Jars leaking inside pressure cooker

When pressure cooking my jars of starter wort, I'm having trouble with the jars leaking part of their contents into the water meant for steam generation. The problem ends up being that the jars become covered in a cooked-on wort solution, and the inside the cooker needs to be cleaned more-so than normal after a run. The jars are fully sealed, and the lids placed on properly before starting. Has anyone else experienced this? Any tips?

 

I've never pressure cooked wort before, but my family canned a lot of food when I was growing up... I seem to remember my mom would only fill up the jars so far because of what you are talking about, maybe try adding a little less wort to the jars and see if that helps?

 

The pressure cooker should be allowed to cool slowly after the heat is turned off. Relieving the pressure before the cooker has cooled sufficiently can cause the wort in the jars to boil over spilling some of the contents. Do not remove the weighted rocker prematurely or otherwise suddenly reduce the pressure including spraying or pouring water over the cooker. This and allowing enough head room in the jars is important. Read the instruction manual carefully if you have one and follow the directions in every detail. You can download manuals for most of the commonly available pressure canners/cookers.

 

I'm leaving only negligible headspace (fraction of an inch), so that's probably the issue. I'm using the recommended amount of water (~1cup) and using the standoff rack, so I was thinking that only the water being directly heated on the bottom of the pot would be raised above it's boiling point and making steam to maintain pressure. Ideally the jars should be heating only via the steam condensing on the jars, and the pressure should be high enough that the contents are not at boiling temperature at that pressure, right?

If that's bass-ackwards, how much headspace should I be leaving?

EDIT: I'm using one of the older, "rocker-weight style" pressure cookers, so maybe the oscillation in pressure causes the jar contents to flash boil a bit every time the weight relieves the excess. However, the weight should only be removing the *excess* pressure, and not really allowing it to dip assuming the heat input stays constant. Dunno.

 

The temperature of the pressurized steam inside the cooker is something like 250*F IIRC and so will be the contents of the jars after 15 minutes at 15 psi. You are correct. The weight is a pressure regulator and it works very well if you follow proper procedure. Some of the weights are adjustable and permit a choice of pressures, ie 5, 10 & 15psi. The rocker relieves excess pressure in the process. I'm not sure if the contents of the jars would be boiling after 15 min @ 15 psi, but they will be at or near 250*. They could very well be boiling gently. The headspace in a jar allows for expansion of the wort as it is heated and helps minimize spillage if it boils some. The jars will go volcanic and boil over if the pressure is released very rapidly because the wort may be above the 212* boiling point at atmospheric pressure. I don't know the recommended head space, but the owner's manual should spell it out. The manual probably has some valuable safety tips too. Never a bad idea to go over those.

 

Yoop - Do you have experience with this? Any suggestions for proper headspace in the jars?

Catt - You're exactly right; the contents reach approx. 250F at 15PSI. Ideally, even though the contents of the jars is above normal boiling temperature, the pressure keeps the liquid from physically boiling. I'm following all the safety instructions and letting the cooker cool normally. Thanks for the reminder though, it's always good to review the instructions when dealing with steam under pressure.

 

The manual for my 16 qt Presto canner suggests a headspace of 1/2" to 1" depending on what it is you are canning. Some things like meat will expand some as it is heated and requires the additional head space. Wort should be OK with the 1/2" free-board.

 

Keep in mind that your wort is going to expand by something like 5% or so when you heat it up that much. I don't know how big your jars are, but I would leave more than a fraction of an inch even in a small one.

 

Better yet, follow the manufacturers directions. IIRC, some fractions of an inch are more than others.

 

The only time I've had this happen is when the seal on my canner wasn't set right and there was a sudden release of pressure. I went from almost full jars to half empty.

 

lol..it was nothing that dramatic. I probably lost around 3/4" from each 1qt jar.

 

I'd guess not enough headspace or too quick of a cool down then