• Journal of the Korean Wood Science and Technology
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• v.52 no.3
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• pp.205-220
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• 2024

Various polylactic acid (PLA) blends were reinforced with untreated or silane-treated micro-sized cellulose fiber (MCF), successfully prepared as 3D printing filaments and then printed using a fused filament fabrication (FFF) 3D printer. In this study, we focused on developing 3D-printed MCF/PLA composites through silane treatment of MCF and investigating the effect of silane treatment on the various properties of FFF 3D-printed composites. Fourier transform infrared spectra confirmed the increase in hydrophobic properties of silane-treated MCF by showing the new absorption peaks at 1,100 cm^-1, 1,030 cm^-1, and 815 cm^-1 representing C-NH₂, Si-O-Si, and Si-CH₂ bonds, respectively. In scanning electron microscope images of silane-treated MCF filled PLA composites, the improved interfacial adhesion between MCF and PLA matrix was observed. The mechanical properties of the 3D-printed MCF/PLA composites with silane-treated MCF were improved compared to those of the 3D-printed MCF/PLA composites with untreated MCF. In particular, the highest tensile and flexural modulus values were observed for S-MCF10 (5,784.77 MPa) and S-MCF5 (2,441.67 MPa), respectively. The thermal stability of silane-treated MCF was enhanced by delaying the initial thermal decomposition temperature compared to untreated MCF. The thermal decomposition temperature difference at T₉₅ was around 26℃. This study suggests that the effect of silane treatment on the 3D-printed MCF/PLA composites is effective and promising.

• New & Renewable Energy
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• v.18 no.2
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• pp.9-17
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• 2022

In this study, we used the Flux Balance Analysis (FBA) program to examine the behavior of hydrogen and organic acids according to seasonal changes in food wastewater collected from D city. The results showed that average hydrogen conversion rates in spring, summer, autumn, and winter were 1.06, 0.71, 1.21, and 1.13 mol H₂/mol of hexose_added, respectively, indicating a significantly lower hydrogen conversion rate in summer than in other seasons. This phenomenon is believed to occur because the carbohydrate concentration of the incoming food wastewater is low. In addition, Lactobacillus, the lactic acid-producing bacterium, was 21.3% in spring, 27.2% in summer, 17.5% in autumn, and 22.6% in winter. The most distinctive feature of the microbial community in summer was that 15.3% of the Ilyobacter was analyzed. It was confirmed that Ilyobacter, which is involved in the production of acetic acid and propionic acid, is closely associated with the tendency of increasing acetic acid and propionic acid and thus contributes to organic acid change. Clostridium, a hydrogen-producing bacterium, was 76.2%, 50.8%, 78.3%, and 74%, in spring, summer, autumn, and winter, respectively. It was confirmed that Clostridium dominates the microbial community by approximately 70% or more in all seasons except summer.

• Korean Journal of Food Science and Technology
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• v.41 no.5
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• pp.503-508
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• 2009

The principal objective of this study was to evaluate the physicochemical properties and volatile compound contents of Moju acquired from 12 restaurants in Jeonju. The alcohol contents were lower than 2.1%, and the pH values ranged from 3.85 to 4.38. Total acidity, $^{\circ}Bx$, and UV absorbance values differed among the samples according to the type of side materials added. Reducing sugar contents were found to be substantially superior to other commercial takju variants. Malic and lactic acid contents were higher than the contents of other organic acids, and the free sugar contents were as follows: maltose>glucose>fructose. Overall, the high b (yellowness) and cP values were attributable to the turbid yellow and heavy condition of the samples. The volatile compound contents of Moju were analyzed via GC and GC/MSD. 30 components were identified, including 3 alcohols, 12 esters, 7 hydrocarbons, and 4 aldehydes. Among the alcohol compounds, benzeneethanol levels were higher than the levels of isoamyl alcohol. Ethyl caprate, ethyl palmitate, and ethyl linoleate, which were fundamentally attributable to origin liquor, were highest among the 12 esters. (E)-cinnamaldehyde, which was the most abundant among 7 hydrocarbons, and (E)-cinnamyl acetate contents were attributed to the presence of cinnamon, a common supplement in the processing of Moju.

• Korean Journal of Poultry Science
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• v.35 no.1
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• pp.57-62
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• 2008

The study was conducted to evaluate the effects of dietary organic acid mixture(lactic acid 12%, formic acid 9%, citric acid 5%, butyric acid 5% and phosphoric acid 6%) on growth performance, organ weight, blood immunological parameter and intestinal villi morphology in broilers. Dietary treatments included 1) CON (basal diet), 2) OA1 (basal diet + 0.1% organic acid mixture) and 3) OA2 (basal diet + 0.2% organic acid mixture). Four hundred eighty hatched Arbor Acre broiler chickens were housed in 24 pens of 20 birds each. Eight replicate pens were allotted into each treatment by completely randomized design. Daily weight gain, feed intake and feed/gain were not significantly different among the treatments. In organ weight, that of gizzard was significantly heavier in OA2 than CON (Linear effect = 0.034). However, those of spleen and intestine were not significantly different among the treatments. Blood immunological parameters such as RBC, WBC and lymphocyte were not significantly difference. In intestinal villi morphology, villi length was increased in OA1 compared to CON (Quadratic effect = 0.050). In conclusion, 0.2% organic acid mixture was effective to improve gizzard weight of broilers.

• Macromolecular Research
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• v.14 no.5
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• pp.510-516
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• 2006

Lactide was produced from oligomeric PLA by back-biting reaction of the OH end groups. For optimization of the reaction conditions, the effects of temperature, pressure, PLA molecular weight, and catalyst type on the lactide synthesis were examined. The fraction of D,L-lactide decreased with increasing temperature. Among the various Sn-based catalysts, the D,L-lactide fraction was maximized when SnO was used. A higher yield with lower racemization was observed at lower pressure. The conversion of PLA was maximized at an oligomeric PLA molecular weight of ca. 1380. The yield of lactide increased but the fraction of D,L-lactide decreased with increasing molecular weight. The highest conversion with the lowest racemization degree was obtained at a catalyst concentration of 0.1 wt%. The lactide was more sensitive to racemization because of the entropic effect.

• Journal of Animal Science and Technology
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• v.51 no.6
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• pp.511-520
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• 2009

The purpose of this study was to investigate effects of increased levels of eugenol, thymol and malate on pH and the concentrations of VFA, lactate and ammonia-N during in vitro ruminal incubation. One Hanwoo beef steer (741 kg) fitted with a rumen cannula was used and fed 0.5 kg/day rice straw and 10 kg/day corn-based concentrate (ratio of concentrate to rice straw = 95 : 5 on DM basis). Three different doses of thymol, eugenol and malate were used. Treatments of the experiment were as follows: Treatments of thymol were control (1g D-glucose/40ml), T1 (1g D-glucose + 40 mg thymol/40 ml), T2 (1g D-glucose + 50 mg thymol/40 ml) and T3 (1g D-glucose + 60 mg thymol/40 ml). Treatments of eugenol were control (1g D-glucose/40 ml), E1 (1g D-glucose + 55 mg eugenol/40 ml), E2 (1g D-glucose + 65 mg eugenol/40 ml) and E3 (1g D-glucose + 75 mg eugenol/40 ml). Treatments of malate were control (1g D-glucose/40ml), M1 (1g D-glucose + 25 mg malate/40ml), M2 (1g D-glucose + 50 mg malate/40 ml) and M3 (1g D-glucose + 100 mg malate/40 ml). The results of this study showed that eugenol and thymol have improved stability of the ruminal fermentation by decreasing lactic acid concentration and increasing ruminal pH. However, it inhibited the production of total VFA, acetate and propionate. Malate also improved stability of the ruminal fermentation by decreasing lactic acid concentration and increasing ruminal pH, but it had a very little effect on ruminal lactate concentrations and pH. On the other hand, malate did not decrease the concentrations of total VFA, acetate and propionate. Therefore, at the low ruminal pH expected in high-concentrate diets, thymol, eugenol, and malate are potentially useful in Hanwoo finishing diets. Further studies are necessary for determining the effectiveness of these additives on in vivo rumen fermentation and animal performance in Hanwoo finishing steers.

• Proceedings of the SCSK Conference
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• 2003.09b
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• pp.519-523
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• 2003

Alpha hydroxy acid (AHA) includes a group of organic acids found in natural foods such as sugarcane (glycolic acid), milk (lactic acid), apples (malic acid) and oranges (citric acid). Earlier studies demonstrated the effect of AHAs on the skin by diminishing the adhesiveness of the corneal layer and increasing the viable epidermal thickness. Recent data suggest that AHAs have some effects on the dermal component of skin and even affect the aging process of the skin. A previous study revealed increased collagen production by treatment with glycolic acid among AHAs in vitro. However, the mechanism of the regulation of collagen production by glycolic acid was unclear. In present study, we tried to demonstrate the effect of glycolic acid on human dermal fibroblasts and to unveil the mechanism of regulation of collagen production by glycolic acid in human dermal fibroblasts: proliferation of fibroblasts and collagen synthesis and degradation by collagenases in fibroblasts. Our results suggested that glycolic acid had no effect on proliferation and cytotoxicity of adult human dermal fibroblasts. However, glycolic acid not only induced the increase of the collagen synthesis in human dermal fibroblasts at lower concentration than 0.1 % but also inhibited MMP-2 activity of human dermal fibroblast in the range between 0.01 and 0.4% and MMP-9 activity of human dermal fibroblast in the range between 0.06 and 0.09%. In summary, our results suggest that glycolic acid may increase wrinkle reduction partially by both increase in collagen synthesis and decrease in collagen degradation.

• Animal Bioscience
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• v.34 no.6
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• pp.1029-1037
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• 2021

Objective: This study was conducted to investigate effects of antifungal substance and carboxylesterase-producing inoculant on fermentation indices and rumen degradation kinetics of whole crop rice (WCR) silage ensiled at different dry matter (DM) contents. Methods: Dual-purpose inoculants, Lactobacillus brevis 5M2 and Lactobacillus buchneri 6M1, confirmed both activities of antifungal and carboxylesterase in the previous study. The WCR at mature stage was chopped, and then wilted to obtain three different DM contents consisting of 35.4%, 43.6%, and 51.5%. All WCR forages were applied distilled water (CON) or mixed inoculants with 1:1 ratio at 1×105 colony forming unit/g (INO), and ensiled into 20 L mini silo (5 kg) in quadruplicates for 108 d. Results: The INO silages had lower lactate (p<0.001) and butyrate (p = 0.022) with higher acetate (p<0.001) and propionate (p<0.001) than those of CON silages. Ammonia-N (p<0.001), lactate (tendency; p = 0.068), acetate (p = 0.030), and butyrate (p<0.001) concentrations of INO silages decreased linearly with increasing DM content of WCR forage. The INO silages presented higher lactic acid bacteria (p<0.001) with lower molds (p<0.001) than those of CON silages. Yeasts (p = 0.042) and molds (p = 0.046) of WCR silages decreased linearly with increasing DM content of WCR forage. In the rumen, INO silages had higher the total degradable fraction (p<0.001), total volatile fatty acid (tendency; p = 0.097), and acetate (p = 0.007), but lower the fractional degradation rate (p = 0.011) and propionate (p<0.001) than those of CON silage. The total degradable fraction (p<0.001), total volatile fatty acid (p = 0.001), iso-butyrate (p = 0.036), and valerate (p = 0.008) decreased linearly with increasing DM content of WCR forage, while the lag phase (p<0.001) was increased linearly. Conclusion: This study concluded that application of dual-purpose inoculants on WCR silage confirmed antifungal and carboxylesterase activities by inhibiting mold and improving rumen digestibility, while increase of wilting times decreased organic acids production and rumen digestibility.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.1
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• pp.10-17
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• 2017

The natural preservative "complex Scutellaria baicalensis extract (BHC)" contains Scutellaria baicalensis, Glycyrrhiza uralensis (liquorice), Zizyphus jujube (jujube), and Astragalus propinquus (milk vetch root). BHC has been used as a natural preservative for more than 10 years to increase storage duration and quality of food with strong antibacterial activity. BHC has been added into functional foods as a subsidiary ingredient. However, no studies have been performed to test whether or not BHC affects the activity of main functional ingredients. In this study, we tested whether or not BHC has any effect on the hepatoprotective activity of lactic acid-fermented garlic extract (LAFGE) when formulated in a clinical test supplement. $H_2O_2-induced$ oxidative damage in HepG2 cells was not attenuated by BHC, indicating that BHC had no influence on the protective effect of LAFGE against oxidative damage. Furthermore, BHC had no effect on the hepatoprotective effect of LAFGE against acetaminophen-induced acute liver injury in rats, as indicated by no changes in alanine transaminase and aspartate transaminase levels. In conclusion, BHC, formulated in the clinical test supplement with LAFGE, had no effect on hepatoprotective activity, indicating BHC could be considered as a suitable natural preservative for liquefied functional food materials.

• Korean Journal of Food Science and Technology
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• v.51 no.2
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• pp.114-119
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• 2019

Seven antimicrobial agents known to be effective in inhibiting the growth of lactic acid bacteria were applied to ensure the microbial safety of low-salted squid and myungran jeotgal with 4-6% salinity. These agents reduced the salt content by 50% compared with the conventional Jeotgal. Lactic acid bacteria such as Lactobacillus sp., Streptococcus sp., and Pediococcus sp. were commonly found to account for 80% of microbial organisms, and yeast and fungi were observed in squid and myungran jeotgal, respectively. The total bacterial counts in squid and myungran jeotgal showed 94.20 and 90.87% reduction after the addition of 0.5% (w/w) glycine. The microbial counts in squid and myungran jeotgal decreased $10^1-10^2CFU/g$ when compared with the control after 21 days at $10^{\circ}C$. Glycine was found to be an effective commercial antimicrobial agent that can be used to control bacterial count in low-salted Jeotgal without affecting sensory qualities such as overall taste and flavor.