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I understand that Ace 55 tomatoes are low in acid. Is it unwise to use them for canning even if Lemon Juice is added?

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A

In the 1980's several researchers studied the effects of cultivars on final acidity of canned tomatoes.  Essentially, they found that the cultivar (even ones described as "low acid") did not appreciably affect the final pH when USDA recommendations to add lemon juice or citric acid are followed.
So, the short answer is that it is safe to use the Ace 55 cultivar (or other "low acid" tomato cultivars) as long as the standard USDA recommendation for adding acid is followed:

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.

Science-based references:
Acidification reference - USDA Complete Guide to Home Canning.  http://www.uga.edu/nchfp/how/can_03/tomato_intro.html.
THOMAS J. MONTVILLE, LUCILLE K. CONWAY, and GERALD M. SAPERS. (1983) Inherent Variability in the Efficacy of the USDA Raw-Pack Process for Home-Canned Tomatoes. Journal of Food Science 48:6, 1591–1593
S. R. DRAKE and L. G. PRICE. (1982) pH AND QUALITY OF HOME-CANNED TOMATO-VEGETABLE MIXTURES1. Journal of Food Quality 5:2, 145–153
G. M. SAPERS, J. G. PHILLIPS, F. B. TALLEY, O. PANASIUK and J. CARRE. (1978) ACIDULATION OF HOME CANNED TOMATOES. Journal of Food Science 43:4, 1049–1052

Posted on 5 Sep 2007

Brian Nummer
Food Safety Specialist

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