This study purposed to determine the impacts of chitosan film (CF) (2%, w/v) coating combined with thyme oil (TO) (0.2%, 0.5%, 1%, (v/v)) on the quality properties of black olives during storage (3 months, +4 and 25°C). In the study, film properties (color, elongation at break, tensile strength, Young’s modulus, and scanning electron microscope (SEM)) were analyzed. In the second stage, table olive samples were assessed for physicochemical (% moisture, pH, titratable acidity, color (L*, a*, b* and ∆E*), and microbiological (yeast–mold and total viable count) properties. The average elongation at break, tensile strength, and Young’s modulus values of the obtained film coating samples were 70.02%, 16.66 MPa, 24.05 MPa for the CF; 74.69%, 14.79 MPa, 19.65 MPa for the CF + 0.2% TO; 77.21%, 10.79 MPa, 13.94 MPa for CF + 0.5% TO and 83.78%, 10.40 MPa, 12.69 MPa for CF + 1.0% TO group, respectively. Chitosan film sample was determined the highest tensile strength value and the CF+1% TO sample group was detected with the highest elongation at break. It was determined that the increase in the concentration of TO in the film increased the elongation at break and decreased the Young’s modulus value. Scanning electron microscope (SEM) surface images of group CF film have a homogeneous and uniform structure but added thyme oil occured a heterogeneous appearance. The L*, a*, b*, and ∆E* values increased with the addition of thyme oil and a statistically significant difference was found between samples (P < 0.05). The highest moisture loss was determined in the control (uncoated) group. The highest decrease in yeast–mold and total viable count value was found 4.89 log CFU/g CF + 0.2% TO and 5.21 log CFU/g in CF + 1.0% TO sample at the end of storage period at 4°C in table olives.

Edible film-coating technology is an innovative approach to help maintain food quality and inhibit microbial growth in place of synthetic preservatives. This study focused on evaluating the effects of chitosan (CS) films (2%) contained with thyme essential oil (TO) at 0.2, 0.5, and 1% on the microbiological changes, sensory, and quality attributes of green olives stored at 4 °C for 90 days. Table olive samples, which were covered with chitosan solutions containing different concentrations of thyme oil, were assessed for physicochemical (% moisture, pH, titratable acidity, color (L*, a*, b^*, and ΔE*)) and microbiological (total viable count and yeast and mold count) and sensory properties. During the storage period, moisture loss was more evident in the control group, decreasing to 53.62 ± 0.33% by day 90. In contrast, the CS and CS+TO coatings significantly reduced moisture loss. Specifically, the CS+0.2% TO, CS+0.5% TO, and CS+1% TO treatments maintained moisture levels around 57-58% at the end of storage. The overall sensory results indicated that edible coatings, particularly those containing thyme oil, effectively preserved the visual and textural quality of green olives throughout storage. However, high concentrations of thyme oil slightly reduced taste acceptability. Therefore, CS+0.2% TO and CS+0.5% TO formulations appear to offer the most balanced performance, combining effective antimicrobial protection with favorable sensory properties. The maximum reduction in total viable count (TVC) and yeast-mold was observed in the CS+1% TO group, with values of 4.36 and 3.07 log CFU/g, respectively. It has been determined that chitosan films containing thyme oil have an inhibitory effect on microbial activity. Overall, these results demonstrate the usability of edible films as synthetic preservatives and edible coating systems offer promising potential for preserving both the safety and quality of table olives, while also supporting consumer acceptance.