• Journal of Environmental Science International
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• v.1 no.2
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• pp.87-91
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• 1992

Leaf discs were excised from spinach leaves (Spinaia oleracea L.) and floated in phosphate buffer (pH 6.8) containing paraquat solutions (0, 0.1, 1.0, 10, 20, 50 and 100 ppm), and incubated in the growth chamber under 5, 500 lux illumination at $25^{\circ}C$ for 24 hr. Treatment with paraquat caused the formation of malondialdehyde (MDA), an indicator of lipid peroxidation in leaf discs. When 1.0, 10, 20, 50 and 100 ppm of paraquat solutions were applied to leaf discs, the contents of MDA were increased by 63, n6, 100, 140 and 150% of the level without paraquat treatment, respectively. 1.0, 10, 20, 50 and 100 ppm of paraquat treatments reduced the amounts of ascorbic acid in leaf discs by 23, 35, 38, 42 and 56% of the level without paraquat treatment respectively. Activities of superoxide dismutase (SOD) in leaf discs of 1.0, 10, 20, 50 and 100 ppm of paraquat treatments were decreased by 23, 42, 48, 61 and 70% of the level of SOD in non-treated group, respectively. The results suggest that paraquat may cause peroxidation of membrane lipid in spinach leaves as a result of paraquat-induced destruction of physiological defense against oxygen phytotoxicity.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.1 no.2
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• pp.87-91
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• 1997

Leaf discs were excised from spinach leaves (Spinacia oleracea L.) and floated in phosphate buffer (pH 6.8) containing paraquat solutions (0, 0.1, 1.0, 10, 20, 50 and 100 ppm), and incubated in the growth chamber under 5,500 lux illumination at $25^{\circ}C$ for 24 hr. Treatment with paraquat caused the formation of malondialdehyde (MDA), an indicator of lipid peroxidation in leaf discs. When 1.0, 10, 20, 50 and 100 ppm of paraquat solutions were applied to leaf discs, the contents of MDA were increased by 63, 86, 100, 140 and $150\%$ of the level without paraquat treatment respectively. 1.0, 10, 20, 50 and 100 ppm of paraquat treatments reduced the amounts of ascorbic acid in leaf discs by 23, 35, 38, 42 and $56\%$ of the level without paraquat treatment, respectively. Activities of superoxide dismutase (SOD) in leaf discs of 1.0, 10, 20, 50 and 100 ppm of paraquat treatments were decreased by 23, 42, 48, 61 and $70\%$ of the level of SOD in non-treated group, respectively. The results suggest that paraquat may cause peroxidation of membrane lipid in spinach leaves as a result of paraquat-induced destruction of physiological defense against oxygen phytotoxicity.

• Horticultural Science & Technology
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• v.35 no.1
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• pp.88-97
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• 2017

This study explored the physicochemical and nutritional changes associated with storage duration of fresh tomatoes. Fruits of the 'TY Megaton' and 'Yureka' tomato cultivars were harvested at the pink stage and stored at $12^{\circ}C$ for 20 days. During storage, firmness, weight loss, skin color (Hunter L, a, b, a / b values), soluble solids content (SSC), titratable acidity (TA), pH, antioxidant contents (lycopene, ascorbic acid, and total phenolics) and antioxidant activity were evaluated. Firmness was above the minimum marketable limit and fresh weight loss was below maximum acceptable weight loss after 3 weeks of storage, and no deleterious effect on antioxidant contents or activities were observed. Significant differences in SSC, TA, and pH were seen between varieties, but not between fruits stored for different durations. In both varieties, Hunter a values increased more than five-fold after 8 days of storage; this correlated with a more than four-fold accumulation of lycopene after two weeks of storage. The antioxidant activity of tomatoes was highest at the beginning of the storage period, likely because of the effective DPPH - reducing power of ascorbic acid and total phenolics. Antioxidant activity increased after 12 days of storage because of increasing lycopene content. Hence, this study indicates that pink - stage tomatoes may be stored at $12^{\circ}C$ for up to 3 weeks without affecting marketability or nutritional value.

• Food Science and Biotechnology
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• v.16 no.2
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• pp.187-192
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• 2007

The objectives of this study were to examine changes in the color and antioxidant compounds of paprika powder under various conditions, as well as to establish the suitable conditions for drying and storage. Paprika was dried using the following methods: freeze-drying, vacuum drying, far infrared-ray drying, and hot-air drying. Measurements of the moisture content, color pigments, and antioxidant compounds (total carotenoids, capsanthin, ascorbic acid, and total polyphenols) were completed during 120 days of storage at 4 and $30^{\circ}C$. We found that drying methods, storage temperatures, and packaging materials affected the American Spice Trade Association (ASTA) and Hunter color values, as well as the antioxidant content of paprika powder. There was a high correlation (r=0.87, p<0.01) between the ASTA color and the $a^*/b^*$ value. The loss of red color was closely related to the reduction of moisture content (r=0.81, p<0.01) during storage. Drying paprika with a low temperature in the absence of air resulted in better retention of the carotenoids and ascorbic acid. Also, as the retention of the carotenoids and ascorbic acid increased, the stability of the red pigment increased. Freeze-drying was found to be the most suitable drying method for the stability of the antioxidant compounds and red pigment.

• Food Science and Biotechnology
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• v.16 no.4
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• pp.590-593
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• 2007

The textural properties of doughs mixed with L-ascorbic acid (AA), trypsin hydrolyzed gluten peptide (THGP), and a mixture of AA-THGP were investigated using texture analyzer under the fermentation of the full formula and the freezing process. The full formula dough (FFD) required a shorter mixing time than the flour and water formula dough (FWD). The maximum resistance (Rmax) values of both the unfrozen and frozen doughs were lower for the FFD. The effects of AA and THGP additions were not significant (p<0.01) in FFD, however, they were significant in FWD. The freezing effect was significant (p<0.0001) for FFD, indicating that yeast fermented dough was much more sensitive to damage from freezing, which subsequently affected dough strength. Additions of AA (p=0.0026) and THGP (p=0.0097) had a significant effect on the extensibility (E-value) of unfrozen FWD, where THGP increased and AA decreased the E-value. However, freezing did not significantly effect the extensibilities of FWD (p=0.64) or FFD (p=0.21). The area of FFD was lower than the area of FWD for both the unfrozen and frozen doughs. However, the frozen dough mixed with THGP alone had the largest area overall. The addition of additives did not result in significantly different (p<0.01) areas under the curve, except in the frozen FFD. Freezing caused a statistically significant difference in the area of FWD (p=0.0045).

• Journal of Pharmaceutical Investigation
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• v.36 no.5
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• pp.305-308
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• 2006

Poloxamer-based hydrogel formulation for the topical delivery of ascorbic acid(AsA) was prepared and the effect of limonene on AsA skin permeation and localization was evaluated. In vitro rat skin permeation study, the AsA skin permeation of limonene-containing hydrogel was about 3 to 5 fold higher than control hydrogel. However the amount of permeated AsA was independent to the concentration of limonene. On the other hand the localized amount of AsA after 2 h increased proportion to the content of limonene. The increase in the ratio of localized AsA($Q_L$) to permeated AsA($Q_P$) was attributed to the limonene's ability of making polar pathway within stratum corneum by interacting on lipid domain of the skin and the AsA's hydration effect on the stratum corneum and effect on the protein domain of the skin.

• Bulletin of the Korean Chemical Society
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• v.26 no.9
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• pp.1403-1409
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• 2005

A sensitive and selective electrochemical method was developed for the amperometric determination of ascorbic acid (AA) at a glassy carbon electrode (GCE) modified with single-wall carbon nanotubesdihexadecyl hydrogen phosphate (SWNT-DHP) composite film. The SWNT-DHP composite film modified GCE was characterized with SEM. The SWNT-DHP composite film modified GCE exhibited excellent electrocatalytic behaviors toward the oxidation of AA. Compared with the bare GCE, the oxidation current of AA increased greatly and the oxidation peak potential of AA shifted negatively to about -0.018 V (vs. SCE) at the SWNT-DHP composite film modified GCE. The experimental parameters, which influence the oxidation current of AA, were optimized. Under the optimal conditions, the amperometric measurements were performed at a applied potential of -0.015 V and a linear response of AA was obtained in the range from 4 ${\times}$ $10^{-7}$ to 1 ${\times}$ $10^{-4}$ mol $L^{-1}$ and with a limit of detect (LOD) of 1.5 ${\times}$ $10^{-7}$ mol $L^{-1}$. The interferences study showed that the SWNT-DHP composite film modified GCE exhibited good sensitivity and excellent selectivity in the presence of high concentration uric acid and dopamine. The proposed procedure was successfully applied to detect AA in human urine samples with satisfactory results.

• Food Science and Preservation
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• v.22 no.1
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• pp.91-99
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• 2015

This study investigated the phenolic compounds of must and wine supplemented with different concentrations (0% (no added stems), 1%, 2%, 3%, and 5%) of fruit stems during winemaking using Muscat Bailey A (MBA) grapes. The red color, and total anthocyanin, total polyphenol, and tannin contents of the must and wine significantly (p<0.05) increased with increasing added amounts of grape fruit stems, while the volatile acid content decreased with increasing added amounts of grape fruit stems. Catechin (8.16~23.08 mg/L), gallic acid (2.32~3.28 mg/L), trans-resveratrol (1.38~3.27 mg/L), and ferulic acid (1.51~1.59 mg/L) were detected in the must and wine via HPLC. The bioactive substance contents increased with increasing added amounts of grape fruit stems, except for ferulic acid. The DPPH $IC_{50}$ activity was higher in the wine (12 mg/L) with 5% grape fruit stems than in ascorbic acid (67 mg/L). These results suggest that the fruit stems of MBA grapes can be used as functional materials for winemaking.

• Applied Biological Chemistry
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• v.24 no.3
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• pp.167-173
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• 1981

Crude enzyme of polyphenol oxidase was obtained from garlic. This enzyme actively oxidized triphenols such as pyrogallol and gallic acid, although it showed very weak activity on diphenols such as catechol and chlorogenic acid among the phenolic compounds tested. The optimum pH of the enzyme was 6.5 which was slightly higher than that of the garlic itself (pH 6.0). The enzyme was stable relatively at heat treatment. Sodium metabisulfite inhibited the enzyme activity at the concentration of 1mM, and KCN, L-ascorbic acid and thiourea also inhibited the enzyme action. $Mg^{++}$ activated the enzyme activity. $Cu^{++}$ activated slightly the enzyme action at low concentration (1mM), but inhibited at high concentration (10mM).

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.6
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• pp.708-712
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• 2006

The chemical properties of yellow and red onion were investigated and analyzed to provide basic data for functional food materialization and processing. The moisture and nitrogen free extract contents of yellow and red onion were 92.80%, 5.13% and 92.47%, 5.59%, respectively. Mineral components of yellow and red onion were rich in K (123.64 and 114.41 mg%), Na (34.09 and 33.57 mg%) and P (27.04 and 20.56 mg%). The major free sugar of yellow onion were glucose (744.2 mg%) and fructose (705.9 mg%). Whereas major free sugar of red onion were sucrose (692.8 mg%) and fructose (517.3 mg%). Glutamic acid, phenylalanine and aspartic acid in yellow and red onion were major amino acids. Abundant free amino acids in yellow onion were hydroxy-L-proline (27.34 mg%), L-serine (27.34 mg%) and L-arginine (26.25 mg%). Abundant free amino acids in red onion were L-glutamic acid (16.35 mg%), ammonium chloride (15.22 mg%) and L-serine (10.93 mg%). Ascorbic acid contents are higher in red onion (28.34 mg%) than in yellow onion (19.20 mg%). Quercetin and total polyphenol of yellow and red onion were 15.24 mg%, 5.70 mg% and 0.319 mg/g and 0.248 mg/g, respectively.