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A. No, oven canning is dangerous. Jars may explode. The temperature of the food in jars during oven processing does not get high enough to insure destruction of spoilage bacteria in vegetables. U.S.D.A. 1976. Home Canning of Fruits and Vegetables. Home and Garden Bulletin No. 8. (Issued February 1965, Slightly revised May 1976). United States Department of Agriculture, Washington, D.C. |
Q. Why is open-kettle canning not recommended for fruits and vegetables?
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A. In open-kettle canning, food is cooked in an ordinary kettle, then packed into hot jars and sealed without processing. For vegetables, the temperatures obtained in open-kettle canning are not high enough to destroy all the spoilage organisms that may be in the food. Spoilage bacteria may get in when the food is transferred from kettle to jar. U.S.D.A. 1976. Home Canning of Fruits and Vegetables. Home and Garden Bulletin No. 8. (Issued February 1965, Slightly revised May 1976). United States Department of Agriculture, Washington, D.C. |
Q. May a pressure canner be used for processing fruits and tomatoes?
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A. Yes. If it is deep enough it may be used as a water-bath canner. Or you may use a pressure canner to process fruits and tomatoes at 0 to 1 pound pressure without having the containers of food completely covered with water. Put water in the canner to the shoulders of the jars; fasten cover. When live steam pours steadily from the open vent, start counting time. Leave vent open and process for the same times given for the boiling-water bath. U.S.D.A. 1976. Home Canning of Fruits and Vegetables. Home and Garden Bulletin No. 8. (Issued February 1965, Slightly revised May 1976). United States Department of Agriculture, Washington, D.C. |
Q. Must glass jars and lids be sterilized by boiling before canning?
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A. No, not when boiling-water bath or pressure-canner method is used. The containers as well as the food are sterilized during processing. But be sure jars and lids are clean. U.S.D.A. 1976. Home Canning of Fruits and Vegetables. Home and Garden Bulletin No. 8. (Issued February 1965, Slightly revised May 1976). United States Department of Agriculture, Washington, D.C. |
Q. Why is liquid sometimes lost from glass jars during processing?
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A. Loss of liquid may be due to packing jars too full, fluctuating pressure in a pressure canner, or lowering pressure too suddenly. U.S.D.A. 1976. Home Canning of Fruits and Vegetables. Home and Garden Bulletin No. 8. (Issued February 1965, Slightly revised May 1976). United States Department of Agriculture, Washington, D.C. |
Q. Should liquid lost during processing be replaced?
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A. No, never open a jar and refill with liquid-this would let in bacteria and you would need to process again. Loss of liquid does not cause food to spoil, thogh the food above the liquid may darken. U.S.D.A. 1976. Home Canning of Fruits and Vegetables. Home and Garden Bulletin No. 8. (Issued February 1965, Slightly revised May 1976). United States Department of Agriculture, Washington, D.C. |
Q. Is it safe to use home canned food if liquid is cloudy?
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A. Cloudy liquid may be a sign of spoilage. But it may be caused by the minerals in hard water, or by starch from overripe vegetables. If liquid is cloudy, boil the food. Do not taste or use any food that foams during heating or has an off odor. U.S.D.A. 1976. Home Canning of Fruits and Vegetables. Home and Garden Bulletin No. 8. (Issued February 1965, Slightly revised May 1976). United States Department of Agriculture, Washington, D.C. |
Q. Why does canned fruit sometimes float in jars?
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A. Fruit may float because pack is too loose or sirup too heavy; or because some air remains in tissues of the fruit after heating and processing. U.S.D.A. 1976. Home Canning of Fruits and Vegetables. Home and Garden Bulletin No. 8. (Issued February 1965, Slightly revised May 1976). United States Department of Agriculture, Washington, D.C. |
Q. Is it safe to can foods without salt?
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A. Yes. Salt is used for flavor only and is not necessary for safe processing.
U.S.D.A. 1976. Home Canning of Fruits and Vegetables. Home and Garden Bulletin No. 8. (Issued February 1965, Slightly revised May 1976). United States Department of Agriculture, Washington, D.C. |
Q. What makes canned foods change color?
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A. Darkening of foods at the tops of jars may be caused by oxidation due to air in the jars or by too little heating or processing to destroy enzymes. Overprocessing may cause discoloration of 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 or from water in some localities may cause brown, black, and gray colors in some foods. When canned corn turns brown, the discoloring may be due to the variety of corn, to stage of ripeness, to overprocessing, or to copper or iron pans. Packing liquid may dissolve coloring materials from the foods. The use of plain tin cans will cause some foods to lose color. U.S.D.A. 1976. Home Canning of Fruits and Vegetables. Home and Garden Bulletin No. 8. (Issued February 1965, Slightly revised May 1976). United States Department of Agriculture, Washington, D.C. |
Q. Is it safe to eat discolored canned foods?
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A. The color changes noted above do not mean the food is unsafe to eat. However, spoilage may also cause color changes. Any canned food that ha an unusual color should be examined carefully before use. U.S.D.A. 1976. Home Canning of Fruits and Vegetables. Home and Garden Bulletin No. 8. (Issued February 1965, Slightly revised May 1976). United States Department of Agriculture, Washington, D.C. |
Q. Does ascorbic acid help keep fruits and vegetables from darkening?
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A. Yes. The addition of 1/4 teaspoon of crystalline ascorbic acid (vitamin C) to a quart of fruit or vegetable before it is processedc retards oxidation, which is one cause of darkening of canned foods. One teaspoon of crystalline ascorbic acid weighs about 3 grams (or 3,000 milligrams). Ascorbic acid preparations containing sugar can be used with fruits in proportions suggested by manufacturer. U.S.D.A. 1976. Home Canning of Fruits and Vegetables. Home and Garden Bulletin No. 8. (Issued February 1965, Slightly revised May 1976). United States Department of Agriculture, Washington, D.C. |
Q. Is it all right to use preservatives in home canning?
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A. No. Some canning powders or other chemical preservatives may be harmful. U.S.D.A. 1976. Home Canning of Fruits and Vegetables. Home and Garden Bulletin No. 8. (Issued February 1965, Slightly revised May 1976). United States Department of Agriculture, Washington, D.C. |
Q. Why do the undersides of metal lids sometimes discolor?
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A. Natural compounds in some foods corrode the metal and make a brown or black desposit on the underside of the lid. This deposit is harmless. U.S.D.A. 1976. Home Canning of Fruits and Vegetables. Home and Garden Bulletin No. 8. (Issued February 1965, Slightly revised May 1976). United States Department of Agriculture, Washington, D.C. |
Q. When canned or frozen fruits are bought in large containers, is it possible to can them in smaller containers?
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A. Any canned or frozen fruit may be heated through, packed, and processed the same length of time as recommended for hot packs. This canned food may be of lower quality than if fruit had been canned when fresh. U.S.D.A. 1976. Home Canning of Fruits and Vegetables. Home and Garden Bulletin No. 8. (Issued February 1965, Slightly revised May 1976). United States Department of Agriculture, Washington, D.C. |
Q. Is it safe to leave food in tin cans after opening?
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A. Yes. Food in tin cans needs only to be covered and refrigerated. U.S.D.A. 1976. Home Canning of Fruits and Vegetables. Home and Garden Bulletin No. 8. (Issued February 1965, Slightly revised May 1976). United States Department of Agriculture, Washington, D.C. |
Q. Is the processing time the same no matter what kind of range is used?
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A. Processing times and temperatures in this bulletin are for canning in a pressure canner or boiling-water bath with any type of range. U.S.D.A. 1976. Home Canning of Fruits and Vegetables. Home and Garden Bulletin No. 8. (Issued February 1965, Slightly revised May 1976). United States Department of Agriculture, Washington, D.C. |
Q. Can fruits and vegetables be canned without heating if aspirin is used?
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A. No. Aspirin cannot be relied on to prevent spoilage or to give satisfactory products. Adequate heat treatment is the only safe procedure. U.S.D.A. 1976. Home Canning of Fruits and Vegetables. Home and Garden Bulletin No. 8. (Issued February 1965, Slightly revised May 1976). United States Department of Agriculture, Washington, D.C. |
