• Korean Journal of Food Science and Technology
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• v.34 no.2
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• pp.180-185
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• 2002

Volatile flavor components in three pear varieties (Pyrus pyriforia N.) of traditional cultivar, Bongri, Hwangsilri and Yongmokri, were collected by SDE method using the mixture of n-pentane and diethylether as an extract solvent and were identified by GC/MS. Among 97 compounds identified from all varieties, there were 72, 58 and 66 components in Bongri, Hwangsilri and Yongmokri, respectively. Ethyl acetate was the dominant constituent in all cultivars and also volatile profiles contained large quantity of ethanol and acetic acid. Butyl acetate identified as a main component in Bongri was not found in other pears, but in Hwangrilri and Yongmokri only 4 to 5 esters played important role in total volatile flavor composition. The volatile profiles of these three varieties were characterized by compounds in group of aldehydes, esters, alcohols, acids and ketones. As classified by functional group of separated and identified components, esters and alcohols in Bongri, alcohols in Hwangsilri, and esters in Yongmokri were roled as the title in composition of volatile flavor components. Although small amount, Yongmokri had the highest rate of volatile production at 6.552 mg/kg of pear while Hwangsilri produced the lowest at 4.175 mg/kg of pear.

• Korean journal of food and cookery science
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• v.26 no.3
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• pp.323-329
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• 2010

Studies on the tenderizing effect of fruits has been limited even though fig, kiwifruit, pear, and pineapple cultivated in Korea are utilized commonly during cooking for their proteolytic properties. Therefore, the characteristics of these fruits were investigated by treating beef with their crude protease extracts. The protease effects of crude protease extract from the fruits on casein and myofibrilar protein were in the following order : pineapple > kiwifruit > fig > pear. Electrophoretic analysis results found that pineapple, kiwifruit, and fig cleaved myosin heavy chain into smaller fragments. The myofibrilar fragmentation ratio of crude protease extracts was the highest for pineapple whileas the lowest for pear. Ground fruits (5% and 10%) increased amounts of soluble nitrogen and decreased shear force of beef. Pineapple was the most effective while pear was the least effective. Decrease in springiness and gumminess was observed by texture profile analysis of beef treated with fruits, especially pineapple and kiwifruit. Among the 5% treatments, pineapple and kiwifruit produced the highest tenderness. Additionally, 10% treatment was less preferable than the 5% treatment.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.11
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• pp.1682-1686
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• 2015

This study was conducted to establish an HPLC analysis method for determination of marker compounds as part of materials standardization for development of health functional food materials from pear pomace. The quantitative determination method of caffeic acid and chlorogenic acid as marker compounds of pear pomace extract (PPE) was optimized by HPLC analysis using a C18 column ($5{\times}250mm$, $5{\mu}m$) with a 0.2% elution gradient of acetic acid and methanol as the mobile phase at a flow rate of 0.8 mL/min and detection wavelength of 330 nm. The HPLC/UV method was applied successfully to the quantification of marker compounds in PPE after validation of the method with linearity, accuracy, and precision. The method showed high linearity of the calibration curve with a coefficient of correlation ($R^2$) of 0.9999, and limit of detection and limit of quantification were $1.14{\mu}g/mL$ (caffeic acid) and $1.61{\mu}g/mL$ (chlorogenic acid) as well as $4.9{\mu}g/mL$ (caffeic acid) and $4.9{\mu}g/mL$ (chlorogenic acid), respectively. Relative standard deviation values from intra- and inter-day precision were less than 3.1% (caffeic acid) and 4.0% (chlorogenic acid), respectively. Recovery rates of caffeic acid and chlorogenic acid at 12.5, 25, and $50{\mu}g/mL$ were 93.66~106.32% and 97.33~105.68%, respectively. An optimized method for extraction of caffeic acid and chlorogenic acid in PPE was established through diverse extraction conditions, and the validation indicated that the method is very useful for evaluation of marker compounds in PPE to develop a health functional food material.

• Applied Microscopy
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• v.48 no.3
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• pp.62-72
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• 2018

This study investigated the anti-obesity effect of a pear (Fructus Pyri Pyrifoliae) extract fermented by lactic-acid bacteria on obesity induced by a high-fat diet in rats. Body-weight measurement, blood analysis, and light microscope observation of adipose tissue in liver and epididymis were conducted after 8 weeks. Gene expression of leptin, adiponectin, and tumor necrosis $factor-{\alpha}$ ($TNF-{\alpha}$) in liver cells were also investigated. Compared to CON, PFA and PFB showed 8% weight reduction along with weight reduction of adipose tissue in liver and epididymis. Observing the microstructure of liver cells showed that lipid droplets were smaller in PFA and PFB than in CON. We confirmed that Fructus Pyri Pyrifoliae extract fermented by lactic-acid bacteria can affect gene expression of leptin, adiponectin, and $TNF-{\alpha}$ in liver cells, showing an obesity treatment effect. From the results above, it was observed that weight gain from increased gene expression in adipose cells as well as from the increased proportion of adipose cells caused by a high-fat diet can be statistically significantly reduced by taking Fructus Pyri Pyrifoliae extract fermented by lactic-acid bacteria. Therefore, Fructus Pyri Pyrifoliae extract fermented by lactic-acid bacteria can be effective for preventing and treating obesity by reducing weight and adipose cells.

• Korean Journal of Food Science and Technology
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• v.45 no.5
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• pp.557-564
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• 2013

We isolated and identified antioxidants from acidic and neutral ethyl acetate fractions of the peel of pear (Pyrus pyrifolia N. cv. Chuhwangbae). We isolated 4 compounds from the methanol extract, by using 3 different types of column chromatography (Sephadex LH-20, silica gel, and octadecylsilane) and preparative HPLC. We identified the isolated compounds as (S)-(+)-2-cis-abscisic acid O-${\beta}$-D-glucopyranosyl ester (compound 1), 1-[4-O-${\beta}$-D-glucopyranosyl]phenyl ethanone (picroside, compound 2), ${\beta}$-sitosterol (compound 3), and ${\beta}$-sitosteryl 3-O-${\beta}$-D-glucopyranoside (compound 4) by nuclear magnetic resonance analysis. We are the first to report the identification of compounds 1, 2, and 4 from pear.

• Korean Journal of Food Science and Technology
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• v.31 no.4
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• pp.971-976
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• 1999

Exo-polygalacturonase (EPG) from Rhizopus sp. was applied to the extraction of pectin from pear pomace because EPG produces pectin by solubilizing protopectin. The content of total galacturonic acid in water-alcohol insoluble pectin (WAIP) was determined as 34.6%. Pear pomace was solubilized by using EPG, with regarding reaction pH, temperature, time and ratio of enzyme to substrate in order to find optimum condition. While the yield by an acidic treatment was 6.2%, the maximum yield by an enzymatic treatment was 23.4% under the extraction condition of pH 7.8, $60^{\circ}C$, 36 hr and 1/10 of enzyme/substrate. At this condition, the purity and methoxyl content of enzyme-extracted pectin were, respectively, 34.7% and 0.7%, while those of acid-extracted pectin were, respectively, 71.1% and 5.0%. Meanwhile, the average molecular weight of pectin extracted by the enzymatic method was $2.5{\times}10^{3}$ while that of acid-solubilized pectin was $8.4{\times}10^{3}$.

• Korean Journal of Organic Agriculture
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• v.24 no.3
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• pp.557-570
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• 2016

Growth of 6-year old 'Niitaka' pear (Pyrus pyrifolia Nakai) trees and control of insect and disease occurrences were compared between fermented soybean extracts and rain-shelter system for two years. Foliar application of fermented soybean extracts was applied at 6 times as a pre-experiment in the open-field in 2013, with a rain-shelter system in 2014. Fermented soybean extract treatment increased foliar concentrations of approximately 0.46% T-N, 0.17% K, 0.19% Ca, and 0.06% Mg in 2013 compared to the control, with similar macro-nutrients between the control and soybean extract treatment observed in 2014. Rain-shelter system increased foliar concentrations of T-N, Ca, and Mg compared to the open-field. There were no significantly different between the control and soybean extract treatment for number of leaves per fruit, leaf dry weight, phytotoxicity, and completed shoot growth on August during the two years. Rain-shelter system increased leaf dry weight and did not affect phytotoxicity in the leaves. Fruit quality parameters were mostly similar to control and soybean extract treatment for two years, with higher fruit firmness observed for soybean extract treatment. Rain-shelter system advanced 4 days of harvest dates, and increased approximately 7.0 ton fruit yield per ha, 20 g mean fruit weight, and fruit soluble solid contents compared to open-field in 2014. Soybean extract treatment little suppressed occurrence of disease and insect on the leaves and fruits in both years. Rain-shelter system increased occurrence of Venturia nashicola on the leaves and to 63.8% of Gymnosporangium asiaticum on the fruits in 2014. Strong winds and storms in May elevated relative humidity in the rain-shelter system and caused high infection of the disease occurrence, requiring for an additional green control method. Soybean extract treatment little affected tree growth and would have initiated for a long-term study to evaluate tree physiological characteristics. Rain-shelter system improved fruit productivity and advanced harvest dates, which could have been more effective facility at a Thanks Giving Day between middle and end of September.

• Preventive Nutrition and Food Science
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• v.18 no.1
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• pp.76-79
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• 2013

We evaluated antioxidant activities of heated pear juice (HPJ) exposed to 120, 130, and $140^{\circ}C$ for 2 hr. HPJ was partitioned using n-hexane, chloroform, ethyl acetate, n-butanol, and water. The ethyl acetate fraction treated at $130^{\circ}C$ for 2 hr showed strong antioxidant activity; thus, this extract was isolated and purified using silica gel column chromatography and preparative high performance liquid chromatography. The structure of the purified compound was determined using ultraviolet and mass spectrometry, $^1H$-nucelar magnetic resonance (NMR), and $^{13}C$-NMR. Antioxidant activities of the isolated compound were evaluated and compared with ${\alpha}$-tocopherol, ascorbic acid, and butylated hydroxytoluene (BHT) using DPPH and ABTS assays. The isolated compound was identified as 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one (DDMP). The DPPH radical-scavenging activity ($IC_{50}$) of DDMP occurred in the following order: ascorbic acid ($45.3{\mu}g/mL$) > ${\alpha}$-tocopherol ($69.2{\mu}g/mL$) > DDMP ($241.6{\mu}g/mL$) > BHT ($268.0{\mu}g/mL$). Furthermore, DDMP showed strong ABTS radical-scavenging activity (569.0 mg AA eq/g).

• The Plant Pathology Journal
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• v.34 no.3
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• pp.191-198
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• 2018

Fast and accurate diagnosis is needed to eradicate and manage economically important and invasive diseases like fire blight. Loop-mediated isothermal amplification (LAMP) is known as the best on-site diagnostic, because it is fast, highly specific to a target, and less sensitive to inhibitors in samples. In this study, LAMP assay that gives more consistent results for on-site diagnosis of fire blight than the previous developed LAMP assays was developed. Primers for new LAMP assay (named as DS-LAMP) were designed from a histidine-tRNA ligase gene (EAMY_RS32025) of E. amylovora CFBP1430 genome. The DS-LAMP amplified DNA (positive detection) only from genomic DNA of E. amylovora strains, not from either E. pyrifoliae (causing black shoot blight) or from Pseudomonas syringae pv. syringae (causing shoot blight on apple trees). The detection limit of DS-LAMP was 10 cells per LAMP reaction, equivalent to $10^4$ cells per ml of the sample extract. DS-LAMP successfully diagnosed the pathogens on four fire-blight infected apple and pear orchards. In addition, it could distinguish black shoot blight from fire blight. The $B{\ddot{u}}hlmann$-LAMP, developed previously for on-site diagnosis of fire blight, did not give consistent results for specificity to E. amylovora and on-site diagnosis; it gave positive reactions to three strains of E. pyrifoliae and two strains of P. syringae pv. syringae. It also, gave positive reactions to some healthy sample extracts. DS-LAMP, developed in this study, would give more accurate on-site diagnosis of fire blight, especially in the Republic of Korea, where fire blight and black shoot blight coexist.

• Korean Journal Plant Pathology
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• v.2 no.2
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• pp.82-88
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• 1986

Five antifungal substances were isolated from the long-term storaged extract of common purslane, and identified as isobutyric, butyric, isovaleric, valerie and caproic acids belonging to short-chain fatty acids (C4­C6). Each of these fatty acids showed more or less antifungal potency against spore germination and mycelial growth of Alternaria alternata Japanese pear pathotype in vitro. Antifungal potency of each fatty acid against spore germination was greater than that against the mycelial growth. No one of these fatty acids completely inhibited the mycelial growth at concentration lower than 200 ppm, while 50 ppm of caproic acid and 200 ppm of valerie acid completely inhibited the spore germination. The results of bioassay also suggested that chain-length of the fatty acids might be related with the antifungal potency, since fatty acids with longer chain showed higher antifungal potency.