The cut surface dipping in hot water temperature at 55 °C for 1, 2 and 3 minutes (446.67±2.38, 453.85±3.49 and 454.71±1.15 respectively) had phenolic compounds highest more than other treatments (Table 2). Because in 55 ° C was too high for iceberg lettuce and blanching may result leaves tissue was damage.
As a result, protein and fat were elements of cell denaturing and production of synthetic phenolic compounds increases (Borwornsak, 2002).