Food-grade fruit and vegetable cleaning agent as well as preparation method and use method thereof

Abstract

The invention belongs to the technical field of fruit and vegetable cleaning agents, and relates to a food-grade fruit and vegetable cleaning agent as well as a preparation method and a use method thereof, and the food-grade fruit and vegetable cleaning agent comprises nano cellulose powder, starch, calcium hydroxide and sucrose fatty acid ester. According to the fruit and vegetable cleaning agent, efficient and safe fruit and vegetable cleaning is achieved through the multi-component synergistic effect of the nanocellulose, the starch, the calcium hydroxide and the surfactant, on the basis of ensuring food-grade safety, the comprehensive removal efficiency of complex pollutants is remarkably improved, and no harmful residues exist after cleaning.

Description

Technical Field

[0001] The present invention belongs to the technical field of fruit and vegetable cleaning agents, and relates to a food-grade fruit and vegetable cleaning agent, a preparation method thereof, and a usage method thereof. Background Art

[0002] With the increasing attention of people to food safety and health issues, the pesticide, heavy metal, and microbial contamination residues on the surface of fruits and vegetables have become the focus of common concern for consumers and the industry. Traditional fruit and vegetable cleaning agents mostly use chemically synthesized surfactants (such as sodium dodecylbenzenesulfonate) or strongly alkaline components (such as sodium hypochlorite). Although they have a certain decontamination effect, the residue of their components may pose potential hazards to the human body, and there is a risk of damage to the fruit and vegetable cell tissues, which is likely to cause nutrient loss or accelerate spoilage. In recent years, cleaning agents based on natural ingredients have gradually emerged, but the existing technologies still have obvious limitations: although single plant extracts (such as tea polyphenols, citric acid) have relatively high safety, their removal efficiency for fat-soluble pesticides is insufficient; some degradable materials (such as chitosan) are difficult to simultaneously achieve the dual functions of cleaning and preservation due to poor solubility and weak film-forming performance; while physical adsorption-type cleaning agents (such as activated carbon) have problems such as particle residue and inconvenient use. In addition, commercially available food-grade cleaning agents generally lack subsequent preservation support for fruits and vegetables after cleaning, and cannot meet the demand for extending the shelf life of products in scenarios such as fresh food e-commerce and cold chain transportation. In view of the above pain points, developing a composite food-grade cleaning agent with high-efficiency decontamination, safety and non-toxicity, preservation and antibacterial properties, and easy industrial production has become a technical direction that the industry urgently needs to break through. Summary of the Invention

[0003] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a food-grade fruit and vegetable cleaning agent, a preparation method thereof, and a usage method thereof. Through the multi-component synergistic effect of nanocellulose, starch, calcium hydroxide, and surfactant, the present invention realizes the efficient and safe cleaning of fruits and vegetables. On the basis of ensuring food-grade safety, the comprehensive removal efficiency of complex pollutants is significantly improved, and there is no harmful residue after cleaning.

[0004] To achieve this purpose, the present invention adopts the following technical solutions:

[0005] In the first aspect, the present invention provides a food-grade fruit and vegetable cleaning agent, and the food-grade fruit and vegetable cleaning agent includes nanocellulose powder, starch, calcium hydroxide, and sucrose fatty acid ester.

[0006] Through the multi-component synergistic effect of nanocellulose, starch, calcium hydroxide and surfactants, the present invention realizes efficient and safe fruit and vegetable cleaning. Nanocellulose forms a porous adsorption network, which together with starch captures pesticide molecules and heavy metal particles; by adding an appropriate amount of calcium hydroxide, not only can fat-soluble pesticides be decomposed, but also the proliferation of bacteria can be inhibited through the alkaline environment; sucrose fatty acid ester and mono- and diglycerol fatty acid ester cooperate to treat pesticide residues with different polarities respectively, improving the cleaning coverage of the fruit and vegetable cleaning agent. Sodium alginate reacts with calcium hydroxide to form a protective gel layer, prolonging the action time of the active ingredients and preventing the secondary attachment of pollutants. The synergistic effect of each component can not only decompose pesticides and fix heavy metals, but also destroy the cell structure of microorganisms, achieving the effect of sterilization and antibacterial, breaking through the limitation of the single function of traditional cleaning agents, significantly improving the comprehensive removal efficiency of complex pollutants on the basis of ensuring food-grade safety, and having no harmful residues after cleaning.

[0007] As the core functional component, the high specific surface area and surface hydroxyl groups of nanocellulose powder can not only capture organophosphorus pesticide molecules on the surface of fruits and vegetables through physical adsorption, but also form stable complexes with heavy metal ions through coordination.

[0008] The introduction of starch not only improves the suspension stability of nanocellulose as a dispersion carrier, but the glucose units on its molecular chain can also chelate with heavy metals. At the same time, the swelling property of starch under alkaline conditions is conducive to penetrating into the folds of the fruit and vegetable epidermis, strengthening the direct contact with pollutants hidden in the folds of the fruit and vegetable epidermis.

[0009] The strong alkaline environment formed by calcium hydroxide has three functions: on the one hand, through the saponification reaction, the ester bond structure of fat-soluble pesticides is decomposed, making the pesticide molecules more polar and facilitating subsequent cleaning and removal; on the other hand, it can promote heavy metal ions to form hydroxide precipitates under alkaline conditions, blocking their bioavailability; on the other hand, the alkaline environment created by calcium hydroxide effectively inhibits the proliferation of common foodborne pathogenic bacteria such as Escherichia coli.

[0010] As a biosurfactant, sucrose fatty acid ester can not only reduce the surface tension of the aqueous phase to promote the dispersion and infiltration of nanocellulose and starch, but also form micelle structures by emulsifying fat-soluble pesticides. The hydrophobic chain segments in its molecules can also insert into the phospholipid bilayer of the bacterial cell membrane, destroying the integrity of the microbial cell membrane and achieving a long-term bactericidal effect.

[0011] The components of the fruit and vegetable cleaning agent provided by the present invention have a synergistic effect. In terms of pesticide removal, the nano-cellulose powder and starch form a porous adsorption network. The alkaline environment of calcium hydroxide enhances the hydrolysis sensitivity of pesticide molecules, and the presence of sucrose fatty acid ester makes the hydrolysis products more easily captured by the cellulose-starch complex. In terms of heavy metal removal, the precipitation effect of calcium hydroxide and the adsorption effect of nano-cellulose form a double barrier, and the chelating ability of starch secondarily captures the free metal ions that have not been precipitated. In terms of antibacterial, the alkaline environment can effectively inhibit the bacterial metabolic activities, sucrose fatty acid ester can disrupt the cell membrane permeability, and the physical adsorption of nano-cellulose accelerates the shedding of bacteria from the surface of fruits and vegetables. Through the synergistic mechanism of multiple components, the limitations of single components are broken through, and under the premise of ensuring food-grade safety, a broad-spectrum cleaning effect on complex pollutants is achieved.

[0012] As a preferred technical solution of the present invention, based on the mass fraction of the food-grade fruit and vegetable cleaning agent being 100 wt%, it includes the following components with the following mass fractions:

[0013] Nano-cellulose powder: 18 - 20 wt%;

[0014] Starch: 50 - 55 wt%;

[0015] Calcium hydroxide: 15 - 20 wt%;

[0016] Sucrose fatty acid ester: 10 - 15 wt%.

[0017] Among them, the mass fraction of nano-cellulose powder can be 18 wt%, 18.2 wt%, 18.4 wt%, 18.6 wt%, 18.8 wt%, 19 wt%, 19.2 wt%, 19.4 wt%, 19.6 wt%, 19.8 wt% or 20 wt%; the mass fraction of starch can be 50 wt%, 50.5 wt%, 51 wt%, 51.5 wt%, 52 wt%, 52.5 wt%, 53 wt%, 53.5 wt%, 54 wt%, 54.5 wt% or 55 wt%; the mass fraction of calcium hydroxide can be 15 wt%, 15.5 wt%, 16 wt%, 16.5 wt%, 17 wt%, 17.5 wt%, 18 wt%, 18.5 wt%, 19 wt%, 19.5 wt% or 20 wt%; the mass fraction of sucrose fatty acid ester can be 10 wt%, 10.5 wt%, 11 wt%, 11.5 wt%, 12 wt%, 12.5 wt%, 13 wt%, 13.5 wt%, 14 wt%, 14.5 wt% or 15 wt%, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0018] The present invention specifically limits the mass fraction of the nanocellulose powder to 18-20 wt%. The porous network structure formed by the nanocellulose can effectively capture organophosphorus pesticide molecules. Its surface hydroxyl groups form coordination bonds with heavy metal ions, and at the same time, a three-dimensional adsorption network framework is constructed through hydrogen bonding with starch molecules to enhance the interception ability of pollutants. In addition, an appropriate amount of nanocellulose can also increase the adsorption sites of microorganisms in the cleaning solution, limit the activity range of bacteria, and synergistically improve the antibacterial effect with the membrane-damaging effect of sucrose fatty acid ester. At the same time, the dispersion state of the nanocellulose at this addition amount is optimal, which can not only avoid the agglomeration phenomenon caused by excessive nanocellulose but also ensure a sufficient number of active sites to cover the surface of fruits and vegetables.

[0019] When the mass fraction of the nanocellulose powder is lower than 18 wt%, the density of the adsorption network structure formed by the nanocellulose is insufficient, resulting in an increase in porosity. Pesticide molecules are easily penetrated through the three-dimensional adsorption network structure and undergo secondary adsorption. In addition, the insufficient addition amount of the nanocellulose powder leads to a reduction in the number of ligand sites and an increase in the residual amount of heavy metal ions. At the same time, microorganisms are more likely to reattach to the surface of fruits and vegetables in a low-concentration nanocellulose solution, weakening the antibacterial persistence.

[0020] When the mass fraction of the nanocellulose powder exceeds 20 wt%, the excessive nanofiber structures entangle with each other to form dense aggregates, which hinder the contact interface between the sucrose fatty acid ester and the pesticide and affect the progress of the saponification reaction. In addition, the excessive addition amount of the nanocellulose powder leads to an increase in the viscosity of the cleaning solution. Microorganisms are more likely to adsorb inside the fiber network rather than on the surface of fruits and vegetables, resulting in a decrease in the antibacterial effect. At the same time, the excessively piled nanocellulose will wrap the calcium hydroxide particles, delaying their dissolution rate and affecting the adjustment of the pH value of the cleaning solution.

[0021] The present invention specifically limits the mass fraction of the starch to 50-55 wt%. As the main carrier, the entanglement of the molecular chains of the starch forms a three-dimensional network structure, which uniformly disperses the nanocellulose and calcium hydroxide in the cleaning solution system to prevent the sedimentation of solid particles. In addition, after adding an appropriate amount of starch, the swollen starch solution has an appropriate viscosity, which can not only penetrate the folds of the fruit and vegetable epidermis to enhance the direct contact of the cleaning solution with hidden pollutants but also bind to pesticide molecules through hydrogen bonding and synergistically improve the emulsification efficiency of lipophilic substances with the sucrose fatty acid ester. At the same time, the hydroxyl groups of the starch have a coordination effect with heavy metal ions, producing a dual capture effect with the precipitation effect of calcium hydroxide.

[0022] When the mass fraction of starch is lower than 50 wt%, the insufficient viscosity of the cleaning solution leads to a decrease in dispersion stability. The nanocellulose is prone to agglomeration, losing its high specific surface area advantage, and the calcium hydroxide particles settle due to weakened Brownian motion, causing local pH fluctuations in the cleaning solution. In addition, the physical adsorption capacity of the low-viscosity cleaning solution for pesticide molecules decreases, and some degradation products will reattach to the fruit and vegetable surfaces due to lack of encapsulation. Moreover, the reduction of chelation sites on the starch hydroxyl groups weakens the ability to fix free heavy metal ions. At the same time, the cleaning solution with too low viscosity is difficult to form a continuous liquid film on the fruit and vegetable surfaces, affecting the continuous antibacterial effect of the alkaline environment.

[0023] When the mass fraction of starch exceeds 55 wt%, the overly viscous cleaning solution will limit the migration and diffusion of nanocellulose and calcium hydroxide. The active surfaces of nanocellulose and calcium hydroxide are wrapped by starch molecules, resulting in reduced adsorption and reaction efficiency. In addition, the penetration of the high-viscosity cleaning solution on the fruit and vegetable surfaces is blocked, causing cleaning blind spots, and the unswollen lumps may remain on the fruit and vegetable surfaces, instead becoming carriers for secondary deposition of pollutants.

[0024] The present invention specifically limits the mass fraction of calcium hydroxide to 15 - 20 wt%. The alkaline environment generated by the dissolution of calcium hydroxide can not only achieve the hydrolysis and cleavage of the ester bonds of fat-soluble pesticides, but also promote the formation of hydroxide precipitates of heavy metal ions. At the same time, the appropriate alkaline environment can also inhibit the enzyme activity of microorganisms such as Escherichia coli, and achieve antibacterial effects by destroying the cell membrane potential. In addition, the ion cross-linking effect between calcium hydroxide and sodium alginate can form a microgel structure, enhancing the adhesion and coverage of the cleaning solution on the fruit and vegetable surfaces and prolonging the action time of the active ingredients.

[0025] When the mass fraction of calcium hydroxide is lower than 15 wt%, the alkalinity of the cleaning solution is insufficient, resulting in a significant decrease in the hydrolysis reaction rate of pesticides. The heavy metal ions cannot be completely precipitated due to insufficient OH - concentration and remain in the cleaning solution in a soluble state, posing a risk of secondary pollution. In addition, the insufficient alkalinity of the cleaning solution will also weaken the destructive effect of the cleaning solution on the cell membranes of microorganisms, resulting in a decrease in the antibacterial rate of the cleaning solution. At the same time, due to insufficient calcium ion concentration in the cleaning solution, sodium alginate is difficult to form a stable gel network structure, resulting in a shortened retention time of the cleaning solution on the fruit and vegetable surfaces and affecting the cleaning effect.

[0026] When the mass fraction of calcium hydroxide exceeds 20 wt%, the alkalinity of the cleaning solution is too strong, causing damage to the cell membranes on the surfaces of fruits and vegetables, resulting in the dissolution and loss of nutrients such as vitamin C. In addition, excessive calcium ions combine with the carboxylic acid groups of sucrose fatty acid esters to form precipitates, affecting the emulsification efficiency of sucrose fatty acid esters and making it impossible to effectively remove fat-soluble pesticides. At the same time, some hydroxyl groups of nanocellulose are deprotonated in a highly alkaline environment, generating electrostatic repulsion with calcium ions, resulting in a reduction in adsorption sites and a decrease in the heavy metal removal efficiency. During actual use, too high an addition amount of calcium hydroxide causes undissolved calcium hydroxide in the cleaning solution to easily form white residues on the surfaces of fruits and vegetables, not only increasing the rinsing difficulty but also affecting the user experience.

[0027] The present invention specifically limits the mass fraction of sucrose fatty acid ester to 10 - 15 wt%. The hydrophilic-lipophilic balance value of sucrose fatty acid ester matches the polarity of fat-soluble pesticides. By reducing the interfacial tension, it promotes the emulsification of pesticides into micron-sized micelles. At the same time, the steric hindrance formed by the directional arrangement of its molecules can prevent the re-adsorption of heavy metal ions. Adding an appropriate amount of sucrose fatty acid ester can also ensure the stable dispersion of nanocellulose and calcium hydroxide, avoiding the aggregation and inactivation of nanocellulose and calcium hydroxide due to van der Waals forces.

[0028] When the mass fraction of sucrose fatty acid ester is lower than 10 wt%, the micelle concentration of sucrose fatty acid ester is insufficient, resulting in the ineffective emulsification of fat-soluble pesticides, and some uncoated pesticide degradation products will redeposit on the surfaces of fruits and vegetables. In addition, local aggregation of nanocellulose occurs due to insufficient sucrose fatty acid ester, reducing the specific surface area and directly affecting the adsorption efficiency of heavy metals. At the same time, the coverage of the microbial cell membranes by sucrose fatty acid ester decreases, and the antibacterial efficiency is reduced.

[0029] When the mass fraction content of sucrose fatty acid ester exceeds 15 wt%, excessive sucrose fatty acid ester combines with calcium ions to produce calcium sucrose fatty acid precipitate, resulting in the inactivation of some active ingredients and weakening the emulsification ability for pesticides. In addition, too high an addition amount of sucrose fatty acid ester will also cause excessive aggregation of micelles, covering the active sites on the surface of nanocellulose and causing a decrease in the heavy metal adsorption rate. At the same time, the dense adsorption layer formed by a high concentration of sucrose fatty acid ester will hinder the migration of OH - ions, resulting in a decrease in the rate of pesticide hydrolysis reaction and affecting the pesticide removal effect of the cleaning solution on fruits and vegetables.

[0030] As a preferred technical solution of the present invention, the food-grade fruit and vegetable cleaning agent further includes mono- and diglycerol fatty acid esters.

[0031] In terms of antibacterial effects, the synergistic effect of mono- and diglycerol fatty acid esters and sucrose fatty acid esters can significantly enhance the antibacterial ability of fruit and vegetable cleaners. The hydrophobic alkyl chains of mono- and diglycerol fatty acid esters preferentially embed in the hydrophobic region of the microbial cell membrane, increasing the fluidity of the cell membrane and disrupting the orderliness of the phospholipid arrangement; while the polyhydroxy structure of sucrose fatty acid esters competitively binds to the cell membrane surface proteins through hydrogen bonds, interfering with transmembrane material transport. The synergistic effect of the two causes local defects in the lipid bilayer of the cell membrane, resulting in a significant increase in the leakage of intracellular electrolytes and metabolites, thus achieving the combined inactivation effect on common foodborne pathogenic bacteria such as Escherichia coli.

[0032] In terms of pesticide removal, the hydrophilic-lipophilic balance (HLB) values of mono- and diglycerol fatty acid esters and sucrose fatty acid esters are complementary, forming a hierarchical emulsification effect. Mono- and diglycerol fatty acid esters (HLB value of 4 - 8) insert into the benzene ring structure of pyrethroid pesticides through hydrophobic interactions, disrupting their van der Waals force binding with the wax layer of fruit and vegetable epidermis; sucrose fatty acid esters (HLB value of 11 - 15) then encapsulate the detached pesticide molecules in the hydrophilic outer shell of the micelles through steric hindrance, thus forming water-soluble micelle particles. The composite micelles formed by the combination of the two can not only handle strongly hydrophobic pesticides but also emulsify moderately polar residues, expanding the removal coverage range for pesticides with different polarities.

[0033] In terms of heavy metal removal, the free hydroxyl groups of mono- and diglycerol fatty acid esters form weak coordination bonds with heavy metal ions, promoting the desorption of metal ions from the fruit and vegetable surface into the cleaning solution; sucrose fatty acid esters maintain the dispersed state of nanocellulose through electrostatic repulsion, ensuring the full exposure of its surface hydroxyl and carboxyl sites. The two form a dual effect of "desorption - fixation". Mono- and diglycerol fatty acid esters are responsible for breaking the ionic bond between heavy metals and pectin on the fruit and vegetable epidermis, while sucrose fatty acid esters prevent the aggregation of nanocellulose by regulating the Zeta potential of the cleaning solution, ultimately achieving the efficient chelation and stable fixation of heavy metal ions.

[0034] In some optional examples, the mass ratio of the sucrose fatty acid ester to the mono- and diglycerol fatty acid ester is (3 - 5):1. For example, it can be 3.0:1, 3.2:1, 3.4:1, 3.6:1, 3.8:1, 4.0:1, 4.2:1, 4.4:1, 4.6:1, 4.8:1 or 5.0:1, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0035] The present invention specifically defines that the mass ratio of sucrose fatty acid ester to mono- and diglycerol fatty acid esters is (3-5):1. The sucrose fatty acid ester is used to form oil-in-water micelles due to its high hydrophilicity, effectively encapsulating moderately polar pesticides such as organophosphorus pesticides. The mono- and diglycerol fatty acid esters utilize their hydrophobic properties to insert into the molecular gaps of highly hydrophobic pyrethroid pesticides, disrupting their binding with the wax layer of fruits and vegetables. The synergistic effect of the two makes the core of the micelles form a gradient polarity distribution, improving the encapsulation efficiency of pesticides with different polarities.

[0036] When the addition amount of sucrose fatty acid ester is lower than the lower limit of the range defined in the present invention, the hydrophilicity of the cleaning solution is insufficient, resulting in a decrease in the stability of the micelles and a significant reduction in the emulsification efficiency of moderately polar pesticides. At the same time, an excessive amount of mono- and diglycerol fatty acid esters forms reverse micelles that are easily adsorbed on the surface of nanocellulose, hindering its coordination with heavy metal ions. In addition, calcium hydroxide in the cleaning solution is covered by the hydrophobic layer of the surfactant, making it difficult to fully contact the pesticide molecules for saponification reaction, resulting in the redeposition of residual pesticide degradation products on the surface of fruits and vegetables.

[0037] When the addition amount of sucrose fatty acid ester is higher than the upper limit of the range defined in the present invention, the excessive hydrophilic groups lead to an increase in the rigidity of the micelle shell, resulting in a decrease in the encapsulation ability of highly hydrophobic pesticides. In addition, the precipitation formed by the binding of surfactant molecules to calcium ions increases, not only losing the active ingredients but also encapsulating calcium hydroxide particles, making it difficult for calcium hydroxide to fully contact the pesticide molecules and affecting the progress of the saponification reaction. At the same time, the hydroxyl sites on the surface of nanocellulose are reduced due to the dense adsorption of sucrose fatty acid ester molecules, directly affecting the fixation efficiency of nanocellulose for heavy metals.

[0038] As a preferred technical solution of the present invention, the food-grade fruit and vegetable cleaning agent further includes sodium alginate.

[0039] The present invention also adds sodium alginate to the food-grade fruit and vegetable cleaning agent. The Ca released by calcium hydroxide 2+ forms a coordination bond with the carboxylate group (-COO - ) on the molecular chain of sodium alginate to form a three-dimensional network gel structure. This gel network structure forms a physical barrier on the surface of fruits and vegetables, not only prolonging the action time of the alkaline environment of calcium hydroxide but also capturing pesticide degradation products through the molecular sieve effect. In terms of antibacterial, the gel network forms a spatial barrier effect on microorganisms, restricting their activity range, and at the same time, the slowly released OH - continuously destroys the integrity of the bacterial cell membrane. In terms of pesticide removal, the gel network structure encapsulates and isolates the hydrophobic pesticide degradation products generated by the saponification reaction through the size exclusion effect, preventing them from redepositing on the surface of fruits and vegetables. In terms of heavy metal removal, the carboxyl groups of sodium alginate preferentially form coordination bonds with heavy metals such as Pb 2+ , Cd 2+ , etc., while Ca 2+Heavy metals are dissociated from the surfaces of fruits and vegetables through competitive displacement. Meanwhile, the spatial confinement effect of the gel network delays the aggregation and sedimentation rate of heavy metal hydroxides, ensuring that nanocellulose has sufficient time to adsorb and fix heavy metal hydroxides.

[0040] In some optional examples, the mass ratio of the calcium hydroxide to the sodium alginate is 1:(0.3 - 0.5), for example, it can be 1:0.3, 1:0.32, 1:0.34, 1:0.36, 1:0.38, 1:0.4, 1:0.42, 1:0.44, 1:0.46, 1:0.48 or 1:0.5. However, it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0041] The present invention specifically defines the mass ratio of calcium hydroxide to sodium alginate as 1:(0.3 - 0.5). The carboxylic acid groups of sodium alginate and Ca released by calcium hydroxide 2+ form a moderately crosslinked three - dimensional network structure, which can not only maintain the adhesion of the cleaning solution on the surface of fruits and vegetables to extend the alkaline action time, but also avoid the decrease in the permeability of the cleaning solution caused by excessive crosslinking. The gel network structure restricts the re - adsorption of pesticide degradation products through physical barrier effects. Meanwhile, the appropriate addition of sodium alginate can also buffer the pH value fluctuation of the cleaning solution, ensuring both the saponification reaction efficiency and reducing the damage to the surfaces of fruits and vegetables caused by excessive alkalinity.

[0042] When the addition amount of sodium alginate is lower than the lower limit of the range defined in the present invention, the cross - linking point density is insufficient, resulting in a loose gel structure. The calcium hydroxide particles are prone to rapid sedimentation, causing the local pH value of the cleaning solution to be too high, leading to damage to the cell membranes on the surfaces of fruits and vegetables. In addition, the interception efficiency of the loose gel structure for pesticide degradation products decreases, resulting in some pesticide degradation products re - attaching to the surfaces of fruits and vegetables. At the same time, the insufficient number of carboxylic acid groups of sodium alginate weakens the coordination ability with heavy metals, leading to the secondary diffusion of unbound heavy metal ions.

[0043] When the addition amount of sodium alginate is higher than the upper limit of the range defined in the present invention, the formation of a dense gel network structure due to excessive cross - linking will hinder the migration of nanocellulose, sucrose fatty acid esters and mono - and diglycerol fatty acid esters to the pollution sites. Meanwhile, calcium hydroxide is wrapped inside the gel, resulting in a reduction in the effective contact area between calcium hydroxide and pesticides, affecting the saponification reaction of pesticides. In addition, the dense gel layer forms a penetration barrier on the surfaces of fruits and vegetables, making it difficult for the cleaning solution to penetrate into the epidermal folds of fruits and vegetables, so that some pollutants hidden in the folds cannot be removed. Moreover, excessive sodium alginate will also bind excessively with heavy metal ions, occupying the adsorption sites of nanocellulose, instead reducing the fixation efficiency of heavy metals.

[0044] In a second aspect, the present invention provides a preparation method of the food - grade fruit and vegetable cleaning agent described in the first aspect. The preparation method includes:

[0045] Mix the nanocellulose powder, starch, calcium hydroxide, and sucrose fatty acid ester evenly in proportion to obtain the food-grade fruit and vegetable cleaning agent.

[0046] As a preferred technical solution of the present invention, the preparation method includes:

[0047] Mix the nanocellulose powder, starch, calcium hydroxide, sucrose fatty acid ester, mono- and diglycerol fatty acid ester, and sodium alginate evenly in proportion to obtain the food-grade fruit and vegetable cleaning agent.

[0048] In the third aspect, the present invention provides a method for using the food-grade fruit and vegetable cleaning agent described in the first aspect, and the method for using includes:

[0049] Add the food-grade fruit and vegetable cleaning agent to water, and after mixing evenly, obtain a cleaning solution; soak the fruits and vegetables to be cleaned in the cleaning solution, take them out after soaking for a period of time, and rinse them clean with clean water.

[0050] As a preferred technical solution of the present invention, the mixing ratio of the food-grade fruit and vegetable cleaning agent and water is (1.5~2.5) g:1 L. For example, it can be 1.5 g:1 L, 1.6 g:1 L, 1.7 g:1 L, 1.8 g:1 L, 1.9 g:1 L, 2.0 g:1 L, 2.1 g:1 L, 2.2 g:1 L, 2.3 g:1 L, 2.4 g:1 L, or 2.5 g:1 L, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0051] In some alternative examples, the temperature of the water is 30~40 °C. For example, it can be 30 °C, 31 °C, 32 °C, 33 °C, 34 °C, 35 °C, 36 °C, 37 °C, 38 °C, 39 °C, or 40 °C, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0052] In some alternative examples, the soaking time of the fruits and vegetables to be cleaned in the cleaning solution is 5~10 min. For example, it can be 5.0 min, 5.5 min, 6.0 min, 6.5 min, 7.0 min, 7.5 min, 8.0 min, 8.5 min, 9.0 min, 9.5 min, or 10.0 min, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0053] Compared with the prior art, the beneficial effects of the present invention are:

[0054] Through the multi-component synergistic effect of nanocellulose, starch, calcium hydroxide and surfactants, the present invention realizes efficient and safe cleaning of fruits and vegetables. Nanocellulose forms a porous adsorption network, which together with starch captures pesticide molecules and heavy metal particles; by adding an appropriate amount of calcium hydroxide, not only can fat-soluble pesticides be decomposed, but also the proliferation of bacteria can be inhibited through an alkaline environment; sucrose fatty acid ester and mono- and diglycerol fatty acid ester cooperate to treat pesticide residues with different polarities respectively, improving the cleaning coverage of the fruit and vegetable cleaning agent. Sodium alginate reacts with calcium hydroxide to form a protective gel layer, prolonging the action time of the active ingredients and preventing secondary attachment of pollutants. The synergistic effect of each component can not only decompose pesticides and fix heavy metals, but also destroy the cell structure of microorganisms, achieving a bactericidal and antibacterial effect, breaking through the limitation of the single action of traditional cleaning agents. On the basis of ensuring food-grade safety, the comprehensive removal efficiency of complex pollutants is significantly improved, and there is no harmful residue after cleaning. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is a colony map of Escherichia coli after cleaning an apple with the food-grade fruit and vegetable cleaning agent provided in Example 6;

[0056] Figure 2 It is a colony map of Escherichia coli after cleaning an apple with sterile water. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0057] The technical solution of the present invention will be described in detail below in conjunction with specific embodiments and their accompanying drawings. The embodiments described herein are specific specific embodiments of the present invention and are used to illustrate the concept of the present invention; these descriptions are all explanatory and exemplary, and should not be construed as a limitation on the embodiments of the present invention and the protection scope of the present invention. Except for the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the content disclosed in the claims and the specification of this application, and these technical solutions include technical solutions that make any obvious substitutions and modifications to the embodiments described herein.

[0058] Example 1

[0059] This embodiment provides a food-grade fruit and vegetable cleaning agent. Based on the mass fraction of the food-grade fruit and vegetable cleaning agent being 100 wt%, it includes the following components with the following mass fractions:

[0060] Nanocellulose powder 18 wt%;

[0061] Starch 55 wt%;

[0062] Calcium hydroxide 17 wt%;

[0063] Sucrose fatty acid ester 10 wt%.

[0064] Example 2

[0065] This embodiment provides a food-grade fruit and vegetable cleaning agent. Calculated based on the mass fraction of the food-grade fruit and vegetable cleaning agent being 100 wt%, it includes the following components with the following mass fractions:

[0066] Nano-cellulose powder 18 wt%;

[0067] Starch 50 wt%;

[0068] Calcium hydroxide 20 wt%;

[0069] Sucrose fatty acid ester 12 wt%.

[0070] Example 3

[0071] This embodiment provides a food-grade fruit and vegetable cleaning agent. Calculated based on the mass fraction of the food-grade fruit and vegetable cleaning agent being 100 wt%, it includes the following components with the following mass fractions:

[0072] Nano-cellulose powder 20 wt%;

[0073] Starch 50 wt%;

[0074] Calcium hydroxide 15 wt%;

[0075] Sucrose fatty acid ester 15 wt%.

[0076] Example 4

[0077] This embodiment provides a food-grade fruit and vegetable cleaning agent. Calculated based on the mass fraction of the food-grade fruit and vegetable cleaning agent being 100 wt%, it includes the following components with the following mass fractions:

[0078] Nano-cellulose powder 18 wt%;

[0079] Starch 55 wt%;

[0080] Calcium hydroxide 17 wt%;

[0081] Sucrose fatty acid ester 10 wt%.

[0082] The food-grade fruit and vegetable cleaning agent also includes mono- and diglycerol fatty acid esters and sodium alginate. The mass ratio of sucrose fatty acid ester to mono- and diglycerol fatty acid esters is 3:1, and the mass ratio of calcium hydroxide to sodium alginate is 1:0.3.

[0083] Example 5

[0084] This embodiment provides a food-grade fruit and vegetable cleaning agent. Calculated based on the mass fraction of the food-grade fruit and vegetable cleaning agent being 100 wt%, it includes the following components with the following mass fractions:

[0085] Nanocellulose powder 18 wt%;

[0086] Starch 55 wt%;

[0087] Calcium hydroxide 17 wt%;

[0088] Sucrose fatty acid ester 10 wt%.

[0089] The food-grade fruit and vegetable cleaning agent further includes mono- and diglycerol fatty acid esters and sodium alginate. The mass ratio of sucrose fatty acid ester to mono- and diglycerol fatty acid esters is 3.5:1, and the mass ratio of calcium hydroxide to sodium alginate is 1:0.35.

[0090] [[ID=1,7]] Example 6

[0091] This embodiment provides a food-grade fruit and vegetable cleaning agent. Based on the mass fraction of the food-grade fruit and vegetable cleaning agent being 100 wt%, it includes the following components with the following mass fractions:

[0092] Nanocellulose powder 18 wt%;

[0093] Starch 55 wt%;

[0094] Calcium hydroxide 17 wt%;

[0095] Sucrose fatty acid ester 10 wt%.

[0096] The food-grade fruit and vegetable cleaning agent further includes mono- and diglycerol fatty acid esters and sodium alginate. The mass ratio of sucrose fatty acid ester to mono- and diglycerol fatty acid esters is 4:1, and the mass ratio of calcium hydroxide to sodium alginate is 1:0.4.

[0097] Example 7

[0098] This embodiment provides a food-grade fruit and vegetable cleaning agent. Based on the mass fraction of the food-grade fruit and vegetable cleaning agent being 100 wt%, it includes the following components with the following mass fractions:

[0099] Nanocellulose powder 18 wt%;

[0100] Starch 55 wt%;

[0101] Calcium hydroxide 17 wt%;

[0102] Sucrose fatty acid ester 10 wt%.

[0103] The food-grade fruit and vegetable cleaning agent further includes mono- and diglycerol fatty acid esters and sodium alginate. The mass ratio of sucrose fatty acid ester to mono- and diglycerol fatty acid esters is 4.5:1, and the mass ratio of calcium hydroxide to sodium alginate is 1:0.45.

[0104] Example 8

[0105] This embodiment provides a food-grade fruit and vegetable cleaning agent. Based on the mass fraction of the food-grade fruit and vegetable cleaning agent being 100 wt%, it includes the following components with the following mass fractions:

[0106] Nano-cellulose powder 18 wt%;

[0107] Starch 55 wt%;

[0108] Calcium hydroxide 17 wt%;

[0109] Sucrose fatty acid ester 10 wt%.

[0110] The food-grade fruit and vegetable cleaning agent also includes mono- and diglycerol fatty acid esters and sodium alginate. The mass ratio of sucrose fatty acid ester to mono- and diglycerol fatty acid esters is 5:1, and the mass ratio of calcium hydroxide to sodium alginate is 1:0.5.

[0111] Example 9

[0112] This embodiment provides a food-grade fruit and vegetable cleaning agent, which is different from Embodiment 6 in that the mass fraction of nano-cellulose powder is adjusted to 15 wt%, and the mass fractions of other components are increased proportionally to ensure that the ratio between other components except nano-cellulose powder remains unchanged. Specifically as follows:

[0113] Nano-cellulose powder 15 wt%;

[0114] Starch 57.0 wt%;

[0115] Calcium hydroxide 17.6 wt%;

[0116] Sucrose fatty acid ester 10.4 wt%.

[0117] Example 10

[0118] This embodiment provides a food-grade fruit and vegetable cleaning agent, which is different from Embodiment 6 in that the mass fraction of nano-cellulose powder is adjusted to 25 wt%, and the mass fractions of other components are decreased proportionally to ensure that the ratio between other components except nano-cellulose powder remains unchanged. Specifically as follows:

[0119] Nano-cellulose powder 25 wt%;

[0120] Starch 50.3 wt%;

[0121] Calcium hydroxide 15.5 wt%;

[0122] Sucrose fatty acid ester 9.2 wt%.

[0123] Example 11

[0124] This embodiment provides a food-grade fruit and vegetable cleaning agent, which is different from that of Embodiment 6 in that the mass fraction of starch is adjusted to 45 wt%, and the mass fractions of other components are increased proportionally to ensure that the ratio between other components except starch remains unchanged. Specifically as follows:

[0125] Nano-cellulose powder 22 wt%;

[0126] Starch 45 wt%;

[0127] Calcium hydroxide 20.8 wt%;

[0128] Sucrose fatty acid ester 12.2 wt%.

[0129] Example 12

[0130] This embodiment provides a food-grade fruit and vegetable cleaning agent, which is different from that of Embodiment 6 in that the mass fraction of starch is adjusted to 60 wt%, and the mass fractions of other components are decreased proportionally to ensure that the ratio between other components except starch remains unchanged. Specifically as follows:

[0131] Nano-cellulose powder 16 wt%;

[0132] Starch 60 wt%;

[0133] Calcium hydroxide 15.1 wt%;

[0134] Sucrose fatty acid ester 8.9 wt%.

[0135] Example 13

[0136] This embodiment provides a food-grade fruit and vegetable cleaning agent, which is different from that of Embodiment 6 in that the mass fraction of calcium hydroxide is adjusted to 10 wt%, and the mass fractions of other components are increased proportionally to ensure that the ratio between other components except calcium hydroxide remains unchanged. Specifically as follows:

[0137] Nano-cellulose powder 19.5 wt%;

[0138] Starch 59.6 wt%;

[0139] Calcium hydroxide 10 wt%;

[0140] Sucrose fatty acid ester 10.9 wt%.

[0141] Example 14

[0142] This example provides a food-grade fruit and vegetable cleaning agent. The difference from Example 6 is that the mass fraction of calcium hydroxide is adjusted to 25 wt%, and the mass fractions of other components are reduced proportionally to ensure that the ratio between other components except calcium hydroxide remains unchanged. Specifically as follows:

[0143] Nano-cellulose powder 16.3 wt%;

[0144] Starch 49.7 wt%;

[0145] Calcium hydroxide 25 wt%;

[0146] Sucrose fatty acid ester 9 wt%.

[0147] Example 15

[0148] This example provides a food-grade fruit and vegetable cleaning agent. The difference from Example 6 is that the mass fraction of sucrose fatty acid ester is adjusted to 5 wt%, and the mass fractions of other components are increased proportionally to ensure that the ratio between other components except sucrose fatty acid ester remains unchanged. Specifically as follows:

[0149] Nano-cellulose powder 19 wt%;

[0150] Starch 58.1 wt%;

[0151] Calcium hydroxide 17.9 wt%;

[0152] Sucrose fatty acid ester 5 wt%.

[0153] Example 16

[0154] This example provides a food-grade fruit and vegetable cleaning agent. The difference from Example 6 is that the mass fraction of sucrose fatty acid ester is adjusted to 20 wt%, and the mass fractions of other components are reduced proportionally to ensure that the ratio between other components except sucrose fatty acid ester remains unchanged. Specifically as follows:

[0155] Nano-cellulose powder 16 wt%;

[0156] Starch 48.9 wt%;

[0157] Calcium hydroxide 15.1 wt%;

[0158] Sucrose fatty acid ester 20 wt%.

[0159] Example 17

[0160] This example provides a food-grade fruit and vegetable cleaning agent. The difference from Example 6 is that the mass ratio of sucrose fatty acid ester to mono- and diglycerol fatty acid esters is adjusted to 2:1, and the addition amounts of other components remain unchanged.

[0161] Example 18

[0162] This embodiment provides a food-grade fruit and vegetable cleaning agent, which is different from that of Example 6 in that the mass ratio of sucrose fatty acid ester to mono- and diglycerol fatty acid esters is adjusted to 7:1, and the addition amounts of other components remain unchanged.

[0163] Example 19

[0164] This embodiment provides a food-grade fruit and vegetable cleaning agent, which is different from that of Example 6 in that the mass ratio of calcium hydroxide to sodium alginate is adjusted to 1:0.1, and the addition amounts of other components remain unchanged.

[0165] Example 20

[0166] This embodiment provides a food-grade fruit and vegetable cleaning agent, which is different from that of Example 6 in that the mass ratio of calcium hydroxide to sodium alginate is adjusted to 1:0.8, and the addition amounts of other components remain unchanged.

[0167] Application Example

[0168] This application example provides a method for using a food-grade fruit and vegetable cleaning agent with functions of sterilization, pesticide residue removal and heavy metal removal, which specifically includes the following steps:

[0169] Add 2 g of the food-grade fruit and vegetable cleaning agent to 1 L of warm water at 30°C, mix evenly to obtain a cleaning solution; soak the fruits and vegetables to be cleaned in the cleaning solution, take them out after soaking for 5 min, and rinse them clean with clean water.

[0170] Test the bactericidal performance, pesticide residue removal ability and heavy metal removal ability of the food-grade fruit and vegetable cleaning agents prepared in Examples 1-20. The test steps are as follows:

[0171] (1) Escherichia coli bactericidal rate

[0172] Use the Escherichia coli bactericidal rate to evaluate the bactericidal performance of the food-grade fruit and vegetable cleaning agent. The specific test steps are as follows:

[0173] Inoculate Escherichia coli (ATCC 25922) into TSB medium, culture it at 37°C for 18-24 hours, and adjust the concentration to 1×10 8 CFU / mL with PBS to obtain a bacterial suspension. Prepare D / E neutralizing broth containing 0.5% sodium thiosulfate + 1% lecithin.

[0174] Take 1 mL of the bacterial suspension, add 9 mL of the cleaning solution (2 g / L) prepared according to the application example thereto, and vortex and stir for 5 - 10 min under the condition of water bath heating at 30 °C (simulating the actual soaking condition) to obtain a mixed solution; aspirate 1 mL of the mixed solution, add 9 mL of D / E neutralizing broth thereto, and vortex and mix evenly for 5 - 10 min to obtain a culture solution.

[0175] Take 0.1 mL of the culture solution and spread it on a TSA plate, and culture it at 37 °C for 24 h to obtain Figure 1 the Escherichia coli colony map shown as (using the food-grade fruit and vegetable cleaning agent provided in Example 6), count the surviving colonies, and obtain the number of colonies in the treatment group.

[0176] Set up a blank group, replace the cleaning solution with sterile water, add 9 mL of sterile water to 1 mL of the bacterial suspension, and keep other operating conditions the same as above, and culture it at 37 °C for 24 h to obtain Figure 2 the Escherichia coli colony map shown as, count the surviving colonies, and obtain the number of colonies in the blank group.

[0177] Calculate the sterilization rate according to the number of colonies in the treatment group and the number of colonies in the blank group. The calculation formula is as follows:

[0178] Sterilization rate = (1 - number of colonies in the treatment group / number of colonies in the blank group) × 100%.

[0179] (2) Lead ion removal rate

[0180] Refer to the national standard GB 5009.12 - 2017 "National Food Safety Standard - Determination of Lead in Foods" to determine the lead ion removal rate. The specific test steps are as follows:

[0181] Soak the apple skin in a lead standard solution (prepared with lead nitrate) containing 1 mg / L for 2 h, and air dry it to obtain a contaminated sample.

[0182] Set up a treatment group, perform cleaning treatment on the contaminated sample according to the usage method provided in the application example, and then take 10 g of the treated contaminated sample, add a nitric acid / hydrogen peroxide (5:1) mixed solution, digest it with a microwave digester, and detect the lead element content in the treatment group by the internal standard method.

[0183] Set up a blank group, use the unwashed apple skin as the blank group, and detect the lead element content in the blank group by the internal standard method.

[0184] Heavy metal removal rate = (1 - lead element content in the treatment group / lead element content in the blank group) × 100%.

[0185] (3) Fenvalerate pesticide removal rate

[0186] The pesticide residue was determined with reference to the national standard GB 23200.113-2018 National Food Safety Standard - Determination of Residues of 208 Pesticides and Their Metabolites in Plant-derived Foods. The specific test steps are as follows:

[0187] Set up the treatment group. Clean the apple skin using the application method provided in the application example, chop the cleaned apple skin, and perform pretreatment using the QuEChERS method. Prepare a series of fenvalerate standard solutions with concentrations ranging from 0.005 to 0.5 mg / L, establish an external standard curve, and determine the pesticide residue in the treatment group using the external standard method.

[0188] Set up the blank group. Use the unwashed apple skin as the blank group and determine the pesticide residue in the blank group using the external standard method.

[0189] Pesticide removal rate = (1 - pesticide residue in the treatment group / pesticide residue in the blank group) × 100%.

[0190] The test results are shown in Table 1.

[0191] Table 1

[0192] Escherichia coli Bactericidal Rate (%) Fenvalerate Pesticide Removal Rate (%) Heavy Metal Removal Rate (%) Example 1 99.17 86.3 99.62 Example 2 99.28 87.4 99.67 Example 3 99.13 85.7 99.53 Example 4 99.77 90.6 99.82 Example 5 99.81 92.1 99.85 Example 6 99.83 92.8 99.88 Example 7 99.90 93.7 99.87 Example 8 99.85 93.2 99.81 Example 9 94.83 71.2 94.17 Example 10 91.76 65.1 87.92 Example 11 95.38 67.5 93.64 Example 12 90.92 59.8 89.23 Example 13 84.27 54.3 91.85 Example 14 96.49 57.6 83.21 Example 15 89.73 49.8 92.36 Example 16 87.15 47.3 84.78 Example 17 96.34 80.1 96.82 Example 18 95.62 77.5 95.71 Example 19 93.28 81.4 88.45 Example 20 92.76 74.9 85.93

[0193] From the test data of Example 1 and Examples 4-8, it can be seen that the Escherichia coli bactericidal rate, fenvalerate pesticide removal rate, and heavy metal removal rate in Examples 4-8 are slightly lower than those in Example 1. This is because, compared with Example 1, Examples 4-8 newly added mono- and diglycerol fatty acid esters and sodium alginate, which improved the bactericidal performance, pesticide residue removal ability, and heavy metal removal ability of the fruit and vegetable cleaner to a certain extent. This is because, in Examples 4-8, by newly adding mono- and diglycerol fatty acid esters and sodium alginate and optimizing the proportion of each component, the comprehensive improvement of the synergistic effect of multiple components was achieved. In terms of the bactericidal rate, mono- and diglycerol fatty acid esters and sucrose fatty acid esters synergistically damage the bacterial cell membrane (hydrophobic insertion + hydrophilic group interfering with membrane proteins), and the gel network formed by sodium alginate and Ca 2+ can extend the alkaline bacteriostatic time and block microbial activities through physical effects. In terms of the pesticide removal rate, mono- and diglycerol fatty acid esters and sucrose fatty acid esters form a hierarchical emulsification system. Mono- and diglycerol fatty acid esters treat highly hydrophobic pesticides, and sucrose fatty acid esters encapsulate medium-polar pesticide residues. Combined with the sodium alginate gel network to intercept pesticide degradation products and avoid secondary adsorption. In terms of the heavy metal removal rate, the carboxylic acid groups of sodium alginate and nanocellulose construct a dual adsorption network. At the same time, the sodium alginate gel network can delay the precipitation of heavy metal hydroxides and achieve efficient fixation of heavy metal hydroxides.

[0194] From the test data of Example 1, Example 9, and Example 10, it can be seen that the bactericidal rate of Escherichia coli, the removal rate of fenvalerate pesticides, and the removal rate of heavy metals in Example 9 and Example 10 are significantly lower than those in Example 1. This is because in Example 9 and Example 10, the addition amount of nanocellulose powder in the fruit and vegetable cleaning agent was adjusted. The nanocellulose powder is used to form a porous adsorption network to capture pesticide molecules and heavy metal ions through physical adsorption. At the same time, its surface hydroxyl groups coordinate with heavy metals. In Example 9, the addition amount of nanofiber powder is too low, resulting in an incomplete adsorption network; in Example 10, the addition amount of nanofiber powder is too high, causing agglomeration and hindering the reaction interface.

[0195] From the test data of Example 1, Example 11, and Example 12, it can be seen that the bactericidal rate of Escherichia coli, the removal rate of fenvalerate pesticides, and the removal rate of heavy metals in Example 11 and Example 12 are significantly lower than those in Example 1. This is because in Example 11 and Example 12, the addition amount of starch in the fruit and vegetable cleaning agent was adjusted. Starch is used as a dispersion carrier to stabilize nanocellulose, and after swelling, it penetrates into the epidermal wrinkles, and its hydroxyl groups chelate heavy metals. In Example 11, the addition amount of starch is too low, resulting in insufficient viscosity of the cleaning solution, and a decrease in dispersibility and permeability; in Example 12, the addition amount of starch is too high, resulting in the cleaning solution being overly viscous and hindering the diffusion and migration of active ingredients.

[0196] From the test data of Example 1, Example 13, and Example 14, it can be seen that the bactericidal rate of Escherichia coli, the removal rate of fenvalerate pesticides, and the removal rate of heavy metals in Example 13 and Example 14 are significantly lower than those in Example 1. This is because in Example 13 and Example 14, the addition amount of calcium hydroxide in the fruit and vegetable cleaning agent was adjusted. Calcium hydroxide is used to maintain an alkaline environment, decompose the ester bonds of fat-soluble pesticides, precipitate heavy metals, and inhibit bacterial metabolism. In Example 13, the addition amount of calcium hydroxide is too low, resulting in insufficient alkalinity of the cleaning solution, and a deterioration in the hydrolysis of pesticides and antibacterial effects; in Example 14, the addition amount of calcium hydroxide is too high, and the alkalinity of the cleaning solution is too strong, which not only damages the fruit and vegetable epidermis but also causes the precipitation of sucrose fatty acid esters, resulting in the loss of active ingredients.

[0197] From the test data of Example 1, Example 15, and Example 16, it can be seen that the bactericidal rate of Escherichia coli, the removal rate of fenvalerate pesticides, and the removal rate of heavy metals in Example 15 and Example 16 are significantly lower than those in Example 1. This is because in Example 15 and Example 16, the addition amount of sucrose fatty acid ester in the fruit and vegetable cleaning agent was adjusted. Sucrose fatty acid ester, as a biosurfactant, is used to emulsify fat-soluble pesticides and, at the same time, cooperate with mono- and diglycerol fatty acid esters to destroy the bacterial cell membrane. In Example 15, the addition amount of sucrose fatty acid ester is too low, resulting in insufficient emulsification effect on pesticides and a decrease in the pesticide removal rate; in Example 16, the addition amount of sucrose fatty acid ester is too high, and it is easy to react with calcium ions to form precipitates, resulting in the loss of active ingredients.

[0198] From the test data of Example 1, Example 17 and Example 18, it can be seen that the bactericidal rate of Escherichia coli, the removal rate of fenvalerate pesticide and the removal rate of heavy metals in Example 17 and Example 18 are significantly lower than those in Example 1. This is because in Example 17 and Example 18, the mass ratio of sucrose fatty acid ester to mono- and diglycerol fatty acid ester was adjusted. During the cleaning and soaking process, the hydrophobic chain of mono- and diglycerol fatty acid ester inserts into the pesticide molecule and forms a gradient polar micelle in cooperation with sucrose fatty acid ester, enhancing the antibacterial effect. The imbalance of the mass ratio of sucrose fatty acid ester to mono- and diglycerol fatty acid ester in Example 17 and Example 18 results in an unstable micelle structure and a poor pesticide encapsulation effect, ultimately leading to a decrease in the pesticide removal rate.

[0199] From the test data of Example 1, Example 19 and Example 20, it can be seen that the bactericidal rate of Escherichia coli, the removal rate of fenvalerate pesticide and the removal rate of heavy metals in Example 19 and Example 20 are significantly lower than those in Example 1. This is because in Example 19 and Example 20, the mass ratio of calcium hydroxide to sodium alginate was adjusted. Sodium alginate cross-links with Ca 2+ to form a gel network, extending the alkaline action time and intercepting pollutants through physical action. The addition ratio of sodium alginate in Example 9 is too low, resulting in a too loose gel network structure that cannot effectively intercept pollutants; the addition ratio of sodium alginate in Example 20 is too high, resulting in a too dense gel network structure that hinders the diffusion and migration of the active ingredients in the fruit and vegetable cleaner.

[0200] The applicant declares that the above description is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A food-grade fruit and vegetable cleaning agent, characterized in that, The food-grade fruit and vegetable cleaning agent includes nano-cellulose powder, starch, calcium hydroxide, and sucrose fatty acid ester.

2. The food-grade fruit and vegetable cleaning agent according to claim 1, wherein Based on the mass fraction of the food-grade fruit and vegetable cleaning agent being 100 wt%, it includes the following components with the following mass fractions: Nano-cellulose powder 18 - 20 wt%; Starch 50 - 55 wt%; Calcium hydroxide 15 - 20 wt%; Sucrose fatty acid ester 10 - 15 wt%.

3. The food-grade fruit and vegetable cleaning agent according to claim 1, wherein The food-grade fruit and vegetable cleaning agent also includes mono- and diglycerol fatty acid esters.

4. The food-grade fruit and vegetable cleaning agent according to claim 3, wherein The mass ratio of the sucrose fatty acid ester to the mono- and diglycerol fatty acid esters is (3 - 5):

1.

5. The food-grade fruit and vegetable cleaning agent according to claim 1, wherein The food-grade fruit and vegetable cleaning agent also includes sodium alginate.

6. The food-grade fruit and vegetable cleaning agent according to claim 5, wherein, The mass ratio of the calcium hydroxide to the sodium alginate is 1:(0.3 - 0.5).

7. A method for preparing the food-grade fruit and vegetable cleaning agent according to any one of claims 1 to 6, characterized in that, The preparation method includes: Mixing the nano-cellulose powder, starch, calcium hydroxide, and sucrose fatty acid ester evenly in proportion to obtain the food-grade fruit and vegetable cleaning agent.

8. The preparation method according to claim 7, characterized in that, The preparation method includes: Mixing the nano-cellulose powder, starch, calcium hydroxide, sucrose fatty acid ester, mono- and diglycerol fatty acid esters, and sodium alginate evenly in proportion to obtain the food-grade fruit and vegetable cleaning agent.

9. A method for using the food-grade fruit and vegetable cleaning agent according to any one of claims 1 to 6, characterized in that, The usage method includes: Adding the food-grade fruit and vegetable cleaning agent into water, mixing evenly to obtain a cleaning solution; soaking the fruits and vegetables to be cleaned in the cleaning solution, taking them out after soaking for a period of time, and rinsing them clean with clear water.

10. The usage method according to claim 9, wherein, The mixing ratio of the food-grade fruit and vegetable cleaning agent to water is (1.5 - 2.5) g:1 L; The temperature of the water is 30 - 40 °C; The soaking time of the fruits and vegetables to be cleaned in the cleaning solution is 5 - 10 min.

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