Michigan State University Extension
Preserving Food Safely - 01600872
QUALITY: Select only disease-free, preferably vine- ripened, firm fruit for canning. CAUTION: DO NOT CAN TOMATOES FROM DEAD OR FROST-KILLED VINES. Green tomatoes are more acidic than ripened fruit and can be canned safely with any tomato procedure.
ACIDIFICATION: To ensure safe acidity in whole, crushed, or juiced tomatoes, add two tablespoons of bottled lemon juice or 1/2 teaspoon of citric acid per quart of tomatoes. For pints, use one tablespoon bottled lemon juice or 1/4 teaspoon citric acid. Acid can be added directly to the jars before filling with product. Add sugar to offset acid taste, if desired. Four tablespoons of a 5 percent acidity vinegar per quart may be used instead of lemon juice or citric acid. However, vinegar may cause undesirable flavor changes.
RECOMMENDATION: Use of a pressure canner will result in higher quality and more nutritious canned tomato products.