• Journal of Microbiology and Biotechnology
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• v.23 no.2
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• pp.167-176
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• 2013

A novel bioactive molecule produced by Bacillus thuringiensis subsp. kurstaki Bn1 (Bt-Bn1), isolated from a common pest of hazelnut, Balaninus nucum L. (Coleoptera: Curculionidae), was determined, purified, and characterized in this study. The Bt-Bn1 strain was investigated for antibacterial activity with an agar spot assay and well diffusion assay against B. cereus, B. weinhenstephenensis, L. monocytogenes, P. savastanoi, P. syringae, P. lemoignei, and many other B. thuringiensis strains. The production of bioactive molecule was determined at the early logarithmic phase in the growth cycle of strain Bt-Bn1 and its production continued until the beginning of the stationary phase. The mode of action of this molecule displayed bacteriocidal or bacteriolytic effect depending on the concentration. The bioactive molecule was purified 78-fold from the bacteria supernatant with ammonium sulfate precipitation, dialysis, ultrafiltration, gel filtration chromatography, and HPLC, respectively. The molecular mass of this molecule was estimated via SDS-PAGE and confirmed by the ESI-TOFMS as 3,139 Da. The bioactive molecule was also determined to be a heat-stable, pH-stable (range 6-8), and proteinase K sensitive antibacterial peptide, similar to bacteriocins. Based on all characteristics determined in this study, the purified bacteriocin was named as thuricin Bn1 because of the similarities to the previously identified thuricin-like bacteriocin produced by the various B. thuringiensis strains. Plasmid elution studies showed that gene responsible for the production of thuricin Bn1 is located on the chromosome of Bt-Bn1. Therefore, it is a novel bacteriocin and the first recorded one produced by an insect originated bacterium. It has potential usage for the control of many different pathogenic and spoilage bacteria in the food industry, agriculture, and various other areas.

• The Journal of Natural Sciences
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• v.7
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• pp.53-58
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• 1995

To elucidate the effect of egg white lysozyme from Ogol fowl on the preservation of milks, fishcurd and sausage, changes of pH, volatile base nitrogen content and viable cell count were investigated during the storage periods at $20^{\circ}C$, $30^{\circ}C$ and $37^{\circ}C$ after the addition of lysozyme in each foods. Volatile base nitrogen count of raw milk as marker of spoilage was lowest(63 mg%) in 0.05% lysozyme addition lot which was stored at $20^{\circ}C$ for 2 days, and its preservation effect by lysozyme at $30^{\circ}C$ was enhanced with addition of glycine(0.1%). Preservation effect by lysozyme in commercial milk at $37^{\circ}C$ and in fishcurd at $5^{\circ}C$ and $20^{\circ}C$ were also good, and when sausage was stored at $5^{\circ}C$ after treatment of lysozyme instead of sorbic acid, its preservation effect was acceptable.

• Journal of the Korean Home Economics Association
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• v.38 no.12
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• pp.241-248
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• 2000

포도는 전세계에서 널리 소비되는 과실로 포도 과피에 존재하는 천연색소인 flavonoid는 혈중 콜레스테롤 함량 저하, 항알러지성, 항암성, 항바이러스성, 항염성의 생리적 기능이 있다고 알려져 있다. 최근에 들어와 이들 과실주스 가공에 열처리를 최소화하는 살균방법으로 자연 그대로의 영양성분, 맛과 향기 개선을 위한 초고압 처리에 관한 연구가 폭넓게 이루어지고 있다. 본 연구는 주스에서 문제가 되고 있는 ethanolic spoilage 균주인 S. cerevisiae의 초고압 살균 효과와 세포 구조적 형태를 연구하였다. 1.2$\times$$10^{6}$ cfu/ml의 S. cerevisiae를 포도주스에 접종하고 24시간 배양하여 멸균한 high barrier주머니에 20m1씩 넣고 2$0^{\circ}C$ 에서 200-600 MPa 조건으로 0-20분 동안 초고압 장치로 실시하였다. 생균수는 YM agar로 poured 방법으로 실시하였으며 200 MPa에서 5, 10, 15, 20분 후의 생균수는 각각 2.2$\times$$10^{7}$ , 4.5$\times$$10^4$, 2.8$\times$$10^4$, 9.8$\times$$10^3$, 9.5$\times$$10^3$cfu/ml로 tailing 현상을 관찰하였고, 400 MPa에서 5분 후 급격하게 감소하였다. S. cerevisiae의 사멸속도는 초고압 처리가 높을수록 증가했으며 세포 손상도는 압력과 처리시간이 길수록 증가하였다. 이들 조건에 따른 효모 세포의 구조적 관찰을 scanning electron microscopy와 electron microscopy로 하였다. S. cerevisiae 세포는 압력에 의한 pinhole, surface roughening을 발견하였고, 세포 내부의 세포질, 액포, 핵 손상과 세포질 물질들이 압력에 의하여 세포벽으로 이동하여 내부가 비어있는 현상을 관찰하였다.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 1993.12a
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• pp.6-9
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• 1993

According to changes in population, economic conditions, life-stile and eating habits, the frui ts and vegetables market wi 11 be shi fted from processed (i. e. , canned) to fresh. Undressed fresh produce, consisting of washed, disinfected and peeled fruits and vegetables that either sliced or grated, are currently increased in demand by retail and institutional market which use them as salad components or in ready-to use foods, Main attributes of minimally processed fruits and vegetables are convenience and fresh-like quality. Minimally processed Products readily deteriorate in quality, especially color and texture, as a result of endogeneous enzyme enhanced respiration and microorganisms which lead to reduced shelf Iife. According to changes in population, economic conditions, life-stile and eating habits, the frui ts and vegetables market wi 11 be shi fted from processed (i. e. , canned) to fresh. Undressed fresh produce, consisting of washed, disinfected and peeled fruits and vegetables that either sliced or grated, are currently increased in demand by retail and institutional market which use them as salad components or in ready-to use foods, Main attributes of minimally processed fruits and vegetables are convenience and fresh-like quality. Minimally processed Products readily deteriorate in quality, especially color and texture, as a result of endogeneous enzyme enhanced respiration and microorganisms which lead to reduced shelf Iife. Thus. to prevent these undesirable changes , val'ious techniques such as controlled atmosphere (CA) storage, modified atmosphere OIA) storage, including vacuum packaging have been receiving considerable attention, Although milch research has been done to find optimal conditions for whole intact frui ts and vegetables, only limi ted information is avai lable on fresh cut. and other minimally processed products. 81 iced frui ts exhibi t increas~d ethylene production and respiration compal'ed to whole f, 'uits during distribution in response to tissue damage. As a result, accelerated senescence and enzymatic browning OCCUI', Recent l'esearch on minimally processed fl'uits and vegetables has mainly focused on methods to inhibit browning, due to ban on use of sulfur dioxide, In order to retard or prevent these physiological changes, val'ious al ternatives, reducing agents. acidulants, chelating agents and inol'ganic sal ts have been evaluated for use on fresh cut fl'ui ts. Al though some agents were effective replacement for sulfur dioxide. consum$\textregistered$I'S demandless use of chemical on such products. Shel~ life of minimally processed products has been extended by inhibition of metabolic reactions associated with loss of quality and by inhibition of aerobic spoilage caused by wide variety of microorganisms. Appl ication of ~I.-\ packaging, including vacuum packaging, retards the rate of respiration, prevents growth of aerobic spoilage organisms, inhibits oxidation and color deterioration. Tissue softening is another major problem in minimally processed products because enzymes re 1 a ted to ce 11 wa 11 degrada t i on are not inactivated. Various treatments have been investigated for retardation of the softening of sliced products. Some studies have concentrated on the application of an active packaging system with ~I, l. packaging and calcium infi 1 tration as possible measures to retain firmness of processed products. In my opinion, one important step for production of minimally processed frui ts wi th favorabl e color of cut surface and firm texture is the selection of better cultivar. As the view, changing tendency of fresh color by apple cultivars and relationship between the tendency and PPO activity will be discussed in the seminar. In addition to the topic, research result on quality enhancement of fresh apple slices by heat shock treatment will be introduced.

• Food Science and Preservation
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• v.19 no.2
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• pp.167-172
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• 2012

The antimicrobial activities of $Smilax$ $china$ L. against spoilage bacteria isolated from $Mang-gae$ rice cake were investigated and the storage stability of the $Mang-gae$ rice cake was enhanced. Spoilage bacteria, which cause $Mang-gae$ rice cake to rot, were isolated from commercial $Mang-gae$ rice cake, and most of the isolated strains were identified as $Bacillus$ sp. After the leaves, roots, shoots, and stalks of the $Smilax$ $china$ L. were extracted using 50% ethanol as the solvent, their antimicrobial activities were investigated using the paper disc method by treating them with 50 ${\mu}L$ of $Bacillus$ $cereus$, which is known as a major pathogenic micro-organism in foods that contain starch, as the test organism. The antimicrobial activities of the extracts were compared according to the size of the clear zones around the paper discs. The root extract showed significant antimicrobial activities. When red beans, which are used as stuffing for $Mang-gae$ rice cake, were treated with the root extract of the $Smilax$ $china$ L., the viable cell count of the $Mang-gae$ rice cake was 5.04 Log CFU/g after 48-hr storage, and the cake showed significantly slower growth of bacteria than with commercial products. These results show that treatment of red beans with $Smilax$ $china$ root extract could improve the storage stability of $Mang-gae$ rice cake.

• Korean Journal of Food Science and Technology
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• v.11 no.4
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• pp.217-223
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• 1979

The present study was to investigate the effect of sugars on the psychrophillic spoilage in ground meat. The obtained results were summarized as follows: 1. The minimum pH values for the ground beef containing 2, 5 and 10 % glucose were 5.25, 5.15 and 4.5, respectively. For the ground pork, the respective values were 5.1, 4.45 and 4.1. 2. Total aerobes, coliform, lactic acid bacteria and lactobacillus counts per gram for the control and 2% glucose-contained ground beef after 9 days for storage at $5^{\circ}C$ were $8.3{\times}10^9vs\;6.0{\times}10^7,\;3.5{\times}10^5vs\;2.4{\times}10^3,\;5.8{\times}10^7vs\;4.7{\times}10^6$ and $3.6{\times}10^5vs\;4.2{\times}10^6$ respectively. For the ground pork, the respective values were $1.2{\times}10^{10}vs\;7.8{\times}10^8,\;3.4{\times}10^5vs\;3.1{\times}10^4,\;5.5{\times}10^7vs\;4.5{\times}10^6$ and $3.3{\times}10^5vs\;3.7{\times}10^5$. The glucose-added ground meat showed higher counts than those of the controls only in the case of lactobacillus without any apparent adverse effects. 3. The length of storage time until the depletion of added glucose was 12, 16 and 28 days for the 2, 5 and 10 % glucose contained ground beef and 9, 16 and 30 days for the ground pork, respectively. pH did not start to increase until the added glucose was depleted completely. 4. The addition of glucose extended significantly the average shelf-life of ground beef at refrigeration condition $(5^{\circ}C)$. The extended shelf-life over the control was 7, 9 and 12days for the 2, 5 and 10 % glucose contained ground beef and 8, 10 and 12 days for the respective ground porks. 5. Although the addition of disaccharides (maltose, lactose, saccharose) lowered the pH of ground meat, the extension of shelf-life as seen in glucose treatment was not affected. In fact, the higher the concentration of added disaccharides was, the greater the degree of putrefaction occurred.

• Korean Journal of Food Science and Technology
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• v.30 no.4
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• pp.957-963
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• 1998

Several medicinal herbs, which are nontoxic and have been used widely in traditional folk medicine, were extracted and antimicrobial activity of the extracts was investigated against various foodborne pathogens or food poisioning microorganisms. The ethanol extract of Sansa, Hwangryun, Cheukbaek, and Seokchangpo showed strong antimicrobial activities against Gram postive and Gram negative bacteria, whereas those of Sakunja, Sukjihwang and Baekji had little antimicrobial activities on microorganisms tested. Among medicinal herb extracts, ethanol extract of Coptis chinensis Franch (hwangryun) showed the strongest antimicrobial activity. Antimicrobial activity of ethanol extract of Coptis chinensis Franch was not destroyed by heating at $100^{\circ}C$ for 60 min and at $121^{\circ}C$ for 30 min, which is very stable over heat. The pH effect on minimal inhibitory concentrations (MIC) of the extract of Coptis chinensis Franch indicated that MIC was reduced with increasing the pH value of the medium. The inhibitory effect of partially purified substance from the ethanol extract of Coptis chinensis Franch on the growth of Listeria monocytogenes and Staphylococcus aureus was investigated. Growth of those strains occurred at the concentration of $100{\;}{\mu}g/mL$ and were inhibited at $500{\;}{\mu}g/mL$, whereas those strains was completely inactivated in the presence of $1000{\;}{\mu}g/mL$.

• Journal of Life Science
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• v.30 no.3
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• pp.298-303
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• 2020

This study aimed to investigate possible applications of Rodgersia podophylla in the food and cosmetic industry. Ethanol extracts of leaves (RP-L), branches (RP-B), and root (RP-R) were prepared, and their antimicrobial, antioxidant, and anti-diabetic activities were evaluated. The polyphenol content in the RP-R, RP-L, and RP-B extracts was 79.6, 30.4, and 16.9 mg/g, respectively. An antimicrobial activity assay showed that the RP-L and RP-R extracts exhibited strong growth inhibition of pathogenic and food spoilage Gram-positive bacteria. Furthermore, the RP-R extract inhibited the growth of the Gramnegative E. coli and P. vulgaris bacteria. All extracts showed strong scavenging activity for DPPH, ABTS, nitrite, and reducing power determined by A 700 nm. In particular, the RC₅₀s of the RP-R extract for the DPPH anion and ABTS cation were 23.0-29.7 and 15.0-18.2 ㎍/ml, respectively, which are comparable to those of vitamin C (9.8 and 8.0 ㎍/ml, respectively). An activity assay of α-glucosidase and β-amylase suggested a high potential for the RP-R extract as an anti-diabetic agent. Its inhibition levels of α-glucosidase and β-amylase at 0.5 mg/ml were 6.9 and 48.5%, respectively. This is the first report of the antimicrobial and anti-diabetic activities of R. podophylla. Our results suggest that RP-L and RP-R extracts could be developed as novel cosmeceutical and functional food resources.

• Journal of Dairy Science and Biotechnology
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• v.33 no.1
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• pp.47-57
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• 2015

Sodium is an essential nutrient with very important functions, including regulation of the extracellular fluid volume and active transport of molecules across the cell membranes. Since high levels of dietary sodium are associated with a high prevalence of hypertension, prehypertension, and other adverse effects on health, many national and international health organizations (WHO, FAO, etc.) recommend that sodium intake should be significantly decreased. In developed nations, cheese products, from among many processed foods, can cause high salt intake. Hence, there is an urgent need to reduce the content of salt in cheese processing, using various substitutes of sodium chloride (NaCl). In general, salt (NaCl) has been used as a food preservative to limit and (or) kill the growth of foodborne pathogens and spoilage organisms by decreasing the water activity, and to improve texture and flavor. To maintain public health, the salt content in cheese should be decreased without influencing the physicochemical properties of cheese. Therefore, the objective of this review is to outline the upcoming technologies used to reduce the salt content in different types of cheese using various substitutes.

• Food Science of Animal Resources
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• v.38 no.1
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• pp.189-202
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• 2018

This study was conducted to evaluate the effects of fermenting temperature on the applicability of Lactobacillus plantarum for production of fermented sausages as starter cultures, and its applicable efficiency was also compared with those inoculated with commercial starter culture or non-inoculated control. The L. plantarum isolated from a naturally-fermented meat, identified by 16S rDNA sequencing and again identified by de novo Assembly Analysis method was used as a starter culture. Six treatments: 3 with L. plantarum at different fermenting temperatures (20, 25 and $30^{\circ}C$), and other 3 treatments (1 with commercial starter culture, 1 with its mixture with L. plantarum and 1 non-inoculated control) fermented under the same conditions ($25^{\circ}C$) were prepared. Results revealed that the fermenting temperature considerably affected the pH change in samples added with L. plantarum; the highest pH drop rate (1.57 unit) was obtained on the samples fermented at $30^{\circ}C$, followed by those at $25^{\circ}C$ (1.3 unit) and $20^{\circ}C$ (0.99 unit) after 4 days fermentation. Increasing the temperature up to $30^{\circ}C$ resulted in significantly lower spoilage bacteria count (5.15 log CFU/g) and lipid oxidation level in the products inoculated with L. plantarum. The sensory analysis also showed that the samples added with L. plantarum at $30^{\circ}C$ had significantly higher odor, taste and acceptability scores than those fermented at lower temperatures. Under the same processing condition, although the L. plantarum showed slightly lower acidification than the commercial starter culture, however, it significantly improved the eating quality of the product.