Synergistic Effects of Epigallocatechin Gallate-Ascorbic Acid and Inert-Gas Modified Atmosphere Packaging on Color Restoration in Pre-Discolored Longtail Tuna Slices

Color is a primary attribute determining consumer acceptance of premium-quality tuna. Discoloration is commonly considered as the loss of freshness and eating quality, leading to food waste. This study investigated color and quality changes in longtail tuna slices during 48 h of simulated retail display and evaluated the efficacy of epigallocatechin gallate–ascorbic acid (EA) combined with nitrogen- or argon-rich modified atmosphere packaging (NO or AO) in restoring pre-discolored tuna slices (2DS) during 4 days of refrigerated storage. The simulated retail display caused a quick loss of redness (a* value and a*/b*), an increase in metmyoglobin, and enhanced oxidation of lipids and proteins, which made the visual quality undesirable. 2DS-EA/AO profoundly restored the redness, reduced metmyoglobin, and suppressed oxidative degradation. Partial recovery and short-term color stabilization were achieved through the combined treatments, which extended acceptability up to three days. Therefore, a synergistic polyphenol-reducing agent-modified atmosphere packaging (MAP) approach could be used to restore discolored sashimi-grade tuna and decrease tuna waste associated with undesirable discoloration.