Place the required number of clean 500 ml, 750 ml or 1 L mason jars on a rack in a boiling water canner. Cover jars with water and heat to a simmer (180°F/82°C). Set screw bands aside. Keep jars hot until ready to use. Preheating Bernardin® lids is not advised.

The sealing compound used for our home canning lids performs better at room temperature than it does pre-heated in simmering water (180°F). Simply wash lids in hot, soapy water, dry, and set aside until needed.

Preheating can lead to less vacuum being achieved during water bath canning, and to buckle failures during pressure canning. Wash and blanch tomatoes. Slip off skins; remove cores and any bruised or discoloured portions. Leave whole or halve. Place tomatoes in a large stainless steel saucepan.

Add enough tomato juice to cover; bring to a boil; boil gently for 5 minutes. Add quantity of lemon juice or citric acid specified below to each hot mason jar before packing tomatoes. If using, add salt to jar prior to filling.

Jar size Lemon juice or Citric acid Salt, optional 500 ml 1 tbsp (15 ml) or 1/4 tsp (1 ml) 1/2 tsp (2 ml) 1 L 2 tbsp (30 ml) or 1/2 tsp (2 ml) 1 tsp (5 ml) Pack tomatoes into a hot jar to within 3/4 inch (2 cm) of top rim.

Add hot juice to cover tomatoes to within 1/2 inch (1 cm) of top of jar (headspace). Using nonmetallic utensil, remove air bubbles and adjust headspace, if required, by adding more tomatoes and hot liquid. Wipe jar rim removing any food residue. Centre hot sealing discs on clean jar rim.

Screw band down until resistance is met, then increase to fingertip tight. Return filled jar to rack in canner. Repeat for remaining tomatoes and hot liquid. When canner is filled, ensure that all jars are covered by at least one inch (2.5 cm) of water.

Cover canner and bring water to full rolling boil before starting to count processing time.

At altitudes up to 1000 ft (305 m), process-boil filled jars- Jar size Processing time* 500 ml 85 minutes 750 ml 85 1 L 85 minutes When processing time is complete, remove canner lid, wait 5 minutes, then remove jars without tilting and place them upright on a protected work surface.

Cool upright, undisturbed 24 hours; DO NOT RETIGHTEN screw bands. After cooling check jar seals. Sealed discs curve downward and do not move when pressed. Remove screw bands; wipe and dry bands and jars. Store screw bands separately or replace loosely on jars, as desired.

Label and store jars in a cool, dark place. For best quality, use home canned foods within one year.

Processing: At altitudes up to 1000 ft (305 m), process-boil filled jars- Jar size Processing time* 500 ml 85 minutes - 85 minutes.

Altitude-adjusted processing table: At altitudes up to 1000 ft (305 m), process-boil filled jars- Jar size Processing time* 500 ml 85 minutes