• Title/Summary/Keyword: freeze-drying

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Comparison of Vitamin Contents and Organoleptic Characteristics in Powdered Cheongkukjang Dried by Different Drying Methods (건조방법에 따른 분말 청국장의 비타민 함량과 관능적 특성의 비교)

  • Yang, Hak-Ryul;Park, Sang-Soon;Lee, Jang-Woo;Lee, Keun-Bo;Han, Myung-Kyu
    • The Korean Journal of Food And Nutrition
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    • v.22 no.2
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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.

Drying of Citron Juice from By-product of Citron Tea Manufacturing (유자차 부산물인 유자즙의 분말화 연구)

  • 남혜원;현영희
    • The Korean Journal of Food And Nutrition
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    • v.16 no.4
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    • pp.334-339
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    • 2003
  • To increase the utilization of citron, citron juice that is by-product of citron tea was spray dried and freeze dried. Cyclodextrin(CD) was used as wall material to stabilize during drying. The physiochemical properties of citron juice were as follows: water content of 82.3%, pH of 2.45, and there were little different in two kinds of drying or CD added in different ratio. Citric acid, malic acid, succinic acid and lactic acid were detected in all of the samples. Spray and freeze-drying increased markedly yellowness compared to that of citron juice. Heat stability was reduced by both of two kinds of drying, and CD 15% was more decreased than CD 10%. Water uptake by freeze-drying was somewhat higher than that of spray-drying. When sensory properties of original citron juice was compared with those of spray and freeze dried, freeze drying with 10% of cyclodextrin was evaluated as superior to citron juice or other drying conditions.

Effects of Rehydration Methods on viability after Freeze-drying of Streptomyces aureofaciens (Streptomyces aureofaciens 동결건조후 재수화 방법이 생존도에 미치는 영향)

  • Lee, Hyean-Woo;Yi, Dong-Heui;Lee, No-Woon
    • Applied Biological Chemistry
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    • v.38 no.6
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    • pp.512-515
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    • 1995
  • In order to examine the effect of rehydration methods on viability after freeze-drying of Streptomyces aureofaciens, we labeled the DNA of S. aureofaciens with $^3H-adenine$. Extracellular radioactivity levels appeared to be high in the rehydrated solutions after freeze-drying than freezing-thawing. In effects of rehydration after freeze-drying, the viability of the cell appeared about 20% in case of with admitting air at single ampule, but that of which appeared about 91% in case of without admitting air at double ampule. Thus, S. aureofaciens cells were damaged during the process of rehydration after freeze-drying.

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Effect of Drying Methods on the Production of Graphenes Oxide Powder Prepared by Chemical Exfoliation (화학적 박리법으로 제조된 산화그래핀 분말의 건조방법에 따른 물성 비교)

  • Rho, Sangkyun;Noh, Kyung-Hun;Eom, Sung-Hun;Hur, Seung Hyun;Lim, Hyung Mi
    • Korean Journal of Materials Research
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    • v.23 no.10
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    • pp.592-598
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    • 2013
  • Graphene oxide powders prepared by two different drying processes, freeze drying and spray drying, were studied to compare the effect of the drying method on the physical properties of graphene oxide powder. The graphene oxide dispersion was prepared from graphite by chemical delamination with the aid of sulfuric acid and permanganic acid, and the dispersion was further washed and re-dispersed in a mixed solvent of water and isopropyl alcohol. A freeze drying method can feasibly minimize damage to the sample, but it requires a long process time. In contrast, spray drying is able to remove a solvent in a relatively short time, though this process requires exposure to a high temperature for a rapid evaporation of the solvent. The powders prepared by freeze drying and spray drying were characterized and compared by Raman spectroscopy, X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, and by an elemental analysis. The graphene oxide powders showed similar chemical compositions; however, the morphologies of the powders differed in that the graphene oxide prepared by spray drying had a winkled morphology and a higher apparent density compared to the powder prepared by freeze drying. The graphene oxide powders were reduced at $900^{\circ}C$ in an atmosphere of $N_2$. The effect of the drying process on the properties of the reduced graphene oxide was examined by SEM, TEM and Raman spectroscopy.

Effect of Ginseng Polysaccharide on the Stability of Lactic Acid Bacteria during Freeze-drying Process and Storage

  • Yang, Seung-Hyun;Seo, Sung-Hoon;Kim, Sang-Wook;Choi, Seung-Ki;Kim, Dong-Hyun
    • Archives of Pharmacal Research
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    • v.29 no.9
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    • pp.735-740
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    • 2006
  • Lactic acid bacteria (LAB) quickly attenuate or are killed during the freeze-drying process and storage. The effect of some natural polysaccharides, which are known as potent antitumor and immunomodulating substances, on the viability of the LAB, Lactobacillus acidophilus and Bifidobacterium breve, on freeze-drying and storage were investigated. Among the polysaccharides tested, red ginseng polysaccharide (RGP) and chitosan significantly inhibited the cell death of the LAB during freeze-drying, and fucoidan and RGP most potently protected the cell death of the LAB during storage. The stabilities of the LAB on the addition of RGP and fucoidan were comparable to that of skimmed milk. However, white ginseng polysaccharide (WGP) did not promote storage stability. When 5% skimmed milk/5% RGP treated LAB were freeze-dried and stored, their viabilities were found to be significantly higher those treated with 5% or 10% RGP. The stabilizing effect of 5% RGP/5% skimmed milk during LAB freeze-drying and storage stability was comparable to that of treatment with 10% skimmed milk. Based on these findings, we believe that RGP beneficially improves the stability of LAB during the freeze-dry process and storage.

Quality of Single-Harvested Red Peppers by Drying Methods (일시 수확한 고추의 건조방법별 품질)

  • Chung, Koo-Min;Hwang, Jae-Moon
    • Korean Journal of Food Science and Technology
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    • v.35 no.2
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    • pp.329-333
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    • 2003
  • Fruits of 'Manita', a red pepper cultivar, and 'HL', a cultivar bred for single-harvest, cultivated by direct sowing method were harvested simultaneously. The red fruits were freeze-, sun-, indoor-, hot-air $(65^{\circ}C)$, and excessive hot-air (50% longer time) dried. For Manita. ASTA values of freeze- and indoor-dried red pepper were the highest $(153.6{\sim}168.4)$, and those of sun- and hot air-dried ones were $119.2{\sim}131.5$. Excessive hot-air drying decreased the redness by about $9{\sim}15%$ compared to normal hot-air drying. For HL, ASTA values $(150.3{\sim}171.7)$ of indoor-dried red peppers were much higher than other dried peppers. Red pigment in HL was destroyed easily during sun drying, showing values of only $49.2{\sim}69.2$. By excessive hot-air drying, the redness did not decrease, compared to normal hot-air drying. The organic acid contents of both cultivars were higher in sun- and hot-air-dried ones than freeze- and indoor-dried ones. Copsaicinoid contents of both cultivars decreased up to 22% by excessive hot-air drying compared to normal hot-air drying. Sugar contents were lower in all drying methods other than freeze drying for both cultivars.

Characterization of Expanded Tobacco Lamina Tissues by Freeze Drying (냉동건조에 의한 잎담배 팽화특성)

  • 김병구
    • Journal of the Korean Society of Tobacco Science
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    • v.17 no.2
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    • pp.149-159
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    • 1995
  • The freeze drying rate was investigated under various conditions such as pressure and moisture contents in order to establish the optimum condition for expansion of the culled flue cured tobacco lamina. The optimal pressure in the chamber to maintain the heat and mass transfer was about 0.8torr, When the moisture contents of sample was 50-60%, expanding rate was the optimum condition and the rate was 67-76%. As the thickness of the sample layers was increased, drying-rate was decreased conversely and this result seemed to be due to decline of heat and mass transfer coefficients. Differences with the position of its stalk were also observed in drying rate, and low stalk position leaves of 5 and 3 was the fastest. Key words : freeze drying, Popping, expansion tobacco.

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Freeze Drying of Fermented Milk Prepared from Milk and Fruit Juices (유유와 과즙으로 만든 발효유의 동결건조)

  • Ko, Young-Tae;Oh, Mi-Hwa
    • Korean Journal of Food Science and Technology
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    • v.30 no.6
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    • pp.1448-1455
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    • 1998
  • Fermented milk was prepared from milk or mixture of milk and apple juice/grape juice, and it was freeze dried. pH change and growth of Lactobacillus acidophilus (KCTC 2182) during freeze drying were studied. The effects of freeze drying on sensory evaluation and volatile aroma compounds in freeze dried sample or reconstituted sample were also studied. Freezing and freeze drying did not affect pH of fermented milk. Number of viable cells of L. acidophilus was markedly reduced during freezing or freeze drying. When number of viable cells in original fermented milk was considered as 100%, survival ratio of viable cells after freezing was $64.5{\sim}85.2%$ and that after freeze drying was $10.0{\sim}21.1%$. When sensory properties of original fermented milk prepared from juice-milk (ratio 15:35) were compared with those of freeze dried/reconstituted sample, sensory properties of original sample were better than those of freeze dried/reconstituted sample. Ethanol, diacetyl, butanol and acetoin were detected in all of original samples and freeze dried/reconstituted samples while acetone was detected in samples containing high amount of grape juice. Volatile aroma compounds in original fermented milk were reduced during freeze drying. L. acidophilus produced ethanol, diacetyl and acetoin during fermentation.

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Prediction of Sublimation Drying Time for Carrot in Freeze-Drying (당근의 동결건조에서 승화건조시간 예측연구)

  • Park, Noh-Hyun;Kim, Byung-Sam;Bae, Sin-Chul
    • Korean Journal of Food Science and Technology
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    • v.25 no.4
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    • pp.313-320
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    • 1993
  • A sublimation model of the freeze drying process, which accounted for the removal of free water, was presented and used to study the operation conditions of freeze driers for carrot juice. It was found that the shortest drying time was obtained when the condenser temperature and chamber pressure were kept at heir lowest values and the plate temperature was controlled independently so that the scorch and melting constraints were both held throughout the drying period. The effect of sample thickness on the drying time was significant. Optimal policies were investigated experimentally in laboratory freeze dryer.

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A Study on the Changes in the Alliinase Activity during the Vacuum Freeze Drying of Onions(Allium cepa L.) (양파의 진공 동결 건조 과정 중 Alliinase 활성 변화에 관한 연구)

  • Chae, Soo-Kyu;Yun, Mi-Suk
    • Culinary science and hospitality research
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    • v.14 no.1
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    • pp.144-151
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    • 2008
  • This study investigated the changes in the contents of allicin and diallyl disulfide and in the alliinase activity during the vacuum freeze drying of onion samples treated as the whole, sliced and crushed forms. The contents of allicin and diallyl disulfide in raw onions were 26.40ppm and 2.78ppm respectively. The contents of allicin and diallyl disulfide of onion samples treated as the whole, sliced and crushed forms increased with the progress of vacuum freeze drying. The degree of increase was different in each onion sample form prepared by vacuum freeze drying(p<0.05). The specific activity of alliinase in raw onions was 7.536 units/mg protein. The activity in onion samples treated as the whole, sliced and crushed forms decreased with the progress of vacuum freeze drying. The activity in the whole onion prepared by the vacuum freeze drying for 8 hrs reduced to 5.516 units/mg protein with 73.2% remaining and to 3.304 units/mg protein with 43.8% remaining for 36 hrs. The activity in the sliced onion prepared by the vacuum freeze drying for 36 hrs reduced to 2.366 units/mg protein with 31.4% remaining and the activity in the crushed onion prepared by the vacuum freeze drying for 36 hrs reduced to 2.232 units/mg protein with 29.6% remaining. The alliinase in onion sample treated as the whole form showed the highest remaining activity during the vacuum freeze drying.

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