Susceptibility and resistance of lactic acid bacteria and yeasts against preservatives with potential application in table olives

• The inhibitory effect of 6 preservatives against table olive related microorganisms was determined.
• Fumaric acid, in the range assayed, did not show any effect against microorganisms.
• Natamycin was highly efficient for controlling yeast growth, but not against bacteria.
• Metabisulphite, pyruvic acid and cinnamaldehyde had the highest inhibitory effect on yeast and LAB.

In the present study, a dose-response model was used to investigate the susceptibility (NIC) and resistance (MIC) of the lactic acid bacteria and yeast populations with respect to five chemical preservatives (fumaric and pyruvic acids, cinnamaldehyde, sodium metabisulphite and natamycin) with potential application in table olives. Results were compared with respect to potassium sorbate, a well-known preservative habitually used in olive packaging. Sodium metabisulphite was the most efficient preservative to control lactic acid bacteria growth (MIC, 50 ppm), followed by cinnamaldehyde (1060 ppm) while pyruvic acid required higher concentrations (3211 ppm). Natamycin (25 ppm) was highly efficient against yeasts, followed by cinnamaldehyde (125 ppm), potassium sorbate (553 ppm), sodium metabisulphite (772 ppm) and pyruvic acid (3038 ppm). Fumaric acid, in the range assayed (0–2000 ppm), did not show any inhibitory effect against these two microbial groups. This survey presents for the first time a comparative study of the efficiency of potential preservatives to control the growth of table olive related microorganisms. Further studies should be performed to validate their effects and interactions in the food matrix.