• Korean Journal of Food Science and Technology
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• v.42 no.2
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• pp.147-154
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• 2010

Gulbi, made of fresh yellow corvenia (Psendosciaena manchurica) that has been salted and dried, is one of the most popular traditional marine foods in Korea. The objective of this study was to develop a method to safely manufacture Gulbi with low levels of oxidation and contamination, by a hot air drying method. Changes in total acidity, pH, salt concentration, thiobarbituric acid-reactive substance (TBARS) and volatile basic nitrogen (VBN) were measured during drying at 30, 35 and $40^{\circ}C$ for 15 days in a hot air-dryer using a semi-dried method. Acidity increased with increasing drying time at all drying temperatures. The pH decreased gradually with increasing drying time. Salt concentration was increased as drying time increased at all drying temperatures due to moisture loss. The VBN increased as drying time increased for all drying temperatures. Data indicate that the drying at $35^{\circ}C$ appears to have a significant sensory and physicochemical advantage in Gulbi products.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.5
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• pp.605-611
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• 2008

Antioxidant activity of wa-song (Orostachys japonicus A. Berger) was analyzed to clarify the influence of extractive solvent and drying method such as sun, hot-air and freeze drying. The contents of total phenols and flavonoids were significantly higher in 95% ethanol extracts than water extracts. Ability of reducing power and DPPH radical, hydroxyl radical and nitrite scavenging ability were higher in the order of hot-air dried sample> freeze dried sample> sun dried sample and these abilities were also higher in 95% ethanol extracts than water extracts. In conclusion, antioxidant activities of wa-song extracts were in proportion to the contents of total phenols and flavonoids. Also, hot-air drying is the superior method for the enhancement of antioxidant activity of wa-song.

• Food Science and Preservation
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• v.3 no.2
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• pp.137-143
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• 1996

In order to produce the high-quality of dried red pepper with respect to a color and a taste we developed a automatic drier equipped with combined several heat energies(ADCHE). and compared the quality of ADCHE-treated red pepper with that of the pepper treated with conventional dryings such as natural, hot-air, and far-infrared ray dryings. The results obtained were as follows : (1) The contents of capsanthin varied significantly with drying methods within the range of 1.7 to 6. 4mg/g dry weight. The capsanthin level of red pepper treated with far-infrared ray drying was higher than that of the pepper treated with ADCHE showed the highest at 51.46mg/g dry weight of three drying methods. (2) As a result of determination of color intensity of-red-pepper using-a colorimeter, the red color intensity of the peppers was affected by drying methods irrespective of drying temperature, and especially a value of red pepper treated with ADCHE was appeared to be 19. 1, indicated that this pepper have the most bright color intensity. (3) The contents of soluble browing subatances increased with a increase in drying temperature, but L* value of red pepper treated with ADCHE was appeared to be 0.187, indicated that this red pepper have the most clear red color (4) The changes of capsanthin level of red pepper according to drying methodes did not show significantly, but generally a decreasing rate of capsanthin levels were lower in that order ADCHE

• Food Science and Biotechnology
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• v.18 no.6
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• pp.1464-1469
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• 2009

Jiwhang (Rehmannia glutinosa), one of the most widely used medicinal herbs, was dried with various methods such as sun drying, hot air drying, vacuum drying, and freeze drying methods, and their effects on the antioxidant capacity in relation with the content of total phenolic compounds were studied with a steamed-and-dried rehmannia (sookjiwhang) for comparison. Generally, total phenolic contents decreased significantly by all of the drying treatments except the steamed-and-dried rehmannia, in which total phenolic contents increased 2.4 fold compared with fresh rehmannia. Content of verbascoside, a functional phenolic compound, was the highest in the freeze-dried rehmannia ($177.97{\pm}0.02\;{\mu}g/g$ d.m.) followed by vacuum-dried ($105.55{\pm}0.07\;{\mu}g/g$ d.m.), hot air-dried ($23.01{\pm}0.02\;{\mu}g/g$ d.m.), and sun-dried ($4.89{\pm}0.13\;{\mu}g/g$ d.m.) ones comparable to the fresh rehmannia ($80.15{\pm}1.26\;{\mu}g/g$ d.m.). Antioxidant capacity determined by both 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azinobis (3-ethyl-benzthiazoline-6-sulphonic acid) (ABTS) methods agreed with the result of total phenolic contents, that is, the antioxidant capacity was the highest in the steamed-and-dried rehmannia followed by fresh rehmannia, vacuum-dried, hot air-dried, sun-dried, and freeze-dried ones. Conclusively, the total phenolic contents and antioxidant capacity of rehmannia were greatly affected by the drying methods used.

• Food Science and Preservation
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• v.22 no.1
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• pp.56-62
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• 2015

In this study, the quality characteristics of different drying methods of Aronia melanocarpa, which contains large amounts of bioactive substances, were investigated for the improvement of their practical use. During the drying period, the weight reduction was the highest with vacuum freeze drying (81.6%). The water content was reduced to the maximum level when vacuum freeze-drying was used. With regard to the color value measurement results, there were no significant differences in the $L^*$ value. Values of $a^*$ and $b^*$ were increased in vacuum freeze drying and cold air drying, but decreased in hot air drying. The hardness was increased dramatically after 36 hours of hot air drying, while with cold air drying, it increased slowly until 132 hr and increased rapidly after 132 hr. The dried yield was the highest with cold air drying (24.2%). As for the general component analysis results of Aronia melanocarpa, the moisture content was the lowest, and the crude protein and crude fat contents were the highest with vacuum freeze drying. No difference in pH value was shown among the dried Aronia melanocarpa obtained from the different drying methods, but the sugar content was the highest with vacuum freeze drying. The mineral content was the highest with cold air drying, and K, Ca, Mg, and Na were the major minerals. The free sugar content of dried Aronia melanocarpa was found to be 5.92~20.59 g/100 g, and the highest free sugar content was found with vaccum freeze drying.

• Food Science of Animal Resources
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• v.42 no.5
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• pp.861-873
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• 2022

The drying of duck blood provides safety and commercial benefits, but each drying method has its own characteristics. Moreover, information on the effects of diverse drying methods on the quality of duck blood is limited. This study aimed to investigate the effects of various drying methods on the chemical and functional properties of duck blood. The physicochemical characteristics and functional properties of duck blood subjected to spray drying (SD), freeze drying (FD), vacuum drying (VD), and hot air drying (HD) were examined. The carbonyl content of FD duck blood powder was the lowest and the thermal stability was higher than that of the other treatments (p<0.05). The gel obtained from spray-dried blood displayed the lowest malondialdehyde content. The hardness, gumminess, and chewiness were the highest in the heat-induced gel prepared from FD duck blood powder (p<0.05). The gel obtained from FD duck blood displayed a denser structure than the other gel samples. Taken together, the FD duck blood exhibited excellent chemical properties and processing suitability.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.12
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• pp.1680-1687
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• 2011

This study was performed to determine the effects of pretreatment and drying methods on the quality and physiological activities of garlic powders. Fresh garlic was boiled, baked, steamed or left untreated before hot-air drying or freeze-drying. Electron-donating abilities were higher in the untreated group for each drying method. Relative EDA of baked group was 32.8%, whereas those of the boiling and steaming groups were 12.4% and 20.1%, respectively. Nitrite-scavenging effects were slightly affected by processing methods. Polyphenol content of the processing group was higher in the hot-air drying than freeze-drying group, and it was significantly highest in the untreated freeze-dried group. The value of polyphenol in the baked group was significantly higher than those of the boiling and steaming groups. Tyrosine contents of garlic powder were higher in the hot-air drying than freeze-drying group, and it was significantly highest in the untreated group of each drying method. Antimicrobial activities of the garlic powders were higher in freeze-drying group compared to the hot-air drying group. Therefore, antimicrobial activities of garlic powder were affected by heating treatments.

• Food Science and Preservation
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• v.20 no.6
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• pp.894-898
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• 2013

This study was performed to provide the basic data for the prediction of the usefulness of onion with cold tolerance cultivated in Kangwon. The physicochemical properties and antioxidant activity of freeze-dried and hot-air-dried (40 and $60^{\circ}C$) onions were investigated. The moisture content of the raw onion was 90.55%. The crude protein and crude fat contents of the freeze-dried onions were slightly higher than those of the hot-air-dried onions ($40^{\circ}C$ and $60^{\circ}C$). As for the color values, the freeze-dried onion powder was highest in lightness (77.19), and the $60^{\circ}C$ hot air-dried onion was highest in redness (6.09) and yellowness (24.60). Moreover, the color difference (${\Delta}E$) between the freeze-dried and hot-air-dried ($40^{\circ}C$ and $60^{\circ}C$) onion powders was significant. The brown index was lower in the freeze-dried onion than in both hot-air-dried onions. The total phenol content and the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) scavenging activity of both hot-air-dried onions were higher than those of the freeze-dried onion. These results indicate that the freeze-drying methods protected the physicochemical properties of the onion powder, whereas the hot-air-drying method enhanced the antioxidant activity and the total phenol content of the onion powder.

• Journal of Korean Society of Forest Science
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• v.110 no.2
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• pp.244-253
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• 2021

This study aimed to investigate quality characteristics of hot-air dried persimmon during the drying period in 'Bansi' and 'Godongsi'. These cultivars were classified into four grades: 2L, L, M, and S based on the fruit weight. Weight loss, firmness, soluble solid content (SSC), and moisture contents were measured during the hot-air drying period. The weight loss significantly increased during the drying period (p<0.05), while there was no difference between cultivars. In the initial drying period, the firmness decreased due to softening during the ripening stage and increased significantly due to hardening during the water loss stage. Regardless of the cultivars, the SSC increased from 19.6% in the initial period to 55.3% at 12 days after drying. Moisture content statistically decreased in both cultivars over the whole drying period. It took 4 days and 8~10 days to produce semi-dried persimmon (45~55% moisture content) and dried persimmon (25~35% moisture content) in both cultivars. These results could be effectively used as basic data for producing high-quality semi-dried and dried persimmons using the hot-air drying method in 'Bansi' and 'Godongsi'.

• Journal of the Korean Wood Science and Technology
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• v.34 no.1
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• pp.7-14
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• 2006

Three-dimensional distribution and variation of moisture content of boxed-heart square timber of Pinus densiflora was investigated to find the safe and rapid drying methods. As results, microwave-drying method could dry the boxed-heart square timber with sectional dimension of $150{\times}150mm$ under 10% moisture content (MC) within 72 hours with less surface checks, compared with hot-air drying. In case of microwave drying, the MC distribution during drying had a close relation with the initial MC distribution. In case of hot air drying, however, it was independent on the intial one except for the intial drying stage.