Wow that is very deep. One needs a lot of money to buy the commercial additives/preservatives here too.
Will using lemon juice help cakes stay for like say a week for the home baker?
@Akos, Lemon juice contains citric acid which is used commercially as a preservative. However, most commercial citric acid is not from a natural source (citrus fruit), rather it is created from a mold by fermenting a raw material high in starch/carbohydrate.
Most commonly mold is created using molasses, then the mold is fed a starch, normally corn starch. Personally I think it’s pretty gross so I avoid product with citric acid in them.
About 90% of the citric acid used commercially is artificially made in this way. Because it is artificially made and a powder, it’s concentration as well as it’s properties will differ from using fresh lemon juice. So while fresh lemon juice does contain citric acid, the unknowns are in what concentration is fresh lemon juice an effective preservative; will the amount required change the flavor of the cake; will the addition of it change the chemical balance of the batter? I just don’t know what the answer to these questions are.
The other considerstion is citric acid from a natural source (lemon juice) will decompose at high temperatures. A cake will bake to approximately 205°F - 210°F and pretty much total decomposition of citric acid happens at 345°F. So the question is how much, if any, decomposition happens at the temperatures that cake is baked. I’m sorry Akos, I just don’t know the answer to these questions. So I really can’t advise you as to whether or not fresh lemon juice is actually going to be an effective preservative for commercial production.