Hi,

You can use either method. You will be able to put more tomatoes in the jar if you use a hot pack. There will be less float.

Below is some information on tomatoes from the University of California:

TO HOT PACK TOMATOES:

Bring whole, peeled tomatoes to a boil. Pack HOT into clean, hot jars leaving 1/2 inch headspace. Cover with the hot liquid in which the tomatoes were heated. Add 1 teaspoon salt (optional) and 2 tablespoons bottled lemon juice or 3 tablespoons vinegar or 1/2 teaspoon citric acid per quart. Remove bubbles with a non-metallic spatula. Wipe rim with clean, damp cloth. Seal with prepared lids.

TO RAW PACK:
Pack raw, whole, peeled tomatoes tightly to the tops of hot jars. Press tomatoes down after each two tomatoes are added to release juice and fill spaces. Add 1 teaspoon salt (optional) and 2 tablespoons bottled lemon juice or 2 tablespoons vinegar or 1/2 teaspoon citric acid per quart. Remove bubbles. Wipe rim with clean, damp cloth. Seal with lids prepared according to manufacturer's directions.

PROCESS:
Place jars in a simmering water bath that covers the tops of the jars. Start timing when water returns to a gentle boil--200° to 210° F.

HOT PACK:Pints = 30 minutes Quarts = 30 minutes

RAW PACK:Pints = 45 minutes Quarts = 45 minutes

Cool jars, on a rack, free from drafts and undisturbed for 12 hours. Remove rings, check for seal. Wash. Label. Store in a cool, dry, dark place.

Note: Add lemon juice, citric acid or vinegar directly to the jars before filling with product, or to the top after packing. Add sugar to offset acid taste, if desired. The method for processing tomato-vegetable mixtures, such as stewed tomatoes or tomato sauce will depend on the recipe. Addition of low acid vegetables to tomatoes affects the pH and, without the addition of significant amounts of acid, requires pressure canning. Home-canned tomato juice usually separates. It is hard to duplicate at home the commercially used "hot break" extraction method.