I made a lasagna today (Thursday) that will be served on Sunday evening. What will yield a fresher-tasting result: refrigerating or freezing? I know that lasagna keeps in the fridge for about 3-5 days, and this is about 72 hours, but will it taste better/fresher if I freeze immediately after baking? 
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.  