• Journal of Electrochemical Science and Technology
• /
• 제12권2호
• /
• pp.173-187
• /
• 2021

In the present research, a simple electrochemical sensor based on a carbon paste electrode (CPE) modified with ZnO-Zn₂SnO₄-SnO₂ and graphene (ZnO-Zn₂SnO₄-SnO₂/Gr/CPE) was developed for the direct, simultaneous and individual electrochemical measurement of Acetaminophen (AC), Caffeine (Caf) and Ascorbic acid (AA). The synthesized nano-materials were investigated using scanning electron microscopy, X-ray Diffraction, Fourier-transform infrared spectroscopy, and electrochemical impedance spectroscopy techniques. Cyclic voltammetry and differential pulse voltammetry were applied for electrochemical investigation ZnO-Zn₂SnO₄-SnO₂/Gr/CPE, and the impact of scan rate and the concentration of H⁺ on the electrode's responses were investigated. The voltammograms showed a linear relationship between the response of the electrode for individual oxidation of AA, AC and, Caf in the range of 0.021-120, 0.018-85.3, and 0.02-97.51 μM with the detection limit of 8.94, 6.66 and 7.09 nM (S/N = 3), respectively. Also, the amperometric technique was applied for the measuring of the target molecules in the range of 0.013-16, 0.008-12 and, 0.01-14 μM for AA, AC and, Caf with the detection limit of 6.28, 3.64 and 3.85 nM, respectively. Besides, the ZnO-Zn₂SnO₄-SnO₂/Gr/CPE shows an excellent selectivity, stability, repeatability, and reproducibility for the determination of AA, AC and, Caf. Finally, the proposed sensor was successfully used to show the amount of AA, AC and, Caf in urine, blood serum samples with recoveries ranging between 95.8% and 104.06%.

• 생물환경조절학회지
• /
• 제11권3호
• /
• pp.149-150
• /
• 2002

• 한국축산식품학회지
• /
• 제37권2호
• /
• pp.305-312
• /
• 2017

This study was conducted to establish the shelf-life of a milk beverage product supplemented with coffee extracts. Qualitative changes including peroxide value (PV), microorganism content, caffeine content, and sensory evaluation were measured periodically in beverages kept at 10, 20, and $30^{\circ}C$ for 8 wk. Lipid oxidation of the product was measured by peroxide value analysis, and apparent changes were observed during a 4 wk storage period. Caffeine analysis revealed that the changes in caffeine content were negligible during the storage period. Total aerobic bacteria, Escherichia coli, yeast, and mold were not detected in the products during an 8 wk storage period. Sensory evaluation revealed that after 4 wk of storage overall acceptance was less than 3 points on a 5-point scale. In this study, PV was used as an indicator of the shelf-life of the milk beverage product. PV analysis revealed that a value of 20 meq/kg was the end of the shelf-life using the Arrhenius equation and the accelerated shelf-life test (ASLT). Assuming that the beverages are kept at $4^{\circ}C$ during distribution, calculation of when the PV reached the quality limit point (20 meq/kg) was done with the equation ln(PV) = 0.3644X - 2.21834 and, using that equation, $PV=e^{0.3644X-2.21834}$ was calculated. Therefore, 14.3086 wk was determined to be the shelf-life of the milk beverage supplemented with coffee when stored at $4^{\circ}C$.

• 한국응용약물학회:학술대회논문집
• /
• 한국응용약물학회 2003년도 Annual Meeting of KSAP : International Symposium on Pharmaceutical and Biomedical Sciences on Obesity
• /
• pp.111-111
• /
• 2003

Green tea have been widely reported as functional foods because of their various bioactivities. In the present study, we used 3T3-Ll cells model of white adipocytes to clarify whether green tea and its main pharmaceutically effective compounds (EGCG, caffeine and theanine) prevent obesity. Cellular viability, glycerol-3-phosphate dehydrogenase activity, glycerol release and HSL mRNA levels were checked. Glycerol release into the medium was significantly increased by the cells treated with green tea extract. Glycerol release into the medium was significantly increased by the cells treated with green tea extract. Caffeine and theanine from green tea showed some level of lipolytic activity, and glycerol-3-phosphate dehydrogenase activity was remarkably decreased by EGCG. These results suggest that green tea has anti-obesity effect through inhibition of adipogenesis and stimulation of lipolysis. Catechins and theanine of green tea might be the factors responsible for the modulation of lipid metabolism and adipocyte differentiation.

• 한국자원식물학회지
• /
• 제31권6호
• /
• pp.704-713
• /
• 2018

Roasting has revealed coffee's potentials as a good source of bioactive compounds. This study was done to investigate the quantitative presence and activity of bioactive compounds including caffeine, chlorogenic acid (CGA), amino acids, and antioxidant capacity on Coffea arabica L. (Guatemala finca San Sebastian) and C. robusta L. (India Azad Hind). Analysis was performed on Green Bean (GB) Medium-Light (ML), Medium (ME) and Medium-Dark (MD) samples of both varieties. From the results, caffeine content was highest in ME samples of both varieties. GB samples of both varieties had high CGA content which decreased after increasing roasting time and temperature. Most amino acids in GB samples was highest, however, glutamic acid, valine, tyrosine, isoleucine, leucine and phenylalanine had highest quantitative increase in ME samples for both varieties. $IC_{50}$ of DPPH and ABTS radical scavenging activity was highest in ML samples of both varieties. $IC_{50}$ of reducing power and total phenolic content was highest in GB sample of both varieties but decreased after increasing roasting conditions. Generally Robusta had the highest quantity of bioactive compounds and antioxidant activity. From this study, the optimal roasting condition for coffee is ME above which there is a significant reduction of bioactive compounds and antioxidant activity.

• 한국축산식품학회지
• /
• 제39권6호
• /
• pp.903-917
• /
• 2019

This study aimed to extend the shelf-life of coffee-containing milk beverage by adding Theobroma cacao (cacao nibs) extract. To prepare the beverage sample containing cacao nibs extract, 0.8% cacao nibs hydrothermal extract was aseptically injected. Qualitative changes in the beverage samples, including antioxidant effect, peroxide value (POV), caffeine content, and sensory parameters were monitored regularly during storage at 10℃, 20℃, and 30℃ for 4 wk. The inclusion of cacao nibs extract produced higher antioxidant activity compared to the control. As the storage temperature increased, the POV of all samples increased. Samples with cacao nibs extract generally displayed lower POV than the control. The caffeine content of all samples tended to decrease during storage, with the decrease accentuated by higher storage temperatures. In the shelf-life prediction using the Arrhenius model, the kinetic regressions of the cacao nibs extract-added sample and control were Y_POV=1.2212X-2.1141 (r²=0.9713) and Y_POV=1.8075X-2.0189 (r²=0.9883), respectively. Finally, the predicted shelf-life of cacao nibs-added group and control to reach the quality limit (20 meq/kg POV) were approximately 18.11 and 12.18 wk, respectively. The results collectively indicate that the addition of cacao nibs extract extends the shelf-life of the coffee-containing milk beverage and heightened the antioxidant effect.

• Applied Biological Chemistry
• /
• 제22권2호
• /
• pp.97-100
• /
• 1979

다류제품(茶類製品)의 품질(品質)을 좌우(左右)하는 다엽(茶葉)의 tannin, caffeine을 지역별(地域別) 및 야생다엽(野生茶葉)과 재배다엽별(栽培茶葉別)로 5월(月), 7월(月), 9월(月)에 적채(摘采)하여 분석(分析) 비교(比較)하였고 2종(種)의 3번재배다엽(番栽培茶葉)의 향기성분(香氣成分)을 분석(分析)하여 다음과 같은 결과(結果)를 얻었다. 1. Tannin의 함량(含量)은 $10{\sim}14%$ 범위(範圍)로 타(他) 중국종(中國種)과 같은 양(量)이며 정채시기(摘采時期)가 1,2,3기(期)에 따라 점차 증가(增加)하였으며 지역간(地域間) 및 야생다엽(野生茶葉)과 재배다엽간(栽培茶葉間)의 차이(差異)는 없었다. 2. Caffeine의 함량(含量)은 $1.5{\sim}3%$의 범위(範圍)로 타(他) 중국종(中國種)과 같은 양(量)이며 지역간(地域間) 및 야생다엽(野生茶葉)과 재배다엽간(栽培茶葉間)의 차이(差異)는 없었다. 3. 향기성분(香氣成分)은 두 재배다엽간(栽培茶葉間)에 비슷한 pattern이며 32개(個)의 peak 중(中) phenol, iso-butyl aldehyde, n-butyl aldehyde, iso-valeraldehyde, n-butyl alcohol, iso-amyl alcohol, iso-valeric acid, benzaldehyde, n-valeric acid 및 linalool 의 10종(種)을 동정(同定)하였다.

• 한국식품과학회지
• /
• 제53권5호
• /
• pp.553-560
• /
• 2021

본 연구에서는 저온진공조건에서 추출 시간과 농도에 따른 녹차 열수추출조건을 최적화한 후 HP-20 column으로 caffeine을 제거한 녹차 추출물을 이용해 theanine 함유 기능성 젤리를 제조하였다. 또한, theanine 함유 젤리의 품질 특성, 제형안정성 및 항산화 효과, AChE 억제능을 조사하였다. 최적추출조건은 8% 녹차 분말을 2시간 추출하여 theanine 0.95 mg/mL, GABA 0.28 mg/mL, caffeine 1.45 mg/mL 추출액을 HP-20 column을 이용해 80% 에탄올로 카페인을 제거하였다. 3종의 겔화제와 농도별로 4종의 theanine 추출물 S1-S4(10-50%)을 제조해 품질 특성을 조사한 결과, 젤리에 theanine 추출물이 많을수록 L값과 b값이 증가하였다. 젤리의 물리적 특성을 조사한 결과, 3가지 겔화제 중 타마린드검, 잔탄검, 로거스트콩검(2:3:5=w/w/w)을 조합한 겔화제 III이 경도와 점착성이 낮고 탄력성이 높아 조직감이 가장 뛰어났다. 제형안정성 조사 시, 35%가 첨가된 S3가 이수율 25.88%과 붕괴율 1.31%로 우수한 제형안정성을 나타냈다. 또한 theanine 함유 젤리는 95℃, 30분간 가열조건에도 theanine과 GABA 성분이 파괴되지 않고 대부분 잔존하는 것을 TLC와 LC-MS 분석을 통해 확인했다. Theanine 추출물의 농도가 높을수록 DPPH radical 소거능은 증가하며, S4(50%)는 0.075 mg/mL ascorbic acid 수준과 유사한 항산화력을 나타냈다. AChE 저해 효과는 S3(35%)가 가장 높았으며 이는 donepezil 2.5 μM과 동일한 수준의 AChE 저해 활성을 나타냈다. 따라서 본 연구는 녹차 추출물에서 caffeine을 제거한 theanine 추출물로 기능성 젤리를 제조하였으며 품질 특성을 조사하였다.

• 한국식품저장유통학회지
• /
• 제23권4호
• /
• pp.576-584
• /
• 2016

Lactobacillus plantarum CK10을 활용하여 초콜릿 발효를 수행하고 발효산물의 항산화 활성 및 성분 변화를 측정하였다. 초콜릿 발효 산물의 pH는 발효 시간이 지남에 따라 감소하고 적정산도는 증가했으며, 그 증감의 폭은 발효 4시간과 24시간에서 가장 급격히 나타났다. 폴리페놀 함량은 발효 산물의 생성이 활발히 일어나고 있을 것으로 예상되는 발효 8시간에서 약간 증가하였으나 대체로 발효 전후 간 유사한 함량이 확인되었으며, 플라보노이드 함량 또한 발효 전후가 유사하게 유지되었다. 항산화 활성의 지표로 DPPH 라디칼, ABTS 라디칼, Alkyl 라디칼에 대한 소거능을 측정하였을 때, 발효가 진행되어도 초콜릿의 우수한 라디칼 소거능이 유지됨을 확인하였다. GC-MS에 의한 성분 분석을 수행하였을 때, 발효 시간이 지남에 따라 lactic acid의 성분비가 증가하는 것을 확인하였다. 더불어 HMF, xanthosine, caffeine, theobromine 등의 물질이 주요 성분으로 검출되었다. High-performance liquid-chromatography을 이용하여 정량 분석을 수행했을 때, 발효에 따른 theobromine과 caffeine의 함량 변화는 크게 관찰되지 않았다.

• 한국보건간호학회지
• /
• 제32권2호
• /
• pp.263-274
• /
• 2018

Purpose: This study examined the correlation of insomnia, sleep quality, depression, and circadian rhythm in nursing students. Methods: A total of 213 subjects completed a questionnaire consisting of their general characteristics, Insomnia Severity Index (ISI), Pittsburgh Sleep Quality Index (PSQI), Center for Epidemiologic Studies Depression (CES-D), and Composite Scale of Morningness (CSM). The collected data were analyzed by descriptive statistics, t-test, ANOVA, and Pearson's correlation coefficient using the SPSS 23.0 program. Results: The subjects' mean scores were ISI 7.18; PSQI 11.18; CES-D 16.00; and CSM 30.18. In insomnia, there were significant differences according to caffeine, perceived health status and major satisfaction. In sleep quality, there were significant differences according to perceived health status and major satisfaction. Significant differences in depression were observed according to gender, caffeine, subjective health status, major satisfaction, and circadian rhythm by drinking and exercise. A significant positive correlation was observed among ISI, PSQI, and CES-D. ISI and CES-D were negatively correlated. Conclusion: Tailored health care programs should be developed and applied to prevent and manage sleep-related and emotion-related problems in nursing students by considering the health status, major satisfaction, and gender.