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Archive for Wednesday, July 10, 2002

Different foods require different canning methods

July 10, 2002

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Is it safe to use the food in a jar that has come unsealed during storage?

No. Loss of seal is a sign of spoilage. Throw it out.

Should you throw away the food if you find brown or black deposits on the underside of the lid when it is opened?

No. These deposits are harmless. It is caused by tiny pinholes in the lid allowing the acid to react with the metal in the lid.

What types of foods require pressure canning?

All low-acid foods with a pH of 4.6 or higher must be pressure canned. They include vegetables, tomato-vegetable mixtures, meats, fish and poultry. Pressure canning at 10 pounds will increase the temperature to 240 degrees. Along with a specific processing time, the bacteria spores that cause botulism will be destroyed.

Tomatoes are a high-acid food. If you add celery, onion and green pepper to tomatoes, does this product require pressure canning?

Yes. You have added low-acid foods, which require the pressure canning processing.

I canned shredded carrots, but used a processing time for 1/2-inch chunks. What's wrong with that?

Shredded carrots will pack more carrot into the jar with less room for water to circulate. The water carries the heat into the food, and if it can't circulate, the heat will not penetrate as fast, so food in the center of the jar will not be processed adequately to kill all bacteria.

If you want to can mixed vegetables, how do you decide on the processing time?

Use the processing time for the vegetable with the longest processing time listed.

Why is it not recommended to can mashed pumpkin?

Heat penetration for such a thick product is poor. Cubed pumpkin may be safely canned.

Can vegetables be safely canned without salt?

Yes. Any vegetable may be canned without salt. The purpose of adding salt is for flavor only.

What kind of canner is used for acidic foods?

Use a water bath canner.

Why use water bath canning instead of pressure canning for acidic foods?

The common spoilage organism in acid foods are yeasts and molds. They are easily destroyed at 212 degrees, the temperature of a boiling water bath.

Can I can safely using the open kettle method?

No. It doesn't guarantee destruction of organisms in the food. Also, spoilage organisms can transfer from the kettle to the jar and get into the food. If the jars are then sealed without processing, the spoilage organisms can grow.

What types of foods are safe to can using the water bath method?

Acidic foods with a pH of 4.6 or below are safe to can using the water bath method. They include fruits, tomatoes and pickled products.

How much water should cover the top of the jars when using the water bath method of canning?

At least 1 to 2 inches of water should cover the jars.

Can I use a pressure canner as the pan for water bath canning?

Yes, as long as it is deep enough and it has a suitable rack for the jars to set on.

When do you start counting the processing time in a water bath canner?

When the water comes to a rolling boil.

What can I do if the water level gets to low?

Add boiling water to keep the boiling process going.

Can fruit be safely canned without adding sugar?

Yes. Sugar only adds sweetness to the fruit and makes the fruit firmer. It is not used as a preservative when canning.

What kind of thickener is used to make canned cherry pie filling?

Use modified corn starch, Clear Jel A. There are no substitutions.

What are the advantages of using a hot-pack method of canning?

The hot-pack method inactivates enzymes quicker to help retain more vitamins. In peaches, the hot-pack method prevents "floaters." Liquid won't be lost during processing. Also, in the case of peaches, they won't turn brown on top and more peaches will fit in the jar.

Which tomatoes are not suitable for canning?

Overripe tomatoes; tomatoes with soft spots or decayed areas; tomatoes picked from dead vines.

Do different tomato varieties affect the canning procedure or process?

No, the addition of acid, such as citric acid or lemon juice, to the process is adequate to cover all varieties.

Can you can yellow tomatoes the same as red tomatoes?

Yes. Yellow tomatoes are not low in acid even though they are described that way. They can be safely processed in a water bath canner.

Is it safe to drink home-canned tomato juice that has a few little patches of mold on the surface?

No. Improper processing or undesirable tomatoes were used. Throw it out.




 Susan Krumm is an Extension agent in family and consumer sciences with K-State Research and Extension-Douglas County, 2110 Harper St. She can be reached at 843-7058.

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