Chocolate – How long can melted chocolate last

My wife is obsessed with Milka, and last time we were in Germany, she threw out all my clothes in order to fill an entire suitcase with it. When we got it home, it got piled in the freezer (not the freezer-in-the-garage-which-is-seldom-opened, but the regular one where we keep ice cream and frosty beer mugs). Took us more than 4 years to finish it. The last bit was effectively identical to the first. No noticeable change in the product.

Given that quality chocolate has no water (which is the primary freezer-spoilage agent), I'd say it would keep effectively indefinitely. If you're talking about candy bars which contain other ingredients, it may vary.

Generally though, things don't go "bad" in the freezer. They can get brutally freezer burned and disgusting, but there is no safety issue, as long as the food remains frozen. I once made a pie out of a quart of blackberries I found buried in the ice in an old-style freezer chest. Estimated age was on the order of twenty years, but they'd been preserved by the encroaching frost. Pie was delicious.

First off, pretty much everything stored in a properly cold freezer (0°F/-18°C) will be safe to eat forever.

The flavor will eventually go, e.g., by getting freezer burn and also by enzymatic degradation (if not blanched). How long this will take depends on exactly how you've stored them. In general, airtight packaging with no air inside seems to be best. For example, vacuum-sealed thick bags work well. Cheap, thin plastic "storage" bags don't work well. You can get around 8 months according to UNL. Colorodo State believes you can get 12 to 18 months.

edit: It also occurs to me that it matters what freezer you're using. The one on my fridge, for example, has fairly large temperature swings (yet mostly stays below 0°F) and automatic defrost, it freezer burns things much quicker than my chest freezer (which has a temperature variance of maybe 2°F, staying in the -3° to -1°F range)