• Korean Journal of Food Science and Technology
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• v.30 no.5
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• pp.1006-1011
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• 1998

Volatile flavor components in three varieties (shingo(niitaka), mansamgil (okusankichi) and chuwhang pears) of Pear (Pyrus pyrifolia N.) were extracted for 24 hours with pentane-diethylether (1 : 1, v/v) using the LLEP (liquid-liquid extraction & perforation). Neutral fraction was separated from the extract and then analyzed by GC-FID and GC/MS equipped with a fused silica capillary column (Carbowax 20M, HP). Individual components were identified by mass spectrometry and their retention indices. The totals of 52, 47 and 22 volatiles were identified in shingo, mansamgil and chuwhang pears, respectively. Ethyl acetate, propyl acetate, hexanal, 1-hexanol, ethyl butanoate, ethyl-3-hydroxy butanoate, ethyl-2-hydroxy propanoate were the main components in each samples, though there were several differeces in composition of volatile compounds. Total contents of volatile components isolated in shingo, mansamgil and chuwhang pears were 6.972, 2.776 and 2.653 mg/kg of pears.

• Korean Journal of Organic Agriculture
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• v.20 no.1
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• pp.37-48
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• 2012

This study was conducted to evaluate the effects of ground cover treatments on the nutrient contribution in a 'Niitaka' pear ($Pyrus$ $pyriforia$) orchard. Treatments included; 1) sod culture, 2) winter cover crop [ryegrass+hairy vetch], and 3) winter [ryegrass+hairy vetch]+summer [greensolgo (sudan grass ($Sorghum$ $bicolor$ L.))+ nemajanghwang (crotalaria ($Crotalaria$ $juncea$ L.)] cover crops. Ryegrass and hairyvetch were seeded with 6.4 kg/10a and 3.0 kg/10a, respectively, on October 17 of 2008, and greensolgo and nemajanghwang were seeded with 2.0 kg/10a and 3.0 kg/10a, respectively, on June 4 of 2009 at a diligent farmer in Boseong in Chonnam. Winter+summer cover crops provided greater amounts of dry weight, followed by winter cover crop and sod culture. The difference of amounts of dry weight from the ground covers affected to the levels of total N, P, and K contents, which were greater nutrient levels than those of recommended nutrient requirement for satisfying 10- to 12-year-old pear tree growth. Greater amounts of dry weight from the ground covers increased organic matter and concentrations of K and Mg in soil. Foliar nutrient concentrations, as an indicator of nutrient status of a tree, were not affected by application of ground cover treatments.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.3
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• pp.408-413
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• 2005

Rheological properties and sensory characteristics of prickly pear jelly made from κ-carrageenan and glucomannan were examined. Prickly pear extract (PPE) fermented by Lactobacillus casei LS (isolated from soy milk curd residue) exhibited pH 3.12, 1.15% acidity (lactic acid) and 2.7 × 10/sup 9/ CFU/mL lactic acid bacteria. In the effect of concentration of fermented PPE, the jelly containing 4% fermented PPE had higher springiness and slightly lower hardness than that without fermented PPE, and was superior to color and taste. The hardness and brittleness of jellies were enhanced by the addition of 0.25% citric acid. The addition of 0.25% ascorbic acid resulted in the production of soft jelly like pudding. In the effect of concentration of κ-carrageenan, the hardness and springiness of jellies were increased by adding 0.75% κ-carrageenan, but was decreased by adding at the 0.9% level. In the overall preference of jellies including sweet and sour taste, higher score was obtained by the fortification of 0.6% and 0.75% κ-carrageenan, 0.25% citric acid and 30% fructose syrup.

• 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.

• Food Science and Preservation
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• v.21 no.4
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• pp.468-472
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• 2014

The effect of pre-storage treatments was investigated to control the occurrence of fruit skin stain in 'Niitaka' pears. The incidence of fruit skin stains was significantly reduced when the fruits were stored in paper bags with a yellow inner color, compared to when they were stored in paper bags with blue and red inner colors. Additionally, the pear fruits that were harvested seven days earlier than their optimum maturity date developed less fruit skin stains in cold storage and retained their quality. Storage in polyethylene (PE) bags did not control the occurrence of fruit skin stains as effectively as did bag-free storage or storage in calcium-coated bags. The dipping of the pear fruits in a chlorine dioxide and calcium solution was highly effective in reducing the fruit skin stains compared to when they were not dipped or when they were dipped only in distilled water. In particular, a 1,500 times diluted solution of sodium dichloroisocyannurate (NaDCC) reduced the incidence of fruit skin stains and the size of the lesions. No stain was observed on the skin of the fruit with a water content lower than 67.7% (w/v) during its storage. In conclusion, packaging pear fruits in bags with an inner calcium coat and dipping them in a chlorine dioxide, calcium, or NaDCC solution can effectively reduce their skin stains during their storage.

• Korean Journal of Organic Agriculture
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• v.22 no.3
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• pp.445-455
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• 2014

The pear sucker (Cacopsylla pyricola) is the most important insect pest in Korea. The hatching rates of overwintered adults laid eggs were observed at 10, 13, 18, and $22^{\circ}C$. The liner model was draw as Y=0.00277X+0.00146(Y=developmental rate, X=temperature) about temperature and developmental rate to eggs. The developmental threshold temperature to eggs was assumed about $-0.83^{\circ}C$. The egg hatching timing over 50% as the accumulated temperature by day maximum temperature $6^{\circ}C$ over from 1st February in 2008, 2009 and 2011 was 429.7, 417.6, and 424.3 degree $^{\circ}C$, respectively, was 3 to 7days before full blooming in pear orchard. On the other hand, the abamectin 1.8EC, lime sulfer, machine oil and 13 kinds of eco-friendly materials were not shown the control effect to the eggs. To mixed stage of pear sucker, the eco-friendly materials over 90% control value were 4 kinds such as a mixture of Azadiractin A+B, Nimbin, Salanin, Meliantriol and Vepol after twice application as 21st May and 5th June in pear growing season, in 2012.

• Korean Journal of Environmental Biology
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• v.34 no.4
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• pp.257-263
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• 2016

Objective of this study was to evaluate the carbon budget on 40 years old pear orchard at Naju. For carbon budget assessment, we measured the soil respiration, net ecosystem productivity of herbs, pear biomass and net ecosystem exchange. In 2015, pear orchard released about $25.6ton\;CO_2\;ha^{-1}$ by soil respiration. And $27.9ton\;CO_2\;ha^{-1}$ was sequestrated by biomass growth. Also about $12.6ton\;CO_2\;ha^{-1}$ was stored at pruning branches and about $5.2ton\;CO_2\;ha^{-1}$ for photosynthesis of herbs. As a result, 25.6 ton of $CO_2$ per ha is annually released to atmosphere. At the same time about 45.7 ton of $CO_2$ was sequestrated from atmosphere. When it sum up the amount of $CO_2$ release and sequestration, approximately $20.1ton\;CO_2\;ha^{-1}$ was sequestrated by pear orchard in 2015, and it showed no significant differences with net ecosystem exchanges ($17.8ton\;CO_2\;ha^{-1}\;yr^{-1}$) by eddy covariance method with the same period. Continuous research using various techniques will help the understanding of $CO_2$ dynamics in agroecosystem and it can be able to present a new methodology for assessment of carbon budget in woody crop field. Futhermore, it is expected that the this study can be used as the basic data to be recognized as a carbon sink.

• Korean Journal of Agricultural and Forest Meteorology
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• v.11 no.2
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• pp.61-71
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• 2009

Most deciduous trees in temperate zone are dormant during the winter to overcome cold and dry environment. Dormancy of deciduous fruit trees is usually separated into a period of rest by physiological conditions and a period of quiescence by unfavorable environmental conditions. Inconsistent and fewer budburst in pear orchards has been reported recently in South Korea and Japan and the insufficient chilling due to warmer winters is suspected to play a role. An accurate prediction of the flowering time under the climate change scenarios may be critical to the planning of adaptation strategy for the pear industry in the future. However, existing methods for the prediction of budburst depend on the spring temperature, neglecting potential effects of warmer winters on the rest release and subsequent budburst. We adapted a dormancy clock model which uses daily temperature data to calculate the thermal time for simulating winter phenology of deciduous trees and tested the feasibility of this model in predicting budburst and flowering of Niitaka pear, one of the favorite cultivars in Korea. In order to derive the model parameter values suitable for Niitaka, the mean time for the rest release was estimated by observing budburst of field collected twigs in a controlled environment. The thermal time (in chill-days) was calculated and accumulated by a predefined temperature range from fall harvest until the chilling requirement (maximum accumulated chill-days in a negative number) is met. The chilling requirement is then offset by anti-chill days (in positive numbers) until the accumulated chill-days become null, which is assumed to be the budburst date. Calculations were repeated with arbitrary threshold temperatures from $4^{\circ}C$ to $10^{\circ}C$ (at an interval of 0.1), and a set of threshold temperature and chilling requirement was selected when the estimated budburst date coincides with the field observation. A heating requirement (in accumulation of anti-chill days since budburst) for flowering was also determined from an experiment based on historical observations. The dormancy clock model optimized with the selected parameter values was used to predict flowering of Niitaka pear grown in Suwon for the recent 9 years. The predicted dates for full bloom were within the range of the observed dates with 1.9 days of root mean square error.

• Horticultural Science & Technology
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• v.30 no.1
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• pp.1-5
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• 2012

This study was conducted to elucidate the cause of micro-cracking in the exocarp of 'Jinmi' peach (Prunus persica). through the microscopic observation of fruit skin development in 4 varieties such as 'Jinmi', 'Kanoiwa Hakuto', 'Kawanakajima Hakuto', and 'Yumyeong'. Micro-cracking was noted in 59.1% of 'Jinmi', 30.6% of 'Kanoiwa Hakuto', 21.5% 'Kawanakajima Hakuto' and 6.4% of 'Yumyeong', respectively. The development of intercellular spaces, which increased rapidly with the fruit development, was easily observed at 69 days after full bloom. Histological studies revealed that the number of outer epiderm cell layers of 'Jinmi' was smaller than that of the other three cultivars, and thinner than the 'Kawanakajima Hakuto' and 'Yumyeong'. Moreover, 'Jinmi' exhibited smaller and flatter shapes in the sub-epidermal cell layer than those of the 'Kawanakajima Hakuto' and 'Yumyeong' at harvest season. Therefore, these results suggest that micro-cracking of 'Jinmi' fruit skin was due to poor-developed outer epidermis and well-developed intercellular spaces just under exocarp as compared with other varieties.

• Horticultural Science & Technology
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• v.32 no.1
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• pp.77-83
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• 2014

To improve the breeding efficiency of oriental pear, the inheritance of major fruit traits were analyzed using 4,035 seedlings of 15 cross combinations combined with 13 cultivars. Yearly variation of parental cultivars, broad-sense heritability of the traits, and frequency of seedlings with commercially acceptable characteristics by the mid-parent values were studied. Despite the heritabilities of traits related with pear the fruit texture were different depending on cross combination, the average narrow-sense heritability ($h^2$) for firmness, flesh hardness, flesh density and grit were over 0.6, a relatively high value. However fruit firmness showed different heritability among the cross combination and its value of cross combination between 'Niitaka' and 'Choju' was very low as 0.11. Positive correlation was not observed on fresh hardness, fresh density and grit but observed on firmness between mid-parent value and average value of offspring. Regression of offspring on firmness, fresh hardness, fresh density and grit between mid-parent value and average value of offspring were 0.778, 0.343, -0.273, 0.313, respectively. Frequency distributions of fruit texture in 15 cross combinations of pear seedling was influenced by parental characteristics. When fruit firmness was estimated as low, low ${\times}$ high and high ${\times}$ high values in parental fruits, firmness in their offspring exhibited low, medium and high, respectively. In addition, when parental grit by sensory evaluation were light ${\times}$ light and light-medium ${\times}$ medium-heavy, most of offsprings showed light and medium grit, respectively.