• Food Science and Preservation
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• v.11 no.4
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• pp.516-521
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• 2004

The study was intended to develop a yam snack to increase the consumption and the added value of the yam which has many kinds of medicinal effects and functions. Moisture content of a freeze-drying yam snack was higher than those of hot wind drying and vacuum drying yam snack. However, carbohydrate content was opposed to it. The content of soluble proteins in freeze drying yam snack was 6.43 mg/100g, and lower than that those in hot wind drying and vacuum drying yam snack. The contents of total sugar and reducing sugar were not noticeably different by processing methods. The major organic acids of yam snack were malic, acetic, acids, and acetic acid. Citric acid were rich contented in hot wind and vacuum dried yam snack, but the content of malic acid in freeze dried yam snack was higher than those in hot wind and vacuum dried yam snack. The contents of the amino acids and total amino acids showed the highest contents in vacuum dried snack and the next came in hot wind dried snack and freeze dried snack order. The content of free amino acids were not different by processing methods. Total content of vitamin C were not different by processing methods, but a ascorbic acid was higher in freeze dried yam snack than those in other. The dehydroascorbic acid contents of the hot-air and vacuum dried snack was higher than those of the freeze dried snack, Potassium, sodium and magnesium were the main minerals of the yam snacks.

• Food Science and Preservation
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• v.21 no.5
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• pp.646-651
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• 2014

To evaluate the processing adaptability of burdock (Arctium lappa L) tea, the physicochemical properties of burdock tea treated with steaming and roasting were investigated. The tea treatments included hot-air drying after roasting (HDR, drying at $60^{\circ}C$ for 6 hr), steaming after hot-air drying (SHD, steaming at $100^{\circ}C$ for 10 min), and steaming and then hot-air drying followed by roasting (SHDR, roasting at $250^{\circ}C$ for 3 min). The physicochemical properties, antioxidant activities, and sensory properties of the HDR, SHD, and SHDR teas were measured in hot water, and the tea was extracted from each sample. The color values of lightness (L) and yellowness (b) were lower in the HDR and SHDR teas, and the total sugar content of the SHDR tea was significantly higher than that of the other teas. The ABTS and DPPH radical scavenging abilities of the SHDR tea with a 500 mg% concentration were significantly higher than those of the SHD tea. In the sensory evaluation, the SHDR tea was ranked significantly higher than the other samples as to its color, flavor, taste, and overall acceptability. The results suggest that SHDR can be applied to burdock tea to achieve high quality and functionality.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.4
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• pp.496-501
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• 2009

This study was carried out to investigate physiological functionalities of tea prepared by various thermal processing methods from Ixeris dentata root in order to elevate utilization of Ixeris dentata root as food. These methods included natural drying (ND), hot-air drying (HAD, $75^{\circ}C$), hot-air drying after steam (HADS, steaming at $95^{\circ}C$ for 30 min) and roasting after hot-air drying (RHAD, roasting at $140^{\circ}C$ for $2{\sim}3$ min). Physiological functionalities of tea prepared by ND, HAD, HADS, and RHAD were measured as hot-water extracts and each tea was extracted by 100 mL water on 1 g dried Ixeris dentata root powder. Electron donating abilities were the highest in HADS treatment at 98%. SOD-like activities were the highest in RHAD at 35.61%. Both ACE and tyrosinase inhibitory activities were the highest on ND treatment at 52.34% and 44.60%, respectively. Nitrite scavenging abilities of all treatment were the highest at pH 1.2 and the highest activity among them was on RHAD treatment at 50.5%.

• Journal of the Korean Wood Science and Technology
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• v.22 no.2
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• pp.61-70
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• 1994

This study was executed to find the applicability of press drying of tree disk by investigating the shrinkage and drying defect and to form appropriate model by comparing the actual moisture content(MC) and internal temperature in respect of drying time with calculated values based computer simulation to which was applied finite difference method. In press drying disk, heating period, constant drying rate period maintained plateau temperature at 100$^{\circ}C$ and falling drying rate period were significantly distinguished. Actual MC and internal temperature were analogous to those calculated at comparing points. Heat transfer model formed by Fourier's law using specific heat of moist wood and conduction coefficient considering fractional volume of each element of wood cell wall, bound water, free water and air showed applicability as basic data to developing heat expansion, shrinkage and drying stress during press drying. Also mass transfer model formed by Fick's diffusion law using water vapor diffusion coefficient showed applicability. Longitudinal shrinkage was developed by pressure of hot press and tangential shrinkage was restrained by hygrothermal recovery. The heart check, surface check and ring failure were occurred differently in species, but V-shaped crack didn't develop.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.1
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• pp.60-65
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• 2008

Chemical properties of barley leaf were investigated using different drying methods. Moisture contents of barley leaf were 75.22%, 7.54%, 2.57%, 6.74% and 8.91% for samples dried using raw, hot-air dryer, freeze dryer, shade dryer, vacuum freeze dryer and microwave dryer, respectively. Mineral contents were high Ca, Mg, Na, P, and K in barley leaf regardless of drying methods. Organic acid contents were oxalic acid, acetic acid, citric acid and fumaric acid with no differences between drying methods. Contents of vitamin C were 142.56 mg%, 629.23 mg%, 598.48 mg%, 657.62 mg% and 724.34 mg% for samples using raw, hot-air dryer, freeze dryer, shade dryer, vacuum freeze dryer and microwave dryer, respectively. Chlorophyll contents of barley leaf dried by hot-air dryer and shade dryer were higher than in that of freeze dryer and microwaves dryer. b-values were lower in freeze dryer than in that of other dried methods.

• Food Science and Preservation
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• v.22 no.5
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• pp.708-713
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• 2015

To provide the basic data to dry vegetate the sweetpotato leaves, the total contents of tannin, flavonoid and polyphenol in the methanol extract from the hot-air dried sweetpotato leaves were analyzed and DPPH radical scavenging activity, ABTS radical scavenging ability, nitrite scavenging ability, and others were comparatively analyzed. The total tannin content was decreased from Shinmi of 10.87 mg/g at $40^{\circ}C$ to 7.28 mg/g at $70^{\circ}C$ and the total flavonoid was decreased from Hayanmi of 55.37 mg/g at $40^{\circ}C$ to 39.63 mg/g at $70^{\circ}C$. That is, the low temperature drying contained more of these substances than in the high temperature drying. The DPPH radical scavenging activity was the highest in Shinmi and Hayanmi of 84.33% and 85.25% at $40^{\circ}C$, and the ABTS radical scavenging ability was a high value of over 80% in the treatment plot at $40^{\circ}C$. The nitrite scavenging ability was highest in Shinmi and Hayanmi of 76.15% and 73.74% at $40^{\circ}C$ but low at $70^{\circ}C$. That is, the antioxidant effect of the hot-air dried sweetpotato leaves was high in the sample of $40^{\circ}C$ and low in the sample of $70^{\circ}C$. Affected by the drying temperature, the high antioxidant effect is resulting from the little decrease of active ingredient when drying at low temperatures.

• Food Science and Preservation
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• v.31 no.2
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• pp.218-226
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• 2024

The oriental melon poses challenges in terms of long-term storage and distribution. Addressing these issues requires an extension of the storage life through appropriate processing. In this study, pretreated hot-air dried oriental melon slices (steamed and freeze-thawed) were prepared, and their physicochemical and organoleptic properties were examined. The control group (CON) consisted of hot-air dried oriental melon slices without pretreatment, while the steamed group (STG) and freeze-thawed group (FTG) consisted of hot-air dried oriental melon slices pretreated using steaming and freeze-thawing methods, respectively. The moisture contents detected in the CON, STG, and FTG groups ranged from 15.96% to 27.30%, with variations of 7.53 to 8.40 °Brix for the soluble solid contents. The CON group showed the highest Hunter color value for lightness (L^*) and the lowest value for redness (a^*). The texture profile analysis revealed the highest hardness and chewiness in the order of STG > CON > FTG. Considerable differences were observed in springiness and adhesiveness in the FTG group compared to the other groups. The organoleptic evaluation showed that the CON group had the highest sensory scores for overall preference. These findings indicate that the properties of hot-air dried oriental melon slices were influenced by physical pretreatments and that manufacturing these slices without pretreatment is the most effective method in terms of processing simplicity and cost efficiency.

• Applied Chemistry for Engineering
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• v.35 no.1
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• pp.42-47
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• 2024

Limonene was separated from waste citrus peels by a vacuum drying process with a venturi, and bioethanol was produced from dried citrus peels. Vacuum drying using venturi was very effective in removing moisture and limonene compared to hot air drying and natural drying. Citrus peels prepared by venturi vacuum drying were the most suitable for ethanol fermentation. The moisture and limonene content of the citrus peels dried for 15 hours were 17.0% and 3.2%, respectively. By venturi vacuum drying, essential oil containing limonene and floral water were obtained, respectively. The amount of essential oil separated by venturi vacuum drying was 4.21 mL essential oil/kg citrus peel, 79.9% of the separated essential oil was limonene.

• Journal of Power System Engineering
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• v.21 no.4
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• pp.62-69
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• 2017

Because the moist foods like anchovy were appeared lower quality by hot air that occurred the lipid oxidation, the drying system by using the cold air has been used widely. This study has been carried out on the performance improvement according to arrangement angle of baffle and location of air duct in the cold air dryer. The main parameters in this study are the arrangement angles which are without, $0^{\circ}$, $10^{\circ}$, $20^{\circ}$, $30^{\circ}$ and $40^{\circ}$, and the locations of air duct are without, front, center and back. For this study we have conducted the numerical analysis method using fluent in order to obtain the optimal condition of the drying performance. As the arrangement angle of baffle is increased, the relative humidity is proportionally decreased, the value at $40^{\circ}$ is 42.2% that indicate the reduction of about 4% than without it. After the air duct was installed, the decreased relative humidity is showed within 1%, therefore, the effect of air duct for improving the dry capacity is more large than the arrangement angle of baffle. Finally, we have obtained the optimal conditions that the arrangement angle is $40^{\circ}$ with the air duct for a cold air dryer.

• Proceedings of the Korean Fiber Society Conference
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• 1997.10a
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• pp.521-526
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• 1997