The effect of hydrogen-ion concentration on the toxicity of several preservatives to microorganisms

Abstract

Abstract does not appear. First page follows. In the preservation of food products commercially by means of sodium benzoate or of sulfurous acid, marked irregularities in pre servative effect have been observed. In experiments conducted in this laboratory several years ago at the request of the industries concerned, it was found that 1/10 of 1 per cent sodium benzoate failed to prevent the spoiling of ripe olives, artichokes, avocado pulp, and sliced avocadoes in brine, whereas more acid products, such as fruit juices and green olives, were preserved satisfactorily by this concentration of benzoate. In other experiments it was found that potassium metabisulfite (K2S205, the anhydride of KHSO3) was a much less effective preservative for juice from overripe grapes than for juice from slightly immature grapes. It appeared, therefore, that sodium benzoate and potassium metabisulfite are more effective as preservatives in media of high acidity than in those of low acidity. Because of these and other observations, it was suspected that the reaction of the medium, that is, its hydrogen-ion concentration, probably plays an important role in the preservation of food products by sodium benzoate and sulfurous acid (or its salts).