• Korean Journal of Food Science and Technology
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• v.28 no.6
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• pp.1164-1170
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• 1996

Studies were carried out to investigate the changes of constituent components in chestnuts (Castanea crenata Sieb. et Zucc) during storage at $20^{\circ}C$ for 9 weeks and $1^{\circ}C$ for 15 weeks. Ascorbic acid content of chestnut was 4.08 mg% in oxidized form and 17.7 mg% in reduced form which was 81.3% of total ascorbic acid. The reduced form gradually decreased during storage, while the oxidized forms increased during 5 weeks at $20^{\circ}C$ and 7 weeks at $1^{\circ}C$. The major organic acids in chestnut were malic acid, citric acid and quinic acid. Citric acid significantly decreased during storage, while malic acid increased during storage at $20^{\circ}C$ and decreased at $1^{\circ}C$. Free sugars in chestnuts were identified as glucose, fructose, sucrose and maltose. Glucose and fructose decreased after 5 weeks storage at $20^{\circ}C$ followed by an increase thereafter. Sucrose and maltose also increased. The major free amino acids in the chestnut were glutamic acid, aspartic acid, arginine, alanine, proline and serine. Glutamic acid, arginine, alanine, threonine, phenylalanine, valine and lysine increased during storage at $20^{\circ}C$, while proline, serine, isoleucine. leucine and ${\gamma}-aminobutyric$ acid decreased.

• Korean Journal of Food Science and Technology
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• v.30 no.3
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• pp.562-568
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• 1998

Rice (Dongjin-byeo) added with black rices (Chindo and Suwon-415) was cooked and the changes of texture and color of this cooked rice were investigated by texture analyser and color & color difference meter. The hydration time to come to the equilibrium condition was at least 11 hr in black rices. The optimum ratio of water to cooked rice added with black rice was 1.6 (ratio of water to rice) and the hardness of cooked rice added with 5% Chindo black rice was $5.66\;kg_f$. Regardless of ratio of water to rice, Hunter a value increased as the ratio of black rice addition to rice increased, while L value decreased. The color elution rate of Suwon 415 was 4 times greater than that of Chindo black rice. The pH of the steep water of Suwon 415 at $20^{\circ}C$ during 120 min decreased from pH 6.40 to pH 6.16 as the steeping time increased. The optimum heating time by microwave oven of cooked rice added with black rice was between $90{\sim}120\;sec$ to recover the original texture after cold storage treatment of 7 days.

• Food Science and Preservation
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• v.15 no.3
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• pp.377-384
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• 2008

The gamma irradiation process was performed to prolong a shelf-life of peaches and the effects of a gamma irradiation on the nutritional, physiochemical and sensory characteristics of peaches were evaluated during a post-irradiation storage at $4^{\circ}C$ and $25^{\circ}C$. Nutritional, physiochemical and sensory characteristics of peaches were stable at 1 kGy of an irradiation, a recommended dose for fruits and vegetables by CODEX, and the viable cell counts of contaminated microorganisms were reduced by 2 decimal reduction, at this dose. After a 1-week storage at ambient condition, the microbiological quality of the 1 kGy irradiated peach was stable, while all the non-irradiated peaches were deteriorated Furthermore, cold storage enhanced the shelf-life of the gamma irradiated peach and the nutritional and physiochemical characteristics of the peaches were comparatively stable up to 6 weeks. Right after gamma irradiation, the sensory evaluation results were not different in any of the samples, and the sensory quality of the irradiated peaches was adequate for a 4-week storage at $4^{\circ}C$. Our results suggested that gamma irradiation at 1 kGy can be used to enhance the shelf-life of peach without a significant loss in the quality attributes, especially upon cold storage after radiation treatment.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1996.06b
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• pp.311-352
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• 1996

Peltier 효과를 이용한 열전소자는 열응담 감도가 좋고 선택적 냉각이 가능하며 무소음, 무진동 및 소형화의 장점으로 각종 전자부품의 국부냉각소자로 응용되고 있다. 또한 최근 냉매의 사용없이 냉각이 가능한 열전재료를 이용한 자동차나 가정용 에어컨 및 냉장고 등의 각종 냉방시스템의 개발도 크게 주목을 받고 있다. 기존의 Bi2Te3계 단결정 열전재료는 성능지수는 우수하나, 기계적 취약성에 기인하여 소자가공시 수율 저하가 가장 큰 문제점으로 지적되고 있다. 이와 같은 문제점을 해결하기 위해 최근 단결정에 비해 기계적 강도가 우수한 다결정 열전재료의 제조공정에 관한 연구가 활발히 이루어지고 있으며, 그 일환으로 기계적 합금화법을 이용한 열전재료의 제조공정이 연구되고 있다. 원료금속이 고 에너지 볼-밀 내에서의 연쇄적인 파괴와 압접에 의해 합금분말로 변화되는 기계적 합금화 공정은 상온공정으로 이를 사용하여 다결정 열전재료를 제조시 기존의 다결정 열전재료의 제조공정인 "용해 및 분쇄법'과 비교하여 제조단가를 낮출 수 있는 장점이 있다. 본 연구에서는 전자냉각소자용 열전재료로서 상온부근에서 성능지수가 가장 우수한 p형 (Bi,Sb)2Te3 및 n형 Bi2(Te,Se)3 합금분말을 기계적 합금화 공정으로 제조하여 분말 특성을 분석하였으며, 가압소결 후 열전특성의 변화거동을 연구하였다. 순도 99.99% 이상인 Bi, Sb, Te, Se granule을 (Bi1-xSbx)2Te3 및 Bi2(Te1-ySey)3 조성에 맞게 칭량하여 불과 분말의 무게비 5:1로 강구와 함께 공구강 vial에 장입 후, Spex mixer/mill을 이용하여 기계적 합금화 하였다. 기계적 합금화 공정으로 제조한 분말에 대한 X-선 회절분석과 시차 열분석으로 합금화 정도를 분석하였다. (Bi1-xSbx)2Te3 및 Bi2(Te1-ySey)3 합금분말을 10-5 torr의 진공중에서 300℃∼550℃의 온도로 30분간 가압소결하였다. 가압소결체의 파단면에서의 미세구조를 주사전자현미경으로 관찰하였으며, 상온에서 가압소결체의 열전특성을 측정하였다. (Bi1-xSbx)2Te3의 기계적 합금화에 요구되는 공정시간은 Sb2Te3 함량에 따라 증가하여 x=0.5 조성에서는 4 시간 45분, x=0.75 조성에서는 5 시간, x=1 조성에서는 6 시간 45분의 vibro 밀링이 요구되었다. n형 Bi2(Te1-ySey)3 합금분말의 제조에 요구되는 밀링시간 역시 Bi2Se3 함량 증가에 따라 증가하였으며 Bi2(Te0.95Se0.05)3 합금분말의 제조에는 2시간, Bi2(Te0.9Se0.1)3 및 Bi2(Te0.85Se0.15)3 합금분말의 형성에는 3시간의 bivro 밀링이 요구되었다. 기계적 합금화로 제조한 p형 (Bi0.2Sb0.8)2Te3 및 n형 Bi2(Te0.9Se0.1)3 가압 소결체는 각기 2.9x10-3/K 및 2.1x10-3/K 의 우수한 성능지수를 나타내었다.

• Korean Journal of Food Science and Technology
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• v.41 no.4
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• pp.435-440
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• 2009

Acetylcholinesterase (AChE) inhibitors, which enhance cholinergic transmission by reducing the enzymatic degradation of acetylcholine, are the only source of the compound that is currently approved for the treatment of Alzheimer's disease (AD). In these experiments, the concentration samples of green tea extracts were 100, 500, and 1,000 ${\mu}g$/mL. Among them, the highest concentration (1,000 ${\mu}g$/mL) of fresh green tea extracts showed the most potent inhibitory effect on AChE by reducing more than 40% of enzyme activity, and in a concentration-dependent pattern. In addition, we examined the effect of other storing conditions on AChE inhibition. In order to maintain storage for 3 months, the materials were held at the certain storing conditions of temperature (room temperature, 4 and $-20^{\circ}C$) and for water activity (0.81, 0.69, and 0.23). In these storing conditions, the difference in temperature did not contribute to the AChE inhibitory effect. Our presented data showed that the AChE inhibitory effect was affected by the concentration of green tea extract and by water activity (0.81). These results suggest that green tea may serve as a potential dietary source of AChE inhibitor.

• Korean Journal of Food Science and Technology
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• v.30 no.6
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• pp.1480-1483
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• 1998

To know the probable storage conditions for commercially prepared ‘baked egg’ and ‘rolled egg’ products, microbes and quality changes for samples immediately after the production and stored under the several conditions were tested. Sealed samples were stored at 5, 10, 15, $20^{\circ}C$, respectively and tested at 1 or 2-days intervals, opened samples were stored at 15, 20, 30, $37^{\circ}C$, respectively and tested at 6-hr intervals. Coliform bacteria, E. coli, Salmonella, Staphylococci were not detected, and viable cell counts level was under $10^2\;CFU/g$ for samples immediately after the production. The higher the storage temperature and baked eggs rether than rolled eggs showed more rapid microbial growth for both samples. For sealed condition, 14-days at $5^{\circ}C$ for both samples, 7-days for rolled eggs and 5-days for baked eggs at $10^{\circ}C$ were kept their initial microbial level and favorable flavor. For opened condition, it showed remarkable microbial increase after $18{\sim}24\;hr$ for $15{\sim}20^{\circ}C$ and 12 hr for $30{\sim}37^{\circ}C$. From these results, used egg products samples are able to be stored more than 1-week at below $5^{\circ}C$ and opened samples need to be stored at cold storage. At room temperature, it egg products.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.3
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• pp.452-459
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• 2016

Nutritional compositions, volatile compounds, and sensory attributes of grilled and fast-chilled mackerel (Scomber japonicus) were analyzed in order to examine its practical utilization as a food resource compared to commercial frozen mackerel. In the proximate analysis, lipid contents were $27.3{\pm}2.7%$ in grilled and fast-chilled mackerel. Palmitic acid was the most predominant fatty acid (20.68% and 18.88%), and the percentages of polyunsaturated fatty acid were higher than 40% in both. No benzopyrene was found in the grilled mackerel, and even grilling was employed at $260^{\circ}C$. For chemical stabilities, para-anisidine value (8.56 vs. 9.26) and acid value (2.96 vs. 3.35) in grilled mackerel were improved compared to those of commercial mackerel. Moreover, color index of grilled mackerel, a physiological property, showed greater lightness than commercial mackerel. Lastly, analysis of volatile compounds by gas chromatographic analysis and sensory tests by trained panels demonstrated higher potential for grilled mackerel as a highly marketable product compared to commercial mackerel. Taken altogether, the above results provide important preliminary results for utilization of grilled and fast-chilled mackerel as a quality food.

• Food Science and Preservation
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• v.15 no.5
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• pp.648-655
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• 2008

A gamma irradiation process was applied to prolong the shelf-life of grapes and changes in microbiological, physicochemical, nutritional, and sensory characteristics were investigated during 6 weeks of post-irradiation storage at $4^{\circ}C$ and $25^{\circ}C$. Physiochemical characteristics of grapes such as total sugar content, pH, titratable acidity, and anthocyanine content, were stable after 1 kGy of irradiation, a dose recommended by CODEX for fruits and vegetables. The viable cell counts of contaminating microorganisms were reduced 1-2 logs by this radiation dose. After 6 weeks of storage at $4^{\circ}C$ the microbiological quality of irradiated grapes was stable, but all non-irradiated grapes had deteriorated. Whether or not grapes were irradiated, weight loss rapidly increased after 2 weeks of storage at $25^{\circ}C$, whereas weight loss was delayed by storage at $4^{\circ}C$. Immediately after gamma irradiation, the sensory evaluation results did not differ between samples, and the sensory quality of the irradiated grapes remained acceptable for over 6 weeks of storage at $4^{\circ}C$. The results suggest that 1 kGy of gamma irradiation does not detrimentally affect the nutritional or physical characteristics of grapes, especially when cold storage follows radiation treatment. In conclusion, a combination of gamma irradiation and cold storage prolonged the shelf-life of grapes by 6 weeks.

• Journal of Sericultural and Entomological Science
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• v.50 no.2
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• pp.116-121
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• 2012

Cordyceps and its allies fungi has been described as a secret medicine that gives eternal youth and a long life. Some species of Cordyceps are sources of biochemicals, such ascordycepin, with interesting biological and pharmacological properties. Hence, it has been studied to uncover its pharmacological effect. We attempted to study the formation of fruiting bodies and to develop means of mass production Korean isolate of Paecilomyces tenuipes has been inoculated into silkworms, where it reproduced using culture container, mini-kit successfully. Culture container, mini-kit is composed of a cylinder-shaped body and lid. The container is made of translucent polyethylene terephthalate. The size of the container is $82{\times}75mm$, reduced by 10 times as compared with the conventional culture kit. The mini kit has many advantages - high culture amount, ability of maintaining optimal humidity, parasite-free cultivation and high-end appearance. With the kit, the optimal cultivation condition is under $22^{\circ}C$, culture period of 53 days. And synnemata of P. tenuipes could be kept fresh for 14 days at the temperature of under $10^{\circ}C$. Therefore, the Min-kit can be used in both ways as a culture container and a packing kit for end-user customers.

• Journal of Food Hygiene and Safety
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• v.36 no.5
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• pp.382-391
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• 2021

The purpose of this study was to investigate the microbial contamination of red pepper powder distributed within Gyeonggi province in 2020 according to the place of purchase, the country of origin, and whether the HACCP certification and sterilization were conducted, and to evaluate the change of quality according to the storage method. Upon collecting and analyzing 100 samples, Bacillus cereus was detected in 3 cases (2 cases in large supermarkets and 1 case in traditional markets) and Clostridium perfringens in 27 cases (9 cases in large supermarkets and 18 cases in traditional markets). The levels of the total aerobic bacteria were not significantly different between the red pepper powder purchased from large supermarkets and traditional markets. However, the frequency of red pepper powder exceeding 7 log CFU/g of total aerobic bacteria was higher in traditional markets than in large supermarkets. Microbial quality was not significantly different regardless of the storage temperature (30℃, 4℃, -20℃) and the packaging method (zipper bag and clean bag) after 7 months of purchase. However, the moisture contents and ASTA color value of red pepper powder stored at 30℃ decreased remarkably after 3 months of storage. It is desirable to store red pepper powder in a refrigerator or freezer in order to maintain its quality during long-term storage.