- CAS # 77-92-9 (anhydrous), 5949-29-1 (monohydrate)
- FW 192.13 g/mol
- Solubility 750 g/l
- pKa 3.13 (first stage), 4.76 (second stage), 6.4 (third stage)
Citric acid plays a central role in the metabolism of all oxen-consuming lifeforms including humans. Therefore, it is widely present, sometimes in relatively high concentrations (lemons). Citric acid is industrially produced on a huge scale, using fermentation processes of sugary residues, which often employ genetically modified organisms. Therefore, the industrial citric acid is “natural.” Industrially produced citric acid can vary greatly in quality, because they may contain mycotoxins that are shed by the micro-organisms that produce citric acid. It is highly important to get confirmation from the seller that the product is food grade. When making purchases in a store, don’t be satisfied with sales people telling you that it is – ask to see the Certificate of Analysis of that particular batch (most likely those sales people have never heard that this exists).
Citric acid is relatively cheap, but has a somewhat sharp taste, so it is not ideal for acidity correction in wine. Citric acid largely survives the action of wine yeast, and also largely the ageing process of wine. In other words, the acidity born from the citric acid in wine does not change much with time.