Agriculture Reference
In-Depth Information
concentration is similar to the influences presented in the case when sucrose solutions were
used. The difference compared to the previous discussion is in magnitude of effect as result of
the salt presence which results in increased osmotic pressure.
The effects of sucrose and sodium chloride concentration on the WL initial rate are given
in Figure 5. At low concentrations of both solutes water loss initial rate is slowed down by
increasing concentrations of single solute. In absence of sodium chloride the water loss initial
rate was not significantly influenced by increasing sucrose concentration. This behavior can
be explained by the enhancement of the solution viscosity. On the other hand, at low sucrose
concentrations increase of salt concentration led to the slight decrease of initial water loss
rate, compared to the sharp decrease at higher values of sucrose concentration. At the early
stages of osmotic dehydration process sodium chloride molecules cannot penetrate deep
inside the cossettes tissue in order to increase the water loss from the deeper layers, that fact
is especially pronounced by more viscose high sucrose concentrations.
Figure 5. Effects of sucrose and sodium chloride concentration on water loss initial rate.
At equilibrium completely different behavior can be observed (Figure 6). The increasing
of sucrose concentration led to increase in values of water loss at equilibrium; the same
conclusion is valid for the increase of salt concentration. At low sucrose concentration
influence of salt concentration is more pronounced, compared to higher concentration around
60% w/w. At cellular level, the influence of adding salt into osmotic solution can be
explained by the difference in molecular dimensions of solutes. Both sucrose and sodium
chloride can pass through the cellular membrane of the sugar beet tissue, while only small salt
ions (NaCl) can diffuse through cytoplasmic membrane (Isse and Schubert, 1992). Limited
diffusion of sucrose is the reason for molecules to accumulate at the surface of the cytoplasm
