Besides, the structure of a tomato is disrupted during
drying, and this may also cause the liberation of peroxidative and
hydrolytic enzymes (Toor & Savage, 2006). In addition, other reasons
for the loss of phenolic content could have been the binding
of phenols to proteins, changes in chemical structures, or impossibility
of extraction by presently available methods (Martin-
Cabrejas et al., 2009; Miranda et al., 2010). However, Lavelli,
Hippeli, Peri, and Elstner (1999) observed an increase in the phenolic
content in tomatoes dried at 80 C for 7 h. Investigators
explained that this was due to rehydration, along with the release
of phenols from the cell walls and an increase in free hydroxyphenols.
Dewanto, Wu, Adom, and Liu (2002) reported that high temperature
applications, such as 88 C, to tomatoes did not affect
their phenolic content. The same group indicated that the thermal
process at 88 C deactivated oxidative and hydrolytic enzymes that
may cause the loss of phenolic acids. Chan et al. (2009) reported
that there was a decrease in TPC when leaves of ginger were dried
by the sun, in an oven, and by microwaves. The same group found
an increase in phenolic content in ginger leaves that had been
freeze dried. However, results were not calculated on the basis of
dried samples.