Looking for a little pucker power but out of fresh lemon? Try sour salt. This white powder was once a staple in Eastern European cupboards because lemons were not common.
Sour salt is citric acid, a powder extracted from acidic fruits. The flavour is acutely sour. It is inexpensive and a small jar lasts for years. A few grains have as much tartness as a couple of squeezes from a lemon or lime but the salt doesn't have a strong fruit flavour. Keep some for when a recipe calls for lemon juice and there isnt any in the house or when using lemon juice in cake or muffin recipe would change the balance of dry to wet ingredients.
Sour salt works best in recipes that also include sugar but the objective is to create a pleasant balance between the sweet and sour such as in cold beet borscht or a lemony cheese cake. I also find that sour salt tastes fresher than bottled or concentrated lemon or lime juice.