There are basically four generally accepted methods for preserving foodstuffs and these methods rely
on one or the other methods of microorganism control. 1) Sterilization by heat or radiation destroys the
microorganisms; 2) refrigeration reduces or stops the activity of microorganisms; 3) drying reduces or
stops the activity of the microorganism by removing essential water; and 4) chemical preservatives
reduce or inhibit the activity of the microorganisms.
The addition of chemical preservatives to food is not new and been practiced for centuries. Some of
the most familiar preservation methods, those of brining, pickling with vinegar, smoking, and preserving
with sugar solutions, depend upon chemical preservatives. These methods inhibit microorganism
activity and retard microorganism growth and multiplication. These methods act in one of two
generalized ways: 1) by physically increasing the density of the microorganisms environment (raising
the osmotic pressure) or 2) chemically, by a direct inhibiting action on the microorganism themselves.
Consequently, chemical preservatives which perform by a direct inhibiting action on the
microorganisms themselves are not new. Sodium benzoate is a chemical preservative which in very
low concentration inhibits the activity of the microorganisms themselves.
Sodium benzoate is a food preservative that has been in use for years. As early as 1909, the
“harmlessness” of sodium benzoate as a food preservative was extensively verified in actual human
feeding studies performed by three independent research organizations under the direction of the
Secretary of Agriculture. A summary of these studies was published in a 784 Page book titled Report
No. 88 of the US Dept. of Agriculture. This report verified that sodium benzoate, when mixed with food
in the quantities specified, was not injurious to the general health nor found to adversely affect or impair
the quality or nutritive value of such food.
For a long time, sodium benzoate has been generally recognized as safe (GRAS) as a direct food
additive and recently this status was reaffirmed (21 CFR §184.1733) for use as an antimicrobial agent,
as defined in 21 CFR §170.3(o)(2), and as a flavoring agent and adjuvant, as defined in 21 CFR
§170.3(o)(12). Sodium benzoate may be used in food at levels not to exceed good manufacturing
practice. Current usage results in a maximum level of 0.1 % in food.
Sodium benzoate is most suitable for use as an antimicrobial agent in foods and beverages which
naturally are in the pH range below 4.5 %, or can be brought into the range by addition of a water
soluble acidulant. Sodium benzoate is not recommended as a preservative at pH ranges higher than
4.5.
The effectiveness of sodium benzoate as a preservative increases with decreasing pH (increasing
acidity). This is because the ratio of undissociated (i.e., free) benzoic acid to ionized benzoic acid
increases as the pH decreases. It is generally accepted that the undissociated benzoic acid is the
active antimicrobial agent. Although no definite theory has been yet proposed to explain this
antimicrobial effect, it is believed to be related to the high lipoid solubility of the undissociated benzoic
acid which allows it to accumulate on the cell membranes or on various structures and surfaces of the
bacterial cell, effectively inhibiting its cellular activity.
Sodium benzoate has activity against yeast, mold, and bacteria. Although several studies have been
performed on the antimicrobial activity of sodium benzoate on these species, it is difficult to obtain
substantial evidence on relative activities of sodium benzoate against specific members of those
general species. Actual field application trials are recommended for assurance of satisfactory
antimicrobial activity against the species in question.