Pearl albefaction method mediated by keratinase and combined with redox

A keratinase and pearl technology, applied in jewelry, clothing, applications, etc., can solve problems such as loss of luster of pearls, difficulty in dissolving trace elements and pigment substances, and peeling of epidermis, avoiding peeling and foaming of pearls, and easy control of bleaching process. The effect of mild reaction conditions

Active Publication Date: 2010-01-13
SOUTH CHINA SEA INST OF OCEANOLOGY - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The trace elements and pigment substances in it affect the color of pearls and reduce the value of pearls
However, due to the stable chemical structure of keratin in the outer layer, it is insoluble in water and difficult to be degraded by common proteases such as trypsin and pepsin, so it is difficult to dissolve trace elements and pigment substances
The current pearl bleaching process mainly uses hydrogen peroxide as the main bleaching agent for boiling bleaching. Its function is to dissolve keratin and produce extremely small micropores, and trace elements and pigment substances seep out from the micropores to achieve the bleaching effect. However, due to the difference in the origin of the pearl and the time of harvesting, there are differences in itself, so the time and conditions of the bleaching reaction are not easy to control, and even the microporous structure of the pearl will be destroyed, resulting in skin peeling and blistering. Instead, it tarnishes the pearl

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] Randomly select 100 original pearl beads (unperforated pearls), add 100 mL of water containing 0.6% Bacillus subtilis keratinase by mass, adjust the pH to 7.5 with a sodium carbonate-sodium bicarbonate buffer system, and keep the temperature at 45 Between ~65°C, refining was carried out for 10 hours to obtain pearls with a decontamination and moisturizing rate of 50%.

[0024] The refined pearls were wrapped in gauze and placed in a 100mL water bath for 3.5 hours, and the temperature was controlled at 65-75°C. Then, they were placed in an ultrasonic device for 1 hour, and then the pearls were soaked in acetone for 24 hours.

[0025] The treated pearls were bleached in 100 mL of 0.5% sulfur dioxide aqueous solution, the temperature was controlled at 35° C., the pH was controlled at 6.5 (adjusted by a sodium carbonate-sodium bicarbonate buffer system), and bleached for 4 hours.

[0026] The pearls treated in the previous step were placed in a 100 mL mixed aqueous solution...

Embodiment 2

[0029] Randomly select 100 original pearl beads, add 100 mL of water containing Bacillus licheniformis keratinase with a mass fraction of 1.1%, adjust the pH value to 6.5 with a sodium carbonate-sodium bicarbonate buffer system, and keep the temperature between 50 and 60 ° C. After refining for 8 hours, the decontamination and moisturizing rate of the obtained pearls was 45%.

[0030] The refined pearls were wrapped in gauze and placed in a 100mL water bath for 3 hours, and the temperature was controlled at 60-80°C, then placed in an ultrasonic device for 40 minutes, and then the pearls were soaked in acetone for 12 hours.

[0031] The treated pearls were bleached in 100 mL of low sodium sulfite solution with a mass fraction of 3%, the temperature was controlled at 40° C., the pH was controlled at 7.0 (adjusted by sodium carbonate-sodium bicarbonate buffer solution), and bleached for 2 hours.

[0032] The pearls treated in the previous step were adjusted to pH 7.0 (sodium carb...

Embodiment 3

[0035] Randomly select 100 original pearl beads, add 100 mL of water containing 1.5% kojase keratinase by mass, adjust the pH value to 7.0 with a sodium carbonate-sodium bicarbonate buffer system, and keep the temperature between 45 and 65 °C. After 12 hours of refining, the decontamination and moisturizing rate of the pearls obtained was 44%.

[0036] The refined pearls were wrapped in gauze and placed in a water bath for 5 hours, and the temperature was controlled at 60-80°C, then placed in an ultrasonic device for 50 minutes, and then the pearls were soaked in acetone for 12 hours.

[0037] The treated pearls were bleached in a sulfur dioxide solution with a mass fraction of 2%, the temperature was controlled at 35° C., the pH was controlled at 4.5 (adjusted by sodium carbonate-sodium bicarbonate buffer solution), and bleached for 2 hours.

[0038]The pearls treated in the previous step were adjusted to pH 8.0 (sodium carbonate) in a mixed aqueous solution containing 0.1% p...

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Abstract

The invention relates to a pearl bleaching method which combines keratinase mediation and oxidation reduction and is characterized in that original pearl is refined in keratinase to remove keratin impurities on the surface of the pearl, then most pigment is decomposed after the pearl is heated by water bath, processed by ultrasonic wave and dipped in acetone; and inorganic or micromolecule organic dirt is removed, then a reducer is used for bleaching alkaline amino acid in the pearl, an oxidant and poly-glycol dimethyl ether infiltrate into the pearl to oxidize and decompose macromolecule pigment impurities; finally the pearl is whitened by using fluorescent white and treated with anti-yellowing disposal by alkyl hydrazine derivatives or thiourea solution, the obtained pearl is in bright white color or jade white color and the decontamination and moisture rate of the pearl reaches more than 96 percent. The reaction condition of the pearl bleaching method is mild, the bleaching process is easy to control, the working period is short, and the pearl bleaching method is especially suitable for the bleaching of large-diameter jewelry-degree pearls.

Description

technical field [0001] The present invention relates to a method for bleaching pearls, in particular to a method for bleaching pearls combined with redox mediated by keratinase. Background technique [0002] Pearls are biomineralized substances secreted by the mantle cells of mollusks of the genus Ophiobranchidae, Nacreidae, and Pinctadas. Its main components are calcium carbonate and keratin with hexagonal aragonite crystals, as well as some trace amounts. Elements and pigment substances. The trace elements and pigment substances in it affect the color of pearls and reduce the value of pearls. However, due to the stable chemical structure of the outer layer of keratin, it is insoluble in water and difficult to be degraded by common proteases such as trypsin and pepsin, so trace elements and pigment substances are difficult to dissolve. The current pearl bleaching process mainly uses hydrogen peroxide-based bleaching agent for boiling bleaching. Its function is to dissolve...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): A44C27/00
Inventor 张偲龙丽娟尹浩肖志会李庆欣张士忠田新朋李传荣陈书勤尹团陈永福
Owner SOUTH CHINA SEA INST OF OCEANOLOGY - CHINESE ACAD OF SCI
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