No they are not. They are different acids each with different purposes and uses, especially in food preservation. Citric acid is more acidic and is used exclusively for acidifying foods that have an alkaline or borderline pH.

Ascorbic acid is less acidic, basically a vitamin, and is used exclusively for color preservation, not for acidification.

Using your examples of "tomato juice and sliced peaches" you would need both. Citric for the tomato juice and ascorbic for the peaches.

Dave

Thank you. That's helpful.

matthias, I never buy ascorbic acid like Fruit Fresh. I open/crush a couple of Vitamin C tablets or capsules and dissolve them in water to avoid oxidation in fruits like peaches or apples. Far, far cheaper and just as effective.

Citric acid is also inexpensive, I got mine at a local store which sells cheese making supplies, but it's available in larger quantities online. I can't imagine needing more than a pound or two, as I add 1/2 tsp per quart of tomatoes as suggested by NCHFP, so it goes a long way. I also use it to clean the dishwasher, but it still lasts a long time.

Annie

I saw that the NCHFP recommends crushing vitamin C tablets, too. I had thought that the recommendation came from the days when everyone could buy vitamin C at the grocery or drugstore, but no one had yet had anything like the internet to stretch the dollars with. Thought I might do better with internet ordering.

Turns out I did not order the ascorbic acid, but I did order citric acid. (I also wanted extra citric acid to use for sunscreen stain removal from my white gardening shirts. Tried it last year with enough success to want a jar for the laundry.) I think I remember seeing bulk ascorbic acid at an import grocery, so thought I look there.