Why do frozen vegetables go bad more quickly after thawing than fresh cut ones?
I left a pack of frozen vegetables (brocolli, carrot, cauliflower, green beans) in the fridge so it thawed. It went sour and slimy after a few days, (maybe 5) -- why?
If I cut the same fresh vegetables and store it in a plastic bag or container, it will be fine in a week or more.
What's the science behind that? Why do bacteria grow more quickly in frozen veggies being thawed than in fresh cut ones?
Best Answer
Very simply; freezing breaks the cell walls.
As ice takes up more space than water, as the vegetables freeze all the cells rupture.
Once defrosted, each cell is then little more than a slowly-leaking bag of nutrient, exposed to the open air. Whether or not any bacteria gets in & starts to breed is almost irrelevant by this time, as your 'leaky bag' is going to dissolve into a pool of its own juices pretty quickly.
This is why frozen veg is cook-from-frozen not cook-from-thawed. An hour might be OK, a day is starting to get a bit much. By 5 days, I wouldn't do anything other than move it to the recycle using tongs.
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Quick Answer about "Why do frozen vegetables go bad more quickly after thawing than fresh cut ones?"
Very simply; freezing breaks the cell walls. As ice takes up more space than water, as the vegetables freeze all the cells rupture. Once defrosted, each cell is then little more than a slowly-leaking bag of nutrient, exposed to the open air.How long are frozen vegetables good after thawing?
When is it safe to refreeze food? You can safely refreeze frozen food that has thawed\u2014raw or cooked, although there may be a loss of quality due to the moisture lost through thawing. To safely refreeze, the thawed product must have been kept cold at 40 degrees or below for no more than 3-4 days.How do frozen vegetables go bad?
Ice crystals begin to form on frozen vegetables as their time in the freezer is extended. If the ice crystals are removed and the vegetables retain their color and texture, they can still be used. Some common traits of bad frozen vegetables are loss of color, a shriveled size and caked on ice crystals.Are frozen vegetables OK if thawed?
Frozen vegetables shouldn't be defrosted because they can lose their crunchy texture. Additionally, defrosting frozen vegetables can cause them to lose the flavor and nutrients that are sealed in from their freezing process, especially if you defrost them a day or two prior to cooking.How long do frozen vegetables last in freezer once opened?
Vegetables can be frozen for up to 8-12 months. Keep them at a constant temperature and do not continuously refreeze them. With proper storage, they can often last beyond the date.Fresh or frozen food? Using SCIENCE to prove which is best with surprising results! - BBC
More answers regarding why do frozen vegetables go bad more quickly after thawing than fresh cut ones?
Answer 2
In additions to Tetsujin's answer, know that freezing, at least of home temps, does not completely stop degrading of the vegetable. One of the main reason most vegetables are blanched before freezing is to stop, or at least slow down enzyme actions that decay and degrade the color, texture and flavor. This helps some, but of course also can contribute to cell breakage and add some water which compounds this, so even this attempt to help stall degrading may aid in faster decay after thawing. That is, the item may be better quality when first thawed that it would have been without the blanching, but the post thaw breakdown might be even faster.
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