• Animal Bioscience
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• v.36 no.10
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• pp.1596-1603
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• 2023

Objective: Sous-vide cooking offers several advantages for poultry meat, including enhanced tenderness, reduced cooking loss, and improved product yield. However, in duck meat, there are challenges associated with using the sous-vide method. The prolonged cooking time at low temperatures can lead to unstable microbial and oxidative stabilities. Thus, we aimed to assess how varying sous-vide cooking temperatures and durations affect the physicochemical and microbial characteristics of duck breast meat, with the goal of identifying an optimal cooking condition. Methods: Duck breast meat (Anas platyrhynchos) aged 42 days and with an average weight of 1,400±50 g, underwent cooking under various conditions (ranging from 50℃ to 80℃) for either 60 or 180 min. Then, physicochemical, microbial, and microstructural properties of the cooked duck breast meat were assessed. Results: Different cooking conditions affected the quality attributes of the meat. The cooking loss, lightness, yellowness, Hue angle, whiteness, and thiobarbituric acid reactive substance (TBARS) values of the duck breast meat increased with the increase in cooking temperature and time. In contrast, the redness and chroma values decreased with the increase in cooking temperature and time. Cooking of samples higher than 60℃ increased the volatile basic nitrogen contents and TBARS. Microbial analysis revealed the presence of Escherichia coli and Coliform only in the samples cooked at 50℃ and raw meat. Cooking at lower temperature and shorter time increased the tenderness of the meat. Microstructure analysis showed that the contraction of myofibrils and meat density increased upon increasing the cooking temperature and time. Conclusion: Our data indicate that the optimal sous-vide method for duck breast meat was cooking at 60℃ for 60 min. This temperature and time conditions showed good texture properties and microbial stability, and low level of TBARS of the duck breast meat.

• Food Science of Animal Resources
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• v.34 no.6
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• pp.808-814
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• 2014

This study investigated the effect of gum arabic (GA) combined with microbial transglutaminase (TG) on the functional properties of porcine myofibrillar protein (MP). As an indicator of functional property, heat-set gel and emulsion characteristics of MP treated with GA and/or TG were explored under varying NaCl concentrations (0.1-0.6 M). The GA improved thermal gelling ability of MP during thermal processing and after cooling, and concomitantly added TG assisted the formation of viscoelastic MP gel formation. Meanwhile, the addition of GA decreased cooking yield of MP gel at 0.6 M NaCl concentration, and the yield was further decreased by TG addition, mainly attributed by enhancement of protein-protein interactions. Emulsion characteristics indicated that GA had emulsifying ability and the addition of GA increased the emulsification activity index (EAI) of MP-stabilized emulsion. However, GA showed a negative effect on emulsion stability, particularly great drop in the emulsion stability index (ESI) was found in GA treatment at 0.6 M NaCl. Consequently, the results indicated that GA had a potential advantage to form a viscoelastic MP gel. For the practical aspect, the application of GA in meat processing had to be limited to the purposes of texture enhancer such as restructured products, but not low-salt products and emulsion-type meat products.

• Korean Journal of Food Science and Technology
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• v.26 no.2
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• pp.167-171
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• 1994

With a view to improving microbiological quality of spinach powder which is currently used for convenience food production, comparative efficacy of ethylene oxide(EO) fumigation and gamma irradiation was investigated by determining microbial populations and physicochemical quality for treated samples. Spinach powder was contaminated with various microorganisms ranging from $10^{2}/g\;to\;10^{4}/g$, which composed of thermophiles, acid tolerant bacteria, fungi, coliforms, etc. Microorganisms contaminated were destroyed up to undetected levels by gamma irradiation at below 7 kGy. showing the radiosensitivity $D_{10}$ 2.93 kGy on total aerobic bacteria. Ethylene oxide fumigation, however. was found unsatisfactory for physicochemical quality as well as microbial decontamination of the sample. It has been generally observed that influence of optimum-dose range of irradiation on the physicochemical qualities was insignificant, which was proved in the organoleptic evaluations on the stored sample.

• The Korean Journal of Food And Nutrition
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• v.29 no.6
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• pp.849-859
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• 2016

Edible insects have gained recognition worldwide as complementary protein sources. Recently, four edible insects were newly allowed to be used as food materials in Korea: the mealworm (Tenebrio molitor), the cricket (Velarifictorus asperses), the white-spotted flower chaffer beetle larva (Protaetia brevitarsis seulensis), and the rhinoceros beetle larva (Allomyrina dichotoma). In this study, we evaluated the oxidative stabilities of these four edible insects during cold storage. The insects were sacrificed by blanching for 3 minutes in boiling water. The blanched insects were then stored at $4^{\circ}C$ in an incubator for 42 days. The color values, titratable acidity, peroxide values, acid values, TBARS, contents of VBN, and total plate counts of the insects were measured at days 0, 2, 4, 7, 10, 14, 21, 28, 35, and 42, respectively. Blanching decreases oxidative stresses during storage. At day 0, the white-spotted flower chaffer beetle larva showed the highest values for acid value, TBARS, VBN, and microbial counts. Most of the oxidative indicators were significantly changed at day 14 in all four insects, possibly related with the growth on all microbial plates. Based on microbial safety and the oxidative stabilities of lipids and proteins, optimal storage conditions for the cricket, the white-spotted flower chaffer beetle larva, and the rhinoceros beetle larva were 10~14 days at $4^{\circ}C$. Likewise, the mealworm showed rapid oxidation after day 14, but poor qualities were not observed until day 28.

• Journal of the Korean Society of Food Culture
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• v.36 no.3
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• pp.325-332
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• 2021

This study sought to investigate the effects of heat-moisture treatment (HMT) and ethanol treatment (EOH) for improving the quality and storage stability of Tteokbokki Tteok. The quality characteristics were evaluated by moisture, pH, color, texture profile analysis, and observing the microbial properties after the heat-moisture treatment or ethanol treatment. As the storage period increased, the moisture content of Tteokbokki Tteok tended to decrease except for the HMT group (p<0.05) while the pH did not show significant variation except for the EOH group (p<0.05). While measuring the color, the L-value tended to increase in all groups during the storage period. The a-value and the b-value showed the highest values in the HMT group and the control (CON) group, respectively. In the texture profile analysis, all groups showed a significant tendency to increase levels of hardness and chewiness as the storage period increased (p<0.05). The HMT group showed an increase in hardness and adhesiveness, which are characteristics of the HMT treatment. The results of examining the microbial properties of Tteokbokki Tteok showed that the total microbial count in the HMT group was 4.52 on the 8^th day of storage, which was lower than the level in the CON group and the EOH group on the 4^th day of storage. Yeast and mold were not measured during the storage period. Thus the results of this study showed that when manufacturing Tteokbokki Tteok, the heat-moisture treatment of rice powder increased the storage stability by delaying microbial growth and also had positive effects on quality.

• Korean journal of food and cookery science
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• v.25 no.3
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• pp.297-305
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• 2009

This study aimed to determine the physicochemical, microbiological, and sensory qualityies of steamed chicken samples by prepared with combined additions of oregano-allspice and Ascorbic acid (OA/AA), and processed by a sous-vide cook - chill system. The hurdle effect of the OA/AA addition was examined in terms of microbial stability improvements and their effects on sensory were also evaluated. First, the microbial risk was lowered and chicken quality was good with the addition of the OA/AA hurdle as compared to the control. Second, over various days of storage, the microbial quality of the OA/AA samples was relatively high. In standard plate counts, the control group presented a bacteria level of 2.75 LogCFU/g at 10 days of storage, but the OA/AA groups were had counts of 2.38, 1.89 and 1.81 LogCFU/g, respectively. And at 15 days of storage, the control group had a level of 3.65 LogCFU/g whereas the OA/AA groups had counts of 3.55, 3.54, and 3.24 LogCFU/g, respectively. Lastly, the sensory scores of the OA/AA groups were higher than those of the control group. Accordingly, overall microbial and sensory characteristics were better in the OA/AA hurdle groupsf than in the control group. Thus, the combined addition of Oregano-allspice and Ascorbic acid may be and alternative means for extending shelf - life.

• Journal of Microbiology and Biotechnology
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• v.22 no.1
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• pp.34-45
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• 2012

A thermophilic Bacillus stearothermophilus F1 produces an extremely thermostable serine protease. The F1 protease sequence was used to predict its three-dimensional (3D) structure to provide better insights into the relationship between the protein structure and biological function and to identify opportunities for protein engineering. The final model was evaluated to ensure its accuracy using three independent methods: Procheck, Verify3D, and Errat. The predicted 3D structure of F1 protease was compared with the crystal structure of serine proteases from mesophilic bacteria and archaea, and led to the identification of features that were related to protein stabilization. Higher thermostability correlated with an increased number of residues that were involved in ion pairs or networks of ion pairs. Therefore, the mutants W200R and D58S were designed using site-directed mutagenesis to investigate F1 protease stability. The effects of addition and disruption of ion pair networks on the activity and various stabilities of mutant F1 proteases were compared with those of the wild-type F1 protease.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.5
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• pp.751-760
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• 2021

This study investigated the changes in water quality parameters and microbial colonies when ozone was applied to a semi-recirculating aquaculture system (semi-RAS) for the olive flounder Paralichthys olivaceus (500 g in average weight). Concentrations of ozone-produced oxidants (OPO) in rearing tanks were maintained at 0, 0.014, 0.025 mg/L as Cl₂ for 26 days. Except total ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, phosphate phosphorus, chemical oxygen demand, and total suspended solids decreased significantly with increasing OPO concentration in daily and weekly monitoring (P<0.05). Colony forming unit (CFU) counts of heterotrophic marine bacteria decreased in an OPO concentration-dependent manner. Overall reduction rates of microbial colonies in the treatments were 80% higher than those of the control (P<0.05). During the experiment, the OPO concentration-driven ozonation was reliably practiced without any adverse effects on the animals cultured in semi-RAS. Considering the biohazard, operating cost, and stability of ozonation, an OPO concentration of 0.014 mg/L would be sufficient to control water quality parameters and microbial colonies in a semi-RAS.

• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4527-4542
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• 2023

The present microbial reinforcement of rock and soil exhibits limitations, such as uneven reinforcement effectiveness and low calcium carbonate generation rate, resulting in limited solidification strength. This study introduces electroosmosis as a standard microbial grouting reinforcement technique and investigates its solidification effects on microbial-reinforced uranium tailings. The most effective electroosmosis effect on uranium tailings occurs under a potential gradient of 1.25 V/cm. The findings indicate that a weak electric field can effectively promote microbial growth and biological activity and accelerate bacterial metabolism. The largest calcium carbonate production occurred under the gradient of 0.5 V/cm, featuring a good crystal combination and the best cementation effect. Staged electroosmosis and electrode conversion efficiently drive the migration of anions and cations. Under electroosmosis, the cohesion of uranium tailings reinforced by microorganisms increased by 37.3% and 64.8% compared to those reinforced by common microorganisms and undisturbed uranium tailings, respectively. The internal friction angle is also improved, significantly enhancing the uniformity of reinforcement and a denser and stronger microscopic structure. This research demonstrates that MICP technology enhances the solidification effects and uniformity of uranium tailings, providing a novel approach to maintaining the safety and stability of uranium tailings dams.

• The Korea Journal of Herbology
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• v.25 no.4
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• pp.145-149
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• 2010

Objectives : Since cosmetics have been one of the help of life, unlike medicine, natural products have been used for cosmetics, generally giving the image of safety and relief compared to synthetic products. Among them, Houttuynia cordata has been known as a useful herbal medicine with antibiotic, anti-inflammatory and anti-oxidative activities. In this study, we were to use Houttuynia cordata extract on formulation of cosmetic emulsions. Methods : The effects of Houttuynia cordata extract on emulsion stability and viscoelastic properties of emulsion were measured using turbiscan and rheometer. And we assessed the anti-oxidative and antibiotic activities of Houttuynia cordata extract. Results : 1. The results of this investigation for emulsion stability showed that the stability emulsion containing Houttuynia cordata extract was decreased depending on concentration of Houttuynia cordata extract. 2. Super oxide dismutase activity was strongly dependents on concentration of Houttuynia cordata extract. 3. Houttuynia cordata extract showed good anti-microbial activity against Staphylococcus aureus. Conclusions : Houttuynia cordata extract can be effectively used in cosmetic emulsions when the relation between natural product extracts and formulation of cosmetics is elucidated.