Head-space on canned jam

Garland · 07-31-2010, 09:13 AM

I've been making some jam for Christmas presents and also plan on entering some in our local Fair next month. One of the requirements for Fair entries is that the head-space on the jam be exactly 1/4" so I've been measuring that before water-bathing. BUT, on many of them the head-space changes after processing to be less so I can't enter those. I don't know what I can do to make it stay at 1/4"

Anybody with experience with this? Suggestions?

RiverRock · 07-31-2010, 09:25 AM

1/4" doesn't sound like much space...on most jars it would be in the threads which sounds high. All I can think of is to make sure your jam is cooked down (thinking long boil method as oppossed to using certo or pectin) and that using a wide-mouth jar would give you more flexability than a standard jar would. I hope you win!

Ajani · 07-31-2010, 11:09 AM

1/4" is standard for most jam recipes I've done. Once you fill the jar, use a narrow scraper or spatula (or even a butter knife) and run it around the sides to release any air bubbles. Then add more jam to readjust the headspace. Some fruits (or fruits which are slightly past their prime) hold more air, too. So be sure to follow the cooking instructions exactly to get the most air out of the cell walls as possible.

07-31-2010, 09:13 AM	#1
Garland Rose Trellis Join Date: Jun 2007 Posts: 3,308	Head-space on canned jam I've been making some jam for Christmas presents and also plan on entering some in our local Fair next month. One of the requirements for Fair entries is that the head-space on the jam be exactly 1/4" so I've been measuring that before water-bathing. BUT, on many of them the head-space changes after processing to be less so I can't enter those. I don't know what I can do to make it stay at 1/4" Anybody with experience with this? Suggestions? __________________ ~ Garland ~ INFJ ~ Mom to a big bunch of kids!

07-31-2010, 09:25 AM	#2
RiverRock Moderator Leaning, leaning, leaning on the everlasting arms. Join Date: Oct 2007 Location: In green pastures Posts: 9,767	Re: Head-space on canned jam 1/4" doesn't sound like much space...on most jars it would be in the threads which sounds high. All I can think of is to make sure your jam is cooked down (thinking long boil method as oppossed to using certo or pectin) and that using a wide-mouth jar would give you more flexability than a standard jar would. I hope you win! __________________ RiverRock, mom to a 24 year old diamond, 22 year old granite, 19 year old pearl, and 16 year old tiger eye. Married for 25 years to a rugged boulder and resting together on the one true Rock.

07-31-2010, 11:09 AM	#3
Ajani Rose Trellis Learning what I'm called to believe Join Date: Nov 2006 Location: Southern Ontario Posts: 3,153	Re: Head-space on canned jam 1/4" is standard for most jam recipes I've done. Once you fill the jar, use a narrow scraper or spatula (or even a butter knife) and run it around the sides to release any air bubbles. Then add more jam to readjust the headspace. Some fruits (or fruits which are slightly past their prime) hold more air, too. So be sure to follow the cooking instructions exactly to get the most air out of the cell walls as possible. __________________ ISFP (Fi Se)- The Artist Married to my high school sweetheart (possible ISTJ) The Boy - 04 (ETJ) Little Miss - 07(IFP) *My Edible Journey* Come share food with me. ~ Courage doesn't always roar. Sometimes courage is the quiet voice at the end of the day saying, "I will try again tomorrow." ~

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