With the pandemic still raging, our immediate family took a chance and gathered for Thanksgiving dinner. This is one of my favorite holidays, as work is unlikely to call, we gather with those closest to us, and there is a turkey dinner. I love turkey and all of the side dishes. Producing such a spread is impractical for a routine dinner, but is more feasible for a larger group. As a bonus, I try and angle for the turkey carcass, to make stock at a later date. In years past, I portioned the finished stock into ziplock bags and placed the bags in the freezer. This year, we tried something new - canning the stock.
We have been canning food for years, but we processed all of our jars using the water bath method. Those familiar with canning know that water baths are good for high-acid foods such as fruit jellies and pickles. Tomatoes can be canned in a water bath, but nearly all tomato-based recipes call for adding acid in the form of lemon juice or citric acid. Water bath canning raises the food temperature to 212 degrees, the boiling point of water, to kill yeast and mold and degrade enzymes. Higher temperatures are needed for killing bacteria. Bacteria do not grow in acidic foods, but are a problem in low-acid foods such as unpickled vegetables and stock. For such foods, you need to bring out the big gun: a pressure canner.
We had a coupon for 20 percent off a purchase from our local hardware store, and decided to use it on a 16-quart Presto pressure canner. Presto makes a larger version, but at the moment I cannot envision processing the amount of jars that a larger canner will hold. Processing a larger number of jars also requires double stacking, which I do not like doing.
As my turkey stock bubbled away, I washed and assembled the canner, and read the directions. Pressure canners are sealed vessels, working on the principle that the boiling point of a liquid rises with an increase in pressure. The ideal gas law in action. Pressure is created by water in the canner, which boils and forms steam. Because of the pressure, the water boils at a higher temperature, which kills bacteria and solves the problem associated with using a water bath canner for low-acid foods. Pressure, heat, and steam also create safety issues. Modern canners are equipped with pressure relief devices to reduce the potential for overpressurizing and rupturing (i.e., exploding), but there is still plenty of heat and steam.
Following the directions exactly created some problems. For example, you are supposed to heat 3 quarts of water and then pour the hot water into the canner before placing the hot, filled jars inside. You also have to heat the jars to reduce the potential for thermal shock, sterilize the lids, and boil the stock. That occupies five burners on a four-burner stove, with three of the pots being quite large. I instead heated the 3 quarts of water directly in the canner pot, eliminating one pot. I heated the jars in our water bath canner, and then pulled that pot off the stove as water retains heat for a long time. Once everything was heated, I pulled the stock off the stove, filled and sealed one quart jar at a time, and placed the jar in the canner. I ended up with four jars for a gallon of turkey stock.
On went the canner lid, and the burner was turned to full. I vented the canner for 10 minutes in accordance with the instructions, placed the relief valve weight on the vent, and adjusted the heat when 11 psi of pressure was reached. I had a little trouble adjusting the heat and pressure at first, as the directions simply stated to turn the heat down to reduce pressure. Water does not respond quickly to such changes, so I ended up reducing pressure by lifting the relief value weight to vent steam in short bursts while avoiding scalding. After about 10 minutes, I had the pressure and temperature dialed in, but stood nervously by the stove for the entire 25 minute processing time just to be sure.
After 25 minutes, I turned off the burner and moved the canner to a cool burner. Following the directions to depressurize the canner, I removed the lid and was rewarded with four unbroken and sealed quarts of stock. It is always nice when something works, I thought to myself as I heard the popping of sealing jar lids. These canners have always made me nervous as there is plenty to go wrong. The ring seal has a lifespan of about 3 years (supposedly), and the dial gauge is supposed to be calibrated annually. Time will tell if I feel more relaxed about pressure canning.
Store shelves are slowing starting to refill with canning supplies following the autumn rush. The pressure canner will give us another tool to preserve food. Given our garden plans for next year, we may need every jar we can find.
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