• 동력기계공학회지
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• 제15권4호
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• pp.5-10
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• 2011

In case of using rapid vacuum-freeze drying for high quality dry flower of flowering plant, the morphological and physiological characteristics of dry rose showed as the following. The dry ratio of about 82% presented after 1 day in case of using rapid vacuum-freeze drying and it was reached that the optimum storage water content of general dry products was 18%. The dry ratio of about 89% presented after 4 days. This result indicates very short dry time comparing with natural dry time of 12 days. Also, the morphological characteristics of flowering plant in case of vacuum-freeze drying showed similar shape with real flower. The contraction decreased about 9% comparing with real flower under dry time of 72 hours. But the contraction in case of natural dry decreased 36% and showed noticeable difference. The brightness which affects physiological characteristics of dry flowering plant showed lower values according to the dry process and chromaticity was thick. After 4 days, natural dry was thick with about 2 times comparing with vacuum-freeze drying. In case of vacuum-freeze drying, the quantity of anthocyanin and chlorophyl which affect discoloration and bleaching of dry flowering plant showed the clear difference comparing with natural dry method due to the sublimation by vacuum after rapid freeze with short initial time.

• 설비공학논문집
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• 제2권2호
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• pp.105-111
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• 1990

The drying rate in freeze drying was obtained by experiment of garlic moisture contents depending on the drying time. Freeze drying experiment of garlic juice was carried out in vaccum freeze drier of laboratory scale by backface heating, and a mathematical model is also used to simulate the process of simultaneous heat and mass transfer in freeze drying to compare with experimental data.

• Journal of Biosystems Engineering
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• 제18권2호
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• pp.122-132
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• 1993

Effects of physical properties of garlic paste and freeze dry control parameters on the sublimation drying time were investigated to verify optimal operating method in freeze drying. A mathematical model of freeze drying by sublimation was suggested and used to estimate the drying time of garlic paste. Under various conditions, the drying time of garlic paste was calculated using the computer program for the suggested model. Among the physical properties of garlic paste, melting temperature was evaluated the most important factor in affecting the drying time. In supplying methods of the required heat energy for sublimation, it would be the best way to control the upper plate temperature and the lower plate temperature independently.

• 한국식품과학회지
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• 제34권1호
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• pp.91-95
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• 2002

본 연구의 목적은 동결건조된 김치를 시료로 선정하여 동결건조 시간이 건조된 김치제품의 미생물학적인 특성, 관능적 특성 및 다른 품질에 미치는 영향을 조사하여 "건조김치"의 제조에 적합한 동결건조 시간을 알아내는 것이다. 김치를 24, 48, 72시간 동결건조한 후, 건조제품의 젖산균수, pH, 관능적 특성, 파쇄도, 복원성 및 수분함량, 배추조직의 미세구조를 관찰하여 동결건조 시간이 건조김치의 품질에 미치는 영향을 조사하였다. 원시료에 비하여 24시간 건조시킨 제품의 생균수 및 pH가 현저하게 변화하였으나, 그 후에는 72시간까지 거의 변화가 없었다. 24시간 건조김치보다 48시간 또는 72시간 건조김치의 전반적인 기호성이 우수하였다. 동결 건조 시간이 24시간에서 48시간, 72시간으로 증가할수록 건조김치의 파쇄성은 증가하였다. 동결건조 시간이 경과할수록 건조김치의 복원성이 개선되고, 건조김치의 중량과 함유된 수분함량은 감소하였다. 본 실험의 조건하에서는 건조김치의 제조에 적합한 동결건조 시간은 미생물학적인 측면에서 보면 24시간도 큰 문제는 없으나, 관능적 특성과 건조제품의 품질특성의 측면에서 판단하면 48시간이 보다 바람직하였다.

• 대한기계학회논문집
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• 제17권8호
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• pp.2088-2098
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• 1993

A mathematical model of freeze drying by sublimation was suggested and used to estimate the drying time. Under the various conditions, the drying time of pure water and carrot was numerically calculated for the suggested model. Optimal policies of freeze drying were investigated experimentally in a laboratory freeze dryer. It was found that the shortest drying times could be obtained when the chamber pressure and condenser temperature were kept at their lowest values and the best method of heat transfer for sublimation was the conduction involving radiation. The sublimation drying period was finished when the bottom temperature of material could be reached at near $0^{\circ}C$ from frozen temperature.

• 한국식품영양과학회지
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• 제19권6호
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• pp.555-564
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• 1990

과실쥬스와 같은 자연 생산물의 동결건조에 있어서 가공처리중 휘발성분의 보유력 변화를 알아보기 위하여 headspace gas chromatography 기술의 특징을 이용하여 동결건조 속도, 초기 고형물의 함량 및 압력 등이 어떠한 영향을 미치는가에 대한 실험결과는 다음과 같다. 동결건조 속도가 휘발성분의 보유력에 대한 영향은 현저하였으며, 동결시간이 길수록 뚜렷하였다. 동결 건조 제품에서 휘발성분의 보유력은 동결에 의해 영향을 받았다. 동결건조 조건하에서 가장 많은 휘발성분의 손실은 동결건조 초기단계, 즉 1~2 시간 사이에서 일어났다. 휘발성분의 보유력은 초기 고형물의 함량이 많을수록 높았다. 동결속도가 빠를 때보다는 늦을 때가 휘발성분의 보유력이 높았으며 높은 압력에서보다 낮은 압력에서 높았다.

• Journal of Pharmaceutical Investigation
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• 제40권3호
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• pp.161-166
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• 2010

A fast dissolving tablet was developed using the freeze-drying technique. Hyeonggaeyeongyotang was selected as a model oriental medicine. Formulation and processing parameters were studied to obtain freeze-dried tablet with high drug loading, good palatability, and fast disintegration time. $Kollidon^{(R)}$ CLM served as both matrix former and taste masking agent. Ethanol used as co-solvent, decreased the disintegration time of tablet. Aspartame was employed to impart better taste. Drying condition was found to have a major effect in the morphology of the tablets. Freeze-drying process was optimized to decrease the processing time and improve the appearance of the tablets.

• 한국환경과학회지
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• 제17권11호
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• pp.1227-1233
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• 2008

The effect of freeze drying and fixatives in post-treating freeze drying on the morphological properties of the rose (Rosa hybrida L.) petal were investigated for the production of high quality of freeze dried rose. The morphology including form and color of the dried flowers of cut rose were depended on the drying methods. The drying time was extended due to their density and water content, and was shorter in the freeze drying than that in the natural and hot air drying. Freeze dried process for dried flowers took 2 days in a freeze dryer and did not cause shrinkage or toughening of rose petal being dried, preserving its natural shape and color. The diameter of freeze dried flowers showed little reduction compared to fresh flowers. In Hunter color values of petals of freeze dried flowers, L and a values were high and showed little variations in comparison to fresh petals. Freeze drying led to a noticeable increase in anthocyanin contents in petals, suggesting that anthocyanin contents play an important role in the acquisition of freezing tolerance. Exposure of flowers to freeze drying was accompanied by an increase in the carotenoid content. In the post-treating freeze drying, epoxy resin, a fixative, applied alone or in combination to petals of freeze dried flowers showed efficient coating for the protection from humidity and sunlight. Combined application of epoxy and acetone to freeze dried petals permitted maintenance of natural color and excellent tissue morphology, showing color stability and shiny texture in surface of petals. These findings suggest that application of fixatives to freeze dried rose petals improves the floral preservation and epoxy coating provides good quality in the freeze dried flower product.

• Clinical and Experimental Reproductive Medicine
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• 제51권1호
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• pp.42-47
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• 2024

Objective: This study evaluated the effects of temperature and storage time on the quality and DNA integrity of freeze-dried sperm from individuals with normozoospermia. Methods: Normal sperm samples from 15 men aged 24 to 40 years were studied. Each sample was divided into six groups: fresh, freezing (frozen in liquid nitrogen), freeze-dried then preserved at room temperature for 1 month (FD-1m-RT), freeze-dried then preserved at room temperature for 2 months (FD-2m-RT), freeze-dried then preserved at 4 ℃ for 1 month (FD-1m-4 ℃), and freeze-dried then preserved at 4 ℃ for 2 months (FD-2m-4 ℃). The morphology, progressive motility, vitality, and DNA integrity of the sperm were evaluated in all groups. Results: In all freeze-dried groups, sperm cells were immotile after rehydration. The freeze-dried groups also showed significantly less sperm vitality than the fresh and frozen groups. Significantly more morphological sperm abnormalities were found in the freeze-dried groups, but freeze-drying did not lead to a significantly higher DNA fragmentation index (DFI). The DFI was significantly higher in the FD-2m-RT group than in the other freeze-dried groups. Conclusion: The freeze-drying method preserved the integrity of sperm DNA. The temperature and duration of storage were also identified as factors that influenced the DFI. Accordingly, more research is needed on ways to improve sperm quality in the freeze-drying process.

• 한국식품과학회지
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• 제25권4호
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• pp.313-320
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• 1993

동결건조에서 승화 건조시간을 예측하기 위하여 수학적 모델링과 지배방정식을 설정하고, 당근즙을 대상으로 수치계산하여 실험값과 비교한 바, 수분함량이 많은 동결건조품에서 단위면적당 승화량을 높일 수 있는 재료의 두께는 전도 열전달 방식에서 5mm이었으며, 양면 복사방식에서는 10mm이었다. 또한 동일한 압력에서 응축기 온도가 낮을수록 당근즙의 승화시간은 짧았고, 압력이 높을수록 승화시간은 선형적으로 증가하였다. 그리고 동결건조 효율이 가장 좋은 열전달 방법으로는 전도 및 복사방식으로 상, 하의 플레이트 온도를 $T_x{\leq}T_m$와 $T_m{\leq}T_x$의 제한 조건하에서도 별도 제어하는 방식이었다.