In place of cream of tartar to stabilize egg whites

3 grams (contingent on the relative weight of the rest of the recipe) is not a big deal.

But, since egg whites are such a pain to measure, it's very simple in recipes like this. Beat your egg whites slightly, then weigh and remove three grams. Much easier.

Ingredient substitution lists say you can use an equal volume of lemon juice or vinegar if you don't have cream of tartar.

Most likely, the assumption has been that a baker will be more likely to have cream of tartar on hand than other acid sources due to the fact that it has multiple uses in the kitchen:

• Leavening
• Stabilization of egg whites
• Prevent crystallization of sugar in things like frostings, syrups, chocolates, etc.

Cream of tartar also has a number of beneficial properties:

• It is odorless and practically tasteless, unlike lemon juice or vinegar.
• It acidifies without adding water, which might be detrimental in some applications.
• Unlike fresh lemons, cream of tartar has a nearly indefinite shelf life.