Monday, 2 July 2007

Cordial Chemistry

This post is about some of the ingredients typically found in soda/ cordial drinks. So far I've just used citric acid and campden tablets (sodium metabisulphite E223, Polethylene Glycol) in the cordials I've made, but I want to get an understanding of what's out there so that I have a better idea of what I'm doing/ need to do.

Sodium Citrate (acidity regulator) is the sodium salt of citric acid with the chemical formula of Na3C6H5O7. Sodium citrate possesses a saline, mildly tart, flavor. For this reason, citrates of certain Alkaline and Alkaline Earth metals (e.g. sodium and calcium citrates) are commonly known as sour salt (occasionally citric acid is erroneously termed sour salt). Sodium citrate is chiefly used as a food additive, usually for flavor or as a preservative. Sodium citrate is employed as a flavoring agent in certain varieties of club soda. Sodium citrate is common in lemon-lime soft drinks, and it is partly what causes them to have their sour taste.
More about sodium citrate on Wikipedia >

Citric Acid is a weak organic acid found in citrus fruits. It is a natural preservative and is also used to add an acidic (sour) taste to foods and soft drinks. In biochemistry, it is important as an intermediate in the citric acid cycle and therefore occurs in the metabolism of almost all living things. It also serves as an environmentally benign cleaning agent and acts as an antioxidant. Citric acid exists in a variety of fruits and vegetables, but it is most concentrated in lemons and limes, where it can comprise as much as 8% of the dry weight of the fruit.
More about citric acid on Wikipedia

Sodium Benzoate (E211, preservative), also called benzoate of soda, has chemical formula C6H5COONa. It is the sodium salt of benzoic acid and exists in this form when dissolved in water. It can be produced by reacting sodium hydroxide with benzoic acid. Sodium benzoate is used as a preservative, effectively killing most yeasts, bacteria, and fungi. It is effective only in acidic conditions (pH < 3.6) making its use most prevalent in foods such as preserves, salad dressings (vinegar), carbonated drinks (carbonic acid), jams (citric acid), fruit juices (citric acid), pickles (vinegar), and Chinese food sauces (soy, mustard, and duck). It is also found in alcohol-based mouthwash and silver polish. Sodium benzoate is used in many soft drinks and can be identified on the label of the bottle or can as 'sodium benzoate' or E211. The taste of sodium benzoate cannot be detected by around 25 percent of the population, but for those who can taste the chemical, it tends to be perceived as sweet, salty, or sometimes bitter.
More about sodium benzoate on Wikipedia

Sodium Metabisulphite or sodium pyrosulfite (American spelling; English spelling is Sodium metabisulphite or sodium pyrosulphite) is an inorganic compound of chemical formula Na2S2O5. The name is sometimes referred to as disodium (metabisulfite, etc). It is used as a sterilizer and antioxidant/preservative. It is used as a food additive, mainly as a preservative and is sometimes identified as E223. As an additive, it may cause allergic reactions, particularly skin irritation, gastric irritation and asthma. It is not recommended for consumption by children.
More about sodium metabisulphite on Wikipedia

Polethylene Glycol Pure polyethylene glycol HO(CH2CH2O)nH (PEG) have been characterized as clear viscous liquid (molecular weight less than 200), wax-like substance (molecular weight 200 ÷ 2000) and as opaque white crystalline solid (higher molecular weight). Polyethylene glycols are soluble in most organic solvents, such as benzene, carbon tetrachloride, chloroform, dimethylformamide (DMF), acetonitrile. PEG is perfectly soluble in water, but solubility decreases with molecular weight of polymer increasing.
More about polethylene glycol at
Share on Facebook


  1. PEGs are added to sodas purely to alter consistency/viscosity. If you want to stick with more natural ingredients, you can use honey or glycerine (which is the same thing as glycerin and glycerol). Glycerine and PEGs are slightly laxative, though, put little enough is used in a beverage it shouldn't present a problem.

    Interestingly, both PEGs and glycerine are present in wines, and responsible for the viscosity referred to by sommeliers as "legs".

  2. Just thought I'd mention that sodium benzoate has been a bit contentious recently, especially for children under three, pepsi has banned it and the EU was condemned for not restricting it. some say it irritates skin and eyes, some say it alters dna, others that it reforms to become benzene (petrol) in the blood. try searching for 'sodium benzoate banned' its quite interesting.