• Journal of the Korean Society of Food Science and Nutrition
• /
• v.38 no.6
• /
• pp.787-794
• /
• 2009

In this study, a new method for extending storage-life and palatability of Betula platyphylla sap by applying lactic acid bacteria fermentation was developed. The fluids of saps were filtered through 0.22 ${\mu}m$ membrane filter and each fermented by 8 different lactic acid bacteria which are Lactobacillus acidophilus, Lactobacillus brevis, Leuconostoc mesenteroides, Leuconostoc lactis, Lactococcus lactis, Pediocossus pentosaceus, Pediococcus dextrinicus, Streptococcus thermophilus. All the tested lactic acid bacteria except P. dextrinicus grew fast up to $10^6{\sim}10^7cfu/mL$ levels and lowered pH down to about pH 4 levels in 48 hours in both saps. The produced organic acids and lowered pH level inhibited the growth of spoilage microorganisms almost completely for 2 weeks during storage at room temperature. Addition of xylitol in the saps before fermentation accelerated the growth of lactic acid bacteria and increased the sweetness and overall taste of final product. The filtration process did not affect the mineral compositions of Betula platyphylla saps. Also the compositions and amounts of minerals showed very minor differences before and after fermentation in Betula platyphylla saps inoculated with L. acidophilus. By applying lactic acid fermentation to extend storage-life of tree saps instead of heat treatment, it was possible to keep natural minerals in active forms without any modifications.

• Food Science of Animal Resources
• /
• v.26 no.3
• /
• pp.402-409
• /
• 2006

Although microorganisms are, in fact, the most diverse and abundant type of organism on Earth, the ecological functions of microbial populations remains poorly understood. A variety of bacteria including marine Vibrios encounter numerous ecological challenges, such as UV light, predation, competition, and seasonal variations in seawater including pH, salinity, nutrient levels, temperature and so forth. In order to survive and proliferate under variable conditions, they have to develop elaborate means of communication to meet the challenges to which they are exposed. In bacteria, a range of biological functions have recently been found to be regulated by a population density-dependent cell-cell signaling mechanism known as quorum-sensing (QS). In other words, bacterial cells sense population density by monitoring the presence of self-produced extracellular autoinducers (AI). N-acylhomoserine lactone (AHL)-dependent quorum-sensing was first discovered in two luminescent marine bacteria, Vibrio fischeri and Vibrio harveyi. The LuxI/R system of V. fischeriis the paradigm of Gram-negative quorum-sensing systems. At high population density, the accumulated signalstrigger the expression of target genes and thereby initiate a new set of biological activities. Several QS systems have been identified so far. Among them, an AHL-dependent QS system has been found to control biofilm formation in several bacterial species, including Pseudomonas aeruginosa, Aeromonas hydrophila, Burkholderia cepacia, and Serratia liquefaciens. Bacterial biofilm is a structured community of bacterial cells enclosed in a self-produced polymeric matrix that adheres to an inert or living surface. Extracellular signal molecules have been implicated in biofilm formation. Agrobacterium tumefaciens strain NT1(traR, tra::lacZ749) and Chromobacterium violaceum strain CV026 are used as biosensors to detect AHL signals. Quorum sensing in lactic acid bacteria involves peptides that are directly sensed by membrane-located histidine kinases, after which the signal is transmitted to an intracellular regulator. In the nisin autoregulation process in Lactococcus lactis, the NisK protein acts as the sensor for nisin, and NisR protein as the response regulator activatingthe transcription of target genes. For control over growth and survival in bacterial communities, various strategies need to be developed by which receptors of the signal molecules are interfered with or the synthesis and release of the molecules is controlled. However, much is still unknown about the metabolic processes involved in such signal transduction and whether or not various foods and food ingredients may affect communication between spoilage or pathogenic bacteria. In five to ten years, we will be able to discover new signal molecules, some of which may have applications in food preservation to inhibit the growth of pathogens on foods.

• Preventive Nutrition and Food Science
• /
• v.7 no.3
• /
• pp.305-309
• /
• 2002

Raw soybean sprouts were tested for contamination with the following bacteria which have potential for pathogenesis or food spoilage : Salmonella spp., Escherichia coli O157:H7, Yersinia enterocolitica, Vibrio parahae-molyticus, Aeromonas hydrophila, Plesidomonas shigeloides, Pseudomonas aeruginosa, Staphylococcus aureus, Lis-teria monocytogenes, Bacillus cereus, Clostridium perfringens, Campylobacter jejuni, Erwinia spp., and Fusarium spp. Three of the above strains were isolated from the sprouts, and identified by morphological and biochemical methods including an API kit and ATB automated identification system. The isolate cultured in Cereus selective agar, a selective medium, was a Gram-positive, rod shaped, anaerobic spore former. The biochemical and culture tests revealed the following characteristics: catalase-positive, no growth on Simmon's citrate, NO₂ production and requirement of arginine for growth; the ATB automated identification system gave 99.8 % agreement for the identification of Bacillus cereus to the species level. The isolate cultured in Macconkey agar selective medium was Gram-negative, rod shaped and a gas former; the ATB-system gave 99.9% agreement for the identification of Aeromonas hydrophila to the species level. The isolate found in Pseudomonas isolation agar was Gram-negative, rod shaped, cytochrome oxidase-positive, a reducer of nitrates to nitrogen, and pyocyanin producer; the ATB-system gave 99.9 % agreement for the identification of Pseudomonas aeruginosa to the species level. These results indicate that the three bacteria species present in the soybean sprouts were Bacillus cereus, Aero-monas hydrophila, and Pseudomonas aeruginosa. Salmonella spp., Escherichia coli O157:H7, and Yersinia enter-ocolitica, which are associated with serious disease in humans, were not isolated from soybean sprouts examined in this study.

• Food Science and Preservation
• /
• v.6 no.2
• /
• pp.239-244
• /
• 1999

Antimicrobial activity to the extracts of Perilla frutescens Briton var. acuta Kudo was investigated against various foodborne pathogenes or food poisioning microorganisms(Aspergillus flavus KCTC 6143 and KCTC 6961, Aspergillus niger ATCC 4695, Listeria monocytogenes ATCC 15313, Staphylococcus aureus 196E ATCC 13565, Escherichia coli O157:H7 ATCC 43895, Salmonella typhimurium ATCC 13311 and Yersinia enterocolitica). The ethanol extract of Perilla frutescens Briton var. acuta Kudo was very stable over heat at $121^{\circ}C$ for 15 min. In concentration of $1000\mu\textrm{g}$/mL into culture broth(TSB), the ethanol extract of Perilla frutescens Briton var. acuta Kudo showed the strongest antimicrobial activities against Listeria monocytogenes, followed by Staphylococcus aureus 196E, Salmonella typhimurium. Gram negative bacteria(Escherichia coli O157:H7, Salmonella 쇼phimurium, Yersinia enterocolitica) were less sensitive than Cram positive bacteria but the growth of Escherichia coli O157:H7 and Yersinia exterocolitica were inhibited with increasing concentrations of the extract in culture broth.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.33 no.3
• /
• pp.494-499
• /
• 2004

This study was investigated the antimicrobial activity of clove extracts according to extraction solvents. The extracts were tested for their antimicrobial activity against several food spoilage microorganisms including Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Salmonella typhimurium and Pseudomonas aeruginosa. The methanol extract showed stronger antimicrobial activities than water extract. However, petroleum ether extract did not show antimicrobial activity. The water extract of clove showed growth inhibition effect against Escherichia coli, Salmonella typhimurium and Staphylococcus aureus, whereas no effect against Bacillus subtilis. The methanol extract of clove extracts showed more sensitive antimicrobial activity in Gram (+) bacteria than in Gram (-) bacteria. The antimicrobial activities were increased with increasing concentration of the clove extract.

• Food Science of Animal Resources
• /
• v.38 no.2
• /
• pp.251-258
• /
• 2018

We investigated microbial and quality changes in wrap-packaged dry-aged beef after completion of aging and subsequent storage in a refrigerator. After 28 days of dry aging (temperature, $4^{\circ}C$; RH, approximately 75%; air flow velocity, 2.5 m/s), sirloins were trimmed, wrap-packaged, and stored at $4^{\circ}C$ for 7 days. Analyses of microbial growth, pH, volatile basic nitrogen (VBN), 2-thiobarbituric acid-reactive substance (TABRS), and instrumental color, myoglobin, and sensory evaluation were conducted on days 0, 3, 5, and 7. The results show that the number of total aerobic bacteria (TAB), yeast, and lactic acid bacteria increased with an increase in storage days, whereas no change in the growth of mold was observed during 7 days of storage. Based on the legal standard for TAB count, the estimated shelf-life of wrap-packaged dry-aged beef was predicted to be less than 12.2 days. However, the shelflife should be less than 6.3 days, considering the result of sensory quality (odor, taste, and overall acceptance). No significant change in visible appearance was also observed during 7 days of storage. The results suggest that the present quality indicators for meat spoilage (pH, VBN, and TBARS) should be re-considered for dry-aged beef, as its characteristics are different from those of fresh and/or wet-aged beef.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.48 no.2
• /
• pp.244-248
• /
• 2015

We explored the efficiency of natural antibacterial agents used to enhance the self-life and sensory properties of shucked and packed Pacific oyster Crassostrea gigas, which are in high demanded. First, we screened natural resources exhibiting antibacterial activity against food spoilage and pathogenic bacteria. Of theses, ignited oyster shell powder (IOS) and the natural food preservative, lactic acid bacteria fermented powder (LBF), were selected for further study considering the efficacy, mass production, and cost. The addition of 0.1% IOS (W/V) and 0.5% LBF (W/V) to shucked and packed oyster optimally extended the shelf-life without affecting the sensory evaluation. The results obtained in this study will provide a clue to enhance self-life in raw oyster products.

• Advances in materials Research
• /
• v.9 no.3
• /
• pp.233-250
• /
• 2020

In this study, a chitosan based coating method was developed and applied on the shoe lining leather surface for evaluating its inhibition to bacterial and fungal attacks. At first, chitosan was prepared from raw prawn shells and then the prepared chitosan solution was applied onto the leather surface. Secondly, the characterization of the prepared chitosan and chitosan treated leather was performed by solubility test, ATR-FTIR, XRD pattern, SEM and TGA. Evaluation of antimicrobial efficacy of chitosan was assessed against two gram positive, two gram negative bacteria and a reputed fungi by agar diffusion test. The results of this study demonstrated that chitosan took place in both the surface of collagen fibres and inside the collagen matrix of crust leather. The chitosan showed strong antimicrobial activities against all the tested microorganisms and the inhibition increased with increasing percentage of chitosan. Therefore, the prepared chitosan in this study can be an environment friendly biocide, which functions simultaneously against different spoilage bacteria and fungi on the finished leather surface. Thus by using the prepared chitosan in shoe lining leather, the possibility of microbial attack during shoe wearing can be minimized which is one of the important hygienic requirements of footwear.

• Asian-Australasian Journal of Animal Sciences
• /
• v.26 no.9
• /
• pp.1304-1312
• /
• 2013

The effects of storage period and aerobic deterioration on the bacterial community were examined in Italian ryegrass (IR), guinea grass (GG), and whole-crop maize (WM) silages. Direct-cut forages were stored in a laboratory silo for 3, 7, 14, 28, 56, and 120 d without any additives; live counts, content of fermentation products, and characteristics of the bacterial community were determined. 2,3-Butanediol, acetic acid, and lactic acid were the dominant fermentation products in the IR, GG, and WM silages, respectively. The acetic acid content increased as a result of prolonged ensiling, regardless of the type of silage crop, and the changes were distinctively visible from the beginning of GG ensiling. Pantoea agglomerans, Rahnella aquatilis, and Enterobacter sp. were the major bacteria in the IR silage, indicating that alcoholic fermentation may be due to the activity of enterobacteria. Staphylococcus sciuri and Bacillus pumilus were detected when IR silage was spoiled, whereas between aerobically stable and unstable silages, no differences were seen in the bacterial community at silo opening. Lactococcus lactis was a representative bacterium, although acetic acid was the major fermentation product in the GG silage. Lactobacillus plantarum, Lactobacillus brevis, and Morganella morganii were suggested to be associated with the increase in acetic acid due to prolonged storage. Enterobacter cloacae appeared when the GG silage was spoiled. In the WM silage, no distinctive changes due to prolonged ensiling were seen in the bacterial community. Throughout the ensiling, Weissella paramesenteroides, Weissella confusa, and Klebsiella pneumoniae were present in addition to L. plantarum, L. brevis, and L. lactis. Upon deterioration, Acetobacter pasteurianus, Klebsiella variicola, Enterobacter hormaechei, and Bacillus gibsonii were detected. These results demonstrate the diverse bacterial community that evolves during ensiling and aerobic spoilage of IR, GG, and WM silages.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.32 no.3
• /
• pp.413-417
• /
• 2003

To evaluate the antimicrobial activity of green tea against putrefactive microorganism in steamed bread, antibacterial activity of green tea extract against well-known strains of spoilage bacteria (Bacillus subtilis ATCC 6633, Bacillus pulmilus KCTC 3348 and Bacillus cereus IFO 12113) and mold (Aspergillus niger KCCM l1239) in bread was determined using the paper disk method. The green tea extract (GTE) showed the inhibition effects on the growth of all the strains of bacteria and mold at 1, 2, 3% levels. The activity of GTE was stable in the wide range of pH (4~9) and temperature (50~20$0^{\circ}C$). When green tea powder (GTP: 1, 3, 5%) was added to steamed bread increase of total bacterial and mold counts declined during storage at 25"C as the levels of GTP increased. By addition of 5% GTP, mold appeared 1 day late extending shelf life of steamed bread compared to control bread without GTP. Therefore, the levels of GTP added to steamed bread could be more than 5% for extended shelf life and wholesomeness of steamed bread.read.