How do food jar factories put negative pressure into the jar to begin with?
In: 87
Many food producers use nitrogen, rather than CO2 especially in bags of chips, cookies, and crackers.
This keeps products from oxidizing and contributes to the pressurization of the container.
We make a cooked barbecue sauce at my plant. We bottle it into glass at 200 degrees. Then it gets capped. It immediately goes into a very large cooling tunnel where it basically gets rained on for about an hour until it comes out the other side. Starts with hot water and the water is cooler and cooler until the end when it comes out around 80. The vacuum seal, if the seal was good, will be sucked down by the end. That little poppy thing on top of some bottles. If it isn’t down, we have a machine that detects it and kicks it off of the line.
Either heat the contents and put a cap on it when it’s really hot or have a machine poke a hold in the lid, suck out as much air as possible and then seal it to backup.
Either heat the contents and put a cap on it when it’s really hot or have a machine poke a hold in the lid, suck out as much air as possible and then seal it to backup.
We make a cooked barbecue sauce at my plant. We bottle it into glass at 200 degrees. Then it gets capped. It immediately goes into a very large cooling tunnel where it basically gets rained on for about an hour until it comes out the other side. Starts with hot water and the water is cooler and cooler until the end when it comes out around 80. The vacuum seal, if the seal was good, will be sucked down by the end. That little poppy thing on top of some bottles. If it isn’t down, we have a machine that detects it and kicks it off of the line.
We make a cooked barbecue sauce at my plant. We bottle it into glass at 200 degrees. Then it gets capped. It immediately goes into a very large cooling tunnel where it basically gets rained on for about an hour until it comes out the other side. Starts with hot water and the water is cooler and cooler until the end when it comes out around 80. The vacuum seal, if the seal was good, will be sucked down by the end. That little poppy thing on top of some bottles. If it isn’t down, we have a machine that detects it and kicks it off of the line.
Either heat the contents and put a cap on it when it’s really hot or have a machine poke a hold in the lid, suck out as much air as possible and then seal it to backup.
Some good comments here about home canning, and how it relies on simple things like thermal expansion and contraction, and the fact that bacteria off-gasses and adds pressure when present. (Basically “germ farts” can break the seal and let product leak out, so a leaky bottle of aunt judy’s tomatoes should be trashed).
But home canners usually use a pressure cooker – water boiled under pressure can get “hotter than boiling”, about 250°f vs. 212°f – so even more safety comes into play, and the environment in the pressure cooker becomes sterile, as does everything in the bottles and the bottles and lids themselves. It’s a very old-school, simple and brilliant solution for a time when a big part of the populace grew some or much of their own food and needed a way to store it long-term; many of those people were probably functionally illiterate (or science-illiterate), so a simple set of steps was needed, that could be taught to your kids. (My mother was born in the 1920’s in an Appalachian shack with no plumbing – she grew cucumbers in our yard and I’ve still never had better pickles than she made every summer).
The metal rings around the top of canning jars aren’t there to seal the jar closed – they’re to *protect the seal* from being knocked loose or chipped free. You just tighten them finger-tight.
Some good comments here about home canning, and how it relies on simple things like thermal expansion and contraction, and the fact that bacteria off-gasses and adds pressure when present. (Basically “germ farts” can break the seal and let product leak out, so a leaky bottle of aunt judy’s tomatoes should be trashed).
But home canners usually use a pressure cooker – water boiled under pressure can get “hotter than boiling”, about 250°f vs. 212°f – so even more safety comes into play, and the environment in the pressure cooker becomes sterile, as does everything in the bottles and the bottles and lids themselves. It’s a very old-school, simple and brilliant solution for a time when a big part of the populace grew some or much of their own food and needed a way to store it long-term; many of those people were probably functionally illiterate (or science-illiterate), so a simple set of steps was needed, that could be taught to your kids. (My mother was born in the 1920’s in an Appalachian shack with no plumbing – she grew cucumbers in our yard and I’ve still never had better pickles than she made every summer).
The metal rings around the top of canning jars aren’t there to seal the jar closed – they’re to *protect the seal* from being knocked loose or chipped free. You just tighten them finger-tight.
Some good comments here about home canning, and how it relies on simple things like thermal expansion and contraction, and the fact that bacteria off-gasses and adds pressure when present. (Basically “germ farts” can break the seal and let product leak out, so a leaky bottle of aunt judy’s tomatoes should be trashed).
But home canners usually use a pressure cooker – water boiled under pressure can get “hotter than boiling”, about 250°f vs. 212°f – so even more safety comes into play, and the environment in the pressure cooker becomes sterile, as does everything in the bottles and the bottles and lids themselves. It’s a very old-school, simple and brilliant solution for a time when a big part of the populace grew some or much of their own food and needed a way to store it long-term; many of those people were probably functionally illiterate (or science-illiterate), so a simple set of steps was needed, that could be taught to your kids. (My mother was born in the 1920’s in an Appalachian shack with no plumbing – she grew cucumbers in our yard and I’ve still never had better pickles than she made every summer).
The metal rings around the top of canning jars aren’t there to seal the jar closed – they’re to *protect the seal* from being knocked loose or chipped free. You just tighten them finger-tight.
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