Effects of food preservatives on growth and metabolism of plaque bacteria in vitro and in vivo

The aims of the present study were to assess the consumption of food preservatives during the last decades, and to study the effect of the preservatives, sorbic and benzoic acid, on growth and glycolysis of oral bacteria in vitro , and on acid formation by dental plaque in vivo . Five consumption reports from the Central Bureau of Statistics of Norway were used to estimate alterations in consumption of staple food containing the two preservatives. A modified broth dilution method was used to determine the MIC values of the preservatives against Streptococcus sobrinus and Streptococcus sanguis . Extracellular 14 C‐glycolytic metabolites were studied by HPLC analyses. Plaque‐pH measurements were used to assess possible effects on acid production. The consumption reports indicated increased consumption of preservatives. The in vitro testing suggested that legal concentrations of preservatives may inhibit the growth of oral streptococci. However, the preservatives did not inhibit in vitro glycolysis at tested concentrations. In vivo testing with similar concentrations (0.4% w/v) showed a significant effect. A higher concentration (2% w/v potassium sorbate) had a tendency to inhibit acid‐formation by dental plaque even more.