• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.23 no.5
• /
• pp.327-333
• /
• 2011

In the present work, a new freeze protection method has been proposed for a natural circulation system of solar water heater. Though electrothermal wire is popularly used for the purpose, there are freezing troubles by wire cut-off and shortage of excessive electric power consumption. In the experimental device, hot water in storage tank was used to heat the outlet pipe from the tank if the pipe surface temperature falls lower than a set point. The cold water pipe to the storage tank was installed to directly contact the hot water pipe surface temperature rose by transferred heat.

• Korean journal of food and cookery science
• /
• v.30 no.2
• /
• pp.119-128
• /
• 2014

The purpose of this study is to propose the optimum adding rate of freeze-drying beet leaf powder, which has antioxidant components, that have superior DPPH radical extinction effects, in the Sulgidduk, a representative of steamed rice cake, which improve its functionality. According to the measured results on moisture contents and pH levels of Sulgidduk, with added freeze-drying beet leaf powder, the moisture contents have been significantly declined with increasing rates of added beet leaf powder. The pH levels of sample groups are within the range of 6.26-6.13. From the chromatography of measured results, lightness and yellowness have declined and redness have increased along with increasing rates of added beat leaf powder. According to the texture of measured results, the hardness, and chewiness have declined by the increasing the rate of added beet leaf powder. For the storage period, hardness, and chewiness have been inclined, but cohesiveness declines, with increased the storage period, while there are no changes from elasticity. The DPPH contents of Sulgidduk, with added freeze-drying beet leaf powder, inclined by increasing the rates of added beet leaf powder. The sensory test results of color, aroma and fragrance incline with increasing rates of added beet leaf powder. From acceptance test results, the sample group added with 3% receive the highest appraisals.

• Journal of Power System Engineering
• /
• v.15 no.4
• /
• pp.5-10
• /
• 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.

• Fisheries and Aquatic Sciences
• /
• v.17 no.3
• /
• pp.291-298
• /
• 2014

We investigate the effects of cryoprotectant mixtures on the quality of sand lance surimi (SLS) during storage at $-30^{\circ}C$. We monitored freeze-induced denaturation of myofibrillar protein in SLS and examined the texture profile of SLS gel. Freeze-induced denaturation was assessed by evaluating SLS $Ca^{+2}$-ATPase activity. SLS gels prepared with sorbitol or sucrose and a mixture of both as cryoprotectant. Higher concentrations of cryoprotectants resulted in significantly higher residual SLS $Ca^{+2}$-ATPase activity at the same storage time (P < 0.05). Residual $Ca^{2+}$-ATPase activity of SLS prepared with sorbitol was higher than that of sucrose when cryoprotectant concentration and storage period were same. A blend of sorbitol and sucrose resulted in a stronger cryoprptective effect of SLS myofibrillar protein than did sorbitol or sucrose alone. The presence of a phosphate compound in SOP (3% sorbitol + 0.2% phosphate compound) resulted in higher SLS $Ca^{2+}$-ATPase activity than that of did 5% sorbitol. The hardness, brittleness, and elasticity values and a folding test of the SLS gels were significantly affected by cryoprotectant concentrations and the storage time. Preference scores and acceptance for texture in a sensory evaluation of the SLS gels increased with increasing sorbitol or sucrose concentration.

• Food Science and Biotechnology
• /
• v.16 no.2
• /
• pp.187-192
• /
• 2007

The objectives of this study were to examine changes in the color and antioxidant compounds of paprika powder under various conditions, as well as to establish the suitable conditions for drying and storage. Paprika was dried using the following methods: freeze-drying, vacuum drying, far infrared-ray drying, and hot-air drying. Measurements of the moisture content, color pigments, and antioxidant compounds (total carotenoids, capsanthin, ascorbic acid, and total polyphenols) were completed during 120 days of storage at 4 and $30^{\circ}C$. We found that drying methods, storage temperatures, and packaging materials affected the American Spice Trade Association (ASTA) and Hunter color values, as well as the antioxidant content of paprika powder. There was a high correlation (r=0.87, p<0.01) between the ASTA color and the $a^*/b^*$ value. The loss of red color was closely related to the reduction of moisture content (r=0.81, p<0.01) during storage. Drying paprika with a low temperature in the absence of air resulted in better retention of the carotenoids and ascorbic acid. Also, as the retention of the carotenoids and ascorbic acid increased, the stability of the red pigment increased. Freeze-drying was found to be the most suitable drying method for the stability of the antioxidant compounds and red pigment.

• Food Science and Preservation
• /
• v.23 no.2
• /
• pp.145-154
• /
• 2016

This study investigated the possibility of usage of freeze-dried ingredients for the preparation of Nabak kimchi. The quality characteristics of Nabak kimchi using freeze-dried ingredients (radish, kimchi cabbage, green onion, garlic and ginger) were monitored during storage at $4^{\circ}C$. The initial pH of Nabak kimchi was 5.76~5.93, however, it decreased significantly over increasing storage periods (p<0.05). The titratable acidity of Nabak kimchi increased during storage, reaching 0.43~1.08%. Among the freeze-dried samples, those treated with freeze-dried radish and minor ingredients showed lower titratable acidity than that of the control. The initial number of total aerobic and lactic acid bacteria were 5.57~6.25, and 5.52~6.24 log CFU/g, respectively. After 28 days, the population of total aerobic and lactic acid bacteria in the raw ingredients and freeze-dried minor ingredients was less than 8.0 log CFU/g, but more than 9.0 log CFU/g in other samples. Yeasts and molds in Nabak kimchi were detected up to 2~3 log CFU/g, but coliforms were not detected in all samples during storage. The score of firmness and overall acceptability in the control, raw ingredients and freeze-dried minor ingredients were significantly higher than others (p<0.05). These results indicated that freeze-dried ingredients, such as green onion, garlic, and ginger, can be used in kimchi and would delay microbial growth and extend the shelf-life of kimchi without any deduction of sensory quality.

• The Korean Journal of Pesticide Science
• /
• v.12 no.4
• /
• pp.368-374
• /
• 2008

Dry formulation is a limiting step for successful development of microbial bio-pesticides with the antagonistic Gram-negative bacteria because their survival rates are too low during drying and storage. The high concentration of sodium chloride (NaCl) in culture medium that induces osmolyte in bacterial cells is known to increase of survival rate during drying in many Gram-negative bacteria. Effect of NaCl on survival of antagonistic non-pathogenic Erwinia carotovora subsp. carotovora 9-3 (Ecc 9-3) during drying and storage was studied. Growth rate of Ecc 9-3 was not much different up to 0.5 M NaCl in NB while it was lower significantly with 0.7 M NaCl. Survival rates were twice and 3 times higher with 0.5 M NaCl than with no additional NaCl during drying at room temperature and freeze-drying, respectively. Survival rate was also higher with high NaCl in culture medium during storage after drying. It was not much different on storage at $4^{\circ}C$ both of drying at room temperature and freeze-drying. However, the survival rate was higher on storage at $27^{\circ}C$ and $37^{\circ}C$ with high NaCl concentration. Among the additives tested, lactose affects most to survival rate both of drying at room temperature and freeze-drying, and dextrin influenced significantly to survival rate of drying at room temperature.

• Preventive Nutrition and Food Science
• /
• v.12 no.1
• /
• pp.40-45
• /
• 2007

The effects of drying methods on the physicochemical properties of chaga (Inonotus obliquus) mushroom powder were investigated. Scanning electron micrograph revealed that freeze drying produced smaller particle- sized samples which in turn resulted in higher porosity than did vacuum and hot-air drying. Samples prepared by freeze drying showed a significantly higher L*-value as compared with those prepared by hot-air drying and vacuum drying (p<0.05). The lightness (L*-value) significantly decreased with increasing relative humidity and storage temperature regardless of drying method (p<0.05). The yellowness (b*-value) increased significantly with increasing relative humidity (p<0.05). Browning index was significantly lower in samples prepared by freeze drying (p<0.05) but not significantly different between samples dried by hot-air and vacuum drying. Freeze dried sample exhibited a significantly higher degree of rehydration than other samples (p<0.05) probably due to the small particle size. Water solubility of the freeze dried sample was higher than those of the other methods while swelling ratio of the same sample appeared to be lower than those of others. Freeze dried chaga mushroom powder contained significantly lower amount of total phenolics and total sugar as compared to other samples (p<0.05).

• Journal of the Korean Solar Energy Society
• /
• v.31 no.5
• /
• pp.41-46
• /
• 2011

In the present work, a new freeze protection method has been proposed for a natural circulation system of solar water heater. Though electrothermal wire is popularly used for the purpose, there are freezing troubles by wire cut-off and excessive electric power consumption. In the experimental device, hot water in a storage tank was circulated by a small pump and used to heat the outdoor pipes if the cold water pipe surface temperature falls lower than a set point. As a result, It was observed that there was no hot water waste while the solar water heating system operated without freeze and burst.

• Journal of Embryo Transfer
• /
• v.29 no.1
• /
• pp.51-57
• /
• 2014

The objectives of this study were to investigate the effects of trehalose as a cryoprotectant for porcine freeze-dried spermatozoa, to find the optimal freeze-drying time and storage periods of freeze-dried spermatozoa, and to find out pronuclear formation rates, cleaved rates, and embryo development through intracytoplasmic injection of freeze-dried spermatozoa on porcine oocytes. The survival rates of spermatozoa after freeze-drying with trehalose treatment were significantly higher than those of them without trehalose treatment (p<0.05). The highest survival rates were found at 75 mM trehalose treatment. The longer storage periods after freeze-drying seemed to have a lower survival rates. Development in culture of pig by ICSI with trehalose treatment were significantly higher than those of them without trehalose treatment (p<0.05). Shorter freeze-drying time of spermatozoa was resulted in the highest cleaved rates and embryo development.