Application of Pulsed Light to Sliced Cheese: Effect on Listeria Inactivation, Sensory Quality and Volatile Profile

Two cheese varieties with different surface features (Gouda and Manchego) were tested for pulsed light decontamination of Listeria sp. on ready-to-eat presentations. Sensory quality and volatile profile were also studied. Cheese slices were flashed with fluences comprised between 0.9 and 8.4 J/cm 2 . The treatment was less effective in Manchego than in Gouda, in which 3 log cfu/cm 2 were obtained with 0.9 J/cm 2 . No sensory changes were observed due to the application of this dose. In Manchego slices, the maximum inactivation obtained was lower than 1 log cfu/cm 2 even at the highest fluence used. In both cheeses, differences in odour and flavour were reported immediately after treatment for fluences ≥4.2 J/cm 2 , due to the development of sulfur notes. Volatile analysis showed an increase of sulfur compounds which could explain these observations. The concentration of sulfur volatiles and the corresponding sensory notes disappeared during cold storage. In view of these results, pulsed light could be considered a useful strategy to decontaminate smooth-surface ready-to-eat cheeses.