• Food Quality and Culture
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• 제2권2호
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• pp.61-66
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• 2008

The principal objective of this study was to assess the anti oxidative activities of Petasites japonicus against oxidative stress in bovine brain tissue. Petasites japonicus is found with a relatively widespread distribution, and is cultivated as a culinary vegetable in Korea. Petasites japonicus samples were dried either by freeze-drying or by hot air-convection drying ($80^{\circ}C$), then evaluated for their anti oxidative activity by measuring 1-dipheny-1,2-picrylhydrazyl (DPPH) radical scavenging, and by measuring thiobarbituric acid-reactive substances (TBARS) in brain homogenates subjected to $Fe^{2+}$-mediated lipids with or without the addition of botanical extract. Hot air convection-drying resulted in a slight increase in the extraction yield as compared with freeze-drying. However, total phenol and flavonoid contents in freeze-dried Petasites japonicas were significantly higher than those of hot air convection-drying. Freeze-drying increased the free radical scavenging activity of Petasites japonicas, leaves, and stems by 52.6, 28.6, and 248.0%, as compared with hot air convection-drying. Additionally, the $IC_{50}$ values measured by TBARS in hot air convection-dried Petasites japonicas, leaves, and stems were increased by 36.0, 31.6, and 15.9%, as compared to those of freeze-drying. Although anti oxidative activity was reduced slightly by heat processing in Petasites japonicas, freeze-drying for each portion of Petasites japonicus was the most appropriate for use as a functional food and pharmaceutical material.

• 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.

• 환경위생공학
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• 제22권1호
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• pp.57-66
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• 2007

Changes in the alliinase activity during the hot air drying and vacuum freeze drying of garlic samples treated as the whole, sliced and crushed state were investigated. The specific activity of alliinase in raw garlic was 8.52 units/mg protein. The activity in the whole garlic prepared by the hot air drying for 8 hrs was reduced remarkably to 5.22 units/mg protein with 61% remaining and to 4.25 units/mg protein with 50% remaining for 36 hrs. The activity in the sliced garlic prepared by the hot air drying for 36 hrs was reduced to 3.55 units/mg protein with 42% remaining and the activity in the crushed garlic prepared by the hot air drying for 36 hrs was reduced to 3.12 units/mg protein with 37% remaining. The garlic sample sliced or crushed was higher than the whole state in the efficiency of drying but was lower in the remaining activity of alliinase. The activity in the whole garlic prepared by the vacuum freeze drying for 8 hrs was reduced to 7.21 units/mg protein with 85% remaining and to 5.53 units/mg protein with 65% remaining for 36 hrs. The activity in the sliced garlic prepared by the vacuum freeze drying for 36 hrs was reduced to 4.55 units/mg protein with 53% remaining and the activity in the crushed garlic prepared by the vacuum freeze drying for 36 hrs was reduced to 4.16 units/mg protein with 49% remaining. The remaining activity of alliinase in the garlic samples prepared by the vacuum freeze drying was higher than the remaining activity in the garlic samples prepared by the hot air drying.

• Journal of Microbiology and Biotechnology
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• 제12권2호
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• pp.349-353
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• 2002

Two recombinant bacteria containing luxAB showed an increased tolerance to stresses associated with lyophilization, when the cells were freeze-dried in the presence of trehalose. In the case of a recombinant, UV2, only $2.5\%$ of the original bioluminescence and $2.7\%$ of the cell viability were restored after 4 h of freeze-drying without trehalose, which implies that the cells were heavily damaged during the dehydration. To improve these losses, trehalose was added before freeze-drying using different modes. Trehalose increased the bioluminescence and the viability of freeze-dried UV2 under all conditions tested, and it was also observed that the addition of trehalose to the cultures (final concentration of 0.08 M) for 15 min before the freeze-drying resulted in the restoration of $45\%$ of the original bioluminescence and $50\%$ of the cell viability. Trehalose also showed a similar efficacy with the other luminescent recombinant, YH9. Therefore, it was tentatively concluded that trehalose played a role as a protective agent in the freeze-drying of bacterial cells.

• 한국식품영양학회지
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• 제30권3호
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• pp.609-617
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• 2017

This experiment was carried out to enhance the availability of blackberry. Since it is difficult to use blackberry as a fresh fruit, we investigated the quality characteristics of blackberry powder obtained by various drying methods (freeze drying and hot-air drying at $40{\sim}80^{\circ}C$). The L- and b-values of freeze-dried powder was higher than hot-air dried powder. The pH (3.2) was lowest and the acidity (14.4%) was highest in freeze-dried powder. In freeze drying, the brix degree was $65.7^{\circ}Bx$, but it increased from $54.7^{\circ}Bx$ to $68.5^{\circ}Bx$ with increasing temperature during hot air drying. The total polyphenol and flavonoids contents were the highest in freeze-dried powder, at 9.3 and 6.2 mg/g, respectively. The levels increased as temperature increased in hot air drying. Anthocyanin content in freeze-dried powder was 8.51 mg/g, while it sharply decreased to 1.17~2.45 mg/g in hot-air drying. Vitamin C content in freeze drying ($979.4{\mu}g/g$) was higher than that in hot-air drying ($48.3{\sim}303.2{\mu}g/g$). The sample concentration required for 50% reduction of DPPH free radical scavenging ($RC_{50}$) was $79.7{\mu}g/mL$ in freeze drying, and showed high antioxidant activity. Also it decreased from $122.4{\mu}g/mL$ to $87.7{\mu}g/mL$ with temperature increase during hot air drying. We therefore conclude from the above results that freeze drying is more suitable for the production of blackberry powder, because this method showed high value of chromaticity, total polyphenol, flavonoid, anthocyanin content, vitamin C and antioxidant activity.

• 한국식품영양과학회지
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• 제39권9호
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• pp.1353-1358
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• 2010

폐자원으로써 버려지는 포도 가공부산물의 활용을 위한 기초연구로 본 연구에서는 포도부산물의 건조방법에 따른 일반성분, 색도, pH, 항산화성분 및 활성을 비교분석 하였다. 일반성분의 경우, 회분, 조지방, 조단백 함량은 열풍건조시료에서 더 높은 함량을 나타내었다. 색도 측정결과, L값(명도)과 a값(적색도)은 동결건조 한 시료가 더 높게 나타난 반면, b값(황색도)의 경우 열풍건조시료에서 높은 값을 나타내었다. pH는 열풍건조시료의 pH가 동결건조시료에 비해 약간 높은 값을 나타내었으나 큰 차이는 보이지 않았다. 총 폴리페놀 함량 및 안토시아닌 함량은 동결건조시료에서 더 높은 함량을 나타내었다. 항산화 활성 측정 결과 라디칼 소거능의 경우, DPPH 및 ABTS 라디칼 소거능이 열풍건조시료에 비해 동결건조시료에서 비교적 우수한 활성을 나타내었다. 반면, 환원력으로 측정한 항산화 활성의 경우, reducing power 및 FRAP 값이 동결건조시료에 비해 열풍건조시료에서 높은 활성을 나타내었으나 수치상으로 큰 차이를 보이지는 않았다. 이상의 결과에서 건조방법에 따른 항산화 성분과 항산화 활성을 비교한 결과 열풍건조시료에 비해 동결건조 시료가 더 우수한 것으로 사료된다.

• 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.

• 설비공학논문집
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• 제27권12호
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• pp.645-651
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• 2015

This paper presents an experimental study on the freeze drying process for poly ${\gamma}$ glutamic acid. The physical properties of poly ${\gamma}$ glutamic acid are measured during the freeze-drying process. The moisture contents of poly ${\gamma}$ glutamic acid according to the glass transient temperature are obtained by DSC (Differential Scanning Calorimetry) analysis. The end point of primary drying for the poly ${\gamma}$ glutamic acid with a thickness of 3 mm is obtained by measuring the thickness of the dried layer, the amount of moisture evaporation, the moisture content, and the pressure in the drying vacuum chamber during the freeze-drying process. By considering the variation in the glass transient temperature with respect to the moisture content of the material, a control schedule for the heating plate temperature is suggested during the secondary drying process.

• 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.

• 한국식품영양학회지
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• 제22권2호
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• pp.192-198
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• 2009

Cheongkukjang is a traditional fermented soybean food in Korea that is used in the manufacture of functional foods. This study was conducted to assess vitamin contents and sensory qualities of powdered Cheongkukjang dried by oven drying, far-infrared drying and freeze drying. Vitamins $B_1$, $B_2$, $B_6$, E, niacin and pantothenic acid were detected using all drying methods. However, vitamin D was not detected in the oven drying samples, and was most prevalent($82.47{\mu}g$/100 g) in the far-infrared drying samples. The sensory characteristics included color, off flavor, salty taste, bitter taste, sweet taste, roasted taste and after-taste. Oven drying and freeze drying samples exhibited highest and lowest color scores(5.62 and 2.0, respectively). Oven drying samples also exhibited the highest roasted taste score(4.76), although not significantly different from far-infrared drying samples(4.0, p<0.05), while the score of freeze drying samples(2.38) was significantly different from the other methods(p<0.05). It is concluded that freeze drying is most suitable.