Retention of aroma compounds by lactic acid bacteria in model food media

The interactions between aroma compounds and other particles in foods, particularly with macromolecules, have been greatly studied in order to better understand the binding of flavors in food matrices. Bacteria possess many macromolecules on their cellular surface that provide them surface properties which are involved in the physicochemical interactions between cells and interfaces. However, the interactions between bacteria and aroma compounds have not received so much attention despite the presence of bacteria in many fermented products. In order to study the retention of aroma compounds by bacteria, we have investigated the retention of esters by lactic acid bacteria with static headspace techniques. Two strains of Lactococcus lactis subsp. lactis biov. diacetylactis reflecting the natural diversity of the bacterial surface properties and two ethyl esters generally involved in the cheese flavor (ethyl acetate and ethyl hexanoate) were chosen for the experiments. The results have shown that bacteria, through their surface physicochemical properties, can interact directly with aroma compounds or in an indirect way, by changing the emulsion characteristics. However, these effects depend on the physicochemical properties of both aroma compounds and bacterial surfaces.