• Applied Chemistry for Engineering
• /
• v.8 no.6
• /
• pp.893-900
• /
• 1997

In this study, vapor-liquid equilibria of a binary system, which consists of glycerol and water, are measured using a vaporrecirculating modified Othmer still at various subatmospheric pressures. The constituent components of the binary system considered in this study exhibit a large difference in the boiling temperatures. Since it is generally observed that the properties of a mixture greatly differ from those of the pure components, the phase equilibrium characteristics of a mixture can not be predicted from the properties of the pure components. Furthermore, an abrupt increase in the boiling temperature occurs as the concentration of the higher boiling component exceeds a certain value. Therefore, it is essential to acquire realistic phase equilibrium data of the mixture for industrial applications. Using the UNIQUAC model, the experimental vapor-liquid equilibrium data are correlated with good accuracy. The thermodynamic consistency test is also performed to ensure soundness of the data.

• Applied Chemistry for Engineering
• /
• v.21 no.3
• /
• pp.295-300
• /
• 2010

A binary system of 1-propanol and bromochloromethane which exhibits an azeotropic point and a considerable nonideal phase behavior probably due to the large boiling point difference is not amenable in the actual chemical processes such as the distillation tower and absorber. Therefore, experimental data of phase behavior data of this mixture are indispensable in understanding the inherent thermodynamic characteristics for an efficient application of the system in the industrial processes. In this work, the isobaric vapor-liquid equilibrium of a binary mixture consisting of 1-propanol and bromochloromethane was measured by using a recirculating equilibrium cell at various pressures ranging from 30 to 70 kPa. The measured VLE data were correlated in a satisfactory manner by using the UNIQUAC and NRTL models along with the thermodynamic consistency test based on Gibbs/Duhem equation. In addition, the excess molar volume of the mixture was also measured by using a vibrating densitometer and correlated with a Redlich-Kister polynomial.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.13 no.1
• /
• pp.64-70
• /
• 1984

In this experiment, the changes in the components of carbohydrate and their enzyme activities were investigated to study the conversion of sugars in tomato under sub-atmospheric pressure storage .The results obtained are as follows: The soluble sugars in tomato fruits were, for the most part, fructose and glucose together with small quantity of sucrose and maltose. The content of fructose increased throughout the storage, while that of glucose increased at an early stage but decreased at the latter part, and that of sucrose decreased drastically with progress of storage. The activity of ${\alpha}-amylase$ and invertase playing important roles in conversion of sugars showed a rapid increase at onset of respiration climacteric, resulting that the content of total soluble sugar showed a tendency to decrease strikingly, whereas those of starch and sucrose to decrease rapidly. Thus, the effect of temperature was more pronounced than that of pressure.

• Korean Chemical Engineering Research
• /
• v.56 no.2
• /
• pp.222-228
• /
• 2018

Benzene is one of the most widely used basic materials in the petrochemical industry. Generally, benzene exists as a mixture with alcohols rather than as a pure substance. Further, the alcohols-added mixtures usually exhibit an azeotropic composition. In this context, knowledge of the phase equilibrium behavior of the mixture is essential for its separation and purification. In this study, the vapor-liquid equilibrium data were measured in favor of a recirculating VLE apparatus under constant pressure for the 1 - propanol / benzene system. The measured vapor - liquid equilibrium data were also correlated by using the UNIQUAC and WILSON models and the thermodynamic consistency test based on the Gibbs/Duhem equation was followed. The results of the phase equilibrium experiment revealed RMSEs (Root Mean Square Error) and AADs (Average Absolute Deviation) of less than 0.05 for both models, indicating a good agreement between the experimental value and the calculated value. The results of the thermodynamic consistency test also confirmed through the residual term within ${\pm}0.2$.

• Korean Journal of Food Science and Technology
• /
• v.20 no.1
• /
• pp.63-71
• /
• 1988

Total lipid contents of tomato fruits were 97.6mg% and composed of neutral lipid(45.1mg%), phospholipid(31.2mg%) and glycolipid(12.4mg%). The contents of neutral lipid were slowly increased from the period of climacteric rise, but those of glycolipid and phospholipid were slowly decreased at the end of storage period. Major fatty acids in all lipids were identified to be palmitic, stearic, linoleic and oleic acids. The contents of linoleic acid in all lipids at $25^{\circ}C$ and those in neutrallipid at $15^{\circ}C$ were decreased, while those in phospholipid were slightly increased during storage. The contents of palmitic acid in neutral lipid were decreased, whereas those in glycolipid and phospholipid have a tendency to increase during storage. As for normal atmospheric pressure-normal temperature(NAP-N) condition, volatiles from homogenated tomato fruits were positively correlated with palmitic acid of neutral lipid, whereas negatively correlated with linoleic acid. As for subatmospheric pressure-low temperature(SAP-L) condition, the relationship between volatiles and fatty acids of neutral lipid was similar to NAP-N condition. Volatiles were positively correlated with linoleic acid of glycolipid and stearic acid of phosholipid, whereas negatively correlated with oleic acid of glycolipid and palmitic acid of phospholipid, respectively.

• Current Research on Agriculture and Life Sciences
• /
• v.3
• /
• pp.92-98
• /
• 1985

The experiments were conducted to investigate the activity changes of peroxidase, existence of isoenzyme and the changes of reserved substances in tomato under subatmospheric pressure storage condition. The results obtained were as follows: 1. Soluble fraction showed the highest peroxidase activity and followed by cell wall fraction, mitochondria fraction and ribosome fraction in that order. 2. Peroxidase activity was decreased during the ripening and senescence period in tomato. Especially, peroxidase activity in tomato was higher at a room temperature ($25^{\circ}C$) than at a low temperature ($15^{\circ}C$). The decreasing inclination was similar in both treatment. The peroxidase activity was higher in 380 Torr, than in 570 Torr. 3. At least, two isoperoxidases(Soluble or solubilized) were identified from different extraction procedures. Three of four isoenzymes were recognized from a vertical slab of polyacrylamide gel electrophoresis. 4. The changes of components in tomato under SAP were generally affected by temperature and pressure. Especially, quality of tomato stored at a low temperature ($15^{\circ}C$) and SAP (380 Torr.) was best during storage.