Why didn't my jello set?
I found a box of lime jello that I have had for a while (at least 6 months). I made it last night, following the directions (boiling water, etc), and left it in the fridge til today. I went to eat it just now, 24 hours later, and it is only set in parts - there is still lots of liquid, and it isn't as jelled as I would expect - it's chunky, not a solid wiggling mass of jello goodness.
Steps I took:
Boiled water (a bit more than a cup) in a pot on my stove. Measured one cup of the boiling water, poured it into a pyrex bowl, added the packet of lime jello powder. Mixed it until it was dissolved, then added one measured cup of cold water. Stirred it a bit, then put the lid on the bowl and put the bowl in my fridge. Didn't add any fruit or anything.
What could have gone wrong?
Could you possibly recount the exact steps you took, for example: how much boiling water did you use and how long did you stir it? Whaen did you add cold water and/or ice? I just never had that experience so knowing the details might help solve the mystery of the un-jiggly Jello. Also, did you add any fruit and if so, what and how much?
Are you sure about the "mixed it until it was dissolved" part? The sugar/sweetener goes in quickly, but the gelatin turns clear, hard to see, and takes a minute or two of stirring to really go in. A sign of this being the problem would be a region of extra-hard gelatin on the bottom of the bowl.
Covering jello while it sets is not usually a problem. At my last job the pantry person covered the jello every time it was made while setting. This was due to health code regulations. Having the jello for that long usually isn't an issue either unless there was some way moisture got to the box and may have compromised the gelatin or even caused mold growth. Was the box expired?
Its not so much that the Jello expires but that over time moisture even in low levels can cause ingredients to break down and cause mold spores and things to grow. The ingredients of Jello are very simiple mostly sugar, gelatin, food coloring and "natural flavors".
It's possible the lid may have caused condensation from any residual heat to fall back into the jello, resulting in too much liquid.
Every site I found on the internet said to cover it only after it's cooled down. Plastic wrap will do fine. Once it has gelled properly, you can put the lid back on to prevent it from picking up other smells or flavors from the fridge.
It sounds like you didn't use pure gelatine, but a pre-mixed product. The way you describe it - with sections which are set and sections still liquid - it sounds like a clumping problem to me. The very weird directions you mention increase my suspicion.
Normally, if you put dry gelatine in hot water, parts of it will change immediately, while parts will stay dry. This is why you bloom gelatine in cold water until it is thoroughly hydrated, and then gently melt it on low heat. Too much heat will inhibit setting. I suppose that the mix manufacturer created finer-ground gelatine powder than usual and mixed it with something else, probably dextrose, to ensure immediate dispersion and hydration without clumping, and it probably works well enough in most cases.
There are several things which can have gone wrong for you. Maybe your pyrex bowl didn't have enough thermal mass to cool the water enough before you added the package and the gelatine got slightly overheated. Maybe you had stored the package not dry enough, so the dextrose clumped during storage and now the gelatine wasn't dispersed, so it stayed in chunks after hitting the water. Maybe you didn't stir it well enough to mix it evenly. Or something else entirely - the directions don't seem like the best way to handle gelatine.
You can try to save the next package.
I would start with letting the water cool just a little bit before stirring in the jello, maybe 75 or 80°C.Then I would take a good look at the package content. If there are clumps in it, there is a good chance it won't work properly. I don't know what will help in this case, maybe putting it through a food processor. (Just sieving out the clumps is not good; you may be throwing away the gelatine and keeping the dextrose). Then I would try to give it a really good and thorough stir before adding the cold water, so everything is perfectly dissolved, and another thorough stir after the cold water, so it is the same temperature and concentration everywhere.
I can't promise that this will help (I may have made false assumptions here, never having used a package of premixed jello), but it seems the likeliest solution.
Update Kristina Lopez says that lower initial temperature won't work with jello. I proposed this because gelatine is succeptible to overheating, but didn't consider that maybe starting from lower temperature will prevent sufficient dissolving once the cold liquid is stirred in. I guess you could still try out different heating startegies, but if somebody can predict how they'll turn out, it's not me, obviously my experience with pure gelatine is not sufficient here. So I'm striking that part of the answer and leaving in the break-up-clumps suggestion, as this is a thing I am more certain of. (I have had this problem with mixes of other gelling agents, for example jam sugar).
She said it was lime flavored jello which means it was a premix. You always use boiling water for this type of mix. Your suggestions would result in a failure to dissolve the jello properly - I've made that mistake before! ;-)
You're right. I use the word jello generically and should instead, say gelatin dessert mix. Thanks!
@TFD, the OP did say lime jello so certain assumptions were made. I still agree that your callout was appropriate. :-)
I am aware of the meaning of "jello" even though I haven't handled the actual brand-name product, nor any of the premade gelatine mixes available here in Germany. @Kristina thank you for providing empirical disconfirmation for my theory; I don't know how exactly jello is modified as compared to pure gelatine, so there is always the chance of me being wrong when making such assumptions.
Too much water. I noticed that you used more than one cup of boiling water and one cup of cold water. At most, a 1:1 ratio is needed. I usually short the cold water by 1/4 of a cup, using one cup of boiling and 3/4 cup of cold, especially when using an old mix. For me, that ratio sets up every time.