• Korean Journal of Agricultural Science
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• v.37 no.2
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• pp.209-216
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• 2010

In order to understand the effects of a single or combined treatments of 1-MCP($1{\mu}L/L$) and $CO_2$(100%) on the firmness of melting type peach fruit(cv. Chunjungdo), fruit were harvested at commercial maturity and examined physiological changes including flesh firmness during 10 days of shelf-life. Firmness loss of fruit was delayed by both single and combined treatments of 1-MCP and $CO_2$. The treatment of 1-MCP was more effective than $CO_2$ treatment but no additive effective on firmness retention was found in the combined treatment. The upsurge of ethylene evolution occurred 5 days of shelf-life in air treated control but ethylene evolution gradually increased in fruit treated by 1-MCP and 1-MCP+$CO_2$. The suppression of ethylene evolution seemed stronger in $CO_2$ treatment. The respiration of fruit significantly inhibited up to 10 days except control where climacteric increase of respiration was found at 10 days of shelf-life. A molecular shift of pectic polymers(an increase of chelator soluble pectins and decrease of water soluble pectins) was induced by both 1-MCP and $CO_2$ treatments. An increase of water soluble pectins was coincident with firmness loss. The delay of firmness loss seemed to be associated with the migration of calcium to wall matrix, especially pectins, resulting in the increase of wall bound calcium. The polygalacturonase activity was significantly reduced by 1-MCP alone 1 day after treatment and increased to similar level of activity 5 days after treatment compared to other treatment except air treated control whereas pectin methylesterase activity seemed not to be affected by both 1-MCP and $CO_2$ treatments. Thus, the molecular shift of pectic polymers appeared not to be related with pectin methylesterase. Further study is required to clarify the softening mechanism associated with molecular shift of pectic polymers and the inter- or intra-cellular movement of calcium ions induced by postharvest treatments of 1-MCP and $CO_2$.

• Analytical Science and Technology
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• v.30 no.4
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• pp.205-212
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• 2017

Rice endosperm, the portion that remains after milling, is the part of the rice seed that is primarily consumed as a source of nutrients. There have been many studies on polysaccharides, such as hemicellulose, cellulose, and pectins, derived from the cell walls of various plant groups. It has been reported that the acidic polysaccharide fractions, which contain water-soluble pectins that have been shown to have pharmacological effects in vivo and in vitro, have common chemical structures that include galacturonic acid polymers, rhamnose, arabinose, and galactose. However, few studies have been conducted on the acidic polysaccharides contained in the endosperm of rice. In this study, we quantitatively compared the differences in the acidic polysaccharide contents from samples from two of the main varieties of rice consumed as staple foods, japonica and indica, using a colorimetric method. Rice samples were collected from 39 different regions in Korea, China, Thailand and Vietnam. Acidic polysaccharide fractions were obtained by precipitation of the alcohol-insoluble residue (AIR) and enzyme treatment of each sample. The total amount of carbohydrates and uronic acid in each acidic polysaccharide fraction were measured using the phenol-sulfuric acid method and the carbazole-sulfuric acid method, respectively. The differences in the total polysaccharide contents in the acidic polysaccharide fractions were not statistically significant (p = 0.07), but the uronic acid contents were significantly different between the two groups (p = 0.04).

• Korean Journal of Food Science and Technology
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• v.53 no.2
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• pp.121-125
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• 2021

Very low methoxyl pectin (VLMP) has different physical and rheological properties compared to high and low methoxyl pectins (HMP and LMP). In this study, we produced LMP and VLMP by alkaline de-esterification, and investigated the structural and textural properties. Apple peel pectin was kept at pH 12 using 5.0 M NaOH solution for 3 and 24 h to produce LMP and VLMP, respectively. The molecular weight was decreased due to the removal of an esterified group in the pectin backbones by the alkali treatment, and the VLMP showed a higher calcium ion sensitivity which leads to the production of the gel with increased hardness. The result clearly showed that VLMP has the potential to improve the texture and stability in food products depending on their degree of esterification, and this result can be applied as a functional ingredient in food industrial area application to enhance the current commercial pectins.

• Journal of the Korean Society of Food Science and Nutrition
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• v.12 no.1
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• pp.7-11
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• 1983

The purpose of this study was to prepare low methoxyl pectins (LMPs) by pectinesterase (PE) using waste tangerine peels and to compare the chemical, physical and gelling properties of the prepared pectins with the commercial LMP. The LMPs were prepared by treating albedo with 0.25M $Na_2CO_3$ to activate the PE. PE was then inactivated by heating. The sample was centrifuged and the supernatant was collected. LMP was obtained as precipitate by adding alcohol to the collected supernatant. The amounts of extractible pectins in albedo were 12.71~12.98% on a dry weight basis. Methoxyl contents of LMPs prepared by treating albedo with PE at pH 7.5 for 10min, at pH 8.5 for 10min, 20min and 30min were 5.12%, 4.27%, 3.08%, 1.85% respectively, demonstrating that the methoxyl contents of the preparations decreased as the degree of treatment albedo with PE increased. The acetyl contents of the preparations ranged from 0.09% to 0.12%, the values of which do not interfere with gel formation. The anhydrouronic acid contents of the prepared pectins were in the range of 94.2%~94.8%. The values of viscosity and molecular weights of the prepared LMPs tent to decrease as the degree of PE action on albedo increased. The textural value of the prepared LMP gels determined by Consistometer, Ridgelimeter and Instron denonstrated that the excess treatment of albedo with PE significantly impaired the gelling properties of the preparations.

• Journal of Microbiology and Biotechnology
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• v.8 no.4
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• pp.353-360
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• 1998

A bacterial strain PN33 producing large amounts of extracellular pectin lyase (PNL, EC 4.2.2.10) was isolated from soil. The isolated bacterium was identified as a strain of Bacillus sp. Production of PNL by the strain was induced only by pectins, with a higher degree of esterification, which had been added to the culture medium as a sole carbon source. The optimal medium for PNL production was determined to consist of 10 g pectin, 2 g yeast extract, 4 g $K_2HPO_4{\cdot}3H_2O$, 0.6 g $MgSO_4$, and 0.11 g $CaCl_2$ per liter (pH 7.0). The PNL activity in the culture supernatant reached the highest level of 132 mU/ml after 32 h cultivation at $37^{\circ}C$ in the optimal medium. The PNL produced was purified to homogeneity by ammonium sulfate fractionation (50~80%), and cation exchange and size exclusion chromatographies. The molecular mass of the enzyme was estimated to be approximately 52 kDa by SDS-PAGE. Almost the same mass was determined by nondenaturing PAGE, indicating that the functional enzyme had a monomeric structure. As expected, the PNL exhibited higher activities on the highly esterified pectins whereas it gave no detectable activity on polygalacturonic acid. The enzyme showed the highest activity at the acidic pH of 6.0, exceptional for a bacterial PNL. Maximum activity was measured at $40^{\circ}C$, although the stability f the purified enzyme was poor at this temperature. alcium (1 mM) was found to activate the PNL activity by $50\%$, and also remarkably increased the thermal stability f the enzyme. Phenylmethylsulfonylfluoride (PMSF) and iethylpyrocarbonate (DEPC) inhibited the PNL activity lmost completely at the concentration of 5 mM. This result ndicates that some serine and histidine residues of the nzyme may play an essential role for catalytic function of he enzyme.

• Korean Journal of Food Science and Technology
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• v.14 no.1
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• pp.63-66
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• 1982

The pectin content in tangerine peel and the characteristics of extracted pectin and its gel were determined. The pectin contents of citrus peel and citrus albedo were 11.52% and 9.3% on a dry weight basis, respectively The equivalent weight, methoxyl content and acetyl content of the extracted citrus peel pectin were 596, 13.41% and 0.125% respectively. The intrinsic viscosity and molecular weight of extracted citrus peel pectin were higher than those of commercial citrus pectin samples. The anhydrouronic acid content and jelly grade of the extracted pectins were 98.4% and 138.1, respectively. These were higher than those of commercial citrus pectin. In the textural characteristics of gels, the gel made from the extracted pectin was shown to have lower values in hardness, cohesiveness, adhesiveness and gumminess than the gels made from commercial citrus pectins.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.4
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• pp.569-573
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• 2001

A pectic substance from citron peel was extracted with different methods to establish the optimum extraction conditions. The extraction yields of pectin with HCl, citrate and tartrate (concentration : 0.1 N, extraction ratio : 1 : 20) were 17.9%, 15.6% and 11.4%, respectively. Six times of 65% ethanol washing step was followed after first ethanol precipitation of acid extract for pure pectin. The degree of esterification (DE) of pectins was in the range of 43.0~47.6% and intrinsic viscosity was in the range of 0.94~2.63 (η$_{sp}$ /C (dL/g)). The sugar compositions such as rhamnose, xylose, glucuronic acid, galacturonic acid, galactose and glucose were little different in three kinds of pectins except for the content of arabinose.

• Journal of the Korean Society of Food Science and Nutrition
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• v.25 no.4
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• pp.715-719
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• 1996

Dietary fibers consist mostly of complex carbohydrates such as cellulose, hemicelluloses and pectins, and also included are carbohydrate-based gums or hydrocolloids exampled as alginate, carrageenan, galactomannan xanthan, etc. Due to structural diversity, dietary fibers can be classified by various ways i.e., source, plant function, solubility, charge and topology. Understanding on the plant cell wall structure is of primary importance, since physicochemical properties of dietary fibers are dependent on the existence patterns in the cell wall. Depending on the four distinct observational dimensions, the physical parameters of dietary fibers were discussed in terms of raw sources, bulky & complex plant cell wall materials, individually separated hydrocolloid materials and specifically designed materials. Each existence state possesses the distinct physical parameters governing a variety of physiological properties of dietary fibers.

• Journal of Pharmaceutical Investigation
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• v.35 no.4
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• pp.243-247
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• 2005

Although many scientists have used pectin, its feasibility in terms of tablet manufacturability with a high speed machine has never been evaluated. Therefore, compactibility of different pectin types for large scale tableting operation has been evaluated. The compactibility behavior of powder pectins was studied by a compaction simulator. It was found that pectin on its own does not produce tablets of acceptable quality even at a punch velocity as low as 20 rpm (e.g. low tensile strengths, capping and lamination irrespective of applied compression force). Thus, dwell time was introduced and more hard compact was produced as relaxation time in die increases. It was concluded that frequent structural failure observed in both pectin types was due to lack of plastic deformation, poor compactibility and high elastic recovery.

• Journal of the Korean Society of Clothing and Textiles
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• v.27 no.9_10
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• pp.1144-1152
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• 2003

Kenaf has been cultivated in Jeju Island. After being harvested at 105 DAP(day after planting) and separated from kenaf stalks , decorticated kenaf basts were treated with different concentration/temperature/time combinations in order to do chemical rotting. The following fiber properties were compared; rotting effects, colors, crystallinity, molecular structures, dyeabilities, and non-cellulose contents such as pectins, lignins, & hemicellulose. The best results of chemical rotting were obtained from the specimens treated with low concentration/ low temperature/short time. Their colors were bright yellow. The lumens of specimens diminished with the affect of NaOH. The structures of chemically rotted kenaf fibers were cellulose 1. The degree of crystallinity of chemically retted kenaf fibers were very high. Non-cellulose content, especially hemicellulose, was low in the specimens treated with the high NaOH concentration. Dyeabilities of kenaf fibers were higher among the specimens without the non-cellulose content than those with the non-cellulose content.