not what makes it bad for your teeth, really. It's not even all THAT bad for your teeth, unless you were to walk around all day gargling and swishing it every 10 seconds. Your teeth probably get exposed to more acid when you eat an orange, what with all the chewing.

It's the acidic byproducts of bacteria feeding on sugar that cause tooth decay, and they need something to stick to your teeth (like starch), or a constant sugar bath (like if you suck on hard candy or chew gum with sugar). Beverages are swallowed pretty quickly and don't usually represent the biggest risk factor.
posted by overeducated_alligator at 12:24 PM on December 20, 2010


mikeh: "The entire idea of colas, or specifically Coca-Cola, being acidic to the point of being harmful is the stuff of urban legend and rumor. You could make the same question asking why foods that are very basic do not have an acid added to render them neutral, or why other acidic drinks or foods are not rendered neutral. Have you ever had a vinaigrette salad dressing?"

Acid erosion is a real problem, and it has nothing to do with urban legends about putting teeth in glasses of Coke. Some people are more susceptible to it than others eating a similar mixed diet, some people eat a lot of sour and sticky foods and put themselves at greater risk, and some people make errors, like habitually brushing their teeth vigorously immediately after eating, that will help wear off temporarily softened dental enamel if their snack or meal was relatively acidic.

Eating or drinking any relatively acidic item -- orange juice, sports drinks, regular and diet soda pop, tomatoes, vinaigrettes, to list a few -- several times a day seems to expose you to the most risk. If you exhibit early signs of erosion, you should try minimize exposure to such foods, eat them with more alkaline foods, like cheese, and resist brushing your teeth for half an hour after exposure. Chewing sugar-free gum after eating is probably a great idea as it encourages the production of saliva.

See also this article on saliva and tooth dissolution from the Newcastle University Dental School and this article from the British Dental Journal.
Extrinsic sources of acid

There has been recent media publicity as well as scientific research to suggest that dietary practices and habits are changing. No longer do we have the 'three meals a day' routine but rather the habits of 'grazing' and 'snacking'. This is particularly the case with soft drink consumption: there has been an enormous increase in the total amount drunk and a considerable change in the age distribution of drinkers. At one time most soft drinks were confined to children but there is now good evidence to show that this is being carried forward to adult life, rather than 'graduating' onto tea and coffee drinking. Erosion may be particularly harmful to infants if drinks are taken from a feeder bottle used as a comforter. There have been significant associations shown between soft drink consumption and dental erosion, particularly the bed-time consumption of fruit-based drinks.

There are other sources of dietary acid besides soft drinks: teenagers and adults should be aware that many alcoholic beverages such as wine and particularly sparkling wine, are erosive. However, it is not just the pH that is important but rather the titratable acidity. Table 4 gives the pH and titratable acidity of some commonly consumed drinks both in children and adults, with an indication of their erosive potential. (The titratable acidity is the amount of alkali needed to be added to an acid to bring it up to a neutral pH. It therefore represents the amount of available acid and is an indication of strength and thus of erosive potential.) There are also acidic foods that may be implicated in the development of erosion eg fruit, pickles. yoghourt and sauces.
posted by maudlin at 2:03 PM on December 20, 2010


But maudlin, this isn't about dental hygiene!

In other words, I am not sure what the question is getting at. Presumably that acidic foods, specifically colas, should be more neutral. But for what reason, I do not know if it has nothing to do with dental health. Digestive health? The environment, in some way? Even acid erosion, which I thank you for addressing in a much better way than my waving of arms, is more of a concern with a balance of diet, or for certain individuals, than it is with one specific beverage.
posted by mikeh at 3:05 PM on December 20, 2010


Yeah, he made that disclaimer at the end, but he also said "Acid is bad for teeth though". So I guess we're both confused.

episodic, can you clarify what you're looking for?
posted by maudlin at 3:33 PM on December 20, 2010


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