Q: Last year, I tried to can garden carrots. I followed the directions to the letter, but they turned white and soured. What did I do wrong?

A: It’s hard to say exactly what might have gone wrong with your carrots. Discoloration like you describe could be caused by minerals in the water, anti-caking ingredients in the salt (if it wasn’t pure canning salt) or other flavoring ingredients. But the most likely culprit is bacteria or other micro-organisms. Carefully discard any jar of spoiled food to prevent possible illness to you, your family or pets.

Spoilage can happen for many reasons. Your carrots were probably not processed long enough or at a sufficiently high temperature. A water-bath canner is fine for processing acidic foods, such as peaches, that don’t require a temperature higher than the regular boiling point of 212°F. Low-acid vegetables such as carrots, however, must be processed in a pressure canner, which allows them to reach a temperature of 240°F. or higher. The proper pressure level must be maintained throughout the entire processing period; if it falls below that level, you’ll need to reprocess for the full time.

Process timing should be increased at high altitudes. Be sure the pressure gauge on your canner is accurate. Also, jars and lids must be very clean; even though the processing method kills bacteria, many people like to sterilize the jars and lids before filling and processing them.

For helpful resources for preserving, visit the extension services website in North Dakota (www.ext.nodak.edu) and North Carolina (www.ces.ncsu.edu), the website of the National Center for Home Food Preservation at the University of Georgia (www.uga.edu/nchfp) or Jarden Home Brand’s website, the company that sells Ball and Kerr jars (www.homecanning.com).

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