• Korean Journal of Food Science and Technology
• /
• 제47권4호
• /
• pp.539-543
• /
• 2015

A hardy kiwifruit is a good source of phenolics and antioxidants. This study was aimed at investigating the effects of hot air drying at three different temperatures (35, 50, and $70^{\circ}C$) for 24 h on the total phenolic and flavonoid contents and the antioxidant capacity of hardy kiwifruits of Actinidia arguta ${\times}$ A. deliciosa cv. Mansoo. Dried kiwifruit extracts were produced using 80% (v/v) aqueous ethanol under homogenization. Hot air drying lowered the total phenolic and flavonoid contents and decreased the antioxidant capacity in the dried kiwifruits compared with their fresh counterparts. The results also revealed high positive linear correlations of antioxidant capacity with total phenolic and flavonoid contents, indicating that phenolics are the major contributors to antioxidant capacity. Our results suggested that an optimal drying process must be determined for industrial application in order to obtain dried kiwifruits with increased antioxidant capacity for consumers.

• Korean Journal of Food Science and Technology
• /
• 제32권3호
• /
• pp.598-603
• /
• 2000

This study was conducted to enhance the storage stability and the wholesomeness of salted and fermented shrimp manufactured with different salt levels by high hydrostatic pressure sterilization. The effects of high hydrostatic pressure treatment on the putrefactive bacteria in the fermented shrimps were investigated and the sterilization kinetics was analyzed. The initial microbial counts of the fermented shrimp with 8%, 18% salt aged for 6 weeks at $20^{circ}C$ were $1.6{\times}10^3,\;1.4{\times}10^4$ CFU/g for bacteria grown on Vibrio selective media, $9.3{\times}10^3,\;1.7{\times}10^5$ CFU/g for bacteria grown on Staphylococcus selective media, respectively, and null for bacteria grown on Salmonella selective media. The degree of the sterilization increased with the magnitude of the pressure and the treatment time. The fermented shrimp pressurized at 6,500 atm for 10 min had no detectable bacteria grown on Vibrio and Staphylococcus selective media at $10^2$ CFU/g detecting limit. High hydrostatic pressure sterilization could be analyzed by first order reaction kinetics. The $D_P$ values of the bacteria grown on Vibrio selective media of the fermented shrimp at 18% salt were higher than those at 8% salt, while those of the bacteria grown on Staphylococcus selective media showed an inverse trend. The $z_p$ values of 8% salt fermented shrimp were higher than those of 18% salt for both bacteria grown on Vibrio selective media and Staphylococcus selective media. High hydrostatic pressure treatment could be applied for the sterilization of the fermented shrimp, and the optimum high pressure sterilization condition was 10 min treatment at 6,500 atm.

• Korean Chemical Engineering Research
• /
• 제53권2호
• /
• pp.150-155
• /
• 2015

Recently, LNG receiving terminals have been widely constructed and expanded for an increase in LNG demand. Selection of the storage tank for send-out and estimation of send-out flow rate have significant influence to process operation and economics. In this study, a send-out flow rate of each storage tank is optimized in order to minimize the total BOG generation rate. Considering a size and characteristic of each storage tanks, BOG flow rates are estimated using a dynamic simulation with varying liquid levels in the tanks. The regression model is developed fitting BOG flow rates and tank liquid levels, which are boil off rate model to predict BOG flow rates with particular level data. The objective function and constraints including required total send-out flow rate and level limit in the tanks are formulated to optimize a send-out flow rate of each tank. This method for optimization of send-out operation is applied to the Incheon LNG receiving terminal considering two scenarios for various liquid levels and maximum and minimum required send-out flow rates. For maximum required send-out flow rate, this method achieves BOG reduction of 9% comparing with assumed conventional operation.

• Food Science and Preservation
• /
• 제9권2호
• /
• pp.212-220
• /
• 2002

Spray drying was used a means for microencapsulation of Aster scaber and Aster glehni. The optimum conditions of spray drying were found to be 210$^{\circ}C$ for the inlet temperature and 5 $m\ell$/min for the feeding rate. The color difference decreased by 12∼25 % far the herb extracts depending on storage temperatures. With an increase in storage temperature, color of the control changed considerably compared to microencapsulated powders. This is due to the fact that wall materials minimized effect of oxygen on the herb extracts. Microencapsulated powders in the amounts of 50 ppm and 250 ppm added to hydrogenated soybean oils led to lower acid values and conjugated diene values during 6 day storage. Compared to the control, the herb extracts displayed 16∼48% increase in antioxidation effect, while the microencapsulated powders exhibited 46∼88% increase. Extracts also showed lower conjugated dienoic acid contents than those of the control. Although antioxidation effect of the microencapsulated powders did not prevail on the significant level in the early stage of storage of oils tested, it became predominant after one week of storage as wall materials were gradually degraded under the high temperature thereby releasing core material from the microcapsule.

• Journal of the Mineralogical Society of Korea
• /
• 제23권3호
• /
• pp.235-242
• /
• 2010

Froth flotation using the residual water in the end of flotation process has been performed through controlling of pH. IEP (isoelectric point) of molybdenite and quartz in distilled water was below pH 3 and pH 2.7, respectively and the stabilized range was pH 5~10. In case of a suspension in reusing water, zeta potential of molybdenite decreased to below -10 mV or less at over pH 4 due to residual flocculants. As result of pH control, flotation efficiency in the alkaline conditions was deteriorated by flocculation, resulting from expanded polymer chain, ion bridge of the divalent metal cations ($Ca^{2+}$), and hydrophobic interactions between the nonpolar site of polymer/the hydrophobic areas of the particle surfaces. However, the weak acid conditions (pH 5.5~6) improved the efficiency of flotation as hydrogen ions neutralize polymer chains and then weakened its function. In cleans after rougher flotation, the Mo grade of 52.7% and recovery of 90.1% could be successfully obtained under the conditions of 20 g/t kerosene, 50 g/t AF65, 300 g/t $Na_2SiO_3$, pH 5.5 and 2 cleaning times. Hence, we developed a technique which can continuously supply waste water filtered from tailings into the grinding-rougher-cleaning processes.

• Journal of the Korean Applied Science and Technology
• /
• 제33권4호
• /
• pp.676-685
• /
• 2016

This study investigated the conversion of oil products from polystyrene by using dispersed Co and Mo catalyst on reaction time and concentration change for knowledging on characteristics at low temperature (425, 450 and $475^{\circ}C$) pyrolysis and reaction time(20~80 min, 15 min interval) in a batch reactor. It will be showed the conditions for optimum pyrolysis at reaction temperature $450^{\circ}C$ and the reaction time 35min, and the main components of the converted liquid oil were styrene and benzene derivatives by GC/MS. The oil products formed during pyrolysis were classified into gas, gasoline, kero, diesel and heavy oil according to the domestic specification of petroleum products. The pyrolysis conversion rate was showed as Co catalyst > Mo catalyst > Thermal in all reaction time at reaction temperature $450^{\circ}C$. The yields rate of gas, kerosine, diesel were the most hight at Mo Catalyst, gasoline was at thermal and heavy oil was at Co catalyst. The conversion rate and yields of the pyrolysis products were the most height when Co catalyst ratio was 100%.

• Journal of the Korean Society of Food Science and Nutrition
• /
• 제28권4호
• /
• pp.876-881
• /
• 1999

Fresh onions were extracted by two methods of conventional extraction(CE) and microwave assisted extraction(MAE) under different extraction conditions. Onion extracts obtained by CE and MAE were examined in oleoresin yield and physiological activities. The optimal extraction time of MAE was about 5 minutes, whereas that of CE was 2 hours. Therefore extraction time was shortened drastically by MAE but there was no significance in oleolesin yield. The electron donating abilities also showed negligible difference between two extracts obtained by CE and MAE, and 45% level in CE and 50% level in MAE. The nitrite scavenging effect was diminished while pH was increasing, and showed a high elimination effect over 85% at pH 1.2. The tyrosinase inhibitory effect was 20% level in both CE and MAE when water was used and 40% level when ethyl alcohol was used. The angiotensin I converting enzyme inhibitory effect showed higher activity with 70% level in MAE than 60% level in CE. The pyruvic acid content was 6.8 and 6.4 moles per 1g of fresh onion by CE and MAE when water was used, and was 4.3 and 5.6 moles by CE and MAE when ethyl alcohol was used.

• Korean Chemical Engineering Research
• /
• 제50권2호
• /
• pp.238-243
• /
• 2012

Laminaria roots have not been practically used in Korea. In this study, the extraction process of carbohydrates and minerals from Laminaria roots was investigated and the properties of extracted components were measured. Hydrochloric acid generally used in carbohydrate extraction from seaweeds in order to obtain high extraction yield. But in this work, to utilize extracted components as a functional food material, organic acids such as citric acid were used. Organic acid as extraction solvent has low extraction yield compared to strong acids. Therefore optimum condition for maximum yield was investigated in carbohydrate extraction from Laminaria roots using organic acid. We measured the extraction yields of carbohydrate with variation of extraction temperature, extraction time, concentration of organic acid and particle size of samples. The extraction yield increased as the particle size decreased and temperature became high. The extraction yield was 19.0 wt% after 4.0 hours extraction with 0.2 wt% citric acid at $100^{\circ}C$. Potassium concentration was high compared other minerals in extraction solution, that is, the ratio of K/Na was about 3.0. Fucoidan from Laminaria roots had same carbohydrate composition and lower molecular weight compared that of Undaria pinnatifida.

• Korean Chemical Engineering Research
• /
• 제55권2호
• /
• pp.201-213
• /
• 2017

Water is removed from crude oil containing water by using oil separator. This study aims to develop a three-dimensional (3D) Eulerian computational fluid dynamics (CFD) model to predict the separation efficiency of air-water-oil separator. In the incompressible, isothermal and unsteady-state CFD model, air is defined as continuous phase, and water and oil are given as dispersed phase. The momentum equation includes the drag force, lift force and resistance force of porous media. The standard k-${\varepsilon}$ model is used for turbulence flow. The exit pressures of water and oil play an important role in determining the liquid level of the oil separator. The exit pressures were identified to be 6.3 kPa and 5.1 kPa for water and oil, respectively, to keep a liquid level of 25 cm at a normal operating condition. The time evolution of volume fractions of air, water and oil was investigated. The settling velocities of water and oil along the longitudinal separator distance were analyzed, when the oil separator reached a steady-state. The oil separation efficiency obtained from the CFD model was 99.85%, which agreed well with experimental data. The relatively simple CFD model can be used for the modification of oil separator structure and finding optimal operating conditions.

• KSBB Journal
• /
• 제17권1호
• /
• pp.93-99
• /
• 2002

Two-stage fed-batch culture of Candide tropicalis that was designated primarily to cultivate the cell in the glucose medium (1st stage) and then produced the xylitol from xylose medium (2nd stage) was developed to improve a xylitol yield and productivity. In the growth stage, glucose was automatically supplied to the fermentor by pH-stat mode when the pH was up 5.7, When a feeding medium was added in order to reach the glucose and yeast extract concentrations up to 100 and 40 g/L, respectively, a high cell concentration and a relatively low ethanol concentration were obtained in 18.5 h culture. In the production stage, initial xylose concentration of 150 g/L was the most favorable for obtaining the final xylitol concentration and productivity. The addition of mineral salts was also enhanced a xylitol production. But the aeration rate was not significantly affected a xylitol production. When the addition of 16 g yeast extract and 232.5 g xylose powder at the production stage was used, xylitol yield and productivity were significantly increased. With these conditions, xylitol concentration, yield and productivity of 108.9 g/L, 74%) and 3.3 g/L·h, respectively, were obtained in a final volume of 1.58 L. The further addition of 16 g yeast extract and 232.5 g xylose powder increased the working volume partly (1.67 L) and resulted in a relatively high xylitol concentration, yield and productivity of 193 g/L, 70% and 3.6 g/L·h, respectively.