• Korean Journal of Food Science and Technology
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• v.29 no.1
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• pp.9-14
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• 1997

The effect of freezing, thawing and blanching on the change of extractable pigment content of purple sweet potato (PSP) was investigated. Freezing at $-5^{\circ}C$ was more effective than freezing at $-20^{\circ}C\;or\;-40^{\circ}C$, and rapid thawing methods such as microwave heating or hat air blast heating were effective than slow thawing methods such as thawing at $4^{\circ}C\;or\;20^{\circ}C$. Inactivation of enzymes, which cause pigment destruction during thawing, by blanching before freezing was necessary to obtain the highest possible amount of extractable pigment from PSP. Microwave blanching for $3{\sim}4$ min or hot air blanching for $10{\sim}15$ min were effective in extracting pigment from PSP.

• Microbiology and Biotechnology Letters
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• v.26 no.3
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• pp.200-205
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• 1998

A probiotic-strain of Lactobacillus sp. was cultured in bovine blood plasma-based (BBPB) medium and freeze-dried to prepare a probiotic product as an animal feed additive. The cell mass produced in the medium, $5.2{\times}10^9$ CFU/ml, was high enough to be commercialized and was 74% of that in MRS medium. The survival rate of tactobacillus sp. against freeze-drying was affected by the conditions for treatment of cultured BBPB broth before freeze-drying such as pH adjustment, volume reduction and freezing rate. It was also found that the blood protein hydrolysate remaining in broth also enhanced the survival rate. Among various protective substances, sucrose showed a high stabilizing effect with 10% (w/v) addition, by which the maximum survival rate (48.3%) and viable cell count ($3.0{\times}10^{10}$ CFU/g) were obtained.

• Korean Journal of Animal Reproduction
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• v.13 no.3
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• pp.141-148
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• 1989

The effects of seeding method and optimum time for freezing embryos according to the developmental stages on embryo survival rates after rapid freezing were determined using the FDA-test. The summarized results are as follows : 1. In the rapid freezing of embryos, the sucrose added medium together with Co-seeding or non-seeding showed the FDA scores of 4.67 and 4.20, respectively, but, raffinose addition obtained FDA scores of 4.27 and 3.97. 2. The developmental stage of embryos at freezing was most critical on the survival of embryos after thawing. Higher FDA scores were obtained in the order of blastocyst stage(4.94), morula stage(3.82) and ealy stage(2.65) in sucrose added medium. The same trend was observed in the raffinose added medium with an order or 4.91, 4.47 and 2.32. 3. Microscopic study of embryo before freezing and post-thawing indicated that the embryo showed shrinkage within 5 minutes after the embryo was transfer to the freezing medium. When thawed embryo was tranfered to the dilution medium, swelling of the embryo was observed and there after it reshrank indicating the removal of cryoprotectant from the embryo. The size of the embryo recovered to the original state when it was moved into a PBS-solution.

• Korean Journal of Agricultural Science
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• v.22 no.1
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• pp.62-68
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• 1995

This study was carried out to examine splitting, developmental capacity and rapid freezing of blastomeres separated from 2-, 4-, 8-cell and morula from porcine embryos. The results obtained in this study were summerized as follows : 1. The successful splitting rate by pronase was 85.7% in 2-cell embryos(average splitting rate, 68.0%), and by manipulator was 76.6% and 74.3% in 2- and 4-cell embryos. 2. The developmental capacity rates of splitted embryos by the pronase treatment were 24.1%, 20.4%. 25.5% and 26.6% in 2-, 4-, 8-cell and morula, and by manipulator were 36.4%, 39.5%, 36.1% and 41.9%, respectively. 3. The successful results of in vitro culture after frozen-thawed of splitted embryos were 16.1%(glycerol) in 2-cell, 16.7%(DMSO) in 4-cell and 27.6%(ethyleneglycol) in morula, respectively.

• Korean Journal of Food Science and Technology
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• v.31 no.1
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• pp.54-61
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• 1999

A study was conducted to find a rapid thawing method which prevents excessive drip loss and local overheating. Effects of thawing methods (conventional thawing vs. 2,450 and 915 MHz microwave thawing) on thawing time, temperature profile, drip loss, water holding capacity, total color difference and total aerobes were investigated. Samples were thawed at 4, 28 and $50^{\circ}C$ in a refrigerator or an oven for the conventional thawing methods the convertional thawing methods. Power levels of 5, 10 and 15 kW were used for 915MHz microwave thawing. Cotreatment of 915 MHz microwave and convectional heating $(120^{\circ}C)$ was tested. 915 MHz microwave accelerated the thawing rate, and showed significant effects on penetration depth, drip loss, water holding capacity and total aerobes. Cotreatment of 915 MHz microwave and convection heating was appeared to be a suitable thawing process for the food industry.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.3
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• pp.342-347
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• 2007

Physicochemical properties of onion powder as influenced by drying methods were investigated. Moisture contents of onion powder were 13.29%, 12.99%, and 10.78% for samples dried using hot-air dryer, freeze dryer, and vacuum dryer, respectively. There were no significant differences in crude fat, crude protein, and crude ash content (p>0.05) depending on the drying methods. Samples prepared by freeze drying showed a significantly higher L-value as compared with those prepared by hot-air and vacuum drying (p<0.05). Scanning electron micrographs showed that freeze drying produced smaller particle-sized sample which in turn resulted in the higher porosity of the sample. Freeze dried samples revealed significantly lower degree of rehydration than other samples (p<0.05) probably due to small particle size of the sample. Water solubility of freeze dried sample appeared to be higher than that of other drying methods while the swelling ratio of the same sample appeared to be lower than that of the others. 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. Vitamin C content was higher in freeze dried onion powder due to the lower temperature applied to the sample. Freeze dried onion powder contained significantly lower amount of total polyphenol and higher amount of total sugar as compared to other samples (p<0.05).

• Korean Journal of Food Science and Technology
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• v.31 no.3
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• pp.682-687
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• 1999

The destruction of tissues by volume increase at food freezing is accepted as one of the factor responsible for quality damage. For this reason, the internal pressure developed in meats were investigated with a pressure transducer during freezing, frozen storage and thawing. Increasement of 6.33% for volume and $942.17\;kg/cm^2$ for density at $-20^{\circ}C$ for beef were shown. In quick and slow freezing of beef, internal pressure reached to highest point after reached to the lowest point at initial of the zone of ice crystal formation. The internal pressure was approximately $8{\sim}10\;psig$ and pressure difference was about 1 psig, which was bigger in immersion freezing than that of still-air freezing. During frozen storage of pork, internal pressure of $1.84{\sim}2.32\;psig$ occurred repeatedly as a function of sample weight at material temperature difference of ${\pm}1^{\circ}C$. The internal pressure during thawing of pork was decreased slowly after rapid increase to the maximum for less than 5min at the beginning of thawing. Internal pressure value at thawing was higher than that at freezing in most cases. Internal pressure of beef with thermal equalized freezing was about $1{\sim}4\;psig$, which was lower than that of non-thermal equalized freezing. Also, freezing time was shortened to $10{\sim}20%$.

• Korean Journal of Food Science and Technology
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• v.31 no.3
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• pp.688-696
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• 1999

Changes in quality during frozen storage of meat with thermal equalized freezing and various freezing methods were investigated. When beef were frozen at freezing rate of $0.39{\sim}0.66\;cm/h$, average diameter of ice crystal were about $30{\sim}50\;{\mu}m$ and showed broken tissues or irregular cracks. At freezing velocity of $1.14{\sim}2.26\;cm/h$, ice crystals of about $10{\sim}30\;{\mu}m$ was formed mainly inside or between fiber and slight destruction of tissues was occurred. The average diameter (D) of the ice crystals were related to the characteristic freezing time $(t_c)$ by the equation: $D({\mu}m)=4.089+26.88logt_c\;(r^2=0.913)$. Beef with still-air freezing showed higher drip loss than methods of immersion and thermal equalized freezing. Also, drip loss of pork was relatively lower than beef and showed highest value to 7.39% during storage on 40 days at air-blast freezing method. No apparent change of pH during storage of frozen beef and pork by freezing methods were detected. However, least changes for sample with thermal equalized freezing was found compare to sample with still-air and air blast freezing in VBN and TBA value. The fluctuation of frozen storage temperature did not cause noticeable changes on pH and water content. However, drip loss, VBN and TBA values were increased slowly as frequency of fluctuation increased.

• Proceedings of the KSAR Conference
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• 2002.06a
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• pp.31-31
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• 2002

건강보조식품의 홍수와 함께 우유보다 소화흡수가 좋고 건강식을 즐겨하는 현대인들의 취향에 발맞추어 상대적으로 유량과 산육성이 좋은 외래산양의 유입이 급속하게 늘어남으로써, 일부 재래산양 사양 농가들은 생산성 향상을 목적으로 재래산양과 외래산양의 무분별한 교배를 시키므로써 재래산양의 유전자원의 보존문제가 대두됨과 동시에 재래산양의 개량의가속화, 근친교배에 따른 문제점, 계절번식에 따른 산자생산의 한계 등은 재래산양의 인공수정에 대한 깊이 있는 연구로 이어져야 하겠기에 본 연구에서는 38 두의 재래산양을 공시하여 실험한 결과 여름과 겨울에 채정한 정액보다는 봄가을에 채정한 정액의 량이 2.0㎖로 여름과 겨울보다 많았으며, 정자농도는 봄에 21.0×10/sup 8//㎖로 가장 짙었고, 총정자수는 봄에 42.0×10/sup 8/로 가장 많았으며, 운동성은 가을에 90(motility)로 가장 좋았다. (중략)

• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.6
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• pp.529-537
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• 1985

The present study was carried out to investigate the effect of the partial freezing as a means of keeping freshness of mullet (Mugil cephlus). Living samples were killed and stored by icing, partial freezing at $-3^{\circ}C$ and freezing at $-30^{\circ}C$, respectively, Changes in the freshness of the mullet muscle and the phys cal properties of its meat paste product were examined during storage. The results obtained are summarized as follows: The period that k value reached to $20\%$ during storage was the longest in the frozen storage, followed by the partial frozen storage and the ice storage, which was 4 days in the mullet muscle stored by partial freezing. In the case of VBN content, it was below 20 mg/100g in the mullet muscle stored by icing and partial freezing. The oxidation of lipids in the mullet muscle was greater in the ice storage than in the partial frozen storage. The myofibrillar protein of the mullet muscle was appeared to decrease during storage, which the decreasing ratios during storage for 9 days were below $3\%$ in the frozen storage, $17\%$ in the ice storage and $10\%$ in the partial frozen storage. While, the alkali-soluble protein showed to increase and in non-protein nitrgenous compounds, sarcoplasmic protein and stroma was not a great change during storage. The decrease of gel strength, folding strength and texture of meat paste products prepared under different storage conditions was the greatest in the ice storage, the next in the partial frozen storage and such changes in the frozen storage were not so much. In gel strength of the product prepared with sample fishes stored for 10 days, the gel strength in the ice storage, partial frozen storage and frozen storage was about $30\%,\;60\%\;and\;97\%$ of the control. respectively. The expressible drip of the products increased with storage time of raw fishes, which that of the products prepared with sample fishes stored for 15 days was about 2.1 times in the ics storage, about 1.5 times in the partial frozen storage and about 1.1 times in frozen storage as much as that of the control, respectively.