Double-skinned fried milk and a preparation method thereof

Abstract

The present application belongs to the field of food processing technology, and particularly relates to a kind of fried double skin milk and a preparation method thereof.The fried double skin milk is prepared from the following raw materials by weight: water 20-40 parts, natural starch 5-15 parts, modified starch 2-8 parts, white granulated sugar 5-20 parts, edible salt 0.2-1 part, milk 1-10 parts, full-fat milk powder 2-10 parts, artificial butter 2-10 parts, edible glue 0.1-1 part, horse hoof 10-30 parts, milk flavor 0.1-1 part.The present application is fully mechanized and coherent production, and the prepared fried double skin milk has the characteristic aroma and flavor of double skin milk, rich and harmonious milk flavor, smooth taste, fine and dense organization, no hole, stable product quality, and is not easy to burst during the process of re-frying.

Description

Technical Field

[0001] This invention belongs to the field of food processing technology, specifically relating to a fried double-skin milk pudding and its preparation method. Background Technology

[0002] Double-skin milk pudding is a dessert made primarily from fresh milk and glutinous rice or starch. It retains the nutritional components of fresh milk. After frying, the outer layer is crispy yet not hard, while the inner layer is tender and delicious, with a fresh milk flavor.

[0003] Traditional handmade fried double-skin milk pudding is complex, time-consuming, and difficult to store. The industrial processing method for fried double-skin milk pudding mentioned in related technologies includes the following steps: filling preparation involves mixing and high-temperature heating, rapid cooling to 0℃-10℃, and cutting into pieces; skin preparation involves mixing and fermenting, adding water and stirring; filling is coated with skin, fried, cooled, and packaged. While this process allows for mechanized industrial production, it suffers from the following problems: After mixing and high-temperature heating, the filling needs to be poured into molds to cool and set before cutting into pieces. The cooling process is time-consuming, requires refrigerated space in the factory for turnover, and the filling is easily damaged during demolding, affecting yield. Due to the special nature of the filling's material and structure, the cutting process has low mechanization and is prone to damage, further impacting yield; the skin preparation requires a fermentation process, affecting production efficiency. Summary of the Invention

[0004] The present invention aims to at least partially solve one of the technical problems in the related art. To this end, the present invention provides fried double-skin milk and its preparation method suitable for industrial mechanized production.

[0005] To achieve the above-mentioned objectives of this invention, the following technical solution is adopted:

[0006] This invention provides a method for preparing fried double-skin milk suitable for industrial mechanized production. The fried double-skin milk is prepared from the following raw materials in parts by weight: 20-40 parts water, 5-15 parts natural starch, 2-8 parts modified starch, 5-20 parts white sugar, 0.2-1 part edible salt, 1-10 parts condensed milk, 2-10 parts whole milk powder, 2-10 parts margarine, 0.1-1 part edible gum, 10-30 parts water chestnut, and 0.1-1 part milk flavoring.

[0007] The method for preparing fried double-skin milk includes the following steps:

[0008] (1) Starch gelatinization: Mix some water, some natural starch, some modified starch and edible gum first, then add the remaining water and melted margarine and mix evenly. Stir and heat until the gelatinized product reaches a temperature of 71-75℃. Remove from the pot and cool to below 50℃ to obtain gelatinized starch.

[0009] (2) CO2 mixing: First, add the water chestnut slices to the CO2 mixer and crush them at a speed of 75 r / min for 1-3 min. Then add the gelatinized starch and milk flavoring from step (1) and mix until uniform. Then add salt, white sugar, whole milk powder and condensed milk. Finally, add the remaining natural starch and modified starch and mix evenly. Then, vacuum and mix at a speed of 75 r / min until the vacuum degree reaches -0.8 bar and the gas returns to zero. Connect the CO2 exhaust pipe and mix while blowing CO2. The discharge temperature is controlled at -5 to -7℃. Vacuum again and mix while vacuuming at a speed of 75 r / min until the vacuum degree reaches -0.8 bar and the gas returns to zero. Discharge the material and store it in the cold storage for later use.

[0010] (3) Molding: The material from step (2) is fed into the hopper of the molding machine by the elevator, and the molding machine and mold are used to form a complete shape to obtain the shaped material;

[0011] (4) Coating: The first slurry is prepared by mixing the coating powder and ice water at a mass ratio of 1:1.5. The second slurry is prepared by mixing the coating powder and ice water at a mass ratio of 1:1.15. The temperature is controlled at 2-6℃. The first slurry is introduced into the spray coating machine and coated onto the surface of the shaped material. Then, the material is coated with powder by the powder coating machine. The second slurry is introduced into the submersible coating machine and coated onto the surface of the powder-coated material.

[0012] (5) Pre-frying, quick-freezing and packaging: The material processed in step (4) is pre-fried at 190°C for 20-30 seconds, then rapidly frozen at -32°C to a core temperature of -18°C or below, and then packaged.

[0013] In some embodiments of the present invention, the natural starch is one or more of corn starch, tapioca starch, and potato starch.

[0014] In some embodiments of the present invention, the modified starch is one or more of physically modified starch, chemically modified starch, enzymatically modified starch, and compound modified starch.

[0015] In some embodiments of the present invention, the edible gum is one or more of agar, xanthan gum, gelatin, carrageenan, and guar gum.

[0016] In some embodiments, the natural starch gelatinized in step (1) accounts for 40%-60% of the total natural starch; the modified starch gelatinized accounts for 40%-60% of the total modified starch.

[0017] In some embodiments, the water chestnut slices need to be thawed and drained in advance, and the temperature should be controlled between -2°C and 0°C.

[0018] In some embodiments, the time from the addition of salt to the mixing of the remaining natural starch and modified starch is controlled at 3-4 minutes to ensure that the components are fully and evenly mixed.

[0019] In some embodiments, the molding weight of step (3) is controlled at 135-145g / 10 pieces.

[0020] In some embodiments, the coating composition in step (4) is: 50-70 parts high-gluten flour, 20-30 parts natural starch, 0.5-1.5 parts baking soda, 0.5-1.5 parts sodium pyrophosphate, and 0.1-1 parts spices; the parts are by weight.

[0021] In some embodiments, the natural starch in the coating composition is selected from one or more of corn starch, tapioca starch, and potato starch.

[0022] In some embodiments, the spices in the coating powder are selected from one or both of white pepper powder and garlic powder.

[0023] This invention also provides fried double-skin milk prepared by the above preparation method.

[0024] The present invention has the following advantages and beneficial effects:

[0025] 1) The present invention is a method for preparing fried double-skin milk suitable for industrial mechanized production. The entire production process is mechanized and continuous. The material is cooled and slowly frozen by a CO2 mixer, molded by a forming machine, and directly linked by a chain to the subsequent coating, pre-frying, and quick-freezing, which can realize continuous production.

[0026] 2) This invention provides a method for preparing fried double-skin milk suitable for industrial mechanized production. It improves upon the previous method, which required cooling a paste to 0℃-10℃ to form blocks, and then cutting them into small cubes as filling for industrial-scale production of fried double-skin milk. This significantly saves time and reduces material loss during processing.

[0027] 3) The fried double-skin milk prepared by the method of the present invention has the characteristic aroma and fragrance of double-skin milk, with a rich and harmonious milky aroma, smooth taste, fine texture, no holes, stable product quality, and is not prone to bursting during the refrying process.

[0028] 4) In the recipe for fried double-skin milk pudding of this invention, a combination of natural starch and modified starch is chosen primarily because: natural starch is inexpensive and, after gelatinization, has a smooth texture that matches the characteristics of double-skin milk pudding. However, during industrial production, the starch granules of natural starch are prone to breakage during gelatinization, making it difficult to retain moisture in the texture. Modified starch, on the other hand, has good heat resistance. When used in conjunction with natural starch, it ensures a relatively large number of intact starch granules during the gelatinization stage of the double-skin milk pudding, thereby retaining moisture and resulting in a smooth texture and less tendency for the pudding to burst when re-fried. Modified starch also has better freezing properties. When used in conjunction with natural starch, it compensates for the natural starch's poor freeze resistance, improving the product's quality stability during storage.

[0029] 5) In the preparation method of fried double-skin milk in this embodiment of the invention, only a portion of the starch (natural starch + modified starch) is gelatinized. The purpose of this is that the gelatinized starch absorbs water to form a carrier that carries the flavor of the double-skin milk, which is beneficial to the implementation of subsequent steps (3), (4), and (5). The remaining ungelatinized starch (natural starch + modified starch) can continuously absorb the water lost by the gelatinized starch particles during mixing, shaping, coating, pre-frying, quick-freezing, and refrying by consumers, so as to maintain the stability of the double-skin milk system.

[0030] 6) This invention is suitable for industrial mechanized production of fried double-skin milk. Water chestnuts are added when processing the filling, which is not only crisp and refreshing and relieves greasiness, but also solves the problem of easy bursting of filling when fried desserts are re-fried. Attached Figure Description

[0031] Figure 1 Sensory evaluation radar charts for Example 1 and Comparative Examples 1-6;

[0032] Figure 2 The changes in water separation rate in Example 1 and Comparative Examples 1-6 after freeze-thaw cycles are shown. Detailed Implementation

[0033] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0034] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0035] Unless otherwise stated, the scientific and technical terms used herein have the meanings commonly understood by those skilled in the art.

[0036] When a value is described as a range, it should be understood that such disclosure includes disclosure of all possible subranges within that range, as well as the specific numerical value falling within that range, regardless of whether the specific numerical value or specific subrange is explicitly specified.

[0037] The natural starch involved in Examples 1-5 and Comparative Examples 1-6 of this invention is a mixture of corn starch and tapioca starch (mass ratio 2:1), and the modified starch is physically modified corn starch, all of which are commercially available products.

[0038] Example 1:

[0039] A type of fried double-skin milk suitable for industrial mechanized production is prepared from the following raw materials in parts by weight: 30 parts water, 8 parts natural starch, 8 parts modified starch, 10 parts white sugar, 0.4 parts edible salt, 6 parts condensed milk, 4 parts whole milk powder, 8 parts margarine, 0.3 parts edible gum, 15 parts water chestnut, and 0.2 parts milk flavoring.

[0040] The above method for preparing fried double-skin milk includes the following steps:

[0041] (1) Starch gelatinization: Mix some water, some natural starch (accounting for 50% of all natural starch), some modified starch (accounting for 50% of all modified starch) and edible gum first, then add the remaining water and melted margarine and mix evenly. Stir and heat until the gelatinized product reaches a temperature of 71-75℃, remove from the pot and cool to below 50℃ to obtain gelatinized starch.

[0042] (2) CO2 mixing: First, add the water chestnut slices (water chestnut slices need to be thawed and drained in advance, and the temperature is controlled at -2 to 0℃) to the CO2 mixer and crush them at 75 r / min for 3 min. Then add the gelatinized starch and milk flavoring from step (1) and mix until uniform. Then add salt, white sugar, whole milk powder and condensed milk. Finally, add the remaining natural starch and modified starch and mix evenly (control the time at 3.5 min). Then, while vacuuming, mix at 75 r / min until the vacuum degree reaches -0.8 bar and return to zero. Connect the CO2 exhaust pipe (inject CO2 in small amounts and multiple times) and mix while injecting CO2. The discharge temperature is controlled at -5 to -7℃. Vacuum again and mix while vacuuming at 75 r / min until the vacuum degree reaches -0.8 bar and return to zero. Discharge the material and store it in the cold storage for later use.

[0043] (3) Molding: The material from step (2) is added to the hopper of the molding machine by the elevator, and the molding machine and mold are used to make a complete shape (the molding weight is controlled at 135-145g / 10 pieces) to obtain the molded material;

[0044] (4) Coating: The first slurry is prepared by mixing the coating powder and ice water at a mass ratio of 1:1.5. The second slurry is prepared by mixing the coating powder and ice water at a mass ratio of 1:1.15. The temperature is controlled at 2-6℃. The first slurry is introduced into the spray coating machine and coated onto the surface of the shaped material. Then, the material is coated with powder by the powder coating machine. The second slurry is introduced into the submersible coating machine and coated onto the surface of the powder-coated material.

[0045] (5) Pre-frying, quick-freezing and packaging: The material processed in step (4) is pre-fried at 190°C for 20-30 seconds, then rapidly frozen at -32°C to a core temperature of -18°C or below, and then packaged.

[0046] The coating in step (4) consists of: 60 parts high-gluten flour, 25 parts natural starch (corn starch), 1 part baking soda, 1 part sodium pyrophosphate, and 0.3 parts spices (white pepper powder); the parts are by weight.

[0047] Example 2

[0048] A type of fried double-skin milk suitable for industrial mechanized production is prepared from the following raw materials in parts by weight: 35 parts water, 12 parts natural starch, 5 parts modified starch, 8 parts white sugar, 0.5 parts edible salt, 5 parts condensed milk, 6 parts whole milk powder, 4 parts margarine, 0.4 parts edible gum, 14 parts water chestnut, and 0.2 parts milk flavoring.

[0049] The preparation method is the same as in Example 1.

[0050] Example 3

[0051] A type of fried double-skin milk suitable for industrial mechanized production is prepared from the following raw materials in parts by weight: 30 parts water, 10 parts natural starch, 6 parts modified starch, 10 parts white sugar, 0.4 parts edible salt, 5 parts condensed milk, 5 parts whole milk powder, 5 parts margarine, 0.6 parts edible gum, 13 parts water chestnut, and 0.4 parts milk flavoring.

[0052] The preparation method is the same as in Example 1.

[0053] Example 4

[0054] A type of fried double-skin milk suitable for industrial mechanized production is prepared from the following raw materials in parts by weight: 35 parts water, 15 parts natural starch, 2 parts modified starch, 6 parts white sugar, 0.4 parts edible salt, 6 parts condensed milk, 6 parts whole milk powder, 6 parts margarine, 0.3 parts edible gum, 20 parts water chestnut, and 0.6 parts milk flavoring.

[0055] The preparation method is the same as in Example 1.

[0056] Example 5

[0057] A type of fried double-skin milk suitable for industrial mechanized production is prepared from the following raw materials in parts by weight: 40 parts water, 15 parts natural starch, 4 parts modified starch, 10 parts white sugar, 0.6 parts edible salt, 6 parts condensed milk, 8 parts whole milk powder, 4 parts margarine, 0.2 parts edible gum, 25 parts water chestnut, and 0.4 parts milk flavoring.

[0058] The preparation method is the same as in Example 1.

[0059] It should be noted that the following comparative examples are not prior art, but are only set up for comparison with the examples and are not intended to limit the present invention.

[0060] Comparative Example 1

[0061] The recipe for fried double-skin milk is the same as in Example 1;

[0062] The preparation method of the fried double-skin milk pudding in Comparative Example 1 includes the following steps:

[0063] (1) Starch gelatinization: Mix some water, natural starch, modified starch and edible gum first, then add the remaining water and melted margarine and mix evenly. Stir and heat until the gelatinized product reaches a temperature of 71-75℃. Remove from the pot and cool to below 50℃ to obtain gelatinized starch.

[0064] (2) CO2 mixing: First, add the water chestnut slices (the water chestnut slices need to be thawed and drained in advance, and the temperature is controlled at -2 to 0℃) to the CO2 mixer and crush them at 75 r / min for 3 min. Then add the gelatinized starch and milk flavoring from step (1) and mix until uniform. Then add salt, white sugar, whole milk powder and condensed milk and mix evenly (control the time at 3.5 min). Then mix while vacuuming at 75 r / min until the vacuum degree reaches -0.8 bar and the gas returns to zero. Connect the CO2 exhaust pipe (inject CO2 in small amounts and multiple times) and mix while injecting CO2. The discharge temperature is controlled at -5 to -7℃. Vacuum again while vacuuming and mixing at 75 r / min until the vacuum degree reaches -0.8 bar and the gas returns to zero. Discharge the material and store it in the cold storage for later use.

[0065] (3) Molding: The material from step (2) is added to the hopper of the molding machine by the elevator, and the molding machine and mold are used to make a complete shape (the molding weight is controlled at 135-145g / 10 pieces) to obtain the molded material;

[0066] (4) Coating: The first slurry is prepared by mixing the coating powder and ice water at a mass ratio of 1:1.5. The second slurry is prepared by mixing the coating powder and ice water at a mass ratio of 1:1.15. The temperature is controlled at 2-6℃. The first slurry is introduced into the spray coating machine and coated onto the surface of the shaped material. Then, the material is coated with powder by the powder coating machine. The second slurry is introduced into the submersible coating machine and coated onto the surface of the powder-coated material.

[0067] (5) Pre-frying, quick-freezing and packaging: The material processed in step (4) is pre-fried at 190°C for 20-30 seconds, then rapidly frozen at -32°C to a core temperature of -18°C or below, and then packaged.

[0068] The coating in step (4) consists of: 60 parts high-gluten flour, 25 parts natural starch (corn starch), 1 part baking soda, 1 part sodium pyrophosphate, and 0.3 parts spices (white pepper powder); the parts are by weight.

[0069] A comparison of Example 1 and Comparative Example 1 shows that the difference is that in Comparative Example 1, all natural and modified starches were gelatinized during the preparation process. The product of Comparative Example 1 is prone to frying and bursting, with severe damage to the starch granules and an inability to retain water.

[0070] Comparative Example 2

[0071] The fried double-skin milk in Comparative Example 2 was prepared from the following ingredients in parts by weight: 30 parts water, 16 parts natural starch, 10 parts white sugar, 0.4 parts edible salt, 6 parts condensed milk, 4 parts whole milk powder, 8 parts margarine, 0.3 parts edible gum, 15 parts water chestnut, and 0.2 parts milk flavoring.

[0072] The preparation method for fried double-skin milk is the same as in Example 1.

[0073] A comparison of Example 1 and Comparative Example 2 shows that the difference is that the recipe for fried double-skin milk pudding in Comparative Example 2 does not contain modified starch, and the amount of natural starch used is greater than that in Example 1. The product of Comparative Example 2 is prone to bursting during frying and has a poor texture. In contrast, Example 1, due to the addition of modified starch, has better high-temperature and freezing resistance, which improves the product's quality stability during storage.

[0074] Comparative Example 3

[0075] The fried double-skin milk in Comparative Example 3 was prepared from the following ingredients in parts by weight: 30 parts water, 8 parts natural starch, 8 parts modified starch, 10 parts white sugar, 0.4 parts edible salt, 6 parts condensed milk, 4 parts whole milk powder, 8 parts margarine, 0.3 parts edible gum, and 0.2 parts milk flavoring.

[0076] The preparation method for fried double-skin milk is the same as in Example 1.

[0077] A comparison of Example 1 and Comparative Example 3 shows that the recipe for fried double-skin milk pudding in Comparative Example 3 does not contain water chestnuts. Therefore, the milk pudding in Comparative Example 3 is prone to bursting during frying. In contrast, Example 1, because a certain amount of water chestnuts was added, maintains its volume during frying, thus inhibiting the bursting phenomenon.

[0078] Comparative Example 4

[0079] The recipe for fried double-skin milk in Comparative Example 4 is as follows: 30 parts water, 8 parts natural starch, 1 part modified starch, 10 parts white sugar, 0.4 parts edible salt, 6 parts condensed milk, 4 parts whole milk powder, 8 parts margarine, 0.3 parts edible gum, 15 parts water chestnut, and 0.2 parts milk flavoring.

[0080] The preparation method for fried double-skin milk is the same as in Example 1.

[0081] A comparison between Example 1 and Comparative Example 4 shows that although Comparative Example 4 contains modified starch, the content is low. The product in Comparative Example 4 is prone to bursting during frying and has a poor texture. In contrast, Example 1, with its appropriate modified starch content, combined with natural starch, improves product quality and stability during production and storage.

[0082] Comparative Example 5

[0083] The fried double-skin milk pudding in Comparative Example 5 is made from the following ingredients in parts by weight: 30 parts water, 8 parts natural starch, 8 parts modified starch, 10 parts white sugar, 0.4 parts edible salt, 6 parts condensed milk, 4 parts whole milk powder, 8 parts margarine, 15 parts water chestnuts, and 0.2 parts milk flavoring.

[0084] The preparation method for fried double-skin milk is the same as in Example 1.

[0085] A comparison between Example 1 and Comparative Example 5 shows that the formula of Comparative Example 5 does not contain edible gum. The product of Comparative Example 5 is prone to bursting when fried and has a less smooth texture. In contrast, the addition of edible gum in Example 1 makes the double-skin milk pudding smoother and improves the water-holding capacity of the starch system in the filling, thus enhancing system stability and inhibiting bursting.

[0086] Comparative Example 6

[0087] The fried double-skin milk pudding in Comparative Example 6 is made from the following ingredients in parts by weight: 30 parts water, 8 parts natural starch, 8 parts modified starch, 10 parts white sugar, 0.4 parts edible salt, 6 parts condensed milk, 4 parts whole milk powder, 8 parts margarine, 0.3 parts edible gum, and 15 parts water chestnut.

[0088] The preparation method for fried double-skin milk is the same as in Example 1.

[0089] A comparison between Example 1 and Comparative Example 6 shows that Comparative Example 6's formula does not contain milk flavoring. The aroma and fragrance scores of Comparative Example 6's product are significantly lower. In contrast, the addition of milk flavoring in Example 1 makes the aroma and fragrance of the double-skin milk pudding more appealing.

[0090] Product performance testing

[0091] 1. Sensory analysis:

[0092] Quantitative descriptive sensory analysis was employed using a 10-point scale ("0" represents none, "10" represents the strongest). Fifteen individuals (5 men and 10 women, aged 25-30) with relevant professional experience were selected. Each sample was tested three times, with mouth rinsing with deionized water between consecutive tastings. Evaluators were trained according to ISO 8589 (2007) standards and evaluated six sensory attributes: aroma, flavor, mouthfeel, texture, and likability. A comparative analysis was conducted between Example 1 of this invention and Comparative Examples 1-6. The scoring method is shown in Table 1, the scoring results are shown in Table 2, and the sensory evaluation radar chart is shown below. Figure 1 .

[0093] Table 1 Sensory evaluation methods

[0094]

[0095] Table 2 Sensory evaluation results

[0096] Scoring Items Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 aroma 9.0 8.5 9.0 9.0 8.5 9.0 6.0 fragrance 9.0 9.0 8.5 9.0 9.0 9.0 7.0 taste 9.5 5.0 6.0 8.5 6.0 7.0 9.0 Organizational status 9.0 3.0 5.0 4.0 5.0 6.0 9.0 Popularity 10.0 5.0 6.0 6.0 6.0 7.0 6.0

[0097] 2. Water retention rate:

[0098] The moisture content of seven samples was determined according to the national food safety standard GB 5009.3-2016, "Determination of Moisture in Food". Frozen double-skin milk will lose moisture during the frying process; the ratio of moisture content before and after frying is the water retention rate.

[0099] Table 3. Water retention rates of Example 1 and Comparative Examples 1-6 after frying.

[0100]

[0101] Table 3 shows that Example 1 had the highest water retention rate, while Comparative Example 1 had the lowest. This may be because all the natural and modified starches in Comparative Example 1 were gelatinized, leading to severe damage to the starch granules during subsequent processing, making them unable to retain water. A comprehensive analysis of the differences in water retention rates between Example 1 and the six comparative examples reveals the following order of influence on water retention rate: complete starch gelatinization > no modified starch added > low modified starch content > no water chestnuts > no edible gums > milk flavoring.

[0102] 3. Freeze-thaw stability

[0103] Freeze-thaw stability refers to the stability of double-skin milk when subjected to alternating freezing and thawing.

[0104] The water separation rate was chosen as the indicator for freeze-thaw stability. The lower the water separation rate, the better the freeze-thaw stability of the sample.

[0105] 3.1 Sample freezing and thawing methods

[0106] The quick-frozen double-skin milk samples from Example 1 and Comparative Examples 1-6 were vacuum-sealed into sealed bags and placed at -18 to -20°C for 24 hours. After removal, the samples were thawed at room temperature for 3 hours, heated in a water bath at 95°C for 5 minutes, cooled to room temperature, and their parameters were measured.

[0107] 3.2 Method for determining water separation rate

[0108] Weigh appropriate amounts of the quick-frozen double-skin milk samples from Example 1 and Comparative Examples 1, 2, 3, 4, 5, and 6 into centrifuge tubes, centrifuge at 4000 r / min for 20 min, remove excess water, and weigh. Repeat the experiment three times.

[0109] Water separation rate = (m1 + m2 - m3) / m1 × 100%

[0110] In the formula: m1 is the sample mass / g; m2 is the mass of the centrifuge tube / g; m3 is the total mass of the centrifuge tube and the precipitate after centrifugation / g.

[0111] The trend of water separation rate of double-skin milk samples after different freeze-thaw cycles is as follows: Figure 2 As shown, the data is presented in Table 4.

[0112] Table 4. Water separation rate of different samples from Example 1 and Comparative Examples 1-6 after different freeze-thaw cycles.

[0113] Water separation rate (%) Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Freeze-thaw cycles -1 2.00 6.50 6.00 4.00 5.50 3.50 2.00 Freeze-thaw cycles -2 4.50 7.00 6.20 5.10 5.80 4.60 4.40 Freeze-thaw cycles -3 5.00 8.00 7.00 5.60 6.40 5.30 5.10 Freeze-thaw cycles -4 5.40 8.20 7.40 6.00 7.00 5.60 5.50 Freeze-thaw cycles -5 6.20 8.50 7.90 6.40 7.50 6.30 6.10 Freeze-thaw cycles -6 6.30 9.00 8.40 7.20 8.10 6.70 6.30

[0114] pass Figure 2As shown in Table 4, the water separation rate of Example 1 was lower than that of Comparative Examples 1-5, and was directly proportional to the number of freeze-thaw cycles. Comparative Example 6 showed that the milk flavoring had almost no effect on the freeze-thaw stability of the samples. Comparative Example 5 showed that the addition of edible gum improved freeze-thaw stability while reducing the water separation rate. Edible gum helps maintain the moisture state in the composite system, which is related to its rigid helical structure, providing good stability and water retention, or the stable and complex double helix structure formed between the edible gum and starch. In other words, edible gum can chemically bind amylose or amylopectin, making starch less prone to recrystallization and reducing moisture loss from starch granules. A comprehensive analysis of the differences in water separation rate between Example 1 and the 6 comparative examples reveals that the order of influence of water separation rate factors is: complete starch gelatinization > no added modified starch > low modified starch content > no water chestnut > no edible gum > milk flavoring, consistent with the trend in index 2, water retention rate.

[0115] The increased number of freeze-thaw cycles increases the starch water separation rate, possibly because the starch structure is damaged by the formation of ice crystals from the separated water.

[0116] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0117] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing fried double-skin milk pudding suitable for industrial mechanized production, characterized in that, The fried double-skin milk is prepared from the following ingredients in parts by weight: 20-40 parts water, 5-15 parts natural starch, 2-8 parts modified starch, 5-20 parts white sugar, 0.2-1 part edible salt, 1-10 parts condensed milk, 2-10 parts whole milk powder, 2-10 parts margarine, 0.1-1 part edible gum, 10-30 parts water chestnut, and 0.1-1 part milk flavoring. The method for preparing fried double-skin milk includes the following steps: (1) Starch gelatinization: Mix some water, some natural starch, some modified starch and edible gum first, then add the remaining water and melted margarine and mix evenly. Stir and heat until the gelatinized product reaches a temperature of 71-75℃. Remove from the pot and cool to below 50℃ to obtain gelatinized starch. (2) CO2 mixing: First, add the water chestnut slices to the CO2 mixer and crush them at a speed of 75 r / min for 1-3 min. Then add the gelatinized starch and milk flavoring from step (1) and mix until uniform. Then add salt, white sugar, whole milk powder and condensed milk. Finally, add the remaining natural starch and modified starch and mix evenly. Then, vacuum and mix at a speed of 75 r / min until the vacuum degree reaches -0.8 bar and the gas returns to zero. Connect the CO2 exhaust pipe and mix while blowing CO2. The discharge temperature is controlled at -5 to -7℃. Vacuum again and mix while vacuuming at a speed of 75 r / min until the vacuum degree reaches -0.8 bar and the gas returns to zero. Discharge the material and store it in the cold storage for later use. (3) Molding: The material from step (2) is fed into the hopper of the molding machine by the elevator, and the molding machine and mold are used to form a complete shape to obtain the shaped material; (4) Coating: The first slurry is prepared by mixing the coating powder and ice water at a mass ratio of 1:1.

5. The second slurry is prepared by mixing the coating powder and ice water at a mass ratio of 1:1.

15. The temperature is controlled at 2-6℃. The first slurry is introduced into the spray coating machine and coated onto the surface of the shaped material. Then, the material is coated with powder by the powder coating machine. The second slurry is introduced into the submersible coating machine and coated onto the surface of the powder-coated material. (5) Pre-frying, quick-freezing, and packaging: The material processed in step (4) is pre-fried at 190°C for 20-30 seconds, then rapidly frozen at -32°C to a core temperature of -18°C or below, and then packaged. In step (1), the natural starch that is gelatinized accounts for 40%-60% of the total natural starch; the modified starch that is gelatinized accounts for 40%-60% of the total modified starch.

2. The method for preparing fried double-skin milk pudding suitable for industrial mechanized production according to claim 1, characterized in that, The natural starch is one or more of corn starch, tapioca starch, and potato starch.

3. The method for preparing fried double-skin milk pudding suitable for industrial mechanized production according to claim 1, characterized in that, The modified starch is one or more of the following: physically modified starch, chemically modified starch, enzymatically modified starch, and compound modified starch.

4. The method for preparing fried double-skin milk pudding suitable for industrial mechanized production according to claim 1, characterized in that, The edible gum is one or more of agar, xanthan gum, gelatin, carrageenan, and guar gum.

5. The method for preparing fried double-skin milk pudding according to claim 4, characterized in that, The coating composition in step (4) is as follows: 50-70 parts high-gluten flour, 20-30 parts natural starch, 0.5-1.5 parts baking soda, 0.5-1.5 parts sodium pyrophosphate, and 0.1-1 parts spices; the parts are by weight.

6. The method for preparing fried double-skin milk pudding according to claim 5, characterized in that, In the coating composition, the natural starch is selected from one or more of the following: corn starch, tapioca starch, and potato starch; And / or, in the coating powder composition, the spices are selected from one or two of white pepper powder and garlic powder.

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