• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
• /
• 2003.10a
• /
• pp.188.2-189
• /
• 2003

시설재배 만감류인 부지화 감귤의 수확후 저장유통시 부패 감소 및 상품성 제고를 위하여 환경친화적 전처리방법으로서 중온처리의 적용 가능성을 확인하고자, 제주 서귀포산 부지화(한라봉)감귤의 열수 및 열풍 처리에 따른 저장중 품질특성 변화를 살펴보았다. 표면상처가 없는 일정 크기의 건전 과실을 선별한 후, 각각 52$^{\circ}C$에서 2분(52-2m), 6$0^{\circ}C$에서 20초(60-20s) 동안 열수에 침지하거나 45$^{\circ}C$에서 4시간(45-4h), 8시간(45-8h) 동안 열풍을 가한 다음 5$^{\circ}C$에서 냉각 건조하였다. 충분히 냉각된 과실을 통기성 천공 LDPE 필름에 포장하여 5"C에서 21일, 18$^{\circ}C$에서 7일간 저장하면서 생리, 이화학, 관능적 특성을 측정하였다. 중온처리 직후 초기 호흡률은 처리구 모두 무처리구와 비교하여 다소 높았으나, 저장중 처리구 감귤의 호흡률은 감소하여 21일째는 무처리구와 동일한 수준을 나타내었다. 과실내 기체조성은 저장기간 및 처리구간에 차이를 보이지 않았으나 21일부터는 저장온도 전환에 따라 $CO_2$가 다소 증가하는 양상을 보였다. 과실의 pH, 산도, 경도는 중온처리에 따른 유의적 차이를 구분할 수 없었으나, 고형분 함량과 생체 중량감소율은 열풍처리구에서 다소 높게 유지되었다. 과피 표면색 역시 열풍처리구 (45-8h)가 다른 것에 비해 저장중 짙게 나타났으나 열수처리구에서는 가시적 변화를 발견할 수 없었다. 한편 부패과 발생률에 있어서 열수처리구가 축부병 등에 의한 짓무름 현상 및 곰팡이 발생정도를 가장 낮게 나타내었고, 관능검사에서도 열수처리구가 변색, 시듦, 광택 등의 외관 품질항목에서 유의적으로 우수하게 평가되었다. 결과적으로 중온 열수처리는 부지화 김귤의 수확후 저장유통중 부패과 발생률을 감소시키고 외관품질을 유지하는데 효과적인 전처리방법임을 확인할 수 있었다. 있었다.

• Food Science and Preservation
• /
• v.21 no.4
• /
• pp.544-548
• /
• 2014

This study was conducted to investigate the effects of various heat treatments on the microbial reduction and germination of red radish seeds for the development of effective and economical sterilization methods of improving microbial safety without reducting the germination rate. Hydrothermal treatment was conducted at 60, 65, 70, 75, 80, and $90^{\circ}C$ for 30 and 60 seconds, and dry heat treatment was performed at 70, 80, 90, and $100^{\circ}C$ for 5 minutes. In the seeds that underwent the hydrothermal treatment, time had little effect on the microbial reduction. There was no significant microbial reduction over time. However, there was significant microbial reduction as temperatures increased (p<0.001). The total plate count (TPC) was reduced by more than 3 logs, and Listeria monocytogenes was not detected at temperatures above $70^{\circ}C$. In the seeds that were subjected to the dry heat treatment, the TPC and the population of the L. monocytogenes were significantly reduced as the temperatures increased (p<0.001). After treatment at $100^{\circ}C$ for 5 minutes, the TPC and the L. monocytogenes were reduced by 3 logs. As with the microbial reduction, time had little effect on the germination. There were no significant changes in the germination after the hydrothermal treatment over time; but at the temperatures above $75^{\circ}C$, the germination rate significantly decreased as the temperature increased (p<0.001). When the seeds were soaked after the hydrothermal treatment, their germination was stimulated. The dry heat treatment at temperatures of $80^{\circ}C$ and higher significantly decreased the germination rate as the temperature increased (p<0.001). Dry heat treatment before the germination of the seeds soaked in distilled water for three hours significantly decreased the germination at temperatures greater than $90^{\circ}C$ (p<0.05). This study showed that appropriate heat treatments can increase the microbiological safety and germination of red radish seeds.

• Korean Chemical Engineering Research
• /
• v.54 no.3
• /
• pp.310-314
• /
• 2016

The search for natural antioxidants as alternatives to synthetic products is growing. Microalgae have emerged as a source of natural antioxidants with significant and diverse health-promoting properties. In this study, the effects of hot-water extraction conditions on total polyphenol compounds (TPC) production were investigated for lipid extracted microalgae (LEA). In order to enhance the polyphenol productivity, the extraction variables including solvents, temperature, time and ethanol concentration were optimized. The results showed hot-water extraction provided a higher extraction efficiency than the organic solvents and extraction at high temperatures showed a better extraction efficiency. While hot-water extract showed a higher extraction efficiency compared to 98% ethanol extraction, the mixture of water and ethanol (40:60 v/v) showed the highest production of polyphenols. The maximum polyphenols of 3.35 mg GAE (gallic acid equivalent)/g DM were obtained at the optimized extraction time of 10 min, $100^{\circ}C$ and 40% ethanol, respectively. Although Tetraselmis KCTC 12236BP was preprocessed by hexane to remove lipid for bio-diesel production, the results showed LEA contains relatively high level of polyphenols compared to untreated microalgae which can be used in the production of value-added materials. The predictions obtained from the developed Peleg's model were compared with the experimental data under the same operating conditions. The predicted and experimental data were consistent, indicating the reliability of the model.

• Economic and Environmental Geology
• /
• v.26 no.3
• /
• pp.259-265
• /
• 1993

The variation of H/F coefficient (Hubnerite/Feberite coefficient) and the temperature of formation with depth have been studied for the hydrothermal tungsten-quartz veins from Ssangjeon, Weolag, Cheongyang, and Sannae mines. All samples were selected at the same paragenetic stage and mineral assemblege according to depth. The studied mines provide an opportunity to examine and regional variations in wolframite composition in different provinces. The formation temperature is linearly related to the depth. At the Weolag, Cheongyang and Sannae mines, the H/F ratio of wolframite and filling temperatures of fluid inclusions in quartz show a general tendency to decrease at shallow levels, in spite of different geological settings. This implies the pH of fluid will decrease vertically with falling temperature and the high H/F ratio of wolframite in deep zone result in an increase of pH with depth. The Ssangjeon mine exhibits a tendency to increase slightly upwards at shallow level. This implies a different geochemical environment (high pH environment) for the Ssangjeon mine, as compared to the other three mines. The H/F coefficient pattern suggests that it is a useful geothermometer for vein-type tungsten deposits in Korea. The H/F coefficient as an indication of depth should be examined for use in exploration.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.32 no.6
• /
• pp.779-783
• /
• 1999

The process of alginate preparation was shortened with microwave pretreatment and hot water extraction without any other treatment. The yield of extracted alginate was very different according to raw material and microwave treatment conditions. The yield of extracted alginate from sea mustard was higher than sea tangle and increased with the temperature rise and time of microwave treatment. Optimum extraction conditions by microwave treatment were 90 min at $100^{\circ}C$ for the sea mustard and 120 min at $100^{\circ}C$ for the sea tangle. On the other hand, the solubility of the alginate from sea mustard was $69\%\~80\%$ and the viscosity were 8.7$\~$1.5 cps, respectively. The solubility and the viscosity of the sea tangle alginate was higher than the sea mustard to $77\~84\%$ and in the range of 8.9$\~$1.8 cps, respectively. The extraction temperature by hot water greatly influenced on the yield of alginate, but the solubility and viscosity was not affected by the hot water extraction. The molecular weight of alginate obtained through the extraction by $Na_2CO_3$ solution and the microwave pretreatment was 800 kDa, and in the range of 12$\~$45 kDa, respectively.

• Food Science and Preservation
• /
• v.19 no.6
• /
• pp.901-908
• /
• 2012

This study was conducted to analyze the antioxidant activities of fermented black jujube and to compare these with those of dried jujube, for the development of functional materials. The antioxidative activities of dried jujube and fermented black jujube extracts were analyzed by electron-donating ability (EDA) using 1,1-diphenyl-2-picryl hydrazyl (DPPH), superoxide-dismutase-(SOD)-like activity by pyrogallol, nitrite-scavenging ability, and xanthin oxidase. The yield of the fermented black jujube extracts was higher than that of the dried jujube extracts, and that of the ethanol extracts was higher than that of the hot-water extracts. The total phenol contents of the hot-water extracts from fermented black jujube were higher. The EDA values of the hot-water and ethanol extracts from fermented black jujube and dried jujube increased with an increase in extract concentration, and were about 85% in a $1000{\mu}g/mL$ extract concentration. The SOD-like activity increased with an increase in extract concentration. The SOD-like activity of the hot-water extract from fermented black jujube was higher than that of the other extracts. The nitrite-scavenging ability at pH 1.2 of the hot-water extracts from dried jujube was higher than that of the other extracts. The xanthine oxidase inhibitory activities of the hot-water and ethanol extracts from fermented black jujube were higher than those of the other extracts, and increased along with the concentrations of the extracts.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.5 no.2
• /
• pp.145-154
• /
• 2007

In hydrothermal reaction tests, smectite-to-illite conversion was identified using a domestic bentonite which is favorably considered as a buffer material, and its dependency on various hydrothermal conditions was investigated. The analysis results of the XRD and Si concentration indicated that the smectite-to-illite conversion was a major process of bentonite alteration under the hydrothermal conditions. The temperature, potassium concentration in solution, and pH were observed to significantly affect the smectite-to illite conversion. A model of conversion reaction rate was suggested to evaluate the long-term stability of smectite composing a major constituent of bentonitic buffer. It was expected from the evaluation results that the smectite would keep its integrity for very long disposal time under a normal condition, whitens it might be converted to illite by 50 percent after over $5{\times}10^4$ year of disposal time under a conservative condition and consequently lose its swelling capacity as a buffer material of a repository.

• Korean Journal of Food Science and Technology
• /
• v.38 no.3
• /
• pp.361-368
• /
• 2006

Extruded ginseng was manufactured using twin-screw extruder under 300 rpm screw speed, 21 kg/hr feed rate, $80-150^{\circ}C$ extrusion temperature, and by addition of water (12.1-30.6%). Extraction yield and contents of total carbohydrate and uronic acid in extruded ginseng at room temperature extraction (RT) increased with increasing extrusion temperature, whereas those of boiling temperature extracts (BT) were not affected by increasing extrusion temperature. Contents of nonstarch polysaccharide (NSP) in RT and BT extracts increased 340 and 142%, respectively, compared to that of raw ginseng. Main sugar compositions of NSP in RT and BT extracts were arabinose, galactose, and glucose. Extraction yields of total and crude saponins in extruded ginseng at optimize extrusion condition were higher than that of raw ginseng. In RT extracts, molecular weights of polysaccharides from raw were higher than that of extruded ginseng polymer, whereas in BT extracts molecular weights of polysaccharides from extruded ginseng were higher than those of raw ginseng polysaccharides.

• Food Science and Preservation
• /
• v.14 no.5
• /
• pp.487-491
• /
• 2007

This study was conducted to investigate the effect of treatment with squeous chlorine dioxide and hot water on the germination of radish (Raphanus sativus L.) seeds, and reduction of microbial load on the seeds. Increases in treatment and the concentration of aqueous chlorine dioxide in water resulted in increasing reductions in the counts of total aerobic microbes. Seeds treated with aqueous chlorine dioxide (100 ppm/20min, 200ppm/20min) showed about a 10-fold decrease in microbial loads. Germination of seeds was not adversely affected by any treatment tested, although the germination rate of seeds in the group treated at $55^{\circ}C$ for 20 min was reduced by 10% compared to that of control. Combined treatment with hot water and aqueous chlorine dioxide yielded better out comes in both microbial reduction and seed germination rate than did single treatments. A combined treatment with 100 ppm aqueous chlorine dioxide and hot water($45^{\circ}C$ or $50^{\circ}C$) resulted in about a 100-fold decrease in microbial load whereas germination rate showed only a slight increase to $97.0{\sim}97.7%$. Total aerobic microbial counts in radish seeds were decreased by aqueous chlorine dioxide and hot water treatment in the order. aqueous $CIO_2$+ hot water > aqueous $CIO_2$ > chlorinated water > hot water > control.

• Korean Chemical Engineering Research
• /
• v.55 no.3
• /
• pp.358-362
• /
• 2017

In this study, the optimization of extraction parameters (solvent, temperature, time, solvent concentration) for the maximization of polyphenol extraction was performed to produce value-added food and cosmetic additives using a byproduct of coffee extraction process (coffee residue). All of the extraction parameters evaluated in this experiment had significant effects on polyphenol extraction and the results showed the effect of NaOH concentration on the polyphenol production was most significant among tested parameters. Especially, hot water extraction using acid or base was effective rather than hot-water extraction and the addition of 0.1 mol of NaOH increased 1.5 times extraction concentration compared with hot-water extraction using distilled water. It was found that hot-water extraction with NaOH was more effective than hot-water extraction, and 36.5 mg GAE/g DM was obtained under optimum condition of $100^{\circ}C$, 2 mol of NaOH and 30 min. This result was 2.9 times higher than that of 12.5 mg GAE/g DM obtained from the hot-water extraction before optimization. Thus, coffee residue could be used for food and cosmetic industry as a high-value additive such as antioxidant.