Decontamination of spices by using a pulsed light treatment

Spices and aromatic herbs are widely used in different food branches and recently, industrialists from the agro-food field have started paying attention to the microbiological quality of these products. Microbial contaminants susceptible to be present at the surface of spices can potentially induce various pathologies in humans. The most frequent are bacterial or viral gastroenteritis. Today, thermal treatments are the most often used for spice decontamination but they present some important disadvantages such as the loss of organoleptic properties. Pulsed light (PL) treatment has emerged in recent years as a feasible alternative to thermal treatment for killing pathogenic and spoilage microorganisms. In our study, the main objective was to assess the decontamination of spices by pulsed light. Experiments were carried out first on glass marbles in order to mimic spice grains and then on artificially contaminated black peppercorns. Samples were inoculated with a known concentration of Bacillus subtilis spores and then exposed to 2, 4, 6, 8 and 10 flashes of light. Experimental results confirmed that for both glass marbles and peppercorns, PL leads to a decrease in the microbial level. Indeed, a PL treatment superior to 6 pulses applied to glass marbles produced a 2.7 log reduction of B. subtilis spores. These results show a promising future for the use of PL for the reduction of microbial contamination in spices.