• Applied Biological Chemistry
• /
• v.40 no.2
• /
• pp.123-127
• /
• 1997

To improve the quality and prolongation of chopped ginger, they were treated with NaCl, citric acid, ascorbic acid alone or combination of them at $5^{\circ}C$. The browning and stink of chopped ginger were prevented by adding 10% NaCl, $0.5{\sim}2.0%$ citric acid, but the control became severely browned and deteriorated after 1 month storage. The application of 0.5% citric acid maintained citrine color and decreased the activity of polyphenol oxidase(PPO) more significantly compared to 5.0% NaCl or 0.5% ascorbic acid. Ascorbic acid treatment become browned at $1.0{\sim}2.0%$ and easily deteriorated compared to citric acid. Citric acid(0.5%) or ascorbic acid (0.5%) treatment was largely variation of pH compared to NaCl(5.0%)+citric acid(0.5%) or NaCl(5.0%)+ascorbic acid(0.5%) treatment during 8 month storage. The activity of PPO in NaCl(5.0%)+ascorbic acid(0.5%) treatment was elevated after 4 month storage. In chopped ginger, NaCl(5.0%)+citric acid(0.5%)+ascorbic acid(0.25%) treatment was more effective than 5.0%+0.1%+0.1%, 5.0%+0.5%+0.1% during 12 month storage.

• Food Science and Preservation
• /
• v.18 no.4
• /
• pp.584-589
• /
• 2011

This study was conducted to investigate the effects of Taraxacum platycarpum and Chrysanthemum indicum extracts on the browning of apple slices. The inhibition of the PPO activities, total phenolic contents, and DPPH free-radical-scavenging activities was measured from water and from the 80% EtOH extracts of Taraxacum platycarpum and Chrysanthemum indicum as natural antibrowning agents. Apples were cut into 15-mm-thick slices, and each slice was dipped for 1 min in different treatment solutions (1% Taraxacum platycarpum and Chrysanthemum indicum extracts, 1% citric acid) and was stored at room temperature. The inhibition of the PPO activity in the Chrysanthemumin indicum extract was better than that in the Taraxacum platycarpum extract. The highest DPPH free-radical-scavenging activity (76.10%) was found in the 80% EtOH extract of Chrysanthemum indicum. After 24 h, the ${\Delta}E$ value of the apple slices that were treated in the 80% EtOH extract of Chrysanthemum indicum was at the lowest level (2.22). The total phenolic content was 94.07 mg/g, and the total flavonoid content was 102.60 mg/g, in the 80% EtOH extract of Chrysanthemum indicum. The antibrowning effect of Chrysanthemum indicum was higher than that of Taraxacum platycarpum in the apple slices.

• The Plant Pathology Journal
• /
• v.36 no.4
• /
• pp.346-354
• /
• 2020

Pectobacterium, which causes soft rot disease, is divided into 18 species based on the current classification. A total of 225 Pectobacterium strains were isolated from 10 main cultivation regions of potato (Solanum tuberosum), napa cabbage (Brassica rapa subsp. pekinensis), and radish (Raphanus sativus) in South Korea; 202 isolates (90%) were from potato, 18 from napa cabbage, and five from radish. Strains were identified using the Biolog test and phylogenetic analysis. The pathogenicity and swimming motility were tested at four different temperatures. Pectolytic activity and plant cell-wall degrading enzyme (PCWDE) activity were evaluated for six species (P. carotovorum subsp. carotovorum, Pcc; P. odoriferum, Pod; P. brasiliense, Pbr; P. versatile, Pve; P. polaris, Ppo; P. parmentieri, Ppa). Pod, Pcc, Pbr, and Pve were the most prevalent species. Although P. atrosepticum is a widespread pathogen in other countries, it was not found here. This is the first report of Ppo, Ppa, and Pve in South Korea. Pectobacterium species showed stronger activity at 28℃ and 32℃ than at 24℃, and showed weak activity at 37℃. Pectolytic activity decreased with increasing temperature. Activity of pectate lyase was not significantly affected by temperature. Activity of protease, cellulase, and polygalacturonase decreased with increasing temperature. The inability of isolated Pectobacterium to soften host tissues at 37℃ may be a consequence of decreased motility and PCWDE activity. These data suggest that future increases in temperature as a result of climate change may affect the population dynamics of Pectobacterium.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.16 no.2
• /
• pp.110-117
• /
• 1987

Polyphenol oxidase in Prunus salicina(Red) was extracted, some properties and its partially purification were investigated as follows; Polyphenol oxidase was purified about 15 folds after ammonium sulfate saturation and about 64 folds after Sephadex G-100 column chromatography. Polyphenol oxidase showed optimum pH for activity at 6.5 and optimum temperature at at $35^{\circ}C$ and high affinity to catechol in o-diphenol compounds. Thermal stability were about 85% and 75% of initial polyphenol oxidase activity remained after heating at $50^{\circ}C$ for 5 minutes and 30 minutes respectively. The Michaelis constant of the enzyme was 2.58mM. L-cysteine, glutathione, ascorbic acid and potassium cyanide appeared to be most effective inhibitors. EDTA showed a slight inhibition.

• Journal of Microbiology and Biotechnology
• /
• v.22 no.3
• /
• pp.407-415
• /
• 2012

An endophytic bacterium, Bacillus thuringiensis GS1, was isolated from bracken (Pteridium aquilinum) and found to have maximal production of chitinase (4.3 units/ml) at 5 days after culture. This study investigated the ability of B. thuringiensis GS1 to induce resistance to Rhizoctonia solani KACC 40111 (RS) in cucumber plants. Chitinase activity was greatest in RS-treated plants at 4 days. ${\beta}$-1,3-Glucanase activity was highest in GS1-treated plants at 5 days. Guaiacol peroxidase (GPOD) activity increased continuously in all treated plants for 5 days. Ascorbate peroxidase (APX) activity in RS-treated plants was increased 1.5-fold compared with the control at 4 days. Polyphenol oxidase (PPO) activity in RS-treated plants was increased 1.5-fold compared with the control at 3 days. At 5 days after treatment, activity staining revealed three bands with chitinase activity (Ch1, Ch2, and Ch3) on SDS-PAGE of cucumber plants treated with GS1+RS, whereas only one band was observed for RS-treated plants (Ch2). One GPOD isozyme (Gp1) was also observed in response to treatment with RS and GS1+RS at 4 days. One APX band (Ap2) was present on the native-PAGE gel of the control, and GS1- and GS1+RS-treated plants at 1 day. PPO bands (Po1 and Po2) from RS- and GS1+RS-treated plants were stronger than in the control and GS1-treated plants upon native-PAGE at 5 days. Taken together, these results indicate that the induction of PR proteins and defense-related enzymes by B. thuringiensis GS1 might have suppressed the damping-off caused by R. solani KACC 40111 in cucumber plants.

• Horticultural Science & Technology
• /
• v.32 no.3
• /
• pp.353-358
• /
• 2014

Hot water dipping test was conducted for chicon to restrict red discoloration of its basal part which impairs the product value during sales. Hot water dipping treatment was given to chicon for 4 min and for 8 min at $38^{\circ}C$ and for 2 min and 4 min at $42^{\circ}C$, and for 1 min and 2 min at $45^{\circ}C$, along with control (for one min at $20^{\circ}C$). The red discoloration indices of basal part of chicon during sensory evaluation on the sixth day of storage under the storage temperature at $10^{\circ}C$ was lower at $42^{\circ}C$ for 2 min, $42^{\circ}C$ for 4 min and $45^{\circ}C$ for 1 min treatments. The color change value of the basal part in chicon measured by colorimeter showed that the lowest ${\Delta}a^*$ and ${\Delta}h$ were maintained in the basal part of chicon treated at $42^{\circ}C$ for 2 min. Whereas, color changes in $42^{\circ}C$ for 2 min and $45^{\circ}C$ for 1 min treatments were significantly low as compared with that of control. The contents of total phenolic compounds which are the substances that cause red discoloration of basal part in chicon were lowest at $42^{\circ}C$ for 2 min, $42^{\circ}C$ for 4 min and $45^{\circ}C$ for 1 min treatments. The activity of phenylalanine ammonia lyase (PAL) resposible for in the synthesis of phenolic substances was the least in $42^{\circ}C$ for 2 min treatment. Whereas, PAL activity of the chicons treated a t $42^{\circ}C$ for 2 min and at $45^{\circ}C$ for 1 min were significantly lower than that of control. However, red discoloration was progressed as similar level with that of control in the basal part of chicon at $45^{\circ}C$ for 2 min. The contents of total phenolic compounds and PAL activity in this treatment were not significantly different from those in control. The polyphenol oxidase (PPO) activity which causes red discoloration of cut tissues was low in all the treatments including $42^{\circ}C$ and $45^{\circ}C$ treatment at which no inhibition effects of the red discoloration of basal part of chicon were observed. When the correlation coefficient between each investigated index was tested, most of them showed high correlation except the PPO activity and particularly and the red discoloration index and sensory evaluation ${\Delta}h$ values, and PAL activity and total phenolic compounds content were $r=0.927^{**}$, and $r=0.942^{**}$, respectively.

• Food Science and Preservation
• /
• v.4 no.1
• /
• pp.39-44
• /
• 1997

Ethylene was treated or inhibited to investigate its effect on the physiological changes related to induction of flesh browning in Fuyu persimmon fruit. The response of fruit to ethylene was so slight, that the Fuyu fruit seemed to possess a similar characteristic to non-climacteric fruit. The flesh browning was however enhanced by ethylene treatment, although any significant increment of phenolic content or PPO activity in flesh tissue was not detected. Ethylene induced not only increasing of ion leakage from fruit tissue, but the fatty acids extracted from ethylene-treated fruit tissue were also more saturated. It was suggested that ethylene be related in the changing of membrane permeablity via saturating of fatty acid in membrane lipid. That could result in increased leakage of vacuole-stored phenolic compounds, which oxidized further by PPO to cause fruit flesh to brown.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 1993.10a
• /
• pp.423-432
• /
• 1993

The changes of quality of Fresh Shiitake (Lentinus edodes) was studied in this research work by investigating the effect of low $O_2$ content and high $CO_2$ content, well known as CA Treatment in storage, on the respiration rate and PPO Activity that was the main factor in Shiitake quality decay. CA Condition was conducted in 3 research periods that combined the $O_2$content(1%, 5% and 10%) and $CO_2$ content (5%, 10%, 15% and 20%) and air treatment as the control. The lower $O_2$content was the lower respiration rte that was showed in combination the lower respiration rate that was showed in combination of 20% $CO_2$ and 1% $O_2$ (the lowest), and the control air treatment was the highest . Very low $O_2$ content, conversly, did not show a satisfying result to the product.

• Preventive Nutrition and Food Science
• /
• v.9 no.2
• /
• pp.121-125
• /
• 2004

Effects of chemical treatment with a citric acid solution or ozonated water on microbiological changes in lettuce and cabbage during storage were studied. Fresh lettuce and cabbage samples were cut into small pieces and treated by soaking in either ozonated water or a citric acid solution. After treatment, populations of total bacteria, yeast and mold, and E. coli were determined. Numbers of microorganisms increased during storage, but ozonated water and citric acid treatments retarded the increase in microbial growth. Among treatments, 1 % citric acid treatment was the most effective in terms of microbiological change and inhibition of polyphenoloxidase (PPO). For lettuce, citric acid treatment decreased the microbial growth overall by 1.5 log CFU/g and inhibited the PPO activity by 80%. These results indicate that chemical-treated lettuce and cabbage retained a better quality than those of the control during storage.

• Food Science and Preservation
• /
• v.21 no.4
• /
• pp.473-482
• /
• 2014

Changes in quality of mushroom during storage are severe problem that reduce the shelf life of harvested mushrooms. This study investigates the effect of oriental melon peel extracts on maintenance of the quality of mushrooms (Agaricus bisporus). Mushrooms were dipped in solutions (distilled water, DW; 0.1% oriental melon peel extract, OMP; 0.1% ascorbic acid, AA; and OMP+AA) for 3 minutes. After the dipped mushrooms were air-dried at room temperature, they were packaged in a polypropylene (PP) films and stored at $4^{\circ}C$ and $15^{\circ}C$. The changes in the quality of mushrooms were measured in terms of their color, gas composition, firmness, and sensory evaluation during storage at $4^{\circ}C$ and $15^{\circ}C$. The antioxidant and anti-browning activities of oriental melon peel extract were measured with respect to their total polyphenol contents, total flavonoid contents, DPPH, ABTS radical scavenging, copper chelating activity and PPO inhibition activity. The samples that were dipped in all the solutions did not show significant differences in firmness and gas exchange during their storage at $4^{\circ}C$ and $15^{\circ}C$. At both storage temperatures, the OMP solution samples showed highest L value and lowest delta E value. The sensory evaluation showed that during the storage period, the overall acceptability of mushrooms treated with the OMP and OMP+AA solutions was higher than that of the untreated mushrooms. The total polyphenol and flavonoid contents of oriental melon peel extract were $4.81mg\;GAE{\cdot}g^{-1}$ and $1.18mg\;QE{\cdot}g^{-1}$, respectively. The DPPH, ABTS radical scavenging activity, copper chelating activity and PPO inhibition activity of the oriental melon peel extract lower than ascorbic acid. All these results suggest that oriental melon peel extract can be used as a natural browning inhibitor.