• Korean Journal of Food Science and Technology
• /
• v.39 no.1
• /
• pp.71-76
• /
• 2007

Foodborne illness caused by Noroviruses (NVs) is increasing rapidly in Korea. This study developed an effective detection protocol for NVs found in contaminated oysters and lettuce through an investigation using the major steps of virus particle separation, concentration and RT-PCR. As a surrogate model for NVs, the cultivable feline calicivirus (FCV) that belongs to the same Caliciviridae family was used. Instead of using a time-consuming ultracentrifugation method, efficient methods based on solvent extraction and PEG precipitation procedure were applied. Direct homogenization of a 25g sample of whole oyster and lettuce in 175mL PBS provided the simplicity that would be needed in the actual field of food product examination. The overnight PEG precipitation step at $4^{\circ}C$ was reduced to 3 h by placing the reaction tube in ice and by adjusting the PEG concentrations. The application of the use of chloroform and 0.2 ${\mu}m$ syringe filtration together showed a better detection efficiency than the use of chloroform alone in removing PCR inhibitors for both oyster and lettuce samples. Also, dilution of the extracted RNA solution before PCR provided increased sensitivity. The improved detection protocol developed in this study could be efficiently applied to detect FCV and most likely NVs from oysters and lettuce.

• The korean journal of orthodontics
• /
• v.25 no.5 s.52
• /
• pp.605-611
• /
• 1995

The purpose of this study was to evaluate effects of time on shear bond strengths of a light-cured glass ionomer cement and chemically cured resin cement to enamel, and to observe the failure patterns of bracket bondings. Shear bond strength of a light-cured glass ionomer cement were compared with that of a resin cement. Metal brackets were bonded on the extracted human bicuspids. Specimens were subjected to a shear load(in an Instron machine) after storage at room temperature for 5 and 15 minutes; after storage in distilled water at $37^{\circ}C$ for 1 or 35 days. The deboned specimens were measured In respect of adhesive remnant index. The data were evaluated and tested by ANOVA, Duncan's multiple range test, and t-test, and those results were as follows. 1. The shear bond strength of light-cured glass ionomer cement is higher than that of resin cement at 5 and 15 minutes. 2. The shear bond strengths of both light-cured glass ionomer cement and resin cement increase with time. There was no significant difference in those of both 1 day group and 35 day group 3. Light-cured glass ionomer cement is suitable as orthodontic bracket adhesives

• 전자공학회논문지 IE
• /
• v.46 no.3
• /
• pp.6-11
• /
• 2009

In this paper, manufactured composite nanofiber by electrospinning that make spinning solvent according to weight of PAN/PVdF. PVdF content of composite nanofiber decreases, diameter of fiber decreased. Result that measure contact angle to confirm hydrophile property of PAN/PVdF composite nanofiber, PVdF content increases, could confirm that contact angle with water increases. After leave filter measurement sample for 25 hours in temperature of $40^{\circ}C$, humidity of 85%, result PAN/PVdF composite nanofiber that estimate efficiency could confirm that display performance of HEPA more than 99.95% and ULPA more than 99.999%. And fiber diameter is small, could confirm that filter performance increases. Tensile strength of bulk of PAN/PVdF composite nanofiber was 5-8MPa, expansion 100-300%. And strength and expansion could know that increase according as PVdF's content increases. Tensile strength was 3-8MPa degree after annealing PAN/PVdF composite nanofiber during 2 hours in 120t. Tensile strength was no change almost by annealing, and expansion could know that decrease.

• Journal of Sericultural and Entomological Science
• /
• v.30 no.1
• /
• pp.33-39
• /
• 1988

In the case of white cocoon, the fluorescence colors are classified as a yellowish fluorescence cocoon(Y.F.C.) and a violet fluorescence cocoon(V.F.C.) by exposing to ultra-violet ray. Accordingly, experiments were carried out to investigate the difference of sericin behaviors between Y.F.C. and V.F.C. by measuring the sericin solubility, surface tension and viscosity of the sericin solution. Also, the reelability of two different type of cocoons was investigated in the silk reeling process. The results were summarized as follows; 1. The sericin solubility of Y.F.C. shell is higher than that of V.F.C. shell with the dissolution temperature and time. It is shown that the sericin solubility curves of Y.F.c. and V.F.C. are similar in shape, but the difference of sericin solubility between Y.F.C. and V.F.C. is more significant at higher bath temperature. 2. The initial sericin dissolution curves of Y.F.C. and V.F.C. cocoon shell can be divided by four parts within the range of dissolving time from 5 minutes to 60 minutes. The initial dissolution velocity of Y.F.C. shell is faster than that of V.F.C. but the velocity difference is negligible after 30 minutes of dissolving time. 3. The gelation of V.F.C. sericin solution is faster than that of Y.F.C. at early stage(in the range of 15 minutes to 60 minutes). 4. In the silk reeling process, the reelability of Y.F.C. is better than that of V.F.C. with about 11%. This is mainly due to the higher sericin solubility in Y.F.C. followed by the fast dissolution velocity.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.30 no.5
• /
• pp.834-841
• /
• 1997

A lactic acid bacteria which showed antimicrobial activity was isolated from dairy products and identified as Lactobacillus sp. according to the morphological, physiological and biochemical properties, which was named Lactobacillus sp. SH 7311. The bacteriocin of Lactobacillus sp. GM 7311 showed a broad range of inhibitory spectrum against some gram positive and negative bacteria. Especially, Proteus mirabilis was highly sensitive to bacteriocin and used as indicator strain for further investigation. The optimal condition for the production of bacteriocin was showed on MRS broth at $37^{\circ}C$ and pM 6.0. Bacteriocin production of this strain cultured under optimal condition was increased late logarithmic phase to early stationary phase. This bacteriocin was fully active at the pH range $2.0\~5.0$, also was stable at $100^{\circ}C$ for 60 min. at pH 5.0, But about $40\%$ of bacteriocin activity was diminished by the treatment of acetone, ethanol, iso-butanol and ethyl ether during 2 hours at $4^{\circ}C$.

• Korean Journal of Food Science and Technology
• /
• v.48 no.6
• /
• pp.565-568
• /
• 2016

This study was conducted to soften the tough texture of retorted beef in storage by increasing the water holding capacity (WHC) after pretreatment involving soaking and blanching in a phosphate solution. The yield of pretreated beef, based on weight as an indirect indicator of WHC, soaked in 0.35% (w/w) complex phosphates for 1 h, increased by 5-10%, in contrast to the untreated control in which the rib and shank was heated at $100^{\circ}C$ for 5-40 min. Additionally, strength of mechanical toughness in the fore rump and rib after phosphate curing at $115^{\circ}C$ for 30 min and blanching at $100^{\circ}C$ for 2 min were significantly decreased to 1.3 and $1.4kg_f$ (p<0.05) as compared to 2.0 and $1.8kg_f$ in the control, respectively. During storage of retorted beef for 30 days at $10^{\circ}C$, rib and shank pretreated with 0.35% complex phosphates exhibited a highly soft texture as compared to that of untreated beef. The softening of pretreated beef was based on the increased WHC due to complex phosphates.

• Korean Journal of Food Science and Technology
• /
• v.27 no.2
• /
• pp.241-245
• /
• 1995

Focusing on quality problems of delayed chilling porcine muscle, the effects of delayed chilling and aging on the contents of ATP-related compounds and taste of pork were investigated. Twelve Landrace pigs were employed and bisected: left sides were delay-chilled(DC) at room temperature($20^{\circ}C$) for 3 hrs, whereas right sides were conventionally chilled(CC). ATP-related compounds tested were adenosine triphosphate(ATP) and its derivatives in pork muscle, inosine monophosphate(IMP), guanosine monophosphate(GMP) and L-glutamate in cooked broth. DC sides showed more rapid pH decline and degradation of nucleotides than did CC sides. The levels of ATP and adenosine monophosphate(AMP) were not changed significantly. However, adenosine diphosphate(ADP) and IMP showed the highest levels at the 1st and 5th day, respectively. Hypoxanthine(Hx) was gradually increased(p<0.05) during aging. During aging, the IMP contents cooked broth tended to decrease, while the GMP and L-glutamate contents increase. As a result of these, the taste score got better and finally the results of sensory evaluation became increased(p<0.05). However, compared to CC sides, DC sides did not seem to lower taste of pork.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.38 no.2
• /
• pp.139-150
• /
• 1993

This experiment was carried out to investigate the difference of seed vigor according to seed size, and the physiological aspects and physico-chemical phenomena related with seed vigor in soybean cultivars. Portion of seed coat and radicle to entire seed was much higher in cultivars with small seed than with large. Seed coat rate ranged 7.9% to 9.9%, and radicle 2.5% to 3.3% in small seed group, Whereas in large seed, seed coat rate did 5.5-6.4% and radicle, 1.5 to 2.1%. After accelerated aging treatment, there are significant difference in germination ability between seed size. The germination rate after aging ranged 47 to 80% in cultivars with small seed, but in large seed, only 14 to 24%. After seed was carried out dehydration in incubator at 25 after soaking for 6 hours, the moisture content of seed in drying for 12 hour was 25.5% in small seed, while it was 51% in large seed. Electrical conductivity, leaching soluble nitrogen and sugar content were higher in large seed cultivars. Besides, cotyledon damage after soaking was occurred frequently in large seed cultivars, and seed vigor within same cultivars was higher in small seed than large.

• Korean Journal of Food Science and Technology
• /
• v.27 no.1
• /
• pp.19-24
• /
• 1995

The effect of several inhibitors such as ascorbic acid on the lipoxygenase in soybeans known to catalyze reaction resulting in racid off-flavors was examined in the soybean homogenates by the oxygen electrode method. Among 8 compounds added at homogenizing process, 10 mM ascorbic acid inhibited lipoxygenase-1 and lipoxygenase-2/3 activities to 41.7 and 49.8%, respectively. Inactivation of lipoxygenase-2/3 was highly accelerated by homogenization for 15 min at room temperature, so the activity was inhibited 70.8% comparing with the homogenization of 3 min. When soybean homogenates with 10 mM ascorbic acid was stored at $25^{\circ}C$ for 72 hrs, lipoxygenase-2/3 activities lowered to 52.8% whereas L-1 activities lowered to 15.8%. Since it is reported that lipoxygenase-2 is responsible for the off-flavor of soybean products, the inhibitory effect of ascorbic acid among several inhibitors investigated might be useful in soybean processing.

• Journal of the Korean Chemical Society
• /
• v.39 no.6
• /
• pp.459-465
• /
• 1995

Acetolactate Synthase (ALS) was partially purified from the yeast and its basic biochemical studies were carried out. Yeast was grown in the minimum media containing 0.5% glucose, 51 mM $K_2HPO_4$, 22 mM $KH_2PO_4$, 8 mM $(NH_4)2SO_4,\;0.4\;m M\;MgSO_4$ for 18 hours at 37 $^{\circ}C$. The cell was ruptured in the buffer (20 mM phosphate buffer pH 7.0, 0.1 mM TPP, 0.5 mM DTT, 1 ${\mu}M$ FAD, and 1 mM MgCl_2$) following an overnight suspension. The supernatant fraction was collected from $10,000{\times}g$ and the enzyme was further purified by ammonium sulfate fractionation, DEAE-Sephacel chromatography and leucine-agarose chromatography. The enzyme activity was measured under the various conditions by the function of protein concentration, time, temperature, pH, and substrate. The optimum temperature was found to be 50$^{\circ}C$, optimum pH 8.0∼8.5. The kinetic parameters, $K_m\;and\;V_{max}$ were 8.4 mM and 17.9 nmol/mg/min respectively. Stability of the enzyme was studied with ethylene glycol and glycerol added to the enzyme solution. Both ethylene glycol and glycerol improved the enzyme stability up to 50%. The study of feedback inhibition showed that valine was a strong inhibitor while leucine was a weak inhibitor.