pdt@mhuxv.UUCP (tyma) (04/23/84)
I'd like to clarify a few remarks recently made in this newsgroup about the role of salt in keeping coffee from becoming bitter during brewing. The comments deal with the chemistry involved. One claim was that acidity in the coffee was responsible for the bitterness. It is not likely to be the acidity per se: of the four major groups of tastes (sweet, sour, bitter, and salt), acidity is associated with "sour" while acidity's *opposite* (basicity) is associated with "bitter". Something else extracted with the acids (like caffeine or other xanthines, f'rinstance) is probably resposible for the bitterness. A second claim is that salt neutralizes acids. But while salts can be the *products* of acid-base reactions, they are not otherwise involved in the neutralization. If a substance neutralizes an acid, it is *by definition* a base, not a salt. Neither the sodium cation or the chloride anion (from salt) has any detectable acid-base chemistry in water. None of the above reflects on the accuracy of the claim that salt keeps down the bitterness in coffee. *How it works* is the issue here. Direct participation in acid-base chemistry is an unlikely explanation. However, salts can have significant effects on the extraction of organic substances into water; perhaps salt has such an effect on the extraction of the unnamed bitter-tasting species in coffee.