Sliced fermented salami sausages packaged in modified atmospheres (MA) are prone to discoloration by a combination of residual O₂ in the headspace and light at retail display. To avoid discoloration, packages of uncooked salami should be stored in darkness until all O₂ is removed by internal processes in the product, usually within a few days. The aim of this study was to determine if the color of salami could return from brown to red by extended illuminated display in packages with MA`s, in which residual O₂ was present in the early, but not the later stage of display.

Dry fermented raw salami was produced with pork, pork fat, beef, starter culture, salt, sugars and 120 ppm sodium nitrite. Packages with 150 g sliced salami were inserted with air and CO₂ through self-sealing septas to contain approximately 5% O₂, 50% CO₂ and 45% N₂ with a gas to product ratio of 1.1 to 1. The lower and upper films for the packages were laminates with EVOH as O₂ barrier. The transparent packages were exposed to continuous LED light type 68 W 830 (Glamox AS, Oslo, Norway) of 3.5 W/m² (1100 lux) for 10 d at 20°C. Concentrations of O₂ in the packages were measured at the time of packaging and d 1, 2, 3, and 4 of display with a Checkmate 3 instrument (Dansensor, Ringsted, Denmark). CIE L*a*b* values (lightness, redness and yellowness) were analyzed through the packaging films at d 0, 1, 2, 3, 4, 7, and 10 of display with a Minolta Chroma Meter CR-400 (Konica Minolta Inc., Tokyo, Japan). The experiment included 3 batches of salami with 5 packages per batch. Analysis of variance was performed for all data using a general linear model in Minitab 17 Statistical Software (Minitab Inc., State College, PA, USA), and means were separated by Tukey’s multiple comparison test.

Concentrations of O₂ were reduced from the initial 5% to 0% at d 4 of display. The initial a* values of sausages from the 3 batches were approximately 16, which is fully red. Within 2 d of display, a* values were substantially reduced to 9 to 10 (P < 0.05), with a distinct browning or discoloration. By end of display at d 10, a* values were slightly higher at 10 to 11 (P < 0.05), but sausages were still clearly discolored. L* and b* values were not affected by residual O₂ and light display (P > 0.05). Packages from 1 of the 3 batches had higher O₂ concentrations at d 2 and 3, consistent with slightly lower a* values of the sausages at the middle and late period of display than the other 2 batches (P < 0.05).

Illuminated display of salami slices in MA`s with initial high residual O₂ resulted in a non-reversible discoloration of the product, despite that it was kept under anaerobic conditions for the middle and late display. A subsequent and minimal increase in a* value at this time of display would not be noticed by consumers.