Inactivation of Bacillus licheniformis in liquid coffee extract by microwave heating in domestic oven and precise temperature measurements using an optical fiber sensor

Abstract

This study evaluates the inactivation of Bacillus licheniformis in liquid coffee extract using heating microwaves. To achieve accurate measurements of temperatures, an optical fiber sensor was developed and calibrated for real-time and in situ measurements of the extract. Using a central composite design, the effects of the processing time, power levels and sample volume were evaluated together with the concentration of the soluble solids of the liquid coffee extract and the position of the sample in the microwave cavity. In addition, the physicochemical and sensory properties of the product were evaluated. The results indicate that the greatest reduction of the microorganism occurred when the processing time was 19 seconds at a power level of 6 using a sample volume of 11 mL and that the highest biological destruction occurs when the sample is placed in the center of the microwave cavity.

Keywords

• microwave
• coffee extract
• Bacillus licheniformis
• inactivation