• Journal of Sericultural and Entomological Science
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• v.44 no.2
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• pp.93-98
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• 2002

Effect of reducing agent sodium hydrosulfite on the natural indigo on the silk fabrics were examined to improve traditional dyeing method. K/S values of dyed fabrics was monitored with various dyeing temperature time, amount of dye and reducing agent. The dyeability of silk fabrics was improved by using reducing agent, sodium hydrosulfite; K/S value (7.20) was higher then that (1.09) of traditional method at the frist dyeing. Natural indigo dye extracted from dyed silk fabrics are composed of isomer, indigo (67.3%) and indirubin (32.5%). However, silk fabrics showed excellent anti-microbial activity regardless of the dyeing methods.

• Journal of Sericultural and Entomological Science
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• v.47 no.2
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• pp.88-92
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• 2005

In order to make pure dyestuff extract from polygonum tinctoria, we tried to traditionally-using cockle shell which the extracted water should be filtered in indigo for 8 hours and at the $40^{\circ}C$, and 4.0 pH. The 1.631g of powder dye could be produced when the 10.0 ml of aqueous ammonia was added into the solution, which had been filtered for 8 hours with the 300 g of indigo plant and the 2.51 of water. The main components of two maded -dye which has traditionally made of this and has purely made of that compared by TLC, HPLC, LC/MC techniques. Finally, the antibacterial activities and deodorization ratio of silk fabrics with natural indigo were carried out, too.

• Proceedings of the Korean Fiber Society Conference
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• 2007.11a
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• pp.427-428
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• 2007

$Ca(OH))2$ 양에 관계없이 1일(日) 추출시에는 추출 pH 6에서 인디고 함량이 높았으며, 2일(日) 추출시에는 추출 pH에 의한 인디고 함량의 차가 매우 작았다. 추출 pH에 상관없이 쪽 추출액의 저장시간이 길어질수록 인디고 함량이 낮은 분말이 얻어졌다.

• Journal of Sericultural and Entomological Science
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• v.49 no.1
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• pp.8-13
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• 2007

Natural indigo colorants were prepared by extraction of Polygonum tinctorium which was harvested just in the blooming season(in the late of July). The components were analyzed by TLC and HPLC, and its structures were analyzed by FT-IR, EI-mass. The results obtained are summarized as follows; The natural indigo powder was dissolved in DMSO and developed in eluent, $CHCI_3/CH_3CN$(8.5:1.5 v/v) by means of TLC for its quality analysis. It was segregated into indirubin as a red colour and indigo as a blue colour. In case of HPLC analysis,. FT-IR spectrum of indirubin showed a peak for NH residue between 3200 and $3300cm^{-1}$. $^1H-NMR$ spectrum for indigo displayed AA'BB' spin system caused by indole structure between 6.5 and 7.7ppm of H4, 5, 6 and 7, and -NH proton for indirubin showed an singlet between 10.88 and 11.0ppm. EI-mass spectrum of indigo and indirubin both disclosed their molecular size as 262 and it implies that these two substances are isomer.

• Food Science and Preservation
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• v.9 no.3
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• pp.327-331
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• 2002

To develop the use of natural pigment for food, anthocyanins were isolated from grape peels which were wasted much in korea, and their characteristics were as fellows. pH has a marked influences on the color of the grape peels anthocyanin solution(GPAS). At low pH the color of GPAS was more stable than high pH. With increasing pH the color gradually fades as colorless pseudobases are formed. It showed characteristic bathnochromic shift as the solution increased. Among the sugars tested, glucose showed the most protective effect on the color of GPAS to raise the color stability, while fructose showed an adverse effect. Orgarnic acid such as citric acid prevented the degradation of anthocyanin, but ascorbic acid lowered stability of color considerably. The effect of light on GPAS was found to be very deleterious. The pigment degradation can be minimized by shielding the light from the pigment solution.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2007.11a
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• pp.95-96
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• 2007

• Journal of the Korean Society of Clothing and Textiles
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• v.42 no.2
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• pp.342-359
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• 2018

This research investigated the relationship between the amount of fixed pigment and the color of silk dyed with three types of fermented indigo powder dye under different temperatures and pH, by reduction or nonreduction method. Amount of fixed pigment was analyzed using the Ultimate 3000 HPLC-DAD instrument and the color of dyed silk was measured using the X-rite spectrocolorimeter. All silk samples dyed by reduction method showed PB color. The amount of indigotin fixation was dependent on the dyeing temperature and pH regardless of the indigotin composition in the dye. Indirubin was less dependent upon the dyeing condition in the reduction dyeing and its fixation was minimum level. Dyeing conditions which can maximize the indigotin fixation were $50^{\circ}C/pH$ 11 and $70^{\circ}C/pH$ 7 conditions in reduction dyeing. Color of silk showed more redness ($a^*$) thus higher PB color when the indigotin fixation was low and indirubin fixation was relatively high. Indirubin fixation was very low with slightly better fixation by nonreduction method. More reddish color was obtained by nonreduction dyeing, and by more alkaline dyebath.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.58 no.2
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• pp.177-184
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• 2013

This study was conducted to determinate the optimum times of transplanting and harvest for enhancing the fresh leaf yield and colorant level of an indigo crop, Persicaria tinctoria H. Gross, containing the blue dye indigo. Two cultivars, Naju Local and a new cultivar, NaramBlue, were transplanted 5 times from May 30 to July 10 at an interval of 10 days, and all of experiment plots harvested on Aug. 23 in Muan, the south area of Korea. As transplanting time was delayed, fresh leaf yield were maximum at earliest transplanting (May 30) and then decreased, while Niram (blue dye extract) and indigo content of fresh leaf remained almost constant though showed a small variation. Also, two cultivars transplanted on May 23 were harvested 5 times from Jul. 20 to Sept. 20 at an interval of 15 days. As harvest time was delayed, plant height, No. of first branches, and fresh leaf yield changed increasingly, while Niram content was increased to Aug. 20 and then decreased slightly. Indigo level increased largely to Aug. 5, and then continuously decreased with more delayed harvest. These tendencies of changes in fresh leaf yield and colorant level with different transplanting and harvest times were shown similarly in both cultivars. The results indicate that early transplanting before May 30 and harvest in early August will be appropriate for improving fresh leaf yield and colorant level.

• Journal of Sericultural and Entomological Science
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• v.47 no.1
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• pp.31-35
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• 2005

This study had done to find an easily-dyeing method for novices because the dyeing method of traditional indigo has not been general to the public so that only an expert could dye the fibers. The results are as the following. When the powders after burning the shell of cockle (tegillarca granosa) were added. pH of the solution was 12.35 The k/s value of 2.49 was the highest in the dye after dipping in the solution of indigo for 1-2 days and the k/s value was 3.10 when adding 20 g/l of the starch (55% corn-starchy products in Korean market) into the solution of indigo. In addtion, the k/s value was the highest when fermenting temperature was $30^{\circ}C$ and when the powders after burning the cockle shell were 4 g/l. There were no differences between water and lye of rice straw which had used for the ferment of indigo. The components of two dye which has traditionally made of the cockle shell and which has made of calcium hydroxide were all the same.

• Korean Journal of Food Science and Technology
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• v.31 no.2
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• pp.348-355
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• 1999

Effects of pH, sugars, organic acids, metal ions, ascorbic acid and light on the stability of anthocyanin pigment extracted from purple-fleshed potato (Solanum tuberosum L.) were studied. The pH had marked influences on the color of the potato anthocyanin pigment: i.e., the lower the pH of the anthocyanin solution was, the more stable and intenser of the pigment was. It showed characteristic bathochromic shift as the pH of the solution increased. Generally, the addition of sugars into the purple-fleshed potato anthocyanin solution caused decrease in color stability of the pigment. Among the sugars tested, maltose was the most deleterious followed by sucrose, galactose, fructose and glucose. The addition of organic acids greatly increased the stability of the pigment. Malic acid was found to be the most effective in stabilizing the pigment followed by tartaric, citric and succinic acids, while malonic acid was found to be deteriorative to the stability of the pigment. Most metal ions except $Cu^{2+}$ increased stability of the pigment-especially, $Cd^{2+}\;and\;Al^{3+}$ were more effective than the others. Ascorbic acid degraded the pigment considerably, but the adverse effect was diminished by adding thiourea. Light gave an adverse effect to the stability of the purple-fleshed potato anthocyanin pigment, which could be minimized by shielding the light from the pigment.