THE CANNING equipment you will need depends on which food you are planning to process. High-acid foods, such as tomatoes and fruit, can be processed in a water-bath canner. Low-acid foods (almost all vegetables--beets, okra, corn, sweet potatoes, etc.) must be processed in a pressure canner in order to kill botulism spores. The one exception to this rule is if you add acid to low-acid items such as vinegar to cucumbers to make pickles, says JoAnne Barton, a foods and nutrition extension specialist.

A water-bath canner generally costs around $8 to $14. However, Barton says any large, deep container can be used if you want to spare the expense. The pan must have a lid, a rack and should allow two to four inches above the top of the jars being processed so the water can boil freely.

A new pressure canner generally costs around $75, Barton said. However, they are often found at garage sales for around $5 or $10. Be sure, Barton warns, that it has all of its parts: In addition to the pan with a lid that locks in place, there should be a weighted or dial temperature gauge (to control pressure in the pan during processing), a rubber gasket around the lid (to seal in steam around top), a valve or petcock (to control release of steam), a rack (to allow hot water to move underneath cans) and a safety plug (to prevent disasters; in case everything else breaks down, it melts when pressure gets too high).

Dial gauges should be checked annually. Extension offices will perform a safety check to make sure your pressure canner is in working order. (Call to find out when and where.)

Extension agents recommend that canners equip themselves with a jar lifter and funnel (both very important), lipped ladle, strainer, measuring spoons and blanching basket.

Jars come in various shapes and sizes. Mason jars, the most widely used, come in four sizes: half-pint, pint, quart and half gallon. Standard mouth jars seal on the top or neck; wide mouth jars seal on top. The two-piece metal top, a "screw-band combination," is fitted with a sealing compound around the lid that can be used only once.

Jars only need to be clean, not sterilized, if they are to be processed. (Jams and jellies, please note, must be stored in sterilized jars.)

With all the equipment checked and clean jars on hand, you're ready to begin stocking your shelves for next winter:

For the water bath canner:

* Fill canner half full and begin heating water.

* Clean and trim produce.

* Packing process is a matter of choice. Food can be hot or cold (raw) packed. Hot pack, however, is slightly more desirable because it helps ensure that more of the air bubbles are removed. To hot pack: Cover the produce with water and bring to a boil. After boiling for recommended time (usually a couple of minutes), pour food along with heating liquid into jars, leaving recommended head space. To cold pack: Simply pack raw produce into jar and cover with boiling water to recommended head space. Note, however, that precise preparation directions vary for all food. Write for one of the recommended publications listed on Page E17 for specific methods and processing times.

* Run a rubber spatula or knife between produce and jar to remove any air bubbles. Screw lid firmly in place, but not so tight that it will buckle during processing.

* Place jars on rack in canner. Add additional boiling water to bring water level one inch over the top of the jars. Cover and return to boil. When at a full boil start processing time.

* Use a jar lifter to remove from canner. Cool top-side up on a rack or folded cloth.

For the pressure canner:

* Clean and trim vegetables or fruit.

* Packing is up to the individual. Food can be hot or cold (raw) packed. Hot pack, however, is slightly more desirable because it helps ensure that more of the air bubbles are removed. To hot pack: Cover the produce with water and bring to a boil. After boiling for recommended time, pour food along with heating liquid into jars, leaving recommended head space. To cold pack: Simply pack raw produce into jar cover with boiling water to recommended head space. Note, however, that specific directions vary for all food. Write for one of the recommended publications listed on Page E17 for specific methods and processing times.

* Run a spatula around the side of the jar to remove any air bubbles. Screw lid firmly in place, but not so tight that it will buckle during processing.

* Fill canner with 2 to 3 inches of water and place jars close together, but not touching, in canner. Lock lid on pan securely.

* Leave petcock open or weighted gauge off until steam is coming out in a steady stream (usually takes about 10 minutes). Close the vent or put gauge in place.

* Watch gauge and when canner reaches desired temperature reduce heat to maintain steady pressure. You will need to monitor the canner during the entire process to ensure that pressure stays at proper level.

* When processing time is up, turn off heat and remove pan from stove. When pressure gauge drops to zero or when weighted gauge has stopped hissing, remove lid. Be sure to avert your face before removing lid, lifting back edge first to let out any excess steam. Set jars top-side-up on a rack or folded cloth to cool.

* Check seal on the jars the next day by pressing the center of the lid (it should stay down) or by tapping with a spoon (you should hear a clear, ringing sound).

Here are a few recipes to help get you started. TO PRESSURE CAN GREEN BEANS

Wash beans and drain. Cut or break off ends; cut or break into 1- or 2-inch pieces. Slice lengthwise for french-style beans.

Raw Pack: Pack raw beans tightly to 1/2-inch below top. Add 1/2 teaspoon salt, if desired, to pint jars; 1 teaspoon to quarts. Cover with boiling water, leaving 1/2-inch headspace. Remove air bubbles by running spatula or knife between food and jar. Adjust jar lids. Process in pressure canner at 10 pounds pressure (240 degrees); pint jars for 20 minutes, quart jars for 25 minutes.

Hot Pack: Cover beans with boiling water and cook for 5 minutes. Pack hot beans loosely to 1/2-inch top of jar. Add 1/2 teaspoon salt, if desired, to pint jars; 1 teaspoon to quarts. Cover with boiling hot liquid, leaving 1/2-inch headspace. Adjust jar lids. Process in pressure canner at 10 pounds pressure (240 degrees); pint jars for 20 minutes, quart jars for 25 minutes. TO WATER BATH TOMATOES

Select tomatoes which are well formed, smooth, well ripened and reasonably free from blemishes. Avoid overripe and bruised tomatoes with sunburn (green or yellow areas near the stem scar) and growth cracks (deep cracks around the stem scar). Avoid decayed tomatoes that have soft, water-soaked spots, depressed areas or surface mold.

Wash tomatoes. Loosen skins by dipping tomatoes into boiling water for about 1/2 minute; then into cold water. Skins should slip off easily. Remove stem scar and core. Leave tomatoes whole or cut into halves or quarters.

Raw pack: Pack tomatoes to 1/2-inch below top, pressing gently to fill spaces. Tomatoes will make their own juice. Do not add water as it dilutes the flavor. Add 1/2 teaspoon salt, if desired, to pint jars; 1 teaspoon to quarts. Remove air bubbles by running spatula or knife between jar and food. Adjust jar lids. Process in boiling water-bath canner (212 degrees); pint jars for 35 minutes, quart jars for 45 minutes.

Hot pack: Bring tomatoes to a boil; stir to keep from sticking. Pack boiling hot tomatoes in jars leaving 1/2-inch headspace. Add 1/2 teaspoon salt, if desired, to pint jars; 1 teaspoon to quarts. Remove air bubbles by running spatula or knife between jar and food. Adjust jar lids. Process in boiling water-bath canner (212 degrees); pint jars for 10 minutes, quart jars for 10 minutes. ZUCCHINI RELISH (Makes 6 to 7 pints) 10 cups squash, ground 4 cups onion, ground 1 cup sweet red pepper, ground 1 cup green pepper, ground 5 teaspoons salt 2 1/4 cups white vinegar 4 1/2 cups sugar 1 tablespoon nutmeg 1 tablespoon dry mustard 1 tablespoon tumeric 1 tablespoon cornstarch 2 teaspoons salt 1/2 teaspoon pepper

Mix together squash, onion, red and green peppers and salt. Let stand overnight. The next day drain, rinse and drain again. Put in kettle and add remaining ingredients. Bring to a boil and simmer 30 minutes, uncovered. Fill hot jars leaving 1/3-inch headspace. Process in boiling water bath for 10 minutes. NO MEAT MINCEMEAT (4 pints)

A good recipe for fall, when cold weather threatens tomato plants and apples and pears are in season. 4 green tomatoes 3 large apples, peeled, cored and seeded 3 pears, cored 1 orange, peeled and seeded 2 lemons, halved and seeded 2 1/2 cups raisins 2 cups brown sugar, packed 1/2 cup dark corn syrup 3/4 cup (or more) brandy 1/3 cup cider vinegar 1 tablespoon cinnamon 3/4 teaspoon each nutmeg, gloves, ginger and allspice 1/2 teaspoon salt

Put tomatoes, apples, pears, orange and lemons in food processor to chop (process each separately). Combine fruits in large kettle. Add raisins, sugar, corn syrup, brandy and vinegar. Heat to boiling and simmer 30 minutes, until thick, stirring often. Add spices, simmer 5 more minutes. Pour into hot jars, leaving 1/2-inch headspace and seal. Process in a boiling water bath 25 minutes.