It is clear that for HWB blanching, penetrating of heat in the
stem lettuce tissues takes longer time, so the cell walls can be
greatly damaged causing larger amount of nutrients (ions) loss
due to leaching (Table 2). Ions in the polar/reactive sites of high
polymer molecules or the ones forming bridges in the stem lettuces
can also be leached off (Owen and Fennema, 1996; Karp,
1999). However, with MWB this is not the case because internal
heat generation can easily penetrate in the vegetable tissues (Ramesh
et al., 2002; Lin and Brewer, 2005). So, the electrical conductivity
of HWB samples was higher than that of NOB samples
because only few ions remained in the samples after blanching.