• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.24 no.3
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• pp.97-106
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• 2018

This study aimed at examining the suitability of $Tenax^{(R)}$ for the migration testing of food packaging materials, which is currently approved in the EU as a dry food simulant. The results are used as a basis to examine the feasibility of introducing $Tenax^{(R)}$ to Korean regulation. The OMVs of test specimen into various solvents (diethyl ether, ethanol, pentane, and acetone) after exposure to $100^{\circ}C$ for 1 hr were compared. Diethyl ether showed the highest OMV ($1.33mg/dm^2$) among the solvents tested. When the tests were conducted with different amounts of $Tenax^{(R)}$ of 2, 4, or 8 g per specimen, the OMVs were 0.75, 1.33 and $1.40mg/dm^2$, respectively. The OMV obtained with a closed system after wrapping with aluminum foil showed a significantly higher OMV ($1.61mg/dm^2$) than that without aluminum wrapping ($1.318mg/dm^2w$) and an open system without lid ($1.06mg/dm^2$). The specific migration rates of surrogates spiked in the polyethylene test film and paper samples into $Tenax^{(R)}$ were compared with those into liquid food simulants including 95% ethanol and n-heptane, and actual foods such as starch, skim milk, and sugar. In general, the specific migration levels of surrogates into $Tenax^{(R)}$ were similar compared with n-heptane, however those were significantly higher than into actual foods. These results suggest that $Tenax^{(R)}$ may be used as a food simulant for the long-term preservation of dried foods and paper products. However, more studies need to be conducted to investigate the factors influencing the migration into $Tenax^{(R)}$, such as the types of foods and packaging materials tested, migration conditions, and surrogates properties etc.

• Food Engineering Progress
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• v.21 no.4
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• pp.351-359
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• 2017

This study investigates the quality characteristics of dough and bread added with 6% chestnut shell powder and extruded chestnut shell powder at various conditions. As extrusion process variables, melt temperature ($110^{\circ}C$, $130^{\circ}C$, $150^{\circ}C$) and moisture (25% and 30%) were controlled. Total dietary fiber content was slightly increased in extruded chestnut shell powder group. In the farinogram, absorption was significantly increased in the group of 25% moisture content and 30% moisture content (p<0.05). After 2 hours and 3 hours, the leavening heights of dough for control showed a similar tendency to that of dough with extruded chestnut shell at a melt temperature $150^{\circ}C$ and with moisture content of 25% and 30%. Specific volume was the highest at a control of $3.74{\pm}0.08cc/g$ and extruded chestnut shell powder group was slightly higher than the chestnut shell powder group. Firmness after 1 day on control of $107.42{\pm}14.52g$ was similar to that of the bread with extruded chestnut shell at a temperature of $150^{\circ}C$ and moisture content of 25% for $113.33{\pm}6.17g$. In conclusion, the extrusion-cooking of chestnut shell powder improved the quality characteristics of dough and bread. The optimum combinations of conditions in tested range were melt temperature at $150^{\circ}C$ and moisture content at 25%, and melt temperature at $130^{\circ}C$ and moisture content at 30%.

• The Korean Journal of Mycology
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• v.49 no.3
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• pp.337-349
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• 2021

This study aimed to isolate wild yeasts from water and soil sample of the Nonsan stream and Sapgyoho (lake) in Chungcheonnam-do, Korea, and to further characterize previously unrecorded wild yeast strains. In total, 102 strains, representing 55 different species of wild yeast were isolated from 95 samples collected from the Jangseoncheon and Ipchoncheon of Nonsan stream in Jellabuk-do and Chungcheonnam-do. Among these, 33 strains were isolated from alkalophilic yeast extract-peptone-dextrose (YPD) medium (pH 9.0), and 9 strains were isolated concurrently on general YPD medium (pH 6.5) and alkalophilic medium. Seventeen strains of Cryptococcus laurentii were predominantly isolated. Additionally, 65 strains, representing 27 different species of wild yeast were isolated from 58 samples obtained from Sapgyoho (lake). Among the 82 isolated wild yeast strains, 8 strains, including Candida fructus JSC 72-1(JSL-GGU 015), had not previously been recorded. All 8 previously unrecorded yeasts were oval in shape except C. fructus JSC72-1(JSL-GGU-015), and only the Filobasidium chernovii JSC39-1(JSL-GGU-013) strain formed spores. All strains except Pseudosydowia eucalypti JSC23-6(JSL-GGU-012) grew well in yeast extract-peptone-dextrose (YPD) and yeast extract-malt extract media and grew in vitamin-free medium. Four strains, including P.eucalypti JSC23-6(JSL-GGU-012) grew well in 15% NaCl-containing YPD medium. F.chernovii JSC39-1(JSL-GGU-013) and Sirobasidium intermedium JSC7-3(JSL-GGU-014) assimilated lactose, and five strains, including F. chernovii JSC39-1(JSL-GGU-013) also assimilated starch. All strains were resistant to 800 ppm of Ca, Cu, Li, and Mg ions.

• Journal of Life Science
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• v.29 no.11
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• pp.1173-1178
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• 2019

The purpose of this study was to isolate an agar-degrading marine bacterium and characterize its agarase. Bacterium BK-1, from Gwanganri Beach at Busan, Korea, was isolated on Marine 2216 agar medium and identified as Agarivorans sp. BK-1 by 16S rRNA gene sequencing. The extracellular agarase, characterized after dialysis of culture broth, showed maximum activity at pH 6.0 and $50^{\circ}C$ in 20 mM Tris-HCl buffer. Relative activities at 20, 30, 40, 50, 60, and $70^{\circ}C$ were 67, 93, 97, 100, 58, and 52%, respectively. Relative activities at pH 5, 6, 7, and 8 were 59, 100, 95, and 91%, respectively. More than 90% of the activity remained after a 2 hr exposure to 20, 30, or $40^{\circ}C$; about 60% of the activity remained after a 2 hr exposure to $50^{\circ}C$. Almost all activity was lost after exposure to 60 or $70^{\circ}C$ for 30 min. Zymography revealed three agarases with molecular weights of 110, 90, and 55 kDa. Agarose was degraded to neoagarobiose (46.8%), neoagarotetraose (39.7%), and neoagarohexaose (13.5%), confirming the agarase of Agarivorans sp. BK-1 as a ${\beta}$-agarase. The neoagarooligosaccharides generated by this agarase could be used for moisturizing, bacterial growth inhibition, skin whitening, food treatments, cosmetics, and delaying starch degradation.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.67 no.1
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• pp.9-16
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• 2022

Rice is one of the most important staple foods in Wnju, Jeonbuk, South Korea. However, rice consumption has dramatically decreased as eating habits have diversified owing to rapid economic growth. Recently, floury endosperm rice varieties have been developed to invigorate the rice processing industry, because dry-milled rice flour is economically and environmentally suitable for massive rice flour distribution. The National Institute of Crop Science has developed 'AromaT', an early-maturing black rice with floury-endosperm, suitable for tea and dry milling. 'AromaT' was derived from a cross between 'Suweon542' as the floury endosperm source and 'Heugjinju' as the black and aromatic source. In this study, 'AromaT' and its parents, 'Suweon542' and 'Heugjinju', were analyzed for agronomic traits, anthocyanin content, and their major physicochemical properties by different planting date. The field experiment was conducted in Wanju, Jeollabuk-do Province, South Korea, in 2019. The transplanting dates were May 30 (ordinary season), June 25 (double-cropping season), and July 10 (late season). The yield performance of brown rice 'AromaT' was 330 kg/10 a in the double-cropping cultivation method and was the highest among the transplanting dates. The floury endosperm of 'AromaT' was derived from 'Suweon542' containing 'flo7', located on chromosome 5 and known to control floury endosperm. With the late planting date, the anthocyanin content of 'AromaT' was 570.5 mg/100 g, much higher than that of 'Heugjinju' (376.3 mg/100 mg). The brown rice of 'AromaT' also exhibited the pop-corn-flavoring 2-acetyl-1-pyrroline, exclusively detected in aroma rice varieties. The average particle sizes of 'AromaT' and 'Suweon542' were 67.12 ㎛ and 70.9 ㎛, respectively, lower than that of 'Heugjinju' (95.5 ㎛) with a black transparent endosperm. The average damaged starch content of 'AromaT' was 8.1%, lower than that of 'Heugjinju' (10.05%) and Suweon542 (9.5%). As a result, 'AromaT' with high anthocyanin content, fine particle size, and low damaged starch content is expected to provide a new rice material in various processing fields.

• Korean Journal of Food Science and Technology
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• v.54 no.4
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• pp.455-461
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• 2022

In this study, kombucha was prepared using saccharified rice solution to assess this possible means of increasing rice consumption. Chucheong rice yielded the highest starch content (80.40±1.33%) when used to produce saccharified rice solution. The resultant saccharified rice solution showed the highest 10.42 °Brix at 90 min of saccharification. Chamdream rice yielded the highest acidity at 0.38%, and Kawaji No.1 yielded the lowest at 0.24%. Organic acid analysis on the 15th day of fermenting kombucha made with different rice varieties indicated an acetic acid content of 111.70±1.09 ppm in Chamdream, and 46.86±1.00 ppm in Dongjinchal. Comparison of enzymes used in saccharified rice kombucha fermentation revealed that α-amylase resulted in the highest acidity (1.06%), and β-amylase yielded the lowest acidity (0.58%). Kombucha with green tea yielded the highest acidity (1.09%), and kombucha with rooibos tea yielded the lowest (0.37%). Polyphenol analysis indicated that the amount of polyphenol increased the most (1,623.75 ppm to 3,989.00 ppm) on day 0 of fermentation with green tea. Organic acid analysis revealed that the acetic acid content of kombucha supplemented with green tea increased from 172.89 ppm on day 0 of fermentation to 2,649.11 ppm on day 15. Kombucha with 2.0% added alcohol had the highest acidity (1.32%), and kombucha with 0.5% alcohol had the lowest (0.97%). Taken together, these results confirm that it is possible to make kombucha using saccharified rice solutions.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.1
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• pp.98-102
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• 1995

Popped popcorn generally have a regular popping direction and typical shape. But the reason and mechanism are not clear yet. This experiment was carried out to investigate the shape moulding factor of popped popcorn. Pericarp thickness of tip-cap section of kernels is slightly thicker than that of top section and this fact provides the important information to the reason. Popping starts when the moisture pressure of heated popcorn is increased and reaches at the critical pressure. Therefore, in the same moisture pressure conditions, top sections are bursted first because their pericarp section is thinner than that of tip-cap section. At the very moment tip-cap sections pull down the top sections of peri carp as bi-metal does. So kernels which removed tip-cap section showed the irregular popping shape because they lost the tip-cap pericarp function. How-ever, kernels which removed embryo showed the typical popping shape but their popping volume was small due to emition and shortage of critical moisture pressure. But kernels which removed the whole pericarp and top pericarp were not popped at all because moisture was entirely emitting out of kernels. These results suggest that the shape moulding factor of popped popcorn is the pericarp thickness differences between the top and tip-cap section of kernels.

• Journal of The Korean Society of Grassland and Forage Science
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• v.42 no.4
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• pp.249-257
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• 2022

This study was conducted to comparison analysis growth characteristics, yield and forage quality of 18silage corn varieties grown in paddy and upland fields. In this condition, days to silking of Sinhwangok was the shortest with 78 days and Kangdaok the longest with 92 days. Moreover it was confirmed that the difference of days to silking at this condition greatly occurred in the late species than in the precocious species. The height and ear height ratio of corn grown in paddy decreased by 5~10% and increase by 10~15% compared to upland, respectively. It was confirmed that the ear ratio of corn which enhances the forage quality was highest in Sinhwangok at paddy and upland and most of the varieties decreased by 10~30% at paddy rather than upland. The length of ear was also reduced by 10~25%. In fresh yield, Dacheongok showed the highest yield at 65,750 kg/ha in upland and 38,830 kg/ha in paddy. Similar to the fresh yield, dry and TDN yield in Dacheongok also showed the highest yield at 36,910 kg/ha, 18,040 kg/ha in upland and 21,670 kg/ha, 14,390 kg/ha in paddy, respectively. As a result of analyzing crude protein and starch from seeds to evaluate the feed value of corn for silage, there was no difference between cultivars grown in this condition. In addition, as a result of analyzing the contents of ADF and NDF using leaves, stems and seeds, the contents of leaves and stems were lower in P3394 and P1543 at the upland and lower in Singwangok and Daanok when cultivated at paddy. Moreover ADF and NDF contents were decreased in some varieties in paddy rather than upland. Therefore, there is no significant difference in the feed value of corn varieties grown in this condition, it is possible to cultivate corn in paddy if normal growth is achieved through drainage management.

• Journal of Life Science
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• v.33 no.4
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• pp.357-362
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• 2023

This report looks at an agar-degrading marine bacterium and characterization of its agarase. Agar-degrading marine bacterium JS-1 was isolated with Marine agar 2216 media from seawater from the seashore of Sojuk-do, Changwon in Gyeongnam Province, Korea. The agar-degrading bacterium was named as Agarivorans sp. JS-1 by phylogenetic analysis based on 16S rRNA gene sequencing. The extracellular agarase was prepared from the culture media of Agarivorans sp. JS-1 and used for characterization. Relative activities at 20℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, and 60℃ were 70%, 74%, 78%, 83%, 87%, 100%, 74%, and 66%, respectively. Relative activities at pH 5, 6, 7, and 8 were 91%, 100%, 90%, and 89%, respectively. Its extracellular agarase showed maximum activity (207 units/l) at pH 6.0 and 50℃ in 20 mM Tris-HCl buffer. The residual activity after heat treatment at 20℃, 30℃, and 50℃ for 30 minutes was 90%, 70%, and 50% or more, respectively. After a 2-hour heat treatment at 20℃, 30℃, 35℃, 40℃, and 45℃, the residual activity was 80%, 68%, 65%, 63%, and 57%, respectively. At 50℃ and above, after heat treatment for 30 minutes, the residual activity was below 60%. Thin layer chromatography analysis suggested that Agarivorans sp. JS-1 produces extracellular β-agarases as they hydrolyze agarose to produce neoagarooligosaccharides such as neoagarohexaose (20.6%), neoagarotetraose (58.5%), and neoagarobiose (20.9%). Agarivorans sp. JS-1 and its thermotolerant β-agarase would be useful in the production of neoagarooligosaccharides, showing functional activity such as inhibition of bacterial growth and delay of starch degradation.

• Resources Recycling
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• v.32 no.1
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• pp.50-59
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• 2023

The amount of dust generated during the dissolution of scrap in an electric arc furnace is approximately 1.5% of the scrap metal input, and it is primarily collected in a bag filter. Electric arc furnace dust primarily consists of zinc and ion. The processing of zinc starts with its conversion into pellet form by the addition of a carbon-based reducing agent(coke, anthracite) and limestone (C/S control). These pellets then undergo reduction, volatilization, and re-oxidation in rotary kiln or RHF reactor to recover crude zinc oxide (60%w/w). Next, iron is discharged from the electric arc furnace dust as a solid called Fe clinker (secondary by-product of the Fe-base). Several methods are then used to treat the Fe clinker, which vary depending on the country, including landfilling and recycling (e.g., subbase course material, aggregate for concrete, Fe-source for cement manufacturing). However, landfilling has several drawbacks, including environmental pollution due to leaching, high landfill costs, and wastage of iron resources. To improve Fe recovery in the clinker, we pulverized it into optimal -sized particles and employed specific gravity and magnetic force selection methods to isolate this metal. A carbon-based reducing agent and a binding material were added to the separated coarse powder (>10㎛) to prepare briquette clinker. A small amount (1-3%w/w) of the briquette clinker was charged with the scrap in an electric arc furnace to evaluate its feasibility as an additives (carbonaceous material, heat-generating material, and Fe source).