A method for degumming silk with microbial fermentation of soapberry extract

Abstract

The present application relates to a kind of methods for degumming silk with microbial fermentation of sapindus distillate, Rhizopus, rice flour and deionized water are mixed in proportion to ferment for 24 hours, then yeast and the aforementioned fermentation liquor are mixed in proportion to continue fermenting for 48 hours, the supernatant is reserved for later use, mature sapindus pericarp is dried and powdered, and deionized water is mixed in proportion to prepare sapindus suspension, the fermentation liquor and suspension are mixed in proportion to ferment thoroughly, impurities are filtered by vacuum filter, the filtered fermentation liquor is heated to 90-100 DEG C, and the degumming is carried out by putting the dried cocoon pieces in proportion, the cocoon pieces are dried again after repeated boiling and washing for 5 times, the weight difference of the dried cocoon pieces before and after degumming is compared, and the degumming rate of the present application is 20-23%. The present application uses sapindus pericarp as the basis to prepare degumming liquid by microbial fermentation, which can realize efficient degumming of silk, enhance the antibacterial property of silk, does not affect the strength of silk fibroin, and ensures natural and pollution-free, and the degumming waste liquid can be recycled and reused.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for degumming silk with microbial fermentation of soapberry extract, belonging to the field of textile printing and dyeing. BACKGROUND

[0002] Silk is a natural protein fiber, which is formed by the coagulation of silk liquid secreted by the silk glands in the silkworm body. Under an optical microscope, silk is composed of single filaments, and the main component of single filaments is silk fibroin, which is protected by sericin attached to the surface of silk fibroin. The main components of silk fibroin and sericin are both proteins, but their properties are quite different because their amino acid compositions and arrangement structures are different. The silk fibroin molecule is divided into two parts, the ordered part is difficult to react with chemical reagents and water molecules due to its tight arrangement structure, and it has a certain breaking strength due to its stable structure. The unordered part, which is easy to react with chemical reagents, has a loose structure and contains more branched chemical groups, and this part makes the silk have better fluffiness, elasticity and stretching ability. Silk fibroin is the main component that enables silk to function in dyeing and weaving, and the natural silk has poor functionality, lacks luster and has a rough hand feeling, which is not conducive to dyeing and weaving, because the sericin molecules are attached to the surface of silk fibroin. By soaking the silk in hot water and adding soap or other alkaline detergents, the sericin part of the silk can be removed due to the characteristics of the sericin molecules, which have a large number of hydrophilic groups and are easy to dissolve in water. This process is called degumming.

[0003] In large-scale industrial production of silk fibers, high-concentration acid and alkaline chemicals are used in large quantities in the degumming process of raw cocoon pieces and silk fibers, and the treatment temperature is too high, which causes great damage to silk, reduces the strength of silk fibroin, and makes it difficult to meet the high-quality requirements of making high-end silk products. In addition, the traditional degumming process is time-consuming, energy-consuming, water-consuming, and produces a large amount of alkaline or acidic degumming wastewater containing sericin protein, which is difficult to recover. In addition, the discharged degumming wastewater pollutes the environment seriously, and exploring new, environmentally friendly and efficient natural degumming process has great significance for the development of high-end silk products and is conducive to the green and sustainable development of the silk industry.

[0004] Soapberry belongs to Sapindaceae, and is originally from the south of the Yangtze River basin in China, and is now widely planted in Fujian, Zhejiang and Hunan provinces. The soapberry fruit is rich in a large number of triacylsaponin and sesqui glycosides with strong surface activity and strong antibacterial properties, and is a good biological cleaning agent raw material. The soapberry surfactant has the characteristics of natural environmental protection, green non-toxicity, mild safety, easy degradation, and also has the abilities of antibacterial, anti-inflammatory, antipruritic and anti-dandruff, and has strong cleaning power.

[0005] Microbial fermentation is the key step for preparing soapberry degumming liquid, wherein yeast and rhizopus are used. Rhizopus is a single cell fungus, and its enzyme system contains abundant amylase, including liquefied and saccharified amylase which can produce lactic acid, fumaric acid, succinic acid and trace alcohol, and alcohol substance which can be used for preparing edible sweet wine medicine and saccharified feed. Saccharomycete is a single cell fungus which can survive in aerobic and anaerobic environment. Saccharomycete can grow faster in aerobic environment, and can decompose sugar into carbon dioxide and water. In anaerobic environment, saccharomycete can decompose sugar into alcohol and CO2.

[0006] At present, there is no report of using soapberry fermentation liquid for silk degumming. Through repeated experiments, a process scheme for preparing soapberry fermentation liquid by using rhizopus and saccharomycete for silk degumming is explored. SUMMARY

[0007] In view of defects of traditional silk degumming process, the application provides a method for silk degumming by using microbial fermentation soapberry extraction liquid, which can realize efficient silk degumming, does not affect the strength of silk fibroin, ensures natural pollution-free, and can recycle the degumming waste liquid.

[0008] The application adopts a method for silk degumming by using microbial fermentation soapberry extraction liquid, and the process steps are as follows:

[0009] 1) The mature soapberry is deseeded, and the pericarp is placed in an oven at a temperature of 40-50 DEG C for 36 hours for drying; the dried soapberry pericarp is powdered, and the powder is repeatedly filtered through a 70-90 mesh screen for 3 times, and the unfiltered particles are repeatedly powdered until the particles are filtered through the screen, so that soapberry pericarp powder is obtained for standby;

[0010] 2) The rhizopus, rice powder and deionized water are mixed according to a ratio of 1:50:100, and are placed in a closed container, and are placed in a water bath at a temperature of 30-35 DEG C for fermentation for 22-26 hours, so that fermentation liquid is obtained; the saccharomycete and the fermentation liquid are mixed according to a ratio of 1:150, and are continuously placed in a water bath at a temperature of 30-35 DEG C for fermentation for 46-50 hours, and then the impurities are filtered out by using fine gauze, and the supernatant is reserved for standby;

[0011] 3) The soapberry powder and deionized water are mixed according to a ratio of 1:10-15, so that soapberry suspension liquid is prepared;

[0012] 4) The supernatant prepared in step 2) and the Sapindus suspension prepared in step 3) are added in a ratio of 1:180-220, respectively, and stirred uniformly, and stored in a closed container; the mixed liquid is placed in a water bath at 30-35°C for fermentation; after sufficient fermentation for 3-5 days, the fermented liquid is obviously stratified, with sediment at the bottom and clear supernatant, and the pH of the fermented liquid is 2.9-3.5, being weakly acidic; the saponins in Sapindus are decomposed by fermentation, and there are a large amount of metabolic products produced by fermentation in the liquid;

[0013] 5) The fermented liquid obtained in step 4) is filtered for impurities by using a vacuum filter and a 100-μm cloth funnel; and the filtered liquid is filtered through a 10-μm filter membrane for standby use;

[0014] 6) The filtered fermented liquid prepared in step 5) is heated to 90-100°C and kept at a constant temperature; according to a ratio of 1:10-15 by weight, dried silk cocoon pieces and the filtered fermented liquid are added in a heatable container, kept at 90-100°C, and boiled for 60 min, and then the silk cocoon pieces are taken out and washed with flowing clean water at 40-45°C for 3-5 times;

[0015] 7) After repeated boiling and washing for 5 times according to the method of step 6), degumming is completed, and the silk cocoon pieces are taken out and repeatedly washed with flowing clean water at 40-45°C until no impurities are washed out;

[0016] 8) The silk cocoon pieces are taken out and dried in an oven at 45-50°C.

[0017] Preferably, in step 1), the Sapindus pericarp is dried and powdered, and filtered through a 80-mesh sieve for 3 times, and the unfiltered particles are repeatedly powdered until finally filtered through the sieve.

[0018] Preferably, in step 2), the fermentation time of Rhizopus, rice powder and deionized water is 24 h, and the fermentation time of the yeast for secondary fermentation is 48 h.

[0019] Preferably, in step 2), Rhizopus, rice powder and deionized water are used to prepare the fermented liquid, and the fermentation temperature is 30-35°C; and the yeast and the aforementioned fermented liquid are mixed for secondary fermentation, and the secondary fermentation temperature is 30-35°C.

[0020] Preferably, in step 3), the Sapindus powder and deionized water are prepared into a Sapindus suspension in a ratio of 1:12.

[0021] Preferably, in step 4), the ratio of the supernatant and the Sapindus powder suspension is 1:200; the fermentation temperature is 33°C; and the fermentation time is 4 days.

[0022] As preferred, in step 6), the weight ratio of the silk cocoon piece and the fermentation liquor is 1:12; the fermentation liquor temperature is 95℃; the silk is boiled in the fermentation liquor for 60 min each time; and the silk is washed with flowing water at 43℃ for 4 times.

[0023] As preferred, in step 8), the drying temperature is 48℃.

[0024] Beneficial effects: the silk degumming by using the sapindus extract fermented by microorganisms can enhance the antibacterial property of the silk, and the inhibition rate against Staphylococcus aureus and Candida albicans is 99%, and the inhibition rate against Escherichia coli is 94%; by comparing the weight difference of the dried cocoon piece before and after degumming, the degumming rate of the present application is 20% to 23%. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 Fig. 1 is a cross-sectional view of the silk cocoon piece under the scanning electron microscope at 1000 times magnification, which is the un-degummed silk cocoon piece of the present application;

[0026] Figure 2 Fig. 2 is a cross-sectional view of the silk cocoon piece under the scanning electron microscope at 1000 times magnification, which is the silk cocoon piece degummed by the sapindus fermentation extract for 0.5 h;

[0027] Figure 3 Fig. 3 is a cross-sectional view of the silk cocoon piece under the scanning electron microscope at 1000 times magnification, which is the silk cocoon piece degummed by the sapindus fermentation extract for 1 h;

[0028] Figure 4 Fig. 4 is a cross-sectional view of the silk cocoon piece under the scanning electron microscope at 1000 times magnification, which is the silk cocoon piece degummed by the sapindus fermentation extract for 1.5 h;

[0029] Figure 5 Fig. 5 is a cross-sectional view of the silk cocoon piece under the scanning electron microscope at 500 times magnification, which is the silk cocoon piece degummed by the sapindus fermentation extract for 0.5 h;

[0030] Figure 6 Fig. 6 is the antibacterial detection report of the silk degumming product by using the sapindus extract fermented by microorganisms. DETAILED DESCRIPTION

[0031] The following examples are further illustrations of the present application, and do not limit the present application.

[0032] Example 1:

[0033] The mature jackfruit is peeled and 2 kg of the peel is dried in an oven at 40°C for 36 hours. The dried jackfruit peel is ground into powder and filtered through a 80 mesh screen three times. The particles that are not filtered through the screen are ground into powder repeatedly until the final filtered powder is obtained. Rhizopus, rice powder and deionized water are mixed in a ratio of 10 g:500 g:1 kg and placed in a sealed container in a water bath at 30°C for 24 hours to obtain a fermentation liquid. Yeast is mixed with the fermentation liquid in a ratio of 10 g:1.5 kg and placed in a water bath at 30°C for 48 hours. The supernatant is obtained by filtering out the impurities with gauze. The jackfruit powder and deionized water are mixed in a ratio of 1.33 kg:20 kg to obtain a jackfruit suspension. The supernatant and the jackfruit suspension are added to the mixture in a ratio of 100 g:20 kg, stirred and placed in a sealed container. The mixture is placed in a water bath at 30°C for fermentation. After 3 days of fermentation, the fermentation liquid is filtered with a vacuum filter and a 100 um cloth funnel. The filtered liquid is filtered again with a 10 um filter membrane. The filtered fermentation liquid is heated to 90°C and maintained at this temperature. The dried silk cocoon pieces and the filtered fermentation liquid are added to a heatable container in a ratio of 1 kg:15 kg and maintained at 90°C for 60 minutes. The silk cocoon pieces are removed and washed with flowing water at 40°C for 3 times. The degumming process is repeated 5 times. The silk cocoon pieces are washed with flowing water at 40°C until no impurities are washed out. The silk cocoon pieces are removed and dried in an oven at 45°C. By comparison, the weight of the degummed and dried silk cocoon pieces is 800 g, and the degumming rate is 20%.

[0034] Example 2:

[0035] The mature jackfruit is deseeded, and 2 kg of the jackfruit peel is dried in an oven at a temperature of 50 °C for 36 hours. The dried jackfruit peel is ground into powder, and the powder is repeatedly filtered through an 80-mesh screen for 3 times. The particles that are not filtered through the screen are repeatedly ground into powder until they are finally filtered through the screen to obtain jackfruit peel powder for standby. Rhizopus, rice powder and deionized water are mixed in a ratio of 10 g: 500 g: 1 kg, and are placed in a sealed container and fermented in a water bath at 35 °C for 24 hours to obtain a fermentation liquor. Then, yeast is mixed with the fermentation liquor in a ratio of 10 g: 1.5 kg, and is continuously placed in a water bath at 35 °C for 48 hours. After that, the impurities are filtered out with gauze, and the supernatant is reserved for standby. The jackfruit powder and deionized water are mixed in a ratio of 2 kg: 20 kg to prepare a jackfruit suspension. The supernatant and the jackfruit suspension are added in a ratio of 100 g: 20 kg respectively, and are stirred uniformly. The mixed liquid is placed in a sealed container and is fermented in a water bath at 35 °C. After 5 days of sufficient fermentation, the fermentation liquor is filtered with a vacuum filter and a 100-μm cloth funnel. Then, the filtered liquid is filtered through a 10-μm filter membrane for standby. The filtered fermentation liquor is heated to 100 °C and kept at the temperature. The dried silk cocoon pieces and the filtered fermentation liquor are added in a ratio of 1 kg: 10 kg in a heatable container, and are kept at 100 °C. After 60 minutes of boiling, the silk cocoon pieces are taken out and washed with flowing water at 45 °C for 5 times. After 5 times of repeated boiling and washing, degumming is completed. The silk cocoon pieces are repeatedly washed with flowing water at 45 °C until no impurities are washed out. The silk cocoon pieces are taken out and are dried in an oven at 50 °C. By comparison, the weight of the dried cocoon pieces after degumming is 770 g, and the degumming rate of this embodiment is 23%.

[0036] By comparing the changes of the silk cocoon pieces before and after degumming, it is found that the softness and breaking strength of the cocoon pieces after degumming with the jackfruit fermentation liquor meet the standards, and the cocoon pieces have certain antibacterial property. It is observed by electron microscopy that there are attachments on the silk threads of the cocoon pieces after degumming with the fermentation liquor, which are mainly saponins and tannic acid, and are metabolites of the microbial fermentation of the jackfruit extraction. By comparing the weight difference of the dried cocoon pieces before and after degumming, the degumming rate of this scheme is 20% to 23%.

[0037] The above embodiments are illustrative of the present application, but are not limiting of the present application. Any simple transformation of the present application also belongs to the protection scope of the present application.

Claims

1. A method for degumming silkworm silk using microbial fermentation of Sapindus mukorossi extract, characterized in that, The process steps are: 1) The mature soapberry is deseeded, and the peel is dried in an oven at a temperature of 40-50°C for 36 hours. The dried soapberry peel is ground into powder, and the powder is repeatedly filtered through a 70-90 mesh screen for 3 times. The particles that are not filtered through the screen are repeatedly ground into powder until they are finally filtered through the screen to obtain soapberry peel powder for later use; 2) The Rhizopus, rice flour and deionized water are mixed in a ratio of 1:50:100, and placed in a closed container in a water bath at a temperature of 30-35°C for fermentation for 22-26 hours to obtain a fermentation liquid. The yeast and the fermentation liquid are mixed in a ratio of 1:150, and placed in a water bath at a temperature of 30-35°C for secondary fermentation for 46-50 hours. The fermentation liquid is filtered through gauze to remove impurities, and the supernatant is reserved for later use; 3) The soapberry powder and deionized water are mixed in a ratio of 1:10-15 to prepare a soapberry suspension; 4) The supernatant prepared in step 2) and the soapberry suspension prepared in step 3) are added in a ratio of 1:180-220, and stirred uniformly. The mixture is placed in a water bath at a temperature of 30-35°C for fermentation. After 3-5 days of fermentation, the fermentation liquid is obviously stratified, with precipitates at the bottom and a clear supernatant. At this time, the pH value of the fermentation liquid is 2.9-3.5, and the fermentation liquid is weakly acidic. The saponins in the soapberry are decomposed by fermentation, and a large amount of metabolic products are produced in the liquid; 5) The fermentation liquid obtained in step 4) is filtered through a vacuum filter and a 100-um cloth funnel to remove impurities. The filtered liquid is filtered through a 10-um filter membrane for later use; 6) The filtered fermentation liquid prepared in step 5) is heated to a temperature of 90-100°C and kept stable. The dried silk cocoon pieces and the filtered fermentation liquid are added in a ratio of 1:10-15 in a heatable container, and kept at a temperature of 90-100°C for boiling for 60 minutes. The silk cocoon pieces are removed, and washed with flowing water at a temperature of 40-45°C for 3-5 times; 7) After repeated boiling and washing for 5 times according to the method of step 6), the degumming is completed. The silk cocoon pieces are removed, and washed with flowing water at a temperature of 40-45°C until no impurities are washed out; 8) The silk cocoon pieces are removed, and dried in an oven at a temperature of 45-50°C.

2. A method for degumming of silk using microbial fermentation of sapindus mucronata extract as claimed in claim 1, wherein: In step 1), the soapberry peel is dried and ground into powder, and the powder is filtered through a 80-mesh screen for 3 times. The particles that are not filtered through the screen are repeatedly ground into powder until they are finally filtered through the screen.

3. A method for degumming of silk using microbial fermentation of sapindus mucronata extract as claimed in claim 1, wherein: In step 2), the fermentation time of the Rhizopus, rice flour and deionized water is 24 hours, and the secondary fermentation time after adding the yeast is 48 hours.

4. A method for degumming of silk using microbial fermentation of sapindus mucronata extract as claimed in claim 3, wherein: In step 2), the Rhizopus, rice flour and deionized water are used to prepare the fermentation liquid, and the fermentation temperature is 30-35°C. The yeast and the fermentation liquid are mixed for secondary fermentation, and the secondary fermentation temperature is 30-35°C.

5. A method for degumming of silk using microbial fermentation of sapindus mucronata extract as claimed in claim 1, wherein: In step 3), the soapberry powder and deionized water are mixed in a ratio of 1:12 to prepare a soapberry suspension.

6. A method for degumming of silk using microbial fermentation of sapindus mucronata extract as claimed in claim 1, wherein: In step 4), the ratio of the supernatant and the soapberry powder suspension is 1:200, the fermentation temperature is 33°C, and the fermentation time is 4 days.

7. A method for degumming of silk using microbial fermentation of sapindus mucronata extract as claimed in claim 1, wherein: In step 6), the weight ratio of silk cocoon piece to fermentation broth was 1:12; the fermentation broth temperature was 95°C; each time the silk was boiled in the fermentation broth for 60 min; the rinsing water temperature was 43°C; the silk was washed with flowing water 4 times.

8. A method of degumming silk with microbial fermentation of soapnut extract according to any one of claims 1 to 7, characterized in that: In step 8), the drying temperature was 48°C.

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