A simple, easy-to-conduct student activity explored the antimicrobial property of spices and their use in food preservation. Samples of a typical Brazilian dessert were prepared with spices, under different conditions, and the appearance of microorganisms on the surface of the desserts was visually monitored as a function of time. The studied spices controlled the formation of microorganisms. This student activity had a strong visual impact on the students and encouraged them to repeat the experiment at home with other spices or seasonings.