Q:

Why do we need to preserve food?

A:

Food preservation is essential because it extends the length of time during which the food is nutritionally viable and safe to eat. Most fresh fruits, vegetables and animal products spoil quickly without refrigeration, dehydration or preservation. The Clemson Cooperative Extension states that the most popular and effective preserving techniques employ salt, sugar, vinegar or brine.

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According to the Clemson Cooperative Extension, food preservation works because the preserving agents prevent bacteria, mold and other potentially harmful organisms from growing on the food. Dry preserving techniques, such as packing food in salt, draws water out of the food, making it an inhospitable environment for microorganisms. Wet-preserved foods undergo heat processing that kills microorganisms, and the vacuum seal created by proper canning prevents life-sustaining oxygen from entering the container.

Most bacteria and fungal spores cannot live without oxygen and do not survive prolonged immersion in boiling water. A notable exception is the bacterium Clostridium botulinum, which causes a dangerous and potentially fatal disease called botulism. Clostridium botulinum is unusually hardy and thrives in anoxic environments; oxygen is toxic to it. It also survives boiling temperatures that kill most other bacteria. However, it cannot survive acidic environments such as pickle brine.

About.com expert Leda Meredith explains that non-acidic preserves such as unpickled vegetables, soup stock and all wet meat preserves do not contain sufficient acid to kill Clostridium botulinum. The only safe technique for making these preserves is to process the jars in a pressure canner, which subjects them to temperatures much higher than boiling water.

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Related Questions

  • Q:

    How do you preserve a pumpkin?

    A:

    To preserve a pumpkin, slice it into strips, remove the rind, cube and boil the flesh, pack it into jars, and process the jars in a pressure canner. This five-hour process requires a knife, a pot, water, a stove, a ladle, a towel, canning jars and a pressure canner.

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  • Q:

    How can I preserve ginger in syrup?

    A:

    To preserve ginger root in syrup, peel the ginger, and cut it into slices or chunks. Soak the ginger pieces overnight, and then boil them in a saucepan on the stove. Let the ginger simmer over low heat until it is tender enough to pierce easily with a knife. Make simple syrup in a separate, heavy-bottomed pot, letting it boil slightly until it thickens. Place the ginger and simple syrup into a sterilized jar. Store the jar in a cool, dry area.

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  • Q:

    How do you identify food-grade buckets?

    A:

    Food-grade plastic buckets are identified by the recycling symbols on the plastic and the abbreviations that tell what kind of plastic it is. Examples of marks include HDPE with recycle two, vinyl or PVC with recycle three, LDPE with recycle four, and PET (also called PETE) with recycle one. The recycling symbols are comprised of a triangle made of arrows with the number inside of it.

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  • Q:

    How long is food coloring good for?

    A:

    Food coloring is good indefinitely and does not have an expiration date. Food coloring tends to hold on to its strength in color as well. Be sure the containers stay well-sealed.

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