Figure 4.

TEER of Caco-2 cells cultured with OA + NIC. Data in the graph are represented as percentage over the initial TEER value and given as means (n = 6) ± SEM, represented by vertical bars. Means with different letters indicate statistical significance with p < 0.05 (a, b); means with at least one common letter are not significantly different (ab), colors of the letters refer to the different treatments. TEER = transepithelial electrical resistance (Ω·cm²); CTR = control group; OA + NIC 200 = treated group with 200 ppm of OA + NIC, composed from 260 µM of citric acid, 298 µM of sorbic acid, 23 µM of thymol, and 13 µM of vanillin; OA + NIC 1000 = treated group with 1000 ppm of OA + NIC, composed from 1300 µM of citric acid, 1490 µM of sorbic acid, 110 µM of thymol, and 70 µM of vanillin.