Evaluation of the nisin as inactivator substance of Bacillus licheniformis to coffee liquid extract

Objective. To evaluate the effect of nisin on the inactivation of Bacillus licheniformis to coffee liquid extract. Materials and methods. The action of nisin on Bacillus licheniformis into liquid coffee extracts was evaluated by varying its concentration, incubation time, concentration of soluble solids (°Brix) and bacterial contaminant concentration. Results. The results indicated that the concentration of nisin to achieve the inhibitory effect without affecting the physicochemical and sensory properties of the product is 500 IU/ml corresponding to 12.5 mg/L. Additionally, High levels of nisin 1000 IU/ml can act successfully in bacterial populations lower than 5x104 CFU/ml over a period of 48 hours. Furthermore, the concentration of soluble solids did not show a statistically significant effect for values from 15 to 45 °Brix. Conclusions. From this study it can be concluded that nisin may be used as a preservative in liquid coffee extract without sensorially affecting the product, taking into account the bacterial contaminant concentration and incubation time.