Food Safety Frequently Asked Questions

• Can vacuum packaging replace canning fruits and vegetables?
• Can steam canners be used in place of boiling water bath canners?
• What causes liquid loss in jars of home canned fruits and vegetables?
• Can thickened fruit pie fillings be canned at home?
• Is it all right to pickle “acid free” burpless cucumbers?
• What causes pickling liquid to look cloudy?
• Can a pressure canner be used on a solid element cook top or a smooth top range?
• Can low-acid foods (vegetables, meat, fish, and poultry) be reprocessed if it was incorrectly processed or if the lids failed to seal?
• My pressure canner is the self-venting type. Does that mean it still needs to be vented 10 minutes before closing the vent?
• Can a water bath canner be used on a ceramic cook top?
• When canning and the jar seals, am I assured the food will be safe to eat?
• What kind of liquids can I use over my fruit when canning?
• Can I preserve Asian Pears?
• There are white deposits around the tops of my jars of canned tomatoes. Are they safe to eat?
• What causes lids to buckle?
• My pressure canner is the self-venting type. Why do other instructions say to vent all pressure canners for 10 minutes?
• Can I use old pickle recipes?
• Why is it recommended to process pickles in a simmering or boiling water bath?
• Why should meat be pre-treated before drying into jerky?

Can vacuum packaging replace canning fruits and vegetables?

Vacuum packaging machines will extend the storage time of refrigerated food, dried foods, and frozen foods. However vacuum packing machines or sealers are NOT a substitute for heat processing of home canned foods.

Perishable foods packed in a vacuum package must be refrigerated or frozen. They cannot be safety stored at room temperature. The removal of most of the oxygen does not inhibit all growth of bacteria. Some bacteria that grow in a low-oxygen environment can cause food spoilage. These bacteria can cause serious illness or death in humans.

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Can steam canners be used in place of boiling water bath canners?

Research on steam canners has found that food canned in them is not heated to a temperature as high as when the same food is canned in a boiling water bath canner. The lower temperature results in less killing power of the bacteria, under processing and considered a risk of spoilage. Therefore the use of steam canners for home canning is NOT recommended.

In addition to unsafe canning temperatures steam canners can cause steam burns to those using them, and increased steam burns.

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What causes liquid loss in jars of home canned fruits and vegetables?

There are a number of reason why liquid could be lost from jars of home canned foods. The most common reasons include: packing the jar too full, food packed so tightly that liquid does not fill the spaces between the food, starchy foods absorb extra liquid, liquid covering raw food is not boiling, jars in boiling water bathe are not covered with 1–2 inches of water, pressure in pressure canner fluctuates during processing, removing jars too quickly from the boiling water bath canner. For a more complete list contact the WSU Extension office.

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Can thickened fruit pie fillings be canned at home?

Commercially canned pie filling are thickened with modified food starches that resist breakdown or thinning during the processing. WSU Extension does have some fruit pie fillings that are thickened with a modified food starch. For those recipes and where to find the Clear-jel thickening product contact the WSU Extension office.

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Is it all right to pickle “acid free” burpless cucumbers?

Yes, however, the best quality pickles are made from pickling cucumbers. There are not guarantees that the burpless cucumbers will produce good pickles.

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What causes pickling liquid to look cloudy?

Anti-caking ingredients in table salt make the liquid cloudy. That is why pickle recipes call for pure granulated salt.

In fermented pickles, yeast development during fermentation causes cloudiness Cloudy liquid may also be a sign of spoilage. Before using the pickles, examine them for other signs of spoilage (spurting liquid, mold, off-odor, mushiness, slipperiness).

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Can a pressure canner be used on a solid element cook top or a smooth top range?

For a pressure canner to work successfully on a smooth top range, the canner bottom must be flat and in contact with the cook top. Most heavy cast aluminum canners meet these specifications. Lighter weight stamped aluminum canners have a concave bottom. If the concavity is greater than 1/8 inch, the canner will not perform effectively. To measure the concavity, place a straight edge across the canner bottom and measure the distance to the canner bottom with a ruler.

Solid element cook tops require heavy gauge, flat, smooth bottom utensils that have no more than one inch overhang beyond the element. Most pressure canners are too large to be used on solid element cook tops.

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Can low-acid foods (vegetables, meat, fish, and poultry) be reprocessed if it was incorrectly processed or if the lids failed to seal?

If less than 24 hours have gone by since the food was processed, do one of the following:

1. Refrigerate the food and use it in the next day or two.
2. Freeze the food. Drain vegetables before freezing.
3. Reprocess the food. Use the same jars or put in clean hot jars. Use new lids. Process again for the full time. The quality of the twice-processed food will be poor.

If it has been more than 24 hours, the food must be thrown away.

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My pressure canner is the self-venting type. Does that mean it still needs to be vented 10 minutes before closing the vent?

All pressure canners, including ‘self-venting’ pressure canners, do need to be vented 10 minutes before the pressure is allowed to rise. This venting time is a way to be certain that all air is removed from the pressure canner.

Research has shown that under some conditions (particularly with the raw-packed foods) all air may not be removed from self-venting pressure canners. If there is air in the pressure canner, the temperature is much lower than if the canner contains only water and steam.

Can a water bath canner be used on a ceramic cook top?

For a water bath canner to work successfully on a ceramic cook top, the canner bottom must be flat, in contact with the cook top and extend no ore than 2 inches beyond the design on the cook top surface.

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When canning and the jar seals, am I assured the food will be safe to eat?

No. It takes a lot less heat to seal the lid than to properly process the contents of the jar. If you followed the directions correctly, you can be sure the food will keep and be safe to eat. The entire heat processing time is developed in order to get all the air out of the jar and air out of the food. The air present is what will cause spoilage such as mold growth, or fermentation. So just because a jar is ‘sealed’, doesn’t mean that it is safe to store on your pantry shelf until winter. Always consult a current canning publication such as the Ball Blue Book or any WSU Extension canning publication for the current canning procedures and processing times.

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What kind of liquids can I use over my fruit when canning?

You can use any kind of liquid as long as it is boiling. It needs to be boiling so that when the liquid goes into the hot jar and then the hot jar goes into the hot simmering water in the water bath canner the jar won’t break. Also this will lesson the processing time. As for the liquid it can be water, sugar water, juices or juice water mixtures, or any other kinds of liquids you wish to use.

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Can I preserve Asian Pears?

Asian pears can be preserved but have a pH of about 4.5–4.8, so they need to be acidified to be safe to water bath can. To each jar you should add some bottled lemon juice. Add 1 tablespoon per pint jar and 2 tablespoons per quart jar.

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There are white deposits around the tops of my jars of canned tomatoes. Are they safe to eat?

Sometimes white dots appear around the top of the jar in canned tomato products, especially those that have added ingredients such as onion and green pepper. It occurs after the tomato product has been stored for a long period of time. There are several explanations. First it may be a mineral deposit such as calcium nitrate. If the deposit is grainy, then this maybe its origin.

Another explanation for the grainy deposit is the result of a reaction between the acid in the food and calcium carbonate in the sealing composition of the lid. Calcium acetate crystals form.

If the deposit is soapy feeling, it may be soap. There is a small amount of fat in the tomato seeds and this combines with an alkaline substance to form soap.

In all cases, the products are safe to eat as long as they were processed correctly.

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What causes lids to buckle?

Putting the screw bands on so tightly that air can hardly escape from the jars during processing. The buildup of pressure inside jars causes lids to buckle. Screw bands should be tightened firmly, by hand, So do not use a jar wrench to tighten screw bands. The best advice to is tighten the ring to finger tight. And remember when you take the jars out of the canner, the rings will be loose. DO NOT tighten them. Let them sit and cool. Then remove the rings, wash the jars and store the product without the rings.

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My pressure canner is the self-venting type. Why do other instructions say to vent all pressure canners for 10 minutes?

All pressure canners, including “self-venting” Pressure canners, do need to be vented for 10 minutes before the pressure is allowed to rise. This venting time is a way to be certain that all air is removed from the pressure canner.

Research has shown that under some conditions (particularly with raw-packed foods) all air may not be removed from self-venting pressure canners. If there is air in the pressure canner, the temperature is much lower than if the canner contains only water and steam.

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Can I use old pickle recipes?

If you do, be certain there is at least as much vinegar as water. In the past, vinegar was sold as 7% acetic acid. Commercial vinegars are now 5% acetic acid. Recipes developed for the stronger vinegar might not contain sufficient acid to be used with 5% vinegar.

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Why is it recommended to process pickles in a simmering or boiling water bath?

Processing pickles in a simmering or boiling water bath controls bacteria, yeast, and mold growth. A short processing time, combined with the acid level of the pickles, is sufficient to control these organisms. Processing also insures a good seal on the jars.

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Why should meat be pre-treated before drying into jerky?

To produce a safe product, jerky meat must be heated to 160 F prior to drying. Cases of food-borne illness associated with E.coli 0157:H7 from beef and deer jerky, and trichinosis from bear and pork meat have been documented. To be certain the jerky is safe to eat, the meat should be precooked before it is made into jerky. Additional information about jerky preparation is available the WSU Extension office.

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