UVB and UVC light-emitting diode effects on pectin methyl esterase activity, antioxidant capacity and bioactive compounds in tomato juice

Tomatoes are widely processed into products such as pastes, sauces, and juices. These products undergo thermal treatments during their formulation, such as Cold Break (CB: 60-67 degrees C) or Hot Break (HB: 93-99 degrees C) to ensure microbiological and enzymatic stability. This study compares the effect of thermal treatments (CB and HB) with UV-LED light (UVB and UVC) on Pectin Methylesterase (PME) activity, antioxidant capacity, and bioactive compounds of tomato juice. Samples were treated with delivered doses of UVB LED (46, 69, 92 mJ/cm(2)) and UVC LED (167, 250, 333 mJ/cm(2)) in a static regime, using 275 and 310 nm diodes. There was no significant difference in the reduction of PME activity between UVB-LED treatment at 92 mJ/cm(2) and HB because delivered values of 38.5 f 3.3 % and 45.3 f 2.4 %, respectively. In addition, UVC-LED presented the lowest PME activity with a value of 8.1 f 1.9 %. UVB-LED and CB showed no significant differences in total phenolic content (mg GAE/L), total flavonoids (mg/QE/L) and antioxidant capacity (mmol TE/L), respectively (p > 0.05). UV-LED technology shows potential for enzyme inactivation in tomato juice; that is, it could potentially lead to the development of similar food matrixes. However, future research should explore other processing conditions.