• Applied Microscopy
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• 제28권3호
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• pp.299-306
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• 1998

T-butyl alcohol (TBA) freeze-drying method originally designed by Inoue and Osadake (1989) was adopted to dry specimens for scanning electron microscopy and the results were compared with those dried using critical point dryer (CPD). Small pieces $(1\times1\times3mm)$ of liver of Sprague-Dawley rats were cut and fixed in 2% glutaraldehyde in 0.1 M sodium cacodylate buffer after anesthesia, and processed for scanning electron microscopy by several modifications of TBA freeze-drying methods and by the standard preparation method using CPD. The bile canaliculi and sinusoidal endothelial surface were observed. Tissue dehydrated with TBA before TBA freeze-drying preserved the structures best comparable to those prepared with CPD. This result suggests that combination of dehydration with TBA and TBA freeze-drying is a superior method to the original TBA freeze-drying method dehydrated with ethanol.

• 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.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 하계학술발표대회 논문집
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• pp.74-74
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• 2007

• 한국축산식품학회지
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• 제18권2호
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• pp.164-175
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• 1998

The objective of this study was to investigate the effects of freezing rate on ice crystal size and freeze-drying rate. Our experiments were carried out with self-manufactured freeze-dryer. Gelatin gels (2% w / w, 80$\times$20mm) were frozen unidirectionally (Neumann's model) from the bottom at -45, -30, -20, and -15$^{\circ}C$ and followed with freeze-drying. Under the upper conditions we measured freezing rate and the change of temperature and pressure during freeze drying. Freeze-dried gelatins were cut horizontally into 5 mm thickness from the bottom and measured their pore sizes. Also freeze-drying rate(primary drying) is estimated by measuring the temperature of sample and pressure of vacuum chamber. During freeze-drying, profiles of pressure and temperature were shown constant tendency regardless of freezing temperature and we could expect the end-point of freeze drying by considering pressure and temperature together. In temperature profiles, the point which temperature increased significantly was observed during freeze-drying. There is no relationship between freeze temperature and drying rate of primary drying in our model system. As freezing temperature increased, ice crystal size(X*) which correspond to 63.2% of cumulative frequency was increased and at the same freezing temperature ice crystal size(X*) was decreased with distance from the bottom of the sample. Freezing conditions have a strong influence on the quality of the final freeze-dried products in freeze-drying system.

• Journal of Ginseng Research
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• 제14권3호
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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.

• 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.

• 한국축산식품학회지
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• 제18권2호
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• pp.176-184
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• 1998

The objective of this study was to investigate the effects of freezing rate on aroma retention and to examine the mechanism of aroma retention during freeze drying process. Our experiments were carried out with self-manufactured freeze-dryer. Gelatin gels (2% w / w, 80${\times}$20mm) containing diacetyl(2mg/ml) were frozen unidirectionally (Neumann's model) from the bottom at -45, -30, -20, and -15$^{\circ}C$ and followed with freeze-drying. Under the upper conditions we measured freezing rate and the change of temperature and pressure during freeze drying. Freeze-dried gelatins were cut horizontally into 5 mm thickness from the bottom measured and diacetly contents. Besides, we observed the effect of the relative humidity of the diacetyl contents freeze-dried gelatin during storage. The retained diacetyl content was increased at high freezing temperature and in order of 0∼5, 5∼10, 10∼15, 15∼20 mm section from the bottom of the sample. It was observed that the retained diacetyl content was high in 15∼20 mm section. The retained diacetyl content and freeze-dried gelatin stored in the condition of high relative humidity was decreased significantly but in the low relative humidity case, was it decreased in small amount. The results of our experiment resents that the low temperature freezing and low humidity storing condition is effective for preserving aroma compound in food.

• 생명과학회지
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• 제27권7호
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• pp.754-759
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• 2017

100 l scale 미세조류 배양 시스템은 LED 광을 기반으로 자체 제작하였으며 Nannochloropsis oculata를 f/2 medium에서 광도($100{\mu}mol/m^2/s$), 배양온도($20^{\circ}C{\pm}1^{\circ}C$), LD cycle (12 hr)으로 배양하였다. 그 결과 LED blue (475 nm)에서 $100{\mu}mol/m^2/s$의 광도, 24 mg/l의 nitrate 농도에서 100 l 대량배양 결과 최대 biomass인 1.07 g/l를 배양하였다. 이렇게 배양된 미세조류에서 유용물질을 추출의 위한 추출방법을 확보하고 나아가 산물의 추출, 농축 및 건조공정 기술을 최적화하고자 하였다. 추출은 물리적인 방법인 sonicator, homogenizer를 이용한 파쇄법과 화학적인 방법인 0.5M HCl 파쇄법을 이용한 결과 chlorophyll a, chlorophyll b, carotenoid 함량은 물리적인 파쇄법인 sonicator를 이용 시 1.6, 0.5, 0.3 mg/g cell, homogenizer 이용 시 1.0, 0.6, 0.2 mg/g cell로 측정되었다. 0.5M HCl의 화학적 파쇄법 이용 시 chlorophyll a, chlorophyll b 함량은 0.9, 0.8 mg/g cell으로 측정되었다. 파쇄시간당 추출되는 영양물질이 가장 높은 시간은 15 min 파쇄 시 3.6 mg/g cell로 측정되었으며 acetone, methanol, ethanol의 3가지 용매 중 acetone이 3.6 mg/g cell로 효과적이 용매로 측정되었다. 농축은 2종류의 연속원심분리장비(tubular type, disk type), 마이크로필터, 필터프레스 4종 장비를 이용하여 시험한 결과 마이크로필터, disk type 연속원심분리기, Tubular type 연속원심분리기의 경우 16.0, 1.1, 0.5 g/l의 순으로 시간당 수율을 확인하였다. 건조공정 최적화를 위하여 열풍건조기, 진공건조기, 분무건조기, 동결건조기 등의 4종 시생산설비를 이용해 미세조류의 시간당 회수율 분무건조기는 Dextrin 0.5 kg이 첨가되면 회수율이 80%이지만 순도가 떨어졌고 동결건조기 회수율은 60%로 측정되었다.

• 한국식품과학회지
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• 제21권1호
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• pp.13-16
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• 1989

선택된 당류 및 전분 가수분해 물질을 기질로 사용하여 냉동건조에 의하며 acetaldehyde을 고정시키는 방법을 연구하였다. 단순기질 보다는 복합기질이 일반적으로 acetaldehyde를 고정시키는 능력이 좋았고. 특히 mannitol+lactose가 고정능력 면에서 가장 우수했다. 그리고 경계성 등을 고려할 때 mannitol+maltodextrin이 공업적으로 acetaldehyde를 고정하는데 적당할 것으로 평가됐다. 일반적으로, 기질 농도가 증가함에 따라 건조 중 acetaldehyde손실이 감소하였으며, 기질 농도 40%일 때 mannitol+maltodextrin 기질의 acetaldehyde 고정 능력이 가장 좋았다. 냉동건조 방법으로 acetaldehyde를 고정할 경우 건조실 압력이 낮을수록 건조 중 acetaldehyde 손실이 감소했다. 그러나 대량생산을 목적으로 할 때에는 0.5 Torr이하의 압력을 유지하는데 건조경비 부당이 과다하므로, 0.5 Torr정도의 건조실 압력을 유지하는 것이 적당할 것으로 평가됐다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.1321-1326
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• 2008

A study on the heat and mass transfer for the drying time in spray freezing drying process was experimentally presented in this paper. A spray freezing dryer for the production of an inhalable powder medicine is developed and an albumin solution as protein specimen is adopted. The freeze-drying for the albumin solution is tested in three different height of the particles piled up in a tray such as 2 mm, 5 mm, 7 mm, and the drying time is estimated as 10 h, 15 h, 22 h. From this results, the correlation is suggested and the drying time with various height of the particles piled up in a tray can be estimated. The assessment on the drying time is conducted thought a microbalance and the rate of water content is measured. The results based on temperature and weight are compared. The difference of the results happens due to the heat transfer from the lateral side of the vial. It is thought that the better estimation in drying time can be predicted by considering the heat transfer effect.