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Headspace Importance
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Posted by gmreeves (My Page) on Mon, Jun 29, 09 at 15:59
| This weekend I had my first canning experience and all in all I think I did pretty good for one morning. I made a batch of Annie's Salsa, Bread and Butter Pickles, Strawberry Lemonade Concentrate, and Jardinaire. As an experiment, I went ahead and canned the leftovers in there own jar. So of each batch, I have anywhere from 1/3 of a jar to 3/4 of a jar. They all appeared to seal so I'm wondering if there is a problem with storing them and what that problem is. My intention was just to see if they would seal and then eat them right away anyway. I'm just curious as to what the importance of the headspace is and why it needs to be followed to the 1/4" increments. |
Follow-Up Postings:
RE: Headspace Importance
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| It is important for safety because the idea of processing is to not only destroy bacterias, but it also drives out the air in the jars. If you have too much air the food can darken, and also can spoil. Never fill just a partial jar and process it. |
RE: Headspace Importance
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| Only way it could possibly be safe would be to increase the processing time substantially. You'd have to compute the correlation between the excessive amount of air in the jar and the processing time needed to remove it - if that were possible to do. But it ain't. ;) So now you have jars that must be refrigerated and consumed ASAP because bacteria is free to grow in them. From the NCHFP FAQs on canning: Do I really need to leave a certain amount of headspace in the jar?
Yes, leaving the specified amount of headspace in a jar is important to assure a vacuum seal. If too little headspace is allowed the food may expand and bubble out when air is being forced out from under the lid during processing. The bubbling food may leave a deposit on the rim of the jar or the seal of the lid and prevent the jar from sealing properly. If too much headspace is allowed, the food at the top is likely to discolor. Also, the jar may not seal properly because there will not be enough processing time to drive all the air out of the jar. Dave |
RE: Headspace Importance
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| Gotcha. I was aware of the not filling too full so you didn't have bubbling contents affecting the seal but didn't think about all of the air escaping. I was assuming that if it sealed then it was good to go. THanks for clearing it up. I plan on eating the partially canned goods anyway and they are already in the fridge. I was just wondering about the details of it. |
RE: Headspace Importance
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| I've got another question regarding the headspace and not completely filling the jars. What if I run out of veggies to fully pack the jar but have enough brine to top off the jar to the correct headspace. Is it still safe to can and preserve or should I still refrigerate and eat ASAP? I would think that the only problem would be that the food would be overly processed but is that a safety concern? |
RE: Headspace Importance
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| Provided the jars are filled to the proper liquid level (headspace) you should have no concerns about how much of the product is in the jars packed in the liquid to the proper level. With less solids in the jar, they may tend to float more. Thats one reason I prefer using the regular mouth jars as opposed to the wide mouths, because the taper helps to keep the solids usually below the liquid. |
RE: Headspace Importance
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| Agree with Ken - as long as that extra space is filled with liquid rather than air there is no safety concern. But if the left-overs isn't much, just eat it right then as a reward for all the good work you have done. ;) Dave |
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