• Korean Journal of Microbiology
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• v.47 no.1
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• pp.22-29
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• 2011

Rhodopsin is a membrane protein with seven transmembrane region which contains a retinal as its chromophore. Although there have been recently reports on various photo-biochemical features of rhodopsins by a wide range of purifying and measurement methods, there was no actual comparison related to the difference of biochemical characteristics according to their physical environment of rhodopsins. First, proteorhodopsin (PR) was found in marine proteobacteria whose function is known for pumping proton using light energy. Second one is Anabaena sensory rhodopsin (Nostoc sp.) PCC7120 (ASR) which belongs to eubacteria acts as sensory regulator since it is co-expressed with transducer 14 kDa in an operon. In this study, we applied two types of rhodopsins (PR and ASR) to various environmental conditions such as in Escherichia coli membranes, membrane in acrylamide gel, in DDM (n-dodecyl-${\beta}$-D-maltopyranoside), OG (octyl-${\beta}$-D-glucopyranoside), and reconstituted with DOPC (1,2-didecanoyl-sn-glycero-3-phosphocholine). According to the light-induced difference spectroscopy, rhodopsins in 0.02% DDM clearly showed photointermediates like M, and O states which respond to the different wavelengths, respectively and showed the best signal/noise ratio. The laser-induced difference spectra showed the fast formation and decay rate of photointermediates in the DDM solubilized samples than gel encapsulated rhodopsin. Each of rhodopsins seemed to be adapted to its surrounding environment.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.3
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• pp.224-231
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• 2019

This study investigated the physicochemical, microbiological, antioxidant, and sensory characteristics of Makgeolli supplemented with 10, 20, and 30% Codium fragile (Cf) during an 8-day fermentation period. The pH and acidity on day 0 were lower in Makgeolli supplemented with Cf (pH 3.55-3.65, acidity 0.26-0.29%) than in the unsupplemented Makgeolli (control) (pH 3.72, acidity 0.23%). The pH and acidity of Cf Makgeolli on day 8 were 3.08-3.12 and 0.67-0.75%, respectively. The sugar content increased steadily until day 4 (8.1-8.5 Brix) and then decreased steadily (6.5-6.8 Brix). The alcohol content increased steadily until day 8 (13.2-14.3%). The pH decreased, acidity increased, and alcohol content increased significantly (all P<0.05), with stepwise increases in fermentation time and Cf concentrations. The lactic acid bacteria counts were 9.28-9.37 log versus 8.18 log in the control. The DPPH (1,1-diphenyl-2-picrylhydrazyl) and ABTS [2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)] radical scavenging activities were higher in Cf Makgeolli (DPPH 74.63-84.64%, ABTS 51.01-64.79%) than in the control (DPPH 30.97%, ABTS 21.21%). Makgeolli supplemented with 10 and 20% Cf had the highest taste, smell, and overall acceptance scores. This study suggests that Makgeolli supplemented with 10 and 20% Cf could be developed due to its good physicochemical and microbiological characteristics, including high antioxidant properties and good consumer acceptance.

• Food Science of Animal Resources
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• v.27 no.3
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• pp.377-381
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• 2007

The aim of this study was to evaluate the microbial safety and quality changes of Korean sliced pork jerky, and to investigate these properties over 90 days and 28 days of storage at room temperature $(25^{\circ}C)$ and elevated temperature $(35^{\circ}C)$. Based on the microbial counts of pork jerky, mesophilic bacteria were detected at 2.50 log CFU/g at day 0. The mesophilic bacterial count did not change significantly for all samples, and coliform bacteria and Bacillus cereus were not detected in any samples during storage at either $25^{\circ}C\;or\;35^{\circ}C$. The following physicochemical qualities were also investigated: TBA value, Aw, and pH. In the case of $25^{\circ}C$ storage, the Aw of Korean sliced pork jerky was 0.72 at day 0, and was reduced to 0.58 after 90 days of storage. The TBA value increased as the storage time increased, and was 0.52 after 90 days of storage. The pH of all samples did not change significantly. In the case of $35^{\circ}C$ storage, the TBA, Aw, and pH values were not significantly different from those obtained during $25^{\circ}C$ storage. In addition, the sensory properties of all samples were not significantly different between storage at the two temperatures. In conclusion, these results suggest Korean sliced pork jerky could be used to study the development of commercial pork jerky.

• Food Science of Animal Resources
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• v.27 no.1
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• pp.42-46
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• 2007

We evaluated the microbial safety and quality characteristics of Korean slice beef jerky, and investigated these properties over 28-day and 90-day storage periods at room temperature ($25^{\circ}C$) and elevated temperature ($35^{\circ}C$). After microbial counts of all samples, mesophilic bacteria were detected at 1.23 Log CFU/g at day 0. Counts of mesophilic bacteria did not change significantly in all samples, and coliforms and Bacillus cereus were not detected in all samples during storage at either $25^{\circ}C$ or $35^{\circ}C$. TBA values, Aw, and pH were investigated. The Aw of korean slice beef jerky stored at room temperature was 0.71 at day 0, and was reduced to 0.61 after 90 days. The TBA value increased as storage time increased, and its TBA value was 0.48 after 90 days of storage. The pH of all samples did not change significantly. At $35^{\circ}C$ storage, TBA values, Aw, pH were not significantly different than those stored at $25^{\circ}C$. Also, the sensory properties of all samples were not significantly different between two storage temperatures. In conclusion, these results suggest Koran slice beef jerky ould be used as basic study for development of the commercial beef jerky.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.6
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• pp.990-997
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• 1995

Effect of preparation method on Yulmoo kimchi(watery kimchi prepared with Yulmoo, leaf radish) fermentation was investigated by measuring physicochemical, microbiological and sensory properties for 20 days. Yulmoo kimchi was fermented at 4$^{\circ}C$ after keeping at room temperature(27$\pm$0.5$^{\circ}C$) for 8 hours. Four types(A, B, C, D) of Yulmoo kimchi were prepared. Sample A was made without wheat flour paste and red pepper powder and sample B was made with wheat flour paste. Sample C was made with red pepper powder, and sample D was made with wheat flour paste and red pepper powder. pH was slowly lowered and stabled after 10 days in all samples. Total acid content increased in all samples. Reducing sugar content initially increased and decreased thereafter. Especially, reducing sugar content of sample B increased in the early stage of fermentation and maintained initial reducing sugar content after 20 days. Total vitamin C content reduced during fermentation in all samples. Especially initial total vitamin C content of sample D increased more than those of other samples relatiely. Lightness and yellowness showed no difference, but on the other hand redness increased gradually in all samples. The number of lactic acid bactgeria reached maximum value in 10~13 days with the total cell numbers and gradually decreased thereafter in all samples. The number of lactic acid bacteria and total cell number of sample D was much more than those of any other samples. As a result of the sensory evaluation, Yulmoo kimchi showed significant difference in all characteristics. Sample D showed the highest scores in all characteristics before 10 days of fermentation. However, after 10 days sample B showed the highest scores.

• Korean journal of food and cookery science
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• v.15 no.2
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• pp.178-184
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• 1999

Physicochemical, microbiological, and sensory properties of corns irradiated by gamma-ray at 1.2 kGy, 10.1 kGy or 30.5 kGy were investigated every 40 days during the storage at 25$^{\circ}C$ and 50% relative humidity. The moisture content of irradiated corns decreased and crude lipid content increased during the storage. Acid values of the irradiated corns were not significantly different from those of the nonirradiated corns but acid values generally increased during the storage. TBA values of irradiated corns increased in proportion to the irradiation dose and to the storage period. Numbers of mesophilic and psychrotrophic bacteria in the nonirradiated corns and 1.2 kGy dose-irradiated corns were higher than those in the corns irradiated at 10.1 kGy and 30.5 kGy at the late storage. The number of yeasts and molds in the nonirradiated corns were higher than those in the irradiated corns during the storage. In Hunter's color, L values of irradiated and nonirradiated corns decreased with the storage period and b values of all groups decreased except the group irradiated at 30.5 kGy. In sensory evaluation, fresh corn odor of the irradiated group was significantly different from those of the nonirradiated one stored for only 0 day and 200 days but raw corn odor and acidic odor were not significantly different among the groups depending upon the radiation dose and storage period.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.2
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• pp.330-335
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• 1995

The purpose of this study was to investigate the effects of onion on the physicochemical, microbiological and sensory properties of Dongchimi. Dongchimi with levels(0, 5, 10, 20%) of onion was fermented at twodifferent temperatures : Group A was fermented at 4$^{\circ}C$ and group B was fermented at 4$^{\circ}C$ after fermentation at room temperature(27$\pm$0.5$^{\circ}C$) for 24 hours. During the fermentation up to 45 days, total acidity increased while pH decreased gradually. Total acidity of group B was relatively higher than that of group A. The content of reducing sugar was reached the maximum value in 6 days of fermentation in the group A and on 3 days in the group B. Especially, the highest content of reducing sugar was shown on the Dongchimi added with 5% onion in the group A and 20% onion in the group B. Vitamin C was reduced in the early stage of fermentation, and increased gradually after 10 days. However, vitamin C of Dongchimi without onion increased rapidly in the early stage of fermentation and remarkably decreased thereafter. After 20 days, vitamin C was maintained in Dongchimi added with 10% onion of both two groups. The number of lactic acid bacteria was reached the maximum value on 1 day in the Dongchimi without onion and on 3 days in the Dongchimi added 5, 10 and 20% onion of group A, while gropu B was reached on 1 days and then decreased thereafter. As a result of the sensory evaluation, Dongchimi added 5% onion in the group A showed the highest scores in texture and overall acceptability. Whereas, in the group B, Dongchimi added 20% onion was the most preferable one.

• Microbiology and Biotechnology Letters
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• v.44 no.2
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• pp.150-155
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• 2016

This study investigated the effects of combined treatments of immersion liquid and high hydrostatic pressure (HHP, 100−400 MPa) on the quality of mackerel. In this study, we measured viable cell counts, pH level, color value, texture properties, and sensory evaluation of mackerel. Viable cell counts of mackerel treated with combined HHP were decreased by 2 log cycles at 300 MPa and 400 MPa compared to the control. The pH values of mackerel treated with HHP at 300 MPa and 400 MPa were higher than that of other samples. Hardness, gumminess, and chewiness decreased when treated with combined HHP and increased with increase in HHP. Lightness and whiteness of mackerel increased, but redness decreased, with increase in HHP. In case of sensory evaluation, texture of mackerel treated with HHP at 300 MPa and 400 MPa showed higher scores than that of other samples. These results suggest that immersion liquid and HHP treatments can increase microbiological safety and improve textural properties of mackerel.

• Fisheries and Aquatic Sciences
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• v.20 no.7
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• pp.13.1-13.7
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• 2017

In order to evaluate the maximal storable period of the raw crab for a non-thermal muscle separation, the quality changes of the leg meat of red snow crab (Chionoecetes japonicus) during freeze storage were investigated. Fresh red snow crabs were stored at $-20^{\circ}C$ for 7 weeks, and the leg muscle was separated by a no heating separation (NHS) method every week. During the storage, considerable loss of the leg muscle did not occur and microbiological risk was very low. In contrast, discoloration appeared at 2-week storage on around carapace and the leg muscle turned yellow at storage 3-week. In physiochemical parameters, protein and free amino acids gradually decreased with storage time, expected that proteolytic enzymes still activated at $-20^{\circ}C$. At 4-week storage, the sensory acceptance dropped down below point 4 as low as inedible and notable inflection points in pH and acidity were observed. The volatile base nitrogen was low, though a little increase was recorded. These results suggested that the maximal storable period at $-20^{\circ}C$ of the raw material was within 2 weeks and it was depended on external factor such as the discoloration. The present study might be referred as basic data for approaches to solve quality loss occurred in non-thermal muscle separation.

• Food Science of Animal Resources
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• v.33 no.2
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• pp.205-213
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• 2013

The objective of this study was to evaluate the quality characteristics of sun-dried Hanwoo beef jerky added with Salicornia herbacea (SH). Sliced Hanwoo beef shank were marinated and sun-dried at $28-30^{\circ}C$, relative humidity (RH) 30-35% for 3.5 h. The physicochemical and microbiological traits of the Hanwoo beef jerky were analyzed during the aerobically packaged storage at $25^{\circ}C$. The water activities of beef jerky with 0.5% and 1.0% SH were lower than those of the control at 0 d (p<0.05). The pH values of beef jerky with SH were significantly higher than those of the control (p<0.05). The beef jerky with SH and ascorbic acid showed significantly lower TBARS values than the control (p<0.05). The beef jerky with SH showed a significantly lower redness ($a^*$) than the control (p<0.05). Total plate count (TPC) of beef jerky with 1.0% SH was significantly lower than that of the control during the storage of 20 d (p<0.05). Yeast/mold was detected in the control and beef jerky with SH after storage periods of 10 and 20 d, but was not detected in jerky with ascorbic acid. With regard to the sensory properties, beef jerky with SH showed significantly greater flavor scores than the others (p<0.05). The result shows that SH powder can be used to increase the sensory quality and microbial safety of beef jerky.