Double-layer anti-melting ice cream and processing technology thereof

Abstract

The present application relates to the technical field of ice cream, in particular to a double-layer anti-melting ice cream and a processing technology thereof; the double-layer anti-melting ice cream is composed of the following components in percentage by mass: 53.7-64.9% whole milk, 12-15% light cream, 8-10% white granulated sugar, 4-6% egg yolk liquid, 3-5% skimmed milk powder, 0.1-0.3% natural vanilla extract and 8-10% triple-state milk composition; the present application systematically solves the technical problem that the conventional ice cream collapses rapidly at room temperature and cannot maintain the plasticizing ability, realizes that the first drop time of the ice cream is prolonged by more than 4 times at 25 DEG C and the ice cream still maintains the plasticizing ability in a gel state after melting, and at the same time, the ice cream is endowed with three-stage progressive taste of clean and sweet cool feeling, explosive milk flavor and elastic chewiness, thereby providing a new solution for the ice cream industry, which has clean label, excellent anti-melting performance and unique multi-level taste.

Description

Technical Field

[0001] This invention relates to the field of ice cream technology, specifically to a double-layer anti-melting ice cream and its processing technology. Background Technology

[0002] Ice cream is a widely consumed frozen dessert. Traditional ice cream melts rapidly at room temperature, collapsing from a solid to a liquid state within minutes, and cannot maintain its shape, seriously affecting the consumer experience. Existing anti-melting technologies rely on exogenous colloids and synthetic stabilizers, such as thickeners like guar gum and sodium carboxymethyl cellulose, which delay melting by increasing the viscosity of the system. However, these additives appear as industrial additives on the ingredient list, which contradicts the current trend of clean label consumption. Moreover, excessive addition will lead to a sticky texture and reduced icy feel in the ice cream, failing to fundamentally solve the problem of maintaining its shape after melting.

[0003] Constructing a melt-resistant shell by remodeling the milk's own components is an important direction for achieving clean labeling of ice cream. However, existing milk protein gelation technologies rely on rennet or direct acidification to induce casein gelation. The former introduces exogenous enzymes, which adds a burden to the label, while the latter, due to the uncontrollable acidification rate, easily leads to excessive protein aggregation and gel shrinkage and water loss. Although the resulting gel network does not liquefy at room temperature, it lacks the ability to hold the internal melted liquid, and the single gel structure gradually cracks and fails during repeated freeze-thaw cycles due to ice crystal coarsening. Therefore, the key to overcoming the technical barrier of achieving both clean labeling and excellent melt-resistant performance in ice cream lies in how to construct a melt-resistant shell on the outer surface of ice cream without introducing non-milk additives, integrating the triple functions of ice crystal refinement, physical skeleton support, and interface barrier, and achieving the unity of post-melt shape retention and multi-layered texture through the controllable construction of a shell-core double-layer structure.

[0004] To address the above problems, the present invention provides a solution. Summary of the Invention

[0005] The purpose of this invention is to provide a double-layer anti-melting ice cream and its processing technology, which has the characteristics of significantly delaying melting at room temperature and maintaining its shape after melting, while presenting a sweet and cool sensation at oral temperature, a gradually releasing milky aroma and a multi-layered mouthfeel with a chewy texture. To achieve the above objectives, the present invention adopts the following technical solution: A double-layer anti-melting ice cream is composed of the following ingredients by mass percentage: 53.7-64.9% whole milk, 12-15% light cream, 8-10% white sugar, 4-6% egg yolk liquid, 3-5% skim milk powder, 0.1-0.3% natural vanilla extract and 8-10% triple-state milk composition; Furthermore, the triplet milk composition comprises the following components by weight percentage: 21.992% whole milk, 54.95% skim milk, 10% micellar casein concentrate, 6% whey protein isolate, 5% anhydrous butter, 0.3% milk fat stearin, 0.4% glucono-δ-lactone, 0.008% α-lactose monohydrate, and 1.35% purified water; Furthermore, the preparation method of the triplet emulsion composition includes the following steps: A1: Place skim milk in a vacuum concentration vessel, set the jacket temperature to 48-52℃ and the vacuum degree to -0.092 to -0.095MPa, and concentrate until the milk solids content reaches 35-38%. During the concentration process, control the temperature not to exceed 45℃. Collect the distilled whey and collect the concentrated product in the vacuum concentration vessel to obtain concentrated skim milk. Take α-lactose monohydrate and dry it in a vacuum drying oven at 70℃ and -0.09MPa for 6 hours. Then send it to an air jet mill, set the pulverizing pressure to 0.8MPa and the classifier speed to 8000-10000rpm to obtain ultrafine pulverized lactose powder. Seal it to prevent moisture and store it for later use. A2: Transfer the concentrated skim milk to a programmable cooling tank and cool it to 2°C at a rate of 0.4-0.6°C / min. After cooling, let it stand for 10-14 hours. Then turn on the stirrer and set the stirrer speed to 180-220 rpm. Add the ultrafine pulverized lactose powder, set the stirring temperature to 2°C, and the stirring time to 50-70 minutes to obtain the lactose nucleus guiding paste. Keep it warm at 2°C for later use. A3: Preheat whole milk to 40-45℃. Add micellar casein concentrate while stirring at 300-400 rpm, and stir for 5-8 minutes. After stirring, add whey protein isolate and continue stirring for 20-30 minutes to obtain a high-protein emulsion. Heat the high-protein emulsion to 62-68℃ and send it to a microfluidic homogenizer. Set the homogenization pressure to 180-220 MPa and perform three cycles of homogenization. During homogenization, control the instantaneous temperature peak not to exceed 72℃. After homogenization, add glucono-δ-lactone to pure water and stir at 200 rpm for 5 minutes to obtain a GDL aqueous solution. Add the GDL aqueous solution to the high-protein emulsion and stir for 3-5 minutes to mix evenly. Then immediately cool it rapidly to 4℃ through a plate heat exchanger to obtain a hybrid micellar emulsion. A4: The hybrid micelle emulsion was allowed to stand at 4°C and slowly acidified to pH 5.0-5.2 to obtain a milk protein microgel network phase, which was then kept at 4°C for later use. A5: Add anhydrous butter and dairy stearin to a fat melting tank equipped with a jacketed heating and stirring device, heat to 45-48℃, set the stirring speed to 100-150 rpm, stir for 15-20 min to obtain mixed milk fat, cool the mixed milk fat to 34-36℃, set the stirring speed to 750-850 rpm, and inject the distilled whey liquid at a rate of 4-6 ml / min through a constant flow pump while stirring. After the injection is complete, continue stirring for 10-15 min to obtain a microemulsion. Transfer the microemulsion to a programmable cooling reactor and rapidly cool it to 2℃ at a rate of 2.5-3.5℃ / min to obtain the milk fat plastic micro-unit phase, and keep it at 2℃ for later use. A6: Add the lactose nucleus guiding paste, the milk protein microgel network phase, and the milk fat plastic microunit phase to a mixing tank equipped with low-speed stirring and jacket cooling. Set the jacket temperature to 2℃ and the stirring speed to 50-80 rpm. Mix for 15-20 min to obtain a triplet milk structure composition. Keep it at 2℃ and use it within 4 hours. Furthermore, a processing method for a double-layer melt-resistant ice cream includes the following steps: S1: Dry mix granulated sugar and skim milk powder at 80 rpm for 20 minutes, then add to whole milk. Heat to 50°C, add egg yolk liquid, light cream and natural vanilla extract, and continue stirring for 20 minutes to obtain a mixture. Send the mixture to a high-pressure homogenizer for two-stage homogenization. The first homogenization pressure is 15 MPa, the second homogenization pressure is 5 MPa, and the homogenization temperature is 65°C. After homogenization, pasteurize at 85°C for 30 seconds. Immediately after pasteurization, cool to 4°C and age at the same temperature for 5 hours to obtain ice cream base. S2: Pump the ice cream base into the feed inlet of the continuous freezing machine. The freezing cylinder is divided into a front section, a middle section and a final section along the axial direction. Each section is equipped with an independent temperature control jacket and an online temperature sensor. The scraper speed of the freezing cylinder is set to increase in a gradient along the axial direction. The scraper speed of the front section is 200 rpm, the scraper speed of the middle section is 300 rpm, and the scraper speed of the final section is 380 rpm. S3: Set the temperature of the front jacket of the freezing cylinder to -10℃, the temperature of the material at the front outlet to -4℃, the temperature of the middle jacket of the freezing cylinder to -16℃, the temperature of the material at the middle outlet to -7℃, the temperature of the final jacket of the freezing cylinder to -22℃, and control the final outlet material temperature of the freezing cylinder to -6℃ to -7℃. After freezing and discharge, the material enters the molding mold and is initially formed in the mold to obtain the ice cream core. The triple-state emulsion composition, which is kept at 2℃, is evenly coated on the outer surface of the ice cream core by dipping and coating. The coating thickness is 2mm, forming an outer anti-melting shell layer, and a double-layer structure ice cream semi-finished product is obtained. S4: The double-layer ice cream semi-finished product is placed into the first gradient hardening zone, the ambient temperature is set to -12℃, and it stays for 15-18 minutes. Then it is placed into the second gradient hardening zone, the ambient temperature is set to -25℃, and it stays for 10-12 minutes. Finally, it is placed into the quick-freezing tunnel, the ambient temperature is set to -40℃, and the stay time is 20 minutes. The final hardening is completed to obtain double-layer anti-melting ice cream. Furthermore, the melting point of the milk stearin is 44℃, and the iodine value is ≤5g I2 / 100g; the protein content of the micelle casein concentrate is ≥80wt%, and the calcium content is ≥2.5wt%; the protein content of the whey protein isolate is ≥90wt%, and the lactose content is ≤1wt%. In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are as follows: 1. This invention provides a refreshing sweetness through the ice cream core and achieves a dual anti-melting function of physical support and delayed melting through the outer shell of the triple-state emulsion composition. In the triple-state emulsion composition, lactose crystal nuclei guide the paste to refine the ice crystal size of the shell layer through high-density lactose microcrystal nuclei. The milk protein microgel network phase forms a three-dimensional continuous physical skeleton at room temperature to support the melting slurry. The milk fat plastic micro-unit phase uses the solid milk fat particle interface shell as an interface barrier to block the migration of the aqueous phase. This systematically solves the key problem of traditional ice cream melting and collapsing rapidly at room temperature and failing to maintain its shape. 2: This invention uses a microgel network of milk protein induced by gluconate-δ-lactone slow-release acidification as the core framework construction mechanism, replacing the traditional ice cream's reliance on exogenous colloids and synthetic stabilizers. All components are derived from the natural components of dairy products themselves. Casein micelles form a thixotropic microgel network near the isoelectric point. Microfluidic homogenization promotes the formation of hybrid micelles of casein and whey protein, enhancing the network cross-linking density. Milk fat stearin preferentially crystallizes at the oil-water interface to form a solid particle interface stabilizing layer, which imparts physical stability to the plastic micro-unit phase of milk fat, thus balancing the contradictory requirements of melt resistance and clean labeling. 3. This invention achieves controllable manufacturing of a shell-core double-layer structure through the synergistic combination of outer layer coating and gradient hardening. The outer triple-state emulsion composition does not liquefy at room temperature and is viscoelastic. After melting, it holds the inner core in a gel state instead of brittlely breaking, giving the product a unique sweet and cool sensation, bursting milky aroma, and a chewy texture that progresses through three stages of taste. The chewy texture is not found in conventional ice cream or chocolate-coated ice cream. The distilled whey produced during the preparation of the triple-state emulsion composition is used as the inner aqueous phase raw material of the milk fat plastic micro-unit phase, realizing the closed-loop utilization of all components. This provides the ice cream industry with a new solution that combines clean labeling, excellent anti-melting performance, and a unique multi-layered taste. Detailed Implementation

[0006] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific embodiments.

[0007] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0008] Example 1 1. Take 54.95 kg of skim milk and place it in a vacuum concentration kettle. Set the jacket temperature to 48℃ and the vacuum degree to -0.092. Concentrate until the milk solids content reaches 38%. Control the temperature not to exceed 45℃ during the concentration process. Collect the distilled whey to obtain 4.2 kg of distilled whey. Collect the concentrated product in the vacuum concentration kettle to obtain 13.74 kg of concentrated skim milk. Take 8 g of α-lactose monohydrate and dry it in a vacuum drying oven at 70℃ and -0.09 MPa for 6 h. Then send it to an air jet mill and set the milling pressure to 0.8 MPa and the classifier speed to 8000 rpm to obtain 7.8 g of ultrafine pulverized lactose powder. Seal it to prevent moisture and store it for later use. 2: Transfer the concentrated skim milk to a programmable cooling tank and cool it to 2°C at a rate of 0.4°C / min. After cooling, let it stand for 10 hours. Then turn on the stirrer, set the stirrer speed to 180 rpm, add the ultrafine pulverized lactose powder, set the stirring temperature to 2°C, and the stirring time to 50 min to obtain 13.73 kg of lactose nucleus guiding paste. Keep it warm at 2°C for later use. 3: Take 21.922 kg of whole milk and preheat it to 40°C. Add 10 kg of micellar casein concentrate while stirring at 300 rpm. Stir for 5 min. After stirring, add 6 kg of whey protein isolate and continue stirring for 20 min to obtain 37.95 kg of high-protein emulsion. Heat the high-protein emulsion to 62°C and send it to a microfluidic homogenizer. Set the homogenization pressure to 180 MPa and perform 3 cycles of homogenization. During homogenization, control the instantaneous temperature peak not to exceed 72°C. After homogenization, add 0.4 kg of glucono-δ-lactone to 1.35 kg of pure water and stir at 200 rpm for 5 min to obtain 1.74 kg of GDL aqueous solution. Add the GDL aqueous solution to the high-protein emulsion and stir for 3 min to mix evenly. Then immediately cool it to 4°C through a plate heat exchanger to obtain 39.67 kg of hybrid micellar emulsion. 4: The hybrid micelle emulsion was allowed to stand at 4℃ and slowly acidified to pH 5.0 to obtain 39.62 kg of milk protein microgel network phase, which was then kept at 4℃ for later use. 5: Add 5 kg of anhydrous butter and 0.3 kg of milk stearin to a fat melting tank equipped with a jacketed heating and stirring device. Heat to 45°C, set the stirring speed to 100 rpm, and stir for 15 min to obtain 5.28 kg of mixed milk fat. Cool the mixed milk fat to 34°C, set the stirring speed to 750 rpm, and inject the distilled whey liquid at a rate of 4 ml / min through a constant flow pump while stirring. After the injection is complete, continue stirring for 10 min to obtain a microemulsion. Transfer the microemulsion to a programmable cooling reactor and rapidly cool it to 2°C at a rate of 2.5°C / min to obtain 9.43 kg of milk fat plastic micro-unit phase. Keep it warm at 2°C for later use. 6: Add the lactose nucleus guiding paste, the milk protein microgel network phase, and the milk fat plastic microunit phase to a mixing tank equipped with low-speed stirring and jacket cooling. Set the jacket temperature to 2°C and the stirring speed to 50-80 rpm. Mix for 15-20 min to obtain 62.68 kg of the triplet milk structure composition prepared in Example 1. Keep it at 2°C and use it within 4 h.

[0009] Example 2 1. Take 54.95 kg of skim milk and place it in a vacuum concentration vessel. Set the jacket temperature to 52℃ and the vacuum degree to -0.095 MPa. Concentrate until the milk solids content reaches 35%. Control the temperature not to exceed 45℃ during the concentration process. Collect the distilled whey to obtain 3.78 kg of distilled whey. Collect the concentrated product in the vacuum concentration vessel to obtain 14.12 kg of concentrated skim milk. Take 8 g of α-lactose monohydrate and dry it in a vacuum drying oven at 70℃ and -0.09 MPa for 6 hours. Then send it to an air jet mill and set the milling pressure to 0.8 MPa and the classifier speed to 10000 rpm to obtain 7.6 g of ultrafine pulverized lactose powder. Seal it to prevent moisture and store it for later use. 2: Transfer the concentrated skim milk to a programmable cooling tank and cool it to 2°C at a rate of 0.6°C / min. After cooling, let it stand for 14 hours. Then turn on the stirrer, set the stirrer speed to 220 rpm, add the ultrafine pulverized lactose powder, set the stirring temperature to 2°C, and the stirring time to 70 min to obtain 14.11 kg of lactose nucleus guiding paste. Keep it warm at 2°C for later use. 3: Take 21.922 kg of whole milk and preheat it to 45°C. Add 10 kg of micellar casein concentrate while stirring at 400 rpm. Stir for 8 minutes. After stirring, add 6 kg of whey protein isolate and continue stirring for 30 minutes to obtain 37.94 kg of high-protein emulsion. Heat the high-protein emulsion to 68°C and send it to a microfluidic homogenizer. Set the homogenization pressure to 220 MPa and perform three cycles of homogenization. During homogenization, control the instantaneous temperature peak not to exceed 72°C. After homogenization, add 0.4 kg of glucono-δ-lactone to 1.35 kg of pure water and stir at 200 rpm for 5 minutes to obtain 1.74 kg of GDL aqueous solution. Add the GDL aqueous solution to the high-protein emulsion and stir for 5 minutes to mix evenly. Then immediately cool it rapidly to 4°C through a plate heat exchanger to obtain 39.66 kg of hybrid micellar emulsion. 4: The hybrid micelle emulsion was allowed to stand at 4℃ and slowly acidified to pH 5.2 to obtain 39.61 kg of milk protein microgel network phase, which was then kept at 4℃ for later use. 5: Add 5 kg of anhydrous butter and 0.3 kg of milk stearin to a fat melting tank equipped with a jacketed heating and stirring device. Heat to 48°C, set the stirring speed to 150 rpm, and stir for 20 min to obtain 5.27 kg of mixed milk fat. Cool the mixed milk fat to 36°C, set the stirring speed to 850 rpm, and inject the distilled whey liquid at a rate of 6 ml / min through a constant flow pump while stirring. After the injection is complete, continue stirring for 15 min to obtain a microemulsion. Transfer the microemulsion to a programmable cooling reactor and quench it to 2°C at a rate of 3.5°C / min to obtain 9 kg of milk fat plastic micro-unit phase. Keep it warm at 2°C for later use. 6: Add the lactose nucleus guiding paste, the milk protein microgel network phase, and the milk fat plastic microunit phase to a mixing tank equipped with low-speed stirring and jacket cooling. Set the jacket temperature to 2°C and the stirring speed to 80 rpm. Mix for 20 min to obtain 62.62 kg of the triplet milk structure composition prepared in Example 2. Keep it at 2°C and use it within 4 h.

[0010] Example 3 1. Mix 8kg of white sugar and 3kg of skim milk powder at 80rpm for 20min, then add to 64.9kg of whole milk. Heat to 50℃, add 4kg of egg yolk liquid, 12kg of light cream and 100g of natural vanilla extract, and continue stirring for 20min to obtain a mixture. Send the mixture to a high-pressure homogenizer for two-stage homogenization. The first homogenization pressure is 15MPa, the second homogenization pressure is 5MPa, and the homogenization temperature is 65℃. After homogenization, pasteurize at 85℃ for 30s. Immediately after pasteurization, cool to 4℃ and age at the same temperature for 5h to obtain 91.8kg of ice cream base. 2: Pump the ice cream base into the feed inlet of the continuous freezing machine. The freezing cylinder is divided into a front section, a middle section and a final section along the axial direction. Each section is equipped with an independent temperature control jacket and an online temperature sensor. The scraper speed of the freezing cylinder is set to increase in a gradient along the axial direction. The scraper speed of the front section is 200 rpm, the scraper speed of the middle section is 300 rpm and the scraper speed of the final section is 380 rpm. 3: The temperature of the front jacket of the freezing cylinder is set to -10℃, the temperature of the material at the front outlet is -4℃, the temperature of the middle jacket of the freezing cylinder is -16℃, the temperature of the material at the middle outlet is -7℃, the temperature of the last jacket of the freezing cylinder is -22℃, and the final outlet temperature of the material is controlled between -6℃ and -7℃. After freezing and discharge, the material enters the molding mold and is initially formed in the mold to obtain the ice cream core. 8kg of the triple-state emulsion composition prepared in Example 1 and kept at 2℃ is evenly coated on the outer surface of the ice cream core by dipping, with a coating thickness of 2mm, forming an outer anti-melting shell layer, and 99.15kg of double-layer structure ice cream semi-finished product is obtained. 4: The double-layer ice cream semi-finished product is placed into the first gradient hardening zone, the ambient temperature is set to -12℃, and it stays for 15-18 minutes. Then it is placed into the second gradient hardening zone, the ambient temperature is set to -25℃, and it stays for 10-12 minutes. Finally, it is placed into the quick-freezing tunnel, the ambient temperature is set to -40℃, and the stay time is 20 minutes. After the final hardening is completed, 99.05 kg of the double-layer anti-melt ice cream prepared in Example 3 is obtained.

[0011] Example 4 1. Mix 10kg of granulated sugar and 5kg of skim milk powder at 80rpm for 20min, then add to 53.7kg of whole milk. Heat to 50℃, add 6kg of egg yolk liquid, 15kg of light cream and 300g of natural vanilla extract, and continue stirring for 20min to obtain a mixture. Send the mixture to a high-pressure homogenizer for two-stage homogenization. The first homogenization pressure is 15MPa, the second homogenization pressure is 5MPa, and the homogenization temperature is 65℃. After homogenization, pasteurize at 85℃ for 30s. Immediately after pasteurization, cool to 4℃ and age at the same temperature for 5h to obtain 89.8kg of ice cream base. 2: Pump the ice cream base into the feed inlet of the continuous freezing machine. The freezing cylinder is divided into a front section, a middle section and a final section along the axial direction. Each section is equipped with an independent temperature control jacket and an online temperature sensor. The scraper speed of the freezing cylinder is set to increase in a gradient along the axial direction. The scraper speed of the front section is 200 rpm, the scraper speed of the middle section is 300 rpm and the scraper speed of the final section is 380 rpm. 3: The temperature of the front jacket of the freezing cylinder is set to -10℃, the temperature of the material at the front outlet is -4℃, the temperature of the middle jacket of the freezing cylinder is -16℃, the temperature of the material at the middle outlet is -7℃, the temperature of the last jacket of the freezing cylinder is -22℃, and the final outlet temperature of the material is controlled between -6℃ and -7℃. After freezing and discharge, the material enters the molding mold and is initially formed in the mold to obtain the ice cream core. 10kg of the triple-state emulsion composition prepared in Example 2 and kept at 2℃ is evenly coated on the outer surface of the ice cream core by dipping, with a coating thickness of 2mm, forming an outer anti-melting shell layer, and 99.15kg of double-layer structure ice cream semi-finished product is obtained. 4: The double-layer ice cream semi-finished product is placed into the first gradient hardening zone, the ambient temperature is set to -12℃, and it stays for 15-18 minutes. Then it is placed into the second gradient hardening zone, the ambient temperature is set to -25℃, and it stays for 10-12 minutes. Finally, it is placed into the quick-freezing tunnel, the ambient temperature is set to -40℃, and the stay time is 20 minutes. After the final hardening is completed, 98.96 kg of the double-layer anti-melt ice cream prepared in Example 4 is obtained.

[0012] Comparative Example 1 The difference between this comparative example and Example 3 is that the outer layer of the triplet emulsion composition is not coated, that is, only a single-layer structure ice cream is prepared without a double-layer anti-melting shell. The specific preparation method is as follows: 1. Mix 8 kg of granulated sugar and 3 kg of skim milk powder at 80 rpm for 20 minutes, then add to 64.9 kg of whole milk. Heat to 50°C, add 4 kg of egg yolk liquid, 12 kg of light cream and 0.1 kg of natural vanilla extract, and continue stirring for 20 minutes to obtain 91.96 kg of mixture. Send the mixture to a high-pressure homogenizer for two-stage homogenization. The first homogenization pressure is 15 MPa, the second homogenization pressure is 5 MPa, and the homogenization temperature is 65°C. After homogenization, pasteurize at 85°C for 30 seconds. Immediately after pasteurization, cool to 4°C and age at the same temperature for 5 hours to obtain 91.80 kg of ice cream base. 2: Pump 91.80 kg of ice cream base into the feed inlet of the continuous freezing machine. The freezing cylinder is divided into a front section, a middle section and a final section along the axial direction. Each section is equipped with an independent temperature control jacket and an online temperature sensor. The scraper speed of the freezing cylinder is set to increase in a gradient along the axial direction. The scraper speed of the front section is 200 rpm, the scraper speed of the middle section is 300 rpm and the scraper speed of the final section is 380 rpm. 3: Set the temperature of the front jacket of the freezing cylinder to -10℃, the temperature of the material at the front outlet to -4℃, the temperature of the middle jacket of the freezing cylinder to -16℃, the temperature of the material at the middle outlet to -7℃, the temperature of the last jacket of the freezing cylinder to -22℃, and control the final outlet material temperature of the freezing cylinder to -6℃ to -7℃. After freezing and discharge, the material enters the molding mold and is formed in the mold to obtain 91.20kg of ice cream core. 4: The ice cream core was placed in the first gradient hardening zone, the ambient temperature was set to -12℃, and it was left for 16 minutes. Then it was placed in the second gradient hardening zone, the ambient temperature was set to -25℃, and it was left for 11 minutes. Finally, it was placed in the quick-freezing tunnel, the ambient temperature was set to -40℃, and the time was 20 minutes. After the final hardening was completed, 91.10 kg of ice cream prepared in Comparative Example 1 was obtained.

[0013] Comparative Example 2 The difference between this comparative example and Example 3 is that the outer coating material does not use the triplet emulsion composition prepared in Example 1, but instead uses an equal mass of conventional chocolate coating paste. The conventional chocolate coating paste is prepared by cocoa butter, sucrose and whole milk powder in a mass ratio of 35:45:20, with a solid content of 65%, and does not contain lactose nucleus guiding paste, milk protein microgel network phase and milk fat plastic microunit phase. The specific preparation method is as follows: 1. Mix 8 kg of granulated sugar and 3 kg of skim milk powder at 80 rpm for 20 minutes, then add to 64.9 kg of whole milk. Heat to 50°C, add 4 kg of egg yolk liquid, 12 kg of light cream and 0.1 kg of natural vanilla extract, and continue stirring for 20 minutes to obtain 91.96 kg of mixture. Send the mixture to a high-pressure homogenizer for two-stage homogenization. The first homogenization pressure is 15 MPa, the second homogenization pressure is 5 MPa, and the homogenization temperature is 65°C. After homogenization, pasteurize at 85°C for 30 seconds. Immediately after pasteurization, cool to 4°C and age at the same temperature for 5 hours to obtain 91.80 kg of ice cream base. 2: Pump 91.80 kg of ice cream base into the feed inlet of the continuous freezing machine. The freezing cylinder is divided into a front section, a middle section and a final section along the axial direction. Each section is equipped with an independent temperature control jacket and an online temperature sensor. The scraper speed of the freezing cylinder is set to increase in a gradient along the axial direction. The scraper speed of the front section is 200 rpm, the scraper speed of the middle section is 300 rpm and the scraper speed of the final section is 380 rpm. 3: Set the temperature of the front jacket of the freezing cylinder to -10℃, the material temperature at the front outlet to -4℃, the temperature of the middle jacket of the freezing cylinder to -16℃, the material temperature at the middle outlet to -7℃, the temperature of the last jacket of the freezing cylinder to -22℃, and control the final outlet material temperature of the freezing cylinder between -6℃ and -7℃. After freezing and discharge, the material enters the molding mold and is initially shaped in the mold to obtain 91.20kg of ice cream core. Add 2.8kg of cocoa butter, 3.6kg of sucrose and 1.6kg of whole milk powder to a melting tank equipped with a jacketed heating and stirring device, heat to 50℃, set the stirring speed to 200rpm, and stir for 15 minutes until completely melted and mixed evenly. Cool down to 32℃ to obtain 7.95kg of conventional chocolate coating paste. Coat 8kg of conventional chocolate coating paste evenly on the outer surface of the ice cream core by dipping, with a coating thickness of 2mm, to obtain 99.15kg of double-layer structure ice cream semi-finished product. 4: The double-layer ice cream semi-finished product was placed into the first gradient hardening zone, with an ambient temperature of -12℃ and a holding time of 16 minutes. Then it was placed into the second gradient hardening zone, with an ambient temperature of -25℃ and a holding time of 11 minutes. Finally, it was placed into the quick-freezing tunnel, with an ambient temperature of -40℃ and a holding time of 20 minutes. After the final hardening was completed, 99.05 kg of the double-layer chocolate crispy ice cream prepared in Comparative Example 2 was obtained.

[0014] Room temperature melt resistance test Ice cream samples prepared in Examples 3, 4, Comparative Example 1, and Comparative Example 2 were placed in a constant temperature environment of 25℃±1℃. The initial temperature of the samples was -18℃. The time from when the samples were taken out to when the first obvious melt drop appeared (first drop time) was recorded, as well as the shape retention rate after being placed at 25℃ for 60 minutes (based on the initial height of the sample, the percentage of the remaining height after 60 minutes was measured to the initial height). At the same time, the morphological changes during the melting process were observed and recorded. Each group of samples was tested in parallel 3 times, and the average value was taken and the test results were recorded. Table 1. Results of room temperature melt resistance test ; As shown in Table 1, the first drop time of Examples 3 and 4 reached 42.5 min and 38.7 min respectively, which were extended by 419% and 372% compared with Comparative Example 1. The shape retention rate at 60 min was maintained at 68.3% and 72.5% respectively, proving that the outer anti-melting shell formed by the triplet emulsion composition can effectively delay internal melting and maintain the overall plasticity at room temperature. The shape retention rate of Example 4 is higher than that of Example 3. The reason is that the amount of the outer triple emulsion composition in Example 4 is 10%, the shell is thicker, and the holding capacity is stronger. Comparative Example 1 has no double-layer structure, the first drop time is only 8.2 minutes, and it completely collapses in 12 minutes. This shows that the single-structure ice cream has no physical framework support after melting at room temperature, and the system quickly disintegrates into a liquid state after the ice crystals melt. Comparative Example 2 had an initial drop time of 15.6 min, which was longer than that of Comparative Example 1. However, the chocolate shell cracked after 22 min and lost its barrier function. The internal slurry flowed out, causing the shape retention rate to drop to zero. This proves that conventional chocolate shells do not have a viscoelastic skeleton holding function at room temperature and cannot be compared with the physical network effect of the milk protein microgel network phase of the triplet milk structure composition.

[0015] Sensory evaluation of progressive taste levels Twenty trained sensory evaluators were selected to evaluate the progressive taste levels of ice cream samples prepared in Example 3, Example 4, Comparative Example 1, and Comparative Example 2 using a blind evaluation method. The sample temperature was -18℃. The evaluation indicators included: initial coolness (1-5 points), mid-chewing milk flavor release intensity (1-5 points), late-chewing chewiness (1-5 points), and richness of taste levels (1-5 points). The higher the score, the stronger the sensory characteristic. The scores were recorded and the average value was taken. Table 2. Sensory evaluation results of the progressive taste levels ; Analysis of Table 2 shows that Examples 3 and 4 are comparable to Comparative Examples 1 and 2 in terms of initial cooling sensation, indicating that the outer shell does not affect the initial cooling release of the ice cream core. In terms of mid-term milk aroma release intensity, Examples 3 and 4 reached 4.3 and 4.6 points respectively, which are significantly higher than the 3.2 points of Comparative Example 1. The reason for this is that the milk fat plastic micro-unit phase in the outer triple-state milk structure composition breaks down during oral chewing, and the concentrated whey and milk fat are released simultaneously, forming a burst of milk aroma. In terms of the chewy texture in the later stage, Examples 3 and 4 scored 4.6 and 4.8 points respectively, while Comparative Example 1 scored only 1.2 points, with almost no chewiness, and Comparative Example 2 scored only 1.8 points. This proves that the milk protein microgel network phase changes from a brittle state to a flexible state at oral temperature, providing a chewy texture similar to milk skin, which is not available in conventional ice cream and chocolate-coated ice cream. Example 4 has the richest texture, with a thicker shell and higher milk fat content, resulting in a fuller milk aroma and chewy texture.

[0016] Freeze-thaw cycle stability test Ice cream samples prepared in Examples 3, 4, Comparative Example 1, and Comparative Example 2 were subjected to three freeze-thaw cycles (each cycle consisted of taking the samples out of -25°C, placing them in a 25°C environment for 30 minutes, and then returning them to -25°C to freeze for 6 hours). After each cycle, the integrity of the sample appearance was observed and the mass loss rate was measured. The appearance changes and cumulative mass loss rate after the third cycle were recorded. Each group of samples was tested in parallel three times, and the average value was taken and the test results were recorded. Table 3. Results of freeze-thaw cycle stability test ; Analysis of Table 3 shows that after three freeze-thaw cycles, the cumulative mass loss rates of Examples 3 and 4 were only 4.2% and 3.5%, respectively, and the outer shells remained largely intact. This demonstrates that the lactose nuclei in the shell of the triplet milk composition guided the paste to refine the ice crystals inside the shell, and the milk protein microgel network phase provided an elastic framework, which could buffer the stress caused by the volume change of ice crystals during repeated freeze-thaw cycles and prevent the shell from cracking. The mass loss rate of Example 4 was lower than that of Example 3, which is attributed to the fact that the shell of Example 4 was thicker and had stronger resistance to freeze-thaw damage. Comparative Example 1 had no outer protective layer. After three freeze-thaw cycles, repeated recrystallization of ice crystals led to the complete disintegration of the system, with a mass loss rate as high as 18.6%. In Comparative Example 2, the chocolate coating cracked due to the difference in thermal expansion coefficients between the coating and the core during the freeze-thaw process. After a large area of ​​the coating peeled off, the core was directly exposed, the ice crystals became coarser, and the mass loss rate reached 11.8%. This indicates that conventional chocolate coatings cannot adapt to the dimensional changes caused by repeated freeze-thaw cycles.

[0017] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A double-layer anti-melting ice cream, characterized in that, It consists of the following ingredients by weight percentage: 53.7-64.9% whole milk, 12-15% heavy cream, 8-10% white sugar, 4-6% egg yolk liquid, 3-5% skim milk powder, 0.1-0.3% natural vanilla extract and 8-10% triplet milk composition.

2. The double-layer anti-melting ice cream according to claim 1, characterized in that, The triplet milk composition comprises the following components by weight percentage: 21.992% whole milk, 54.95% skim milk, 10% micellar casein concentrate, 6% whey protein isolate, 5% anhydrous butter, 0.3% milk fat stearin, 0.4% glucono-δ-lactone, 0.008% α-lactose monohydrate, and 1.35% purified water.

3. The double-layer anti-melting ice cream according to claim 1, characterized in that, The preparation method of the triplet emulsion composition includes the following steps: A1: Place skim milk in a vacuum concentration vessel, set the jacket temperature to 48-52℃ and the vacuum degree to -0.092 to -0.095MPa, and concentrate until the milk solids content reaches 35-38%. During the concentration process, control the temperature not to exceed 45℃. Collect the distilled whey and collect the concentrated product in the vacuum concentration vessel to obtain concentrated skim milk. Take α-lactose monohydrate and dry it in a vacuum drying oven at 70℃ and -0.09MPa for 6 hours. Then send it to an air jet mill, set the pulverizing pressure to 0.8MPa and the classifier speed to 8000-10000rpm to obtain ultrafine pulverized lactose powder. Seal it to prevent moisture and store it for later use. A2: Transfer the concentrated skim milk to a programmable cooling tank and cool it to 2°C at a rate of 0.4-0.6°C / min. After cooling, let it stand for 10-14 hours. Then turn on the stirrer and set the stirrer speed to 180-220 rpm. Add the ultrafine pulverized lactose powder, set the stirring temperature to 2°C, and the stirring time to 50-70 minutes to obtain the lactose nucleus guiding paste. Keep it warm at 2°C for later use. A3: Preheat whole milk to 40-45℃. Add micellar casein concentrate while stirring at 300-400 rpm, and stir for 5-8 minutes. After stirring, add whey protein isolate and continue stirring for 20-30 minutes to obtain a high-protein emulsion. Heat the high-protein emulsion to 62-68℃ and send it to a microfluidic homogenizer. Set the homogenization pressure to 180-220 MPa and perform three cycles of homogenization. During homogenization, control the instantaneous temperature peak not to exceed 72℃. After homogenization, add glucono-δ-lactone to pure water and stir at 200 rpm for 5 minutes to obtain a GDL aqueous solution. Add the GDL aqueous solution to the high-protein emulsion and stir for 3-5 minutes to mix evenly. Then immediately cool it rapidly to 4℃ through a plate heat exchanger to obtain a hybrid micellar emulsion. A4: The hybrid micelle emulsion was allowed to stand at 4°C and slowly acidified to pH 5.0-5.2 to obtain a milk protein microgel network phase, which was then kept at 4°C for later use. A5: Add anhydrous butter and dairy stearin to a fat melting tank equipped with a jacketed heating and stirring device, heat to 45-48℃, set the stirring speed to 100-150 rpm, stir for 15-20 min to obtain mixed milk fat, cool the mixed milk fat to 34-36℃, set the stirring speed to 750-850 rpm, and inject the distilled whey liquid at a rate of 4-6 ml / min through a constant flow pump while stirring. After the injection is complete, continue stirring for 10-15 min to obtain a microemulsion. Transfer the microemulsion to a programmable cooling reactor and rapidly cool it to 2℃ at a rate of 2.5-3.5℃ / min to obtain the milk fat plastic micro-unit phase, and keep it at 2℃ for later use. A6: Add the lactose nucleus guiding paste, the milk protein microgel network phase, and the milk fat plastic microunit phase to a mixing tank equipped with low-speed stirring and jacket cooling. Set the jacket temperature to 2℃ and the stirring speed to 50-80 rpm. Mix for 15-20 min to obtain a triplet milk structure composition. Keep it at 2℃ and use it within 4 hours.

4. The double-layer anti-melting ice cream according to claim 1, characterized in that, The melt stearin has a melting point of 44℃ and an iodine value of ≤5g I2 / 100g.

5. A double-layer anti-melting ice cream according to claim 1, characterized in that, The micelle casein concentrate has a protein content of ≥80wt% and a calcium content of ≥2.5wt%.

6. The double-layer anti-melting ice cream according to claim 1, characterized in that, The whey protein isolate has a protein content of ≥90wt% and a lactose content of ≤1wt%.

7. The processing technology for a double-layer anti-melting ice cream according to claim 1, characterized in that, Includes the following steps: S1: Dry mix granulated sugar and skim milk powder at 80 rpm for 20 minutes, then add to whole milk. Heat to 50°C, add egg yolk liquid, light cream and natural vanilla extract, and continue stirring for 20 minutes to obtain a mixture. Send the mixture to a high-pressure homogenizer for two-stage homogenization. The first homogenization pressure is 15 MPa, the second homogenization pressure is 5 MPa, and the homogenization temperature is 65°C. After homogenization, pasteurize at 85°C for 30 seconds. Immediately after pasteurization, cool to 4°C and age at the same temperature for 5 hours to obtain ice cream base. S2: Pump the ice cream base into the feed inlet of the continuous freezing machine. The freezing cylinder is divided into a front section, a middle section and a final section along the axial direction. Each section is equipped with an independent temperature control jacket and an online temperature sensor. The scraper speed of the freezing cylinder is set to increase in a gradient along the axial direction. The scraper speed of the front section is 200 rpm, the scraper speed of the middle section is 300 rpm, and the scraper speed of the final section is 380 rpm. S3: Set the temperature of the front jacket of the freezing cylinder to -10℃, the temperature of the material at the front outlet to -4℃, the temperature of the middle jacket of the freezing cylinder to -16℃, the temperature of the material at the middle outlet to -7℃, the temperature of the final jacket of the freezing cylinder to -22℃, and control the final outlet material temperature of the freezing cylinder to -6℃ to -7℃. After freezing and discharge, the material enters the molding mold and is initially formed in the mold to obtain the ice cream core. The triple-state emulsion composition, which is kept at 2℃, is evenly coated on the outer surface of the ice cream core by dipping and coating. The coating thickness is 2mm, forming an outer anti-melting shell layer, and a double-layer structure ice cream semi-finished product is obtained. S4: The double-layer ice cream semi-finished product is placed into the first gradient hardening zone, the ambient temperature is set to -12℃, and it stays for 15-18 minutes. Then it is placed into the second gradient hardening zone, the ambient temperature is set to -25℃, and it stays for 10-12 minutes. Finally, it is placed into the quick-freezing tunnel, the ambient temperature is set to -40℃, and the stay time is 20 minutes. The final hardening is completed to obtain double-layer anti-melt ice cream.