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OSU Extension

College of Food, Agricultural, and Environmental Sciences

October 3, 2016 - 9:16am -- Anonymous

It’s the end of summer and the end of the canning season.  I’ve been out and about testing pressure canners and have seen more than 85 canners and talked with many of you about questions or problems that you might be having.  Below is a quick list of the most common questions I’ve received.  I hope that you will find the information helpful as you finish up your home food preservation.

*How tightly should the ringbands be put on when closing jars with two-piece lids?

Fingertip tight or if you want to be more precise, one inch past the point of first resistance.  Putting the ring on too tightly may cause the lids to buckle.

*Can food be reprocessed if it was incorrectly processed or if the lids failed to seal. 

If it’s within 24 hours, you may: refrigerate the food and use within two days, freeze the food (allow headspace in the jar for expansion of the food and drain the vegetables) or reprocess the food using the same processing time.

*What makes canned foods change color?

Oxidation may cause foods to darken at the tops of jars.  Oxidation is from air in the jars or too little heating or processing to destroy enzymes.  Overprocessing may discolor foods throughout the containers.  Pink and blue colors sometimes seen in canned pears, apples and peaches are caused by chemical changes in the coloring matter of the fruit.  Iron and copper from cooking utensils may cause brown, black and gray colors in some foods.  When canned corn turns brown, the discoloring may be because of the variety of the corn, the state of ripeness, overprocessing or copper or iron pans.  Packing liquid may dissolve coloring materials from the foods. 

*Can I use my pressure cooker or saucepan for home canning low-acid foods?  No, they are not recommended for canning.  The canner must be large enough to hold 4 quart jars by the new standards.

*Why is liquid lost from glass jars during processing?  The most common reasons for loss of liquid are packing jars too full, packing food too tightly into jars, changing pressure in a pressure canner or lowering pressure too suddenly.  If all air bubbles are not removed from jars before processing, the liquid may be lower in the jars after processing.

*Why does fruit float in the jars?  It may float because the pack is too loose or syrup too heavy or because some air remains in the fruit after heating or processing.

If you have home canning or freezing questions that you want answers to, give me a call at 330-264-8722.  Happy Harvest!