Effects of different coating formulations on the quality and shelf life of lettuce ( Lactuca sativa L.)

Post-harvest losses in leafy vegetables such as lettuce (Lactuca sativa L. cv. Grise Maraichere) are a critical issue due to physiological weight loss, microbial spoilage, and biochemical deterioration. In this study, the effects of four different coating formulations [Chitosan Microparticles (CsMPs); CsMPs+thyme essential oil (CsMPs+Oil); CsMPs+Selenium Microparticles (CsMPs+SeMPs); CsMPs+SeMPs+thyme oil (CsMPs+SeMPs+Oil)] on post-harvest quality parameters in lettuce. Plants were harvested at optimal maturity stage (65 days), coated using the dip method, and stored for 10 days at two different temperatures [4°C (95 ± 2% humidity) and 21°C (60 ± 2% humidity)]. At the end of the 10-day storage period, the CsMPs+SeMPs application at 4°C reduced weight loss from 11.59% to 6.42% compared to the control (p < .05). At the same temperature, the decay rate was 4.50% in the control group, while it decreased to 0% in the CsMPs+SeMPs and CsMPs+SeMPs+Oil applications. In terms of color stability, the highest chroma value at 4°C was obtained with the CsMPs+SeMPs application (40.52), while CsMPs+SeMPs+Oil showed the best performance at 21°C (35.17). Respiration rate was reduced to 27.4% at 4°C with the CsMPs+SeMPs application (control: 33.9%); at 21°C, the same application suppressed metabolic activity from 115.3% to 91.7%. The findings indicate that CsMPs+SeMPs and CsMPs+SeMPs+Oil formulations are particularly effective in reducing post-harvest quality losses in lettuce. It is recommended that these coating formulations be tested on other leafy vegetables (parsley, arugula, spinach, cabbage) with different surface morphologies and storage requirements.