Effect of Composition of The Soaking Solution and Its Osmotic Pressure on Permeation of NaCl and Sugar and on the Moisture Content of Cucumber Flesh

Abstract

Round slices of cucumber were soaked in nine kinds of aqueous solution composed of a fixed concentration of either 2.5,5.0, or 10.0% NaCl and various concentrations of sorbitol between 10.0and 40.0%. These aqueous solutions covered a wider range of NaCl concentration than those previously examined. The permeation of sorbitol and NaCl into the flesh, as well as the moisture content(%) of the flesh were investigated with the progress of soaking time at 4°C.
The permeation of NaCl into the flesh increased with increasing NaCl concentration in the soaking solution and was unaffected by the coexistence of sorbitol, whereas the permeation of sorbitol increased with increasing sorbitol concentration, but was slightly affected by the coexistence of NaCl. NaCl and sorbitol permeated into the flesh while maintaining a uniform weight ratio throughout the soaking process. The ratio of NaCl and sorbitol was largely dependent on the composition of the soaking solution.
The NaCl or sorbitol concentration in the cucumber flesh increased proportionally with increasing partial osmotic pressure of NaCl or sorbitol in the soaking solution, although the rate of increase for sorbitol was relatively less with the higher ranges of partial osmotic pressure provided by sorbitol. There was a strong negative correlation between the concentration of permeated NaCl or sorbitol and the moisture content of the flesh. The relationship varied somewhat according to the composition of the soaking solution.
There was a strong positive correlation between the rate of reduction of the moisture content of the flesh and the combined osmotic pressure for all the soaking solutions examined. These results provide useful data for practical control of the quality of soaked cucumber products.