• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.6
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• pp.810-817
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• 2023

Oysters are a highly consumed seafood throughout Korea, but they have a short shelf life because they support rapid microbial growth due to their of high moisture content and fragile muscle tissue. We examined natural food additives including lactic acid bacteria fermentation powder, rosemary extract, and lemon juice for their ability to preserve raw oyster Crassostrea gigas quality. Samples were stored at 4℃, and microbiological and physicochemical analyses were conducted. Among the natural additives tested, lemon juice was the most effective. Lemon juice was thus applied at different concentrations (50-300 ppm) to quantitatively assess its effect on total viable cell count, pH, glycogen, soluble protein, and turbidity. 200 ppm was confirmed to be optimal, and is projected to extend shelf life by 2 days compared to the control group.

• Korean Journal of Food Science and Technology
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• v.45 no.2
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• pp.191-198
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• 2013

The storage quality of fresh Sulhyang strawberries packaged under modified atmospheres was investigated to examine the effect of high $O_2$ on the fruit. Fresh strawberries were packed into PP trays and top-sealed with PET/PP film. Initial gas compositions inside the packages were varied with air, 40% $O_2$/60% $N_2$, 60% $O_2$/40% $N_2$, and 80% $O_2$/20% $N_2$. Sealed packages in PE film bags with air and perforated PP trays were also used as another treatment and control, respectively. Quality attributes and viable cell counts of pathogenic bacteria were assessed during storage at $5^{\circ}C$ for 12 days. High $O_2$ concentration showed no significant effects on the physicochemical and microbial qualities of strawberries. Fruit packaged in PE film bags with 6-15% $O_2$ and 7-9% $CO_2$ during storage had the lowest viable cell counts of inherent microorganisms among the treatment samples. Growth of pathogenic bacteria was suppressed in perforated packages where molds occurred frequently. In an overall sensory aspect, the PE film packages exhibited higher scores than the others at the end of storage period. The experimental results suggested that gas-permeable film packaging with an appropriate combination of $O_2$ and $CO_2$ rather than gas-barrier tray packaging with an initially high $O_2$ concentration would be suitable for improving the storability of strawberries.

• Applied Biological Chemistry
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• v.40 no.2
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• pp.89-94
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• 1997

In order to reduce energy input in direct ethanol production from raw starch by co-immobilized Aspergillus awamori(A) and Zymomonas mobilis(Z), A-Z 36 culture system which was changed to anaerobic after 36 h of aerobic fermentation without sterilization was investigated. This immobilized cell system can not be carried out under unsterile conditions because of growth of microbial contaminants from original medium. Among some food additives such as sorbic acid, benzoic acid, dehydroacetic acid, p-hydroxybenzoic acid, Vantocil IB and Neupectin-L, Vantocil IB and Neupectin-L were a potent antibacterial agent in A-Z 36 culture cell system and were not affected in hydrolysis of substrate as compared with the case of control. Ethanol yield(6.9 g/l) in system of addition of 0.1% Neupectin-L was slightly higher than that in control(6.4 g/l). When 2% starch was fed five times in fed-batch culture with 0.1% Neupectin-L, ethanol yield and productivity were 34 g/l and 2.0 g/l/day, respectively.

• Ecology and Resilient Infrastructure
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• v.1 no.1
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• pp.19-24
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• 2014

The research evaluates the possibility of generating electricity using pyrite containing mine tailings, which are the major cause of acid mine drainage (AMD), by applying iron oxidizing bacteria (in this case, Acidithiobacillus ferrooxidans) and chemical fuel cell technology. The changes in the aqueous $Fe^{2+}$ concentration, which can represent an ionized form of pyrite, with an initial concentration of 9,000 mg/L were investigated during the 20 d growth period. Both the $Fe^{2+}$ and total iron (i.e., total $Fe^{2+}$)concentrations with or without A. ferrooxidans were observed. The $Fe^{2+}$ concentration decreased to about 6,000 mg/L, in the abiotic condition, while it decreased to about 400 mg/L in the biotic condition. The results showed that the increased $Fe^{2+}$ oxidation in the presence of A. ferrooxidans (i.e., catalytic ability of A. ferrooxidans) can be applied to electricity generation using pyrite containing mine tailings. In the co-presence of A. ferrooxidans and pyrite containing mine tailings, $Fe^{2+}$ oxidation and hence electron production increases, which, in turn, improves current density. This study can be applied to utilize ecological functions of indigenous bacteria in mine areas to enhance electricity generation efficiency.

• Journal of Animal Science and Technology
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• v.46 no.5
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• pp.871-878
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• 2004

Pulsed electric fields(PEF) technology is one of the latest nonthermal methods of food processing for obtaining safe and minimally processed foods. This technology can be effectively explored for obtaining safe food with minimum effect on nutritional, flavor, rheological and sensory qualities of food products. The process involves the application of high voltage(typically 20 ${\sim}$ 80 kv/cm) to foods placed between two electrodes. The mode of inactivation of microorganism; by PEP processing has been postulated in term; of electric breakdown and electroporation. The extent of destruction of microorganisms in PEF processing depends mainly on the electric field strength of the pulses and treatment time. For each cell types, a specific critical electric field strength and specific critical treatment time are required depending on the cell characteristics and the type and strength of the medium where they have been present. The effect also depends on the types of microorganisms and their phase of growth. A careful combination of processing parameters has to be selected for effective processing. The potential applications of PEF technology are numerous ranging from biotechnology to food preservation. With respect to food processing, it has already been established that, the technology is non-thermal in nature, economical and energy efficient, besides providing minimally processed foods. This article gives a brief overview of this technology for food processing applications.

• Journal of the Korea Convergence Society
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• v.13 no.1
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• pp.149-160
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• 2022

In this study, the physical quality and microbial changes of ginseng sprout according to the pretreatment process and packaging container were evaluated to improve the storage properties of ginseng sprout produced in smart farm. Quality change during storage (10 days) according to pretreatment method (ascorbic acid, citric acid, peroxyacetic acid) and packaging container (expanded polystyrene (EP), polypropylene (PP), polyethylene (PE), polypropylene + polyethylene + cast polypropylene (PP+PE+CPP)) was evaluated in terms of texture, viable cell count, water content, and color. As a result of comparison according to the type of pretreatment, the citric acid treatment group showed the lowest texture change and the effect on inhibition of bacterial growth. On the other hand, citric acid, which was most effective among pretreatments, was treated in all samples and then stored in 4 types of containers. Specially, the ginseng sprout in PP packaging container was not observed significant softening or color changes after 10 days storage, and the lowest changes in viable cell number. Therefore, this study was shown that citric acid treatment and use of PP packaging container are effective in increasing the shelf life of ginseng sprout.

• Korean Journal of Microbiology
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• v.47 no.3
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• pp.218-224
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• 2011

Lactic acid bacteria (LAB) OA18 was isolated from yogurt prepared by using Kefir Grain as a starter. The OA18 strain was a Gram-positive, cocci-type bacterium, and able to grow anaerobically with $CO_2$ production. The OA18 strain grew well on MRS broth supplemented with 50 mM arginine at $30-37^{\circ}C$ and pH of 7.0-9.0. The optimum temperature and pH for growth are $37^{\circ}C$ and pH 7.0. The isolate fermented ribose, D-glucose, cellobiose, D-trehalose, but not L-xylose, D-melibiose, and inositol. The 16S rRNA gene sequence of the isolate showed 99.8% homology with the Enterococcus faecalis 16S rRNA gene (Access no. AB012212). Based on the biochemical characteristics and 16S rRNA gene sequence analysis data, it was identified and named as E. faecalis OA18. The E. faecalis OA18 strain showed a high ornithine-producing capacity in the presence of arginine and also showed an antimicrobial activity against Streptomyces strains such as Streptomyces coelicolor subsp. Flavus, S. coeruleorubidus, S. coeruleoaurantiacus, S. coelicolor, S. coeruleoprunus. The cell growth of E. faecalis OA18 strain was maintained in MRS broth with a NaCl concentration of 0-7%.

• Journal of Life Science
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• v.17 no.12
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• pp.1709-1716
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• 2007

The health benefits of garlic (Allium sativum L.) are derived from a wide variety of components and from the different ways it is administered. The known health benefits of garlic include cardiovascular protective effects, stimulation of immune function, reduction of blood glucose level, protection against microbial, viral and fungal infections, as well as anticancer effects. In the present study, it was examined the effects of water extract of A. sativum (WEAS) on the growth of cultured human tumor cells in order to investigate its anti-proliferative mechanism. Treatment of WEAS to tumor cells resulted in the growth inhibition, especially in leukemia cells, which was associated with induction of G2/M arrest of the cell cycle and apoptosis. In order to further explore the critical events leading to apoptosis in WEAS-treated U937 human leukemia cells, the following effects of WEAS on components of the mitochondrial apoptotic pathway were examined: generation of reactive oxygen species (ROS), alteration of the mitochondrial membrane potential (MMP), and the expression changes of Bcl-2 and IAP family proteins. The cytotoxic effect of WEAS was mediated by its induction of apoptosis as characterized by the occurrence of DNA ladders, apoptotic bodies and chromosome condensation in U937 cells. The WEAS-induced apoptosis in U937 cells was correlated with the generation of intracellular ROS, collapse of MMP, activation of caspase-3 and down-regulation of anti-apoptotic proteins. The quenching of ROS generation with antioxidant N-acetyl-L-cysteine conferred significant protection against WEAS-elicited ROS generation, caspase-3 activation, G2/M arrest and apoptosis. In conclusion, the present study reveals that the cellular ROS generation plays a pivotal role in the initiation of WEAS-triggered apoptotic death in U937 cells.

• Korean journal of food and cookery science
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• v.23 no.6
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• pp.848-857
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• 2007

Sikhe, a traditional Korean drink, was prepared with Hovenia dulcis extract (HDE), and its quality and storage characteristics were evaluated through sensory and microbial analyses. In the color analysis, the lightness of the Sikhe showed a decreasing tendency according to the addition of HDE, while redness and yellowness increased. The Sikhe prepared with 20% HDE had the highest sugar concentration at 12days of storage ($4^{\circ}C$). Interms of sensory quality, both the 20% and 40% HDE-added Sikhes had the highest overall preference. The microbial cell counts presented no distinct differences early in the storage. period, but the general bacteria counts of the Sikhe made with the increasing concentrations of extracts decreased with a longer storage period. The coliform counts of the Sikhe prepared without HDE (control) was 10.5 CFU/g at 10 days of storage, but the 100% HDE-added Sikhe had a level of 7.9 CFU/g at 16 days of storage. These results indicates that Hovenia dulcis may inhibit normal microbial growth and extend the shelf-life on Sikhe.

• Applied Biological Chemistry
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• v.23 no.1
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• pp.64-72
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• 1980

Industrial wastes from pulp and food plants were treated with microorganisms to clarify organic waste-water and to produce cells as animal feed, and results were summarized as follows. (1) Waste-water from pulp, beer, bread yeast, and ethanol distillation plants contained $1.4{\sim}1.5%$ of total sugar, $0.25{\sim}0.35%$ nitrogen, and biological oxygen demand (BOD) was $400{\sim}25,000$, chemical oxygen demand (COD), $500{\sim}28,000$, and pH, $3.8{\sim}7.0$. The BOD and COD were highest in waste-water from ethanol distillation plants among others. (2) Bacterial and yeast counts were $4{\times}10^4-1{\times}10^9,\;2{\times}10^2-7{\times}10^4/ml$ in waste-water. (3) Bacteria grew better in pulp waste and yeasts in beer, bread yeast, and ethanol distillation waste. (4) Saccharomyces cerevisiae SAFM 1008 and Candida curvata SAFM 70 were the most suitable microorganisms for clarification of ethanol distillation waste. (5) When liquid and solid waste from ethanol distillation were treated with microbial cellulase, xylanase, and pectinase, solid waste was reduced by 36%, soluble waste was increased, and recuding sugar content was increased by 1.3 times which provided better medium than untreated waste for cultivation of yeasts. (6) Optimum growth conditions of the two species of yeast in ethanol distillation waste were pH 5.0, $30^{\circ}C$, and addition of 0.2% of urea, 0.1% of $KH_2PO_4$ and 0.02% of $MgSO_4$. (7) Minimum number of yeast for proper propagation was $1.8{\times}10^5/ml$. (8) C. curvata70 was better than cerevisae for the production of yeast cells from ethanol distillation waste treated with microbial enzymes. (9) S. cerevisiae produced 16 g of dried cell per 1,000ml of ethanol distillation waste and reduced BOD by 46%. C. curvata produced 17.6g of dried cell and reduced BOD by 52% at the same condition. (10) Yeast cells produced from the ethanol distillation waste contained 46-52% protein indicating suitability as a protein source for animal feed.