• Macromolecular Research
• /
• v.11 no.1
• /
• pp.14-18
• /
• 2003

Grafting of glycidyl methacrylate (GMA) upon coralline hydroxyapatite in conjugation with demineralized bone matrix (CHA-DBM) using equal molar ratio of potassium persulfate/sodium metabisulfite redox initiating system was investigated in aqueous medium. The optimum reaction condition was standardized by varying the concentrations of backbone, monomer, initiator, temperature and time. The results obtained imply that the percent grafting was found to increase initially and then decrease in most of the cases. The optimum temperature and time were found to be 50 $^{\circ}C$ and 180 min, respectively, to obtain higher grafting yield. Fourier transform infrared (FT-IR) spectroscopy and X-ray powder diffraction (XRD) method were employed for the proof of grafting. The FT-IR spectrum of grafted CHA-DBM showed epoxy groups at 905 and 853 $cm^{-1}$ / and ester carbonyl group at 1731 $cm^{-1}$ / of poly(glycidyl methacrylate) (PGMA) in addition to the characteristic absorptions of CHA-DBM, which provides evidence of the grafting. The XRD results clearly indicated that the crystallographic structure of the grafted CHA-DBM has not changed due to the grafting reaction. Further, no phase transformation was detected by the XRD analysis, which suggests that the PGMA is grafted only on the surface of CHA-DBM backbone. The grafted CHA-DBM will have better functionality because of their surface modification and hence they may be more useful in coupling of therapeutic agents through epoxy groups apart from being used as osteogenic material.

• Fisheries and Aquatic Sciences
• /
• v.25 no.2
• /
• pp.64-75
• /
• 2022

This study aimed to investigate the effect of different coating materials on the quality of shrimp (Litopenaeus vannamei) during chilled storage for 10 days. Fresh shrimp were randomly divided into five groups: the control group, the hypotaurine treatment group (2%), the chitosan group (1%), the hypotaurine + chitosan group (2% hypotaurine solution with 1% of chitosan), and the sodium metabisulfite treatment group (1.25%). Compared with other treatments, the lower accumulation of total visible counts (TVC, 5.25 Log₁₀ CFU/g), total volatile basic nitrogen (TVB-N, 22.5 mg/100 g) and thiobarbituric acid values (TBA, 0.58 mg MDA/kg) suggested that coating of chitosan-hypotaurine could retard the microbial activity, protein degradation and lipid oxidation of shrimp. Meanwhile, results demonstrated that the chitosan coating combined with hypotaurine showed an excellent performance in inhibiting quality deterioration (pH 7.5, ∆E 7.0, hardness 393 g, and elasticity 0.69). Furthermore, the melanosis degree of shrimp was alleviated, and the sensory parameters, including appearance, odor and texture, were maintained to the acceptable level by chitosan based hypotaurine treatment during the chilled storage.

• Applied Biological Chemistry
• /
• v.30 no.3
• /
• pp.278-284
• /
• 1987

As a basic research for inhibition of enzymatic browning of apples during dehydration or processing, polyphenol oxidase was extracted from Fuji apples to investigate heat inactivation, chemical inhibition and other properties. Polyphenol oxidase showed the highest activity at $20^{\circ}C$ and pH 5.5 with catechol as substrate, and the Michaelis constant of 0.14 M under the same condition of substrate and pH. The thermal inactivation followed pseudo first-order kinetics to have activation energy of 23.0 kcal/mol and z value of $19.7^{\circ}C$. As for substrate specificity the polyphenol oxidase showed high affinity toward the o-diphenolic compounds, particularly chlorogenic acid. Neither the m- and p-dihydroxy phenols nor monophenols were attacked. Browning by polyphenol oxidase was completely inhibited at the concentrations of 10mM for potassiummetasulfite and thiourea and 1mM for L-cysteine, ascorbic acid and sodium diethyldithiocarbamate.

• Korean Journal of Pharmacognosy
• /
• v.22 no.2
• /
• pp.101-111
• /
• 1991

Polyphenol oxidase(PPO) was purified from an extract of Puerariae Radix by ammonium sulfate fractionation followed by Sephadex G-150 column chromatography, which resulted in a 56-fold increase in specific activity. The enzyme was optimum of pH 6.5. The optimum temperature of enzymic reaction was about $40^{\circ}$. The enzyme was thermostable with a half-life equal to 32 min at $70^{\circ}$. Km values of the PPO for catechol and pyrogallol from Lineweaver Burk plots were $1.3{\times}10^{-2}M$, $1.16{\times}10^{-2}M$, respectively. The substrate specificity of the Puerariae Radix PPO showed high affinity toward pyrogallol. Reducing reagents such as cysteine, potassium metabisulfite, ascorbic acid, 2-mercaptoethanol completely inhibited the PPO activity at $10^{-2}M$ level. Linewear-Burk analysis of inhibition data revealed that the inhibition by cysteine, 2-mercaptoethanol, 4-nitrocatechol, potassium cyanide was competitive with Ki values of $4.3{\times10^{-2}M,\;0.73{\times}10^{-6}M,\;6.9{\times}10^{-6}M,\;6.4{\times}10^{-7}M$, respectively. The browning reaction by PPO was observed to decrease temporarily with the addition of sodium diethyl dithiocarbamate, a well known copper chelating agent. Among the divalent cations, $Cu^{2+}$ ion was strong activator on PPO and $Mn^{2+},\;Co^{2+}$ ions was effect on PPO activity. $Zn^{2+},\;Mg^{2+}$ ions was inhibitor on PPO.

• Korean Journal of Pharmacognosy
• /
• v.30 no.3
• /
• pp.306-313
• /
• 1999

Polyphenol Oxidase(PPO) was purified from an extract of Ginkgo biloba leaves by ammonium sulfate fractionation followed by sephadex G-150 column chromatography, which resulted in a 18-fold increase in specific activity. The enzyme was most active at pH 8.5 and the temperature optimum for the PPO catechol oxidation reaction was $45^{\circ}C$. Heat inactivation studies showed that heating for 7, 9 and 48 min, at 80, 70 and $60^{\circ}C$ respectively caused a 50% loss in enzymatic activity and that the enzyme was completely inactivated after heat treatment at $90^{\circ}C$ for 60 min. Km values of the PPO for catechol, hydroquinone and 4-methylcatechol derived from Lineweaver-Burk plots were $6.06\;{\times}\;10^{-4}M,\;1.02\;{\times}\;10^{-3}M,\;1.41\;{\times}\;10^{-3}M$ respectively. Of the substrates tested, 4-methylcatechol was oxidized most readily and the enzyme did not oxidize monophenols. The enzyme datalyzed browning reaction was completely inhibited in the presence of reducing reagents, namely ascorbic acid, cysteine, glutathione, 2-mercaptoethanol, potassium metabisulfite at 0.5 mM level. Sodium chloride showed very little inhibition effect on Ginkgo biloba leaves PPO. Lineweaver-Burk analysis of inhibition data revealed that the inhibition by cysteine, 2-mercaptoethanol, potassium cyanide was competitive with ki values of $1.1\;{\times}\;10^{-5}M,\;2.4\;{\times}\;10^{-5}M,\;8\;{\times}\;10^{-5}M$, respectively. Among the divalent cations, $Cu^{2+}ion$ was a strong activator on PPO and $Mn^{2+}ion$ was little or no effect on PPO activity $Ni^{2+}ion$ was an inhibitor on PPO.

• Korean Journal of Food Science and Technology
• /
• v.16 no.4
• /
• pp.413-417
• /
• 1984

To examine enzymatic browning of apple wine, changes of active bands of polyphenol oxidase (EC 1.10.3.1) as well as polyphenol substances related to browning of apple wine were investigated during wine brewing. The decrease of total phenol was remarkably inhibited by the addition of sodium metabisulfite. In the meantime, auto-oxidation of catechol in a model system increased proportionally as the reaction pH and temperature increased. Catechol oxidation, however, was not detected at $4^{\circ}C$ below pH 5.0. Polyacrylamidegel electrophoretic patterns showed that the apple (Jonathan) indicated 4 bands with polyphenol oxidase activity, designated a, b, c and d whose Rm were 0.21, 0.30, 0.41 and 0.51, respectively. Among these, 2 bands, a and c remained until 5th day fermentation and only c band after 6th day fermentation. After pasteurization of apple wine at $60^{\circ}C$ for 30min, c band also remained.

• Korean Journal of Food Science and Technology
• /
• v.35 no.3
• /
• pp.532-535
• /
• 2003

Inhibition effects of enzymatic browning in medical herbs (Paeoniore radix rubra, Pueraria radix, Araliae cordatae radix) by organic acid were investigated. The inhibition effects were in the order of citric acid>ascorbic acid>isoascorbic acid>acetic acid in 1% compound, with no significant difference observed between 1% citric acid and 1% sodium metabisulfite. Results revealed that citric acid was the most effective sulfite substitute agent for the inhibition of enzymatic browning of medical herbs.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.39 no.10
• /
• pp.1476-1480
• /
• 2010

Physicochemical properties of flours prepared from sweet potatoes with different flesh color (white, yellow/orange and purple) were investigated. Sweet potatoes were soaked in solutions of antibrowning agents such as sodium metabisulfite and citric acid, and freeze or hot air-dried prior to grinding to produce sweet potato flours. Sweet potato flours with different flesh colors showed differences in chemical composition. Purplefleshed sweet potato flour had higher protein, ash, and dietary fiber contents that white and yellow/orangefleshed sweet potato flours. Average particle size of yellow/orange-fleshed sweet potato flour was higher than those of white/yellow or purple-fleshed sweet potato flour. Both water absorption index (WAI) and oil absorption capacity of flours prepared from sweet potatoes by hot-air drying were higher than those from sweet potatoes by freeze drying.

• Journal of Radiopharmaceuticals and Molecular Probes
• /
• v.8 no.2
• /
• pp.71-76
• /
• 2022

Indigenous diagnostic dose of ¹³¹I-labeled meta-iodobenzylguanidine ([¹³¹I]mIBG) was prepared via Cu⁺ catalyzed isotope exchange reaction generated in situ by sodium metabisulfite for imaging of neuroblastoma tumor. [¹³¹I]mIBG was produced in overall 85-90% radiochemical yield. The average amount of radioactivity of [¹³¹I]mIBG was 2164 MBq (1998-2331MBq) with an average specific activity > 1000 MBq/mg at the end of synthesis. The radiochemical purity was ≥ 99.9% after purification through Dowex-1 × 8 ion exchange resin (100-150 mesh) at the date of preparation. The stability of [¹³¹I]mIBG at concentration 480-555 MBq/mL was > 97% at 4 ℃ after 4 days. The room temperature (25 ℃) stability of [¹³¹I]mIBG was > 98% after 24 h. Biodistribution of [¹³¹I]mIBG in patient showed uptake in salivary glands, liver, spleen and excreted though urinary bladder. Neuroendocrine medicated uptake into tumor lesion and metastatic sites were noted which strongly correlate with the morphological abnormalities of patient.

• Proceedings of the Plant Resources Society of Korea Conference
• /
• 2020.12a
• /
• pp.74-74
• /
• 2020

고사리(Pteridium aquilinum Kuhn)는 고사리 속(Pteridium spp.)에 속하는 양치식물의 총칭으로서 우리나라에는 22과 70속 272종이 분포되어 있는 것으로 보고되었다. 고사리의 어린 순에는 가식부 100g 당 칼슘 15.0mg, 칼륨 185.0mg 등이 함유되어 있으며 골다공증, 심혈관 질환 등에 효과가 있고 식이섬유로 인해 변비 예방에도 유용한 것으로 알려져 있다. 우리나라의 고사리 재배면적은 2019년 기준 5,349ha 수준을 보이고 있으며 전체 산채류 재배면적에서 26%의 비중을 차지하고 있으나 재배면적의 증가에 따라 고사리 재배의 부가가치를 높일수 있는 방안이 요구되고 있는 실정으로 그 중 고사리 뿌리에서 추출한 전분은 중국 및 일본 등지에서 면류나 제과용으로 이용되고 있어 고사리 재배의 부가가치를 향상시킬 수 있는 방안으로 기대되고 있다. 본 연구에서는 고사리 뿌리의 채취시기에 따른 뿌리 전분의 생산성과 이화학적 특성을 조사하기 위해 2020년 3월 26일부터 10월 28일 까지 5회에 걸쳐 뿌리를 수확하여 세척한 후 고무망치로 파쇄하고 수침 방법을 이용해 추출한 전분의 추출수율과 이화학적 특성을 조사하였다. 채취시기별 고사리 뿌리의 생산성은 7월 27일 수확에서 3,783.3kg/10a로 유의하게 높은 수량을 보였다. 파쇄한 고사리 뿌리를 24시간 sodium metabisulfite 0.4% V/W 용액에 수침하여 전분을 추출한 후 24시간 간격으로 3회에 걸쳐 진탕, 침전과 세척의 과정을 거친 후 조사한 전분 추출 수율은 3월 26일 수확한 뿌리에서 7.6%로 가장 높았고 7월 27일과 9월 24일 채취한 경우에서는 전분이 검출되지 않았으며 10월 28일에는 4.9%의 유의하게 낮았다. 추출한 전분의 색도분석에서 L값은 채취시기가 늦어질수록 높아지는 경향을 보였고 a, b값은 낮아지는 경향을 보여 전분의 색도가 향상되는 경향을 보였으며, 신속점도측정기로 조사한 전분의 호화특성에서는 채취시기가 늦어질수록 전분의 최고점도는 높아졌으나 최저점도 및 최종점도는 낮아지는 경향을 나타냈다. 전분의 무기물 함량은 3월 26일과 5월 25일 채취하는 경우 Fe > Ca > Mg > K > P의 순으로 함량이 높았으나 10월 28일 채취한 경우에서는 Fe와 Ca이 감소되고 K 함량은 증가하여 Ca > Fe > Mg > K > P의 순으로 무기물 함량이 높게 나타났다.