Youngjae Shin

Optimization and Validation of High-Performance Liquid Chromatography Method for Individual Curcuminoids in Turmeric by Heat-Refluxed Extraction

Turmeric is a plant in the Zingiberaceae family which contains curcuminoids as anticancer agents and has been widely used as a main ingredient in curry powder. However, there is a lack of suitable high performance liquid chromatography-diode array detection (HPLC-DAD) methods for reducing sample preparation time and peak resolution improvement of curcuminoids (bisdemethoxycurcumin, demethoxycurcumin, and curcumin). No significant differences in yield concentrations were observed after 60 min of heat-refluxed extraction (p < 0.05). Simultaneous chromatographic separation of all three curcuminoids achieved satisfactory results with a separation factor of 1.08 and a resolution factor of 3.39 with validation results in compliance with FDA guidelines. The expanded relative measurement uncertainty results 5.71-6.60 complied with CODEX draft. The method was successfully applied to the turmeric samples (n = 107, range 2.70-4.41 g/100 g, total curcuminoids 3.58 g/100 g). These results show that heat-refluxed extraction can be carried out easily with excellent precision and accuracy of total curcuminoids in turmeric samples.

Effects of an ethylene absorbent and 1-methylcyclopropene on tomato quality and antioxidant contents during storage

We compared the effects of an ethylene absorbent and the ethylene inhibitor 1-methylcyclopropene (1-MCP) on tomato (Solanum lycopersicum Mill. cv. Dotaerang) during storage. Tomato fruits at the ‘breaker’ stage were harvested and treated with an ethylene absorbent, 1 μL·L-1 1-MCP or 2 μL·L-1 1-MCP and stored at 20°C for 15 days. We then measured weight loss, peel color, firmness, soluble solids content (SSC), titratable acidity, pH, ethylene production and total phenolic and flavonoid contents in the fruits. Color development occurred more rapidly in the control than in fruits treated with the ethylene absorbent or 1-MCP (1 μL·L-1 and 2 μL·L-1 ) on day 6 and 9. The Hunter a value (redness) of 1-MCP (2 μL·L-1 )-treated fruit on day 6 was 2.24 ± 3.8, while that of the control was 13.39 ± 2.23, indicating that color development was delayed by 1-MCP treatment (2 μL·L-1 was more effective than 1 μL·L-1 ). Ethylene absorbent treatment was not more effective at maintaining fruit firmness than 1-MCP (2 μL·L-1 ) treatment. There was no statistically significant difference in fruit firmness between the ethylene absorbent treatment group and the control. Total phenolic and total flavonoid contents increased in all treatment groups during storage. These contents did not significantly differ among groups on day 15. These results suggest that 1-MCP treatment is highly effective in delaying tomato ripening during storage and that 2 μL·L-1 1-MCP treatment is more effective than 1 μL·L-1 treatment. However, the ethylene inhibitor did not influence the levels of antioxidant compounds compared with the control.

Near-infrared reflectance spectroscopy as a rapid and non-destructive analysis tool for curcuminoids in turmeric.

INTRODUCTION Turmeric has been widely used in curry powders as the main spice. Conventional chemical analysis such as high-performance liquid chromatography (HPLC) may take several hours to extract curcuminoids and prepare samples in many turmeric processing industries. OBJECTIVE This study was conducted to evaluate curcuminoids in turmeric powder using near-infrared reflectance spectroscopy (NIRS). METHODS All spectral acquisition ranged from 1100 to 2500 nm and a chemometrics analysis using partial least-squares (PLS) regression was performed to quantify the contents of individual curcuminoids. The HPLC was carried out (n = 129) to develop a PLS model based on the reference values. RESULTS High correlation coefficient (R(2) > 0.93) and low standard error of cross-validation (SECV < 0.20 g/100 g) and standard error of prediction (SEP < 0.13 g/100 g) values were obtained for precision and accuracy. In addition, the ratio of prediction to deviation (RPD > 2.65) values was also calculated. CONCLUSION Our results indicate that NIRS could be utilised as a control procedure or as an alternative rapid and effective quantification method.

Correlation between antioxidant concentrations and activities of Yuja (Citrus junos Sieb ex Tanaka) and other citrus fruit

The antioxidant concentrations and activities of tangerines, yuja, lemons, and oranges in the Korean marketplace have been investigated. Flesh and peel tissues of the fruit were analyzed. The total vitamin C, total phenolics, flavonoid, hesperidin, and total antioxidant activity of all citrus types were higher in peel than flesh tissues. Total phenolic concentrations of flesh tissues were in the following order: lemon>yuja>tangerine>orange, while those concentrations in the peel were tangerine >yuja>orange>lemon. Lemon and yuja had higher hesperidin concentrations in flesh and peel tissues, respectively. Among the flesh samples, the total flavonoid and total phenolic concentrations were highly related with total antioxidant activity. The relationship between flavonoid and hesperidin was also strong among flesh and peel tissues. Our results indicate that citrus fruit includes high antioxidant compounds and activity and that citrus peel could be a good source of food ingredients.

Dielectric, piezoelectric and pyroelectric properties in the (1–x)Pb(Mg0.7Zn0.3)1/3Nb2/3O3-xPbTiO3 system

Abstract Dielectric, piezoelectric and pyroelectric properties of relaxor ferroelectric in the (1–x)Pb(Mg0.7Zn0.3)1/3Nb2,3O3–xPbTiO3 (PMZN-PT) solid solution series have been investigated. The diel...

A Study on the Factors Causing Analytical Errors through the Estimation of Uncertainty for Cadmium and Lead Analysis in Tomato Paste

BACKGROUND: This study aimed to estimate the mea- surement uncertainty associated with determination of cadmium and lead from tomato paste by ICP/MS. The sources of measurement uncertainty (i.e. sample weight, final volume, standard weight, purity, molecular weight, working standard solution, calibration curve, recovery and repeatability) in associated with the analysis of cadmium and lead were evaluated. METHODS AND RESULTS: The guide to the expre- ssion of uncertainty was used for the GUM (Guide to the expression of Uncertainty in Measurement) and Draft EURACHEM/CITAC (EURACHEM: A network of organization for analytical chemistry in Europe/ Co-Operation on International Traceability in Analytical Chemistry) Guide with mathematical calculation and statistical analysis. The uncertainty components were evaluated by either Type A or Type B methods and the combined standard uncertainty were calculated by statistical analysis using several factors. Expected un- certainty of cadmium and lead was 0.106±0.015 mg/kg (k=2.09) and 0.302±0.029 mg/kg (k=2.16), on basis of 95% confidence of Certified Reference Material (CRM) which was within certification range of 0.112±0.007 mg/kg for cadmium (k=2.03) and 0.316±0.021 mg/kg for lead (k=2.01), respectively. CONCLUSION(s): The most influential components in the uncertainty of heavy metals analysis were confirmed as recovery, standard calibration curve and standard solution were identified as the most influential compo- nents causing uncertainty of heavy metal analysis. Therefore, more careful consideration is required in these steps to reduce uncertainty of heavy metals ana- lysis in tomato paste.

Dielectric and pyroelectric properties in the Pb(Mg1/3Ta2/3)O3-PbZrO3 system

Abstract Dielectric and pyroelectric properties in the solid solution (1-x) Pb(Mg1/3Ta2/3)O3:xPbZrO3(PMT-PZ) are studied as a function of temperature. The stability of the perovskite phase was studied as a function of sintering temperature. The dielectric constant and loss of poled samples were determined. The addition of PbZrO3 affects the dielectric and pyroelectric properties of PMT system and the transition temperature is continuously shifted to higher temperature with increase of a small amount of PbZrO3. The composition with maximum dielectric constant exhibits the high pyroelectric coefficient

Dielectric, pyroelectric and piezoelectric properties in the Pb(Mg1/3Nb2/3)O3-Pb(Mg1/3Ta2/3)O3-PbTiO3 system

Abstract Dielectric, pyroelectric and piezoelectric properties of relaxor ferroelectric in the 0.4Pb(Mg1/3Nbm)O3-(0.6-x)Pb(Mg1/3Ta2/3)O3-xPbTiO3 solid solution series have been investigated. The dielectric constant and loss of poled ceramic samples were determined. The pyroelectric coefficient and the spontaneous polarization were measured by the static Byer-Roundy method as a function of temperature. The electromechanical coupling factor(kp) and piezoelectric d33 were measured by using the resonanceantiresonance method and Berlincourt d33 meter, respectively. The transition temperature is continuously shifted to higher temperature with increase of a small amount of PbTiO3. The composition with the maximum piezoelectric constant exhibits the high dielectric and pyroelectric constant

Error factors and uncertainty measurement for determinations of amino acid in beef bone extract

This study was demonstrated to estimate the measurement uncertainty of 23 multiple-component amino acids from beef bone extract by high performance liquid chromatography (HPLC). The sources of measurement uncertainty (i.e. sample weight, final volume, standard weight, purity, standard solution, calibration curve, recovery and repeatability) in associated with the analysis of amino acids were evaluated. The estimation of uncertainty obtained on the GUM (Guide to the expression of uncertainty in measurement) and EURACHEM document with mathematical calculation and statistical analysis. The content of total amino acids from beef bone extract was 36.18 g/100 g and the expanded uncertainty by multiplying coverage factor (k, 2.05~2.36) was 3.81 g/100 g at a 95% confidence level. The major contributors to the measurement uncertainty were identified in the order of recovery and repeatability (25.2%), sample pretreatment (24.5%), calibration-curve (24.0%) and weight of the reference material (10.4%). Therefore, more careful experiments are required in these steps to reduce uncertainties of amino acids analysis with a better personal proficiency improvement.