A batter for microwaveable pre-fried food and its application

Abstract

The present invention discloses an outer coating paste for microwaveable pre-fried foods and its application, belonging to the technical field of fried food processing. The outer coating paste of the present invention comprises, by weight, 20-25 parts of strong dielectric starch, 20-25 parts of flour, 1-5 parts of soy protein isolate, 0.5-2.5 parts of xanthan gum, 0.5-1.5 parts of salt, 0.5-1.5 parts of spices, and 50-100 parts of water; the strong dielectric starch is obtained by cross-linking and modifying oxidized starch with calcium ions; the microwaveable pre-fried foods prepared using the outer coating paste have good crispness and color after microwave reheating, which solves the problem of loss of crispness faced by microwaveable fried foods, is conducive to promoting the industrial development of fried foods, a traditional food, and has broad application prospects in the field of fried food processing.

Description

Technical Field

[0001] The invention relates to a coating batter for microwaveable pre-fried food and application thereof, belonging to the technical field of fried food processing. Background Art

[0002] Deep-frying is a traditional food processing method. Fried foods are popular among consumers for their golden color, aromatic aroma, and crispy taste. However, the preparation of fried foods is cumbersome, and home-made cooking produces a lot of oil fume pollution, so consumers often do not like to fry and cook at home. The development of the microwave food and quick-frozen food industries has provided a possible solution to the problem of industrialization of traditional fried foods. Microwaveable frozen pre-fried foods refer to foods that are deep-fried and then frozen for storage, and then reheated using microwave equipment before consumption. They overcome the cumbersome and complex problems of home-made fried foods, help consumers process and eat fried foods more conveniently, and promote the industrialization of fried foods, a traditional food. However, there are differences between microwave heating and traditional heating, which makes it easy for foods to lose their good crispy and crunchy taste during microwave heating, and it is impossible to obtain good color quality. This is the most important problem restricting its development.

[0003] The principle of microwave heating is to cause the polar molecules inside the food (mainly water molecules) to become electrically polarized. The polarized water molecules vibrate and collide with the change in the direction of the microwave electric field, generating heat. Fried foods are characterized by being "crispy on the outside and tender on the inside". The outer skin has a low moisture content and poor microwave absorption and heat conversion capabilities. During microwave heating, the outer skin cannot be heated to the ideal temperature and cannot produce crispness (the outer skin has poor microwave heat conversion capabilities and the temperature does not rise enough).

[0004] In the prior art, methods for preventing microwave pre-fried foods from losing crispness are usually adopted, such as optimizing the outer coating formula, optimizing the frying pretreatment method, and using new frying technology. For example, researchers usually add modified starch, hydrophilic colloids, etc. to the fried outer coating to improve the crispness of fried foods and reduce moisture migration during microwave reheating to prevent crispness loss. For example, Chinese patent CN107242454B discloses a coating powder for frozen pre-fried foods, frozen pre-fried foods, and preparation methods thereof, which increase the crispness of fried foods by adding modified starch to the coating powder, wherein the modified starch is composed of high-amylose corn oxidized starch, distarch phosphate, and octenyl succinate starch. Chinese patent CN104223340A discloses a microwave pre-fried coating material and a method for processing cooked meat foods using the coating material, which achieves a crispy outer and tender inner taste by adding modified starch to the coating material; wherein the modified starch is prepared by distarch phosphate and hydroxypropyl starch in a mass ratio of 1:1. However, microwaveable frozen pre-fried foods made with existing batter coating formulas still have disadvantages such as poor sensory qualities such as crispness and color, which cannot meet consumer demand, thus limiting the further development of microwaveable pre-fried foods.

[0005] Therefore, there is an urgent need to develop a microwave-safe pre-fried food coating formula that can maintain crispness, which has important economic value and social significance for promoting the industrialization of traditional fried foods and the development of the entire food industry. Summary of the Invention

[0006] In view of the shortcomings and defects of the prior art, the purpose of the present invention is to solve the problem in the prior art that microwave pre-fried foods lose their crispness during microwave reheating and cannot obtain an ideal color.

[0007] A food's dielectric properties measure its ability to absorb microwave energy and convert it into heat. The stronger the food's dielectric properties, the more efficient it is at absorbing and converting microwave energy into heat. Microwaveable pre-fried foods are typically coated in batter before frying. Starch is the primary ingredient in this coating, and natural starch is typically a polymer with weak dielectric properties.

[0008] Based on this, the present invention proposes a coating paste for microwaveable pre-fried foods and its application. Specifically, starch with strong dielectric properties is prepared by oxidizing starch and then cross-linking it with calcium ions. The coating paste for microwaveable pre-fried foods is prepared using the starch with strong dielectric properties as the main raw material. The pre-fried foods prepared using the coating paste can maintain good crispness and color when reheated in a microwave.

[0009] A first object of the present invention is to provide a coating batter for microwaveable pre-fried foods. The coating batter comprises, by weight, 20 to 25 parts of starch with strong dielectric properties, 20 to 25 parts of flour, 1 to 5 parts of soy protein isolate, 0.5 to 2.5 parts of xanthan gum, 0.5 to 1.5 parts of salt, 0.5 to 1.5 parts of spices, and 50 to 100 parts of water. The starch with strong dielectric properties is obtained by cross-linking and modifying oxidized starch with calcium ions.

[0010] In one embodiment, the formula of the outer coating paste includes, by mass, 20 to 22 parts of starch with strong dielectric properties, 20 to 22 parts of flour, 1 to 3 parts of soy protein isolate, 0.5 to 1.5 parts of xanthan gum, 0.5 to 1 part of salt, 0.5 to 1 part of spices, and 50 to 100 parts of water; the starch with strong dielectric properties is obtained by cross-linking and modifying oxidized starch with calcium ions.

[0011] In one embodiment, the formula of the outer coating paste includes, by mass, 20 parts of strong dielectric starch, 20 parts of flour, 1 part of soy protein isolate, 1 part of xanthan gum, 1 part of salt, 1 part of spices, and 50 parts of water; the strong dielectric starch is obtained by cross-linking and modifying oxidized starch with calcium ions.

[0012] In one embodiment, the oxidized starch is one or more of oxidized corn starch, oxidized tapioca starch, and oxidized potato starch.

[0013] In one embodiment, the specific preparation of the starch with strong dielectric properties includes: dispersing oxidized starch in an aqueous solution, adding anhydrous calcium chloride, adjusting the pH to alkaline, and performing calcium ion cross-linking modification; and obtaining the starch with strong dielectric properties through alcohol precipitation, centrifugation, drying, crushing, and sieving.

[0014] In one embodiment, the pH is adjusted to an alkaline pH value of 8-10.

[0015] In one embodiment, the pH is adjusted to an alkaline pH of 9.

[0016] In one embodiment, the mass ratio of the oxidized starch to water is 0.05-0.15:1, and the mass ratio of starch to anhydrous calcium chloride is 1-3:1.

[0017] In one embodiment, the mass ratio of the oxidized starch to water is 0.1:1, and the mass ratio of starch to anhydrous calcium chloride is 2:1.

[0018] In one embodiment, the temperature of the calcium ion cross-linking modification is 40 to 60° C., and the time is 2 to 4 hours.

[0019] In one embodiment, the temperature of the calcium ion cross-linking modification is 50° C. and the time is 3 hours.

[0020] In one embodiment, the centrifugal speed is 3500-4000 rpm, and the time is 10-15 min.

[0021] In one embodiment, the drying temperature is 40-50° C., and the drying time is 12-36 hours.

[0022] In one embodiment, the mesh size of the sieve is 100 to 200 meshes.

[0023] The second object of the present invention is to provide a use of the above-mentioned batter in fried foods.

[0024] A third object of the present invention is a method for preparing a pre-fried outer batter for crisping microwave-frozen pre-fried foods, the method comprising the following steps:

[0025] (1) Weigh oxidized corn starch and mix with water, add anhydrous calcium chloride, stir evenly, and use sodium hydroxide to adjust the pH value to alkaline for calcium ion crosslinking;

[0026] (2) cooling the starch solution after cross-linking in step (1) at room temperature, then adding anhydrous ethanol, centrifuging, and drying; grinding and sieving the dried sample to obtain modified starch with strong dielectric properties;

[0027] (3) Dispersing 20-25 parts of the strong dielectric starch obtained in step (2), 20-25 parts of flour, 1-5 parts of soy protein isolate, 0.5-2.5 parts of xanthan gum, 0.5-1.5 parts of salt, and 0.5-1.5 parts of spices in 50-100 parts of deionized water, and uniformly dispersing and mixing to obtain a batter for microwave pre-fried food.

[0028] A fourth object of the present invention is to provide a method for improving the crispness of frozen fried foods after microwave reheating, the method comprising coating the fried foods with the above-described outer batter, frying, freezing, and microwave reheating.

[0029] In one embodiment, the frying condition is 150-180° C. and the frying time is 5-8 minutes.

[0030] In one embodiment, the microwave reheating power is 700-800W, and the heating time is 2-3 minutes.

[0031] A fifth object of the present invention is to provide a fried food that can be re-crisped in a microwave, which is obtained by coating the fried food with the above-mentioned outer batter, frying it, and freezing it.

[0032] In one embodiment, the frying condition is 150-180° C. and the frying time is 5-8 minutes.

[0033] Beneficial effects of the present invention:

[0034] The present invention is based on the synergistic effect of starch oxidation modification and calcium ion cross-linking, which promotes the oxidation of starch hydroxyl groups into carboxyl groups to form cross-linked complexes with calcium ions under alkaline conditions. The ion polarization effect generated by calcium ions improves the dielectric properties of starch, thereby improving its microwave absorption and heating efficiency during microwave heating. The fried outer coating paste prepared using starch with strong dielectric properties as raw material exhibits stronger dielectric properties and has better microwave heating efficiency during microwave reheating, thereby reducing the generation of temperature gradients inside and outside the food during the microwave process and preventing the moisture in the food core from migrating to the outer shell along the temperature gradient. The outer coating paste also has good water resistance and can effectively prevent the migration of moisture inside the food to the outer shell. It can form excellent crispness and color quality after microwave reheating, which helps to improve the sensory quality of microwave pre-fried foods and promote the development of the microwave pre-fried food industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1This is a flow chart for preparing starch with strong dielectric properties in the present invention. DETAILED DESCRIPTION

[0036] The present invention will be further described below with reference to examples, but the embodiments of the present invention are not limited thereto.

[0037] The oxidized corn starch involved in the present invention was purchased from Hangzhou Prostar Starch Co., Ltd. with the product number M0340 and a viscosity of ≤1500BU (dry basis 25%); calcium chloride was purchased from Shanghai Titan Technology Co., Ltd.; xanthan gum was purchased from Beijing Wokai Biotechnology Co., Ltd.; and glycerol was purchased from Beijing Yinuokai Technology Co., Ltd.

[0038] The measuring method of the present invention

[0039] 1. Dielectric properties test

[0040] The dielectric properties of starch were measured using an Agilent E8362B vector network analyzer and a rectangular waveguide resonator. The resonator used a WR430 waveguide, operating in TE105 mode at a frequency of 2450 MHz. After maintaining the temperature in a constant-temperature chamber, each sample was placed in the resonator, starting with an empty glass tube (3 mm inner diameter) and then the tubes containing each sample. The vector network analyzer swept the frequency from 2.25 GHz to 2.55 GHz, recording the resonant frequency and transmission coefficient (S21) of the resonator for each case. Three replicates were taken for each sample, and the results were averaged. Substituting these results into Equation 1, the real and imaginary parts of the dielectric constant can be calculated.

[0041] The starch samples obtained during the preparation of each embodiment and comparative example were respectively taken for testing.

[0042] 2. Brittleness test

[0043] Taking fried chicken nuggets as an example, the pre-treated chicken breast nuggets to be fried are soaked in the outer batter obtained in the embodiment and the comparative example for 30 seconds and fried at 180°C for 5 minutes. The fried food is placed in a -18°C refrigerator and frozen for 48 hours. The frozen fried food is heated at a microwave power of 700W for 2 minutes. Microwave-safe frozen pre-fried foods of the same size are selected and measured using the TA-XTPlus texture analyzer (P / 2 probe). The measurement conditions are as follows: pre-measurement rate 0.5mm / s; test rate 0.5mm / s; post-measurement rate 5mm / s. The measurement adopts compression mode, the compression distance is 80%, the contact force is 5g, and 10 parallel measurements are performed.

[0044] 3. Determination of color difference

[0045] The frying and microwave heating processes are the same as above; a camera is used to record the color changes of the sample comparison and embodiment samples after pre-frying and microwave, and the WSC-S type fully automatic colorimeter is used for measurement. The working conditions are: C / 2 light source, colorimetric spot diameter of 10mm, and a standard ceramic white plate as the standard sample. The International Illumination Association CIE L*a*b* uniform color space colorimetric system is applied, and the L* value (lightness) varies from 0 to 100, 0 represents black, and 100 represents white. The a* value (Redness) represents the value from red to green, 100 is red, and -80 is green. The b* value (Yellowness) represents the value from yellow to blue; 100 is yellow, and -80 is blue. Each sample is read from different angles, measured three times, and the average of the three readings is taken. The total color difference (TCD) is calculated using the equation:

[0046]

[0047] 4. Determination of water vapor transmission rate of batter layer

[0048] 2g of the strong dielectric starch obtained in Examples 1-5, the corn starch and oxidized corn starch in Comparative Examples 1 and 2, and the strong dielectric starch obtained in Comparative Examples 3-5, 1g of flour, 1g of xanthan gum, and 1g of glycerin were dispersed in 100mL of deionized water. The mixture was stirred and gelatinized in a 90°C waterbath for 1 hour, and then cooled to 50°C to obtain a batter coating film. 30g of the coating film solution was cast onto a polytetrafluoroethylene plate and dried in a 50°C oven for 8 hours. The film was then peeled off and allowed to equilibrate at 50% humidity for 24 hours to produce a batter coating film.

[0049] After humidity equilibration, the coated film was cut into a circular shape with a radius of 13-15 mm and tightly sealed into the mouth of a 50 mL centrifuge tube. 3 g of anhydrous CaCl2 was pre-loaded into the tube. After sealing, the tube was weighed and placed in a 100% humidity environment. The weight change was recorded every 24 hours. The water permeability (WVP) of the label was calculated using the equation:

[0050]

[0051] Where: Δm (g) is the weight increase of the centrifuge tube; h (m) is the thickness of the thin label; A (m 2 ) is the area corresponding to the inner diameter of the centrifuge tube; ΔP (2339 Pa, 20°C) is the water vapor pressure; t (s) is the time.

[0052] Example 1

[0053] A method for preparing a pre-fried outer batter for crisping microwave-frozen pre-fried food comprises the following steps:

[0054] (1) Weigh 30 g of oxidized corn starch and mix it with 300 mL of water, add 15 g of anhydrous calcium chloride, stir evenly, adjust the pH value to 9 with sodium hydroxide, and heat it to 50°C in a constant temperature water bath for 3 h to perform calcium ion crosslinking;

[0055] (2) The cross-linked starch solution in step (1) was cooled at room temperature (25° C.), and then three times the volume of anhydrous ethanol was added, and the mixture was centrifuged at 4000 rpm for 10 minutes, and then dried in an oven at 50° C. for 24 hours; the dried sample was ground and sieved with a 100-mesh sieve to obtain a modified starch with strong dielectric properties;

[0056] (3) Disperse 20 g of the strong dielectric starch obtained in step (2), 20 g of flour, 1 g of xanthan gum, 0.5 g of soy protein isolate, 1 g of salt, and 1 g of spices in 50 mL of deionized water, and mix them evenly to obtain a batter for microwaveable pre-fried food.

[0057] Example 2

[0058] A method for preparing a pre-fried outer batter for crisping microwave-frozen pre-fried food comprises the following steps:

[0059] (1) Weigh 30 g of oxidized cassava starch and mix it with 300 mL of water, add 15 g of anhydrous calcium chloride, stir evenly, adjust the pH value to 9 with sodium hydroxide, and heat it to 50° C. in a constant temperature water bath for 3 h to perform calcium ion crosslinking;

[0060] (2) The cross-linked starch solution in step (1) was cooled at room temperature (25° C.), and then three times the volume of anhydrous ethanol was added, and the mixture was centrifuged at 4000 rpm for 10 minutes, and then dried in an oven at 50° C. for 24 hours; the dried sample was ground and sieved with a 100-mesh sieve to obtain a modified starch with strong dielectric properties;

[0061] (3) Disperse 20 g of the strong dielectric starch obtained in step (2), 20 g of flour, 1 g of xanthan gum, 0.5 g of soy protein isolate, 1 g of salt, and 1 g of spices in 50 mL of deionized water, and mix them evenly to obtain a batter for microwaveable pre-fried food.

[0062] Example 3

[0063] A method for preparing a pre-fried outer batter for crisping microwave-frozen pre-fried food comprises the following steps:

[0064] (1) Weigh 30 g of oxidized potato starch and mix it with 300 mL of water, add 15 g of anhydrous calcium chloride, stir evenly, adjust the pH value to 9 with sodium hydroxide, and heat it to 50°C in a constant temperature water bath for 3 h to perform calcium ion crosslinking;

[0065] (2) The cross-linked starch solution in step (1) was cooled at room temperature (25° C.), and then three times the volume of anhydrous ethanol was added, and the mixture was centrifuged at 4000 rpm for 10 minutes, and then dried in an oven at 50° C. for 24 hours; the dried sample was ground and sieved with a 100-mesh sieve to obtain a modified starch with strong dielectric properties;

[0066] (3) Disperse 20 g of the strong dielectric starch obtained in step (2), 20 g of flour, 1 g of xanthan gum, 0.5 g of soy protein isolate, 1 g of salt, and 1 g of spices in 50 mL of deionized water, and mix them evenly to obtain a batter for microwaveable pre-fried food.

[0067] Example 4

[0068] A method for preparing a pre-fried outer batter for crisping microwave-frozen pre-fried food comprises the following steps:

[0069] (1) Weigh 30 g of oxidized corn starch and mix it with 300 mL of water, add 15 g of anhydrous calcium chloride, stir evenly, adjust the pH value to 9 with sodium hydroxide, and heat it to 50°C in a constant temperature water bath for 2 h to perform calcium ion crosslinking;

[0070] (2) The cross-linked starch solution in step (1) was cooled at room temperature (25° C.), and then three times the volume of anhydrous ethanol was added, and the mixture was centrifuged at 4000 rpm for 10 minutes, and then dried in an oven at 50° C. for 24 hours; the dried sample was ground and sieved with a 100-mesh sieve to obtain a modified starch with strong dielectric properties;

[0071] (3) Disperse 25 g of the strong dielectric starch obtained in step (2), 25 g of flour, 2 g of xanthan gum, 4 g of soy protein isolate, 1.5 g of salt, and 1.5 g of spices in 100 mL of deionized water, and mix them evenly to obtain a batter for microwaveable pre-fried food.

[0072] Example 5

[0073] A method for preparing a pre-fried outer batter for crisping microwave-frozen pre-fried food comprises the following steps:

[0074] (1) Weigh 30 g of oxidized corn starch and mix it with 300 mL of water, add 15 g of anhydrous calcium chloride, stir evenly, adjust the pH value to 10 with sodium hydroxide, and heat it to 60°C in a constant temperature water bath for 4 h to perform calcium ion crosslinking;

[0075] (2) The starch solution after cross-linking in step (1) was placed at room temperature (25° C.) and cooled, and then three times the volume of anhydrous ethanol was added, and the mixture was centrifuged at 3500 rpm for 15 minutes, and then dried in a 50° C. oven for 24 hours; the dried sample was ground and sieved with a 100-mesh sieve to obtain a modified starch with strong dielectric properties;

[0076] (3) Disperse 20 g of the strong dielectric starch obtained in step (2), 20 g of flour, 1 g of xanthan gum, 0.5 g of soy protein isolate, 1 g of salt, and 1 g of spices in 50 mL of deionized water, and mix them evenly to obtain a batter for microwaveable pre-fried food.

[0077] Comparative Example 1

[0078] Disperse 20 g of flour, 20 g of corn starch, 1 g of xanthan gum, 0.5 g of soy protein isolate, 1 g of salt, and 1 g of spices in 50 mL of deionized water, and mix them evenly to obtain the outer coating paste.

[0079] Comparative Example 2

[0080] Disperse 20 g of flour, 20 g of oxidized corn starch, 1 g of xanthan gum, 0.5 g of soy protein isolate, 1 g of salt, and 1 g of spices in 50 mL of deionized water, and mix them evenly to obtain a coating paste.

[0081] Comparative Example 3

[0082] (1) Weigh 30 g of corn starch and mix with 300 mL of water, stir evenly, adjust the pH to 9 with sodium hydroxide, and heat to 50°C in a constant temperature water bath for 3 h to form a starch emulsion;

[0083] (2) The starch emulsion obtained in step (1) was placed at room temperature (25° C.) and cooled, and then three times the volume of anhydrous ethanol was added, centrifuged at 4000 rpm, and then dried in a 50° C. oven for 24 h; the dried sample was ground and sieved with a 100-mesh sieve to obtain modified starch;

[0084] (3) Disperse 20 g of the modified starch obtained in step (2), 20 g of flour, 1 g of xanthan gum, 0.5 g of soy protein isolate, 1 g of salt, and 1 g of spices in 50 mL of deionized water, and mix them evenly to obtain a coating paste.

[0085] Comparative Example 4

[0086] (1) Weigh 30 g of oxidized corn starch and mix with 300 mL of water, stir evenly, adjust the pH to 9 with sodium hydroxide, and heat to 50° C. in a constant temperature water bath for 3 h to form an oxidized corn starch emulsion;

[0087] (2) The oxidized corn starch emulsion obtained in step (1) was placed at room temperature (25° C.) and cooled, and then three times the volume of anhydrous ethanol was added, centrifuged at 4000 rpm, and then dried in a 50° C. oven for 24 h; the dried sample was ground and sieved with a 100-mesh sieve to obtain modified starch;

[0088] (3) Disperse 20 g of the modified starch obtained in step (2), 20 g of flour, 1 g of xanthan gum, 0.5 g of soy protein isolate, 1 g of salt, and 1 g of spices in 50 mL of deionized water, and mix them evenly to obtain a coating paste.

[0089] Comparative Example 5

[0090] (1) Weigh 30 g corn starch and mix it with 300 mL water, add 15 g anhydrous calcium chloride, stir evenly, adjust the pH value to 9 with sodium hydroxide, and heat it to 50 ° C in a constant temperature water bath for 3 h to perform calcium ion crosslinking;

[0091] (2) The starch solution after cross-linking in step (1) was placed at room temperature (25° C.) and cooled, and then three times the volume of anhydrous ethanol was added, centrifuged at 4000 rpm, and then dried in a 50° C. oven for 24 h; the dried sample was ground and sieved with a 100-mesh sieve to obtain modified starch;

[0092] (3) Disperse 20 g of the modified starch obtained in step (2), 20 g of flour, 1 g of xanthan gum, 0.5 g of soy protein isolate, 1 g of salt, and 1 g of spices in 50 mL of deionized water, and mix them evenly to obtain a coating paste.

[0093] Result determination

[0094] 1. The dielectric properties of the modified starch with strong dielectric properties obtained in Examples 1 to 5, the corn starch and oxidized corn starch in Comparative Examples 1 and 2, and the modified starch obtained in Comparative Examples 3 to 5 were measured. The results are shown in Table 1:

[0095] Table 1. Dielectric properties of starch

[0096]

[0097] As can be seen from Table 1, compared with Comparative Examples 1 to 5, the modified starches prepared in Examples 1 to 5 have higher dielectric constants and dielectric loss constants, indicating that calcium ion crosslinking modification effectively improves the dielectric properties of starch; among them, the starch in Example 1 exhibits higher dielectric constants and dielectric loss constants, indicating that the use of oxidized corn starch and calcium ion crosslinking can better improve the dielectric properties of starch.

[0098] 2. The pre-treated chicken breast pieces to be fried were immersed in the outer coating batter obtained in Examples 1 to 5 and Comparative Examples 1 to 5, and then fried, frozen, and microwaved to measure their brittleness. The results are shown in Table 2:

[0099] Frangibility refers to the distance between the probe contacting the food and the food breaking. The smaller the Frangibility value, the higher the brittleness of the food.

[0100] Table 2. Results of brittleness test on microwaveable frozen pre-fried foods

[0101]

[0102]

[0103] As shown in Table 2, the crispness of the microwaveable pre-fried foods prepared in Examples 1 to 5 was significantly improved compared to Comparative Examples 1 to 5. Specifically, the crispness of the microwaveable frozen pre-fried foods prepared using the coating batter in Example 1 was increased by 53.7% compared to Comparative Example 2, indicating that the coating batter prepared using the strong dielectric starch in Comparative Example 1 was effective in improving the crispness of microwaveable frozen pre-fried foods.

[0104] 3. The pre-treated chicken breast pieces to be fried were immersed in the outer coating batter obtained in Examples 1 to 5 and Comparative Examples 1 to 5, fried, frozen, and microwave-heated, and their color was measured. The results are shown in Table 3:

[0105] Table 3. Color measurement results of fried chicken nuggets

[0106]

[0107] As shown in Table 3, compared with Comparative Examples 1 to 5, the microwaveable frozen pre-fried chicken nuggets prepared using the strong dielectric starches in Examples 1 to 5 as batter raw materials have higher L* and b* values, showing higher brightness and golden color. Among them, the frozen pre-fried chicken nuggets prepared using the strong dielectric starch in Example 1 as a raw material exhibited the highest L* and b* values, indicating that the outer coating batter prepared using the strong dielectric starch can better improve the color quality of the frozen pre-fried chicken nuggets.

[0108] 4. 30g of the batter film liquid prepared in Examples 1-5 and Comparative Examples 1-5 was weighed and cast onto a polytetrafluoroethylene flat plate. The plate was then dried in a 50°C oven for 8 hours. The plate was peeled off and allowed to equilibrate at 50% humidity for 24 hours to produce a batter coating film. The water permeability of the coating film was measured, and the results are shown in Table 4:

[0109] Table 4. Coating water vapor transmission rate test results

[0110]

[0111]

[0112] As shown in Table 1, the coatings prepared in Examples 1-5 exhibit lower water vapor transmission rates compared to Comparative Examples 1-5, indicating that calcium ions can cross-link with starch, reducing the hydrophilicity of the starch in the coating film, thereby improving the coating film's water barrier properties. Among them, Example 1 exhibits the lowest water transmission rate, indicating that the batter coating film prepared with strong dielectric starch and flour has better water barrier properties.

[0113] The embodiments provided above are not intended to limit the scope of the present invention, nor are the steps described to limit their execution order. Any obvious improvements to the present invention made by those skilled in the art in combination with existing common knowledge shall fall within the scope of protection defined by the claims of the present invention.

Claims

1. A batter for microwaveable pre-fried food, characterized in that: The outer coating paste comprises, by weight, 20-25 parts of starch with strong dielectric properties, 20-25 parts of flour, 1-5 parts of soy protein isolate, 0.5-2.5 parts of xanthan gum, 0.5-1.5 parts of salt, 0.5-1.5 parts of spices, and 50-100 parts of water. The starch with strong dielectric properties is obtained by cross-linking and modifying oxidized starch with calcium ions. The starch with strong dielectric properties is prepared by dispersing the oxidized starch in an aqueous solution, adding anhydrous calcium chloride, adjusting the pH to 8-10, and performing calcium ion cross-linking modification; and then performing alcohol precipitation, centrifugation, drying, pulverizing, and sieving to obtain the starch with strong dielectric properties.

2. The outer coating paste according to claim 1, wherein The outer coating paste comprises, by weight, 20 to 22 parts of starch with strong dielectric properties, 20 to 22 parts of flour, 1 to 3 parts of soy protein isolate, 0.5 to 1.5 parts of xanthan gum, 0.5 to 1 part of salt, 0.5 to 1 part of spices, and 50 to 100 parts of water. The starch with strong dielectric properties is obtained by cross-linking and modifying oxidized starch with calcium ions.

3. The outer coating paste according to claim 1, characterized in that The formula of the outer coating paste includes, by mass, 20 parts of strong dielectric starch, 20 parts of flour, 1 part of soy protein isolate, 1 part of xanthan gum, 1 part of salt, 1 part of spices, and 50 parts of water; the strong dielectric starch is obtained by cross-linking and modifying oxidized starch with calcium ions.

4. The outer coating paste according to any one of claims 1 to 3, characterized in that The oxidized starch is one or more of oxidized corn starch, oxidized tapioca starch, and oxidized potato starch.

5. The outer coating paste according to claim 1, wherein In the preparation of the starch with strong dielectric properties, the mass ratio of oxidized starch to water is 0.05 to 0.15:1, and the mass ratio of oxidized starch to anhydrous calcium chloride is 1 to 3:

1.

6. The outer coating paste according to claim 1, characterized in that In the preparation of the starch with strong dielectric properties, the mass ratio of oxidized starch to water is 0.1:1, and the mass ratio of oxidized starch to anhydrous calcium chloride is 2:

1.

7. The outer coating paste according to claim 1, characterized in that The adjusted pH value is 9.

8. The outer coating batter according to claim 1, wherein The temperature of the calcium ion cross-linking modification is 40 to 60° C., and the time is 2 to 4 hours.

9. The outer coating batter according to claim 1, wherein The centrifugal speed is 3500-4000 rpm and the time is 10-15 min.

10. The outer coating batter according to claim 1, wherein The drying temperature is 40-50°C and the drying time is 12-36 hours.

11. The outer coating batter according to claim 1, wherein The mesh size of the sieve is 100 to 200 meshes.

12. Use of the outer coating paste according to any one of claims 1 to 11 in food preparation.

13. A method for preparing a batter for microwaveable pre-fried food according to any one of claims 1 to 11, characterized in that: The method comprises the following steps: (1) Weigh oxidized starch and mix with water, add anhydrous calcium chloride, stir evenly, adjust the pH value to alkaline with sodium hydroxide, and perform calcium ion crosslinking; (2) The cross-linked starch solution in step (1) is cooled at room temperature, and then anhydrous ethanol is added, centrifuged, and dried; the dried sample is ground and sieved to obtain a modified starch with strong dielectric properties; (3) The strong dielectric starch obtained in step (2), flour, soy protein isolate, xanthan gum, salt, and spices are dispersed in deionized water and uniformly mixed to obtain a batter for microwave pre-fried food.

14. A method for improving the crispness of frozen fried food after microwave reheating, characterized in that: The method comprises coating the fried food with the outer coating batter according to any one of claims 1 to 11, frying, freezing, and reheating in a microwave.

15. The method according to claim 14, characterized in that The frying condition is 150-180° C. and the frying time is 5-8 minutes.

16. The method according to claim 14, wherein The microwave reheating power is 700-800 W, and the heating time is 2-3 min.

17. A fried food that can be re-crisped in a microwave, characterized in that: The food is obtained by coating fried food with the outer coating batter according to any one of claims 1 to 11, frying, and freezing.

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