• The Korean Journal of Food And Nutrition
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• v.30 no.6
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• pp.1149-1156
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• 2017

We investigated the quality characteristics and the antioxidant efficacy of roasted maize tea according to different moisture contents (9% to 14%) using the puffing system (PS) and the roasting system (RS). Compared with the RS, the PS caused higher turbidity (0.017 vs. 0.003 in PS-14% vs. RS-14%), brown color intensity (0.170 vs. 0.059 in PS-14% vs. RS-14%), a-values (0.20 vs. -0.44 in PS-14% vs. RS-14%), b-values (7.90 vs. 5.57 in PS-14% vs. RS-14%), and a lower L-value (19.67 vs. 21.03 in PS-14% vs. RS-14%). Total polyphenol and flavonoid contents of roasted maize tea were increased along with the moisture content and they were higher with the PS (polyphenol; 5.95 mg GAE/g, flavonoids; 1.27 CE/g in PS-14%) than with the RS (polyphenol; 5.39 mg GAE/g, flavonoids; 1.12 mg CE/g in RS-14%). The DPPH and ABTS radical scavenging effects of roasted maize tea were also increased along with the moisture content, and the scavenging efficacy was significantly higher with the PS (DPPH; 160 mg TE/100g, ABTS; 507 mg TE/100g in PS-14%) compared with the RS (DPPH; 120 mg TE/100g, ABTS; 362 mg TE/100g in RS-14%). The polyphenol levels were significantly correlated with turbidity, brown color intensity, and L, a, and b-values of the roasted maize tea. In addition, an increase of the total polyphenol content in roasted maize tea induced antioxidant activities. As a result, an increase in polyphenols during the roasting process induced antioxidant activities which could prevent damage from free radicals.

• Journal of the Mineralogical Society of Korea
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• v.26 no.1
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• pp.9-18
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• 2013

In order to optimize the gold leaching process from refractory sulfide concentrate, a chlorine-hypochlorite solution with varying concentrations and temperatures were applied to salt-roasted concentrate. The concentrate consisted of pyrite, chalcopyrite, and galena, which were turned into hematite through air-roasting at $750^{\circ}C$. Also these concentrates were changed into hematite and nantokite (CuCl)) through salt (NaCl)-roasting at $750^{\circ}C$. The results of the gold leaching experiments showed that the best gold leaching parameters were obtained when the hydrochloric acid-sodium hypochlorite mix was at a ratio of 1 : 2, the added concentration was 1.0 M concentration, the pulp density was 1.0%, and the leaching was done at a $60^{\circ}C$ leaching temperature. The leaching rate for gold was much greater in the roasted concentrate than in the raw concentrate. The leaching rate was greater in the salt-roasted concentrate than in the plain roasted concentrate too. From XRD analysis, quartz was found in the salt-roasted concentrate and in the solid residue from the chlorine-hypochlorite leaching solution at $60^{\circ}C$.

• Economic and Environmental Geology
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• v.47 no.6
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• pp.645-655
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• 2014

In order to obtain pure metallic Te from gold concentrate, roasting treatment, hypochlorite leaching, Fe removal and electrolysis experiments were carried out. The contents of Au, Ag and Te from the concentrate sample and roasted sample were much more soluble in the hypochlorite solution than in aqua regia digestion, whereas the metals Pb, Zn, Fe and Cu were easier to leach with the aqua regia than the hypochlorite. With the addition of NaOH in the hypochlorite leaching solution prior to electrolysis, the Fe removal rate achieved was only 96% in the concentrate sample, while it reached 98% in the roasted sample. The results of electrolysis for 240 min, 98% of the metallic copper was recovered from the concentrate sample, while 99% was obtained from the roasted sample due to the removal of S by roasting. The amount of anode slime was also greater in the electrolytic solution with the roasted sample than with the concentrate sample. The results on the anode slime after the magnetic separation process showed the amount of metallic pure native tellurium recovered was greater in the roasted sample than in the concentrate sample.

• Clean Technology
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• v.28 no.2
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• pp.103-109
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• 2022

Nd-Fe-B waste permanent magnet contains about 20~30% rare earth elements and about 60~70% iron elements, and the rare earth and iron components were recovered through sulfuric acid leaching and fractional crystallization. Oxidation roasting was not performed for separation and recover of the rare earth and iron elements. The leaching characteristics were confirmed by using as variables the sulfuric acid concentration and the mineral solution concentration ratio. Sulfuric acid leaching was carried out for 3 hours for each sulfuric acid concentration. The leached solid phase was characterized for its crystalline phase, composition, and quantitative components by XRD and XRF analysis, and the filtrate was analyzed for components by ICP analysis. With sulfuric acid leaching at 3M sulfuric acid concentration, neodymium compounds were formed, the iron content was the least, and the recovery rate was high. After the filtrate remaining after sulfuric acid leaching was subjected to fractional crystallization through evaporation and concentration, the neodymium component was found to be concentrated 7.0 times and the iron component 2.8 times. In this study, the recovery rate of waste permanent magnets through sulfuric acid leaching and a fractional crystallization method without an oxidation and roasting process was confirmed to be about 99.4%.

• Korean Journal of Food Science and Technology
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• v.31 no.4
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• pp.894-898
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• 1999

Aroma components of Ookjook tea made from Polygonatum involucratum Maxim roots were collected and identified. The extraction of aroma compounds was accomplished by a simultaneous distillation and extraction method using a Likens and Nickerson's extraction apparatus. The concentrated extract was analyzed and identified by GC and GC-MS. The most abundant aroma components of this tea were furanic compounds including 2-furfural, 2-methyl-dihydro-3(2H)-furanone, 2-acetylfuran and 5-methylfurfural. These compounds seem to be originated from the thermal degradation of carbohydrates during the roasting process. Alkylpyrazines and acids including propionic acid increased slightly during the period of manufacturing process of Ookjook tea. Furanic compounds originated from the thermal degradation of carbohydrates and alkypyrazines from aminocarbonyl reaction seemed to be the important contributors to the aroma of the Ookjook tea.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.409-412
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• 2001

The high purity manganese oxides were made from the dust, generated in AOD process that produces a medium-low carbon ferromanganese and collected in the bag filter. Manganese oxide content in the dust was about 90%, and its phase was confirmed as Mn₃O₄. In the extraction of manganese, because of remaining amorphous MnO₂, the dust was reduced to MnO by roasting with charcoal. The pulp density of the reduced dust can control pH of the solution more than 4 and then Fe ion is precipitated to a ferric hydroxide. Because a ferric hydroxide co precipitates with Si ion etc, Fe, Si ion was removed f개m the solution. Heating made water to be volatized and nitrates was left in reactor Then nitrates were a liquid state and stirring was possible. Among the nitrates in reactor, only the manganese nitrate which have the lowest pyrolysis temperature pyrolyzed into β-MnO₂powder and NO₂(g) at the temperature less than 200℃. When the pyrolysis of manganese nitrate has been completed about 90%, injection of water stopped the pyrolysis. Nitrates of impurity dissolved and the spherical high purity β-MnO₂powders were obtained by filtering and washing. Mn₂O₃or Mn₃O₄ powder could be manufactured from β-MnO₂powder by controlling the heating temperature. Lastly, a manufactured manganese oxide particle has 99.97% purity.

• Korean Journal of Food Science and Technology
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• v.44 no.3
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• pp.269-273
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• 2012

The principal objective of this study was to estimate the benzo(a)pyrene contents in commercial vegetable oils available in the Korean market and to assess the effects of various processing steps for vegetable oils on the contents of benzo(a)pyrene. Benzo(a)pyrene content in the studied commercial vegetable oils, crude oils, and raw materials were found to be lower than the maximum levels of 2 ppb. In both refined and pressed oil, the benzo(a)pyrene contents can be reduced through refining steps. However, an evident increase of benzo(a)pyrene contents during both the expeller process for corn oil and the roasting process for sesame oil was observed. This result indicates that the processing procedure, particularly heat treatment and refining steps would be critical in managing the benzo(a)pyrene contents in vegetable oils.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.1
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• pp.68-75
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• 2016

This study was conducted to provide information regarding changes in antioxidant activity in response to conching temperatures, conching times, and cacao mass content (CMC) in dark chocolate. The radical scavenging activities and functional components of cacao nibs were highest for raw cacao nib (R0) under all conditions. Moreover, antioxidant activities and functional compounds increased during roasting for 25 min. As the conching temperature increased, the radical scavenging activities and functional components increased. Quantitative analysis of major catechin-derived compounds by HPLC revealed that R0 had the highest value for other roasted cacao nibs in all aspects (P<0.05). The content of procyanidin B2, catechin, and epicatechin increased during roasting for 25 min. Finally, evaluation of couvertures revealed that procyanidin B1 content increased as conching time increased to 48 h, except for 70% CMC and conched at $60^{\circ}C$ (HH) and 70% CMC and conched at $50^{\circ}C$. Overall, HH48 contained the richest catechin-derived components.

• Journal of Nutrition and Health
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• v.52 no.5
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• pp.413-421
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• 2019

Purpose: Astragalus membranaceus (AM) is an important traditional medicinal herb. Pharmacological research has indicated that AM has various physiological activities such as antioxidant, anti-inflammatory, immunoregulatory, anticancer, hypolipidemic, antihyperglycemic, and hepatoprotective activities. The bioactive substances responsible for the physiological activities in AM, including many antioxidant substances, change during the roasting process. This study investigated and compared the changes in the antioxidant constituents of AM caused by roasting. Methods: DPPH (1,1-diphenyl-2-picryl hydrazyl) and $ABTS^+$ (2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt) radical scavenging activities and their total phenolic content (TPC) were measured. High-performance liquid chromatography (HPLC) analysis was performed to confirm any changes in the isoflavonoids of roasted AM (R-AM),. The cell viability of UVB-induced HDF (Human dermal fibroblast) cells treated with AM and R-AM extracts was investigated. The comet assay was used to examine the inhibitory effects of R-AM extracts on DNA damage caused by oxidative stress. Results: The DPPH and $ABTS^+$ radical scavenging activities were $564.6{\pm}20.9$ and $108.2{\pm}3.1$ ($IC_{50}$ value) respectively, from the 2R-AM. The total phenol content was $47.80{\pm}1.40mg$ GAE/g from the 1R-AM. The values of calycosin and formononetin, which are the known isoflavonoid constituents of AM, were $778.58{\pm}2.72$ and $726.80{\pm}3.45{\mu}g/g$ respectively, from the 2R-AM. Treatment of the HDF cells with R-AM ($50{\sim}200{\mu}g/mL$) did not affect the cell viability. Furthermore, the R-AM extracts effectively protected against UVB-induced DNA damage. Conclusion: The findings of this study indicate that R-AM increases its isoflavonoid constituents and protects against UVB-induced DNA damage in HDF cells.

• Food Science and Preservation
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• v.22 no.2
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• pp.218-224
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• 2015

Crickets have been used as crude drug for treating fever and hypertension in East Asia. This study was carried out to investigate the quality characteristics such as the microbial and nutrient contents of crickets (Gryllus bimaculatus) prepared with various processing conditions for use as food. These conditions included the lyophilization process (LP), hot-air process (HP, $90^{\circ}C$ for 7 hr), roasting process (RP, $160^{\circ}C$ for 40 min), and frying process (FP, $180^{\circ}C$ for 30 sec). The total bacterial population of the crickets was 5~7 log CFU/g, but Coliform and E. coli were not detected. The major fatty acids in all the samples were palmitic acid (C16:0), oleic acid (C18:1), and linoleic acid (C18:2). The level of polyunsaturated fatty acids was highest (63.55 g/100 g) in the LP-processed crickets. As for the amino acid content, the glutamic acid level was highest in all the samples, and the RP and FP decreased by 12.01% and 53.88%, respectively, compared to that of the LP. The mineral contents were highest in the LP-processed crickets. Hg was detected at about 1.0 ppb in all the samples, but its level was lower than the residue tolerance level in the Korean Food Code. Such conditions should be considered to better understand the quality characteristics of crickets in food processing.