WO2024036996A1

WO2024036996A1 - Method for producing bacterial cellulose gel by directly utilizing livestock and poultry slaughtering tail water

Info

Publication number: WO2024036996A1
Application number: PCT/CN2023/087720
Authority: WO
Inventors: 冯玉红; 牛成; 林强; 赵振东; 李嘉诚; 刘海芳
Original assignee: 海南大学
Priority date: 2022-08-15
Filing date: 2023-04-12
Publication date: 2024-02-22
Also published as: CN117625712A

Abstract

Disclosed is a method for producing a bacterial cellulose gel by directly utilizing livestock and poultry slaughtering tail water. In the method, the livestock and poultry animal slaughtering tail water is precipitated, filtered, and prepared into a tail water culture medium, then acetobacter xylinum is inoculated into the prepared slaughtering tail water culture medium, and fermentation is performed to prepare the bacterial cellulose gel. The present invention solves the problems of an insufficient source of a plant-derived culture medium and high cost, omits the process that a traditional plant-derived culture medium needs to be fermented before it can be fully utilized by acetobacter xylinum to synthesize bacterial cellulose, and develops a new way for livestock and poultry slaughtering tail water treatment with difficult technology and high cost. The present invention directly utilizes rich nutrients in the livestock and poultry slaughtering tail water to synthesize the bacterial cellulose and achieves the conversion of the livestock and poultry slaughtering tail water into a bacterial cellulose gel product. The utilization rate of the tail water reaches 99.9% or more, and the obtained bacterial cellulose gel product meets the requirements of bacterial cellulose industrial production. The present invention opens a new scenario of biosynthesis of bacterial cellulose by using an animal-derived culture medium.

Description

A method of directly utilizing livestock and poultry slaughter tail water to produce bacterial cellulose gel

Technical field

The invention relates to a resource recycling method for livestock and poultry animal slaughter tail water, and specifically relates to a method of directly utilizing livestock and poultry animal slaughter tail water to produce bacterial cellulose gel, which belongs to the technical field of comprehensive utilization of industrial waste.

Background technique

According to a report by the Food and Agriculture Organization of the United Nations, global meat production has doubled in the past 30 years and is expected to double again by the end of 2050, so the amount of slaughter tail water will also increase. In 2004, the U.S. Environmental Protection Agency (USEPA) listed slaughter tailwater as wastewater discharge as one of the most harmful industrial wastewaters in the agricultural and food categories. Its discharge can lead to eutrophication of surface water bodies and pollution of groundwater. China's urban population is about 900 million. Taking livestock pigs as an example, based on the average annual consumption of at least 0.5 pigs per person and the production of 0.5-0.7 tons of tail water per pig slaughter, the pig slaughter tail water in China will produce at least 0.5 tons of tail water every year. 225 million tons. At present, wastewater from slaughtering and meat processing accounts for about 6% of the total industrial wastewater discharge in the country and 36.7% of the total wastewater discharge from the agricultural and sideline food processing industry. It is one of the important industrial wastewaters in my country.

Wastewater from livestock and poultry slaughtering and related meat processing is a typical organic wastewater. It is rich in protein and oil and does not contain toxic substances such as heavy metals. The main nutrients are carbon (C), nitrogen (N), and phosphorus (P). , which belongs to high-concentration organic wastewater. Among them, nitrogen mainly exists in the form of organic nitrogen or ammonium salt (NH ₄ ⁺ ), while phosphorus mainly exists in the form of organic phosphorus or phosphate (PO ₄ ^3- ). Nitrogen and phosphorus are considered to be one of the main factors leading to eutrophication of water bodies, which are toxic to aquatic organisms. The Ministry of Environmental Protection, together with the General Administration of Quality Supervision and Inspection, launched the revision of the "Water Pollutant Discharge Standard for the Meat Processing Industry" (GB 13457-1992) in 2017 (hereinafter referred to as the new standard). The new standard clearly requires direct TN≤25mg/L, TP≤2mg/L in discharged wastewater, TN≤70mg/L, TP≤8mg/L in indirect discharged wastewater. At present, biological treatment processes or biochemical-based physicochemical and biochemical combination processes are often used at home and abroad to treat slaughtering wastewater. Therefore, it is technically difficult to treat slaughter tailwater as industrial wastewater discharge, and the treatment cost is high, which places a heavy burden on enterprises and causes a waste of biomass resources.

Bacterial cellulose (BC) is a natural macromolecule with a super-fibrous network structure connected by β-1,4 glycosidic bonds. Its diameter is only 1.5nm. It has high crystallinity, chemical purity, Mechanical strength, adsorption capacity and good biodegradability. Bacterial cellulose gel is prepared by biological culture method. In recent years, Feng Yuhong and others have biosynthesized bacterial cellulose with low relative molecular weight and in situ biosynthesized glyceraldehyde-modified bacterial cellulose. Niu Cheng et al. synthesized a three-dimensional structure nanobacterial cellulose gel by static culture in Acetobacter xylinum culture medium using coconut water as raw material. Ma Yinghui et al. discussed the process parameters of producing bacterial cellulose using straw hydrolyzate as the only carbon source, and compounding bacterial cellulose with bleached sulfate hardwood pulp can enhance the abrasion resistance and breaking strength of paper. The unique texture structure and excellent performance of bacterial cellulose gel, Bacterial cellulose synthesized from traditional coconut water culture media has been widely used in the food industry, paper industry, membrane materials, medical materials and other fields. Up to now, literature research reports on the biosynthesis of bacterial cellulose by Acetobacter xylin mostly use plant-derived culture media or Hestrin S.-Schramm M. standard culture media. There has been no use of animal-derived culture media to biosynthesize bacterial cellulose.

Contents of the invention

In view of the problem of high production cost of bacterial cellulose due to the limited source of plant-derived culture medium, and the problem that the nutrients in the plant-derived culture medium cannot be directly utilized by Acetobacter xylinum but must be fermented to be used as a culture medium to synthesize bacterial cellulose. As well as the problem of technical difficulty and high cost in treating a large amount of tail water produced by the slaughter of livestock and poultry animals, the present invention provides a method for directly utilizing the tail water from the slaughter of livestock and poultry animals to produce bacterial cellulose gel. This method directly utilizes the tail water from the slaughter of livestock and poultry animals. Small molecule peptides, nitrogen, phosphorus, inorganic salts and other nutrients in the tail water are used to produce bacterial cellulose gel, which eliminates the need for nutrients in plant-derived culture media that cannot be directly utilized by Acetobacter xylin and must undergo pre-fermentation before they can be used as culture media. The process and time of synthesizing bacterial cellulose also solve the multiple problems of livestock and poultry slaughter tailwater being discharged as wastewater, such as high nitrogen and phosphorus content, high COD, high oil content, and high processing cost, and fully recycle and utilize the biomass in the tailwater. resources, realize the high-value transformation of waste, achieve the purpose of turning waste into treasure, greatly reduce or eliminate the cost of slaughtering tail water treatment, and increase the added value of the livestock and poultry slaughtering and processing industry, extending the time of livestock and poultry slaughtering and processing. Industrial chain, at the same time, the tail water from livestock and poultry slaughter can be directly used to produce bacterial cellulose with only simple filtration. Not only is the culture medium resource rich and cheap, it also simplifies and shortens the process, greatly reducing the production cost of bacterial cellulose. , achieving the effect of "killing two birds with one stone", in line with the concept of industrial green development.

The invention opens up a new situation in the biosynthesis of bacterial cellulose using animal-derived culture media, and eliminates the need for fermentation of plant-derived culture media before it can be used as a bacterial cellulose culture medium, thus opening up resources for livestock and poultry animal slaughter tail water. A new way of chemical utilization has opened up new resources of high-quality, abundant and low-price culture media for bacterial cellulose, which has greatly reduced the production cost of bacterial cellulose. The specific technical solutions are as follows:

A method for producing bacterial cellulose gel directly by using tail water from slaughtering livestock and poultry animals, the method includes the following steps:

(1) Filter the tail water from slaughtering livestock and poultry animals to obtain the tail water filtrate;

(2) Add at least one of the carbon source, nitrogen source and inorganic salt required for Acetobacter xylinum fermentation to the tailwater filtrate, and then adjust the pH to 4-4.5 to prepare a slaughter tailwater culture medium;

(3) Inoculate Acetobacter xylinum into the prepared slaughter tail water culture medium and ferment it to obtain bacterial cellulose gel.

Furthermore, the tail water from livestock and poultry animal slaughter refers to the blood-containing wastewater produced during the slaughtering process of livestock and poultry animals, such as livestock pigs, cattle, sheep and poultry chickens, ducks, geese, etc. produced during the slaughtering process. tailwaters and their mixtures. Tail water mainly contains a large amount of blood, oil, fur, bone residue, meat residue, visceral debris and some undigested food. These tailwaters generally have the characteristics of high COD, high oil content and high solids. The COD value in the tailwater is generally greater than 10 ⁴ mg/L. The main nutrients in the filtered tail water are carbon (C), nitrogen (N), and phosphorus (P). Nitrogen is mainly in the form of organic nitrogen or ammonium salt (NH ₄ ⁺ ). Formula exists, and phosphorus mainly exists in the form of organic phosphorus or phosphate (PO ₄ ^3- ). These substances can provide rich nutrients for the growth of Acetobacter xylinum and its synthesis of bacterial cellulose. If the nutrients in the tailwater do not meet this requirement, appropriate nutrients can be added to it to meet the requirements.

Further, in step (1), the tail water from slaughtering livestock and poultry animals is first filtered to remove solid matter. Filtration is carried out using a filter screen with a mesh size of 60-100 mesh.

Further, in step (2), in order to meet the needs of Acetobacter xylin fermentation, components required for fermentation such as carbon source, nitrogen source and inorganic salt can be added in appropriate amounts according to the conditions of the tail water. The carbon source, nitrogen source and inorganic salts can be selected from the carbon sources, nitrogen sources and inorganic salts reported in the prior art that can be used for Acetobacter xylin fermentation. For example, the carbon source can be at least one of sucrose, fructose and glucose. Preferably it is sucrose; the nitrogen source is at least one of ammonium sulfate, yeast powder, peptone and corn steep liquor, preferably ammonium sulfate; the inorganic salt is at least one of potassium dihydrogen phosphate, magnesium sulfate and sodium acetate, preferably phosphoric acid A mixture of potassium dihydrogen, magnesium sulfate, and sodium acetate. Potassium dihydrogen phosphate can provide the phosphorus and potassium elements needed for the metabolism of Acetobacter xylin. Magnesium sulfate can provide the magnesium element needed for the metabolism of Acetobacter xylin. Sodium acetate can also act as a buffer to avoid degradation of the culture medium during the culture process. Large changes in pH value affect the growth of bacteria, and can also be used as a nutrient source for Acetobacter xylinum.

Further, in step (2), the content of the carbon source in the tail water filtrate is 0-4wt%, preferably 2.5-4wt%; the content of the nitrogen source in the tail water is 0-0.4wt%, preferably 0-0.3 wt%; the content of inorganic salt in tail water is 0.3-1.3wt%, preferably 0.3-1.1wt%.

In a specific embodiment of the invention, the carbon source is sucrose with a content of 2.5-4wt%; the nitrogen source is ammonium sulfate with a content of 0-0.3%; the inorganic salt is a mixture of potassium dihydrogen phosphate, magnesium sulfate and sodium acetate. , the content of potassium dihydrogen phosphate in the tail water culture medium is 0-0.4wt%, the content of magnesium sulfate in the tail water culture medium is 0.05-0.5wt%, and the content of sodium acetate in the tail water culture medium is 0.2- 0.5wt%.

Further, in step (2), acetic acid is used to adjust the pH to 4-4.5. The acetic acid can be table vinegar or glacial acetic acid. Acetic acid and sodium acetate can form a stable buffer to avoid excessive changes in the pH value of the culture solution during the culture process, which may affect the growth of Acetobacter xylinum and the synthesis of bacterial cellulose.

Further, in step (3), the slaughter tail water culture medium is first sterilized at high temperature, and then inoculated with Acetobacter xylinum. The inoculum amount of Acetobacter xylinum is 3-10wt%. High temperature sterilization can use commonly used sterilization conditions, such as sterilization at 100-120°C for 10-20 minutes. If the temperature is too high or the heating time is too long, the nutrients in the culture medium will be destroyed.

Further, in step (3), the fermentation temperature is 25-35°C. Too low a temperature is not conducive to the growth of Acetobacter xylinum, and too high a temperature will also inhibit the growth of the bacteria. Fermentation time is generally 5-9 days.

In step (3), the bacterial cellulose gel obtained after fermentation can be washed with water and then compressed and dehydrated to obtain a bacterial cellulose gel product; the liquid obtained by washing and compressing and dehydrating is reused to prepare the slaughter tail water culture medium.

Further, after the Acetobacter xylinum fermentation is completed, the bacterial cellulose gel formed is washed with water. The purpose of water washing is to remove bacterial contaminants on the surface. The washed bacterial cellulose gel can be used directly, or it can be compressed and dehydrated to obtain a concentrated bacterial cellulose gel product. Compression and dehydration can save a lot of storage space and transportation costs. The operation method is: using a large tablet press for compression processing, the compression rate can reach 1/12. The bacterial cellulose gel product obtained by compression and dehydration can adjust the pH value to Sterilize and store after 3.5-5 minutes. The lower pH value is beneficial to the long-term storage of bacterial cellulose gel. The bacterial cellulose gel product finally obtained is of excellent quality and has a bacterial cellulose content of 0.7-20wt%.

Further, the tail water obtained by washing the bacterial cellulose gel is filtered to filter out the solid waste. The filtered washing water and the tail water obtained during the compression and dehydration process can be recycled and added to the next batch of tail water to continue. Treating according to the method of the present invention reduces the discharge of tail water.

The present invention uses livestock and poultry slaughter tail water as raw material and is directly used as Acetobacter xylinum culture medium to synthesize bacterial cellulose gel. Compared with the existing technology, this method has the following advantages:

1. The present invention directly utilizes livestock and poultry slaughtering tailwater to produce high value-added bacterial cellulose gel and products. The obtained bacterial cellulose gel and products meet the requirements for industrial production of bacterial cellulose. The present invention opens up a new situation in the biosynthesis of bacterial cellulose using animal-derived culture media, and eliminates the need for fermentation of plant-derived culture media before it can be used as a bacterial cellulose culture medium. It simplifies the industrial production process of bacterial cellulose and saves money. Reduce costs such as energy and production cycle and improve production efficiency.

2. The present invention can not only solve multiple problems such as high COD, high oil content, high treatment cost, and environmental pollution in tail water discharged as wastewater during the slaughtering and processing of livestock and poultry animals, but also can fully recycle and utilize the rich biomass resources in the tail water. It has realized the transformation of industrial waste into high value-added products, achieved the purpose of turning waste into treasure, extended the livestock and poultry slaughtering and processing industry chain, increased the added value of the slaughtering and processing industry, and is in line with the concept of industrial green development.

3. The present invention effectively increases the added value of the livestock and poultry slaughtering and processing industry, reduces or even eliminates the cost of tail water treatment for slaughtering and processing enterprises. At the same time, it breaks through the dilemma of limited sources of plant-derived culture media and opens up new opportunities for high-quality, abundant and affordable products. The low-cost animal-derived culture medium greatly reduces the production cost of bacterial cellulose gel, achieving the effect of "killing two birds with one stone". It not only brings huge economic benefits to enterprises, but also has social and ecological benefits of extending the industrial chain and reducing pollution. It is very significant and will help promote the sustainable and healthy development of my country's breeding and slaughtering industry and its related processing industries.

4. The slaughter tail water of the present invention only needs simple filtration to produce bacterial cellulose. The process is simple, low cost, green and environmentally friendly, and can be recycled to synthesize bacterial cellulose. The tail water recycling rate can reach more than 99.9wt%, which greatly reduces emissions of three wastes.

5. The present invention makes full use of the rich carbon, nitrogen, phosphorus and other nutrients in the slaughter tail water of livestock and poultry animals to synthesize bacterial cellulose, and realizes the conversion of slaughter tail water into bacterial cellulose gel products, and the obtained bacterial cellulose gel The product meets the requirements for industrial production of bacterial cellulose.

Description of drawings

Figure 1 is a diagram of the slaughter tail water after filtration.

Figure 2 is a diagram of the bacterial cellulose gel obtained in Example 1.

Detailed ways

The present invention will be further explained and described below through specific embodiments. The following description is only exemplary and does not limit its content. In the following examples, unless otherwise stated, the concentrations mentioned are mass concentrations.

In the following examples, the Acetobacter xylinum used is A. Microbial Products Company); yeast, Aspergillus and acetic acid bacteria can be purchased from commercial products. The yeast used in this study was purchased from Angel Yeast Co., Ltd., and the Aspergillus and acetic acid bacteria used were purchased from Yiyuan Kangyuan Biotechnology Co., Ltd.

Example 1

1. Take the slaughtered pig tail water, let it settle for 1-3 hours, pass it through a 100-mesh filter, remove large solid particles, and get the slaughtered tail water filtrate, as shown in Figure 1.

2. Take the above tail water filtrate, add 3wt% sucrose, 0.1wt% ammonium sulfate, 0.2wt% potassium dihydrogen phosphate, 0.3wt% sodium acetate, 0.05wt% magnesium sulfate, acetic acid based on the tailwater filtrate. Adjust the pH value to 4.5 to obtain the production medium. Put the production culture medium into a plate, seal it, and keep it at 120°C for 10 minutes for sterilization and set aside.

3. Inoculate Acetobacter xylinum liquid species according to the amount of 7wt% of the production medium, and culture it at 30°C for 6 days to obtain bacterial cellulose gel. Rinse the bacterial cellulose gel with tap water to remove impurities such as bacteria attached to the surface of the gel. The resulting debris is filtered and discharged, accounting for approximately 0.1wt% of the tail water mass.

4. The appearance of the washed bacterial cellulose gel is shown in Figure 2. It is slightly brown and transparent and has no peculiar smell. The cleaned bacterial cellulose is compressed to obtain a bacterial cellulose gel with a compression rate of 1/10, the pH value is adjusted to 4, and sterilized and stored to obtain a bacterial cellulose gel product with a bacterial cellulose content of approximately 7wt%. The bacterial cellulose gel product has a slightly brown appearance and no peculiar smell.

5. The compressed solution and the filtered washing water are added to the next batch of slaughter tail water for recycling and reuse, and the bacterial cellulose gel is cultured. The utilization rate of the slaughter tail water filtrate (tail water utilization rate = 1-tail The solid content in water) is approximately 99.9wt%.

Example 2

1. Take the slaughtered ox tail water, let it settle for 1-3 hours, pass it through an 80-mesh filter to remove large solid particles, and get the slaughtered tail water filtrate.

2. Take the above tail water filtrate and add 3.5wt% sucrose, 0.2wt% ammonium sulfate, 0.4wt% potassium dihydrogen phosphate, 0.4wt% sodium acetate, and 0.05wt% magnesium sulfate based on the tailwater filtrate. Adjust the pH value to 4.4 with acetic acid to obtain the production medium. Will The production culture medium is loaded into plates, sealed, and sterilized at 115°C for 10 minutes before use.

3. Inoculate Acetobacter xylinum liquid species at an amount of 6wt% of the production culture medium, and culture it at 32°C for 7 days to obtain bacterial cellulose gel. Rinse the bacterial cellulose gel with tap water to remove impurities such as bacteria attached to the surface of the gel. The resulting debris is filtered and discharged, accounting for approximately 0.1wt% of the tail water mass.

4. After cleaning, the bacterial cellulose gel is slightly brown and transparent, with no peculiar smell. The cleaned bacterial cellulose is compressed to obtain a bacterial cellulose gel with a compression rate of 1/8, the pH value is adjusted to 4, and sterilized and stored to obtain a bacterial cellulose gel product with a bacterial cellulose content of approximately 6wt%. The bacterial cellulose gel product has a slightly brown appearance and no peculiar smell.

Example 3

1. Take the slaughtered sheep tail water, let it settle for 1-3 hours, pass it through a 60-mesh filter, remove large solid particles, and get the slaughtered tail water filtrate.

2. Take the above tail water filtrate, add 4wt% sucrose, 0.3wt% ammonium sulfate, 0.5wt% potassium dihydrogen phosphate, 0.5wt% sodium acetate, 0.05wt% magnesium sulfate, acetic acid based on the tailwater filtrate. Adjust the pH value to 4.3 to obtain the production medium. Put the production culture medium into a plate, seal it, and keep it at 115°C for 10 minutes for sterilization and set aside.

3. Inoculate Acetobacter xylinum liquid species at an amount of 5wt% of the production culture medium, and culture it at 32°C for 8 days to obtain a bacterial cellulose gel. Rinse the bacterial cellulose gel with tap water to remove impurities such as bacteria attached to the surface of the gel. The resulting debris is filtered and discharged, accounting for approximately 0.1wt% of the tail water mass.

4. After cleaning, the bacterial cellulose gel is slightly brown and transparent, with no peculiar smell. The cleaned bacterial cellulose is compressed to obtain a bacterial cellulose gel with a compression rate of 1/12, the pH value is adjusted to 4, and sterilized and stored to obtain a bacterial cellulose gel product with a bacterial cellulose content of approximately 11wt%. The bacterial cellulose gel product has a slightly brown appearance and no peculiar smell.

Example 4

1. Take the slaughtered chicken tail water, let it settle for 1-3 hours, and pass it through an 80-mesh filter to remove large solid particles to obtain the slaughtered chicken tail water filtrate.

2. Take the above tail water filtrate and add 3.5wt% sucrose, 0.05wt% ammonium sulfate, 0.1wt% potassium dihydrogen phosphate, 0.3wt% sodium acetate, 0.05wt% magnesium sulfate based on the tailwater filtrate. Adjust the pH value to 4.2 with acetic acid to obtain the production medium. Put the production culture medium into a plate, seal it, and keep it at 105°C for 10 minutes for sterilization and set aside.

3. Inoculate Acetobacter xylinum liquid species according to 8wt% of the production medium, and culture it at 33°C for 6 days to obtain bacterial fiber. To make bacterial cellulose gel, rinse the bacterial cellulose gel with tap water to remove impurities such as bacteria attached to the gel surface. The obtained impurities are filtered and discharged, accounting for approximately 0.1wt% of the tail water mass.

4. After cleaning, the bacterial cellulose gel is slightly brown and transparent, with no peculiar smell. The cleaned bacterial cellulose is compressed to obtain a bacterial cellulose gel with a compression rate of 1/10, the pH value is adjusted to 4, and sterilized and stored to obtain a bacterial cellulose gel product with a bacterial cellulose content of approximately 7wt%. The bacterial cellulose gel product has a slightly brown appearance and no peculiar smell.

Example 5

1. Mix the slaughtered pig tail water and duck tail water, let settle for 1-3 hours, pass through a 100-mesh filter to remove large solid particles, and obtain the slaughtered tail water filtrate.

2. Take the above tail water filtrate, add 2.5wt% sucrose, 0.2wt% sodium acetate, 0.05wt% magnesium sulfate based on the tailwater filtrate, and adjust the pH value to 4.0 with acetic acid to obtain a production medium. Put the production culture medium into a plate, seal it, and keep it at 105°C for 15 minutes for sterilization and set aside.

3. Inoculate Acetobacter xylinum liquid species according to 10wt% of the production medium, and culture it at 35°C for 5 days to obtain bacterial cellulose gel. Rinse the bacterial cellulose gel with tap water to remove impurities such as bacteria attached to the surface of the gel. The resulting debris is filtered and discharged, accounting for approximately 0.1wt% of the tail water mass.

4. After cleaning, the bacterial cellulose gel is slightly brown and transparent, with no peculiar smell. The cleaned bacterial cellulose is compressed to obtain a bacterial cellulose gel with a compression rate of 1/12, the pH value is adjusted to 4, and sterilized and stored to obtain a bacterial cellulose gel product with a bacterial cellulose content of approximately 12wt%. The bacterial cellulose gel product has a slightly brown appearance and no peculiar smell.

Comparative example 1

Referring to the steps of Example 1 of patent CN201010113232. Potassium dihydrogen phosphate 1g/L, sodium acetate 2g/L, and the rest are supplemented with tap water, pH 4.2), sterilized at 100°C for 30 minutes; add 5% of the inoculum amount to the production medium, and maintain it at 25-35°C Let it stand for 5-7 days; compress and decolorize, and the compressed liquid will be precipitated, filtered, and recovered. Reconstitute the culture medium with the recovery liquid as the main culture medium (600g/L recovery liquid, 100g/L fermented coconut water, 20g/L sucrose, 3g/L diammonium phosphate, 0.5g/L magnesium sulfate, 1g/L potassium dihydrogen phosphate/ L, sodium acetate 2g/L, the rest is supplemented with tap water, pH 4.2), Sterilize at 100°C for 30 minutes; insert 5% of the inoculum into the production medium, and incubate at 25-35°C for 5-7 days; compress and decolorize, the compressed liquid is precipitated and filtered, and the culture medium can be re-configured for repeated cultivation , the weight ratio of the compressed coconut fruit to the coconut fruit before compression is 1:5; the compressed fruit slices are rehydrated and then cut and sterilized to make the finished coconut fruit. It can be seen that using coconut water as raw material requires pre-fermentation of coconut water in advance, which increases the operating process and production cycle, and the corresponding production cost will be higher.

Comparative example 2

Refer to the steps of Example 1 of patent 202210484679.0 as follows:

1. Take coconut juice production tail water, pass it through a 60-mesh filter, remove large solid particles, and obtain milky white tail water with a COD value of approximately 1.2×10 ⁴ mg/L.

2. Add 1wt% starch of the tail water mass to the production tail water after impurity removal, stir evenly, boil for 10 minutes, cool to room temperature, inoculate compound microorganisms with a tail water mass of 3×10 ^-5 , and conduct open fermentation at 32°C until the end Stop the fermentation after the water has no bubbles and no obvious oil layer on the surface. Pass it through a 100-mesh filter to remove fermented floating matter and sediment to obtain the tail water fermentation liquid of coconut juice production. The total acidity of organic acids is about 0.6wt%. Filter The solid waste obtained accounts for about 0.3% of the tail water mass, and no foul smell is produced in the whole process.

3. Take the above tail water fermentation liquid and add 2wt% sucrose, 0.5wt% ammonium sulfate, 0.3wt% potassium dihydrogen phosphate, 0.3wt% sodium acetate, and 0.05wt% magnesium sulfate based on the tail water fermentation liquid. , adjust the pH value to 4.5 to obtain the production medium. Put the production culture medium into a plate, seal it, and keep it at 120°C for 10 minutes for sterilization and set aside.

4. Inoculate Acetobacter xylinum liquid species according to the amount of 7wt% of the production medium, and culture it at 30°C for 6 days to obtain bacterial cellulose gel. Rinse the bacterial cellulose gel with tap water to remove impurities such as bacteria attached to the surface of the gel. The resulting debris is filtered and discharged, accounting for approximately 0.1wt% of the tail water mass.

5. The washed bacterial cellulose gel is milky white and transparent, with no odor. The cleaned bacterial cellulose is compressed to obtain a bacterial cellulose gel with a compression rate of 1/10, the pH value is adjusted to 4, and sterilized and stored to obtain a bacterial cellulose gel product with a bacterial cellulose content of approximately 8wt%. The bacterial cellulose gel product has a slightly yellow appearance and no peculiar smell.

6. Add the compressed solution and filtered washing water to the next batch of coconut juice production tail water, and keep the COD value not less than 5×10 ³ mg/L for recycling and culturing bacterial cellulose gel. , the tail water utilization rate of coconut juice processing (tail water utilization rate = 1-the solid content in the tail water) is about 99.6wt%.

It can be seen that using tail water from coconut juice production as raw material also requires fermentation pretreatment, which increases the operating process and production cycle, and the corresponding production cost will be higher.

Claims

A method for producing bacterial cellulose gel directly using the tail water from slaughtering livestock and poultry animals, which is characterized by:

(1) Filter the tail water from slaughtering livestock and poultry animals to obtain the tail water filtrate;

(2) Add at least one of the carbon source, nitrogen source and inorganic salt required for Acetobacter xylinum fermentation to the tailwater filtrate, and then adjust the pH to 4-4.5 to prepare a slaughter tailwater culture medium;

(3) Inoculate Acetobacter xylinum into the prepared slaughter tail water culture medium and ferment it to obtain bacterial cellulose gel.
The method according to claim 1, characterized in that: the livestock and poultry animal slaughter tail water refers to the blood-containing wastewater produced during the slaughter of livestock and poultry animals; the livestock and poultry animals are mainly selected from pigs , cow, sheep, chicken, duck or goose.
The method according to claim 1, characterized in that: in step (1), filtering is performed using a filter screen, and the mesh number of the filter screen is 60-100 mesh.
The method according to claim 1, characterized in that: in step (2), the carbon source is at least one of sucrose, fructose, and glucose; the nitrogen source is ammonium sulfate, yeast powder, peptone, and corn steep liquor. At least one of them; the inorganic salt is at least one of potassium dihydrogen phosphate, magnesium sulfate, and sodium acetate.
The method according to claim 1 or 4, characterized in that: in step (2), the content of the carbon source in the tail water filtrate is 0-4wt%; the content of the nitrogen source in the tail water filtrate is 0-0.4wt %; the content of inorganic salts in tail water is 0.3-1.3wt%.
The method according to claim 1, characterized in that: in step (2), the carbon source is sucrose, the nitrogen source is ammonium sulfate, and the inorganic salt is potassium dihydrogen phosphate, magnesium sulfate, or sodium acetate. Mixture; in step (2), the content of the carbon source in the tail water filtrate is 2.5-4wt%, the content of the nitrogen source in the tail water filtrate is 0-0.3wt%, and the content of inorganic salts in the tail water is 0.3-1.1 wt%.
The method according to claim 1, characterized in that: in step (2), acetic acid is used to adjust the pH to 4-4.5.
The method according to claim 1, characterized in that: in step (3), the slaughter tail water culture medium is first sterilized at high temperature, and then inoculated with Acetobacter xylinum.
The method according to claim 1, characterized in that in step (3), the inoculum amount of Acetobacter xylinum is 3-10wt%.
The method according to claim 1, characterized in that: in step (3), the fermentation temperature is 25-35°C, and the fermentation time is 5-9 days; in step (3), the bacterial cellulose gel obtained after fermentation Wash with water and then compress and dehydrate to obtain a bacterial cellulose gel product. The liquid obtained by washing and compressing and dehydrating is reused to prepare the slaughter tail water culture medium.