This excerpt is from an article posted on the web by Ruth Ann Allaire, Ph.D. of Northern Virginia Community College. It also has some good instructions on how to do simple genetics tests with taste test strips.
"Sodium benzoate taste: Obtain a sodium benzoate taste strip and chew it. A different pair of alleles determines the ability to taste sodium benzoate (as opposed to PTC taste). If you can taste it, you have at least one of the dominant alleles (S). If not, you are homozygous recessive (ss) for the trait. Also record whether sodium benzoate tastes, salty, bitter, or sweet to you (if a taster). Even though PTC and sodium benzoate taste are inherited independently, they interact to determine a person's taste sensations. Individuals who find PTC bitter and sodium benzoate salty tend to be devotees of sauerkraut, buttermilk, spinach, and other slightly bitter or salty foods."
This excerpt is from an article by Louis R. Hundley, Assistant Professor of Biology, Virginia Military Institute. Like the article above, it is mainly concerned with PTC but has additional information on sodium benzoate as well.
"Sodium benzoate is another substance which can be tasted by some people but is tasteless to others. This compound in concentrations of around 0.1 per cent is sometimes used as a food preservative, but its use for this purpose is subject to controversy because some experiments led to the conclusions that benzoates were distinctly detrimental to health. State regulations regarding the use of benzoates as preservatives vary widely; some states prohibit their use, others place severe restrictions on their use, and still others have liberal regulations which control the utilization of benzoates as food preservatives. Blakeslee1 reports that a 0.1 per cent solution of sodium benzoate had a distinct taste to over a quarter of the 250 people tested. Williams14, using information received in personal communication from Arthur L. Fox, says that both tasters and non-tasters for PTC can be subdivided into five subgroups depending on whether sodium benzoate is to them (1) salty, (2) sweet, (3) sour, (4) bitter, or (5) tasteless. Fox found "that after testing about 1500 people that practically every possible combination of tastes could be found except that in which PTC was tasteless and sodium benzoate bitter. The more numerous cases were (giving the tastes in the order: PTC-sodium benzoate): (1) bitter-salty, (2) bitter-sweet, (3) bitter-bitter, (4) tasteless-salty. It further appears the 'bitter-salty' group finds the taste of a variety of foods which may be considered controversial (sauerkraut, buttermilk, turnips, spinach, etc.) more attractive than average, whereas those who are in the 'bitter-bitter' group like the taste of such foods less than average."