What is a low-acid tomato?

Gary Ibsen
TomatoFest Heirloom Tomato Seeds

Acidity in tomatoes can vary slightly with soil and growing conditions, but generally, all tomato varieties are below the 4.6 pH level. Some varieties, such as the whites and yellows, and certain pinks and reds, may feel like they are low-acid, but they actually have higher sugar levels that mask the acidity. Low-acid tomatoes are more a matter of perception than chemical composition.