Young Shin Hong

Determination of volatile organic compounds, catechins, caffeine and theanine in Jukro tea at three growth stages by chromatographic and spectrometric methods.

Tea contains characteristic volatile organic compounds, polyphenols, caffeine and catechins, and is therefore among the most widely consumed beverages all over the world. In this study, fresh Jukro tea leaves collected from Damyang-gun (Jeollanam-do) at 40, 60 and 90day growth stages, were semi-fermented. The volatile organic compounds (VOCs) were extracted by simultaneous distillation-solvent extraction (SDE) and analyzed by gas chromatography/mass spectrometry (GC/MS). Catechins, caffeine and theanine were analyzed by high performance liquid chromatography (HPLC). A total of 159 VOCs were identified in the analyzed Jukro tea leaves. Comparatively, the increase in the concentrations of VOCs was high in 60day leaves. The content of catechins increased along the three growth stages, whereas caffeine, compared to 90day leaves, was higher for 40 and 60day leaves. Based on the results, the 60day leaves were found to be the most suitable and useful for making semi-fermented Jukro tea.

Determination of Volatile Flavour Profiles of Citrus spp. Fruits by SDE‐GC–MS and Enantiomeric Composition of Chiral Compounds by MDGC–MS

INTRODUCTION Citrus fruits are known to have characteristic enantiomeric key compounds biosynthesised by highly stereoselective enzymatic mechanisms. In the past, evaluation of the enantiomeric ratios of chiral compounds in fruits has been applied as an effective indicator of adulteration by the addition of synthetic compounds or natural components of different botanical origin. OBJECTIVE To analyse the volatile flavour compounds of Citrus junos Sieb. ex Tanaka (yuzu), Citrus limon BURM. f. (lemon) and Citrus aurantifolia Christm. Swingle (lime), and determine the enantiomeric ratios of their chiral compounds for discrimination and authentication of extracted oils. METHODOLOGY Volatile flavour compounds of the fruits of the three Citrus species were extracted by simultaneous distillation extraction and analysed by gas chromatography-mass spectrometry. The enantiomeric composition (ee%) of chiral camphene, sabinene, limonene and β-phellandrene was analysed by heart-cutting multidimensional gas chromatography-mass spectrometry. RESULTS Sixty-seven (C. junos), 77 (C. limon) and 110 (C. aurantifolia) volatile compounds were identified with limonene, γ-terpinene and linalool as the major compounds. Stereochemical analysis (ee%) revealed 1S,4R-(-) camphene (94.74, 98.67, 98.82), R-(+)-limonene (90.53, 92.97, 99.85) and S-(+)-β-phellandrene (98.69, 97.15, 92.13) in oil samples from all three species; R-(+)-sabinene (88.08) in C. junos; and S-(-)-sabinene (81.99, 79.74) in C. limon and C. aurantifolia, respectively. CONCLUSION The enantiomeric composition and excess ratios of the chiral compounds could be used as reliable indicators of genuineness and quality assurance of the oils derived from the Citrus fruit species. Copyright

Detection of Hydrocarbons Induced by Gamma and Electron Beam Irradiation in Ground Beef by Gas Chromatography–Mass Spectrometry

This study determined hydrocarbons induced by gamma and electron beam irradiation of ground beef. The samples were irradiated with 0, 2.5, 5, 7.5, 10, 15, and 20 kGy dosages of gamma-rays and an electron beam. The lipid contents were extracted by hexane and the induced hydrocarbons were separated and identified by gas chromatography–mass spectrometry. The analytical method was validated by characterization of detection limits, linearity, precision, and recovery; satisfactory results were obtained in all cases. The major hydrocarbons detected in irradiated ground beef samples were pentadecane and 1-tetradecene from palmitic acid, heptadecane, and 1-hexadecene from stearic acid, and 8-heptadecene and 1,7-hexadecadiene from oleic acid. The induced hydrocarbons were detected at irradiation levels above 2.5 kGy but not in the absence of irradiation. The induced hydrocarbons showed an increase with radiation dosage, but the concentration was slightly higher for gamma rays than for the electron beam. The 1-tetradecene, 8-heptadecene, and 1,7-hexadecadiene were detected as the major hydrocarbons and showed good linearity with irradiation level. It was concluded that these major hydrocarbons are suitable markers to distinguish irradiated and unirradiated ground beef.

Determination of Capsaicinoids in Red Pepper Products from South Korea by High-Performance Liquid Chromatography with Fluorescence Detection

ABSTRACT This study aimed at determining the concentrations of the major capsaicinoids, namely, capsaicin and dihydrocapsaicin, in commonly consumed red pepper products from South Korea. The capsaicinoids were extracted with 95% methanol and determined by high-performance liquid chromatography with florescence detection. The analytical method was validated by quality assurance parameters such as the linearity, limits of detection and quantification, precision, and accuracy. Satisfactory results were obtained in accordance to the specified criteria for application of analytical techniques in food. The concentration of capsaicinoids was the highest for red pepper powder (4.18–139.4 mg/100 g), followed by gochujang (0.93–23.20 mg/100 g), kimchi (0.05–1.16 mg/100 g), and sliced kimchi (0.06–0.88 mg/100 g). Comparing the capsaicinoid contents in samples from different production areas, no significant differences were found. This research concluded that the capsaicinoid content of red pepper products provided valuable information regarding the samples.

Comparative analysis of elemental compositions of selected edible wild plants

This study aimed to determine the elemental compositions of selected edible wild plant species, Hemerocallis fulva, Allium victorialis, Syneilesis palmata and Ligularia fischeri. The samples were dried, crushed, and subjected to microwave-assisted digestion. The macro and micro elements were analyzed by inductively coupled plasma-optical emission spectrometery (ICP-OES), and ICP-mass spectrometry (ICP-MS), respectively. The macro elements in the analyzed species decreased in the order K˃Ca˃P˃Mg˃S˃Fe˃Zn˃Na, and the micro elements followed the order Mn˃ Ba˃Rb˃ Cu˃ Ni˃Ga˃ Li˃Cr˃ V˃Co˃Be˃Se. The percentage ratio of calcium content for potassium in the samples was 42.9% (A. victorialis) > 42.4% (S. palmata) > 33.8% (L. fischeri) > 25.3% (H. fulva). The calcium content was 13.7, 10.9, 6.4, and 2.9 times higher than the phosphorus content in S. palmata, L. fischeri, A. victorialis, and H. fulva, respectively (p<0.05). Manganese was the most predominant among the trace minerals, and it followed the order of A. victorialis > H. fulva > L. fischeri > S. palmata. In general, these wild plants are richer in calcium as compared to other common vegetables, and hence can be considered a good source for calcium that is lacking in Korean food products.

Determination of macro, micro and trace elements in citrus fruits by inductively coupled plasma-optical emission spectrometry (ICP-OES), ICP-mass spectrometry and direct mercury analyzer: Elemental analysis of citrus fruits by ICP-MS, ICP-OES and DMA

BACKGROUND Citrus fruits are widely consumed around the world. Several elements are known to have important physiological functions in living things, whereas others are reported to have toxic effects. This study was aimed to analyze the concentration of macro, micro and trace elements in citrus fruit varieties. Samples were acid digested using a microwave system and analyzed for macro elements by inductively coupled plasma-optical emission spectrometry (ICP-OES) and for micro and trace elements by inductively coupled plasma-mass spectrometry (ICP-MS). The application of analytical techniques was analyzed by determining method validation parameters including limits of detection and quantification, linearity, precision, spiking experiments and analyzing certified reference material (NIST CRM-1570a), Spinach leaves. RESULTS The elemental levels of citrus fruits were found largely to be dependent upon the type of analyzed samples. Among nutritionally important elements, citrus fruits were good sources of potassium (95.13-270.4 mg kg-1 ), calcium (10.57-75.29 mg kg-1 ), zinc (466.5-1611 µg kg-1 ) and manganese (35.35-1902 µg kg-1 ). The concentrations of toxic elements (Pb, Cd, As, Al, Hg) were very low. CONCLUSION In general, the concentrations of analyzed elements were within the critical levels specified by the Food and Agriculture Organization/World Health Organization and Food and Nutrition Board USA. Linear discriminant analysis successfully separated the samples into clear groups with 93.9% correct classification.

Comparison of volatile flavor compounds of yuzu, kumquat, lemon and lime

This study was conducted to confirm the usefulness of essential oil components in yuzu and kumquat cultivated in Korea for comparison with those in lemon and lime. The volatile flavor compounds in citrus fruits (yuzu, kumquat, lemon and lime) were extracted for 3 h with 100 mL redistilled n-pentane/diethylether (1:1, v/v) mixture, using a simultaneous steam distillation and extraction apparatus (SDE). The volatile flavor compositions of the samples were analyzed by gas chromatography-mass spectrometry (GC-MS). The aroma compounds analyzed were 104 (3,713.02 mg/kg) in yuzu, 87 (621.71 mg/kg) in kumquat 103 (3,024.69 mg/kg) in lemon and 106 (2,209.16 mg/kg) in lime. Limonene was a major volatile flavor compound in four citrus fruits. The peak area of ​limonene was 35.03% in yuzu, 63.82% in kumquat, 40.35% in lemon, and 25.06% in lime. In addition to limonene, the major volatile flavor compounds were γ-terpinene, linalool, β-myrcene, (E)-β-farnesene, α-pinene and β-pinene in yuzu, and β-myrcene, α-pinene, (Z)-limonene oxide, (E)-limonene oxide, geranyl acetate and limonen-10-yl acetate in kumquat. Furthermore, γ-terpinene, β-pinene, β-myrcene, geranyl acetate, neryl acetate and (Z)-β-bisabolene in lemon and γ-terpinene, β-pinene, (Z)-β-bisabolene, neral, geranial and neryl acetate in lime were also detected. As a result, it was confirmed that the composition of volatile flavor compounds in four citrus fruits was different. Also, yuzu and kumquat are judged to be worthy of use alternatives for lemon and lime widely used in the fragrance industry.