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Walnut Creek District

Canning FAQ's

Below are some questions and answers relating to home canning.tomato juice jars

Water Bath Canning

What kind of canner is used for acidic foods?
Use a water bath canner.

How much water should cover the top of the jars?
Water should cover the jars at least one to two inches.

Can Iuse 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.

Why use water bath canning instead of pressure canning for acidic foods?
The common spoilage organisms in acid foods are yeasts and molds. They are easily destroyed at 212oF, the temperature of a boiling water bath.

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.

What types of foods are safe to can using the water bath method?
Fruits, tomatoes, pickled products, jams and jellies.

What parameter designates a food as acidic?
The pH should be 4.6 or below.

Can fruit be safely canned without adding sugar?
Yes. Sugar adds sweetness to the fruit.

How does sugar affect the texture of canned fruit?
Sugar makes the fruit firmer. It also protects the color, texture and flavor.

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.

When should you start counting the processing time when using the water bath method?
When the water comes to a rolling boil. It must be 212oF.

Why is the "open kettle" method of canning unsafe?
This method does not guarantee the destruction of organisms present in food. There is a high risk of spoilage organisms being transferred from the kettle to the jar. If the jars are then sealed without processing, spoilage organisms can grow.

Canning Tomatoes

tomatoe juice 2Which tomatoes are not suitable for canning?
Overripe tomatoes; tomatoes with soft spots or decayed areas; tomatoes picked from dead vines.

Can I use tomatoes picked from a frost-killed vine?
The freezing of the vine may lead to lower acidity in the tomatoes.

Do different tomato varieties affect the canning procedure or process?
No, the addition of acid to the process is adequate to cover all varieties.

Should 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.

What must be added to home-canned tomatoes to make them safe for water bath canning?
Add citric acid or lemon juice.

Is it safe to drink home-canned tomato juice that has a few little patches of mold on the surface?
No. Improper processing or undersirable tomatoes were used. Throw it out!

Is it safe to drink home-canned tomato juice that has separated?
Yes. Home canned tomato juice is made by the "cold break" method. The tomatoes are crushed before they are heated. The enzymes then start to break down the pectin that holds the tomato cells together. Commercially, tomato juice is made with the "hot break" method. The tomatoes are crushed and heated much quicker which destroys the enzymes before they have a chance to act. Therefore, this process produces a thick-bodied, homogeneous juice. Home canners cannot duplicate the "hot bread" method at home.

What are the hard, white deposits in my canned tomatoes?
These white deposits are calcium nitrate. It is safe to eat. The calcium nitrate precipitates out of the tomato as a result of mashing or pureeing. The deposits vary with the growing season and geographic region. It is usually found on the surface of the tomato product or attached to the lid or side of the jar. Simply remove with a clean spoon. If it is throughout the jar of product, it is safe to eat but the texture may be undersirable. It is hard and will not disintegrate when rolled between the fingers.

Pressure Canning

canning 10What parts of a pressure canner should be checked on a regular basis?
Every year, you should check the dial gauge, gasket, overpressure plug, and petcock. Before every use, the rack, weights, vents and gasket should be checked. Make sure the vents are clear and the gasket is in place.

If a dial reads 10 pounds per square inch when the master gauge reads 8 PSIG is it safe to be used?
No. Your canner will improperly process the food.

How do you vent a pressure canner?
Let steam escape through the "vent" (pressure regulator or weighted gauge opening)for 10 minutes.

Can mayonnaise jars be used for pressure canning?
No. Mayonnaise jars are not resistant to temperature extremes, so they break easily. The sealing edge of mayonnaise jars may be rounded rather than flat so lids may not seal. These jars can be used for canning acid foods in a boiling water bath.

I canned beans a week ago using a boiling water bath. It is a week later and I learned I should have used a pressure canner. Can I reprocess the beans in a pressure canner now?
NO! SInce more than 24 hours have passed since the beans were processed in the water bath, there is a good chance spoilage is already occurring. Throw them out!

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

Why is Clostridium botulinum used to determine safe processing procedures?
It grows in low-acid foods, in an air-free environment, may produce toxins before any signs of spoilage are present, and the toxin inactivates nerve cells and may because long-term paralysis, even death.

Why types of foods require pressure canning?
Vegetables, tomato-vegetable mixtures, meats, fish, and poultry. Pressure canning at 10 pounds per square inch will increase the temperature to 240oF. Along with a specific processing time, the bacteria spores that cause botulism will be destroyed.

What determines a food to be low-acid?
The pH of the food is 4.6 and higher.

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 in such a thick product is poor. Cubed pumpkin may be safely canned.

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 pressure canning processing.