A durian anti-cracking preservative based on fucoidan and a preparation method and application thereof

Abstract

This invention discloses a durian anti-cracking preservative based on fucoidan oligosaccharides, its preparation method, and its application. The preservative is characterized by being composed of the following raw materials in parts by weight: 3-8 parts fucoidan oligosaccharides, 2-5 parts sodium caseinate, 0.5-2 parts guar gum, 100-200 parts nano-curcumin emulsion, 1-3 parts glycerol, and 300-500 parts water. The preparation method includes the following steps: mixing curcumin, medium-chain triglycerides, Tween-80, and sodium caseinate solution under high-speed shearing to obtain a nano-curcumin emulsion; dissolving fucoidan oligosaccharides and glycerol in water and stirring until completely dissolved, then adding sodium caseinate and guar gum and stirring to obtain a fucoidan oligosaccharide composite membrane solution; finally, adding the nano-curcumin emulsion to the fucoidan oligosaccharide composite membrane solution, stirring, and allowing it to stand to remove bubbles, thus obtaining the durian anti-cracking preservative based on fucoidan oligosaccharides. The advantages are that it can prevent durian weight loss, delay physiological cracking, and improve the mechanical properties of the protective film.

Description

Technical Field

[0001] This invention belongs to the field of postharvest preservation technology for fruits, and in particular relates to a durian anti-cracking preservative based on brown algae oligosaccharides, its preparation method and application. Background Technology

[0002] Durian fruits exhibit vigorous post-harvest physiological activity, making them prone to shell cracking due to water evaporation and ethylene release. This leads to exposed flesh, quality deterioration, and microbial contamination, resulting in significant economic losses. Therefore, preventing durian cracking is a core challenge in post-harvest preservation. Currently, technologies for durian preservation mainly include physical temperature and humidity control storage, chemical preservative treatment, and edible coatings. Among these, edible coatings have attracted attention due to their ability to form selective barriers and load functional components. For example, patent CN112425646A discloses a preservative primarily composed of chitosan and trehalose. However, such polysaccharide films lack sufficient mechanical properties (especially puncture resistance), making it difficult to adhere to the rough, spiky surface of durians, and their function in actively regulating fruit ripening physiology is limited.

[0003] Alginate (AOS) is a low-molecular-weight, water-soluble functional oligosaccharide that has been shown to delay fruit ripening through molecular mechanisms such as inhibiting ethylene biosynthesis and enhancing the antioxidant system. However, the mechanical strength of a single AOS solution film is limited, making it difficult to withstand the physical challenges of the durian shell. Therefore, to address the shortcomings of existing durian coating preservation technologies, such as insufficient mechanical strength (especially puncture resistance) of the preservation film and weak active regulation of fruit ripening physiology, resulting in short-lasting anti-cracking effects, it is of significant practical value to develop a composite preservative that combines excellent physiological regulatory activity with superior physical and mechanical properties. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a durian anti-cracking preservative based on brown algae oligosaccharides, which can prevent durian from losing weight, delay physiological cracking and improve the mechanical properties of the protective film, as well as its preparation method and application, so as to prevent durian fruit from cracking during post-harvest storage and transportation and extend its shelf life.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: a durian anti-cracking preservative based on fucoidan oligosaccharide, which is composed of the following raw materials in parts by weight: 3-8 parts of fucoidan oligosaccharide, 2-5 parts of sodium caseinate, 0.5-2 parts of guar gum, 100-200 parts of nano-curcumin emulsion, 1-3 parts of glycerin and 300-500 parts of water.

[0006] Furthermore, the nano-curcumin emulsion is prepared by high-speed shear emulsification of curcumin, medium-chain triglycerides, surfactants, and sodium caseinate. By encapsulating hydrophobic curcumin within emulsion particles using nano-emulsification technology, not only can its dispersibility and stability in water-based preservatives be significantly improved, but it can also achieve sustained release after film formation, providing long-lasting antioxidant and antibacterial effects.

[0007] Furthermore, the nano-curcumin emulsion is composed of curcumin, medium-chain triglycerides, surfactant Tween-80, and sodium caseinate solution with a concentration of 1-3 g / mL in a ratio of 0.4-0.6 g: 8-12 g: 1-2 g: 100 mL.

[0008] Furthermore, the brown algae oligosaccharide is a mixture of linear oligosaccharides with a degree of polymerization of 2 to 10 prepared by enzymatic degradation or fermentation.

[0009] The present invention also provides a method for preparing the above-mentioned durian anti-cracking preservative based on fucoidan, comprising the following steps: Step 1: Preparation of nano-curcumin emulsion: Curcumin, medium-chain triglycerides and surfactant Tween-80 are mixed evenly in a mass ratio of (0.4-0.6):(8-12):(1-2) to form the oil phase; sodium caseinate is dissolved in water to obtain a sodium caseinate solution with a concentration of 1-3 g / mL to form the aqueous phase; the aqueous phase is heated to 50-70℃, and the oil phase is added under high-speed shearing, emulsified for 5-15 minutes, and cooled to obtain nano-curcumin emulsion; Step 2: Preparation of the alginic oligosaccharide composite membrane solution: Dissolve alginic oligosaccharides and glycerol in water and stir until completely dissolved. Then add sodium caseinate and guar gum. Stir at 200-400 rpm for 1-2 hours at 40-60℃ to obtain a homogeneous, viscous, light yellow solution, which is the alginic oligosaccharide composite membrane solution. The mass ratio of alginic oligosaccharides, glycerol, water, sodium caseinate, and guar gum is 3-8:1-3:300-500:2-5:0.5-2. Step 3: Preparation of preservative: The nano-curcumin emulsion prepared in Step 1 is added to the brown algae oligosaccharide composite membrane liquid prepared in Step 2 under gentle stirring. Stirring is continued at room temperature for 30-60 minutes, and the mixture is allowed to stand for 2-4 hours to remove bubbles, thereby obtaining a durian anti-cracking preservative based on brown algae oligosaccharide. The mass ratio of nano-curcumin emulsion to brown algae oligosaccharide composite membrane liquid is 100-200:300-500.

[0010] Furthermore, in step 1, the mixing ratio of curcumin, medium-chain triglycerides, surfactant Tween-80, and sodium caseinate solution is 0.4–0.6 g: 8–12 g: 1–2 g: 100 mL.

[0011] The present invention also provides the application of the above-mentioned durian anti-cracking preservative based on brown algae oligosaccharides. The whole durian fruit that has not cracked is completely immersed in the preservative and soaked for 2-5 minutes. After being taken out, it is drained and air-dried naturally until a uniform and transparent protective film is formed on the surface.

[0012] Compared with the prior art, the advantages of the present invention are as follows: 1. The core ingredient AOS fundamentally slows down the ripening and softening process of durian by inhibiting the biosynthesis of ethylene in the fruit. At the same time, AOS can activate the fruit's own antioxidant system, remove excess reactive oxygen species, protect the integrity of cell membrane structure, and reduce the leakage of water and solutes, thereby maintaining the plumpness of the pulp and reducing the driving force for fruit cracking from a physiological perspective.

[0013] 2. This invention innovatively employs sodium caseinate and guar gum as a compound film-forming enhancer for AOS. Sodium caseinate forms a continuous film with high elasticity and strong adhesion, closely adhering to the surface of the durian spikes and grooves; guar gum is a highly efficient thickener that significantly improves the viscosity of the film solution and the toughness of the film after formation. The synergistic effect of these three ingredients effectively resists film damage that may be caused by the hard spikes of the durian shell during stacking and transportation. Glycerin is used as a plasticizer to enhance the film's flexibility.

[0014] 3. Curcumin, introduced through nanoemulsification technology, is stably encapsulated within the emulsion particles and uniformly dispersed within the membrane. During storage, curcumin is slowly released from the membrane, continuously exerting a powerful antioxidant effect, eliminating oxidative stress in the environment. It also inhibits various molds and bacteria, providing antioxidant and antibacterial functions, thus offering a second line of defense for durian preservation.

[0015] 4. All ingredients are of natural origin, biodegradable, and meet food additive safety standards. The preservative is a water-based system, with a simple preparation process requiring no complex equipment. It is applied using an immersion method, making it suitable for large-scale post-harvest processing lines and highly practical.

[0016] In summary, this invention discloses a durian anti-cracking preservative based on fucoidan oligosaccharides, its preparation method, and its application. Using fucoidan oligosaccharides as the core functional matrix, and in conjunction with sodium caseinate, guar gum, nano-curcumin emulsion, and glycerol, a novel composite preservative film with both physical barrier and bioactivity regulating functions is formed. When applied to the surface of durian, this preservative forms a dense, flexible, and strongly adhesive protective film, significantly reducing the weight loss rate of durian during storage, effectively inhibiting ethylene production and respiration, delaying ripening and senescence, and greatly improving the film's puncture resistance. Thus, from both physical barrier and physiological regulation perspectives, it effectively prevents fruit cracking for a long time, significantly extending its shelf life and improving the post-harvest storage and transportation quality and shelf life of durian. Attached Figure Description

[0017] Figure 1 Phenotypes of fruits from different groups after 10 days of storage. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0019] A durian anti-cracking preservative based on fucoidan oligosaccharides is composed of the following raw materials in parts by weight: 3-8 parts fucoidan oligosaccharides, 2-5 parts sodium caseinate, 0.5-2 parts guar gum, 100-200 parts nano-curcumin emulsion, 1-3 parts glycerol, and 300-500 parts water. The nano-curcumin emulsion is prepared by mixing curcumin, medium-chain triglycerides, the surfactant Tween-80, and a 1-3 g / mL sodium caseinate solution in a ratio of 0.4-0.6 g: 8-12 g: 1-2 g: 100 mL.

[0020] Example 1: A method for preparing a durian anti-cracking preservative based on fucoidan oligosaccharides, the specific steps of which are as follows: (1) Preparation of nano-curcumin emulsion: Weigh 0.5g curcumin, 10g medium chain triglyceride (MCT oil) and 1.5g Tween-80, mix them evenly as the oil phase; Weigh 2g sodium caseinate, dissolve it in 100g of pure water at 50℃ as the aqueous phase; Under high-speed shearing at 12000 rpm, slowly drip the oil phase into the aqueous phase, emulsify for 10 minutes to obtain an orange-yellow translucent emulsion, cool it for later use; (2) Preparation of AOS composite membrane solution: Weigh 5g of alginate oligosaccharide (AOS, prepared by enzymatic method, degree of polymerization 8) and 2g of glycerol, add them to 400g of purified water, and stir until completely dissolved. Then add 3g of sodium caseinate and 1g of guar gum, place in a 50℃ water bath, and stir at 300 rpm for 1.5 hours to obtain a homogeneous, viscous, light yellow solution; (3) Mixing: Add all the nano-curcumin emulsion obtained in step (1) to the AOS composite membrane liquid in step (2) under gentle stirring, continue stirring at room temperature for 40 minutes, let stand for 3 hours to defoam, and obtain about 520g of durian anti-cracking preservative finished product.

[0021] Example 2: A method for preparing a durian anti-cracking preservative based on fucoidan oligosaccharides, the specific steps of which are as follows: (1) Preparation of nano-curcumin emulsion: Same as in Example 1; (2) Preparation of AOS composite membrane solution: Weigh 8g AOS, 3g glycerol, 4g sodium caseinate and 1.5g guar gum, and dissolve them in 400g water according to the method in Example 1 to prepare membrane solution; (3) Mixing: Same as in Example 1.

[0022] Comparative Example 1: A preservative was prepared by replacing AOS with an equal amount of chitosan. The preparation method is as follows: (1) Preparation of nano-curcumin emulsion: Same as in Example 1; (2) Preparation of composite membrane solution: Weigh 5g chitosan (deacetamide ≥95%) and 2g glycerol, and dissolve them in 400g water containing 1% acetic acid. After the chitosan is dissolved, add 3g sodium caseinate and 1g guar gum, place in a 50℃ water bath, and stir at 300 rpm for 1.5 hours; (3) Mixing: Same as in Example 1.

[0023] Comparative Example 2: A preservative without sodium caseinate and guar gum. The preparation method is as follows: (1) Preparation of nano-curcumin emulsion: Same as in Example 1; (2) Preparation of AOS membrane solution: Weigh 5g AOS and 2g glycerol, and dissolve them directly in 400g water; (3) Mixing: Add the emulsion to the film solution and stir to mix. The film formed by this formula is very fragile.

[0024] II. Analysis of Experimental Results.

[0025] "Golden Pillow" durians of uniform size and ripeness were selected and randomly divided into four groups. Each group was immersed in the preservatives prepared in Examples 1, 2, 1, and 2 for 3 minutes. Durians without any treatment served as a blank control group. After draining and air-drying, all durians were stored in a cold storage at 13°C and 85-90% relative humidity. Observations and records were kept regularly.

[0026] Test Example 1: Weight Loss and Cracking Rate: The weight of durians was measured every 2 days, and the weight loss rate was calculated. Simultaneously, the number of fruits with visible cracks in the shell and the length of the cracks were recorded, and the cracking rate was calculated. The results on the 10th day of storage are shown in Table 1 below.

[0027] Table 1. Weight loss and cracking rate of durian fruits under different treatments on day 10 of storage.

[0028] Table 1 shows that the blank control group experienced the most severe weight loss and cracking. The weight loss rate in Comparative Example 2 (without reinforcing agent) was improved, indicating that the AOS membrane has a certain water-blocking effect, but the cracking rate was still high, demonstrating insufficient mechanical protection. Comparative Example 1 (chitosan-based) performed better than Comparative Example 2, but both were inferior to the embodiments of this invention. Examples 1 and 2 exhibited the best water retention and crack prevention effects, which is attributed to the synergistic effect of AOS's physiological ripening inhibition and the excellent physical water-locking properties of the composite membrane.

[0029] Test Example 2: Film Puncture Resistance Test: The preservatives from each example and the comparative example were cast into homogeneous films approximately 0.1 mm thick. Using a physical property analyzer and a 1 mm diameter flat-tipped cylindrical probe, the films were punctured at a speed of 1 mm / s, and the maximum puncture force (N) was recorded. Each sample was tested 5 times, and the average value was taken. The results are shown in Table 2 below: Table 2 Maximum puncture force of different preservatives

[0030] As shown in Table 2, the pure AOS film of Comparative Example 2 has the worst mechanical strength. The chitosan composite film of Comparative Example 1 shows improved strength. The films formed in Examples 1 and 2 of this invention have significantly higher puncture resistance than all comparative examples, which verifies the excellent reinforcing effect of sodium caseinate and guar gum on the AOS film, making it sufficient to withstand the physical challenges of durian shells.

[0031] Test Example 3: Phenotypes of fruits from different groups after 10 days of storage. Figure 1 As shown, no cracking occurred in Example 1 and Example 2 groups. Both Comparative Example 1 and Comparative Example 2 showed cracking, with the blank control group exhibiting the most severe cracking. This demonstrates that the preservative of the present invention effectively prevents fruit cracking through both physical barriers and physiological regulation.

[0032] The above experimental results show that the AOS-based composite preservative provided by this invention has significant and synergistic advantages in preventing durian weight loss, delaying physiological cracking, and improving the mechanical properties of the protective film.

[0033] The foregoing description is not intended to limit the invention, nor is the invention limited to the examples given. Any changes, modifications, additions, or substitutions made by those skilled in the art within the scope of the invention should also be considered within the protection scope of the invention.

Claims

1. A durian anti-cracking preservative based on fucoidan oligosaccharides, characterized in that... It is composed of the following raw materials in parts by weight: 3-8 parts of fucoidan, 2-5 parts of sodium caseinate, 0.5-2 parts of guar gum, 100-200 parts of nano-curcumin emulsion, 1-3 parts of glycerin and 300-500 parts of water.

2. The durian anti-cracking preservative based on fucoidan oligosaccharides according to claim 1, characterized in that: The nano-curcumin emulsion is prepared by high-speed shear emulsification of curcumin, medium-chain triglycerides, surfactants and sodium caseinate.

3. The durian anti-cracking preservative based on fucoidan oligosaccharides according to claim 2, characterized in that: The nano-curcumin emulsion is composed of curcumin, medium-chain triglycerides, surfactant Tween-80, and sodium caseinate solution with a concentration of 1-3 g / mL in a ratio of 0.4-0.6 g: 8-12 g: 1-2 g: 100 mL.

4. The durian anti-cracking preservative based on fucoidan oligosaccharides according to claim 1, characterized in that: The brown algae oligosaccharides are a mixture of linear oligosaccharides with a degree of polymerization of 2-10 prepared by enzymatic degradation or fermentation.

5. A method for preparing a durian anti-cracking preservative based on fucoidan according to any one of claims 1-4, characterized in that... Includes the following steps: Step 1: Preparation of nano-curcumin emulsion: Curcumin, medium-chain triglycerides and surfactant Tween-80 are mixed evenly in proportion to form the oil phase; sodium caseinate solution is used as the aqueous phase, and the aqueous phase is added to the oil phase to obtain nano-curcumin emulsion. Step 2: Preparation of the brown algae oligosaccharide composite membrane solution: Dissolve brown algae oligosaccharides and glycerol in water and stir until completely dissolved. Then add sodium caseinate and guar gum to obtain the brown algae oligosaccharide composite membrane solution. Step 3: Preparation of preservative: Add the nano-curcumin emulsion obtained in Step 1 to the brown algae oligosaccharide composite membrane liquid obtained in Step 2 to obtain a durian anti-cracking preservative based on brown algae oligosaccharides.

6. The preparation method according to claim 5, characterized in that... Step 1 is as follows: Curcumin, medium-chain triglycerides, and surfactant Tween-80 are mixed evenly in a certain proportion to form the oil phase; sodium caseinate is dissolved in water to obtain a sodium caseinate solution with a concentration of 1-3 g / mL as the aqueous phase; the aqueous phase is heated to 50-70℃, and the oil phase is added under high-speed shearing, emulsified for 5-15 minutes, and cooled to obtain nano-curcumin emulsion, wherein the mixing ratio of curcumin, medium-chain triglycerides, surfactant Tween-80, and sodium caseinate solution is 0.4-0.6 g: 8-12 g: 1-2 g: 100 mL.

7. The preparation method according to claim 5, characterized in that... Step 2 is as follows: Dissolve fucoidan and glycerol in water and stir until completely dissolved. Then add sodium caseinate and guar gum. Stir at 200-400 rpm for 1-2 hours at 40-60°C to obtain a homogeneous, viscous, light yellow solution, which is the fucoidan-oligosaccharide composite membrane solution. The mass ratio of fucoidan, glycerol, water, sodium caseinate, and guar gum is 3-8:1-3:300-500:2-5:0.5-2.

8. The preparation method according to claim 5, characterized in that... Step 3 is as follows: Add the nano-curcumin emulsion to the brown algae oligosaccharide composite membrane solution under gentle stirring, continue stirring at room temperature for 30-60 minutes, and let stand for 2-4 hours to remove bubbles, to obtain a durian anti-cracking preservative based on brown algae oligosaccharide, wherein the mass ratio of nano-curcumin emulsion to brown algae oligosaccharide composite membrane solution is 100-200:300-500.

9. The application of a durian anti-cracking preservative according to any one of claims 1-4 or a durian anti-cracking preservative prepared by any one of claims 5-8, characterized in that: Completely immerse the unopened durian fruit in the preservative solution for 2-5 minutes. Remove it, drain, and air dry until a uniform, transparent protective film forms on the surface.

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