Tartaric Acid in a 50g tub by Almost Off Grid. Tartaric acid is an organic acid in crystal form that occurs naturally in many fruits, including grapes. If your homemade wine doesn't have enough tartaric acid it can lack flavour. If you open a bottle of well-aged red wine, you may find red crystals on the cork or stuck on the side of the bottle and this is usually a good indicator that the wine will taste soft and flavourful. Tartaric Acid can be added to juice, homemade wine or cider to achieve the acidity you want. Follow your recipe which will advise how much tartaric acid to add. Sealed in a tamper proof and resealable tub.