# Storing arequipe in the can it was made. **URL:** \ **Category:** Factual Questions\ **Created:** [September 22, 2009, 8:56am UTC](https://boards.straightdope.com/t/storing-arequipe-in-the-can-it-was-made/511061 "2009-09-22T08:56:55Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![Sapo](https://avatars.discourse-cdn.com/v4/letter/s/ec9cab/32.png) [@Sapo](https://boards.straightdope.com/u/Sapo)\ **Post date:** [September 22, 2009, 8:56am UTC](https://boards.straightdope.com/t/storing-arequipe-in-the-can-it-was-made/511061/1 "2009-09-22T08:56:55Z")
If I make arequipe by boiling a can of sweet condensed milk, is it safe to just leave it in the can?. Will it hold for as long as the original sweet condensed milk would (which is forever if the can doesn’t rust)? The can hasn’t been opened and boiling shouldn’t damage the can at all, right? Boiling something for 3-4 hours is a big use of energy and I would love to do 6 cans of the stuff at a time and be done for the year. > [@](#): > > For the uninitiated, arequipe is a sweet common in South America. Its preparation is long and tedious if you do it the grandma way, but a close enough substitute is made by simply boiling a can of sweet condensed milk fully covered in water for 3-4 hours inside the unopened can. The sugar caramelizes and it all turns a rich dark brown. > > You can spread the stuff on whatever you want (great for cake filling too). Best use of it is spreading it on a very thin pancake (half the flour on the recipe), rolling it, and bathing the stuff in flambeed dark rum. Good stuff. ---
**Author:** ![GilaB](https://avatars.discourse-cdn.com/v4/letter/g/8e7dd6/32.png) [@GilaB](https://boards.straightdope.com/u/GilaB)\ **Post date:** [September 22, 2009, 3:00pm UTC](https://boards.straightdope.com/t/storing-arequipe-in-the-can-it-was-made/511061/2 "2009-09-22T15:00:53Z")
I have no idea, but even if it doesn’t keep, couldn’t you keep the boiled cans in the freezer? If nobody knows, you could boil six cans, freeze five, and keep one on the shelf for a while. After a suitably long time (a month? two?), open it and check it out. If it’s not spoiled, you can take the other five out of the freezer, but if it is, the others should still be good. ---
**Author:** ![Grither](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/grither/32/425_2.png) [@Grither](https://boards.straightdope.com/u/Grither)\ **Post date:** [September 22, 2009, 6:30pm UTC](https://boards.straightdope.com/t/storing-arequipe-in-the-can-it-was-made/511061/3 "2009-09-22T18:30:11Z")
> [@Sapo](#): > > If I make arequipe by boiling a can of sweet condensed milk, is it safe to just leave it in the can?. Will it hold for as long as the original sweet condensed milk would (which is forever if the can doesn’t rust)? The can hasn’t been opened and boiling shouldn’t damage the can at all, right? > > Boiling something for 3-4 hours is a big use of energy and I would love to do 6 cans of the stuff at a time and be done for the year. I’ve heard of this method of making caramel before, and I still can’t figure out why the cans don’t explode. And the thought of the mess that would ensue from that horrifies me. ---
**Author:** ![AskNott](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/asknott/32/5790_2.png) [@AskNott](https://boards.straightdope.com/u/AskNott)\ **Post date:** [September 22, 2009, 6:44pm UTC](https://boards.straightdope.com/t/storing-arequipe-in-the-can-it-was-made/511061/4 "2009-09-22T18:44:56Z")
> [@Grither](#): > > I’ve heard of this method of making caramel before, and I still can’t figure out why the cans don’t explode. And the thought of the mess that would ensue from that horrifies me. I can’t say exactly why they don’t explode, but anything in a bath of boiling water will never get hotter than the boiling point of water. Depending on your altitude, it’s close to 212° F. I’d be more worried about freezing it. The water molecules in the milk will expand when they crystalize. ---
**Author:** ![Sapo](https://avatars.discourse-cdn.com/v4/letter/s/ec9cab/32.png) [@Sapo](https://boards.straightdope.com/u/Sapo)\ **Post date:** [September 22, 2009, 7:41pm UTC](https://boards.straightdope.com/t/storing-arequipe-in-the-can-it-was-made/511061/5 "2009-09-22T19:41:20Z")
Right, you are cooking it in a _bain marie_ which means it won’t go over boiling temperature. No matter at what altitude, I am guessing that the boiling point of sweet condensed milk is higher than water, so no chance of explosion. To all who haven’t tried this, do. Amazing results for zero skill and effort. I also agree that freezing it might lead to all kinds of bad things happening. I have seen cans in the freezer before. Not of arequipe, but of enough other things to dissuade me from trying. Plus, space in my freezer is normally at a premium. The question then is, does boiling for 3-4 hours somehow damage the can and the way it seals and protects the food? It sounds like you are just giving it an extra layer of pasteurization, but. ---
**Author:** ![Shalmanese](https://avatars.discourse-cdn.com/v4/letter/s/45deac/32.png) [@Shalmanese](https://boards.straightdope.com/u/Shalmanese)\ **Post date:** [September 22, 2009, 9:11pm UTC](https://boards.straightdope.com/t/storing-arequipe-in-the-can-it-was-made/511061/6 "2009-09-22T21:11:36Z")
arequipe is a close cousin to dulce de leche. It’s fine to store either of those in their original cans at room temperature practically indefinitely. ---
**Author:** ![dracoi](https://avatars.discourse-cdn.com/v4/letter/d/90db22/32.png) [@dracoi](https://boards.straightdope.com/u/dracoi)\ **Post date:** [September 22, 2009, 9:12pm UTC](https://boards.straightdope.com/t/storing-arequipe-in-the-can-it-was-made/511061/7 "2009-09-22T21:12:25Z")
I’m sure that the can is safe from a microbial perspective. It’s already been pasteurized, and boiling it again for a few hours should kill anything that might have survived initially. What I couldn’t say is whether there’s some potentially harmful chemistry that might go on inside after the cooking. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [September 22, 2009, 10:20pm UTC](https://boards.straightdope.com/t/storing-arequipe-in-the-can-it-was-made/511061/8 "2009-09-22T22:20:51Z")
> [@dracoi](#): > > What I couldn’t say is whether there’s some potentially harmful chemistry that might go on inside after the cooking. [caramelization chemistry](http://www.food-info.net/uk/colour/caramel.htm) > [@](#): > > difructose-anhydride > … > \* Caramelans (C24H36O18) > \* Caramelens (C36H50O25) > \* Caramelins (C125H188O80) > … > Besides diacetyl hundreds of other flavour compounds are produced for instance furans like hydroxymethylfurfural (HMF) and hydroxyacetylfuran (HAF), furanones such as hydroxydimethylfuranone (HDF), dihydroxydimethylfuranone (DDF) and maltol from disaccharides and hydroxymaltol from monosaccharides. I’m not seeing any acid formation, or generation of anything else that’d react with a metal can. Storage in the unopened can is _probably_ safe. ---
**Author:** ![Sapo](https://avatars.discourse-cdn.com/v4/letter/s/ec9cab/32.png) [@Sapo](https://boards.straightdope.com/u/Sapo)\ **Post date:** [September 22, 2009, 11:07pm UTC](https://boards.straightdope.com/t/storing-arequipe-in-the-can-it-was-made/511061/9 "2009-09-22T23:07:27Z")
If it helps, the cans of the brand I buy (Aguila) don’t seem to be lined with anything. Just the bare metal. ---
**Author:** ![thelurkinghorror](https://avatars.discourse-cdn.com/v4/letter/t/7c8e57/32.png) [@thelurkinghorror](https://boards.straightdope.com/u/thelurkinghorror)\ **Post date:** [September 22, 2009, 11:55pm UTC](https://boards.straightdope.com/t/storing-arequipe-in-the-can-it-was-made/511061/10 "2009-09-22T23:55:03Z")
It’s more commonly called dulce de leche in English/the US. I think arequipe is only common in Colombia and Venezuela? There is a danger of it exploding. If you’re boiling it, it needs to be completely underwater at all times, which means you need to top it off semi-frequently. It’s been awhile since I made some, but I started boiling it and then finished it off in the oven, where there is little risk of explosion. I have left **open** cans in the fridge for quite some time with no ill effect. ---
**Author:** ![Projammer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/projammer/32/559_2.png) [@Projammer](https://boards.straightdope.com/u/Projammer)\ **Post date:** [September 23, 2009, 1:30am UTC](https://boards.straightdope.com/t/storing-arequipe-in-the-can-it-was-made/511061/11 "2009-09-23T01:30:36Z")
This one is easy. Just try it. Seriously. Condensed milk is what? A buck? Buck and a half? Prep 6 cans and put 5 of them back in the pantry. Use the first one normally. Grab the next one when you’re ready. If it’s bad check another. If it winds up they’re all bad just toss em and make up another like you have been. Check back in a year and let us know how it went. eta: 3 cans make an excellent caramel pie. Just dump em in a crust ---
**Author:** ![Sapo](https://avatars.discourse-cdn.com/v4/letter/s/ec9cab/32.png) [@Sapo](https://boards.straightdope.com/u/Sapo)\ **Post date:** [September 26, 2009, 8:17pm UTC](https://boards.straightdope.com/t/storing-arequipe-in-the-can-it-was-made/511061/12 "2009-09-26T20:17:46Z")
> [@thelurkinghorror](#): > > It’s more commonly called dulce de leche in English/the US. I think arequipe is only common in Colombia and Venezuela? Sorry I missed this the first time around. Yes, Arequipe is what US ice cream makers have been calling Dulce de Leche. Dulce de Leche covers other types of milk-sugar confections, so you could say that Arequipe is a type of Dulce de Leche. Dulce de Leche goes all the way from liquid to hard fudge and from clean white to dark caramel brown. It is also shaped in all forms and colored and decorated. Arequipe is a goopy mess of medium to dark caramel color and won’t hold shape. Also yes, the word Arequipe comes from Colombia and Venezuela, from where they claim this originates.