• Applied Biological Chemistry
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• v.51 no.4
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• pp.342-343
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• 2008

• The Korean Journal of Food And Nutrition
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• v.12 no.5
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• pp.478-483
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• 1999

This study was conducted to investigate functional properties of 70% acetone extract in different parts of two potato varieties. 'Superior' and 'Atlantic' potato were processed by following method. Potatoes are washed, peeled, sliced and steamed before hot air drying for flesh and peel powder. Hunter's L and b values of flesh powder from blanched 'Superior' potato were higher than flesh powder from fresh 'Superior' potato. Discoloration of 'Superior' potato was inhibited by steam blanching. Contents of total polyphenol and chlorogenic acid in the 70% acetone extract of 'Superior' potato were higher than those of 'Atlantic' potato paticularly in the blanched flesh and peel. But flavonoid was not detected in flesh extract. The phenolic concentration was not decreased by the heat treatment. The nitritescavenging and electron donating ability was greatest at the tuber peel including the skin and cortex tissue 1mm beneath the skin. From the above results browning reaction and polyphenol contents in different parts of potato slices were dependent on cutivars. Peels contained more polyphenols than those from the flesh. The results indicate that potato peel extract of steam blanched plus hot air dried potato tuber showed the effectiveness as a natural nitrite scavenger and antioxidant.

• The Plant Pathology Journal
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• v.21 no.3
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• pp.283-287
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• 2005

Since the discovery of generation of $O_2^-$ in plant, many evidence for the oxidative burst (OXB) has been accumulated in various combinations of plant and pathogen or elicitor systems. $O_2^-$ generating system responsible for the OXB was coupled with oxidation of reduced nicotinamide adenine dinucleotide phosphate (NADPH) in microsomal fraction isolated from sliced aged potato tuber slices which were treated by hyphal wall components elicitor from Phytophthora infestans (HWC). We developed new assay method for quantitative measurement of oxygen radical $O_2^-$ by using electron spin resonance (ESR) analysis during elicitor­induced OXB on the surface of plant tissues. The ESR analysis using an $O_2^-$ trapper, Tiron (1,2-dihydroxy-3,5­benzenedisulfonic acid), provided a convenient assay for detecting only $O_2^-$ during elicitor-induced OXB producing various active oxygen species (AOS) on plant tissue surface. Tiron was oxidized to Tiron semiquinon radical by $O_2^-$. Quantity of the radical signal was measured by specific spectra on ESR spectroscopy. The level of $O_2^-$ was high in from surface of potato tuber tissue treated with hyphal cell wall elicitor (HWC) from Phytophthora infestans. There was no secondary OXB induction by $H_2O_2$ treatment in plant.

• Korean Journal of Food Science and Technology
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• v.5 no.3
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• pp.157-162
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• 1973

Mode of action study of irradiation was performed with potato tuber slices, $1mm{\times}1.5cm,$ aged on moist filter paper under aseptic technique. The time courses of invertase activity, nucleic acids and respiratory activity were determined, and sensitivities of these three processes to ionizing radiation were measured. None of those processes was severely inhibited by the dosage suppressing cell division. The result of $^3H-thymidine$ incorporation suggests that the reaction site of ionizing radiation might be existent during mitosis or $G_2$ period.

• Korean Journal Plant Pathology
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• v.10 no.3
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• pp.163-168
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• 1994

Erwinia rhapontici causes soft-rot disease in a number of plants such as rhubarb, onion, hyacinth and garlic. Pectate lyase (Pel) depolymerizes pectin and other polygalacturonates, which is though to play a role in bacterial invasion of plants. Pel activity was not detected in E. rhapontici cultured in a minimal salts medium containing glycerol, polygalacturonate, or citrus pectin as a carbon source. However, when sterilized potato tuber and Chinese cabbage slices were added to minimal salts polygalacturonate (0.5%) medium, E. rhapontici produced pectate lyase enzyme. Also Pel activity was consistently detected from macerated potato tubers, Chinese cabbage leaves, lettuce leaves and celery petioles tissue. Pel in the extract of macerated Chinese cabbage caused by E. rhapontici strain 1, resulted in electrolyte loss, tissue maceration and cell death of potato tuber tissue. These results indicate that E. rhapontici produces pectate lyase only in the presence of non-diffusible plant components, and that this enzyme probably contributes to its pathogenicity.

• Korean Journal of Food Science and Technology
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• v.5 no.1
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• pp.65-69
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• 1973

Effect of various dosages of gamma ray ranging from 0 to 16 krad on wound periderm formation was investigated with aging potato tuber slices $(1cm{\times}2mm)$ under aseptic condition. Cell division was gradually inhibited with increasing dosage, and completely prevented with 16 krad treatment. Solanine content was not significantly different due to dosages. Gas chromatographic separation of 2,4-dinitrophenylhydrazone precipitate from radiation-induced carbonyl compounds in potato tubers showed that formaldehyde and acetone tended to be increased only with high dosages.

• Korean Journal of Food Science and Technology
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• v.9 no.3
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• pp.220-224
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• 1977

To dry the sweet potato efficiently, the fresh sweet potato was soaked in hot water of $60{\sim}65^{\circ}C$ for $1{\sim}1.5hrs.$ and cut into 0.5cm thick slices, followed by pressing at $40kg/cm^2$. This predehydrated cake contained $43{\sim}55%$ moisture and can be dried further either by sundrying or hot air drying. Using the dried sweet potato, ethanol was produced (ethanol production; 433l/M/T) by the conventional alcohol fermentation. The extracts as a by-product ($340{\sim}450ml$ per Kg of fresh potato) contained 5% total sugar and may be used directly for alcohol fermentation without further concentration.

• Culinary science and hospitality research
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• v.13 no.2
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• pp.254-259
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• 2007

The control of enzymic browning in potato slices by the use of citrate and phosphate buffer at different pH values and concentration was investigated. Minimally processed potatoes were stored at $5^{\circ}C$ and $20^{\circ}C$ followed by dipping in distilled water, citrate buffer (pH $3.0{\sim}5.0$) and phosphate buffer (pH $5.0{\sim}7.0$). The color characteristic was measured after storage at $5^{\circ}C$ and $20^{\circ}C$ for 24 hours. Treatment effectiveness was greatly improved by reducing pH and temperature. The citrate buffer was more effective than phosphate buffer in the browning inhibitory capacity. The citrate buffer (pH 3.0) showed the most anti-browning effect in this condition and more effective inhibition of browning by increasing concentration of treatment solution. The phosphate buffer (pH 5.0) treatment showed more effectiveness than concentration of 0.5 M of citrate buffer treatment.

• The Korean Journal of Food And Nutrition
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• v.19 no.4
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• pp.358-365
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• 2006

To study simultaneous water and solute transport kinetics during soaking in concentrated solution, the influence of the concentration and molecular weight of the solute(polyethylene glycol(PEG) and NaCl) in the soaking solution and the temperature on the water loss and solute gain rates were observed by using a model vegetable tissue(potato). When potato slices$(4cm{\times}4cm{\times}0.1cm)$ soaked in 60% PEG solutions, the water loss rate of the early phase decreased with increasing of the molecular weight of PEG from 200 to 6,000, while the final water loss increased with increasing the molecular weight of PEG and it reached to 80%. The cell wall of potato tissue was permeable to NaCl and PEGs of which average molecular weight is smaller than 400 but it was not permeable to PEG 600 and larger molecules. PEG which has average molecular weight below 600 induced plasmolysis and those above 600 induced cytorrhysis. The water loss rate of potato sample soaked in smaller molecular weight PEG solution was faster than those soaked in higher molecular weight PEG solution before cytorrhysis happened. The water loss rate was reversed after cytorrhysis happened. The volume change of potato within the first 60 minutes was larger in low molecular PEG solution but the final ratio of decreasing volume was larger in high molecular PEG solutions. In PEG 200 solution, the potato tissue was slightly shrinked without shape change. However, in PEG 4,000 solution, volume of potato was reduced significantly and potato tissue was twisted.

• Korean Journal of Food Science and Technology
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• v.26 no.6
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• pp.805-813
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• 1994

Zucchini slices, sweet potato stems, taro stems, and platycodon treated with various methods such as dipping in citric acid solution, sulfite solution, or sulfur fumigation were dried by the natural sun drying method or the forced air drying method at 50, 70, 90, or $105^{\circ}C$. Mold growth of the dried vegetables and sensory quality of the dried and rehydrated vegetables were investigated. Limiting moisture contents to prevent mold growth over 3 month storage under room temperature were 15, 20, 25, and 15% for zucchini slices, sweet potato stems, taro stems, and platycodon, respectively. The chlorophyll containing vegetables dehydrated by the forced hot air showed better sensory quality than those by the natural sun. Among the pretreatments, dipping in the sulfite solution provided the best sensory quality to the dried vegetables. The sensory quality of dried platycodon was improved to a small extent by sulfur fumigation and sulfite solution treatment. The sensory quality of the dried platycodon was not found to be affected by the drying methods. All the tested vegetables dried at $105^{\circ}C$ had the worst sensory quality. Except drying temperature of $105^{\circ}C$, the lower the drying temperature, the better the sensory quality and the rehydration rates were obtained for the tested vegetables except platycodon. The sensory quality of the platycodon was little affected by the drying temperature tested in the range of $50{\sim}90^{\circ}C$.