• Korean Journal of Food Science and Technology
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• v.34 no.4
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• pp.583-589
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• 2002

The rheological properties of apple pectins and tomato pectins with different degrees of side branches (sample I and sample II) were investigated with wide range of shear rate by theological modeling. Among the Power law model, Cross model and Carreau model, the Carreau model was the best fitted to the experimental data. Increasing in branching of apple pectins resulted in higher zero-shear viscosity $({\eta}_0)$. But, tomato pectins that have a low degree of side branches were shown litte difference between sample I and sample II. It is concluded that side branches of pectins can result in significant difference in rheological properties. And, this is predicted by the Carreau model.

• Korean journal of food and cookery science
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• v.2 no.1
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• pp.65-70
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• 1986

Total pectin content of Korean apple varieties at optimum harvest time was deter-mined by carbazole reaction method and pectin fraction content in each variety was also determined. Properties of pectin extracted ty 2a Sodium hexa metaphesphate were compared with commercial pectin. Among apple varieties, pectin contents varied in the range of 0.26-0.48％ on fresh basis and 1.76-4. 0% on dry basis. Ball's was the highest and then high in order of Spur early blaze, Golden delicious, Fuji. , Jonathan. In each pectin fraction, soluble pectin fractions in Rall's was the lowest and in both Spur early blaze and Golden Delicious were highest but insoluble fractions in the latter were lowest. Thub the changes in poetic substances in Spur early blaze and Golden delicious seem to he occurred: during early ripening. In the analysis of properties of isolated pectin, ash, anhydrogalacturonic arid7(AUA) content and methoxyl content were different among apple varieties. Ash and methoxyl content in all isolated pectin were higher and AUA content lower than in commercial pectin. Degree of esterification (DE) in all apple varieties were above 70％.

• 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.

• The Korean Journal of Food And Nutrition
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• v.9 no.4
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• pp.413-418
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• 1996

Two methods were used to extract pectin from apple cell wall by enzyme(Hemicellulase) and by acid. Hemicellulase was used to extract high functional pectin with higher degree of polymerization. The yield of weight of pectin by hemicellulase treatment was slightly higher than that by acid treatment. The optimal condition for extraction was accomplished by providing 1.5 grams of Hemicellulase at 38$^{\circ}C$ for 24 hours. The comparison of the pectin purity and the yield of extracts by the portion of galacturonic acid between two methods showed that the purity of pectin extracted by enzymatic method was lower than that by acid treatment.

• Korean Journal of Food Science and Technology
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• v.9 no.4
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• pp.251-254
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• 1977

Pectin, hesperidin and naringin were extracted from hot air-dried peel ($60^{\circ}C$, 1 hr and air velocity 160 fpm) of citrus produced in Korea in order to see the amount of each component contained in the peel. Pectin was extracted by three different methods and the quality and contents of the pectins were determined respectively. 1. The pectin yield by the total pectic substance method was the highest (26.0% for unshiu (U) and 28.5% for natsudaidai (N) expectedly and the soluble pectic substance method the least (13.5%(U) and 15.6% (N)) The yield by method III (extraction by water at pH 1.5 followed by isopropanol precipitation) was intermediate (18.1% (U) and 20.8%(N)). Anhydrouronic acid (AUA) content was the highest (92.0% (U) and 90.3%(N)) in those by method III. The AUA contents of the other pectins were 80.0% for soluble pectin (for both U and N), 71.6% for the commercial pectin (Sunkist Groups Inc., U.S.A.), 58.0%(N) and 63.4%(U) for total pectic substance. 2. The methoxyl content of total pectic substance was the lowest (4.81%(U) and 4.88%(N)). However, there was no significant difference in methoxyl content among the rest which were found to have low levels(5.27-7.20%). 3. The pectin by method III gave the highest jelly strength. The commercial pectin, soluble pectice substance and total pectic substance were next in order. 4. The hesperidin content of unshiu was 5.07% (dry basis) and the naringin content of natsudaidai 3.03% (dry basis).

• Korean Journal of Food Science and Technology
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• v.31 no.1
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• pp.68-73
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• 1999

In order to overcome same disadvantages of acidic solubilization of pectin from apple pomace, enzymatic selective solubilization with exo-polygalacturonase was developed. According to analyses of the effects of temperature, pH and reaction time on extraction yield, the maximum yield by the enzymatic method, shown under the extraction condition of $45^{\circ}C$, pH 7 and 60 hours, was 31.0%, whereas the yield from an acidic method was 8%. Also the quality of pectin extracted by the enzymatic method was to that from acidic solubilization. The purity and methoxyl content of enzyme-extracted pectin were 80.1% and 6.36%, respectively, which were higher than 75.7% and 2.44% of acid-solubilized pectin. Viscosity average molecular weights of enzymic extracted and acid solubilized pectins were $1.50{\times}10^4\;and\;7.66{\times}10^4$, respectively.

• Korean Journal of Food Science and Technology
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• v.17 no.6
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• pp.421-425
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• 1985

The changes of pectic substances during baking at $175{\sim}180^{\circ}C$ for 30 minutes and polygalacturonase activities of three sweet potato cultivars on textural properties were investigated. The three different types of sweet potato cultivars were the dry type (Wonki), the intermediate type (Shinmi), and the moist type (Chunmi). The moisture content, alcohol insoluble solid content, composition of pectic substances and hardness were determined before and after baking. It was found that HCl-soluble pectin was significantly changed into water soluble and sodium hexametaphosphate soluble pectin by baking. The dry type, Wonki showed the lowest moisture content, but the highest alcohol insoluble solid content and hardness. Wonki, whose polygalacturonase activity was the highest, had the highest HCl-soluble pectin content after backing.

• 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 $8.4{\times}10^{3}$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.25 no.4
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• pp.659-664
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• 1996

The amount and characteristics of pectin in the albedo and flavedo layers of the citrus peels, and those of the pulp were investigated. Alcohol insoluble solid(AIS) content was the highest in albedo layer(18.1%), and the lowest in pulp(5.7%). The pulp and the albedo layer showed a potential pectin sources as containing pectins of 40.5% and 35.2% of the total polysaccharides of the pulp and the albedo layer, respectively. Total pectin contents were about 30% of the AIS and showed comparatively constant values among the byproducts. Hydrochloric acid soluble pectin contents were the hightest in the flavedo layer, 14.0%, and the lowest in the pulp, 4.4%. Over 90% of the total pectin could be extracted after 60min with 0.05N HCI at $85^{\circ}C.$ Microwave treatment reduced the extraction time significantly ; a comparable extraction yield was acquired after 10min with microwave treatment. The degree of esterification of the extracted pectin also increased with microwave treatment. Neutral sugars in the hydrolysate of the pectin were rhamnose, arabinose, galactose, glucose and xylose. No differences in molecular weight distribution of the pectin were found between the albedo and flavedo layers. Pectin of the pulp showed different molecular weight distribution from that of the peels.