Effect of active packaging based on polyethylene/propylene films containing thymol on the quality attributes and shelf life of season salad

Vegetables have a short shelf life, and because they are eaten fresh, it is necessary to use healthy and natural methods to increase their shelf life. The present study has investigated the effect of active packaging containing the active ingredient of thymol on the color and pH measurements, microbial evaluation, total mold and yeast count, and the sensory properties of seasonal salad during six-day storage refrigerator temperature. For this purpose, seasonal salads were packed with oriented polypropylene (OPP) and low-density polyethylene (LDPE) films immersed in thymol essential oil for 1, 2, and 3 days. Results show that season salads packed with OPP and LDPE films immersed in thymol essential oil for three days had higher pH and lower mold and yeast count than control and other treatments. The mold and yeast count were significantly lower (p < 0.05) in a sample packed with OPP films containing essential oil compared to the LDPE/ thymol essential oil. The L* and a*values decreased during storage time. The L* and -a * indices of season salads were lower in OPP and LDPE films immersed in thymol essential oil for three days than the neat and other groups. Sensory evaluation showed that immersion in thymol essential oil improved sensory attributes (p <0.05).  The coated films, especially OPP, improved the color, reduced the number of mold and yeast, increased the shelf life, and improved the sensory attributes of seasonal salads. Therefore, films treated with thymol essential oil can act as active packaging.