Discolored preserves and jams

Quote:

Originally Posted by ferryman 

I recently discovered a stash of home-made preserves and jams that seem to have discolored over time. Does this discoloration affect the quality of the food? What causes it? The jars were stored in a cupboard adjacent to a refrigerator; could this affect the quality?

Somehow, in the canning process, you may have inadvertently got a micro-organism into the jam. It happens. I have the same problem when canning peaches and pears in the fall.  When doubt........throw them out!

If there were microorganisms, wouldn't the tops no longer be inverted?  if they pop when you open i'd think they'd be fine.  I think the problem is light and/or heat.  I've eaten jam i made that got a little darker and it was fine, as i am alive to attest

Siduri -- No!  You must have missed that day in school.  Not all toxic micro-organisms produce gas and invert a sealed dome.  Discoloration can mean many things.  It's true that not all of them are bad, but a few are potentially catastrophic.  Why take the risk?

Chefross is absolutely right! 

When in doubt, throw it out. 

BDL

Quote:

Originally Posted by boar_d_laze 

Siduri -- No!  You must have missed that day in school.  Not all toxic micro-organisms produce gas and invert a sealed dome.  Discoloration can mean many things.  It's true that not all of them are bad, but a few are potentially catastrophic.  Why take the risk?

 

Chefross is absolutely right! 

 

When in doubt, throw it out. 

 

BDL

I guess i wasn't in doubt.  .  And I missed the whole course, not just the day.  My reasoning was that between the acid of the fruit and the sugar it was pretty safe.  Not?
 

Quote:

Originally Posted by Anime Shefu 


"I guess i wasn't in doubt:) .  .  And I missed the whole course, not just the day.  My reasoning was that between the acid of the fruit and the sugar it was pretty safe.  Not?"
NO! that alone is not acidic enough to be sterile fruit expires right? So why shouldn't cooked fruit with some sugar it will still expire. DO NOT EAT...yes when in doubt...throw it out ASAP

You may be right, but the fact that fruit expires is irrelevant here - of course fruit expires, but that's why when there is a lot of it, it's preserved in jam - it's not cooked with "some" sugar, it's cooked with it's own weight in sugar.  That's one lot of sugar.  And jam is made with underripe fruit, which has more acidity than ripe fruit. 

There may be other reasons why it might be dangerous, but not that fruit expires.  By that reasoning,  jam should be thrown out in a week, when the fruit it's made from expires. 

Also, when fruit expires it ferments, and produces alcohol.  It still doesn't give you life-threatening diseases.  Or does it?

If the seal is unbroken and it's just discolored, my guess is that it's something to do with the light affecting the color through the glass. 

I'd be interested in one of our science experts to give an explanation.  I know there are guidelines for jam, but they take into account the extremes (when people haven't sterilized properly, when the seal is broken, when it may not have been made correctly) - the guidelines are always more cautious.  But is jam made with half fruit half sugar, cooked completely (without added pectin, so cooked really completely in order to jell) and poured into sterile jars that have been boiled for more than ten minutes (along with the ladle that is used to put it in the jars and the tongs used to pull them out) and they're left in the hot water till ready to fill with boiling jam, then sealed, is that jam dangerous? or will it just, at worst, taste bad?   I have some three-year old jam stored and don't want to throw it out if i don;t have to.  Been eating it like that for years.