• Applied Biological Chemistry
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• v.40 no.1
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• pp.43-47
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• 1997

The weight ratio of the seed in jujube averaged to 19.1%. The chemical components of dried pitted-jujube were moisture 20.4%, protein 5.3%, fat 1.3%, ash 2.7%, fiber 4.4% and nitrogen-free extract 65.9%. Alcohol insoluble solid content of dried pitted-jujube was 17.4%, in which ammonium oxalate-soluble pectin was 3.7%, water-soluble pectin 3.0%, hydrochloric acid-soluble pectin 1.0%, and sodium hydroxide-soluble pectin 1.0%. Jujube contained sucrose, glucose and fructose as free sugar. The sugars of dried pitted-jujube was composed of sucrose 48.1%, fructose 18.7%, and glucose 11.3%. Drying experiments of pitted-jujube and unpitted-jujube were carried out. Moisture content and brix of dried pitted-jujube were reached at that of dried unpitted-jujube(11%, 78 brix in 48 hours of dry) in 11 hours of drying. And this means that dried pitted-jujube dried 4 times faster than dried unpitted-jujube. The extracts of dried pitted-jujube and dried unpitted-jujube were examinet according to the amount of water added and the extraction time. The brix of dried pitted-jujube extract for 30 min is similar to that of dried unpitted-jujube extract for 150 min. The brix of the extracts did not increase after 150 min extraction. As to the color of extract, 'L' value was higher in dried unpitted-be, while 'a' and 'b' values were higher in dried pitted-jujube.

• Food Science and Preservation
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• v.6 no.1
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• pp.61-65
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• 1999

This study was carried out to investigate change in the components according to drying methods of jujube. Raw jujube was dried with five methods such as sun-drying, hot-air drying after pretreated with sunlight, blanching, microwave treatment, respectively. The contents of soluble sugar and protein in sun-dried jujube were higher than those of other drying methods. The free sugars of dried jujube were consisted of sucrose, glucose and fructose. And the contents of free sugar was not different by drying methods. The major organic acids of dried jujube were oxalic acid, citric acid and malic acid. The contents of glutamic acid, glycine and alanine were higher than those of other amino acids, and the content of each amino acid was not different by drying methods.

• Food Science and Preservation
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• v.24 no.4
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• pp.505-509
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• 2017

Water vapor adsorption kinetics of vacuum-dried jujube powder were investigated in temperature and relative humidity ranges of 10 to $40^{\circ}C$ and 32 to 75%, respectively. Water vapor was initially adsorbed rapidly and then reached equilibrium condition slowly. Reaction rate constant for water vapor adsorption of vacuum-dried jujube powder increased with an increase in temperature. The temperature dependency of water activity followed the Clausius-Clapeyron equation. The net isosteric heat of sorption increased with an increase in water activity. Good straight lines were obtained with plotting of $1/(m-m_0)$ vs. 1/t. It was found that water vapor adsorption kinetics of vacuum-dried jujube powder was accurately described by a simple empirical model, and temperature dependency of the reaction rate constant followed the Arrhenius-type equation. The activation energy ranged from 50.90 to 56.00 kJ/mol depending on relative humidity. Arrhenius kinetic parameters ($E_a$ and $k_0$) for water vapor adsorption by vacuum-dried jujube powder showed an effect between the parameters with the isokinetic temperature of 302.51 K. The information on water vapor adsorption kinetics of vacuum-dried jujube powder can be used to establish the optimum condition for storage and processing of jujube.

• Food Science and Preservation
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• v.5 no.4
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• pp.346-349
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• 1998

This study was investigated to changes of texture, color and chemical properties in jujube fruits which dried by sun and hot air instrument. Weight and moisture contents were the lowest in jujube fruits dried by sun thin those of others. The ratio of water uptake was the highest in jujube fruits dried by hot air drying than those of others. The hardness and rate of rotting of dried jujube fruits were the highest in sun (Dying than those of others. The browning of jujube fruits dried by sun was higher than that of jujube fruits dried by other methods. Ash content was the highest in sun dried fruits than those of others, and content of vitamin C was the lowest in nm dried fruits than those of others.

• Food Science and Preservation
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• v.19 no.1
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• pp.87-94
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• 2012

This study was carried out to investigate the physicochemical characteristics of maturating and dried jujube. The moisture contents of the unripe and ripe jujube were found to be 84.66 and 66.45%, respectively, but that of the dried jujube was 31.48%. The crude-fat and crude-ash contents of the dried jujube were much higher than those of the maturing jujube. The carbohydrate contents of the unripe, ripe, and dried jujube were found to be 13.51, 27.94, and 61.70%, respectively, and the soluble-protein contents were 0.88, 1.73, and 3.71%. The reducing-sugar content of the dried jujube was 18.82%, higher than that of the ripe jujube. The sucrose contents of the unripe and ripe jujube were 10.15 and 16.66 g/100 g, respectively, and that of the dried jujube was 33.46 g/100 g. The major fatty acids that were found to compose jujube were palmitic, oleic, pamitoleic, linoleic, and linolenic acid. The myristoleic and arachidonic acid contents were higher in the dried jujube than in the ripe jujube, but the palmitoleic acid content was lower in the dried jujube than in the ripe jujube. The major minerals of jujube were found to be Ca, K, Mg, and P, and the total mineral contents of the unripe, ripe, and dried jujube in this study were 343.38, 584.94, and 331.56 mg/100 g, respectively. The polyphenol contents of the unripe, ripe, and dried jujube were 309.12, 248.80, and 23.34 mg/100 g, respectively, while the vitamin C contents were 610.04, 310.22, and 423.27 mg/100 g.

• Food Science and Preservation
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• v.17 no.1
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• pp.42-49
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• 2010

This study was developed a multi-step process of functional jungkwa preparation from jujube fruits to prepare a new processed food, and investigated on the quality of jujube jungkwa. The weight of jujube fruits notably increased during the second processing, compared with jungkwa prepared from dried jujube fruits using an osmosis drying treatment. The weight of jungkwa produced in the second processing step was less than those in the first step. The Hunter values (L, a, b) of dried jujube fruits after the first processing were less than those of control jujube fruits. The L value did not change after the second processing of jujube jungkwa, but the a and b values were markedly decreased. However, the Hunter values did not change during the third processing step. The moisture content of dried jujube fruit, and dried fruit treated by supplementary drying (DDJF) was 37.74 and 35.93%, respectively, and that of dried fruit treated by osmosis drying was 40.42%. The moisture content of dried jujube fruit after the second processing decreased by 2-10%, and by 4-10% after the third processing. The reabsorption ratio of jujube jungkwa after the second processing was 16.93%, and that of jungkwa produced from osmosis-dried fruit 24.81%. The strength and hardness of dried jujube fruit treated with supplementary drying (DDJF) were higher, at 3 and 2, respectively, compared to the values of dried jujube fruit. The rheology of jujube fruit and jungkwa did not change during the second processing. The color, glossiness, acceptability of appearance, flavor, and overall acceptability of dried jujube fruit treated by osmosis drying as the second processing step were somewhat higher than those of fruit processed by other methods. The scores for appearance, flavor, chewiness, after taste, and overall acceptability of dried fruits treated with supplementary drying as the third processing step were somewhat greater than those of fruit prepared by other means. Accordingly, we have developed a process for preparation of jungkwa from dried jujube fruit treated by supplementary drying and osmosis drying as the second and third processing steps.

• Food Science and Preservation
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• v.19 no.6
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• pp.901-908
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• 2012

This study was conducted to analyze the antioxidant activities of fermented black jujube and to compare these with those of dried jujube, for the development of functional materials. The antioxidative activities of dried jujube and fermented black jujube extracts were analyzed by electron-donating ability (EDA) using 1,1-diphenyl-2-picryl hydrazyl (DPPH), superoxide-dismutase-(SOD)-like activity by pyrogallol, nitrite-scavenging ability, and xanthin oxidase. The yield of the fermented black jujube extracts was higher than that of the dried jujube extracts, and that of the ethanol extracts was higher than that of the hot-water extracts. The total phenol contents of the hot-water extracts from fermented black jujube were higher. The EDA values of the hot-water and ethanol extracts from fermented black jujube and dried jujube increased with an increase in extract concentration, and were about 85% in a $1000{\mu}g/mL$ extract concentration. The SOD-like activity increased with an increase in extract concentration. The SOD-like activity of the hot-water extract from fermented black jujube was higher than that of the other extracts. The nitrite-scavenging ability at pH 1.2 of the hot-water extracts from dried jujube was higher than that of the other extracts. The xanthine oxidase inhibitory activities of the hot-water and ethanol extracts from fermented black jujube were higher than those of the other extracts, and increased along with the concentrations of the extracts.

• Preventive Nutrition and Food Science
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• v.18 no.1
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• pp.50-59
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• 2013

Black jujube was made by aging dried jujube and its physiochemical characteristics, antioxidant activities and ${\alpha}$-glucosidase inhibitory activities were evaluated. The moisture and sugar contents were increased depending on the period of aging times and the pH was reduced thereby increasing acidity. The color of black jujube extract was changed from red to black resulting in decreases of Hunter color values L, a and b. As the aging progressed, sucrose was decomposed by increasing glucose and fructose, indicating higher contents of the total reducing sugars. Among the six different types of organic acids extracted from dried jujube, the levels of oxalic acid and citric acid were increased as the aging progressed. The total polyphenol contents in ethanol and water extracts of dried jujube were 7.74 and 8.12 mg/g, respectively. The water extract of black jujube aged for 48 hr contained the highest polyphenol contents at 16.82 mg/g. The 5'-hydroxymethylfurfural (5'-HMF) contents of black jujube extract significantly increased by longer aging times, and contained higher contents in the ethanol extract than water extract. The ethanol extract of black jujube showed the highest 5'-HMF content with 338.89 mg% after aging for 3 days. Also, $IC_{50}$ values of black jujube aged for 72 hr evaluated by DPPH and ABTS radical assays were 0.54 and 0.59 mg/mL, respectively. ${\alpha}$-Glucosidase inhibitory activities of black jujube at the concentration of 3.33 mg/mL (ethanol extract) increased from 65 to 80 % after aging for 72 hr.

• Food Science and Preservation
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• v.20 no.1
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• pp.52-61
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• 2013

This study was conducted not only to investigate the effects of rate of addition of dried jujube to Yakju (0, 0.5, 1.0, 1.5, 2.0 percent) but also to examine the quality changes in jujube Yakju during its storage (for 75 days at $35^{\circ}C$). The results showed no significant differences in pH, total acidity, soluble solids, and anthocyanin and alcohol contents of the Yakju right after its fermentation. With the increase in the amount of jujube that was added, the lightness of the jujube Yakju changed from 93 to 94, its redness decreased, and its yellowness significantly increased. The jujube Yakju that was fermented with 1.5-percent dried jujube had high sensory evaluation (selection rate) scores for color, flavor, taste and overall acceptability. It had no significant changes in pH and total acidity during its storage after its heat treatment. Its soluble solids contents tended to decrease with its heat treatment and to increase in its storage period. With respect to its color changes during its storage, the higher the ratio of the jujube that was added, the longer the storage period was, the lightness (L) and redness (a) decreased and the yellowness (b) increased. The polyphenol contents depended on the rate of addition of the dried jujube, but were not affected by the heat treatment and storage period. The organic acids in jujube Yakju were citric acid, succinic acid, lactic acid, malic acid and acetic acid.

• Journal of the East Asian Society of Dietary Life
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• v.4 no.1
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• pp.87-94
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• 1994

The conditions of water extraction form the dried jujube (Zizyphus jujuba) were examined. The general components, taste, and effect of taste correction of jujube water extract concentrate (JWEC) were investigated. desirable condition for extraction was that 100g of dried jujube was added to 750$m\ell$ of water and heated for 80 minutes at 100$^{\circ}C$. The yield of JWEC was 50% and the manin component of it was sugar (90%). The major taste of JWEC was sweetness, and it had astringent, bitter, sour and salty tastes as incidental taste. The taste was changed to desirable taste when 15% of JWEC was added to coffee, 10% of JWEC was added to fermented soy sauce, thick soypaste mixed with red pepper, and vinegar, respectively.