Kwang-Geun Lee

Antioxidant property of aroma extract isolated from clove buds [Syzygium aromaticum (L.) Merr. et Perry]

Abstract Aroma extract from dried clove buds [Syzygium aromaticum (L.) Merr. et Perry] was obtained by using steam-distillation under mild conditions (55°C and 95 mm Hg). The antioxidant property of the aroma extract was evaluated in two different assays. The aroma extract isolated from clove buds inhibited the oxidation of hexanal for 30 days at a level of 50 μg/ml. Clove bud extract inhibited malonaldehyde formation from cod liver oil by 93% at the 160 μg/ml level. Twenty-two compounds were identified in the extracts of clove buds by gas chromatography and gas chromatography/mass spectrometry. The major aroma constituents of clove buds were eugenol (24.371 mg/g) and eugenyl acetate (2.354 mg/g). Eugenol, eugenyl acetate, and benzyl alcohol inhibited the oxidation of hexanal by 99, 99, and 82%, respectively, for a period of 30 days at 500 μg/ml. Eugenol, eugenyl acetate, and benzyl alcohol inhibited malonaldehyde formation from cod liver oil by 88, 79, and 63%, respectively, at 160 μg/ml. The antioxidant activity of clove bud extract and its major aroma components, eugenol and eugenyl acetate, were comparable to that of the natural antioxidant, α-tocopherol (vitamin E).

TOXICOLOGY AND ANTIOXIDANT ACTIVITIES OF NON-ENZYMATIC BROWNING REACTION PRODUCTS: REVIEW

This article summarizes toxicity and antioxidative activity of non-enzymatic browning reaction products. The subject focuses on the formation and toxicity testing of mutagenic Maillard reaction products (MPRs) formed in food model systems and in actual foods. The MRPs have also been investigated for nutritional, physiological, and biological activities. The antioxidant properties of MRPs are also reviewed in terms of protection potential against oxidative damage associated with a wide variety of diseases such as diabetes and cancer, and pathological conditions such as aging.

Environmentally friendly preparation of pectins from agricultural byproducts and their structural/rheological characterization

Apple pomace which is the main waste of fruit juice industry was utilized to extract pectins in an environmentally friendly way, which was then compared with chemically-extracted pectins. The water-based extraction with combined physical and enzymatic treatments produced pectins with 693.2 mg g(-1) galacturonic acid and 4.6% yield, which were less than those of chemically-extracted pectins. Chemically-extracted pectins exhibited lower degree of esterification (58%) than the pectin samples obtained by physical/enzymatic treatments (69%), which were also confirmed by FT-IR analysis. When subjected to steady-shear rheological conditions, both pectin solutions were shown to have shear-thinning properties. However, decreased viscosity was observed in the pectins extracted by combined physical/enzymatic methods which could be mainly attributed to the presence of more methyl esters, thus limiting polymer chain interactions. Moreover, the pectins which were extracted by combined physical/enzymatic treatments, showed less elastic properties under high shear rate conditions, compared to the chemically-extracted pectins.

Inhibition of malonaldehyde formation from blood plasma oxidation by aroma extracts and aroma components isolated from clove and eucalyptus

The inhibitory effect of aroma extracts isolated from clove buds [Syzygium aromaticum (L.) Merr. et Perry] and eucalyptus leaves (Eucalyptus polyanthemos Schauer) on malonaldehyde (MA) formation from horse blood plasma oxidized with Fentons reagent was determined by gas chromatography. Aroma chemicals such as eugenol, thymol and benzyl alcohol, identified in the aroma extracts, were examined for their inhibitory effect on the same system. Between the two aroma extracts tested, clove exhibited the most potent antioxidant activities. Extracts of eucalyptus and clove inhibited MA formation by 23 and 48%, respectively, at the level of 400 microg/ml, whereas, alpha-tocopherol and BHT inhibited MA formation by 52 and 70%, respectively, at the same level. Eugenol, thymol and benzyl alcohol inhibited MA formation by 57, 43 and 32%, respectively, at the level of 400 microg/ml.

Antioxidative activity of heterocyclic compounds formed in Maillard reaction products

Abstract Typical heterocyclic compounds substituted with various functional groups found in Maillard reaction were examined for antioxidant activity. Pyrroles exhibited the greatest antioxidant activity among all heterocyclic compounds tested. All pyrroles inhibited hexanal oxidation by almost 100% at a concentration of 50 μg/ml over 40 days. Addition of a formyl group to the pyrrole ring enhanced antioxidative activity remarkably. Pyrrole-2-carboxaldehyde inhibited hexanal oxidation by about 90% at 5 μg/ml. Unsubstituted furan exhibited the greatest antioxidant activity among furans tested. Addition of all functional groups tested to the furan decreased antioxidative activity. Antioxidant activity of thiophene was increased by the addition of methyl groups, but addition of formyl groups to thiophene decreased antioxidant activity. Thiazoles and pyrazines were ineffective antioxidants at all concentrations tested.

Effect of cooking or handling conditions on the furan levels of processed foods

The aim of this study was to investigate the possible effects of cooking or handling conditions on the concentration of furan in processed foods. The analytical method used to analyse furan levels in foods was optimized based on solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS). In baby soups, the concentration of furan decreased by up to 22% after opening a lid for 10 min. In the baby food in retort packaging, the level of furan was reduced by 15–33% after heating the foods at 50°C without a lid. Furan in rice seasonings was evaporated completely after heating the foods at 60°C. Regarding powered milk, the levels of furan were too low to be compared under various conditions. The levels of furan decreased to 58% in beverage products for babies, after storing them at 4°C for 1 day without a lid. The levels of furan in canned foods such as cereal and vegetable were reduced by zero to 52% when they were stored without stirring in a refrigerator at 4°C for 1 day. When we boiled canned fish, the furan present was almost completely evaporated. It is recommended that canned meats be heated up to 50–70°C for the reduction (26–46%) of furan levels. The levels of furan in instant and brewed coffee samples were significantly reduced after storing for 11 to 20 min at room temperature without a lid (p < 0.05).

Formation of carcinogenic 4(5)-methylimidazole in caramel model systems: a role of sulphite.

Aqueous caramel model systems consisted the D-glucose/NH(3)/sulphite were heated at 100°C for 2 h and amounts of carcinogenic 4(5)-methylimidazole (4-MI) formed were determined. The amount formed ranged from 7.0 to 155.0 ppm. A system with 0.1 M sulphite yielded the greatest amount of 4-MI, which was 54% more than that yielded from a system without sulphite. When the amount of sulphite increased over 0.1 M, the amount of 4-MI reduced. The greatest reduction was achieved with 0.2 M sulphite by 68% compared to 0 M sulphite, suggesting that sulphite plays an important role in the formation of carcinogenic 4-MI in caramel colour. Also, a system with 0.1 M sulphite yielded the most intense caramel colour but the other levels of sulphite did not change the colour intensity significantly. Sulphite contributed slightly to the level of flavour chemicals evaluated using pyrazine formation. The results suggest that sulphite addition at appropriate amount reduces 4-MI formation in caramel colour without sacrificing flavour and colour formation.

Furan in Commercially Processed Foods: Four-Year Field Monitoring and Risk Assessment Study in Korea

The aim of this study was to monitor and assess the risk associated with the presence of furan in various food products consumed in Korea. An optimized analytical method was used for the analysis of furan levels. The optimized solid-phase microextraction (SPME) fiber exposure conditions as follows for temperature, time, and amount of sample were 50°C, 20 min, and 5 g (ml), respectively. Furan was detected in all food samples tested, at levels ranging from 0.4 ng/g in canned crab to 814 ng/g in ground roasted coffee powder. The furan levels in coffee, canned fish, canned meats, sauce, soup, retort, canned vegetables, baby foods, nutritional/diet drinks, confectionary and biscuits and snacks, juice, jams, and canned fruit were (ng/g) 169, 56.1, 30.1, 21.1, 18.1, 15.6, 10.9, 10.6, 7.1, 5.4, 3.7, 3.2, and 2.9, respectively. Furan concentrations in baby food products were between 1 and 102.5 ng/g. The total exposure estimate of furan was determined to be 10.6 ng/kg/d (maximum, 20 ng/kg/d) for adults, and 17.4 ng/kg/d (maximum. 84.9 ng/kg/d) for babies. Exposure estimates found in this study are lower than those prescribed by the U.S. Food and Drug Administration (FDA).

Monitoring and risk assessment of pesticide residues in yuza fruits (Citrus junos Sieb. ex Tanaka) and yuza tea samples produced in Korea.

The objective of this study was to establish an analytical method to measure pesticides used to cultivate yuza (Citrus junos Sieb. ex Tanaka) and to analyze pesticide residue levels of yuza and yuza tea samples. Risk assessments were also performed by calculating estimated daily intake (EDI) and acceptable daily intake (ADI). An excellent linear correlation was achieved with coefficient correlation values of 0.9750-0.9999. Percent recoveries were 80.4-109.9% for most pesticides with a <6.9% relative standard deviation (RSD). The limits of quantification for the method were 0.10-0.67 μg/ml. The RSD of intra-day and inter-day variability was <15.3%. Seven pesticides in yuza (n=80) and yuza tea (n=75) were analyzed with the optimized analytical method. Acequinocyl, spirodiclofen and carbendazim were detected in yuza samples in the concentration range of 0.07-0.15 μg/g, 0.11-1.89 μg/g, and 0.03-5.15 μg /g, respectively, whereas chlorpyrifos, prothiofos, phosalone, and deltamethrin were not detected in yuza or yuza tea. The concentrations of acequinocyl, spirodiclofen and carbendazim ranged from 0.18-1.05 μg/g, 0.13-0.29 μg/g, and 0.17-2.36 μg/g, respectively, in yuza tea samples. The percent ratios of EDI to ADI for acequinocyl, spirodiclofen, and carbendazim were 24.6%, 22.7%, and 58.5%, respectively.

Multiresidue pesticide analysis in Korean ginseng by gas chromatography–triple quadrupole tandem mass spectrometry

In this study, a new analytical method was developed based on gas chromatography-triple quadrupole tandem mass spectrometry (GC-MS/MS) and used to determine 32 multiclass pesticides in ginseng products. The analytical method was validated, yielding recovery rates in the range of 55.2-108.3%, with precision values expressed as relative standard deviation (RSD) lower or equal to 12% at the spiking levels of 30, 100, and 1000 μg/kg. Correlation coefficients and LOQs (limit of quantification) were in the range 0.9801-0.9989 and 0.15-70 g/kg, respectively. With these validation data and this method, multiresidue pesticides of ginseng samples (fresh ginseng (n=118), red ginseng (n=24), dried ginseng (n=10)) were analysed. Among them, the most frequently detected pesticide was tolclofos-methyl. Tolclofos-methyl was detected in 86.4% of fresh ginseng (18.25-404.5 μg/kg), 91.7% of red ginseng (13.14-119.4 μg/kg), and 87.5% of dried ginseng (23.15-3673 μg/kg).