• Applied Biological Chemistry
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• v.39 no.5
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• pp.384-388
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• 1996

This research was conducted to investigate the effective methods for browning inhibition on yam (Dioscorea aimadeimo) during dehydration by physical and chemical pretreatments. Moisture, crude protein, crude fiber and N-free extract contents of yam were 81.17%, 1.43%, 0.29% and 15.81%, respectively. Yams were sliced to 0.5 cm thickness and placed to single and poly layer in plastic tray, and then changes of their weights were measured during air dehydration at $50^{\circ}C,\;65^{\circ}C,\;and\;80^{\circ}C$. The dehydration time reaching to optimum moisture level for the pulverization of the yam slices were 10, 6, 3 hours(single layered) and 12, 7, 5 hours(multi layered) at the respective temperature. To inhibit browning at $80^{\circ}C$ air dehydration, water and steam blanching, microwave treatment effects were investigated on yam slices for 30 sec. and 60 sec. Steam blanching for 30 sec. was comparatively effective to inhibit browning of yam slices. Yam slices were immersed in single and combined browning inhibitor solutions and evaluated for browing degree during dehydration by the values of Hunter L, a, b and ${\Delta}E$. The most effective pretreatment to inhibit browning of yam slices was immersion In the solution containing 500 ppm of citric acid and 1000 ppm of cysteine for 1 min.

• Journal of The Korean Society of Grassland and Forage Science
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• v.42 no.4
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• pp.258-263
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• 2022

This experiment was conducted to confirm the possibility of manufacturing artificial Italian ryegrass hay using far-infrared rays in Korea. The machine used in this experiment was a far-infrared ray dryer capable of adjusting temperature, airflow, and far-infrared radiation, and was conducted on Italian ryegrass harvested in May. Conditions for drying were performed by selecting a total of nine conditions, and each condition was set to emission rate of 42 to 45%, and the internal temperature was set to 65℃. The speed of the air flow in the machine was 40-60 m/s, and the overall drying time was 30 minutes for 42% radiation, 25 minutes for 43% radiation, and 20 minutes for 45% radiation. The final dry matter content according to each drying condition was 88.5% on average, and the dry matter content suitable for hay was shown in the all treatment. Looking at the power consumption according to the drying conditions, the lowest was found in the treatment that dried for 20 minutes at 45% radiation. In the drying rate, there was no difference in drying conditions 1 to 5, but a significantly low tendency was shown in conditions 6 to 7. In terms of feed value, CP and IVDMD were higher than raw materials in most drying conditions, and ADF and NDF contents were low, and tended to be high in drying conditions 4, 7, and 8. Through the above results, it was judged that drying conditions 7 and 8 were the most advantageous when considering drying speed, power consumption, and quality.

• Journal of the Korea Organic Resources Recycling Association
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• v.16 no.3
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• pp.29-37
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• 2008

The objective of this research is to evaluate the optimum treatment methods for disposal sludge cake at different temperatures and periods of time. The disposal dehydrated sewage cake used in this study was obtained from N wastewater treatment plant in the P City. This system consists of continuous conveyer thermal dryer and pyrolysis. The continual conveyer thermal dryer was operated to evaluate the optimum conditions with temperature settings, ranges from 130 to $180^{\circ}C$, loading rates of 650~750 kg/hr and operating times of 110~120 minutes. The continual pyrolysis was also operated to evaluate the optimum conditions with temperature settings, ranges from 650 to $750^{\circ}C$, loading rates of 100~158 kg/hr and operating times of 20~40 minutes. The sewage sludge cake has a moisture content of 78~80% (wt) which decreased up to 1~3%(wt) resulted in breaking of cell wall after operating the continuous conveyer thermal dryer and pyrolysis. Important parameters which were operating times, moisture contents, loading rates, conveyer velocities and rotary velocities effects on the thermal kinetics and dynamics were investigated to evaluate the optimum conditions for the continual thermal dryer and pyrolysis.

• Korean Journal of Food Science and Technology
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• v.31 no.3
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• pp.631-637
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• 1999

An investigation was carried out to study the effects of aging time, storage temperature, and drying type on the physical, chemical and sensory properties of Korean rice cake. Water content and cooking properties were significantly influenced by aging time and storage temperature. However, aging time did not affect the soup turbidity. Difference in water content was noticeable by drying type. The microwave treated rice cake (MW) showed a higher water content than the other ones. The lightness (L-value) was not affected by the aging time and drying type. Rice cake storaged at 4oC showed the highest L-value. The textural properties of rice cake were influenced by the all sources of variables. There was a significant difference in hardness between microwave and hot air treated rice cake (MWH), and microwave and vacuum treated rice cake (MWV). In the sensory properties, mean intensities of all attributes except chewiness were significantly different among drying types. The MWV showed a higher acceptability than the MW and the MWH. Scanning electron photomicrographs revealed that the MWV has more porous structure. The MWV was the most desirable one as determined by the physical, chemical and sensory evaluation.

• Korean Journal of Food Science and Technology
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• v.35 no.1
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• pp.84-91
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• 2003

The effects of different dehydration conditions for the removal of ginkgo nut inner coat on peeled ginkgo nuts were examined using physical and sensory methods. Dehydration of ginkgo nuts at $90^{\circ}C$ for 120 min resulted in greater hardness, lightness (L), redness (a), yellowness (b), and firmness. Higher roasted flavor and larger holes were observed with dehydration at $150^{\circ}C$ for 30 min and greater cooked ginkgo flavor and green color with dehydration at $120^{\circ}C$ for 50 min. Based on these findings, dehydration at $120^{\circ}C$ for 50 min was determined as the adequate hot air dehydration condition for the removal of ginkgo nut inner coat. Ginkgo nuts stored at $25^{\circ}C$ maintained overall desirability up to 4 weeks. In ginkgo nuts stored at $4^{\circ}C$, all sensory desirabilities evaluated were reasonably high until 60 days of storage; desirability of appearance decreased moderately at 80 days of storage, and appearance became very undesirable at 180 days. Ginkgo nuts stored at $-18^{\circ}C$ showed little changes until 10 months of storage, but slight decreases in overall desirability, flavor, and texture were noted at 12 months.

• Journal of the Korean Geotechnical Society
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• v.29 no.10
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• pp.29-37
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• 2013

Organic soils are widely distributed at Youngdong areas in Kangwon prefecture and Jeonbuk area. Such organic soils usually consist of undecomposed fiber materials. It is difficult to exactly measure the water content of such organic soils because some organic materials may decompose at $110^{\circ}C$ in drying oven. In this study, both drying oven and microwave oven methods are used to measure the water content of organic soils. Three different levels of oven temperature, $60^{\circ}C$, $80^{\circ}C$, and the standard temperature of $110^{\circ}C$, were used to measure the water content of organic soils in the 1st, 2nd, and 3rd day. The water content by microwave oven was measured for two different sample masses (30, 60 g) with five different measuring times (3, 6, 9, 12, 15 min.). As the temperature increased, the water content of organic soils increased due to the decomposition of organic materials in soils. The water content of some soils increased up to 2 times as the temperature was increased from $60^{\circ}C$ to $110^{\circ}C$. However, the water content was not changed after the 1st day, regardless of drying oven temperature and soil types. The water content by microwave oven became constant after 12 min. for the 30 g sample and 15 min. for the 60 g sample used. The measured water content by microwave oven was similar to that measured by drying oven at $60^{\circ}C$.

• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.1
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• pp.97-102
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• 2000

This study was carried out to investigate the effects of operating temperatures on decomposition and physicho-chemical properties of household food wastes in a fermentation dryer, which was manufactured by Samwoo Co. Ltd. The household food wastes of 100 kg can be put and dried in this dryer at once. The experiments were performed at each temperature of $35^{\circ}C$, $45^{\circ}C$, $55^{\circ}C$ and $70^{\circ}C$ for two days respectively. The samples taken at the fixed time were dried at $105^{\circ}C$ and analyzed to find the decomposition rate and the concentration of each substance. The results obtained were as follows: The decomposition rate at 35 and $70^{\circ}C$ was the highest and showed the similar tendency during the experimental period. The higher the operating temperature was, the faster the water content of the composting material reduced. pH value increased at the operating temperature of 55 and $70^{\circ}C$ and was higher than at the other operating temperatures. Nitrogen content did not show any tendency during the experimental period. $P_2O_5$ and CaO content increased during the experimental period but MgO, $K_2O$ and NaCl were not accumulated. Cu content based on dry matter was in the range of ND~100.4 mg/kg and Cd, Pb and Cr were not detected.

• Korean Journal of Food Science and Technology
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• v.30 no.2
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• pp.348-355
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• 1998

The developments of various processed foods and the high quality dried fruits, in particular, are urgently needed for the enhancement of fruit consumption and their competitive values. Therefore, in this study, three variables by three level factorial design and response surface methodology were used to determine optimum conditions for osmotic dehydration of kiwifruit. The relationships of moisture losses, solid gains, weight reductions, sugar contents, titratable acidities and vitamin C contents depending on changes with temperature, sugar concentration and immersion time were investigated. The moisture loss, solid gain, weight reduction and reduction of moisture content after osmotic dehydration were increased as temperature, sugar concentration and immersion time increased. The effect of concentration was more significant than those of temperature and time on mass transfer. Sugar content was increased by increasing sugar concentration, temperature, immersion time during osmotic dehydration. Titratable acidity and vitamin C content were increased by decreasing temperature, immersion time and increasing concentration during osmotic dehydration. The regression models showed a significant lack of fit (P>0.05) and were highly significant with satisfying values of $R^2$. At the given conditions such as $66{\sim}69%$ moisture content, above $24^{\circ}Brix$ sugar content and more than 23 mg% vitamin C, the optimum condition for osmotic dehydration was $37^{\circ}C,\;55^{\circ}Brix$ and 1.5 hour.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.11a
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• pp.60-60
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• 2011

염색폐수의 정화에는 필연적으로 다량의 슬러지 폐기물이 발생한다. 염색폐수 슬러지는 그간 인근 공해 해상에 투기하는 해양 배출로 저렴하게 처리하였으나, 해양오염을 우려하는 국제협약(1972년 런던협약, 1996년 교토의정서)에 의하여 2008년 8월부터 배출기준이 강화되고 2012년 2월부터는 해양배출이 금지 될 예정이다. 염색폐수 슬러지의 해양 배출이 금지되면 대체 처리방법으로는 지정매립장을 통한 매립처리 방법이나 고온 소각시설에서의 소각처리 방법이 거론되고 있다. 그러나 매립처리는 슬러지 내 함유 수분으로 인한 침출수의 문제와 더불어 장기간 안정적으로 저렴하게 사용할 수 있는 대규모 처분장을 확보하기 어려운 실정이며 소각처리는 슬러지의 높은 함수율로 인해 소각 시보조 연료의 투입이 필연적으로 최근 원유가 급등 등 에너지 비용이 지속적으로 상승함을 고려할 때 소각처리비용 또한 상당한 고가가 될 것으로 예측된다. 이와 같이 슬러지 해양배출이 금지되면 섬유 염색업체들은 많은 환경비용 부담을 안을 것이다. 본 연구에서는 대규모 염색산업단지 공동폐수처리장에서 발생하는 염색폐수 슬러지의 효율적인 건조를 위해 산업단지 내의 열병합발전소에서 발생하는 보일러 폐열을 이용하였으며, 조건 특성 및 효율을 파악하기 위해 보일러 폐열의 특성을 고려하여 슬러지 두께 및 체류시간 등 건조공정 운영조건에 따른 변수별 연구를 수행하였다. 열병합발전소 보일러에서 배출되는 폐열은 온도가 $150^{\circ}C$ 정도로 기존의 슬러지 건조에서는 사용되는 $700^{\circ}C$에 비해서는 매우 저온이다. 하지만 보일러 배가스의 경우, 온도에 비해 많은 풍량을 가지고 있으므로 열량으로 환산시 충분히 가치가 있는 것으로 조사되었다. 염색폐수 슬러지의 경우, 함수율 70% 이내의 탈수 Cake 형태이므로 두께가 두꺼울수록 건조효율이 감소하였으며, 체류시간이 길어질수록 건조효율은 증가하나 20mm 이상에서는 건조효율이 급격히감소하였다. 이를 바탕으로 5톤/일 규모 슬러지 건조 Pilot Plant를 제작하여 운영하였는데, 염색폐수슬러지의 투입공정에서 슬러지와 열풍의 접촉면적을 넓혀 건조효율을 높이기 위하여 슬러지를 압출노즐을 이용하여 슬라이스 칩 형태로 제조하여 건조공정에 투입하였으며, 건조실 내에서도 건조효율의 상승을 위하여 내부열풍순환팬을 설치하여 운영하였다. Pilot 운영결과, 체류시간 52분에서 슬러지의 함수율은 70%에서 10%이하로 감소하였다.

• Applied Biological Chemistry
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• v.32 no.4
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• pp.332-337
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• 1989

Rheological properties of rehydrated freeze dried instant rice were investigated in comparison with that of cooked rice. The time changes in reciprocal hardness of instant rice grains at various rehydration temperatures$(60{\sim}90^{\circ}C)$ could be expressed by the first order reaction rate equation regardless of rehydration temperature and reaction rate constant increased as the rehydration temperature increased. Activation energy for rehydrating instant rice was 6.1 kcal/g-mol. Analysis of compressive stress relaxation test showed that the viscoelastic properties of both rehydrated instant rice and cooked rice grains could be expressed by 6-elements generalized Maxwell model. Rehydrated instant rice revealed higher relaxation decay than that of cooked rice and showed the elastic property increased by increasing the rehydration temperature.