• Food Science and Preservation
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• v.16 no.5
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• pp.714-718
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• 2009

Polyphenols are naturally occurring antioxidants and play many important roles in human health. Grape leaves have not yet been reported to contain the antioxidants. In this study, the physicochemical properties of powders from young grape leaves, obtained after hot-air or vacuum freeze drying, were analyzed. Weight loss rangedfrom 76-80%, but no difference was found between samples prepared by hot-air orvacuum freeze drying. The L-, a-, and b- values of grape powder all fell upon hot-air drying. Quercetin, resveratrol, catechin, and epicatechin were detected in all cultivars. The contents of the four polyphenols were generally higher in powders obtained by vacuum freeze dryingthan in those prepared by hot-air drying, indicating that vacuum freeze drying is better for optimal preservation of polyphenols. None of three polyphenols assayed was found in some cultivars or after certain drying treatments. Based on physiochemical properties, our findings suggest that powders obtained after vacuum freeze drying are optimal for industrial use.

• Journal of Biosystems Engineering
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• v.12 no.1
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• pp.39-44
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• 1987

Measurement methods of moisture content were compared with 7 dried vegetables (red pepper, onion, green onion, garlic, ginger, carrot and radish). The moisture contents of dried vegetables having different moisture contents were determined by atmospheric oven drying, infrared balance, vacuum oven and Karl Fisher methods. Vacuum oven and Karl Fisher methods gave the relatively agreed results and considered to give the accurate moisture content. Atmospheric oven drying and infrared balance methods resulted in higher moisture content than methods mentioned above, because of the thermal decomposition of solid. Calibration of the moisture data of atmospheric oven drying method into the vacuum oven data was undertaken. The thermodecomposable solid fraction was high in onion, radish, green onion and carrot, and was in the range of 8.0-11.7% of the total solid in these products.

• Journal of the Korean Wood Science and Technology
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• v.29 no.1
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• pp.9-15
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• 2001

Specific energy curves for water removal in vacuum-press drying of different thick softwoods of red pine (Pinus densiflora), white pine (Pinus koraiensis), larch (L. leptolepis) and Western hemlock (Tsuga heterophylla) were split into three sections: increased slowly, fairly constant, and increased rapidly. Calculated specific energy for 3, 5, 7, 9 and 11cm thick lumber was a value of 0.483, 0.649, 0.814, 0.977 and 1.138kWh/kg of water, respectively. Specific energy almost linearly increased as lumber thickness increased, and specific energy for severe schedule was less than that for mild schedule. Average specific energy was 0.712kWh/kg and vacuum-press drying consumed less energy as compared with any other drying methods.

• Journal of Ginseng Research
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• v.14 no.3
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• pp.353-356
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• 1990

The isolation of volatile compounds by vacuum-distillation with freeze-drying was tested 1 with fresh ginseng roots. The roots were frozen at-8$0^{\circ}C$; they were dried at-4$0^{\circ}C$ tinder vacuum(40 tory), for 24 hours; and the ice condensed at the silrface of condenser in the freeze-dryer was thauved at room temperature. The ether extract of the resulting aqueous solution was analyzed by gas chromatography (GC) equipped with a flame ionization detector (FID) or a nitrogen-phosphorils detecto(NPD) and by gas : chromatography/mass spectrometry(GC/MS). More than forty peaks were observed in the CG(FID) profile. and more than ten peaks were observed in the GC(NPD) profile. Among them, thirteen components 1including one aldehyde, four hydrocarbons, two esters, folly alcohols, and two vyrazines were identified: six components the molesuiar ions of which were m/z, 204 were estimated to be a series of azulene compounds; and the other components unidentified were estimated to have molecular weights of lower than 254. Therefore, the freeze-drying technicue is thought to be usefu1 for the isolation of volatile compounds of such low molecufilar weights from vegetables, fruits and biological fluids as well as fresh ginseng roots under the tested conditions.

• Journal of the Korea Furniture Society
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• v.17 no.1
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• pp.1-10
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• 2006

Movement behavior, shrinkage and equilibrium moisture content (EMC), in this experiment reflected a change of hygroscopicity mainly affected by continuously compressive load during radio-frequency/vacuum (RF/V) drying and humidity changes during equilibrating. As a result of interaction of the compressive load and moisture content changing under the RF/V condition, the shrinkages in loading direction were significantly increased while those perpendicular to loading direction were decreased. The shrinkages were affected most in tangential, and least in longitudinal direction. The shrinkages showed higher values in continuous drying than in intermittent drying. In the direction of increased shrinkage, all the movements were also increased, for example, the tangential movement for the loaded-RS and the radial movement for loaded-TS; in the direction of decreased shrinkage, all the movements except the tangential movement for the loaded-TS were decreased such as the tangential and radial movements for the loaded-ES, and the radial movement for the loaded-RS, comparing with those of the load-free. EMCs of the loaded specimens were all higher than that of the load-free specimen, and the highest for the loaded-TS, the lowest for the loaded-ES. The transverse hygroscopicity of specimen was reduced for the loaded-ES, but increased for the loaded-TS.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.3
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• pp.393-398
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• 1998

The loss of ascorbic acid in dried red pepper leaves prepare with different drying methods of air-, oven-, microwave oven-, and vacuum drying with blanching or without was determined by a HPLC method. Vacuum drying showed the least loss of ascorbic acid than the other drying methods. Additionally, the feasibility of near infrared reflectance spectroscopy(NIRS) to determine the contents of ascorbic acid in the red pepper leaves was studied. NIRS was found to be an efficient way of determining ascorbic acid contents in red pepper leaves, requiring only 30 seconds of an analytical time.

• Korean Journal of Medicinal Crop Science
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• v.22 no.4
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• pp.255-261
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• 2014

Cosmetic activities of the leaves of Curcuma longa L. were compared according to different drying methods, to expand the use of the by-products of Curcuma longa L. The highest extraction yield of 29.4% was obtained from vacuum drying process (VD), whose value was very close to 29.2% from freeze drying process (FD). Relatively lower extraction yield were observed as 24.5% and 25.3% from the raw leaf (RL) as control and hot air drying process (HD). The cytotoxicity was observed lower FD and VD than RL and HD. It shows that cytotoxicity was closely related to cosmetic activities such as tyrosinase and melanin inhibition activities by showing much better cosmetic activities of the extracts from both FD and VD than those from the RL and HD. It was interesting that was differences of the cosmetic activities and cytotoxicity between FD and VD, which implies that VD method should be a more efficient process than FD method in terms of drying time and operation costs: 6 hours vs 24 hours and 3-5 times higher extraction costs in drying. It was observed that VD is more excellent dry method than others. This result could be utilized to effectively dry other soft plant biomass.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.4
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• pp.460-469
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• 2010

In spite of the global-class aquaculture and fishing technology of our country, the processing technologies are lags behind the other nations relatively. The processed marine products are mainly frozen foods, canned goods, salty food (fermented fish products), fish paste products (boiled fish paste), and we can see that the high-value dehydrated foods by drying are very few. These problems are considered to be caused directly by the lack of drying technologies. This paper is concerned to the experimental results of drying heat transfer characteristics for the green energy type vacuum dryer for the high quality sea foods production.

• The Korean Journal of Food And Nutrition
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• v.12 no.3
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• pp.258-264
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• 1999

This study was carried out to investigate the status in weight loss yield of edible meat quality and free amino acid contents of the snow crab(Chionoectes japonicus) by steaming and various drying treat-ment. Change of body weight loss in steaming treatment sample were 20.48∼26.72% and yield of edible meat of steaming sample was higher than raw sample(p<0.05) The pH value was increased with steam-ing and drying and pH of trunk meat was more increased than leg meat. Volatile basic nitrogen(VBN) content of vacuum dried sample was highest and VBN of hot-air and freezing dried sample were about 10mg%. Content of vaccum dried sample wre 41.33 and 48,56mg%. Thirty kind of free amino acids dectected in the snow crab and changes of free amino acid in leg meat were markedly reduced by vacuum drying and the reducing ratio of leg meat by freeze drying was little. The major free amino acid of leg and trunk meat were 39.94% 46.78% respectively. The formation of flavor free amino acid in freezing dried sample were high but its hot-air aried sample were small.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.1
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• pp.21-25
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• 2014

A drying machine for discarded Citrus scrap was developed in this study. The Citrus produced in Jeju Province was treated as wastes (a) after making a beverage, such as drinking juice, and (b) if the size of the product did not fit with its agricultural product criteria. Various types of drying machine were developed in this study, and different kinds of technologies were combined improve the performance. To enhance the performance, the system was maintained in a vacuum state, and a high frequency micro wave was activated to the waste Citrus scrap, to heat up the moisture inside the Citrus kernels. The frequency of the micro-wave was 2.6 GHz, which is the resonant frequency of the molecules. Experiments were conducted with a vacuum of 50, 100, 150, 300, 500, and 700 mbar. The waste Citrus scrap has two types of status : (a) original scrap, and (b) mixed with blender. As results, specimen (a) shows a 0.13 g/sec evaporation rate, while specimen (b) shows a 0.19 g/sec rate, at 50 mbar of environment vacuum condition. For the drying efficiency, specimens (a) and (b) show 0.15 g/W and 0.24 g/W, respectively.