The word a(/lmh is used principally of the 'salt sea' (cf. alpha 1304), but also of the brine used for preserving fish, meat and vegetables (Herodotus 2.77; LSJ at web address 1). Galen lists three main types of preserving (web address 2) meat from putrefaction: salt, brine, vinegar (de Temperamentis 1.533 Helmreich, cf. De simplicium medicamentorum temperamentis ac facultatibus 1.12.377.10f. Kuehn vol. 11, Peri\ a(/lmhs). Presumably brine is distinguished from salt as being a solution in which the meat is plunged.
Athenaeus also uses the word frequently for the spicey, salted pickle or sauce in which a cook prepares his dish, either in cooking or in marinading it (cf. roll-mops).
It is not certain in which of these senses the word is used as a metaphor for human character. This entry takes it for the opposite of a sour, crabbed character (LSJ entry at web address 3), but at phi 379 Aeschylus's nephew is nicknamed Halmion because of his bitterness, pikri/a. J. Taillardat discusses Aristophanes' use of 'vinegar' as a metaphor for a bitter character (Les Images d'Aristophane, 1965, 197-98). When Cratinus (fr. 6 Kock and Kassel-Austin) calls Archilochus "the marinade of Thasos", who 'bow wows' (bau/zei, of the snarling or barking of an angry dog), it seems certain that he refers to his evident bitterness in attacking his victims, rather than to his wit.
Yet any reading of Athenaeus will show the delight his diners take in the sauces in which their food is rendered tastier, less boring. This entry states clearly that the man who has no sauce is sour and unpleasant, implying that a man with sauce to his wit is never bitter or rude, no matter how cruel it is. This judgment is shared by many modern sophisticated societies.
This proverb also occurs in Eustathius's note to Odyssey 4.511 and in several of the late paroemiographers (e.g. Gregorius 1.25).