Is it the tase of vinegar you dislike or is it just the acidity? If its just the flavor, you can use citric acid instead.

You wouldn't add citric acid because you won't have the right density. It will be too dry. You can always use bottled lemon juice in place of vinegar. It won't taste as tart. Cutting down on the sugar is fine. You need the acid due to the tomatoes.
I would only be guessing if I told you it was safe to cut back on the acid. I wouldn't say how much to cut back.

I don't have a problem with vinegary tastes at all - I simply wanted to cut back on the sugar, and figured that without it I'd have to cut back on the vinegar to maintain a nice taste balance. Vinegar almost seems redundant, with all the high-acid fruit, but without it, it wouldn't really be chutney.

However, I recently canned an Oded Schwartz plum chutney - 2 lbs plums, 6 garlic cloves, 6 chiles to 3 cups vinegar - and found it pretty darn vinegary.

Can citric acid in water be used as a substitute for vinegar? My calculator is burried right now and I can't do the conversion for a triprotic acid on the back of an envelope, but at some point in the near future I can calculate the weight of citric acid needed to a given volume of water, although a triprotic acid will always interact with its environment differently.

A teaspoon of citric is more than sufficient for a quart of tomatoes, but if you add water to make the product less dense, you also dilute the citric. The recipes are intended for safe canning and are not very stable once major substitutions are made, such as the case of vinegar to citric. What about bottled lemon juice instead?

Brendan, I was going to ask the same thing. Can anybody say how much citric acid + a given amount of water = 5% vinegar? I bought a little packet of citric acid powder as repackaged bulk (for cheesemaking), so I don't know how strong it is to begin with - is there a standard strength? Plus, is citric acid as "acidic" as acetic acid, or ascorbic acid as in bottled lemon juice? It's been a lot of years since my last organic chemistry class.

Can citric acid in water be used as a substitute for vinegar?

In theory, yes. But not in practice because the pH of the end result wouldn't be standardized. It would depend on your water's pH which varies wildly. 1 t to a quart my well water here in "limestone heaven" would still be way on the alkaline side of the scale and so be very different from your city water.

Linda Lou's crucial point was that you need the total amount of liquid called for to control the density. Density in a recipe is just as important as pH and if you reduce the liquid you increase the density and so invalidate the processing time because you have slowed the heat penetration.

If you don't want to use the vinegar then the approved alternates are wine vinegar that is 5%, or bottled lemon juice or lime juice. You can use a mixture of any of those as long as you keep the 2 1/2 cups total the same.

Dave

Citric acid should only be used when canning recipes say to use it, not as a substitute for the other acids such as vinegar or bottled lemon juice. Partly due to the acidity, but also for the density, as I mentioned before. The only safe substitution I know of is to be able to use bottled lemon or bottled lime juice instead of 5 % acidity vinegar. Just not the other way around, because the bottled lemon juice or bottled lime juice is twice as acidic as the vinegar. It gives a more mellow taste as the vinegar.
Ascorbic acid is not meant for adding acid, more for just to prevent oxidation of foods.