• Korean Journal of Food Science and Technology
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• v.42 no.4
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• pp.452-458
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• 2010

This study aimed at improving the packaging technology of Yukwa to improve the quality and extend the shelflife using secondary packaging. After packaging the Yukwa using an OPP film, P2, P3, and P4 packaging materials were applied secondarily. Various films including (1) P1: OPP (oriented polypropylene), (2) P2: P1+OPP/LLDPE (linear low density polyethylene), (3) P3: P1+PET (polyethylene terephthalate)/NY (nylon)/CPP (cast polypropylene) and (4) P4: P1+PET/AL (aluminum)/NY/CPP (P4) were used for packaging Yukwa. The experiment was conducted at $25^{\circ}C$ for 12 weeks. P1 showed the highest acid value score (1.26 mg KOH/g), and P3 had the highest peroxide value score (32.91 meq/kg) among all packaging groups. Nevertheless, these values did not exceed the guideline values of 2.0 g KOH/g and 40 meq/kg specified in the Korean food code. The overall color difference showed a tendency for decreasing Hunter 'L' values and increasing 'a' and 'b' values; however, no noticeable difference in the outer appearance was observed in any of the packaging treatments except in the P1 for greater than 10 weeks of storage. Some texture defects were observed in the Yukwa when the moisture contents dropped below 5%. The P4 packaging treatment had the lowest moisture permeability and showed the least rheological deterioration change, followed by P3 and P2. In conclusion, the use of a secondary packaging with less gas and moisture permeability was more effective for maintaining the quality and extending the shelf-life of Yukwa than other types of packaging material.

• Korean Journal of Food Science and Technology
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• v.40 no.4
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• pp.460-465
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• 2008

This study examined the effect of head formation on the quality maintenance of minimally processed lettuce (Lactuca sativa L.) samples. The fresh-cut lettuce samples were packed in $20{\times}15{\times}5$ cm polypropylene+polyethylene terephthalate tray, and were then stored at $4^{circ}C$ for up to 8 days. According to the results, the sample with 100% head formation had lower sugar, minerals (Ca, Na, Fe, Mg, K), and chlorophyll contents compared to the sample with 70% head formation. The 70% head formed lettuce had higher vitamin C content at 3.30 mg/100 g, whereas the 85% and 100% formed samples had lower levels of 2.61 and 2.10 mg/100 g, respectively. The polyphenol oxidase (PPO) activity of the 70% formed lettuce was 240 unit/g, while the 100% formed sample had almost 2-fold higher activity. However, the 100% formed lettuce had greater firmness than all other samples. Overall, among the fresh-cut lettuces, the sample with 70% head formation showed more positive effects in terms of quality maintenance.

• Food Science and Preservation
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• v.19 no.6
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• pp.807-812
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• 2012

This study was investigated the changes in quality of heat treated fresh-cut lotus roots using various packaging materials. Lotus roots were purchased from Daegu, Korea. Lotus roots were washed, peeled and sliced with a sharp ceramic knife. The prepared peeled and sliced lotus roots were dipped for 45 sec in water at $55^{\circ}C$. After air-dried at room temperature, the slices were packaged with polyethylene films, polyethylene terephthalate tray+wrapping, vacuum packaging and then stored at $4^{\circ}C$. Changes in weight loss, color, firmness, microorganisms and sensory characteristics were measured. In general, the weight loss rate was increased slightly in vacuum packaged lotus roots. Application of heat treatment delayed browning of lotus roots, and especially vacuum packaged lotus roots were the most lowest ${\Delta}E$ value. However, L and ${\Delta}E$ value of PE film packaged lotus roots were increased highly during storage. The heat treated and vacuum packaging inhibited the growth of microorganisms effectively. The organoleptic quality of vacuum packaged lotus roots showed the best by sensory evaluation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.1
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• pp.78-84
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• 2009

In this paper, ZnO:Al thin film was deposited on polyethylene terephthalate(PET) substrate by capacitively coupled r. f. magnetron sputtering method from a ZnO target mixed with 2wt[%] Al2O3 to investigate the possible application of ZnO:Al film as a transparent conducting electrode for film typed DSCs. The effect of substrate bias on the electrical properties and film structure were studied. The results showed that a positive bias applied to the substrate during sputtering contributed to an improvement of electrical properties of the film by attracting electrons in the plasma to bombard the growing films. These bombardments provided additional energy to the growing ZnO:Al film on the substrate, resulting in significant variations in film structure and electrical properties. Electrical resistivity of the film decreases significantly as the positive bias increases up to +30[V] However, as the positive bias increases over +30[V], the resistivity decreases. The transmittance varies little as the substrate bias is increased from 0 to +60[V], and as r. f. powers increases from 160[W] to 240[W]. The film with electrical resistivity as low as $1.8{\times}10^{-3}[{\Omega}-cm]$ and optical transmittance of about 87.8[%] were obtained for 1,012[nm] thick film deposited with a substrate bias of +30[V].

• Journal of Mushroom
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• v.12 no.4
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• pp.287-292
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• 2014

This study investigated the packaging status and sensory quality of fresh-cut mushroom products from retail markets. Fifty one fresh-cut mushroom products were surveyed / purchased from discount stores in four cities in January (winter), March (spring), August (summer), and October (autumn) 2009. Collected fresh-cut mushrooms include single variety products like whole oyster mushroom and winter mushroom, diced or sliced oak mushroom, sliced king oyster mushroom, and ready-to-cook mixed mushroom products. Most fresh-cut mushrooms were packed in trays made of aluminum, polystyrene (PS), polyethylene terephthalate (PET), nylon materials covered with PVC (polyvinyl chloride) wrap or solid PP (polypropylene) and PS. Eighty nine percent of the covers were labeled with manufacture and expiration date. Collected samples showed severe browning (10%) and off-flavor (4%). The percentage of products with a rating of 'good' or better in overall quality was 90%. Moreover, Survey showed seasonal differences in sensory qualities. All of the collected fresh-cut mushrooms in autumn and winter had high marketability. However, Mushroom products collected in spring and summer had lower quality, hence requires treatment to prevent browning and off-flavor.

• Journal of Marine Bioscience and Biotechnology
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• v.9 no.1
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• pp.14-21
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• 2017

The purpose of this study was to inhibit biofouling on a selectively permeable membrane (SPM) and increase biomass productivity in marine photobioreactors (PBRs) for microalgal cultivation by chemical treatment. Surfaces of a SPM, composed of polyethylene terephthalate (PET), was sulfonated to decrease hydrophobicity through attaching negatively charged sulfonic groups. Reaction time of sulfonation was varied from 0 min to 60 min. As the reaction time increased, the water contact angle value of SPM surface was decreased from $75.5^{\circ}$ to $44.5^{\circ}$, indicating decrease of surface hydrophobicity. Furthermore, the water permeability of sulfonated SPM was increased from $5.42mL/m^2/s$ to $10.58mL/m^2/s$, which reflects higher nutrients transfer rates through the membranes, due to decreased hydrophobicity. When cultivating Tetraselmis sp. using 100-mL floating PBRs with sulfonated SPMs, biomass productivity was improved by 34% compared with the control group (non-reacted SPMs). In addition, scanning electron microscopic observation of SPMs used for cultivation clearly revealed lower degree of cell attachment on the sulfonated SPMs. These results suggest that sulfornation of a PET SPM could improve microalgal biomass productivity by increasing nutrients transfer rates and inhibiting biofouling by algal cells.

• Journal of the Korean Electrochemical Society
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• v.8 no.3
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• pp.139-145
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• 2005

[ $SnO_x$ ] films on the flexible substrate of PET film were prepared at ambient temperature under a $(CH_3)_4Sn(TMT: tetra-methyl tin)-H_2-O_2$ atmosphere in order to obtain transparent conductive polymer by using ECR-MOCVD(Electro Cyclotron Resonance Metal Organic Chemical Yfpor Deposition) system. The prepared $SnO_x$ thin films show generally over $90\%$ of optical transmittance at wavelength range of 380-780nm and about $1\times10^{-2\~3}ohm{\cdot}cm$ of electrical resistivity. In the present study, effects of $O_2/TMT\;and\;H_2/TMT$ mole ratio on the properties of $SnO_x$ films are investigated and the other process parameters such as microwave power, magnetic current power, substrate distance and working pressure are fixed. Based on our experimental results, the $SnO_x$ film composition ratio of Sn and O directly influences on the electrical and optical properties of the films prepared. The $SnO_x$ film with low electric resistivity and high transmittance could be obtained by controlling the process parameters such as $O_2/TMT\;and\;H_2/TMT$ mole ratio, which play an important role to change the composition ratio between Sn and O. An increase of $O_2/TMT$ mole ratio brought on the increases 0 content in the $SnO_x$ film. On the other hand, an increase of $H_2/TMT$ mole ratio lead to decreases the oxygen content in the film. The optimized composition ratio of oxygen : tin Is determined as 2.4: 1 at $O_2/TMT$ of 80 and $H_2/TMT$ of 40 mole ratio, respectively.

• Korean Journal of Environmental Agriculture
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• v.30 no.3
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• pp.281-287
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• 2011

BACKGROUND: According to Korean regulations, bottled waters (BWs) can not be treated with chemical disinfectants like chlorine, so UV and ozone disinfection is applied. During the past several years, chemicals were detected in some BWs, and the public was concerned about the safety of BWs. METHODS AND RESULTS: Mineral waters were stored for 180 days at $25^{\circ}C$ and $50^{\circ}C$, tested acetaldehyde and formaldehyde by HPLC. When mineral waters were put in a PET bottles, the formaldehyde level ranged from 5 to $66{\mu}g/L$ during 180 days at $50^{\circ}C$. While the acetaldehyde level ranged from 31 to $221{\mu}g/L$, it was low than $16{\mu}g/L$ in glass bottle. CONCLUSION(s): This result showed that formaldehyde and acetaldehyde were detected higher in PET bottles than glass bottles, these also increased depending on the time of storage. Concentration of formaldehyde and acetaldehyde could be significantly influenced by the time of storage and temperature.

• Horticultural Science & Technology
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• v.31 no.2
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• pp.186-193
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• 2013

Potential of consumer unit packaging was investigated for quality maintenance during export simulation in king oyster mushrooms (Pleurotus eryngii). Mushrooms were harvested in late May, precooled to $4^{\circ}C$ within 6 hours, and then packaged for shipping in two ways: 2 kg bulk packaging in a polyethylene (PE) bag or three types of unit packaging methods such as 400 g in polypropylene film bag (PPB), 200 g on styrofoam tray + PE shrinkage film wrapping (STW), and 200 g in polyethylene terephthalate (PET) containers (PETC). For local distribution of bulk-packaged commodity, mushrooms were sorted again and packaged into 3 consumer units in the same way as for the initial shipping packages. Simulation of refrigerated container shipping was performed in a walk-in type pilot storage at $0.5^{\circ}C$ for 5 weeks, while local marketing simulation was carried out on the shelf at $7^{\circ}C$ for 7 days. During the shipment simulation, creation of modified atmosphere (MA) was substantial in 2 kg bulk packages with low $O_2$ below 2% and high $CO_2$ over 15% whereas, in PPB and PETC unit packages, relatively higher $O_2$ concentrations were observed. On the shelf at $7^{\circ}C$, $CO_2$ concentrations rapidly increased in PPB and PETC packages despite the short marketing period. Overall marketability evaluated by off-flavor, browning, and texture rating was maintained at excellent level when 2 kg bulk packaging in PE or unit packaging in PPB and PETC were used for shipment. In contrast, establishment of MA was very slight in STW packages during shipment and local distribution resulting in poor quality after export simulation. The results suggested that shipment using adequate consumer unit packaging is more practical and economically beneficial than using bulk packaging in the export program consisting of 5-week shipment and 7-day local distribution.

• Korean Journal of Food Science and Technology
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• v.47 no.1
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• pp.63-69
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• 2015

The aim of this study was to investigate the deformation of packaging materials used for ready-to-eat (RTE) foods after the retort process and microwave heating. From the multilayer films consisting of polyethylene terephthalate (PET), polyamide (PA), and cast polypropylene (CPP) in a stand-up pouch form used for RTE foods, some deformation of the CPP layer, which was in direct contact with the food, was observed after the retort process and microwave heating. The damage was more severely caused by microwave heating than by the retort process. This may be attributed to diverse factors including the non-uniform heating in a microwave oven, the sorption of oil into the packaging film, and the different characteristics of food components such as viscosity, salt and water content. The development of heat-resistant packaging materials and systems suitable for microwave heating of RTE foods is required for the safety of consumers.