• Food Science and Preservation
• /
• v.23 no.2
• /
• pp.246-251
• /
• 2016

This study was performed to determine the effects of drying methods (HD, hot air drying; FD, freeze-drying) on the antioxidant and physiological abilities of Haw (Crataegus pinnatifida Bunge). Powder color values of dried Haw, L and b, were higher for HD, while the chroma values were higher for FD. The total polyphenol, and flavonoid contents of HD Haw and FD Haw were found to be $9.29{\pm}0.50mg\;GAE/mL$ and $15.48{\pm}0.38mg\;GAE/mL$, and $9.41{\pm}0.26mg\;RHE/mL$ and $26.46{\pm}0.34mg\;RHE/mL$, respectively. DPPH radical scavenging abilities at 100 mg/mL concentration were higher for FD (64.90%) than HD (28.66%), as were the reducing power, ABTS radical scavenging ability, and nitrite scavenging ability. However, the HMG-COA reductase of HD (74.67%) was higher than that of FD (72.10%). The ${\alpha}-glucosidase$ inhibitory abilities of HD and FD at a concentration of 0.1 mg/mL were 24.69% and 97.38%, respectively. These results indicate that Haw is a potential functional material and that freeze-drying Haw is better than hot air drying.

• The Bimonthly Magazine for Agrochemicals and Plant Protection
• /
• v.6 no.10
• /
• pp.47-56
• /
• 1985

• Journal of Energy Engineering
• /
• v.19 no.4
• /
• pp.228-233
• /
• 2010

About 55% of total energy is consumed in the industrial division. The industrial heat pump application will show magnificent energy saving effect as well as higher cost efficiency because of larger energy consuming volume of each facility and longer operation hour and higher stability against seasonal temperature change. Over 90% of dryer for industrial usage has hot wind heat source and hot wind dryer is the representative type covering 68.7% while its 30 ~ 50% lower heat efficiency causes lots of energy loss by exhaust air. Re-usage of exhaust air can improve energy efficiency of dryer because 68% heat energy or 78% of hot air lose in exhaust air. Therefore, high temperature heat pump dryer can be the best alternative. Comparing to the existing dryer with 30% ~ 50% energy efficiency, newly developing high temperature heat pump dryer will enhance energy efficiency up to 60% ~ 80% efficiency. In this paper, heat pump system for high temperature was designed, constructed and tested. The results have shown that system COPh is estimated as 3.3.

• Korean Journal of Food Science and Technology
• /
• v.18 no.6
• /
• pp.479-484
• /
• 1986

Two different types of solar collector for farm dryer- the flatplate type and the modified tubular type-were constructed and analyzed on their performances. The transparent plastic film, black painted galvanized iron sheet and black vinyl film were used for the cover and absorber of the flat-plate types. The simplified tubular type was constructed with transparent films for the cover and black vinyl films for the absorber Two elliptical iron rings were used to form a tubular shape through which air could pass. No remarkable differences were found in thermal efficiences between the absorbers made with galvanized iron sheet and black vinyl film. The average thermal efficiencies of the solar collectors were 42.8%(max.48.2%, min.38.2%) for flat plate type and 22.971 (max. 25.4%, min. 14.8%)) for tubular one. The empirical equations were proved to be applicable to the prediction of temperature elevation. The tubular solar heat collector was successfully applied to red peppers drying as a practical farm dryer. The drying rate was almost doubled compared to a conventional sun drying.

• Food Engineering Progress
• /
• v.21 no.1
• /
• pp.42-48
• /
• 2017

The purpose of this study was to verify the drying characteristics of steamed sweet potato and to establish optimal drying conditions for far-infrared drying of steamed sweet potato. 4 kg of steamed sweet potato was sliced to thicknesses of 8 and 10 mm, and dried by a far-infrared dryer until a final moisture content of $25{\pm}0.5%$. The far-infrared dryer conditions were an air velocity of 0.6, 0.8 m/s and drying temperature of 60, 70, and $80^{\circ}C$. The results can be summarized as follows. The drying time tended to be reduced as temperature and air velocity for drying increased. The Lewis and Modified Wang and Singh models were found to be suitable for drying of steamed sweet potato by a far-infrared dryer. The color difference was 35.09 on the following conditions: Thickness of 8 mm, temperature of $80^{\circ}C$, and air velocity of 0.8 m/s. The highest sugar content ($59.11^{\circ}Brix$) was observed on the conditions of a thickness of 8 mm, temperature of 80, and air velocity of 0.8 m/s. Energy consumption decreased on the conditions of higher temperature, slower air velocity, and thinner steamed sweet potato.

• Journal of Biosystems Engineering
• /
• v.6 no.2
• /
• pp.58-64
• /
• 1982

The fresh threshed paddy-mat dryings on the various environments were analyzed on their drying characteristics and rice quality resulted. The moisture content of paddy was mainly determined by the accumulated solar energy received, and which was expressed as a simple equation. The drying characteristics revealed to follow a constant rate drying type, and as the depth increased the more typical constant-rate drying pattern was observed. The relationship between the drying rate and bed depth was established with a simple exponential equation. The raking operation during the drying period showed a favorable effect both on the drying rate and the reduction of crack formation. Drying environments such as straw mat, concrete, ground, polyethylene film did not affect significantly the drying rate and rice quality. Considering the drying rate and quality, the optimum bed depth of mat paddy drying was around 6 cm.

• Applied Biological Chemistry
• /
• v.34 no.3
• /
• pp.258-261
• /
• 1991

In order to establish the optimum drying temperature of the heated air blast-grain circulation dryer, a 2 ton scale of paddy was used in this experiment. The temperatures of heated air used were 45, 50, 55, 60, 65 and $70^{\circ}C$. Moisture content of the paddy was reduced to 15% from 24% by drying. The higher air temperature, the shorter drying time and the less fuel consumed. The portion of cracked kernels was found to be low as $3{\sim}10%\;at\;40{\sim}55^{\circ}C$, but was very high to $28{\sim}30%\;at\;60{\sim}70^{\circ}C$. The germination percent was very high as 98 and 93% at 40 and $45^{\circ}C$, but it was decreased to 86 and 30% at 50 and $70^{\circ}C$, respectively. The recovery yield of milled rice from paddy was decreased by 1.76, 2.63 and 7.52% at 60, 65 and $70^{\circ}C$, respectively, compared with 75.86% as drying at $40^{\circ}C$. The higher heated air temperature, the less head rice of milled rice was recovered, and the decreased ratio was increased $60^{\circ}C$. The higher heated air temperature, the less alkali disintergation value and gel consistency of milled rice and the more water up take, expanded vlume, total solid in residual liquid and intensity of starch iodine blue value of residual liquid, and those tendency was found clear from $60^{\circ}C$ temperature of heated air.

• Food Science and Preservation
• /
• v.23 no.5
• /
• pp.689-695
• /
• 2016

In this study, the drying characteristics of medicinal (Ganoderma lucidum, Phellinus linteus) and edible (Pleurotus eryngii, Lentinus edodes) mushrooms were investigated. Their shrinkage ratios, Hunter's color values, and rehydration ratios were evaluated. Mushrooms were cut with rectangular (1 cm) and square ($1{\times}1cm$) shapes, and dried in the room temperature and at $50^{\circ}C$ and $70^{\circ}C$ using hot-air dryer. Initial moisture contents of edible mushrooms were higher than those of medicinal mushrooms, whereas final moisture contents were vice versa. Drying rate was the highest when drying at $70^{\circ}C$ (p<0.05). Moreover the drying rate of square slices was higher than that of rectangular slices (p<0.05). The shrinkage ratios of both medicinal mushrooms and edible mushrooms were the least when drying at $50^{\circ}C$ and $70^{\circ}C$, respectively (p<0.05). The changes of color values were less in the medicinal mushrooms dried in the room temperature than in the hot-air dried medicinal mushrooms (p<0.05). However, in case of edible mushrooms, the changes of color values were less in the hot-air dried mushrooms (p<0.05). Rehydration ratios of medicinal mushrooms dried at $50^{\circ}C$ was the highest (p<0.05). In contrast, rehydration ratios of edible mushrooms was the highest when drying in the room temperature (p<0.05). Thus, the hot-air drying at $50^{\circ}C$ would be suggested as the efficient drying method for both medicinal mushrooms and edible mushrooms.

• Korean Journal of Food Science and Technology
• /
• v.38 no.2
• /
• pp.188-196
• /
• 2006

Changes in physicochemical characteristics and functional components content of saengsik, uncooked food, were investigated to find efficient drying methods, one of important manufacturing process of saengsik. No changes in proximate compositions of all samples were observed during hot-air drying at 50, 55, and $60^{\circ}C$ and freeze-drying. Colors of carrot, Lentinus edodes, and sea mustard did not change, while a value of cabbage, L, a, and b values of Agaricus bisporos, and a value of laver changed slightly by hot-air drying at all temperatures and freeze-drying. Dietary fiber content increased by hot-air drying but not by freeze-drying. Reductions in vitamin C and ${\beta}-carotene$ contents of carrot, cabbage, sea mustard, and laver were higher by hot-air drying than by freeze-drying. Contents of total phenolics and lectin of L. edodes and A. bisporos were not affected by hot-air drying and freeze-drying. Contents of pectin, alginic acid, and porphyran in sea mustard and laver increased by hot-air drying.

• Food Science and Preservation
• /
• v.17 no.4
• /
• pp.507-512
• /
• 2010

The effects of pretreatment by freezing on juice expression and drying characteristics of Prunus mume fruit were investigated. Fresh fruit slices were frozen at $-20^{\circ}C$, thawed, and then either pressed (to yield juice) or dried. Fresh fruit slices were used as controls. Both juice yield and drying rate were higher when pre-frozen fruit was tested, compared to fresh fruit. The L and b color values were lower in the juice and dried powder of pre-frozen compared to fresh fruit. The a color value was higher in juice and powder prepared from pre-frozen fruit compared to fresh fruit. There was no significant difference in free sugar or organic acid content between juices and powders from pre-frozen and fresh fruit. None of soluble solid content, titratable acidity, or juice pH was affected by freezing pretreatment. The results suggest that such pretreatment may be useful to increase juice yield and drying rate. However, browning of juice and powder may be elevated.