Method for treating fresh-cut broccoli through combination of edible composite coating and intermittent superheated steam

Abstract

The invention discloses a method for jointly treating fresh-cut broccoli through edible composite coating and intermittent superheated steam, and belongs to the technical field of agricultural product processing, fresh broccoli is used as a raw material, and the fresh-cut broccoli is obtained through impurity removal, cleaning, cutting, shape finishing, coating, intermittent superheated steam treatment, cooling and packaging. The method is simple in step, short in process period, efficient, energy-saving, green and environment-friendly in operation process, loss of nutrients of the broccoli is reduced through the edible composite coating and intermittent superheated steam treatment, the total color difference of the fresh-cut broccoli is reduced, and the content of total phenols, total anthocyanin, total anthocyanin and total phenolic acid is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of agricultural product processing, and in particular relates to a method for processing fresh-cut broccoli by combining an edible composite coating with intermittent superheated steam. Background Art

[0002] As a non-traditional food processing technology, superheated steam treatment has been proven to have many advantages in food processing, such as high heat transfer coefficient, effective elimination or reduction of microorganisms on the food surface, inhibition of lipid oxidation and harmful compound generation, and improvement of food physical and chemical properties. Superheated steam has strong penetrating power and can destroy the hydrogen bonds inside enzyme molecules, affect enzyme activity, and inhibit enzymatic reactions. Compared with saturated steam, superheated steam treatment can significantly reduce the number of pathogens on the surface of cherry tomatoes and citrus, mainly due to its low humidity environment, which allows the condensate film to evaporate quickly and reduces the protective layer of microorganisms. In addition, the temperature and time of superheated steam treatment need to be precisely controlled to avoid adverse effects on vegetable quality. For example, excessive treatment may cause vegetable tissue softening, affecting taste and nutritional value, which limits its application in the preservation of some foods. Therefore, although superheated steam treatment has significant potential in the preservation of fresh-cut vegetables, its impact on food quality also needs to be considered.

[0003] Edible coatings have been widely used in the preservation of fresh-cut vegetables as an environmentally friendly and effective means of preservation. Such coatings can form a semi-permeable protective barrier, regulate the water and gas exchange between plant tissues and the external environment, and control the physiological metabolic activities of plant tissues, thereby improving the quality of fruits and vegetables after harvest and extending the shelf life. By forming a low O2 / high CO2 gas atmosphere and a high humidity microenvironment, edible coatings can effectively delay the aging of fruits and vegetables after harvest. However, there are also some limitations to coating treatment alone. For example, edible coatings prepared from strongly hydrophobic lipids have poor mechanical properties, are difficult to maintain evenly and stably on the skin of fruits and vegetables, and are easy to penetrate the skin and increase fruit odor. In addition, the insufficient mechanical properties of lipid materials may lead to unstable preservation effects and may cause consumers to worry about their safety. Although coating treatment has a certain effect on the preservation of fresh-cut vegetables, it still needs further improvement and optimization in terms of mechanical properties and consumer acceptance. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a method for treating fresh-cut broccoli by combining an edible composite coating with intermittent superheated steam. The method of the present invention has simple steps, a short process cycle, high efficiency and energy saving in the operation process, and is green and environmentally friendly. The edible composite coating and intermittent superheated steam treatment reduce the loss of nutrients in broccoli, reduce the total color difference of fresh-cut broccoli, and increase the content of total phenols, total anthocyanins, total anthocyanins and total phenolic acids.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for treating fresh-cut broccoli by combining an edible composite coating with intermittent superheated steam, which uses fresh broccoli as a raw material, removes impurities, washes, cuts, trims, coats, treats with intermittent superheated steam, cools and packages to obtain fresh-cut broccoli.

[0007] The present invention uses fresh broccoli as the starting material, and finally obtains a fresh-cut broccoli product with delicious taste and rich nutrition through impurity removal, cleaning, cutting, morphological trimming, coating, intermittent superheated steam treatment, cooling and packaging. The method of the present invention significantly reduces the loss of active substances and quality reduction of fresh-cut broccoli by coupling coating with superheated steam. Compared with single superheated steam treatment, the combined treatment method of the present invention reduces the total color difference of fresh-cut broccoli by 26.02%, increases the total phenol content by 51.92%, increases the total anthocyanin content by 18.90%, and increases the total phenolic acid content by 50.30%. In addition, the operation process of this method is safe, efficient, green and environmentally friendly, and provides a new preservation method for the processing of fresh-cut vegetables.

[0008] Preferably, the method for treating fresh-cut broccoli by combining the edible composite coating with intermittent superheated steam comprises the following steps:

[0009] Remove the outer leaves, impurities and withered parts of the broccoli, and keep the florets and part of the tender stems;

[0010] Wash the broccoli after the above treatment, and drain the water after washing;

[0011] Cut the broccoli, making sure each bud or piece is intact and uniform in size;

[0012] Trim the cut broccoli to remove any stumps, irregular parts, and broken parts;

[0013] Soaking the trimmed broccoli in the edible composite coating liquid to evenly distribute the edible composite coating liquid on the surface of the broccoli, taking out and drying naturally in a cool place;

[0014] The coated broccoli is treated with intermittent superheated steam. After treatment, the broccoli is cooled and vacuum packed.

[0015] Preferably, the broccoli is of uniform maturity, complete appearance, bright green color, and free from pests and diseases and mechanical damage.

[0016] Preferably, the present invention does not limit the way of cutting broccoli, as long as it can ensure that each flower bud or block is intact and uniform in size after cutting. For example, using the QC-112 model multifunctional double-head vegetable cutter, by replacing different knives and adjusting cutting parameters, the broccoli can be accurately cut to ensure that each flower bud or block is intact and uniform in size. When cutting broccoli, it is advisable to meet the needs of different consumption scenarios. For example, cut the broccoli into 1×1×1cm 3 3×3×3cm 3 and 5×5×5cm 3 a specific size.

[0017] Preferably, the edible composite coating liquid consists of cinnamaldehyde nanoemulsion, chitosan solution and carrageenan solution.

[0018] Preferably, the volume ratio of the cinnamaldehyde nanoemulsion, the chitosan solution and the carrageenan solution is 5:1:4.

[0019] Preferably, the preparation method of the cinnamaldehyde nanoemulsion is:

[0020] Tween-80 and anhydrous ethanol were mixed in a mass ratio of 2:1 to obtain a mixture A;

[0021] The mixture A is mixed with ethyl acetate in a mass ratio of 11:9 to obtain a mixture B;

[0022] Under stirring, water is added dropwise to the mixture B until a blank nanoemulsion is formed;

[0023] Under stirring conditions, cinnamaldehyde is added dropwise to the blank nanoemulsion until cinnamaldehyde is no longer dissolved, thereby obtaining the cinnamaldehyde nanoemulsion. The cinnamaldehyde nanoemulsion of the present invention is prepared under room temperature conditions.

[0024] Preferably, the mass concentration of the chitosan solution is 1%, and the mass concentration of the carrageenan solution is 5%.

[0025] Preferably, the trimmed broccoli is immersed in the edible composite coating liquid for 5 minutes.

[0026] Preferably, during the intermittent superheated steam treatment, the superheated steam treatment temperature is 100-160°C. The above-mentioned superheated steam treatment temperature is moderate, which can effectively kill microorganisms and maintain the nutritional components and taste of broccoli.

[0027] Preferably, the superheated steam treatment temperature is 100°C, 120°C, 140°C or 160°C.

[0028] Preferably, the intermittent superheated steam treatment step is: first sending the coated broccoli into a superheated steam treatment device for heating for 2-4 minutes, taking it out and cooling it, and then heating it for the same time.

[0029] More preferably, the time of the intermittent superheated steam treatment is 2 min, 3 min or 4 min.

[0030] The present invention uses intermittent superheated steam to treat the coated broccoli, which can significantly improve the color, juiciness, texture, flavor and sweetness of the broccoli. The color, juiciness, texture, flavor and sweetness scores are higher than those of untreated broccoli. The hardness of the broccoli can also be reduced, making the broccoli taste better. In short, after being treated by the method of the present invention, the loss of nutrients in the broccoli is reduced, the juiciness is increased, more sugar is retained, and the antioxidant activity of the broccoli is improved. The sensory quality and nutritional value of the broccoli can be effectively improved, and the taste and utilization rate of the nutrients are improved.

[0031] Preferably, the cooling is cooling the broccoli to 4°C.

[0032] More preferably, the method for treating fresh-cut broccoli by combining the edible composite coating with intermittent superheated steam is:

[0033] Step 1: Raw material selection: Choose broccoli with uniform maturity, intact appearance, bright green color, and no pests or mechanical damage as processing raw materials to ensure the overall quality of the product;

[0034] Step 2: Remove impurities: Place the selected broccoli on the workbench, remove the outer leaves, impurities and withered parts, and keep the flower heads and some tender stems;

[0035] Step 3: Washing: Place the selected broccoli after removing impurities in clean running water for thorough washing to remove dirt, pesticide residues and impurities on the surface, and drain the water after washing;

[0036] Step 4: Precision cutting: Use the QC-112 multi-function double-head vegetable cutter to achieve precise cutting of broccoli by changing different knives and adjusting cutting parameters, ensuring that each bud or block is intact and uniform in size;

[0037] Step 5: Trim the shape: Trim the cut broccoli to remove the remaining roots, irregular parts and damaged parts to make it more beautiful and neat;

[0038] Step 6: preparing an edible composite coating liquid: mixing the cinnamaldehyde nanoemulsion, 1 wt% chitosan solution and 5 wt% carrageenan solution in a volume ratio of 5:1:4 to prepare an edible composite coating liquid;

[0039] Step 7: coating treatment: soak the fresh-cut broccoli in the prepared edible composite coating liquid for 5 minutes, so that the edible composite coating liquid is evenly distributed on the surface of the broccoli, and then take it out and dry it naturally in a cool place;

[0040] Step 8: Equipment preheating: Preheat the superheated steam equipment to 120°C to ensure that the steam temperature is moderate, which can effectively kill microorganisms while maintaining the nutritional content and taste of broccoli;

[0041] Step 9: Intermittent superheated steam treatment: The cut broccoli is first sent to the superheated steam treatment equipment, the temperature of the superheated steam is controlled at 100-160°C, and it is heated for 2-4 minutes. After being taken out and cooled, it is heated again for the same time to achieve the best processing effect and product quality (that is, the total time of intermittent superheated steam treatment is 4-8 minutes);

[0042] Step 10: Cooling and packaging: After processing, the broccoli is quickly cooled to a suitable temperature to avoid excessive heat damage. It is then vacuum-packed to ensure the freshness and safety of the product during transportation and storage.

[0043] Compared with continuous superheated steam treatment, intermittent superheated steam treatment can more accurately control the treatment process through periodic heating and cooling, especially in fresh-cut vegetables that are sensitive to temperature and humidity. This treatment method can reduce the negative effects on food quality, such as color change and tissue softening. In addition, due to its periodic characteristics, intermittent superheated steam treatment can better regulate and control the inactivation effect of microorganisms during the treatment process, especially when inactivating microorganisms on the surface of food. Intermittent treatment can reduce food quality problems that may be caused by superheated steam treatment. Cinnamaldehyde is derived from natural plants and is favored for its easy access, low toxicity and wide range of pharmacological activities, including anti-inflammatory, antibacterial, anticancer and anti-diabetic. Cinnamaldehyde nanoemulsion effectively reduces the water vapor permeability of the coating through antibacterial and antioxidant properties, thereby extending the shelf life of broccoli. Chitosan, as a natural polysaccharide with antibacterial properties, can form a protective film after being compounded with nanoemulsion, which is coated on the surface of food to prevent the invasion of oxygen, moisture and microorganisms, and effectively delay the spoilage of food. The synergistic effect of cinnamaldehyde and chitosan not only enhances the preservation effect, improves food safety and nutritional value, but also improves the thermal stability of chitosan and provides an efficient preservation strategy for broccoli storage through controlled release.

[0044] The combined treatment method of edible composite coating and intermittent superheated steam proposed in the present invention can combine the advantages of both, utilizing both the efficient sterilization and enzyme inactivation effects of superheated steam and the protective barrier and physiological metabolism regulating functions of the coating to achieve better preservation of fresh-cut vegetables. Compared with continuous treatment, intermittent superheated steam treatment can more accurately control the treatment process and reduce negative impacts on food quality, such as color changes and tissue softening, while maintaining the efficient sterilization characteristics of superheated steam treatment. The combined treatment method of the present invention can not only improve the taste and nutritional value of broccoli, but also effectively extend the shelf life and achieve better preservation effects.

[0045] The composite coating liquid composed of cinnamaldehyde nanoemulsion, chitosan solution and carrageenan solution in the present invention is not only resistant to high temperature, but also can be more tightly wrapped on the surface of broccoli under the action of superheated steam, thereby enhancing the protective effect of the coating. Secondly, the constituent materials of this composite coating liquid have good biocompatibility and biodegradability, ensuring food safety. In addition, the addition of cinnamaldehyde significantly improves the antibacterial properties of the coating, while the broad-spectrum antibacterial property of chitosan further enhances the safety and nutritional value of food. Through this combined treatment method, the shelf life of broccoli is effectively extended while maintaining its quality, which is an efficient, energy-saving and environmentally friendly food processing technology. In addition, the edible coating uses the semi-permeable protective barrier formed by itself to place the fruits and vegetables wrapped in the film in a low O2 / high CO2 gas atmosphere and a high humidity microenvironment, thereby controlling various physiological metabolic activities of plant tissues, improving the quality of fruits and vegetables after harvest, and extending the shelf life. In summary, the present invention solves multiple technical problems existing in traditional preservation technology through innovative coating materials and treatment methods, and provides a new solution for the preservation of fresh-cut broccoli.

[0046] Compared with the prior art, the present invention has the following advantages and technical effects:

[0047] 1. The method of the present invention significantly improves the quality and nutrient retention of fresh-cut broccoli by optimizing the processing method of fresh-cut vegetables. Compared with a single superheated steam treatment, the combined treatment method of the present invention reduces the total color difference of fresh-cut broccoli by 26.02%, increases the total phenol content by 51.92%, increases the total anthocyanin content by 18.90%, and increases the total phenolic acid content by 50.30%. These improvements not only enhance the health benefits of broccoli, but also enrich its flavor.

[0048] 2. The composite coating liquid composed of cinnamaldehyde nanoemulsion, chitosan solution and carrageenan solution in the present invention is not only resistant to high temperature, but also can be more tightly wrapped on the surface of broccoli under the action of superheated steam, thereby enhancing the protective effect of the coating. Secondly, the constituent materials of this composite coating liquid have good biocompatibility and biodegradability, ensuring food safety. In addition, the addition of cinnamaldehyde significantly improves the antibacterial properties of the coating, while the broad-spectrum antibacterial property of chitosan further enhances the safety and nutritional value of food.

[0049] 3. The processing process of the present invention is simple and easy, which effectively reduces energy consumption and production costs, and provides strong technical support for the commercial production of fresh-cut broccoli. This innovative method not only improves production efficiency, but also promotes its wide application in the food industry, bringing a healthier and more nutritious fresh-cut vegetable option to the market. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0051] Figure 1 Fresh-cut 5×5×5 cm cubes were processed with different superheated steam temperatures and times in Example 1 to Example 12. 3 Changes in total phenolics in broccoli, where 0min represents fresh broccoli without any treatment;

[0052] Figure 2 Fresh-cut 5×5×5 cm cubes were processed with different superheated steam temperatures and times in Example 1 to Example 12. 3 Changes in total phenolic acids in broccoli, where 0min represents fresh broccoli without any treatment;

[0053] Different lowercase letters indicate significant differences (P<0.05), and the same letters indicate no significant differences (P>0.05). DETAILED DESCRIPTION

[0054] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0055] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0056] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0057] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0058] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0059] Unless otherwise specified, the room temperature in the present invention is 25±2°C.

[0060] All raw materials used in the examples of the present invention are commercially available.

[0061] In the embodiments of the present invention, "fresh broccoli" refers to broccoli that has just been picked.

[0062] In an embodiment of the present invention, the preparation method of cinnamaldehyde nanoemulsion is:

[0063] At room temperature, Tween-80 and anhydrous ethanol were mixed in a mass ratio of 2:1 to obtain a mixture A;

[0064] Mixing mixture A and ethyl acetate in a mass ratio of 11:9 to obtain mixture B;

[0065] Under stirring, distilled water was added dropwise to mixture B until a blank nanoemulsion was formed;

[0066] Under stirring conditions, cinnamaldehyde is added dropwise to the blank nanoemulsion until cinnamaldehyde is no longer dissolved, thereby obtaining cinnamaldehyde nanoemulsion.

[0067] In an embodiment of the present invention, the preparation method of 1 wt % chitosan solution is: fully dissolving chitosan in 6 mol / L hydrochloric acid to obtain 1 wt % chitosan solution.

[0068] In an embodiment of the present invention, the preparation method of 5 wt % carrageenan solution is as follows: 5 g carrageenan is dissolved in 95 mL deionized water, and stirred evenly to obtain 5 wt % carrageenan solution.

[0069] In the present invention, the method of cutting broccoli is not limited, as long as each bud or block is intact and uniform in size after cutting. When cutting broccoli, it is appropriate to meet the needs of different consumption scenarios. For example, broccoli is cut into 1×1×1cm 3 3×3×3cm 3 and 5×5×5cm 3 In some typical embodiments of the present invention, a QC-112 multifunctional double-head vegetable cutter is used to achieve precise cutting of broccoli by replacing different knives and adjusting cutting parameters, and the broccoli is cut into 5×5×5 cm 3 , making sure each bud or clump is complete and uniform in size.

[0070] It should be pointed out that the matters not described in detail in the present invention are conventional operating means in the art and are not the focus of the present invention.

[0071] The technical solution of the present invention is further illustrated by the following embodiments.

[0072] Example 1

[0073] Step 1: Raw material selection: Choose broccoli with uniform maturity, intact appearance, bright green color, and no pests or mechanical damage as processing raw materials to ensure the overall quality of the product;

[0074] Step 2: Remove impurities: Place the selected broccoli on the workbench, remove the outer leaves, impurities and withered parts, and keep the flower heads and some tender stems;

[0075] Step 3: Washing: Place the selected broccoli after removing impurities in clean running water for thorough washing to remove dirt, pesticide residues and impurities on the surface, and drain the water after washing;

[0076] Step 4: Precision cutting: Use the QC-112 multi-function double-head vegetable cutter to accurately cut the broccoli into 5×5×5cm pieces by changing different knives and adjusting the cutting parameters. 3Size, ensuring that each bud or clump is intact and uniform in size;

[0077] Step 5: Trim the shape: Trim the cut broccoli to remove the remaining roots, irregular parts and damaged parts to make it more beautiful and neat;

[0078] Step 6: preparing an edible composite coating liquid: mixing the cinnamaldehyde nanoemulsion, 1 wt% chitosan solution and 5 wt% carrageenan solution in a volume ratio of 5:1:4 to prepare an edible composite coating liquid;

[0079] Step 7: coating treatment: soak the fresh-cut broccoli in the prepared edible composite coating liquid for 5 minutes, so that the edible composite coating liquid is evenly distributed on the surface of the broccoli, and then take it out and dry it naturally in a cool place;

[0080] Step 8: Equipment preheating: Preheat the superheated steam equipment to 120°C to ensure that the steam temperature is moderate, which can effectively kill microorganisms while maintaining the nutritional content and taste of broccoli;

[0081] Step 9: Intermittent superheated steam treatment: The cut broccoli is first sent into the superheated steam treatment equipment for heating for 2 minutes, then taken out and placed on ice for 2 minutes and heated again for 2 minutes to achieve the best processing effect and product quality;

[0082] Step 10: Cooling and packaging: After processing, the broccoli is quickly cooled to 4°C to avoid excessive heat damage, and then vacuum-packed to ensure the freshness and safety of the product during transportation and storage.

[0083] Comparative Example 1: Intermittent Superheated Steam Treatment

[0084] The same as Example 1, the only difference is that step 6 and step 7 are omitted. That is, in this comparative example, the cut broccoli is directly subjected to intermittent superheated steam treatment.

[0085] Comparative Example 2 Edible Composite Coating Treatment Alone

[0086] The same as Example 1, the only difference is that step 8 and step 9 are omitted. That is, in this comparative example, the broccoli after the coating treatment is directly cooled and packaged.

[0087] Comparative Example 3 Edible coating combined with continuous superheated steam treatment

[0088] The same as Example 1, except that step 9 is replaced by continuous superheated steam treatment: the cut broccoli is first sent to the superheated steam treatment equipment, and is quickly processed by high-temperature and high-pressure superheated steam. The temperature of the superheated steam is controlled at 120°C, and the heating time is 4 minutes.

[0089] The results of the effects of the nutritional substances (total color difference, total phenols, total anthocyanins, and total phenolic acid content) of fresh-cut broccoli after treatment with Example 1 and Comparative Examples 1 to 3 are shown in Table 1.

[0090] Table 1

[0091]

[0092] As can be seen from Table 1, compared with Comparative Example 1, Example 1 proves that the broccoli treated with edible coating combined with intermittent superheated steam has a total color difference reduced by 26.02%, a total phenol content increased by 51.92%, a total anthocyanin content increased by 18.90%, and a total phenolic acid content increased by 50.30% compared with the broccoli treated with superheated steam alone; compared with the single coating treatment (Comparative Example 2), the total color difference is reduced by 23.26%, the total phenol content is increased by 58.80%, the total anthocyanin content is increased by 8.61%, and the total phenolic acid content is increased by 34.79%; compared with the combined treatment of edible composite coating and continuous superheated steam (Comparative Example 3), the total color difference is reduced by 26.93%, the total phenol content is increased by 15.31%, the total anthocyanin content is increased by 8.66%, and the total phenolic acid content is increased by 3.43%.

[0093] Example 2

[0094] Step 1: Raw material selection: Choose broccoli with uniform maturity, intact appearance, bright green color, and no pests or mechanical damage as processing raw materials to ensure the overall quality of the product;

[0095] Step 2: Remove impurities: Place the selected broccoli on the workbench, remove the outer leaves, impurities and withered parts, and keep the flower heads and some tender stems;

[0096] Step 3: Washing: Place the selected broccoli after removing impurities in clean running water for thorough washing to remove dirt, pesticide residues and impurities on the surface, and drain the water after washing;

[0097] Step 4: Precision cutting: Use the QC-112 multi-function double-head vegetable cutter to accurately cut the broccoli into 5×5×5cm pieces by changing different knives and adjusting the cutting parameters. 3 Size, ensuring that each bud or clump is intact and uniform in size;

[0098] Step 5: Trim the shape: Trim the cut broccoli to remove the remaining roots, irregular parts and damaged parts to make it more beautiful and neat;

[0099] Step 6: preparing an edible composite coating liquid: mixing the cinnamaldehyde nanoemulsion, 1 wt% chitosan solution and 5 wt% carrageenan solution in a volume ratio of 5:1:4 to prepare an edible composite coating liquid;

[0100] Step 7: coating treatment: soak the fresh-cut broccoli in the prepared edible composite coating liquid for 5 minutes, so that the edible composite coating liquid is evenly distributed on the surface of the broccoli, and then take it out and dry it naturally in a cool place;

[0101] Step 8: Equipment preheating: Preheat the superheated steam equipment to 120°C to ensure that the steam temperature is moderate, which can effectively kill microorganisms while maintaining the nutritional content and taste of broccoli;

[0102] Step 9: Intermittent superheated steam treatment: The cut broccoli is first sent into the superheated steam treatment equipment for heating for 3 minutes, then taken out and placed on ice for 2 minutes and heated again for 3 minutes to achieve the best processing effect and product quality;

[0103] Step 10: Cooling and packaging: After processing, the broccoli is quickly cooled to 4°C to avoid excessive heat damage, and then vacuum-packed to ensure the freshness and safety of the product during transportation and storage.

[0104] The results of the effects on the nutrients (total color difference, total phenols, total anthocyanins, and total phenolic acid content) of fresh-cut broccoli after treatment in this example are shown in Table 2.

[0105] Table 2

[0106]

[0107] Example 3

[0108] Step 1: Raw material selection: Choose broccoli with uniform maturity, intact appearance, bright green color, and no pests or mechanical damage as processing raw materials to ensure the overall quality of the product;

[0109] Step 2: Remove impurities: Place the selected broccoli on the workbench, remove the outer leaves, impurities and withered parts, and keep the flower heads and some tender stems;

[0110] Step 3: Washing: Place the selected broccoli after removing impurities in clean running water for thorough washing to remove dirt, pesticide residues and impurities on the surface, and drain the water after washing;

[0111] Step 4: Precision cutting: Use the QC-112 multi-function double-head vegetable cutter to accurately cut the broccoli into 5×5×5cm pieces by changing different knives and adjusting the cutting parameters. 3 Size, ensuring that each bud or clump is intact and uniform in size;

[0112] Step 5: Trim the shape: Trim the cut broccoli to remove the remaining roots, irregular parts and damaged parts to make it more beautiful and neat in shape;

[0113] Step 6: preparing an edible composite coating liquid: mixing the cinnamaldehyde nanoemulsion, 1 wt% chitosan solution and 5 wt% carrageenan solution in a volume ratio of 5:1:4 to prepare an edible composite coating liquid;

[0114] Step 7: coating treatment: soak the fresh-cut broccoli in the prepared edible composite coating liquid for 5 minutes, so that the edible composite coating liquid is evenly distributed on the surface of the broccoli, and then take it out and dry it naturally in a cool place;

[0115] Step 8: Equipment preheating: Preheat the superheated steam equipment to 140°C to ensure that the steam temperature is moderate, which can effectively kill microorganisms while maintaining the nutritional content and taste of broccoli;

[0116] Step 9: Intermittent superheated steam treatment: The cut broccoli is first sent into the superheated steam treatment equipment for heating for 2 minutes, then taken out and placed on ice for 2 minutes and heated again for 2 minutes to achieve the best processing effect and product quality;

[0117] Step 10: Cooling and packaging: After processing, the broccoli is quickly cooled to 4°C to avoid excessive heat damage, and then vacuum-packed to ensure the freshness and safety of the product during transportation and storage.

[0118] The results of the effects of the treatment on the nutrients (total color difference, total phenols, total anthocyanins, and total phenolic acid content) of fresh-cut broccoli after treatment in this example are shown in Table 3.

[0119] Table 3

[0120]

[0121]

[0122] Comparative Example 4: Single coating combined with intermittent superheated steam treatment

[0123] The only difference from Example 1 is that the edible coating liquid in step 6 is only a chitosan solution (1 wt %), and the other parameters and conditions are the same as those in Example 1.

[0124] The results of the effects on the nutritional substances (total color difference, total phenols, total anthocyanins, and total phenolic acid content) of fresh-cut broccoli after treatment in this comparative example are shown in Table 4.

[0125] Table 4

[0126]

[0127] As shown in Table 4, compared with Example 1, the total color difference of the single coating combined with intermittent superheated steam treatment increased by 36.65%, the total phenol content decreased by 45.42%, the total anthocyanin content decreased by 19.66%, and the total phenolic acid content decreased by 38.36%. Compared with the combined treatment of chitosan coating alone and the combined treatment of composite coating, the water vapor permeability of pure chitosan film is high and the oxygen permeability is difficult to adjust, resulting in poor moisture retention, poor toughness and moisture retention after film formation. In addition, the antioxidant activity of pure chitosan is basically zero, while in the edible composite coating liquid, cinnamaldehyde nanoemulsion effectively reduces the water vapor permeability of the coating through its antibacterial and antioxidant properties, thereby extending the shelf life of fruits and vegetables. The synergistic effect of cinnamaldehyde and chitosan enhances the preservation effect of fresh-cut broccoli and improves safety and nutritional value.

[0128] Example 4

[0129] Same as Example 1, except that step 9 is: intermittent superheated steam treatment: the cut broccoli is first sent into the superheated steam treatment equipment for heating for 4 minutes, then taken out and placed on the ice for 2 minutes and heated again for 4 minutes to achieve the best processing effect and product quality.

[0130] Example 5

[0131] Same as Example 1, except that step 8 is: Equipment preheating: preheat the superheated steam equipment to 100° C. to ensure that the steam temperature is moderate, which can effectively kill microorganisms and maintain the nutritional components and taste of the broccoli.

[0132] Example 6

[0133] The same as Example 1, except that step 8 is: equipment preheating: preheating the superheated steam equipment to 100°C to ensure that the steam temperature is moderate, which can effectively kill microorganisms and maintain the nutritional components and taste of the broccoli; step 9 is: intermittent superheated steam treatment: the cut broccoli is first sent to the superheated steam treatment equipment for heating for 3 minutes, and then placed on the ice for 2 minutes after taking it out and heated again for 3 minutes to achieve the best processing effect and product quality.

[0134] Example 7

[0135] The same as Example 1, except that step 8 is: equipment preheating: preheating the superheated steam equipment to 100°C to ensure that the steam temperature is moderate, which can effectively kill microorganisms and maintain the nutritional components and taste of the broccoli; step 9 is: intermittent superheated steam treatment: the cut broccoli is first sent to the superheated steam treatment equipment for heating for 4 minutes, then taken out and placed on the ice for 2 minutes and heated again for 4 minutes to achieve the best processing effect and product quality.

[0136] Example 8

[0137] The same as Example 1, except that step 8 is: equipment preheating: preheating the superheated steam equipment to 140°C to ensure that the steam temperature is moderate, which can effectively kill microorganisms and maintain the nutritional components and taste of the broccoli; step 9 is: intermittent superheated steam treatment: the cut broccoli is first sent to the superheated steam treatment equipment for heating for 3 minutes, then taken out and placed on the ice for 2 minutes and heated again for 3 minutes to achieve the best processing effect and product quality.

[0138] Example 9

[0139] The same as Example 1, except that step 8 is: equipment preheating: preheating the superheated steam equipment to 140°C to ensure that the steam temperature is moderate, which can effectively kill microorganisms and maintain the nutritional components and taste of the broccoli; step 9 is: intermittent superheated steam treatment: the cut broccoli is first sent to the superheated steam treatment equipment for heating for 4 minutes, then taken out and placed on the ice for 2 minutes and heated again for 4 minutes to achieve the best processing effect and product quality.

[0140] Example 10

[0141] The same as Example 1, except that step 8 is: equipment preheating: preheating the superheated steam equipment to 160°C to ensure that the steam temperature is moderate, which can effectively kill microorganisms and maintain the nutritional components and taste of the broccoli; step 9 is: intermittent superheated steam treatment: the cut broccoli is first sent to the superheated steam treatment equipment for heating for 2 minutes, then taken out and placed on the ice for 2 minutes and heated again for 2 minutes to achieve the best processing effect and product quality.

[0142] Embodiment 11

[0143] The same as Example 1, except that step 8 is: equipment preheating: preheating the superheated steam equipment to 160°C to ensure that the steam temperature is moderate, which can effectively kill microorganisms and maintain the nutritional components and taste of the broccoli; step 9 is: intermittent superheated steam treatment: the cut broccoli is first sent to the superheated steam treatment equipment for heating for 3 minutes, then taken out and placed on the ice for 2 minutes and heated again for 3 minutes to achieve the best processing effect and product quality.

[0144] Example 12

[0145] The same as Example 1, except that step 8 is: equipment preheating: preheating the superheated steam equipment to 160°C to ensure that the steam temperature is moderate, which can effectively kill microorganisms and maintain the nutritional components and taste of the broccoli; step 9 is: intermittent superheated steam treatment: the cut broccoli is first sent to the superheated steam treatment equipment for heating for 4 minutes, then taken out and placed on the ice for 2 minutes and heated again for 4 minutes to achieve the best processing effect and product quality.

[0146] Different superheated steam temperatures and times in Example 1-Example 12 were used to treat fresh-cut 5×5×5 cm 3 The changes in total phenol content of broccoli are shown in Figure 1 , the change of total phenolic acid is shown in Figure 2 It can be seen that the total phenol content first increases and then decreases with the increase of superheated steam temperature, reaching the highest value (15.04 mg / g) when heated at 120℃ for 4 minutes. The total phenolic acid content also first increases and then decreases with the increase of temperature. The total phenolic acid of broccoli heated at 120℃ is the highest. This is because the phenolic compounds of broccoli exist in a soluble form combined with cell wall complexes. Under normal circumstances, the higher the temperature, the faster the degradation of phenolic substances, but it is also conducive to destroying the cell membrane and causing the phenolic substances to flow out; the longer the treatment time, the less conducive it is to the retention of phenolic substances. Therefore, moderate intermittent superheated steam temperature and time treatment (120℃, 4min), combined with composite coating, makes the total phenol and total phenolic acid content at the highest point.

[0147] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for treating fresh-cut broccoli by combining an edible composite coating with intermittent superheated steam, characterized in that: Fresh broccoli is used as a raw material, and is subjected to the steps of impurity removal, cleaning, cutting, shape trimming, film coating, intermittent superheated steam treatment, cooling and packaging to obtain fresh-cut broccoli.

2. The method for treating fresh-cut broccoli by combining an edible composite coating with intermittent superheated steam according to claim 1, characterized in that: The following steps are involved: Remove the outer leaves, impurities and withered parts of the broccoli, and keep the florets and part of the tender stems; Wash the broccoli after the above treatment, and drain the water after washing; Cut the broccoli, making sure each bud or piece is intact and uniform in size; Trim the cut broccoli to remove any stumps, irregular parts, and broken parts; Soaking the trimmed broccoli in the edible composite coating liquid to evenly distribute the edible composite coating liquid on the surface of the broccoli, taking out and drying naturally in a cool place; The coated broccoli is treated with intermittent superheated steam. After treatment, the broccoli is cooled and vacuum packed.

3. The method for treating fresh-cut broccoli by combining an edible composite coating with intermittent superheated steam according to claim 2, characterized in that: The edible composite coating liquid consists of cinnamaldehyde nanoemulsion, chitosan solution and carrageenan solution.

4. The method for treating fresh-cut broccoli by combining an edible composite coating with intermittent superheated steam according to claim 3, characterized in that: The volume ratio of the cinnamaldehyde nanoemulsion, the chitosan solution and the carrageenan solution is 5:1:

4.

5. The method for treating fresh-cut broccoli by combining an edible composite coating with intermittent superheated steam according to claim 4, characterized in that: The preparation method of the cinnamaldehyde nanoemulsion is: Tween-80 and anhydrous ethanol were mixed in a mass ratio of 2:1 to obtain a mixture A; The mixture A is mixed with ethyl acetate in a mass ratio of 11:9 to obtain a mixture B; Under stirring, water is added dropwise to the mixture B until a blank nanoemulsion is formed; Under stirring conditions, cinnamaldehyde is added dropwise to the blank nanoemulsion until cinnamaldehyde is no longer dissolved, thereby obtaining the cinnamaldehyde nanoemulsion.

6. The method for treating fresh-cut broccoli by combining an edible composite coating with intermittent superheated steam according to claim 4, characterized in that: The mass concentration of the chitosan solution is 1%, and the mass concentration of the carrageenan solution is 5%.

7. The method for treating fresh-cut broccoli by combining an edible composite coating with intermittent superheated steam according to claim 2, characterized in that: During the intermittent superheated steam treatment, the superheated steam treatment temperature is 100-160°C.

8. The method for treating fresh-cut broccoli by combining an edible composite coating with intermittent superheated steam according to claim 7, characterized in that: The superheated steam treatment temperature is 100°C, 120°C, 140°C or 160°C.

9. The method for treating fresh-cut broccoli by combining an edible composite coating with intermittent superheated steam according to claim 2, characterized in that: The steps of the intermittent superheated steam treatment are: first sending the coated broccoli into the superheated steam treatment equipment for heating for 2-4 minutes, taking it out and cooling it, and then heating it for the same time.

10. The method for treating fresh-cut broccoli by combining an edible composite coating with intermittent superheated steam according to claim 1, characterized in that: The cooling is to cool the broccoli to 4°C.

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