A composite coating solution that reduces grease penetration and its preparation method

Abstract

This invention relates to the field of coating technology for fried foods, and in particular to a composite coating solution that reduces oil penetration and its preparation method, comprising the following steps: Step a1: Preparation of whey protein mother liquor: Weigh whey protein powder and dissolve it in deionized water, stir until completely dissolved at room temperature, and then hydrate in a refrigerator to obtain a protein solution; Step a2: Preparation of sodium alginate mother liquor: Weigh sodium alginate powder and dissolve it in deionized water, stir until completely dissolved at room temperature, and then hydrate in a refrigerator to obtain a sodium alginate solution; Step a3: Mix the whey protein solution and sodium alginate solution obtained in steps a1 and a2, and adjust the pH of the mixed solution to 4.5-3.5 under stirring to obtain the composite coating solution. The composite coating solution of this invention forms a barrier during frying, which helps to reduce moisture loss and effectively prevents oil from penetrating the food, thereby reducing the greasiness of fried foods and improving their taste and flavor.

Description

Technical Field

[0001] This invention relates to the field of coating technology for fried foods, and in particular to a composite coating solution that can reduce oil penetration and its preparation method. Background Technology

[0002] Fried foods are loved by consumers for their unique flavor, appealing color, and distinctive taste. However, the high oil content of fried foods not only affects their quality but also produces carcinogens such as acrylamide at high temperatures. Excessive consumption can lead to cardiovascular disease, high blood pressure, obesity, and cancer. Therefore, with the increasing demand for low-fat and low-calorie healthy foods, reducing the oil content of fried foods is particularly important.

[0003] Currently, research on reducing the oil content of fried foods is ongoing to improve their quality and health benefits, and various improvement technologies have been extensively studied. Some studies indicate that methods such as oil substitution, vacuum frying, microwave frying, and coating techniques can significantly reduce the oil content of fried foods without significantly affecting their taste and texture. Vacuum frying, supercritical fluid frying, and oil coating technologies can reduce the amount of oil absorbed by ingredients, thus decreasing the oil content. Coating techniques can improve the appearance and taste of fried foods, reduce oil penetration, and enhance product quality and flavor; this method requires no complex machinery, is inexpensive, and easy to operate. Auxiliary materials and additives, such as antioxidants, enzymes, and cellulose, can alter the texture, taste, and nutritional value of fried foods. Low-temperature frying technology can reduce oil quality changes during the frying process, thereby improving the health benefits of fried foods.

[0004] Currently, there is limited research on composite coatings for oil-reducing coatings used in fried foods, and few studies have established a link between coating structural characteristics and oil-reducing mechanisms, resulting in a lack of in-depth research and application of frying coatings.

[0005] Chinese patent CN 1919023 B discloses an oil improver that can reduce the fat content in fried foods. The coating method uses a mixture of starch and oil modified with reagents of octenyl succinic anhydride, dodecene succinic anhydride, and mixtures thereof. This method treats the coating material with chemical reagents and also adds oil, which may increase the adverse effects during the frying process.

[0006] Chinese patent CN 111838565 A discloses a protein composite edible coating for fried foods and its preparation method. In this method, the content of plasma protein powder is 8% (w / w), the content of egg white protein powder is 3% (w / w), and the amount of glycerol added is 20% of the total mass of protein powder and egg white protein powder. This method has a lot of coating raw materials and a slightly higher protein concentration, which may result in higher costs. It also does not explain the relationship between the structural characteristics of the coating and oil reduction, and does not solve the essential problem of oil reduction. Summary of the Invention

[0007] The purpose of this invention is to provide a composite coating solution that can reduce grease penetration and its preparation method, thereby solving the above-mentioned technical problems.

[0008] This invention provides a method for preparing a composite coating solution that can reduce grease penetration, comprising the following steps:

[0009] Step a1: Preparation of whey protein stock solution: Weigh whey protein powder and dissolve it in deionized water. Stir until completely dissolved at room temperature, then place in a refrigerator to hydrate and obtain a protein solution.

[0010] Step a2: Preparation of sodium alginate mother liquor: Weigh sodium alginate powder and dissolve it in deionized water. Stir until completely dissolved at room temperature, then place it in a refrigerator to hydrate and obtain sodium alginate solution.

[0011] Step a3: Mix the whey protein solution and sodium alginate solution obtained in steps a1 and a2, and adjust the pH of the mixed solution to 4.5-3.5 under stirring to obtain the composite coating solution.

[0012] Preferably, the concentration of the whey protein solution in step a1 is 20 mg / ml.

[0013] Preferably, the concentration of sodium alginate solution in step a2 is 10 mg / ml.

[0014] Preferably, in step a3, NaOH solution and hydrochloric acid are used to adjust the pH value of the mixed solution, and the concentration of both NaOH solution and hydrochloric acid is 0.5 mol / L.

[0015] Preferably, in step a3, the pH of the mixed solution is adjusted to 3.5.

[0016] The present invention also provides a composite coating solution that can reduce grease penetration, prepared according to the preparation method described above.

[0017] The present invention also provides a method for frying French fries using the above-mentioned composite coating solution, comprising the following steps:

[0018] Step b1: Wash the potatoes thoroughly and cut them into 1*1*5cm potato strips using a strip cutter. Blanch the potato strips at 95℃ for 4 minutes to inactivate enzymes, remove surface starch, and gelatinize the starch. Then cool them in running cold water for 1 minute to room temperature and wipe off excess moisture with paper towels.

[0019] Step b2: Immerse the potato strips prepared in step b1 in the composite coating solution, then remove them and place them on the wire mesh to drain excess solution from the surface.

[0020] Step b3: Fry the potato fries obtained in step b2 in a deep fryer containing soybean oil. After frying, place the fries on a wire mesh to cool for 10 minutes and drain off excess oil.

[0021] Preferably, in step b2, the ratio of the mass of the potato strips to the volume of the composite coating solution (g:ml) is 1:4; and the soaking time is 5 minutes.

[0022] Preferably, the frying temperature in step b3 is 150°C.

[0023] Preferably, in step b3, the volume ratio of oil to the mass of potato strips (ml:g) is 25:1.

[0024] The beneficial effects of this invention are:

[0025] The composite coating solution of this invention forms a barrier during frying, which helps reduce moisture loss, maintains the moist and tender texture of fried foods, and prevents over-frying from causing the food to dry out. It effectively prevents oil from penetrating into the ingredients, reduces oil absorption, thereby reducing the greasiness of fried foods and improving their taste and flavor. Through the characteristics of the composite whey protein-sodium alginate coating, it endows the ingredients with better properties, improves the appearance, color, and taste of fried foods, enhances their quality and taste, and increases their nutritional value. Attached Figure Description

[0026] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 The images show the appearance of the three composite coating solutions (primary composite, soluble composite, and coagulation composite) prepared in Comparative Example 1, Example 2, and Example 1, respectively.

[0028] Figure 2 SEM images of the three composite coating solutions (primary composite, soluble composite, and coagulation composite) prepared in Comparative Example 1, Example 2, and Example 1, respectively.

[0029] Figure 3 These are the contact angle results for the three composite coating solutions;

[0030] Figure 4 This is the result of the moisture content of the fried French fries;

[0031] Figure 5 This is the result of the oil content of the fried French fries;

[0032] Figure 6 These are the surface SEM results of fried French fries;

[0033] Figure 7 This is the apparent color result of fried French fries. Detailed Implementation

[0034] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0035] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this description, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0036] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Example 1

[0038] A method for preparing a composite coating solution that can reduce grease penetration includes the following steps:

[0039] Preparation of 2% (w / v) whey protein (WP) stock solution: Accurately weigh whey protein powder, dissolve it in deionized water, stir at room temperature for 3 hours, and then place it in a 4°C refrigerator for overnight hydration to obtain a protein solution concentration of 2% (20 mg / mL);

[0040] Preparation of 1% (w / v) sodium alginate (SA) stock solution: Accurately weigh a certain amount of sodium alginate powder, dissolve it in deionized water, stir at room temperature for more than 3 hours until completely dissolved, and then place it in a 4℃ refrigerator for overnight hydration to obtain a sodium alginate solution with a concentration of 1% (10mg / mL).

[0041] Preparation of WP-SA composite coating solution:

[0042] A WP-SA composite solution was prepared at a composite ratio of 5:1 (w / w). Under stirring, the pH of the mixed solution was adjusted to 3.5 with 0.5 mol / L HCl solution and 0.5 mol / L NaOH solution to obtain the composite coating solution.

[0043] Example 2

[0044] A method for preparing a composite coating solution that can reduce grease penetration includes the following steps:

[0045] Preparation of 2% (w / v) whey protein (WP) stock solution: Accurately weigh whey protein powder, dissolve it in deionized water, stir at room temperature for 3 hours, and then place it in a 4°C refrigerator for overnight hydration to obtain a protein solution concentration of 2% (20 mg / mL);

[0046] Preparation of 1% (w / v) sodium alginate (SA) stock solution: Accurately weigh a certain amount of sodium alginate powder, dissolve it in deionized water, stir at room temperature for more than 3 hours until completely dissolved, and then place it in a 4℃ refrigerator for overnight hydration to obtain a sodium alginate solution with a concentration of 1% (10mg / mL).

[0047] Preparation of WP-SA composite coating solution:

[0048] A WP-SA composite solution was prepared at a composite ratio of 5:1 (w / w). Under stirring, the pH of the mixed solution was adjusted to 4.5 with 0.5 mol / L HCl solution and 0.5 mol / L NaOH solution to obtain the composite coating solution.

[0049] Comparative Example 1

[0050] A method for preparing a composite coating solution that can reduce grease penetration includes the following steps:

[0051] Preparation of 2% (w / v) whey protein (WP) stock solution: Accurately weigh whey protein powder, dissolve it in deionized water, stir at room temperature for 3 hours, and then place it in a 4°C refrigerator for overnight hydration to obtain a protein solution concentration of 2% (20 mg / mL);

[0052] Preparation of 1% (w / v) sodium alginate (SA) stock solution: Accurately weigh a certain amount of sodium alginate powder, dissolve it in deionized water, stir at room temperature for more than 3 hours until completely dissolved, and then place it in a 4℃ refrigerator for overnight hydration to obtain a sodium alginate solution with a concentration of 1% (10mg / mL).

[0053] Preparation of WP-SA composite coating solution:

[0054] Prepare a WP-SA composite solution at a ratio of 5:1 (w / w) without adjusting the pH value, and stir to obtain a composite coating solution (with a pH value close to 7).

[0055] Figure 1 (Appearance diagram) From left to right are the composite coating solutions formed by Comparative Example 1, Example 2 and Example 1 (pH 7; 4.5; 3.5), which respectively form a primary complex, a soluble complex and a coagulated complex.

[0056] Figure 2 (SEM image) From left to right are the composite coating solutions formed by Comparative Example 1, Example 2 and Example 1 (pH 7; 4.5; 3.5), which respectively form primary complex, soluble complex and coagulated complex.

[0057] It can be seen that the primary complex particles are relatively small and scattered. At pH 4.5, the WP-SA complex remains suspended and turbid due to strong interactions, with some aggregation, and is a soluble complex. When the pH drops to 3.5, due to the continued enhancement of the interaction between proteoglycans, the particle size continues to increase, the aggregation between complexes intensifies, and aggregates are formed, which are aggregated complexes. The aggregates have a compact structure, which is more conducive to reducing water loss and oil penetration.

[0058] Characterization of the hydrophilicity and hydrophobicity of different complexes:

[0059] Figure 3 The contact angle results showed that WP+SA-PC (primary complex) exhibited a contact angle of approximately 44.73°, demonstrating high hydrophilicity; while WP+SA-SC (soluble complex) and WP+SA-COA (aggregate complex) had contact angles of approximately 74.49° and 102.32°, respectively. With decreasing pH, the net surface charge decreased, the electrostatic repulsion weakened, and the tendency for the complexes to attract each other increased, making them more conducive to accumulation at the oil-water interface, resulting in stronger hydrophobicity and more stable complex properties.

[0060] The effects of different composite coating solutions on the moisture and oil content of fried French fries:

[0061] A control group was set up without the addition of any composite coating solution. Figure 4 and 5The results showed that changes in moisture content during frying indicated the intensity of the frying process; the faster the moisture content decreased, the more intense the frying process. In the initial stage of frying (0-1 min), the moisture content rapidly evaporated and decreased sharply, while the oil content increased dramatically. Subsequently, the rate of moisture loss in the potato fries slowed down and eventually stabilized. At each frying time, compared to the uncoated group, all different composite coating solutions showed effects in reducing moisture loss and inhibiting oil absorption. The WP+SA-COA coagulant composite coating solution group showed the best effect, indicating that the cross-linked coagulant structure of the WP+SA-COA composite coagulant has excellent barrier properties. Its high hydrophobicity and stable structure act as a protective barrier, effectively reducing adverse changes during the frying process of the French fries.

[0062] The effects of different composite coating solutions on the surface microstructure of fried French fries:

[0063] Potato fries from the blank group and the three coated groups, after being dipped and fried for 5 minutes, were freeze-dried to remove oil. The surface microstructure was characterized, and the results are as follows: Figure 6 As shown, (a), (b), (c), and (d) represent the blank group, the WP+SA-PC group, the WP+SA-SC group, and the WP+SA-COA group, respectively. It can be seen that the blank group, lacking the protective effect of the coating, exhibits severe breakage and wrinkles on the surface of the potato fries, along with numerous pores. The degree of damage decreases sequentially from the WP+SA-PC group to the WP+SA-SC group and the WP+SA-COA group. The WP+SA-COA group has the smoothest surface with virtually no visible pores. This indicates that the WP+SA-COA cohesive complex structure provides excellent protection for the potato fries, reducing pores and roughness on the surface, thereby minimizing oil penetration.

[0064] The effect of different composite coating solutions on the surface color of fried French fries:

[0065] The loss of L* value makes the color and appearance of fried products darker. The WP+SA-SC group has the highest L* value, indicating the best brightness. The a* value shows the reddishness of fried products and is an indicator of browning (color change) during the frying process of potato chips. Uncoated chips have the highest a* value, indicating that they lack the protection of the coating during the frying process and therefore brown severely. Yellow (b*) is the most ideal color attribute for fried products, and the colorimetric results are as follows: Figure 7As shown, after 5 minutes of frying, the uncoated group of French fries had the lowest b-value, while the WP+SA-COA group had the highest and the most vibrant yellow color, indicating that the coating also enhances the aesthetic appeal. The color change intensity (ΔE) value was reported as a function of frying time and edible coating type. During frying, the ΔE values ​​of both the uncoated control and coated French fries increased. Under the same conditions, the highest and lowest ΔE values ​​were found in the uncoated group and the WP+SA-COA group, respectively. This indicates that the color change was greatest without the coating, resulting in the most severe color loss during frying. WP+SA-COA, with its excellent barrier properties, reduces undesirable browning during frying, thus preserving the color.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a composite coating solution that can reduce grease penetration, characterized in that, Includes the following steps: Step a1: Preparation of whey protein stock solution: Weigh whey protein powder and dissolve it in deionized water. Stir until completely dissolved at room temperature and then place in a refrigerator for hydration to obtain a whey protein solution with a concentration of 20 mg / ml. Step a2: Preparation of sodium alginate mother liquor: Weigh sodium alginate powder and dissolve it in deionized water. Stir until completely dissolved at room temperature and then place it in a refrigerator for hydration to obtain sodium alginate solution with a concentration of 10 mg / ml. Step a3: Mix the whey protein solution and sodium alginate solution obtained in steps a1 and a2, and adjust the pH of the mixed solution to 4.5-3.5 under stirring to obtain the composite coating solution.

2. The method for preparing the composite coating solution that reduces grease penetration according to claim 1, characterized in that, In step a3, NaOH solution and hydrochloric acid are used to adjust the pH value of the mixed solution, and the concentration of both NaOH solution and hydrochloric acid is 0.5 mol / L.

3. The method for preparing the composite coating solution that reduces grease penetration according to claim 1, characterized in that, In step a3, the pH of the mixed solution is adjusted to 3.

5.

4. The composite coating solution that reduces grease penetration is prepared by the preparation method according to any one of claims 1-3.

5. A method for frying French fries using the composite coating solution described in claim 4, characterized in that, Includes the following steps: Step b1: Wash the potatoes thoroughly and cut them into 1*1*5cm potato strips using a strip cutter. Blanch the potato strips at 95℃ for 4 minutes to inactivate enzymes, remove surface starch, and gelatinize the starch. Then cool them in running cold water for 1 minute to room temperature and wipe off excess moisture with paper towels. Step b2: Immerse the potato strips prepared in step b1 in the composite coating solution, then remove them and place them on the wire mesh to drain excess solution from the surface. Step b3: Fry the potato fries obtained in step b2 in a deep fryer containing soybean oil. After frying, place the fries on a wire mesh to cool for 10 minutes and drain off excess oil.

6. The method for frying French fries according to claim 5, characterized in that, In step b2, the ratio of the mass of the potato strips to the volume of the composite coating solution is 1:4; the soaking time is 5 minutes.

7. The method for frying French fries according to claim 5, characterized in that, The frying temperature in step b3 is 150°C.

8. The method for frying French fries according to claim 5, characterized in that, In step b3, the ratio of the volume of oil to the mass of the potato strips is 25:1.

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