To utilize textured vegetable protein (TVP) in food manufacturing, TVP was soaked in salt solutions of different concentrations. Physicochemical quality characteristics of TVP were then measured. When TVP was soaked in a salt solution, the pH tended to increase compared to the control. However, the pH decreased after 18 hours of soaking. The salinity of the control decreased slightly from the initial value depending on the soaking time. The group treated with salt solution showed higher salinity than the control. Water absorption capacity of the control increased as the soaking time increased. However, water absorption capacity of the group treated with salt solution decreased as the concentration of salt solution increased. Lightness of the group treated with salt solution showed less change than the control during soaking. The redness increased as the concentration of salt solution increased. The yellowness increased compared to the control during soaking. Hardness, gumminess, and chewiness of the control decreased during soaking in water. The group treated with salt solution showed significantly higher hardness, gumminess, and chewiness as the concentration of the salt solution increased. However, adhesiveness, elasticity, and cohesiveness generally did not show significant differences among samples.
Differences in sugar and salt penetrarion rates of radish depending on size and concentration of solution were examined. 2x2x2 and 4x4x4 cm cube-shaped radish examined in different pickling condition (salt 2, 4, 6, 8% and sugar 5, 10, 15, 20% brix). After 12hr storage, Salt penetration rate of radish cut into 2x2x2 cm was faster than that of 4x4x4 cm in all salt solution. Size dependent sugar penetration showed same tendency with size dependent salt penetration. Also, increase in salt and sugar concentration led to increase in salt and sugar permeation rate.
A possibility of the implementation of a quartz crystal sensor to the determination of chemical oxygen demand is examined by checking the electrochemical behavior of the sensor in a glucose solution. Since the surface of a quartz crystal has to be oxidized, a relatively active metal is coated on the surface of a usual 9 MHz AT-cut crystal. The electrochemical behavior is investigated by measuring the changes of current, resonant frequency and resonant resistance while a constant potential is applied. The crystal is installed in a specially designed container, and a quartz crystal analyzer is utilized to measure the frequency and resistance simultaneously. The variations of the measurements are examined at different concentrations of glucose solution, and a proper relation between the concentrations of glucose solution, and a proper relation between the concentration and the measurements is analyzed. As a result, it is found that a linear relation between the concentration of less than 900 ppm and the peak current when a constant potential of -180 mV (SSCE) is applied. The relation can be utilized for the determination of glucose concentration in sea water, and considering a direct relation between gluose concentration and chemical oxygen demand tells a possibility of the measurement of chemical oxygen demand using quartz crystal oscillators.