Can Heirloom Tomatoes be 'Low Acid'?

Do you love tomatoes but get that burning feeling after eating them? Looking for an 'acid-free' tomato? You may be out of luck sorry. 

When we talk about acidity in tomatoes, we’re really talking about a small group of organic acids that naturally accumulate in the fruit during development. Citric Acid - the primary acid in tomatoes and the largest contributor to their bright, tangy flavor; and Malic Acid which is present in smaller amounts but still important to the overall acid profile.

Together, these two compounds account for the vast majority of measurable acidity in fresh tomatoes. In flavour chemistry studies, researchers often report the total organic acids as the sum of citric and malic acid, which provides a convenient way to compare varieties. 

The idea of a truly "low acid ir acid-free" heirloom tomato is largely a myth as almost all tomatoes sit within a very tight, acidic pH range of 4.1 to 4.7. Tomatoes that taste mild, or seem to be lower in acid, actually have a higher sugar content which masks the tangy-ness of the variety.

Paste and Oxheart varieties have denser flesh and less seeds which means you don't get the tartness in the flavour profile. And yellow and orange varieties taste sweeter and milder due to higher sugar levels and less intense pigments so don't 'feel' as acidic but probably are. Larger pink varieties are more likely to be lower in acid and cherry tomatoes higher.

A little trick Italians use when cooking tomatoes is to grate or add a finely chopped carrot, or add a whole peeled carrot while cooking and remove later - this is supposed to absorb the tartness.

Some of our 'lower acid' varieties are:

• Isle of Capri
• Orange Russian
• Dalmatian Oxheart
• White Wonder
• Orange Icicle
• Cherokee Purple
• Giant Belgium
• San Marzano
• Cuore de Toro
• Black from Tula

How about trying one you haven't tried before, you might be surprised.