Why does my diet soda taste off? Aspartame hydrolysis
Awesome! As someone who used to drink a <i>lot</i> of Diet Dr. Pepper (DDP) I could easily tell how close a given can (or bottle) was to its &quot;use by&quot; date. This makes for a great party trick [1] but otherwise has limited utility.<p>It also made for some socially awkward situations where, when visiting friends, they would want to have drinks on hand that their guests like and would go out of their way to get some DDP for me, not checking the date, and then serve out of date soda which tasted horrible.<p>Not surprising the rate of hydrolysis is temperature dependent so if you keep things refrigerated they last longer, but if you leave them out on the back porch in the summer where they get warm they go &#x27;non-sweet&#x27; relatively quickly.<p>I switched to water (or tea if I want caffeine) with diet sweetener in packets (which doesn&#x27;t go bad because no pesky water to &#x27;unzip&#x27; it). I wrote to the Dr. Pepper company once and suggested they design their beverage so that the sweetener was dry and only released when you opened it (I got the idea from the way the Guinness folks started selling Guinness in cans with a gizmo to put a head on it when opened. Alas, nobody at the company was interested in &quot;fixing&quot; a non-problem, they responded (nicely) that I should just be sure to check the date and included a coupon for a free six pack. Of course at that time (and is still true around Reno) the bottler doesn&#x27;t use an easily readable date code so it isn&#x27;t much of a solution.<p>[1] And by &quot;great&quot; I mean the nerds all are fascinated by it and the non-nerds were nominally repulsed that someone could have such familiarity with the hydrolysis profile as to call it out by taste.