Preparation method of high-sensitivity anthocyanin intelligent indicating label
By adding chitosan quaternary ammonium salt to the film-forming matrix and combining it with the pH responsiveness of anthocyanins, a highly sensitive smart indicator label was prepared, which solved the problems of insufficient safety and sensitivity of synthetic indicators and realized the visual monitoring of food quality.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANDONG ACADEMY OF AGRICULTURAL SCIENCES
- Filing Date
- 2023-06-29
- Publication Date
- 2026-06-23
AI Technical Summary
The preparation of sensitive materials for existing smart food labels mainly relies on synthetic indicators, which poses safety concerns. Furthermore, the sensitivity of products on the market is limited, making it difficult to effectively distinguish changes in food quality with the naked eye.
A highly sensitive smart indicator tag was prepared using a component structure of anthocyanin-chitosan quaternary ammonium salt-sodium carboxymethyl cellulose. By adding chitosan quaternary ammonium salt to the film-forming matrix and combining it with the pH responsiveness of anthocyanin, a significant color change was achieved.
Within the pH range of 2 to 8, especially within the pH range of 4 to 8, the prepared smart indicator labels can significantly distinguish changes in food quality, and the visible color changes reflect the freshness of the food.
Smart Images
Figure CN116813988B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing a highly sensitive anthocyanin smart indicator label, belonging to the field of smart labels. Background Technology
[0002] As consumers increasingly demand food safety and freshness, their focus on food packaging has shifted from traditional, singular protective requirements to diversified functions. Among these, real-time feedback on changes in food quality has become a new function sought after in food packaging. Smart food labels are a type of label that can reflect food quality in real time through color changes, making food quality visible. Smart food labels are generally based on color changes in sensitive materials caused by alterations in certain properties of the food. During storage, food gradually spoils, producing volatile nitrogenous and ammonia metabolites. These substances accumulate inside the packaging, causing a color change in the pH-sensitive material on the packaging surface. Changes in the color of the pH-sensitive material are used to monitor changes in the quality of the food inside the packaging.
[0003] Currently, the preparation of sensitive materials for smart labels mainly relies on the addition of color indicators, many of which are synthetic, such as bromocresol purple and bromothymol blue. However, the safety of synthetic indicators has been questioned, making them unsuitable for food smart label applications. Anthocyanins are a class of natural water-soluble pigments commonly found in fruits, vegetables, flowers, and grains, also known as anthocyanins. Their basic structure is a 2-phenylbenzopyran cation, belonging to the flavonoid class of compounds. Due to the highly conjugated molecular system within the anthocyanin molecule, its structure transforms under different acidic and alkaline conditions, resulting in different color changes. During food spoilage, pH changes, and anthocyanins are gas-sensitive materials that can detect the odor of food spoilage, providing feedback on food quality by monitoring and indicating changes in the internal environment of the packaging.
[0004] Currently, there have been studies that have added carboxymethyl cellulose to anthocyanins or added chitosan to anthocyanins. However, both carboxymethyl cellulose and chitosan act as film-forming agents, but the sensitivity of commercially available products is limited, and they cannot be effectively distinguished by the naked eye. Summary of the Invention
[0005] To solve the above problems, the inventors added chitosan quaternary ammonium salt to the film-forming matrix and used an anthocyanin-chitosan quaternary ammonium salt-sodium carboxymethyl cellulose component structure to prepare a highly sensitive anthocyanin smart indicator tag. The tag has very high sensitivity and shows obvious differences in the pH range of 2 to 8, especially in the pH range of 4 to 8.
[0006] The first objective of this invention is to provide a method for preparing a highly sensitive anthocyanin smart indicator label, comprising the following steps:
[0007] (1) Preparation of anthocyanin stock solution;
[0008] (2) Prepare sodium carboxymethyl cellulose solution and chitosan quaternary ammonium salt solution respectively, and mix the two to obtain film-forming matrix;
[0009] (3) Mix the anthocyanin stock solution and the film-forming matrix to obtain an anthocyanin mixture;
[0010] (4) After removing air bubbles from the mixture by ultrasound, the mixture is cast into an acrylic mold and dried to obtain an indicator label.
[0011] In one embodiment, the preparation of anthocyanin stock solution in step (1) involves dissolving anthocyanins in a hydrochloric acid solution; optionally, hydrochloric acid with pH 2.
[0012] In one embodiment, step (2) involves uniformly mixing chitosan quaternary ammonium salt solution and sodium carboxymethyl cellulose solution in a 1:1 ratio to obtain a film-forming matrix.
[0013] In one embodiment, the final concentration of chitosan quaternary ammonium salt in the film-forming matrix in step (2) is 0.1-0.5 mg / mL.
[0014] In one embodiment, before mixing in step (2), the concentration of the chitosan quaternary ammonium salt solution is 0.6 mg / mL, and the concentration of the sodium carboxymethyl cellulose solution is 3% (w / w, unless otherwise specified, the percentages used in this invention refer to mass percentages).
[0015] In one embodiment, step (3) involves mixing anthocyanin stock solution and film-forming matrix to obtain an anthocyanin mixture with a final anthocyanin concentration of 0.3 mg / mL to 0.5 mg / mL, adding glycerol at a final concentration of 0.5% to 1.5%, and finally adjusting the pH of the mixture to 3 to 5 with hydrochloric acid solution.
[0016] In one embodiment, the drying conditions for step (4) are to place the product in an oven at 40°C for 24 hours.
[0017] The second objective of this invention is to provide a highly sensitive anthocyanin smart indicator label, which is prepared by the method described above.
[0018] The third objective of this invention is to provide a method for monitoring food quality using a highly sensitive anthocyanin smart indicator label, comprising the steps of: affixing a highly sensitive anthocyanin smart indicator label to a package containing food and sealing the package; the label is placed in a transparent area of the package; the package is a bag or a box.
[0019] The fourth objective of this invention is to provide an application of a highly sensitive anthocyanin smart indicator label in the visual detection of food freshness.
[0020] In one embodiment, the food product may be meat products, dairy products, eggs, or grains.
[0021] Advantages and effects of the present invention:
[0022] (1) The preparation method of the present invention is simple and easy to scale up.
[0023] (2) The present invention prepares a highly sensitive anthocyanin smart indicator tag with very high sensitivity and obvious difference in the pH range of 2 to 8, especially in the pH range of 4 to 8.
[0024] (3) The intelligent indicator label prepared by the present invention can be used for visual detection of food freshness. The freshness of food can be judged by the color change that is visible to the naked eye. Attached Figure Description
[0025] Figure 1 The image shows the effect of the anthocyanin smart indicator label prepared in Example 1.
[0026] Figure 2 The image shows the effect of the anthocyanin smart indicator label prepared in Example 2.
[0027] Figure 3 The image shows the effect of the anthocyanin smart indicator label prepared in Example 3.
[0028] Figure 4 The image shows the effect of anthocyanin smart indicator tags prepared with different final concentrations of chitosan quaternary ammonium salt solution in the film-forming matrix; where a corresponds to a final concentration of chitosan quaternary ammonium salt solution of 0.1 mg / mL, b corresponds to 0.3 mg / mL, and c corresponds to 0.5 mg / mL.
[0029] Figure 5 The image shows the effect of the anthocyanin smart indicator label prepared in Comparative Example 1.
[0030] Figure 6 The image shows the effect of the anthocyanin smart indicator tags prepared with different final anthocyanin concentrations in Example 1; where a corresponds to a final anthocyanin concentration of 0.1 mg / mL, b corresponds to a final anthocyanin concentration of 0.3 mg / mL, and c corresponds to a final anthocyanin concentration of 0.5 mg / mL.
[0031] Figure 7 The image shows the effect of the anthocyanin smart indicator label prepared in Comparative Example 2. Detailed Implementation
[0032] Material:
[0033] Anthocyanins, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., product number: C302404.
[0034] Chitosan quaternary ammonium salt, purchased from Shanghai Maclean Biochemical Technology Co., Ltd., item number: 850126.
[0035] Example 1: A method for preparing a high-sensitivity anthocyanin smart indicator tag
[0036] (1) Dissolve anthocyanins in a hydrochloric acid solution at pH 2 to obtain a 10 mg / mL anthocyanin stock solution.
[0037] (2) Prepare 3% sodium carboxymethyl cellulose solution and 0.6 mg / mL chitosan quaternary ammonium salt solution respectively, and mix them evenly at a ratio of 1:1 to obtain the film-forming matrix; the final concentration of chitosan quaternary ammonium salt solution in the film-forming matrix is 0.3 mg / mL.
[0038] (3) Mix the anthocyanin stock solution and the film-forming matrix in proportion to obtain an anthocyanin mixture with a final concentration of 0.3 mg / mL. Add glycerol at a final concentration of 1%, and finally adjust the pH of the mixture to 4.5 with 1 mol / L hydrochloric acid solution.
[0039] (4) After removing air bubbles from the mixture by ultrasound, the mixture is cast into an acrylic mold and placed in a 40°C oven to dry for 24 hours to obtain an indicator label.
[0040] like Figure 1 As shown, the prepared anthocyanin smart indicator label was evaluated for its effectiveness (liquids of different standard pH were added to the indicator label and observed after standing). The results showed that it could be clearly distinguished by the naked eye in the pH range of 2-8, especially in the pH range of 4-8, indicating that the anthocyanin smart indicator label prepared in this embodiment has a very good effect.
[0041] Example 2: A method for preparing a high-sensitivity anthocyanin smart indicator tag
[0042] (1) Dissolve anthocyanins in a hydrochloric acid solution at pH 2 to obtain a 10 mg / mL anthocyanin stock solution.
[0043] (2) Prepare 3% sodium carboxymethyl cellulose solution and 0.6 mg / mL chitosan quaternary ammonium salt solution respectively, and mix them evenly in a 1:1 ratio to obtain the film-forming matrix.
[0044] (3) Mix the anthocyanin stock solution and the film-forming matrix to obtain an anthocyanin mixture with a final anthocyanin concentration of 0.4 mg / mL, add glycerol at a final concentration of 0.5%, and finally adjust the pH of the mixture to 4 with 1 mol / L hydrochloric acid solution.
[0045] (4) After removing air bubbles from the mixture by ultrasound, the mixture is cast into an acrylic mold and placed in a 40°C oven to dry for 24 hours to obtain an indicator label.
[0046] The prepared anthocyanin smart indicator label was evaluated for effectiveness, and the results are as follows: Figure 2 As shown, the results were similar to those of Example 1, with a clear visual distinction in the pH range of 2-8, especially in the pH range of 4-8.
[0047] Example 3: A method for preparing a high-sensitivity anthocyanin smart indicator tag
[0048] (1) Dissolve anthocyanins in a hydrochloric acid solution at pH 2 to obtain a 10 mg / mL anthocyanin stock solution.
[0049] (2) Prepare 3% sodium carboxymethyl cellulose solution and 0.6 mg / mL chitosan quaternary ammonium salt solution respectively, and mix them evenly in a 1:1 ratio to obtain the film-forming matrix.
[0050] (3) Mix the anthocyanin stock solution and the film-forming matrix to obtain an anthocyanin mixture with a final anthocyanin concentration of 0.5 mg / mL, add glycerol at a final concentration of 1.5%, and finally adjust the pH of the mixture to 3.5 with 1 mol / L hydrochloric acid solution.
[0051] (4) After removing air bubbles from the mixture by ultrasound, the mixture is cast into an acrylic mold and placed in a 40°C oven to dry for 24 hours to obtain an indicator label.
[0052] The prepared anthocyanin smart indicator label was evaluated for effectiveness, and the results are as follows: Figure 3 As shown, the results were similar to those of Example 1, with a clear visual distinction in the pH range of 2-8, especially in the pH range of 4-8.
[0053] Example 4: Anthocyanin smart indicator tags prepared with different final concentrations of chitosan quaternary ammonium salt solutions in the film-forming matrix
[0054] (1) Dissolve anthocyanins in a hydrochloric acid solution at pH 2 to obtain a 10 mg / mL anthocyanin stock solution.
[0055] (2) Prepare 3% sodium carboxymethyl cellulose solution and chitosan quaternary ammonium salt solution of different concentrations respectively, and mix them evenly at a ratio of 1:1 to obtain film-forming matrix; the final concentrations of chitosan quaternary ammonium salt solution in film-forming matrix are 0.1 mg / mL, 0.3 mg / mL (i.e. the concentration in Example 1), and 0.5 mg / mL respectively.
[0056] (3) Mix the anthocyanin stock solution and the film-forming matrix in proportion to obtain an anthocyanin mixture with a final concentration of 0.3 mg / mL. Add glycerol at a final concentration of 1%, and finally adjust the pH of the mixture to 4.5 with 1 mol / L hydrochloric acid solution.
[0057] (4) After removing air bubbles from the mixture by ultrasound, the mixture is cast into an acrylic mold and placed in a 40°C oven to dry for 24 hours to obtain an indicator label.
[0058] The results are as follows Figure 4 As shown, the prepared anthocyanin smart indicator label was found to be very effective through effect evaluation, and it can make obvious distinctions within the pH range of 2-8.
[0059] Comparative Example 1: A method for preparing an anthocyanin smart indicator label
[0060] Compared to Example 1, chitosan quaternary ammonium salt was not added, specifically:
[0061] (1) Dissolve anthocyanins in a hydrochloric acid solution at pH 2 to obtain a 10 mg / mL anthocyanin stock solution.
[0062] (2) Prepare a 3% sodium carboxymethyl cellulose solution to obtain a film-forming matrix.
[0063] (3) Mix the anthocyanin stock solution and the film-forming matrix to obtain an anthocyanin mixture with a final anthocyanin concentration of 0.3 mg / mL, add glycerol at a final concentration of 1%, and finally adjust the pH of the mixture to 4.5 with 1 mol / L hydrochloric acid solution.
[0064] (4) After removing air bubbles from the mixture by ultrasound, the mixture is cast into an acrylic mold and placed in a 40°C oven to dry for 24 hours to obtain an indicator label.
[0065] like Figure 5 As shown, the prepared anthocyanin smart indicator label was evaluated for effectiveness. The results showed that the indicator label could not provide effective indication and it was difficult to distinguish different pH levels with the naked eye.
[0066] Meanwhile, the inventors used the same method as in this embodiment to compare the indicator labels obtained with different final anthocyanin concentrations and their effects, and the results are as follows: Figure 6 As shown in the figure. The results indicate that, without the addition of chitosan quaternary ammonium salt solution, it is impossible to clearly distinguish between different pH values.
[0067] Comparative Example 2: A method for preparing an anthocyanin smart indicator label
[0068] Compared to Example 1, the chitosan quaternary ammonium salt was replaced with chitosan, specifically:
[0069] (1) Dissolve anthocyanins in a hydrochloric acid solution at pH 2 to obtain a 10 mg / mL anthocyanin stock solution.
[0070] (2) Prepare a 3% sodium carboxymethyl cellulose solution and a 0.6 mg / mL chitosan solution, and mix them evenly in a 1:1 ratio to obtain a film-forming matrix.
[0071] (3) Mix the anthocyanin stock solution and the film-forming matrix to obtain an anthocyanin mixture with a final anthocyanin concentration of 0.3 mg / mL, add glycerol at a final concentration of 1%, and finally adjust the pH of the mixture to 4.5 with 1 mol / L hydrochloric acid solution.
[0072] (4) After removing air bubbles from the mixture by ultrasound, the mixture is cast into an acrylic mold and placed in a 40°C oven to dry for 24 hours to obtain an indicator label.
[0073] like Figure 7 As shown, the indicator labels prepared using chitosan are not clearly distinguishable to the naked eye.
[0074] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.
Claims
1. The application of a high-sensitivity anthocyanin smart indicator label in the visual detection of food freshness, characterized in that, The preparation method of the high-sensitivity anthocyanin smart indicator tag includes the following steps: (1) Preparation of anthocyanin stock solution; Anthocyanins were dissolved in hydrochloric acid solution at pH 2 to obtain an anthocyanin stock solution of 10 mg / mL. (2) Prepare a 3% sodium carboxymethyl cellulose solution and a 0.6 mg / mL chitosan quaternary ammonium salt solution respectively, and mix the two to obtain a film-forming matrix; Among them, chitosan quaternary ammonium salt was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., item number: 850126; The mixing ratio of chitosan quaternary ammonium salt solution and sodium carboxymethyl cellulose solution is 1:1; The final concentration of chitosan quaternary ammonium salt is 0.1-0.5 mg / mL; (3) Mix the anthocyanin stock solution and the film-forming matrix to obtain an anthocyanin mixture with a final anthocyanin concentration of 0.3 mg / mL to 0.5 mg / mL, add glycerol at a final concentration of 0.5% to 1.5%, and finally adjust the pH of the mixture to 3 to 5 with hydrochloric acid solution; (4) After removing air bubbles from the mixture by ultrasound, the mixture is cast into an acrylic mold and dried to obtain a high-sensitivity anthocyanin smart indicator label.
2. The application according to claim 1, characterized in that, The food products mentioned are meat products, dairy products, eggs, and grains.
3. A method for monitoring food quality, characterized in that, A high-sensitivity anthocyanin smart indicator tag was adopted; the preparation method of the high-sensitivity anthocyanin smart indicator tag includes the following steps: (1) Preparation of anthocyanin stock solution; Anthocyanins were dissolved in a hydrochloric acid solution with a pH of 2 to obtain anthocyanin stock solution; (2) Prepare a 3% sodium carboxymethyl cellulose solution and a 0.6 mg / mL chitosan quaternary ammonium salt solution respectively, and mix the two to obtain a film-forming matrix; Among them, chitosan quaternary ammonium salt was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., item number: 850126; The mixing ratio of chitosan quaternary ammonium salt solution and sodium carboxymethyl cellulose solution is 1:1; The final concentration of chitosan quaternary ammonium salt is 0.1-0.5 mg / mL; (3) Mix the anthocyanin stock solution and the film-forming matrix to obtain an anthocyanin mixture with a final anthocyanin concentration of 0.3 mg / mL to 0.5 mg / mL, add glycerol at a final concentration of 0.5% to 1.5%, and finally adjust the pH of the mixture to 3 to 5 with hydrochloric acid solution; (4) After removing air bubbles from the mixture by ultrasound, the mixture is cast into an acrylic mold and dried to obtain a high-sensitivity anthocyanin smart indicator label.
4. The method according to claim 3, characterized in that, Place the highly sensitive anthocyanin smart indicator label inside the food packaging and seal the packaging.
5. The method according to claim 4, characterized in that, The sticker is placed on the transparent part of the packaging.
6. The method according to claim 5, characterized in that, The packaging is in bags or boxes.