• Journal of the Korean Home Economics Association
• /
• v.42 no.5
• /
• pp.193-203
• /
• 2004

This study examined the changes in the chemical components and antioxidant activity of Ecklonia cava according to the drying methods. As chemical components, the concentrations of minerals(K, Ca, Na, Mg, Fe, Cu, Mn and Zn), vitamins(vitamin C, ${\beta}$-carotene and ${\alpha}$-tocopherol) and the total polyphenols were analyzed. In additions, the antioxidant activity was determined by measuring the free radical(DPPH radical, superoxide anion radical, hydroxyl radical and hydrogen peroxide) scavenging activity and the linoleic acid peroxidation inhibitory activity. The mineral content was not affected by the drying methods. However, more vitamins were lost and the total polyphenol concentration was reduced as a result of sun-drying than by the other drying methods used. More of the total polyphenol was preserved by freezing-drying than by any of the other drying methods, which meant that there was a higher antioxidant activity after freeze drying.

• Korean Journal of Food Science and Technology
• /
• v.19 no.1
• /
• pp.5-11
• /
• 1987

Lipid oxidation is one of the major factors affecting on deterioration of nutritional quality in boiled and dired fish products. In this paper, the relationship between oxidized products of lipid, brown pigments, and available lysine during the drying and the storage of boiled and dried shrimp (Metapenaeus joynri) was investigated. Fresh shrimps were bioled in 5% sodium chloride solution. The boiled shrimps were treated in two ways, sun drying and hot air drying at $30{\pm}5^{\circ}C$. And the two dried products were stored at $30{\pm}5^{\circ}C$ for one month. The results obtained are as follows: TBA value increased up to 20 days and hereafter gradually diminished. POV was increased for processing and increased 15 days of storage. TBA value and POV increased rapidly while available lysine diminished during the sun drying and hot air drying. Brown pigment was increased during lipid oxidation but it was not statistically significant. This result implicits that the drying had greatly influenced on the oxidation of lipid and makes amino acids 'unavailable'. But there is no remarkable difference between the sun dried shrimps and the hot air dried shrimps so far as the lipid oxidation and available lysine.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.14 no.2
• /
• pp.95-98
• /
• 1985

This study was carried out to investigate changes in the compositions of fatty acids according to the different drying methods of raw mugwort. Raw mugwort from Kang-wha was dried with four methods such as sun-drying, shady sun-drying, heated oven-drying and freeze-drying. Total contents and fatty acid compositions of the ethyl ether extracts from the dried mugworts were examined. Total contents of the ethyl ether extracts showed remarkable differences with drying methods; freeze-dried mugwort had the highest content (5.60%), while oven dried mugwort revealed the lowest content (2.45%). Eleven fatty acids and four unknown peaks were identified by gas-liquid chromatography; major fatty acids were linoleic acid, linolenic acid and palmitic acid. Fatty acids of mugworts dried by 4 different methods were the same in kinds, but different in their compositions. The content of polyunsaturated fatty acids $(C_{18:2}+C_{18:3})$ was the highest and the loss of low volatile fatty acids was the least in mugwort dried by the freeze-drying method. The volatile fatty acids considerably decreased in oven-dried mugwort. However, the contents of polyunsaturated fatty acids were a little higher in oven-dried mugwort than in sun-dried and shady sun-dried mugwort, and the lowest in sun-dried mugwort.

• Korean Journal of Food Science and Technology
• /
• v.46 no.3
• /
• pp.303-308
• /
• 2014

This study determined the antioxidant levels and activities of hot water aronia extracts by different drying methods such as sun drying, sun drying after steam treatment, freeze-drying, and oven drying. The total polyphenol content, calculated as gallic acid equivalent, was the highest in the freeze-dried sample (910 mg), followed by sun-dried after steam treatment (779 mg), sun-dried (769 mg), and oven-dried (757 mg) samples. Similar patterns were observed for the total flavonoid and anthocyanin contents. Freeze-dried aronia samples contained the highest polyphenol, flavonoid, and anthocyanin contents as compared to the samples dried by other methods. All antioxidant activities were found to increase in a dose-dependent manner. For the hot water-extracted freeze-dried aronia powder (200 mg/mL), the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radicalscavenging activities were 65.5% and 61.7% and the hydroxyl and superoxide anion radical-scavenging activities were 50.5% and 52.1%, respectively. These results suggest that comparatively, freeze-drying is a better method for preserving the bioactive components and the antioxidant activities of aronia.

• Journal of the Korean Society of Food Culture
• /
• v.19 no.2
• /
• pp.200-208
• /
• 2004

This study was performed to investigate the change of biologically functional compounds and antioxidant activities in Hizikia fusiformis with drying methods. As biologically functional compounds, the contents of minerals(K, Ca, Ma, Mg, Fe, Cu, Mn and Zn), vitamins(vitamin C, ${\beta}-carotene\;and\;{\alpha}-tocopherol$) and total polyphenol were analyzed. And antioxidant activity was determined through free radicals(DPPH radical, superoxide anion radical, hydroxyl radical and hydrogen peroxide) scavenging activity and linoleic acid peroxidation inhibitory activity. The contents of minerals were not affected by drying methods however vitamins and total polyphenol were lost more by sun-drying than other drying methods studies. Total polyphenol was preserved by freezing-drying than other drying methods studies, resulting in high antioxidant activities.

• Korean journal of food and cookery science
• /
• v.31 no.5
• /
• pp.596-604
• /
• 2015

This study investigated changes in the chemical properties and antioxidant activity of dried shredded radish (Raphanus sativus L.). Shredded radishes with a thickness of either 3.5 mm or 7.0 mm were dried using hot air at $45^{\circ}C$ or were sun dried. The degree of browning for the 3.5 mm sun dried radish, the 7.0 mm sun dried radish, the 3.5 mm hot air dried radish and the 7.0 mm hot air dried radish was 0.12, 0.14, 0.04 and 0.04, respectively. The DPPH radical scavenging activity (EDA%) of the hot air dried radish had a higher value than the sun dried radish. In contrast, the ABTS values of the sun dried radishes were higher than the hot air dried radishes. The total polyphenol content of the 7.0 mm and 3.5 mm hot air dried radishes reached high values of 15.99 and 11.62 mg/g, respectively. The total polyphenol contents of the 7.0 mm and 3.5 mm sun dried radishes were 9.63 and 6.77 mg/g, respectively. In sensory evaluation of the stir-fry dried shredded radishes, the 7.0 mm hot air dried sample scored the highest in terms of smell, color, gloss and overall preference. In conclusion, hot air drying ($45^{\circ}C$) and a thickness of 7.0 mm were found to be the optimal conditions for dried shredded radish and stir-fried dried shredded radish products.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 1993.10a
• /
• pp.906-911
• /
• 1993

There will be about 0.25 to 0.3billion tons of grain product including rice, wheat and corn etc. each year in China. An energy analysis on grain drying system on which electricity , oil , coal or sun power and batch, tower with thick or thin layer of grain, infra red radiation. fluidized flowing types grain drying systems were made and compared for the sake of energy saving is shown in this paper.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 1993.10a
• /
• pp.896-905
• /
• 1993

Thin-layers of wheat and barley are dried at near-ambient temperatures(3.5$^{\circ}C$ -5$0^{\circ}C$) in order to obtain the intrinsic drying data. The well established apparatus was modified to enable it to record all the sample weight data in still air by using a purpose -built automatically controlled sliding valve. The air could be diverted in less than 0.5seconds and a 7 second period was required to attain a steady weight reading. With this apparatus, very smooth drying curves were obtained. The data of sample weight , drying temperature and dew point temperature wee recorded continuously . The drying process was terminated when the moisture content change in 24 hours was less than 0.004 d.b. This was achieved by drying a sample for about a week . The final points were recorded as the dynamic equilibrium moisture content(EMC). The drying data were than fitted to the exponential Newton model and the dynamic EMC data were fitted to the Modified-Chung-Pfost Model . All the fitted parameters are given and comparison is made with previous published data. The comparisons who that the current drying constants are lower than the previous data, the dynamic EMC data obtained for wheat and barely agree with the previous data. The results show that to obtain the drying constant in the exponential Newton model, adequate drying time is necessary.

• Journal of the Korean Wood Science and Technology
• /
• v.35 no.4
• /
• pp.45-51
• /
• 2007

To investigate the drying behaviors of the water-based natural coating made by rosin during drying, the mass transfer and optical change from speckle image and speckle rate were measured and the relationship between two analysis methods were investigated. At a linear scale, the speckle rate measured by HORUS related with the mass transfer of coating during drying, and the speckle rate at a log scale was included not only drying time, but also drying mechanism of coating during drying. Therefore, the HORUS was an available method to investigate the drying time and drying mechanism of coating during drying.

• Korean Journal of Food Science and Technology
• /
• v.36 no.1
• /
• pp.25-31
• /
• 2004

Characteristics of good-quality red pepper powder produced using $N_{2}$-circulated low-temperature drying method were compared with those made through conventional sun and hot-air drying methods. Kimchi and kochujang were prepared with different types of red pepper powder, and their physicochemical and sensory properties were compared. Results revealed Hunter L (lightness), a (redness), and b (yellowness) values of $N_{2}$-circulated low temperature-dried red pepper were highest. Absorbance of crude capsanthin in hot air-dried red pepper powder ($0.584{\pm}0.001$) was significantly lower than sun-dried ($0.848{\pm}0.001$) and $N_{2}$-circulated low temperature-dried products ($0.832{\pm}0.002$. Use of $N_{2}$-circulated low-temperature drying method resulted in the highest amounts at reducing sugar and total vitamin C. Capsaicin content of $N_{2}$-circulated low temperature-dried products were higher than hot air-dried ones. The aL values of kochujaug made with sun-and low temperature-dried red peppers were higher than that of kochujang made with hot-dried red peppers. Physicochemical and sensory evaluation results showed red pepper powders made using $N_{2}$-circulated low-temperature drying method have the best quality among all samples tested.