Acylated chitosan oligosaccharide for fresh keeping of fresh strawberries
Acylated chitosan oligosaccharide was prepared by modifying chitosan oligosaccharide with lauroyl chloride, which solved the problem of perishable fresh strawberry fruit, achieved efficient preservation effect, extended shelf life and reduced costs.
Patent Information
- Application Number
- CN202510750685.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-06
- Publication Date
- 2025-09-19
AI Technical Summary
Fresh strawberries are prone to rot during post-harvest preservation. The antibacterial activity of chitosan oligosaccharides in existing technologies is weak, making it difficult to effectively extend their shelf life.
Chitosan oligosaccharide was modified with lauroyl chloride to prepare acylated chitosan oligosaccharide, which was used as a fresh-keeping agent for strawberry fruit, significantly improving its anti-corruption effect.
Acylated chitosan oligosaccharide significantly reduces the spoilage rate of strawberries, extends the shelf life, reduces preservation costs, and maintains the freshness and color of strawberries.
Smart Images
Figure CN120665215A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to an acylated chitosan oligosaccharide derivative, in particular to an acylated chitosan oligosaccharide for preserving fresh strawberries. Background Art
[0002] Strawberries are berries with high respiratory metabolism, thin skin, and fragile tissue. They are highly susceptible to mechanical damage during harvesting and transportation, which can lead to pathogenic bacteria infection and high rates of fruit rot. According to statistics, strawberries typically only last 1-3 days at room temperature after harvest. Even under refrigeration, their shelf life can only be extended to 3-5 days. Therefore, it is necessary to develop efficient and convenient methods for preserving fresh strawberries.
[0003] Chitosan oligosaccharides (COS) are derived from chitosan through acid hydrolysis, oxidation, and physical degradation. They are the only positively charged alkaline amino oligosaccharides found in nature, with a degree of polymerization (DP) of 2-50. Compared to chitosan, chitosan oligosaccharides have a lower molecular weight, better water solubility, and are non-toxic. Studies have shown that chitosan oligosaccharides have antibacterial activity, inhibiting the growth and reproduction of bacteria and fungi, but the activity is generally weak. Chitosan oligosaccharides have a unique structure, containing active amino and hydroxyl groups within the molecule, making them susceptible to chemical reactions. The amino group at position C2 and the hydroxyl groups at positions C3 and C6 are active groups. Modification of these active sites with other groups can produce different chitosan oligosaccharide derivatives, thereby altering the bioactivity of chitosan oligosaccharides.
[0004] There is currently no report on chemically modifying chitosan oligosaccharides with lauroyl chloride to prepare acylated chitosan oligosaccharides (acylated chitosan oligosaccharide derivatives) to significantly improve the anti-corruption effect of fruits and thus use them as fresh-keeping agents for strawberries. Summary of the Invention
[0005] The present invention aims to solve the above-mentioned technical problems existing in the prior art and provides an acylated chitosan oligosaccharide for preserving fresh strawberries.
[0006] The technical solution of the present invention is: an acylated chitosan oligosaccharide for preserving fresh strawberry fruit, the structural formula of which is as follows: ; The n=2-50 is prepared in the following steps: Step 1. Weigh a certain amount of chitosan oligosaccharide, dissolve the chitosan oligosaccharide in a methanesulfonic acid solution in an ice-water bath, and stir evenly to generate a chitosan oligosaccharide methanesulfonate solution; Step 2. Add sodium hydroxide solution to the chitosan oligosaccharide methanesulfonate solution and stir evenly. Then, add lauroyl chloride dropwise to the solution at a molar ratio of chitosan oligosaccharide to lauroyl chloride of 1:20 and continue the reaction for 3 h. Step 3. Add ammonia water to react until a suspension is obtained, wash with anhydrous ethanol and acetone in sequence, evaporate the solvent using a rotary evaporator, and freeze-dry to obtain acylated chitosan oligosaccharide.
[0007] The preferred acylated chitosan oligosaccharide for preserving fresh strawberry fruit is an aqueous solution of acylated chitosan oligosaccharide with a concentration of 1.0-20 mg / ml.
[0008] The present invention uses lauroyl chloride to modify the hydroxyl groups of chitosan oligosaccharide to synthesize acylated chitosan oligosaccharide. Compared with chitosan oligosaccharide, the spoilage rate of strawberries treated with acylated chitosan oligosaccharide is significantly reduced and the usage amount is only 1 / 4 of that of chitosan oligosaccharide. The acylated chitosan oligosaccharide can be used as a fresh strawberry preservative. Compared with chitosan oligosaccharide, the shelf life of fresh strawberries is extended and the preservation cost is reduced. BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Figure 1 It is the infrared spectrum of acylated chitosan oligosaccharide and chitosan oligosaccharide according to the embodiment of the present invention.
[0010] Figure 2 1 is an X-ray diffraction diagram of acylated chitosan oligosaccharide and chitosan oligosaccharide according to an embodiment of the present invention.
[0011] Figure 3 It is the nuclear magnetic resonance hydrogen spectrum of the acylated chitosan oligosaccharide and chitosan oligosaccharide of the embodiment of the present invention.
[0012] Figure 4 This is a diagram showing the preservation effects of acylated chitosan oligosaccharide and strawberries treated with chitosan oligosaccharide according to an embodiment of the present invention.
[0013] Figure 5 Schematic diagram of the weight loss rate of acylated chitosan oligosaccharide and chitosan oligosaccharide-treated strawberries according to an embodiment of the present invention.
[0014] Figure 6 This is a graph showing the color saturation changes of strawberries treated with acylated chitosan oligosaccharides and chitosan oligosaccharides according to an embodiment of the present invention.
[0015] Figure 7 This is a graph showing the brightness changes of strawberries treated with acylated chitosan oligosaccharide and chitosan oligosaccharide according to an embodiment of the present invention. DETAILED DESCRIPTION
[0016] An acylated chitosan oligosaccharide for preserving fresh strawberries has the following structural formula: ; The n=2-50 is prepared in the following steps: Step 1. Weigh 4.05 g of chitosan oligosaccharide and dissolve it in 7.5 g of Stir in methanesulfonic acid solution for 2 h to generate chitosan oligosaccharide methanesulfonate solution; Step 2. Add 40% (w / v) NaOH solution to the chitosan oligosaccharide methanesulfonate solution and stir for 3 h. Then, add lauroyl chloride dropwise to the solution at a molar ratio of chitosan oligosaccharide to lauroyl chloride of 1:20 and continue the reaction for 3 h. Step 3. Add ammonia water to react until a suspension is obtained. Wash with anhydrous ethanol and acetone three times in sequence. Evaporate the solvent using a rotary evaporator and freeze-dry to obtain acylated chitosan oligosaccharide (COS-C12).
[0017] The raw materials used in the examples are all commercially available products, wherein the chitosan oligosaccharide has a polymerization degree of 2-50 and a deacetylation degree greater than 90%; the molecular formula of lauroyl chloride is C 12 H 23 ClO, molecular weight is 218.76.
[0018] The reaction formula is as follows: ; experiment: 1. Chitosan oligosaccharide raw materials used in the embodiments of the present invention and infrared spectrum analysis of the obtained products Chitosan oligosaccharide (COS) used in the embodiment of the present invention and the prepared acylated chitosan oligosaccharide (COS-C12) were mixed and ground with potassium bromide at a mass ratio of 1:100, and infrared spectra were measured by potassium bromide tablet method with a scanning range of 4000-400 cm -1 , the number of scans was 72, and the resolution was 4 cm -1 , infrared spectrum such as Figure 1 As shown. Figure 1 It can be seen that in the infrared spectrum of chitosan oligosaccharide, 3400 cm -1 The peaks on the left and right are the superimposed absorption peaks of hydrogen bonds, NH and OH stretching vibrations in chitosan oligosaccharide molecules, which are characteristic peaks of COS, proving the existence of hydrogen bonds in COS; 1080 cm -1 It belongs to the stretching vibration of the sugar ring skeleton COC in COS. Compared with COS, the OH stretching vibration of acylated chitosan oligosaccharide is at 3400 cm -1 The peak at 2927.9 cm -1 A new set of absorption peaks appeared at 1564.2 cm -1 and 1435.0 cm -1 The formation of carbonyl (C=O) was confirmed. These data indicate that the present invention successfully synthesized acylated chitosan oligosaccharide (COS-C12).
[0019] 2. XRD analysis of the raw chitosan oligosaccharide used in the examples of the present invention and the obtained acylated chitosan oligosaccharide (COS-C12) Chitosan oligosaccharide (COS) and acylated chitosan oligosaccharide (COS-C12) used in the embodiment of the present invention were ground separately, added with anhydrous ethanol and spread on a silicon plate. After the anhydrous ethanol evaporated, XRD analysis was performed on the samples. The scanning conditions were Cu target, scanning temperature 25°C, scanning speed 4° / min, scanning range 5-80°, and the X-ray diffraction pattern was as follows: Figure 2 As shown. Figure 2 It can be seen that the characteristic diffraction peak of COS was found at 21.5°, which is related to the crystal morphology of COS. The molecular structure of COS is mainly maintained by intramolecular hydrogen bonds and intermolecular hydrogen bonds. Compared with COS, acylated chitosan oligosaccharide (COS-C12) showed new diffraction absorption peaks at 31.5°, 45° and 56°, respectively, and the maximum peak shifted to 31.5°, indicating that the addition of lauroyl chloride changed the crystal form of chitosan oligosaccharide.
[0020] 3. Nuclear Magnetic Resonance Proton Spectrum Analysis of the Raw Chitosan Oligosaccharide and the Acylated Chitosan Oligosaccharide (COS-C12) Used in the Examples of the Present Invention Weigh a small amount of chitosan oligosaccharide (COS) and acylated chitosan oligosaccharide (COS-C12) and transfer them to the NMR tube. Use a pipette to transfer DMSO-d6 to the NMR tube. After shaking until fully dissolved, perform hydrogen spectrum measurement. The NMR hydrogen spectrum is shown in the figure below. Figure 3 As shown. Figure 3 As can be seen in the figure, the absorption peak at δ = 1.91 ppm is the chemical shift of the methyl group on the chitosan oligosaccharide that has not been completely deacetylated, while δ = 3.0-3.75 ppm is the chemical shift of the hydrogen atoms on the glucosamine and N-acetylglucosamine residues on the COS sugar ring. The solvent (DMSO) absorption peak is at 2.51 ppm. Compared to COS, the triplet peak of methyl groups at 0.86 ppm is the chemical shift of the methyl group at the end of the acyl chain and is a characteristic peak of COS acylated derivatives. NMR results further demonstrate that lauroyl chloride has been successfully grafted onto COS.
[0021] 4. Fruit preservation experiment of the raw material chitosan oligosaccharide used in the examples of the present invention and the obtained acylated chitosan oligosaccharide (COS-C12) Strawberries of uniform size, maturity, and no mechanical damage were selected, washed with deionized water, and divided into three groups: a control group, a COS group, and a COS-C12 group. They were then immersed in deionized water, a 20 mg / ml COS solution, and a 5 mg / ml COS-C12 solution for 5 minutes, respectively, and then placed on trays to dry.
[0022] 1. Observe the rottenness of strawberries in each group under normal temperature conditions. The preservation effect of strawberries is as follows: Figure 4 shown.
[0023] The results showed that on the first day, all strawberries in the treatment group were very fresh, with bright red, shiny skins. Over time, the strawberries in the control group began to grow mold on the second day, and all were moldy on the sixth day. The strawberries treated with COS-C12 showed almost no mold formation or obvious signs of decay, with only slight mold growth appearing on the sixth day. This demonstrated comparable or even superior efficacy to a four-fold concentration of COS, indicating that COS-C12 can be used to preserve fresh strawberries at a lower dosage than COS.
[0024] 2. Weight loss rate determination The strawberries were weighed every two days and the weight loss rate was calculated according to the following formula: Weight loss rate (%) = (W0-W1) / W0×100 Where W0 is the initial storage sample weight; W1 is the weight of the storage sample on the day of sampling.
[0025] Schematic diagram of strawberry weight loss rate Figure 5 As shown. Figure 5 It can be seen that as the storage time increases, the weight loss rate of strawberries in each group also increases. Compared with the control group, COS has a certain improvement effect on the weight loss of strawberries, and the weight loss rate of strawberries in the COS-C12 group is significantly reduced, indicating that COS-C12 can slow down the respiration and transpiration of fruits, thereby maintaining the freshness of strawberries.
[0026] 3. Measurement of color saturation and brightness of strawberries The color difference of the treated strawberries was measured on days 0, 2, 4, and 6 to observe the color saturation and brightness of the strawberries. The results are as follows: Figure 6 and 7 shown.
[0027] Color saturation indicates color purity. The higher the value, the higher the color purity and the brighter the color. The higher the brightness, the fresher the strawberry. Figure 6 and 7 It can be seen that as the storage time increases, the color saturation and brightness of the strawberry fruit decrease. After 6 days, the color saturation of the control group is the smallest, indicating that the strawberry fruit has aged; the color saturation and brightness of the strawberries in the COS-C12 group are the largest, indicating that the fruit is freshest, which is consistent with the apparent conclusion.
Claims
1. An acylated chitosan oligosaccharide for preserving fresh strawberry fruit, characterized in that The structural formula is as follows: ； The n=2-50 is prepared in the following steps: Step 1. Weigh a certain amount of chitosan oligosaccharide, dissolve the chitosan oligosaccharide in a methanesulfonic acid solution in an ice-water bath, and stir evenly to generate a chitosan oligosaccharide methanesulfonate solution; Step 2. Add sodium hydroxide solution to the chitosan oligosaccharide methanesulfonate solution and stir evenly. Then, add lauroyl chloride dropwise to the solution at a molar ratio of chitosan oligosaccharide to lauroyl chloride of 1:20 and react for 3 h. Step 3. Add ammonia water to react until a suspension is obtained, wash with anhydrous ethanol and acetone in sequence, evaporate the solvent using a rotary evaporator, and freeze-dry to obtain acylated chitosan oligosaccharide.
2. The acylated chitosan oligosaccharide for preserving fresh strawberry fruit according to claim 1, characterized in that It is an aqueous solution of acylated chitosan oligosaccharide with a concentration of 1.0-20 mg / ml.