Sprouting Aid, Makes a Great Substitute for Salt, Natural Preservative. If you\'re into sprouting then you\'re already familiar with Citric Acid, a natural preservative typically found in citrus fruits such as lemons and limes. Citric Acid helps to inhibit the formation of mold and other bacterial growth, an all-too-common occurrence when sprouting in a jar due to high temperatures and humidity. Citric Acid is also useful for canning vegetables and fruit preserves.