• Journal of Korean Society on Water Environment
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• v.37 no.5
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• pp.381-397
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• 2021

Off-flavor materials (geosmin and 2-methylisoborneol (2-MIB)) produced by microorganisms, such as, cyanobacteria and actinomycetes, cause freshwater use problems worldwide. Due to unpleasant taste and odor, these microorganisms have raised issues especially in drinking water resources. Recently, there has been increasing concern about 2-MIB and causal cyanobacteria, namely, Pseudanabaena, in Korea. However, material production and ecological dynamics remain largely unexplored. This study reviewed the distribution of Pseudanabaena, its species diversity, and the research trend of molecular ecology related to 2-MIB production in Korea. Based on published literature, we found that seven species of Pseudanabaena which include P. mucicola, P. limnetica, P. redekei, P. catenata, P. galeata, P. yagii, and P. cinerea appeared to occur in a variety of Korean water systems. All of these Pseudanabaena species were found in the North-Han River system (Lakes Soyang, Chuncheon, Uiam, and Paldang). Some of these species were also detected in other watersheds, but the precise species diversity was not identified. Species belonging to the Pseudanabaena genus are hard to classify through general microscopic alpha taxonomy, due to their very small cell size and similar morphological characters. Moreover, the potential of 2-MIB production cannot be detected by microscopic observation. Combining molecular ecological techniques, such as, environmental genomic materials (eDNA, eRNA) analyses to conventional methods could be useful to better understand the off-flavor material production and dynamics, thereby providing more efficient management strategies of freshwater systems.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.12 no.2
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• pp.91-96
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• 2006

The widespread use of packaging materials on food packages sometimes causes off-flavor and deterioration in the food by migration of packaging materials which consist of mainly plastic materials and printing ink solvents. Even though migration of the residual packaging materials does not generally cause safety problems in the contained food, it certainly can generate off-flavor and finally deteriorate quality of the finished product. In highly consumer-oriented markets, quality of the finished product is gaining more importance economically, so profound and thorough study about migration into food to maintain the fine quality of the end product becomes an importance issue. Studies have been conducted about migration of various packaging materials and the chemical reactions between the food components and the materials used for food packaging (Brody, 1989; Mcneal and Breder, 1987; Lawson, G and Lawson, C, 1996). Several of these studies have measured partition coefficient values (Kp) between packaging materials and various food samples and involved finding factors that affected the partitioning behavior of packaging materials into the contained food. However, to enable prediction of partitioning, data are still needed on the relation of packaging material chemical structure and properties to partitioning behavior, and on the partitioning behavior of various food ingredients and the total food compositions.

• Food Science of Animal Resources
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• v.23 no.2
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• pp.122-127
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• 2003

A surimi like material was made from fresh pig hearts and used to manufacture emulsion-type sausages for the improvement of quality characteristics. The heart muscles were diced and frozen at -60$^{\circ}C$ until processed. Then, the frozen diced heart muscles were thawed, chopped, filtered, and washed to extract myofibrillar proteins. The residue was centrifuged to take a surimi-like material. Emulsion-type sausages were made different levels of surimi-like material(5∼15%) and compared to the control. Cooking loss(CL, %) and water-holding capacity (WHC, %) were measured on raw meat batter, whereas shear force, hardness, color and panel test were measured after cooking. The addition of the surimi-like material up to 15% level in the sausage formulation reduced CL and increased WHC, as compared to the control. Shear force and hardness values of the control had the highest value, however sausages containing 15% surimi-like material had the lowest value(p<0.05). Increased surimi-like material became darker in color. Although no differences in panel scores of flavor and off-flavor were observed, panellists prefer to select sausages having 15% surimi-like material(p<0.05). These results indicated that a surimi-like material, which was a myofibrillar protein extracted from pig hearts, could be used to manufacture emulsion-type sausage up to 15% to improve cooking yield and textural characteristics without color and flavor defects.

• Journal of Life Science
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• v.24 no.12
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• pp.1325-1329
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• 2014

Gugija (Lycii chinese Miller) is traditionally consumed as a Chinese medicinal material in food, tea, or alcoholic beverages. Gugija has beneficial healthy components, but it produces an off-flavor during storage. This study compared the flavor components of fresh-dried Gugija and stale-dried Gugija. The flavor compounds in one fresh sample (sample 1) and one stale sample (sample 2) were extracted by the simultaneous distillation and extraction method. The concentrated aroma extracts were analyzed and identified by gas chromatography-mass spectrometry. Forty-five compounds, including 17 aldehydes, 8 alcohols, 6 terpene compounds, 4 esters, 3 ketones, and 3 pyrazines, were isolated in sample 1. Thirty-four compounds, including 12 aldehydes, 3 alcohols, 5 terpene compounds, 2 esters, 3 ketones, 3 pyrazines, and 1 acid, were isolated in sample 2. The main aroma components of sample 1 were 2-methyl butanal, 2-methyl propanol having sweet odor, and hexanal, (Z)-3-hexenol having grass odor, and phenyl acetaldehyde, benzyl alcohol having floral odor, and alkyl pyrazines having nutty odor. These compounds were decreased in sample 2, and several compounds containing isovaleric acid, which has a disagreeable, rancid-cheese odor were found newley.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.27 no.2
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• pp.55-62
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• 2021

This study aims to reduce the rancid odor generated during the fermentation process of kimchi by inserting zinc oxide (ZnO) into an inorganic porous material with a high surface area to decompose or adsorb the fermentation odor. ZnO activated by the presence of moisture exhibits decomposition of rancid odors. Mixed with Titanium dioxide (TiO₂), a photocatalyst. To manufacture the packaging liner used in this study, NaOH, ZnCl₂, and TiO₂ powder were placed in a tank with diatomite and water. The sludge obtained via a hydrothermal ultrasonication synthesis was sintered in an oven. After being pin-milled and melt-blended, the powders were mixed with linear low-density polyethylene (L-LDPE) to make a masterbatch (M/B), which was further used to manufacture liners. A gas detector (GasTiger 2000) was used to investigate the total amount of sulfur compounds during fermentation and determine the reduction rate of the odor-causing compounds. The packaging liner cross-section and surface were investigated using a scanning electron microscope-energy dispersive X-ray spectrometer (SEM-EDS) to observe the adsorption of sulfur compounds. A variety of sulfur compounds associated with the perceived unpleasant odor of kimchi were analyzed using gas chromatography-mass spectrometry (GC-MS). For the analyses, kimchi was homogenized at room temperature and divided into several sample dishes. The performance of the liner was evaluated by comparing the total area of the GC-MS signals of major off-flavor sulfur compounds during the five days of fermentation at 20℃. As a result, Nano-grade inorganic compound liners reduced the sulfur content by 67 % on average, compared to ordinary polyethylene (PE) foam liners. Afterwards SEM-EDS was used to analyze the sulfur content adsorbed by the liners. The findings of this study strongly suggest that decomposition and adsorption of the odor-generating compounds occur more effectively in the newly-developed inorganic nanocomposite liners.

• Korean Journal of Food Science and Technology
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• v.52 no.5
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• pp.524-528
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• 2020

The aim of this study was to enhance the use of wheat bran in lactic acid bacteria (LAB) fermentation. LAB fermentation of wheat bran and the flavor components and amino acids of fermentation products were analyzed using gas chromatography-mass spectrometry (GC/MS) and high-performance liquid chromatography (HPLC). The results showed that total flavor components increased by 93% and 73% in the animal-based LAB mixture (T2) and plant-based LAB mixture (T3), respectively, after fermentation. Among these components, 2,3-butanedione (diacetyl), known for its buttery flavor, was detected at concentrations of 18.44 ng/g (T2) and 16.95 ng/g (T3). Levels of hexanal and nonanal, which causes off-flavor components in wheat bran, dramatically decreased after T2 fermentation; similarly, levels of total free amino acids decreased by 37.6% (T2) and 36.7% (T3) after fermentation. This may explain why some components were bound to volatile compounds during LAB fermentation. These results suggest that LAB-fermented wheat bran is a potential value-added food material.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.9
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• pp.1347-1353
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• 2006

Effects of microencapsulated chitooligosaccharide addition in milk were evaluated by determination of the efficiency of microencapsulation, cholesterol removal, color, viscosity and sensory properties. Coating material was polyglycerol monostearate (PGMS) and the efficiency of microencapsulation was 88.08% at a 10:1 ratio of coating to core materials (w/w). When 0.5% of microencapsulated chitooligosaccharide was added into milk, the color values (L, a, and b) and viscosity were significantly different from those of noncapsulated chitooligosaccharide-added groups (p<0.05). The release of chitooligosaccharide from microcapsules was 7.6% in milk at $4^{\circ}C$ for 15-day storage. In both 0.5 and 1.5% microencapsulation addition, the scores of all sensory characteristics except for off-flavor were significantly different between encapsulated chitooligosaccharide and noncapsulated chitooligosaccharide-added groups during all periods of storage. The present study indicated that chitooligosaccharide microcapsules could be applicable into commercial milk with little adverse effects on physical and sensory properties.

• Korean Journal of Food Science and Technology
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• v.27 no.6
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• pp.852-859
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• 1995

Vacuum cooling were carried out for freshness keeping of shiitake mushroom. Shiitake mushroom was cooled within 30 minutes from $20.5^{\circ}C$ to $0.5^{\circ}C$ by vacuum cooling, and then temperature drop of $6.6^{\circ}C$ per weight loss of 1% was taken place during precooling. Weight loss, surface discoloration and softening were reduced by precooling. Judging from organoleptic properties such as cap opening, discoloration, texture and off-flavor, shelf-life of precooled mushroom was lengthed by 20% than that of non-treated mushrooms. Considering effect of packing material on freshness of shiitake mushroom after precooling, weight retention, hardness and organoleptic properties of mushroom packed with PVC wrap were superior to those packed in carton box.

• The Korean Journal of Food And Nutrition
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• v.23 no.2
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• pp.218-225
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• 2010

To make sponge cake using Lentinus edodes powder, which is useful and valuable as a functional food material, we tested samples with 3, 6, 9, and 12% L. edodes powder to ascert200ain the quality characteristic and make optimize preparation. Samples and L. edodes powder-free control sponge cakes were compared in terms of quality characteristics including batter viscosity and specific gravity, moisture content, volume index, weight, color, textural characteristics, and sensory qualities, to determine the optimal ratio of L. edodes powder in the formulation. Viscosity and specific gravity of sample and control batter were not significantly different. Moisture content of the sample and control sponge cake also did not differ significantly, and weight of sample and control sponge cakes did not differ appreciably. The volume index of the samples displayed contrasting values, increasing with 3~6% L. edodes powder and decreasing with 9~12% powder. L, a, and b crust color values of samples sponge cakes were lower than those of control cakes. The L and a values of the control cakes was maximal, with values progressively decreasing with incorporation of more L. edodes powder. The b value decreased by 3% with the addition of up 6% L. edodes powder with no further decrease thereafter. L. edodes powder was the lower value. So was the color a, and L. edodes powder increased, a-values decreased. 3% difference was shown in b, the color and none between the samples with 6~12%. L. edodes powder showed lower values making a comparison with the control. Hardness and fracturablility were not appreciably affected by 3% L. edodes powder, but was affected by concentrations 6%. Fracturability og sample sponge cakes was consistently lower than control cakes. Fracturability made little difference in 3% samples, but it was not the same with more than 6% L. edodes powder samples; the samples showed lower value than the control. Adhesiveness was not significantly affected. Chewiness was lower in all sample cakes except those prepared with 3% L. edodes powder. Use of L. edodes powder conferreds higher resilience values as compared to thecontrols. Sensory attributes of color, flavor, softness and overall acceptability were the highest in control sponge cakes, as the amount of L. edodes powder increased, the acceptability decreased. L. edodes-flavor, pleasant taste and off-flavor were the lowest in control cakes, and values increased as the amount of L. edodes powder increased. The control sponge cakes showed the highest values in egg-flavor and moistness, which progressively increased as added L. edodes powder increased. The results indicate that control sponge cakes displayed were. the highest overall acceptability, with acceptability decreasing and it decreased as L. edodes powder content increased. However, 3~6% L. edodes powder can produce an acceptable product, and may be used as anoptimized mixture ratio.

• Horticultural Science & Technology
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• v.28 no.6
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• pp.980-984
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• 2010

Research regarding respiration rate, off-flavor related material and freshness maintenance effect of active MA mini-packaging on perilla leaves has been carried in this study. Respiration rate was highly maintained at high oxygen treatments ($CO_2:O_2:N_2$=0:30:70 and 0:50:50), higher than non-treatment and low oxygen treatments (6:2:92, 0:10:90) during the storage period, and ethylene production was relatively higher. However, off-flavor related materials, acetaldehyde and ethanol production was noticeably low. Weight losses of non-treatment and low-oxygen treatment were about 1.8 and 1.4%, respectively. At the fifth day of storage there was no weight loss. Ascorbic acid content was 13.3 mg/100 g F.W. at the first day of storage. At the third day of storage non-treatment showed the lowest value of ascorbic acid, 8.8 mg/100 g F.W. Ascorbic acid content of active MA treatment gradually decreased without a striking difference as the storage day extended. Chlorophyll content was the lowest at the fifth day of storage with non-treatment, 47.5 (SPAD-502 unit) while the active MA treatment maintained high level of chlorophyll content, 53.0. Sensory evaluation (vision) showed that marketability gradually decreased but was maintained in high oxygen treatments (0:30:70 and 0:50:50), even at the fifth day of storage. Occurrence of off-flavor in non-treatment at the fifth day of storage was extremely low, 2.6; whereas high in high oxygen treatment, 3.4. Active MA packaging maintained freshness two more days at room temperature (about $27^{\circ}C$).