A brittle coating for microwaveable frozen pre-fried food and its preparation method and application

Abstract

The present invention discloses a brittle coating for microwaveable frozen pre-fried foods, and its preparation method and application, belonging to the technical field of fried foods. The raw materials of the brittle coating of the present invention, measured in parts by mass, include: 3 to 6 parts of brittle starch, 1 to 3 parts of hydrophilic colloid, 1 to 3 parts of glycerol, and 100 to 300 parts of water; the brittle starch is obtained by cross-linking and modifying oxidized starch with calcium ions. The brittle coating has a good water-blocking effect and can effectively solve the problem of loss of brittleness of microwaveable frozen pre-fried foods during microwave reheating; when microwaveable frozen pre-fried foods prepared using the brittle coating are microwave reheated, the brittleness is improved by 47.3% compared with ordinary corn starch, and the color quality is also good.

Description

Technical Field

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

[0002] Frying is a traditional processing method. Fried foods are loved by consumers because of their golden color, aromatic smell and crispy taste. However, fried foods are complicated to make and home-made ones cause a lot of oil fume pollution, so consumers often do not like to fry them at home.

[0003] The development of the microwave and quick-frozen food industries offers a potential solution to the challenges of industrializing traditional fried foods. Microwaveable frozen pre-fried foods overcome the complexities of home-made fried foods. However, differences in microwave heating, such as the loss of the food's crispy, fluffy texture, are a significant constraint to their development.

[0004] Microwave heating works by polarizing the polar molecules (primarily water molecules) within food. These polarized water molecules vibrate and collide with the changing direction of the microwave electric field, generating heat. Fried foods are known for being crispy on the outside and tender on the inside. The outer crust, however, has a low moisture content, so microwave heating prevents the outer crust from reaching the ideal temperature and creating crispness. Furthermore, the difference in moisture content between the inner and outer crust creates a temperature difference between the hot interior and the cool exterior, accelerating moisture migration to the outer crust. The cold air inside the microwave further limits moisture evaporation from the outer crust. This internal moisture migration causes the outer crust's moisture content to rise, resulting in a loss of crispness.

[0005] Existing solutions to the loss of crispness in microwaveable pre-fried foods typically involve optimizing batter formulations, optimizing pre-frying methods, using novel frying technologies, draining the oil after frying, and using microwave-sensitive packaging. However, these solutions remain ineffective in addressing the loss of crispness in microwaveable frozen pre-fried foods after microwave reheating, failing to meet consumer demand and limiting the further development of microwaveable pre-fried foods.

[0006] Therefore, there is an urgent need to develop a new method for increasing the crispness of microwave-safe frozen pre-fried foods, 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

[0007] In view of the shortcomings and defects of the existing technology, the purpose of the present invention is to solve the problem of loss of crispness of existing microwaveable frozen pre-fried foods after microwave reheating by using a microwaveable frozen pre-fried food brittle coating.

[0008] To this end, the present invention provides a brittle coating for microwaveable frozen pre-fried foods, and a preparation method and application thereof. The brittle coating is prepared by adopting oxidized starch and calcium ion cross-linking technology to prepare brittle modified starch, and the brittle modified starch is compounded with xanthan gum and glycerol to prepare a brittle coating for microwaveable frozen pre-fried foods. After the coating is soaked in the fried food, it can effectively prevent the diffusion of moisture inside the food into the crispy batter shell during microwave heating, thereby solving the problem of loss of brittleness of the microwaveable frozen pre-fried foods. Moreover, the brittleness of the microwaveable frozen pre-fried foods using the brittle coating can be increased by 50% compared with ordinary starch, and the foods have better color quality.

[0009] The first object of the present invention is to provide a brittle coating for microwaveable frozen pre-fried foods, wherein the raw materials of the brittle coating include, by mass, 3 to 6 parts of brittle starch, 1 to 3 parts of a hydrophilic colloid, 1 to 3 parts of glycerol, and 100 to 300 parts of water; the brittle starch is obtained by cross-linking and modifying oxidized starch with calcium ions.

[0010] In one embodiment, the raw materials of the brittle coating include, by mass, 3 to 5 parts of brittle starch, 1 to 2 parts of hydrophilic colloid, 1 to 2 parts of glycerol, and 100 to 200 parts of water; the brittle starch is obtained by cross-linking and modifying oxidized starch with calcium ions.

[0011] In one embodiment, the raw materials of the brittle coating include, by mass, 3 parts of brittle starch, 1 part of hydrophilic colloid, 1 part of glycerol, and 100 parts of water; the brittle starch is obtained by cross-linking and modifying oxidized starch with calcium ions.

[0012] In one embodiment, the brittle starch is prepared by 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 brittle starch by alcohol precipitation, centrifugation, drying, crushing, and sieving.

[0013] In one embodiment, the oxidized starch is one or more of oxidized corn starch, oxidized tapioca starch, and oxidized potato starch.

[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] In one embodiment, the hydrocolloid comprises one or more of xanthan gum, carrageenan, guar gum and pectin.

[0024] In one embodiment, the raw materials of the brittle coating include, by mass, 3 parts of brittle starch, 1 part of hydrophilic colloid, 1 part of glycerol, and 100 parts of water.

[0025] A second object of the present invention is to provide a method for preparing a brittle coating for microwaveable frozen pre-fried foods, the method comprising: dispersing brittle starch in deionized water, adding a hydrophilic colloid and glycerol, stirring evenly, heating and gelatinizing, and then stirring and cooling to obtain a brittle coating film liquid.

[0026] In one embodiment, the gelatinization temperature is 80-100°C.

[0027] In one embodiment, the gelatinization time is 30 to 60 minutes.

[0028] In one embodiment, the cooling temperature is 50-70°C.

[0029] The third object of the present invention is to provide an application of the above-mentioned embrittlement coating in the fields of food, medicine and chemical materials.

[0030] In one embodiment, the food product comprises a microwavable frozen pre-fried food product.

[0031] The fourth object of the present invention is to provide a method for preparing microwave-freezable pre-fried chicken nuggets, wherein the pre-treated chicken nuggets are immersed in the above-prepared brittle coating film liquid, taken out, drained, coated with batter, and fried; and after frying, the chicken nuggets are placed in a refrigerator for refrigeration.

[0032] In one embodiment, the formula of the flour paste in the batter includes: 20-25 parts of corn 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.

[0033] In one embodiment, the formula of the flour paste in the batter includes: 20 parts of corn starch, 20 parts of flour, 5 parts of soy protein isolate, 2 parts of xanthan gum, 1 part of salt, 1 part of spices, and 100 parts of water.

[0034] In one embodiment, the frying condition is 150-180° C. and the frying time is 5-8 minutes.

[0035] A fifth object of the present invention is to provide a fried chicken nugget that can be re-crisped in a microwave, wherein the chicken nugget is obtained by the above-mentioned preparation method.

[0036] The sixth object of the present invention is to provide a method for improving the crispness of frozen fried foods after microwave reheating, the method comprising soaking the fried foods in the above-prepared crispening coating film liquid, air-drying, and then coating, frying, freezing, and microwave reheating.

[0037] In one embodiment, the soaking time is 30 to 60 seconds.

[0038] In one embodiment, the frying condition is 150-180° C. and the frying time is 5-8 minutes.

[0039] In one embodiment, the microwave reheating power is 700-800W, and the heating time is 2-3 minutes.

[0040] In one embodiment, the freezing condition is -10°C to -20°C.

[0041] Beneficial effects of the present invention:

[0042] The present invention provides a brittle coating for microwaveable frozen pre-fried foods, and a preparation method and application thereof. The brittle coating prepared with brittle starch as a raw material has strong water barrier performance, which is improved by about 25% compared with ordinary corn starch film. The cross-linked calcium in the brittle starch improves its dielectric properties, and the microwave absorption and heat conversion performance of the coating are improved, which can effectively reduce the generation of temperature gradients between the inner core and the outer shell of the food during the microwave process, thereby effectively solving the problem of loss of brittleness of microwaveable frozen pre-fried foods during microwave reheating. In addition, the brittle coating can effectively prevent the internal moisture of the fried food from migrating to the outer batter layer during the microwave reheating process, so that the brittleness of the fried food is improved by about 50% compared with ordinary corn starch, and the fried food has better color quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a process flow chart of the embrittled coating prepared in Example 1 of the present invention; DETAILED DESCRIPTION

[0044] The present invention will be further described below with reference to the examples, but they are not intended to limit the present invention.

[0045] 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.

[0046] The present invention relates to a determination method:

[0047] 1. Determination of moisture permeability of embrittled coating

[0048] 30 g of the embrittled coating film liquid was poured onto a polytetrafluoroethylene plate by a casting method and placed in a 50° C. oven for 8 h to dry; the plate was peeled off and subjected to humidity equilibrium at 50% humidity for 24 h to obtain a 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] 2. Determination of the brittleness of microwaveable frozen pre-fried foods

[0053] Taking fried chicken nuggets as an example, pre-treated chicken breast nuggets were immersed in a crispening coating solution for 30 seconds, removed, drained, coated, and fried at 180°C for 5 minutes. The fried food was then frozen in a -18°C refrigerator for 48 hours. The frozen fried food was then heated in a microwave at 700W for 2 minutes. Microwaveable frozen pre-fried foods of uniform size were selected and measured using a TA-XTPlus texture analyzer (P / 2 probe). The measurement conditions were as follows: pre-measurement speed 0.5 mm / s; test speed 0.5 mm / s; post-measurement speed 5 mm / s. The measurement was performed in compression mode, with a compression distance of 80% and a contact force of 5 g. Ten replicates were used.

[0054] 3. Color determination of microwaveable frozen pre-fried foods

[0055] 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 standard ceramic white plate as 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:

[0056]

[0057] Example 1

[0058] A method for preparing a brittle coating for microwave frozen pre-fried food comprises the following steps:

[0059] (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;

[0060] (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 4000 rpm for 10 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 brittle starch;

[0061] (3) Disperse 3 g of the brittle starch obtained in step (2), 1 g of xanthan gum, and 1 g of glycerol in 100 mL of deionized water, stir and gelatinize in a 90° C. water bath for 1 h, and cool to 50° C. to obtain a brittle coating film liquid.

[0062] Example 2

[0063] A method for preparing a brittle coating for microwave frozen pre-fried food comprises the following steps:

[0064] (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;

[0065] (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 4000 rpm for 10 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 brittle starch;

[0066] (3) Disperse 3 g of the brittle starch obtained in step (2), 1 g of xanthan gum, and 1 g of glycerol in 100 mL of deionized water, stir and gelatinize in a 90° C. water bath for 1 h, and cool to 50° C. to obtain a brittle coating film liquid.

[0067] Example 3

[0068] A method for preparing a brittle coating for microwave frozen pre-fried food comprises the following steps:

[0069] (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;

[0070] (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 4000 rpm for 10 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 brittle starch;

[0071] (3) Disperse 3 g of the brittle starch obtained in step (2), 1 g of xanthan gum, and 1 g of glycerol in 100 mL of deionized water, stir and gelatinize in a 90° C. water bath for 1 h, and cool to 50° C. to obtain a brittle coating film liquid.

[0072] Example 4

[0073] A method for preparing a brittle coating for 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 9 with sodium hydroxide, and heat it to 50°C in a constant temperature water bath for 2 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 4000 rpm for 10 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 brittle starch;

[0076] (3) Disperse 5 g of the brittle starch obtained in step (2), 2 g of xanthan gum, and 2 g of glycerol in 100 mL of deionized water, stir and gelatinize in a 90° C. water bath for 1 h, and cool to 50° C. to obtain a brittle coating film liquid.

[0077] Example 5

[0078] A method for preparing a brittle coating for microwave frozen pre-fried food comprises the following steps:

[0079] (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 40°C in a constant temperature water bath for 4 h to perform calcium ion crosslinking;

[0080] (2) The starch solution cross-linked 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 3500 rpm for 15 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 brittle starch;

[0081] (3) Disperse 4 g of the brittle starch obtained in step (2), 3 g of xanthan gum, and 3 g of glycerol in 100 mL of deionized water, stir and gelatinize in a 90° C. water bath for 1 h, and cool to 50° C. to obtain a brittle coating film liquid.

[0082] Comparative Example 1

[0083] 3 g corn starch, 1 g xanthan gum, and 1 g glycerol were dispersed in 100 mL deionized water, stirred and gelatinized in a 90° C. water bath for 1 h, and cooled to 50° C. to obtain the embrittled coating film liquid.

[0084] Comparative Example 2

[0085] 3 g of oxidized corn starch, 1 g of xanthan gum, and 1 g of glycerol were dispersed in 100 mL of deionized water, stirred and gelatinized in a 90°C water bath for 1 h, and cooled to 50°C to obtain the embrittled coating film liquid.

[0086] Comparative Example 3

[0087] (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 corn starch solution;

[0088] (2) The corn starch solution of step (1) was cooled at room temperature (25° C.), and then three times the volume of anhydrous ethanol was added, centrifuged at 4000 rpm, and then dried in an oven at 50° C. for 24 h; the dried sample was ground and sieved with a 100-mesh sieve to obtain brittle starch;

[0089] (3) Disperse 3 g of the brittle starch obtained in step (2), 1 g of xanthan gum, and 1 g of glycerol in 100 mL of deionized water, stir and gelatinize in a 90° C. water bath for 1 h, and cool to 50° C. to obtain a brittle coating film liquid.

[0090] Comparative Example 4

[0091] (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 solution;

[0092] (2) The oxidized corn starch solution of step (1) was cooled at room temperature (25° C.), 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 brittle starch;

[0093] (3) Disperse 3 g of the brittle starch obtained in step (2), 1 g of xanthan gum, and 1 g of glycerol in 100 mL of deionized water, stir and gelatinize in a 90° C. water bath for 1 h, and cool to 50° C. to obtain a brittle coating film liquid.

[0094] Comparative Example 5

[0095] (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;

[0096] (2) The starch solution cross-linked in step (1) was cooled at room temperature (25° C.), and then three times the volume of anhydrous ethanol was added, centrifuged at 4000 rpm, and then dried in an oven at 50° C. for 24 h; the dried sample was ground and sieved with a 100-mesh sieve to obtain brittle starch;

[0097] (3) Disperse 3 g of the brittle starch obtained in step (2), 1 g of xanthan gum, and 1 g of glycerol in 100 mL of deionized water, stir and gelatinize in a 90° C. water bath for 1 h, and cool to 50° C. to obtain a brittle coating film liquid.

[0098] Example 6

[0099] A method for preparing fried chicken nuggets, comprising the following steps:

[0100] (1) Fresh chicken breast was cut into 2 cm × 2 cm × 1 cm blocks, marinated, and then drained. Then, the blocks were soaked in the brittle coating film obtained in Example 1 for 30 seconds, air-dried for 2 minutes, and then coated with a batter. The batter formula was as follows: 20 g corn starch, 20 g flour, 5 g soy protein isolate, 2 g xanthan gum, 1 g salt, 1 g spices, and 100 mL water.

[0101] (2) Frying: Use peanut oil to fry the battered chicken breast pieces at 180°C for 2 minutes, cool for 30 seconds, then fry for 3 minutes, and drain the oil for 10 minutes;

[0102] (3) Freezing: Place the fried chicken pieces in a -18°C refrigerator and freeze for 24 hours.

[0103] Example 7

[0104] A method for preparing fried chicken nuggets, comprising the following steps:

[0105] (1) Fresh chicken breast was cut into 2 cm × 2 cm × 1 cm blocks, marinated, and then drained. Then, the blocks were soaked in the brittle coating film solution obtained in Examples 2 to 5 for 30 seconds, air-dried for 2 minutes, and then coated with a batter. The batter formula was as follows: 20 g corn starch, 20 g flour, 5 g soy protein isolate, 2 g xanthan gum, 1 g salt, 1 g spices, and 100 mL water.

[0106] (2) Frying: Use peanut oil to fry the battered chicken breast pieces at 180°C for 2 minutes, cool for 30 seconds, then fry for 3 minutes, and drain the oil for 10 minutes;

[0107] (3) Freezing: Place the fried chicken pieces in a -18°C refrigerator and freeze for 24 hours.

[0108] Example 8

[0109] A method for preparing fried chicken nuggets, comprising the following steps:

[0110] (1) Fresh chicken breast was cut into 2 cm × 2 cm × 1 cm blocks, marinated, and then drained. Then, the blocks were soaked in the brittle coating film solution obtained in Examples 2 to 5 for 30 seconds, air-dried for 2 minutes, and then coated with a batter. The batter formula was as follows: 20 g corn starch, 20 g flour, 5 g soy protein isolate, 2 g xanthan gum, 1 g salt, 1 g spices, and 100 mL water.

[0111] (2) Frying: Use peanut oil to fry the battered chicken breast pieces at 180°C for 2 minutes, cool for 30 seconds, then fry for 3 minutes, and drain the oil for 10 minutes;

[0112] (3) Freezing: Place the fried chicken pieces in a -18°C refrigerator and freeze for 24 hours.

[0113] Example 9

[0114] A method for preparing fried chicken nuggets, comprising the following steps:

[0115] (1) Fresh chicken breast was cut into 2 cm × 2 cm × 1 cm blocks, marinated, and then drained. Then, the blocks were soaked in the brittle coating film solution obtained in Examples 2 to 5 for 30 seconds, air-dried for 2 minutes, and then coated with a batter. The batter formula was as follows: 20 g corn starch, 20 g flour, 5 g soy protein isolate, 2 g xanthan gum, 1 g salt, 1 g spices, and 100 mL water.

[0116] (2) Frying: Use peanut oil to fry the battered chicken breast pieces at 180°C for 2 minutes, cool for 30 seconds, then fry for 3 minutes, and drain the oil for 10 minutes;

[0117] (3) Freezing: Place the fried chicken pieces in a -18°C refrigerator and freeze for 24 hours.

[0118] Example 10

[0119] A method for preparing fried chicken nuggets, comprising the following steps:

[0120] (1) Fresh chicken breast was cut into 2 cm × 2 cm × 1 cm blocks, marinated, and then drained. Then, the blocks were soaked in the brittle coating film solution obtained in Examples 2 to 5 for 30 seconds, air-dried for 2 minutes, and then coated with a batter. The batter formula was as follows: 20 g corn starch, 20 g flour, 5 g soy protein isolate, 2 g xanthan gum, 1 g salt, 1 g spices, and 100 mL water.

[0121] (2) Frying: Use peanut oil to fry the battered chicken breast pieces at 180°C for 2 minutes, cool for 30 seconds, then fry for 3 minutes, and drain the oil for 10 minutes;

[0122] (3) Freezing: Place the fried chicken pieces in a -18°C refrigerator and freeze for 24 hours.

[0123] Comparative Example 6

[0124] A method for preparing fried chicken nuggets, comprising the following steps:

[0125] (1) Fresh chicken breasts were cut into 2 cm × 2 cm × 1 cm blocks, marinated, and then drained. The blocks were then immersed in the brittle coating solution obtained in Comparative Example 1 for 30 seconds, air-dried for 2 minutes, and then coated with a batter. The batter formula was as follows: 20 g corn starch, 20 g flour, 5 g soy protein isolate, 2 g xanthan gum, 1 g salt, 1 g spices, and 100 mL water.

[0126] (2) Frying: Use peanut oil to fry the battered chicken breast pieces at 180°C for 2 minutes, cool for 30 seconds, then fry for 3 minutes, and drain the oil for 10 minutes;

[0127] (3) Freezing: Place the fried chicken pieces in a -18°C refrigerator and freeze for 24 hours.

[0128] Comparative Example 7

[0129] A method for preparing fried chicken nuggets, comprising the following steps:

[0130] (1) Fresh chicken breasts were cut into 2 cm × 2 cm × 1 cm blocks, marinated, and then drained. The blocks were then soaked in the brittle coating solution obtained in Comparative Example 2 for 30 seconds, air-dried for 2 minutes, and then coated with a batter. The batter formula was as follows: 20 g corn starch, 20 g flour, 5 g soy protein isolate, 2 g xanthan gum, 1 g salt, 1 g spices, and 100 mL water.

[0131] (2) Frying: Use peanut oil to fry the battered chicken breast pieces at 180°C for 2 minutes, cool for 30 seconds, then fry for 3 minutes, and drain the oil for 10 minutes;

[0132] (3) Freezing: Place the fried chicken pieces in a -18°C refrigerator and freeze for 24 hours.

[0133] Comparative Example 8

[0134] A method for preparing fried chicken nuggets, comprising the following steps:

[0135] (1) Fresh chicken breasts were cut into 2 cm × 2 cm × 1 cm blocks, marinated, and then drained. The blocks were then soaked in the brittle coating solution obtained in Comparative Example 3 for 30 seconds, air-dried for 2 minutes, and then coated with a batter. The batter formula was as follows: 20 g corn starch, 20 g flour, 5 g soy protein isolate, 2 g xanthan gum, 1 g salt, 1 g spices, and 100 mL water.

[0136] (2) Frying: Use peanut oil to fry the battered chicken breast pieces at 180°C for 2 minutes, cool for 30 seconds, then fry for 3 minutes, and drain the oil for 10 minutes;

[0137] (3) Freezing: Place the fried chicken pieces in a -18°C refrigerator and freeze for 24 hours.

[0138] Comparative Example 9

[0139] A method for preparing fried chicken nuggets, comprising the following steps:

[0140] (1) Fresh chicken breasts were cut into 2 cm × 2 cm × 1 cm blocks, marinated, and then drained. The blocks were then soaked in the brittle coating solution obtained in Comparative Example 4 for 30 seconds, air-dried for 2 minutes, and then coated with a batter. The batter formula was as follows: 20 g corn starch, 20 g flour, 5 g soy protein isolate, 2 g xanthan gum, 1 g salt, 1 g spices, and 100 mL water.

[0141] (2) Frying: Use peanut oil to fry the battered chicken breast pieces at 180°C for 2 minutes, cool for 30 seconds, then fry for 3 minutes, and drain the oil for 10 minutes;

[0142] (3) Freezing: Place the fried chicken pieces in a -18°C refrigerator and freeze for 24 hours.

[0143] Comparative Example 10

[0144] A method for preparing fried chicken nuggets, comprising the following steps:

[0145] (1) Cut fresh chicken breast into 2 cm × 2 cm × 1 cm blocks, marinate, drain, and then soak in the brittle coating film solution obtained in Comparative Example 5 for 30 seconds, air-dry for 2 minutes, and then coat with a batter; wherein the batter formula is: 20 g corn starch, 20 g flour, 5 g soy protein isolate, 2 g xanthan gum, 1 g salt, 1 g spices, and 100 mL water;

[0146] (2) Frying: Use peanut oil to fry the battered chicken breast pieces at 180°C for 2 minutes, cool for 30 seconds, then fry for 3 minutes, and drain the oil for 10 minutes;

[0147] (3) Freezing: Place the fried chicken pieces in a -18°C refrigerator and freeze for 24 hours.

[0148] Result Analysis

[0149] 1. 30 g of the film solutions prepared in Examples 1 to 5 and Comparative Examples 1 to 5 were weighed and poured onto a polytetrafluoroethylene flat plate using a casting method. The flat plate was then dried in a 50°C oven for 8 hours. The flat plate was peeled off and subjected to humidity equilibration at 50% humidity for 24 hours to obtain a coating film. The water permeability of the coating film was measured. The results are shown in Table 1.

[0150] Table 1. Test results of water vapor transmission rate of coating

[0151]

[0152] 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 and thus improving the film's water barrier properties. Among them, Example 1 exhibits the lowest water transmission rate, indicating that the coating film prepared using oxidized corn starch as the raw material and undergoing a 3-hour cross-linking reaction has better water barrier properties.

[0153] 2. The fried chicken nuggets of Examples 6 to 10 and Comparative Examples 6 to 10 were heated at a microwave power of 700 W for 2 minutes. After microwave heating, the brittleness was measured. The results are shown in Table 2:

[0154] 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.

[0155] Table 2. Results of brittleness test on microwaveable frozen pre-fried foods

[0156]

[0157]

[0158] As shown in Table 2, the crispness of the microwaveable frozen pre-fried foods in Examples 6-10 was significantly improved compared to Comparative Examples 6-10. Compared to Comparative Example 7, the crispness of the food in Example 6 was increased by 47.3%. This indicates that the crispening coating in Example 1 has a good effect on improving the crispness of microwaveable frozen pre-fried foods.

[0159] 3. The color of fried foods after frying and microwave reheating was measured. The results are shown in Table 3:

[0160]

[0161] Table 3. Color test results of microwaveable frozen pre-fried foods

[0162] As shown in Table 3, compared to Comparative Examples 6-10, the frozen pre-fried chicken nuggets using the brittle coatings of Examples 6-10 exhibited higher L* and b* values, greater brightness, and a golden color, demonstrating that the brittle coating prepared with calcium-crosslinked starch can effectively improve the color quality of frozen pre-fried chicken nuggets. Among them, Example 1 exhibited the highest L* and b* values, indicating that the coating film prepared with oxidized corn starch can better improve the color quality of frozen pre-fried chicken nuggets compared to corn starch.

[0163] 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 are also within the scope of protection defined by the claims of the present invention.

Claims

1. A brittle coating for microwaveable frozen pre-fried foods, characterized in that: The raw materials of the brittle coating include, by mass, 3 to 6 parts of brittle starch, 1 to 3 parts of hydrophilic colloid, 1 to 3 parts of glycerol, and 100 to 300 parts of water. The preparation of the brittle starch 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 performing alcohol precipitation, centrifugation, drying, crushing, and sieving to obtain the brittle starch. The pH value for adjusting the pH to alkaline is 8 to 10.

2. The embrittled coating according to claim 1, characterized in that The raw materials of the brittle coating include, by weight, 3 to 5 parts of brittle starch, 1 to 2 parts of hydrophilic colloid, 1 to 2 parts of glycerol, and 100 to 200 parts of water. The preparation of the brittle starch 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 performing alcohol precipitation, centrifugation, drying, crushing, and sieving to obtain the brittle starch. The pH value for adjusting the pH to alkaline is 8 to 10.

3. The embrittled coating according to claim 1, characterized in that The raw materials of the brittle coating include, by mass, 3 parts of brittle starch, 1 part of hydrophilic colloid, 1 part of glycerol, and 100 parts of water. The preparation of the brittle starch 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 brittle starch through alcohol precipitation, centrifugation, drying, crushing, and sieving. The pH value for adjusting the pH to alkaline is 8 to 10.

4. The embrittled coating 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 embrittled coating according to claim 1, characterized in that The pH is adjusted to an alkaline pH of 9.

6. The embrittled coating according to claim 1, characterized in that 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.

7. The embrittled coating according to claim 1, characterized in that 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.

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

9. The embrittled coating according to claim 1, characterized in that The temperature of the calcium ion cross-linking modification is 50° C. and the time is 3 hours.

10. The embrittled coating according to claim 1, characterized in that The centrifugal speed is 3500-4000 rpm, and the time is 10-15 minutes.

11. The embrittled coating according to claim 1, characterized in that The drying temperature is 40-50° C., and the drying time is 12-36 hours.

12. The embrittled coating according to claim 1, characterized in that The mesh number of the sieving sieve is 100 to 200 meshes.

13. The embrittled coating according to any one of claims 1 to 3, characterized in that: The hydrophilic colloid includes one or more of xanthan gum, carrageenan, guar gum and pectin.

14. A method for preparing the embrittled coating according to any one of claims 1 to 13, characterized in that: The method comprises dispersing brittle starch in deionized water, adding hydrophilic colloid and glycerin, stirring evenly, heating for gelatinization, and then stirring and cooling to obtain a brittle coating film liquid.

15. The method according to claim 14, characterized in that The gelatinization temperature is 80-100°C.

16. The method according to claim 14, characterized in that The gelatinization time is 30 to 60 minutes.

17. Use of the embrittled coating according to any one of claims 1 to 13 in the fields of food, medicine, feed and chemical materials.

18. A method for preparing microwaveable frozen pre-fried chicken nuggets, characterized in that: The method comprises the following steps: soaking the pre-treated chicken pieces in the brittle coating film liquid prepared according to claim 14, taking out the chicken pieces, draining the chicken pieces, coating the chicken pieces with batter, and frying the chicken pieces; and placing the chicken pieces in a refrigerator for refrigeration after frying.

19. A fried chicken nugget that can be re-crisped in a microwave, characterized in that: The fried chicken nuggets are prepared by the preparation method according to claim 18.

20. A method for improving the crispness of frozen fried food after microwave reheating, characterized in that: The method comprises soaking the fried food in the brittle coating film liquid prepared according to claim 14, air-drying the food, and then coating the food with batter, frying the food, freezing the food, and reheating the food in microwave ovens.

21. The method according to claim 20, characterized in that The soaking time is 30 to 60 seconds.

22. The method according to claim 20, characterized in that The microwave reheating power is 700-800W, and the heating time is 2-3 minutes.

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