• Applied Biological Chemistry
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• 제33권1호
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• pp.73-78
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• 1990

Endo-polygalacturonase was purified from tomato, Lycopersicon esculentum L. The purification procedures included gel filtration on Sephadex G-150 and DEAE-cellulose ion exchange chromatography. Yield of the enzyme purification was 12.74 %. Purified enzyme was confirmed as a active single band by the SDS-polyacrylamide gel electrophoresis. When the purified enzyme was applied to SDS-PAGE, the molecular weight was estimated about 50,000. The optimum pH for the enzyme activity was 5.0 and the range of its stability to the pH was 4.0 to 5.0. The optimum temperature was $50^{\circ}C$, while the enzyme was abruptly inactivated above $50^{\circ}C$. From the result of the study on the effects of metals ion, it was found that $Ag^+$, $Zn^{++}$ and $Mg^{++}$ increased on the enzyme activity. In contrast, $Ba^{++}$, $Hg^{++}$, $Pb^{++}$, $Ca^{++}$, $Mn{++}$, $Cu^{++}$, $Fe^{+++}$, $Na^+$ and $K^+$ decreased it. the reaction catalyzed by this enzyme followed typical Michaelis-Menten kinetics with the Km value of $1.43{\times}10^{-1}\;mol/l$.

• Microbiology and Biotechnology Letters
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• 제14권6호
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• pp.447-453
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• 1986

The culture filtrate of thermophilic alkalophilic Bacillus K17 strain contained two types of xylanases were purified by ammonium sulfate fractionation, DEAD-Sephadex A-50 column chromatography, CM-Sephadex C-50 column chromatography and Sephadex G-100 gel filtration. The purified enzymes were found to be homogeneous by sodium dodecyl sulfate and disc polyacrylamide gel electrophoresis. Xylanase I and II were characterized with respect to molecular weight, optimal temperature and pH, thermal and pH stability, and Michaelis constant. Xylanase II was more active and stable, and showed greater substrate affinity and molecular weight than xylanase I. The activities of xylanases I and II were inhibited by Cu$^{++}$, Ag$^+$, Hg$^{++}$ and Fe$^{++}$. Xylanase I hydrolyzed xylan to yield xylobiose and higher amount of xylooligosaccharides, but xylanase II produced xylose other than xylobiose and xylooligosacchrides.

• Microbiology and Biotechnology Letters
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• 제36권2호
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• pp.128-134
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• 2008

In order to examine efficient L-threo-2,3-Dihydroxyphenylserine (L-threo-DOPS) synthesis process using whole cell biocatalyst, a thermostable L-threonine aldolase (L-TA), which cloned from Streptomyces coelicolor A3(2) and improved for stability, was expressed in a Corynebacterium glutamicum R strain. The constructed Corynebacterium expression vector, pCG-H44(1) successfully expressed L-TA in C. glutamicum R strain, but showed very low expression level. In order to improve the expression level, the expression vector named pCG-H44(2) was reconstructed by eliminating 1 nucleotide between SD sequence and start codon of L-TA. The pCG-H44(2) vector plasmid was able to overexpress L-TA approximately 3.2 times higher than pCG-H44(1) in C. glutamicum R strain (CGH-2). When the whole cell of CGH-2 was examined in a repeated batch system, L-threo-DOPS was successfully synthesized with a yield of 4.0 mg/ml and maintain synthesis rate constantly after 30 repeated batch reactions for 130 h.

• Journal of Fisheries and Marine Sciences Education
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• 제20권1호
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• pp.135-145
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• 2008

Biogenic amines are naturally occurring anti-nutrition factors. They are causative agents in food poising episodes and act as catalysts to allergic reactions. The most commonly occurring biogenic amines in foods are: Histamine, tyramine, putrescine, cadaverine, tryptamine, ${\beta}$-phenylethylamine, spermine, spermidine and agmatine. The objective of this study was to identify changes and content levels of specific biogenic amines at selected storage temperatures $20{^{\circ}C}$, $4{^{\circ}C}$, and $-25{^{\circ}C}$, respectively. This study will focus on histamine, cadaverine, and putrescine concentrations in the following dark-fleshed fishes: Mackerel (Scomber japonicus), Horse Mackerel (Trachurus japonicus), Mackerel Pike (Cololabis saira), and Spanish Mackerel (Scomberomorus niphonius). Biogenic amines were determined using a method based on an extraction procedure described in the derivatisation and HPLC(High Performance Liquid Chromatography). The the recovery rate of individual amines was higher than those found in ion exchange chromatography. The results from the dark fleshed fish stability trial showed that high content of histamine (cadaverine and putrescine) were produced within a short period of time at $20{^{\circ}C}$. Fish stored at lower temperatures $4{^{\circ}C}$, showed lower content of biogenic amines. At $-25{^{\circ}C}$ the production of histamine, cadaverine and putrescine did not initiate until after day 100. All fish recorded the content of histamine below 1 mg/kg with the exception of the Horse Mackerel.

• Journal of the East Asian Society of Dietary Life
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• 제17권5호
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• pp.615-625
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• 2007

This study investigated the overall conditions related to family meals, including perceptions, attitudes, and behaviors, among middle and high school students. The data were collected from 773 male and female students attending middle and high schools in Seoul and Kyunggi-Do from March to May 2006, using pre-tested self-administered questionnaires. The results are as follows: 78.9% of the subjects lived with their parents and siblings, and 75.7% regarded family meals as meals eaten with all family members living together in a household. As for the frequency of family meals, 40.1% of the middle school subjects answered that they ate with their family 'more than once per day' and 20.8% answered '1 or 2 time per a week'. However 21.0% of the high school students had family meals 'more than once per day', and 31.7% had family meals '1 or 2 times per a week', showing a significant difference between the groups(p<0.001). When the degree of satisfaction with life was evaluated using a Likert scale(strongly satisfied 5 point, strongly unsatisfied 1 point), the middle school students showed a significantly higher level of satisfaction than the high school students towards daily life, health, nutritive conditions, and family care. feelings, attitudes, and behaviors toward family meals were also evaluated(strongly agree 5 point, strongly disagree 1 point), and the results showed that the subjects had positive psychological feelings, with significant differences based on the frequency of family meals. Likewise, the groups who ate frequent family meals scored higher on aspects related to having positive attitudes and behaviors toward the family meal, implying that eating family meals is associated with promoting friendship, psychological stability, and positive thinking in adolescents. These findings suggest that attention needs to he directed toward increasing the frequency of family meals and creating a positive family meal environment.

• Asian-Australasian Journal of Animal Sciences
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• 제28권5호
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• pp.620-631
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• 2015

A total of 59 lactic acid bacteria (LAB) strains were isolated from corn stover silage. According to phenotypic and chemotaxonomic characteristics, 16S ribosomal DNA (rDNA) sequences and recA gene polymerase chain reaction amplification, these LAB isolates were identified as five species: Lactobacillus (L.) plantarum subsp. plantarum, Pediococcus pentosaceus, Enterococcus mundtii, Weissella cibaria and Leuconostoc pseudomesenteroides, respectively. Those strains were also screened for antimicrobial activity using a dual-culture agar plate assay. Based on excluding the effects of organic acids and hydrogen peroxide, two L. plantarum subsp. plantarum strains ZZU 203 and 204, which strongly inhibited Salmonella enterica ATCC $43971^T$, Micrococcus luteus ATCC $4698^T$ and Escherichia coli ATCC $11775^T$ were selected for further research on sensitivity of the antimicrobial substance to heat, pH and protease. Cell-free culture supernatants of the two strains exhibited strong heat stability (60 min at $100^{\circ}C$), but the antimicrobial activity was eliminated after treatment at $121^{\circ}C$ for 15 min. The antimicrobial substance remained active under acidic condition (pH 2.0 to 6.0), but became inactive under neutral and alkaline condition (pH 7.0 to 9.0). In addition, the antimicrobial activities of these two strains decreased remarkably after digestion by protease K. These results preliminarily suggest that the desirable antimicrobial activity of strains ZZU 203 and 204 is the result of the production of a bacteriocin-like substance, and these two strains with antimicrobial activity could be used as silage additives to inhibit proliferation of unwanted microorganism during ensiling and preserve nutrients of silage. The nature of the antimicrobial substances is being investigated in our laboratory.

• Korean Journal of Food Science and Technology
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• 제17권4호
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• pp.265-270
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• 1985

The saponin yield and its compositional changes of red ginseng extract (RG-EXT) was investigated during extraction at various temperature for 5 times of 8 hours. The higher temperature resulted an increase in solids yield while the total saponin recovered was decreased, particularly at $100^{\circ}C$. A relatively lower thermal stability was found for protopanaxadiol saponin, one of the saponin fractions, than protopanaxatriol saponin. The compositional ratio of saponin at ginsenoside level was little affected by extraction time. The yields data showed that more than 94% of total saponin was recovered by 3$\sim$4 times of 8 hours extraction. Extraction at $80^{\circ}C$ for 4 times of 8 hours were suggested for preparation of RG-EXT from the result of this work.

• Food Science of Animal Resources
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• 제31권1호
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• pp.9-18
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• 2011

This study was aimed at comparing the pH, color, thiobarbituric acid (TBA), volatile basic nitrogen (VBN), textural properties, and sensory evaluations of chicken meat patties containing lotus (Nelumbo nucifera) leaf powder, and assessing their shelf-life at refrigeration temperature ($4{\pm}1^{\circ}C$). In the refrigerated storage, the pH, lightness, yellowness, springiness values, and sensory properties scores of the control as well as all the treated samples decreased as the storage increased. The hardness, gumminess, chewiness, TBA, and VBN-values of control and all the samples treated with lotus leaf increased during refrigerated storage. At the end of the storage period (day 28), chicken patties containing lotus leaf powder had lower pH, redness, yellowness, TBA, VBN, hardness, gumminess, and chewiness values than those of control. The results of this study showed that a lotus leaf powder can increase storage stability in chicken meat products.

• Korean Journal of Food Science and Technology
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• 제30권5호
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• pp.1064-1069
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• 1998

Tetrasodium polyphosphate peroxidate (TPP) increased the farinograph stability, maximum resistance by extensigraph and amylograph peak viscosity of a noodle flour produced from Australian Standard White wheat (protein 8.76%, ash 0.380%) at concentration of $0.2{\sim}0.4%$ based on flour weight. The addition of 0.3% TPP increased the moisture content of Kalguksoo, handmade fresh noodle, by 1.5%. No significant differences however were observed in cooking properties. Sensory evaluation revealed that the color, texture and preference of cooked noodle were significantly better in the presence of TPP. The fresh noodle with 0.3%, TPP delayed the development off-flavor by 7 hr during storage at $20^{\circ}C$ and $25^{\circ}C$.

• Korean Journal of Food Science and Technology
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• 제40권1호
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• pp.118-121
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• 2008

Guar gum, ${\kappa}$-carrageenan, alginic acid and chitosan were applied to pork as a model system, and evaluated as a substitute for inorganic polyphosphate, which is one of the essential additives in conventional meat processing. The tested materials did not alter the fat content or pH of the pork meat; however, they did affect water holding capacity and cooking loss significantly. The pork with added guar gum and ${\kappa}$-carrageenan exhibited lower cooking loss than the pork with added polyphosphate. Also, theses materials showed no negative coloring effect within the pork meat blends, which suggest the possibility for their application in final products. In addition, the pork processed with guar gum showed a similar emulsion stability to that with polyphosphate. Overall, guar gum and ${\kappa}$-carrageenan were confirmed as possible substitutes for inorganic polyphosphate.