The combined impact of calcium lactate with cysteine pretreatment and perforation‐mediated modified atmosphere packaging on quality preservation of fresh‐cut ‘Romaine’ lettuce

Abstract

The effect of perforation‐mediated modified atmosphere packaging (PM‐MAP) in combination with calcium lactate (1.5% CaL) and cysteine (0.1, 0.5% Cys) immersion pretreatments on the quality preservation of fresh‐cut ‘Romaine’ lettuce was assessed for 12 days, at 5 and 10 °C. The shredded lettuce was packed in low‐density polyethylene films (LDPE, 62 µm thickness), including different perforation numbers of 0 (N‐MAP), 20 (20‐PM‐MAP, Diameter = 64 µm), and 40 (40‐PM‐MAP, Diameter = 64µm) per in square meter. Indices of quality maintenance were investigated. The total microbial counts were below the specified limits for ready‐to‐eat vegetables (< 6 log CFU/g) considering both pretreated 20‐PM‐MAP and N‐MAP samples on day 12. After 8 days, a significant difference (P < 0.05) was observed in the browning index (BI), the total color difference (ΔE), and the chlorophyll content between N‐MAP and 20‐PM‐MAP samples with better results in 20‐PM‐MA packages. At 10 °C, the BI in pretreated 20‐PM‐MAP samples was 32.44% to 58.35% less than N‐MAP samples, on the last day of storage. The 20‐PM‐MAP samples pretreated with 1.5% CaL/0.5% Cys had the highest (P < 0.05) crispness coefficient and water content values. It seems that packaging the pretreated lettuce in 20‐PM‐MA packages is more effective for maintaining the visual properties (green fresh appearance) of this product, from the 8th to the 12th day of storage. Practical Application The medium to high respiration rate of fresh‐cut lettuce causes O₂ level drops below its tolerance limit (<1% to 3%) inside the modified atmosphere packaging (MAP). It results in severe browning, off‐odors, off‐flavor, and growth of anaerobiosis. Perforated‐mediated modified atmosphere packaging (PM‐MAP) technology can be introduced as an alternative to a nonperforated MAP system (conventional MAP) for fresh‐cut lettuce. The application of the PM‐MAP system in combination with calcium lactate and cysteine immersion pretreatment (CaL/Cys) may lead to better maintenance of the physicochemical properties of this product.