A method for the preparation and use of a cellulose-based film material for food detection
By preparing cellulose and anthocyanin-based membrane materials, the problems of high cost, complex response modes, serious pollution, and difficult recycling of traditional pH-stimulated membrane materials are solved. This provides a low-cost, easy-to-recycle, and highly responsive food detection method suitable for general consumers.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-01-17
- Publication Date
- 2026-03-24
AI Technical Summary
Existing pH-responsive membrane materials have high production costs, complex response modes, serious pollution, insignificant changes, and are difficult to recycle, making it difficult to meet the needs of mass consumers.
Using cellulose and anthocyanins as raw materials, a nanocellulose suspension was prepared through steps such as diluted sulfuric acid hydrolysis, centrifugation dialysis, and ultrasonic treatment. The suspension was then mixed with anthocyanins, evaporated, and dried to form a cellulose-based membrane material. The color change of anthocyanins under pH stimulation was used for food detection.
It achieves low-cost, simple response mode, low pollution, obvious color change and easy recycling of food detection, is suitable for general consumers, and can show color differences in the visible light region, making it suitable for daily low-temperature environments.
Smart Images
Figure CN116183592B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to a preparation method and application of a cellulose-based film material. BACKGROUND
[0002] At present, there are many high-sensitivity pH stimulus response film materials driven by electricity, light and the like on the market, but there are still many shortcomings:
[0003] 1. High production cost: traditional pH stimulus response film materials rely on supporting instruments, have high use cost, and the conductive raw materials used in the production process are difficult to produce and have high price, making industrialization difficult.
[0004] 2. Complex response mode: traditional pH stimulus response film materials detect the change in conductivity at different pH values by using instruments, thereby achieving detection of the environmental pH, which is complex and has high technical requirements, and is not suitable for mass consumers.
[0005] 3. High pollution: the by-products generated in the preparation process have certain toxicity, which has adverse effects on environmental protection and human health.
[0006] 4. Insignificant change process: the change in potential is not strongly intuitive, and the change process of the reflection and absorption spectrum of the traditional pH stimulus response film material falls in the invisible light region, and the product does not have obvious color change.
[0007] 5. Difficult to recycle: after the preparation of the traditional pH stimulus response film material is completed, the monomers are connected by covalent bonds, and the bonding strength between them is large, which cannot be broken by simple means, the material is difficult to degrade, and the degradation process is easy to cause secondary pollution. SUMMARY
[0008] The purpose of the present application is to solve the problems of high production cost, complex response mode, high pollution, insignificant change process and difficult recycling of the pH stimulus response film material prepared by the existing method, and to provide a preparation method and application of a cellulose-based film material for food detection.
[0009] A preparation method of a cellulose-based film material for food detection is completed according to the following steps:
[0010] I. Preparation of nanocellulose suspension:
[0011] ①, dilute concentrated sulfuric acid with a mass fraction of 98% to obtain a sulfuric acid solution with a mass fraction of 62.5%-64%;
[0012] ② Mix cotton lint with a sulfuric acid solution with a mass fraction of 62.5% to 64%, carry out hydrolysis under stirring, then add deionized water, and then centrifuge and dialyze to obtain a primary nanocellulose solution.
[0013] ③ The primary nanocellulose solution is centrifuged multiple times to remove impurities, then treated with an ultrasonic pulverizer, and then concentrated in an oven at a temperature of 45℃~60℃ to obtain a nanocellulose suspension with a mass fraction of 1.17%~1.62%.
[0014] II. Preparation of cellulose-based membrane materials:
[0015] Anthocyanin solution and ethylene glycol were dissolved in a nanocellulose suspension with a mass fraction of 1.17% to 1.62% to obtain a mixed solution. The mixed solution was placed on a flat table at 25°C and 50% relative humidity for evaporation, drying and self-assembly to obtain a cellulose-based membrane material for food testing.
[0016] Advantages of this invention:
[0017] I. Low production cost: The main raw materials required for the production process are all plant-based biomass materials, and their green, environmentally friendly and economically efficient characteristics determine their high comprehensive value.
[0018] II. Simple Response Mode: This invention uses the color change of anthocyanins under pH stimulation as the mechanism. While maintaining the high sensitivity of traditional pH stimulation response membrane materials, it does not require a large detection system. Food freshness can be confirmed by visually judging the color change of the membrane, which simplifies the response mode. Alternatively, by plotting standard curves of the sample transmission spectrum at different pH levels, semi-quantitative measurement of ammonia can be achieved, and freshness can be quantitatively judged.
[0019] 3. Low environmental pollution: Made from anthocyanins and cellulose, it is biodegradable, renewable, biocompatible, and pollution-free.
[0020] IV. Strong Changes: The spectral changes of samples prepared by this process fall within the visible light region. As the fresh shrimp decomposes, the color changes from red to gray to orange, which is easily noticeable.
[0021] V. Simple separation and easy recycling of raw materials: In the cellulose-based membrane material for food testing prepared by this invention, cellulose and anthocyanins are connected by hydrogen bonds and van der Waals forces. The bond strength is small. Anthocyanins can be obtained by adding a small amount of water and filtering. Then, a nano-cellulose solution can be obtained by heating a small amount of water.
[0022] VI. This invention uses ethylene glycol as a plasticizer: Unlike other plasticizers that reduce brittleness and increase toughness, ethylene glycol, as a plasticizer, not only meets the basic requirements of a plasticizer, but can also exist in the product as an antifreeze agent, making the food freshness indicator suitable for low-temperature conditions in daily life.
[0023] This invention provides a cellulose-based membrane material for food testing. Attached Figure Description
[0024] Figure 1 Macroscopic images of the cellulose-based membrane material for food testing prepared in Example 1 under different polarized light, where (a) is natural light, (b) is left-handed light, and (c) is right-handed light;
[0025] Figure 2 SEM images of amorphous nanocellulose films and cellulose-based membrane materials for food detection prepared in Example 1, wherein (a) is an amorphous nanocellulose film without chiral structure, and (b) is a cellulose-based membrane material for food detection prepared in Example 1 with chiral structure.
[0026] Figure 3 The visible light absorption spectra of the cellulose-based membrane material solutions for food detection prepared in Example 1 under different environmental pH values are shown. Among them, the pH value of a is 3, the pH value of b is 4, the pH value of c is 7, the pH value of d is 9, and the pH value of e is 11.
[0027] Figure 4 The morphological changes of the cellulose-based membrane material for food testing prepared in Example 1 under different humidity conditions are shown in the figure.
[0028] Figure 5 Reflectance spectra of cellulose-based membrane materials for food testing prepared in Example 1 under different humidity conditions, wherein the humidity of 1 is 50%, the humidity of 2 is 70%, the humidity of 3 is 80%, the humidity of 4 is 90%, and the humidity of 5 is 100%.
[0029] Figure 6 The graph shows the spoilage of fresh shrimp under refrigerated conditions at 4°C and natural conditions at 25°C, using the cellulose-based membrane material prepared in Example 1 for food detection as a food freshness indicator, and the response of the food freshness indicator under the corresponding conditions.
[0030] Figure 7 Using the cellulose-based membrane material prepared in Example 1 for food testing as a food freshness indicator, the standard curves of the transmission spectrum of the food freshness indicator at different pH values are shown. In the figure, the pH value of a is 3, the pH value of b is 4, the pH value of c is 5, the pH value of d is 6, the pH value of e is 7, the pH value of f is 8, the pH value of g is 9, the pH value of h is 10, and the pH value of I is 11. Detailed Implementation
[0031] Specific Implementation Method 1: This implementation method describes a method for preparing a cellulose-based membrane material for food testing, specifically completed according to the following steps:
[0032] I. Preparation of nanocellulose suspension:
[0033] ① Dilute concentrated sulfuric acid with a mass fraction of 98% to obtain a sulfuric acid solution with a mass fraction of 62.5% to 64%;
[0034] ② Mix cotton lint with a sulfuric acid solution with a mass fraction of 62.5% to 64%, carry out hydrolysis under stirring, then add deionized water, and then centrifuge and dialyze to obtain a primary nanocellulose solution.
[0035] ③ The primary nanocellulose solution is centrifuged multiple times to remove impurities, then treated with an ultrasonic pulverizer, and then concentrated in an oven at a temperature of 45℃~60℃ to obtain a nanocellulose suspension with a mass fraction of 1.17%~1.62%.
[0036] II. Preparation of cellulose-based membrane materials:
[0037] Anthocyanin solution and ethylene glycol were dissolved in a nanocellulose suspension with a mass fraction of 1.17% to 1.62% to obtain a mixed solution. The mixed solution was placed on a flat table at 25°C and 50% relative humidity for evaporation, drying and self-assembly to obtain a cellulose-based membrane material for food testing.
[0038] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that: the volume ratio of the cotton lint to the 62.5%–64% sulfuric acid solution in step one, step two, is (34g–30g):600mL; the volume ratio of the 62.5%–64% sulfuric acid solution to deionized water in step one, step two, is 600:(2400–2800). All other steps are the same as in Specific Implementation Method One.
[0039] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that: the stirring speed in step one ② is 1850 r / min to 2000 r / min; the hydrolysis reaction time in step one ② is 60 min to 70 min. Other steps are the same as in Specific Implementation Method One or Two.
[0040] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that: the power of the ultrasonic pulverizer mentioned in step one ③ is 800W; the processing time using the ultrasonic pulverizer in step one ③ is 270s to 300s. The other steps are the same as in Specific Implementation Methods One to Three.
[0041] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the concentration of the anthocyanin solution mentioned in step two is 2 mg / mL to 2.1 mg / mL. The other steps are the same as in Specific Implementation Methods One to Four.
[0042] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the volume ratio of the anthocyanin solution, ethylene glycol, and nanocellulose suspension with a mass fraction of 1.17% to 1.62% in step two is (2 mL to 2.1 mL):(0.3 mL to 0.5 mL):(4.9 mL to 5 mL). The other steps are the same as in Specific Implementation Methods One to Five.
[0043] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One through Six in that the cellulose-based membrane material used for food testing is used as a food freshness indicator. The other steps are the same as in Specific Implementation Methods One through Six.
[0044] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that: after the food freshness indicator is discarded, it is soaked in water at room temperature for a period of time, then filtered to recover the anthocyanin solution. Water is then added again, and the mixture is heated and stirred until the food freshness indicator is completely dissolved, and the nanocellulose solution is recovered. Other steps are the same as in Specific Implementation Methods One to Seven.
[0045] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that: after the food freshness indicator is discarded, 6 mg of the discarded food freshness indicator is added to 3 mL of water and soaked for 1 minute at room temperature, then filtered to recover the anthocyanin solution. Another 5 mL of water is added, and the mixture is heated to 40°C and stirred until the food freshness indicator is completely dissolved. The nanocellulose solution is then recovered. Other steps are the same as in Specific Implementation Methods One to Eight.
[0046] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One through Nine in that: the food freshness indicator is dissolved in deionized water to obtain a sample solution with a pH value of 3; then, by adding NaOH solution, sample solutions with pH values of 4, 5, 6, 7, 8, 9, 11, or 12 are obtained; the transmission spectrum curves of the sample solutions with pH values of 3, 4, 5, 6, 7, 8, 9, 11, or 12 are measured; the transmission spectrum of the solid film of the food freshness indicator under different environmental pH values is tested to obtain a standard curve; by comparing the transmission spectrum curve with the standard curve, the pH value corresponding to the food freshness indicator in use is obtained; the ammonia adsorption amount of the food freshness indicator is calculated according to Formula 1 and Formula 2.
[0047] pH<7: NH 3吸附 ={(0.001-10 -pH Formula 1;
[0048] pH>7:NH 3吸附 =[(0.001+10 14-pH Formula 2.
[0049] The other steps are the same as those in Specific Implementation Methods 1 to 9.
[0050] The beneficial effects of the present invention are verified using the following embodiments:
[0051] Example 1: A method for preparing a cellulose-based membrane material for food testing, specifically comprising the following steps:
[0052] I. Preparation of nanocellulose suspension:
[0053] ① Dilute concentrated sulfuric acid with a mass fraction of 98% to obtain a sulfuric acid solution with a mass fraction of 64%;
[0054] ② Mix 34g of cotton lint with 600mL of 64% sulfuric acid solution and hydrolyze for 1 hour at a stirring speed of 1850r / min and a temperature of 45℃. Then add 2800mL of deionized water to stop the hydrolysis reaction and obtain the reaction product. Let the reaction product stand for 10 hours to allow sedimentation. Pour off the supernatant and centrifuge the polymerized nanocellulose at the bottom of the tube at 6000r / min for 5 minutes. Pour off the supernatant and refill the centrifuge tube with deionized water to redisperse the nanocellulose at the bottom of the tube. Centrifuge again at 6000r / min for 5 minutes. Redisperse the centrifuged nanocellulose in 1200mL of deionized water for dialysis. Change the water every 3 hours until the solution is ready for dialysis. The pH of the deionized water was stabilized at 6-7. The nanocellulose solution was removed from the dialysis tube and uniformly weighted into centrifuge tubes. The solution was centrifuged at 11000 rpm for 20 minutes using a high-speed centrifuge. The supernatant was poured into a beaker to obtain a medium-grade nanocellulose solution, and the polymerized nanocellulose in the centrifuge tube was discarded. The medium-grade nanocellulose solution was then uniformly weighted into centrifuge tubes and centrifuged at 11000 rpm for 20 minutes using a high-speed centrifuge. The supernatant was poured into a beaker to obtain a high-grade nanocellulose solution. The high-grade nanocellulose solution was ultrasonically treated at 800W power in an ice-water bath for 270 seconds, and then concentrated in a 60℃ oven to obtain a nanocellulose suspension with a mass fraction of 1.17%.
[0055] II. Preparation of cellulose-based membrane materials:
[0056] 2.1 mL of anthocyanin solution with a concentration of 2 mg / mL and 0.5 mL of ethylene glycol were dissolved in 5 mL of nanocellulose suspension with a mass fraction of 1.17% to obtain a mixed solution. Under the conditions of 25℃ and 50% relative humidity, the mixed solution was placed on a flat table for evaporation, drying and self-assembly to obtain a cellulose-based membrane material for food detection, which is a food freshness indicator.
[0057] Figure 1 Macroscopic images of the cellulose-based membrane material for food testing prepared in Example 1 under different polarized light, where (a) is natural light, (b) is left-handed light, and (c) is right-handed light;
[0058] from Figure 1 It can be seen that different polarized light exhibits different color characteristics, as calculated... Figure 1 The preparation of the sample only requires 5.85 mg of cellulose nanocrystals, which effectively reduces the production cost of the sample.
[0059] Figure 2SEM images of amorphous nanocellulose films and cellulose-based membrane materials for food detection prepared in Example 1, wherein (a) is an amorphous nanocellulose film without chiral structure, and (b) is a cellulose-based membrane material for food detection prepared in Example 1 with chiral structure.
[0060] from Figure 2 As can be seen, the cellulose in the amorphous nanocellulose film is arranged randomly and irregularly. After forming the sample (the cellulose-based membrane material for food testing prepared in Example 1), it can be observed that the cellulose on the sample is arranged in a neat and orderly manner in a layered structure and forms a chiral nematic, which can reflect polarized light with a specific rotation direction, thereby producing a special circularly polarized structural color.
[0061] Figure 3 The visible light absorption spectra of the cellulose-based membrane material for food detection prepared in Example 1 under different environmental pH values are shown. Among them, the pH value of a is 3, the pH value of b is 4, the pH value of c is 7, the pH value of d is 9, and the pH value of e is 11.
[0062] from Figure 3 It can be seen that as the pH value of the environment increases, the main absorption peak of the sample (the cellulose-based membrane material for food detection prepared in Example 1) shifts from 520 nm to 590 nm, and the apparent color of the sample (the cellulose-based membrane material for food detection prepared in Example 1) also changes from red to yellow. This provides theoretical support for the detection of seafood freshness.
[0063] Figure 4 The morphological changes of the cellulose-based membrane material for food testing prepared in Example 1 under different humidity conditions are shown in the figure.
[0064] from Figure 4 It can be seen that the color of the sample (the cellulose-based membrane material for food testing prepared in Example 1) changed from blue under low humidity to red under high humidity.
[0065] Figure 5 Reflectance spectra of cellulose-based membrane materials for food testing prepared in Example 1 under different humidity conditions, wherein the humidity of 1 is 50%, the humidity of 2 is 70%, the humidity of 3 is 80%, the humidity of 4 is 90%, and the humidity of 5 is 100%.
[0066] from Figure 5 It can be seen that as humidity increases, the film exhibits a significant change in structural color, manifested as a red shift in the reflectance spectrum.
[0067] Figure 6The graph shows the spoilage of fresh shrimp under refrigerated conditions at 4°C and natural conditions at 25°C, using the cellulose-based membrane material prepared in Example 1 for food detection as a food freshness indicator, and the response of the food freshness indicator under the corresponding conditions.
[0068] from Figure 6 As can be seen, the spoilage of fresh shrimp in a refrigerated environment of 4℃ and a natural environment of 25℃ corresponds to the response of the smart label (food freshness indicator) under the corresponding conditions. As the fresh shrimp spoils, the color of the smart label changes from red to gray and then to orange. Moreover, the response sensitivity is high, and it can complete the freshness response in a timely manner at various temperatures (4℃-25℃) encountered in daily life.
[0069] The cellulose-based membrane material (food freshness indicator) prepared in Example 1 for food testing was dissolved in deionized water to obtain a sample solution with a pH of 3; then, by adding NaOH solution, sample solutions with pH values of 4, 5, 6, 7, 8, 9, 11, or 12 were obtained; the transmission spectrum curves of the sample solutions with pH values of 3, 4, 5, 6, 7, 8, 9, 11, or 12 were measured, see [see details]. Figure 7 As shown;
[0070] Figure 7 The standard curves of transmission spectra of the cellulose-based membrane material for food detection prepared in Example 1 as a food freshness indicator are shown in the figure. The pH value of a is 3, the pH value of b is 4, the pH value of c is 5, the pH value of d is 6, the pH value of e is 7, the pH value of f is 8, the pH value of g is 9, the pH value of h is 10, and the pH value of I is 11.
[0071] Perform a transmission spectroscopy test on the smart label (food freshness indicator) currently in use, and then compare it with... Figure 7 By comparison, the pH value of the smart label (food freshness indicator) in use can be determined, and the ammonia adsorption capacity of the food freshness indicator can be calculated according to Formula 1 and Formula 2.
[0072] pH<7: NH 3吸附 ={(0.001-10 -pH Formula 1;
[0073] pH>7:NH 3吸附 =[(0.001+10 14-pH Formula 2.
Claims
1. A method for preparing a cellulose-based membrane material for food testing, characterized in that... The preparation method is specifically carried out according to the following steps: I. Preparation of nanocellulose suspension: ① Dilute concentrated sulfuric acid with a mass fraction of 98% to obtain a sulfuric acid solution with a mass fraction of 62.5%~64%; ② Mix cotton lint with a sulfuric acid solution with a mass fraction of 62.5%~64%, carry out hydrolysis reaction under stirring, then add deionized water, and then centrifuge and dialyze to obtain a primary nanocellulose solution. ③ The primary nanocellulose solution is centrifuged multiple times to remove impurities, then treated with an ultrasonic pulverizer, and then concentrated in an oven at a temperature of 45℃~60℃ to obtain a nanocellulose suspension with a mass fraction of 1.17%~1.62%. II. Preparation of cellulose-based membrane materials: Anthocyanin solution and ethylene glycol were dissolved in a nanocellulose suspension with a mass fraction of 1.17%~1.62% to obtain a mixed solution. Under the conditions of 25℃ and 50% relative humidity, the mixed solution was placed on a flat table for evaporation, drying and self-assembly to obtain a cellulose-based membrane material for food testing.
2. The method for preparing a cellulose-based membrane material for food testing according to claim 1, characterized in that... The volume ratio of the cotton lint to the sulfuric acid solution with a mass fraction of 62.5%~64% in step 1② is 34g:600mL; the volume ratio of the sulfuric acid solution with a mass fraction of 62.5%~64% to deionized water in step 1② is 600:(2400~2800).
3. The method for preparing a cellulose-based membrane material for food testing according to claim 1, characterized in that... The stirring speed in step 1② is 1850 r / min to 2000 r / min; the hydrolysis reaction time in step 1② is 60 min to 70 min.
4. The method for preparing a cellulose-based membrane material for food testing according to claim 1, characterized in that... The ultrasonic pulverizer mentioned in step 1③ has a power of 800W; the processing time using the ultrasonic pulverizer in step 1③ is 270s~300s.
5. The method for preparing a cellulose-based membrane material for food testing according to claim 1, characterized in that... The concentration of the anthocyanin solution mentioned in step two is 2 mg / mL to 2.1 mg / mL.
6. The method for preparing a cellulose-based membrane material for food testing according to claim 1, characterized in that... The volume ratio of the anthocyanin solution, ethylene glycol, and nanocellulose suspension with a mass fraction of 1.17%~1.62% in step two is (2mL~2.1mL):(0.3mL~0.5mL):(4.9mL~5mL).
7. The application of the cellulose-based membrane material for food testing prepared by the method described in claim 1, characterized in that... Cellulose-based membrane materials for food testing are used as indicators of food freshness.
8. The application of the cellulose-based membrane material for food testing according to claim 7, characterized in that... After the food freshness indicator is discarded, it is soaked in water at room temperature for a period of time, then filtered to recover the anthocyanin solution. Water is then added again, the temperature is raised and stirred until the food freshness indicator is completely dissolved, and the nanocellulose solution is recovered.
9. The application of the cellulose-based membrane material for food testing according to claim 8, characterized in that... After the food freshness indicator is discarded, 6 mg of the discarded food freshness indicator is added to 3 mL of water and soaked for 1 minute at room temperature. Then it is filtered to recover the anthocyanin solution. 5 mL of water is added, the temperature is raised to 40°C and stirred until the food freshness indicator is completely dissolved and the nanocellulose solution is recovered.
10. The application of the cellulose-based membrane material for food testing according to claim 8, characterized in that... The food freshness indicator was dissolved in deionized water to obtain a sample solution with a pH of 3. Then, by adding NaOH solution, sample solutions with pH values of 4, 5, 6, 7, 8, 9, 11, or 12 were obtained. The transmission spectra of the sample solutions with pH values of 3, 4, 5, 6, 7, 8, 9, 11, or 12 were measured. The transmission spectra of the solid film of the food freshness indicator under different environmental pH values were tested to obtain a standard curve. By comparing the transmission spectra with the standard curve, the pH value corresponding to the food freshness indicator in use was obtained. The ammonia adsorption capacity of the food freshness indicator was calculated according to Formulas 1 and 2. pH<7: NH 3吸附 ={(0.001-10 -pH Formula 1; pH>7: NH 3吸附 =[(0.001+10 14-pH Formula 2.
Citation Information
Patent Citations
Procedure for displaying the carbon dioxide content cut climatic fruit or vegetables.
CH712036A2
Food freshness indicator using cellulose nanocrystal-silver nanoparticle film and manufacturing method thereof
KR1020180138096A