Flow-center wiredrawing cheese snack with multi-layer composite structure and preparation method of flow-center wiredrawing cheese snack

Abstract

The invention discloses a flowing-center wiredrawing cheese snack with a multi-layer composite structure and a preparation method of the flowing-center wiredrawing cheese snack, and belongs to the technical field of food processing. The snack is formed by sequentially compounding an outer cheese layer, a middle wiredrawing glutinous rice skin layer and an inner flowing core cheese layer from outside to inside, wherein the water activity (Aw) of the three-layer structure is accurately regulated and controlled to be in a gradient relation (0.65-0.70-0.75-0.80-0.85) which is sequentially increased from outside to inside. Through cooperation of the gradient structure, a specific formula and a key process, moisture migration and texture deterioration of the product in the storage process are effectively inhibited. According to the invention, the long-term stable storage (more than or equal to 8.5 months) of the product under the condition of 25 + / -2 DEG C is successfully realized, and multiple common technical bottlenecks of flow center solidification, wire drawing performance degradation, out-of-control moisture migration, microbial pollution and the like of the existing flow center wire drawing product in a normal-temperature environment are systematically solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of food processing, and particularly relates to a multi-layer composite structure of a flow center string cheese snack and a preparation method thereof. BACKGROUND

[0002] Cheese snacks are popular due to their rich nutrition and unique flavor. In the prior art, cheese products with flow center or string texture (such as flow center cheese tart, snow beauty, etc.) usually need to be frozen or refrigerated for storage to prevent microbial spoilage, water migration and texture collapse. This greatly limits its circulation convenience and consumption scenarios. Although some technologies attempt to develop room temperature cheese snacks, it is often difficult to simultaneously meet multiple texture requirements such as "long shelf life", "stable flow center" and "excellent stringiness". For example, simply reducing the water activity can prolong the shelf life, but it will result in a dry and hard texture and loss of flow center; while pursuing flow center stringiness will make the product water activity too high, which is not conducive to room temperature storage. In addition, during storage, water and oil migration between different texture layers can easily cause product leakage, layering and damage to the overall structure. Therefore, developing a multi-layer structure cheese snack that can be stored at room temperature while perfectly presenting the flow center and string composite texture has become a technical problem that needs to be solved in the field. SUMMARY

[0003] To solve the above technical problems, the present application provides a multi-layer composite structure of a flow center string cheese snack and a preparation method thereof. The core of the present application is that by combining "three-layer composite structure" with "water activity gradient design", the direction of water migration is synergistically controlled, and specific formula system, key process parameters and integrated stabilization packaging are used to achieve the comprehensive effect of stable product structure, rich taste and long shelf life at room temperature.

[0004] To achieve the above purpose, the present application adopts the following technical solutions:

[0005] In a first aspect, the present application provides a multi-layer composite structure of a flow center string cheese snack. The snack comprises, from outside to inside, an outer cheese layer, a middle stringy glutinous rice skin layer and an inner flow center cheese layer. The key is that the three-layer structure has a specific water activity (Aw) gradient: the water activity (Aw) of the outer cheese layer is ≤0.65, the water activity of the middle stringy glutinous rice skin layer is 0.70-0.75, and the water activity of the inner flow center cheese layer is 0.80-0.85. This Aw increasing system from outside to inside can form a directional driving force for water migration from the high-activity inner layer to the low-activity outer layer, effectively inhibiting the disordered diffusion and local accumulation of water between layers, and is the basis for the product to resist leakage and maintain the ideal texture of each layer at room temperature.

[0006] Preferably, the mass ratio of the outer cheese layer, the middle stretchy glutinous rice skin layer, and the inner flowing cheese layer is (55-65):(25-35):(8-12).

[0007] The 60:30:10 ratio described in this invention is the optimal implementation method, which can maximize the synergistic optimization of taste, structure and shelf life; other ratios within this preferred range, such as 58:32:10 or 62:28:10, can also adapt to different product design requirements while ensuring overall functionality.

[0008] Preferably, the middle stretchy glutinous rice skin layer comprises glutinous rice flour, tapioca starch, hydroxypropyl starch phosphate and glyceryl monostearate, wherein the mass ratio of glutinous rice flour to tapioca starch is (1.5-2.5):1.

[0009] Among them, the glutinous rice flour to tapioca starch ratio can achieve the stringing function in the range of (1.5-2.5):1, while the ratio of 2:1 is the best, with the stringing length, elasticity and structural support reaching the best balance. If the ratio deviates from this preferred range, for example, if it is adjusted to 1:1, the stringing performance will be significantly reduced, the texture will become harder, and the overall sensory score of the product will be reduced.

[0010] Preferably, the molten cheese filling comprises natural cheese, whey protein, edible gelatin, sugar alcohol, and emulsifier; the emulsifier includes glyceryl monostearate and / or polyglycerol fatty acid esters. This combination, through the synergistic effect of proteins and colloids, can form a semi-fluid gel structure that is stable at room temperature and has a smooth and delicate texture under preferred process parameters.

[0011] Preferably, the outer cheese layer comprises cream cheese, whole milk powder, sugar alcohols, and polyglycerol fatty acid esters. This formula, combined with a specific whipping process, can create a light, soft, and supportive foam-like cheese layer, providing the product with a good appearance and initial taste, and forming a harmonious flavor and texture transition with the middle and inner layers.

[0012] Secondly, the present invention provides a method for preparing the above-mentioned molten cheese snack, comprising the following steps:

[0013] (1) Preparation of the molten cheese filling: Natural cheese, whey protein, sugar alcohol, edible gelatin, emulsifier and water are mixed and vacuum homogenized and emulsified at 60-65℃ and 15-25 MPa pressure to obtain a molten cheese filling with a water activity (Aw) of 0.80-0.85, which is then cooled for later use. This process ensures that the protein and gelatin fully interact to form a delicate and stable molten core structure.

[0014] (2) Preparation of the middle stretchable glutinous rice skin: Glutinous rice flour, tapioca starch, hydroxypropyl starch phosphate, glyceryl monostearate and water are mixed to form a dough. After steaming and gelatinizing, the dough is kneaded at a constant temperature of 38-42℃ and pressed into a skin. The water activity (Aw) of this skin is 0.70-0.75. Constant temperature kneading helps the starch network to rearrange in an orderly manner, giving the skin excellent extensibility and stretchability.

[0015] (3) Preparation of outer cheese base: Mix cream cheese, whole milk powder, sugar alcohol, polyglycerol fatty acid ester and water, stir and whip at 45-55℃ to prepare a cheese base with water activity (Aw) ≤0.65.

[0016] (4) Composite molding and packaging: The obtained glutinous rice skin material is wrapped around the obtained molten cheese paste to form a sandwich core, and then the obtained outer cheese base material is used to wrap the sandwich core for molding; the molded product is vacuum packaged with high barrier material, and a composite desiccant is added inside the packaging, followed by pasteurization.

[0017] Preferably, the vacuum homogenization emulsification temperature is 62°C and the pressure is 20 MPa. This specific combination of temperature and pressure ensures that the whey protein is fully denatured, the edible gelatin is completely dissolved, and it is fully cross-linked with other components, thereby forming a uniform, delicate gel network with suitable viscoelasticity. If the temperature is too high (e.g., 70°C), although a gel can still be formed, it may lead to the loss of some flavor substances, excessive protein denaturation resulting in a hard texture in the liquid, and reduced flavor encapsulation. If the pressure is insufficient, the emulsification uniformity will be insufficient, which may easily lead to a grainy texture in the liquid or phase separation during storage.

[0018] Preferably, the constant-temperature kneading temperature is 40°C. Kneading at this temperature facilitates the orderly rearrangement of starch molecular chains after cooking and gelatinization under sufficient thermal energy, forming a three-dimensional network structure with excellent extensibility and moderate elasticity, thereby giving the skin excellent stringing properties and a good chewy texture. If the kneading temperature is too low, the starch chain mobility is insufficient, the network structure is not fully developed, resulting in a shortened stringing length, abnormally high elasticity but poor adhesion of the skin; if the temperature is too high, it may lead to excessive evaporation of moisture, causing the skin to dry and harden, affecting the taste.

[0019] Preferably, the high-barrier material is a PET / AL / PE composite film; the composite desiccant is a mixture of silica gel and montmorillonite. Its excellent oxygen and moisture barrier properties (e.g., oxygen permeability ≤ 5 cm³ / (m²·24h·0.1MPa)) effectively prevent the intrusion of external oxygen and moisture, preventing product oxidation and moisture absorption. Simultaneously, the silica gel and montmorillonite composite desiccant added to the packaging actively adsorbs free moisture within the packaging, dynamically regulating the humidity of the internal microenvironment, further inhibiting microbial growth and water activity fluctuations, forming a dual-protection system with the high-barrier packaging.

[0020] Preferably, the pasteurization is performed in a 60°C water bath for 15-20 minutes. This mild heat treatment is sufficient to inactivate the vast majority of spoilage and pathogenic bacteria in the product, while maximally protecting the unique flavor compounds, protein functions, and texture of each layer of cheese from damage by high temperatures.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) This invention uses three layers of textured layers with different Aw to give the product a rich texture (soft outer layer, chewy and stringy middle layer, and smooth and flowing inner layer), while using the Aw gradient to spontaneously guide the directional migration of water, thus fundamentally solving the problems of leakage and texture deterioration in multi-layered foods.

[0023] (2) The present invention achieves long-term stability of multiple ideal textures at room temperature: after the product is stored at 25°C for 9 months, it can still maintain a drawing length of ≥4.3cm, a flow rate of ≥80% and a leakage rate of ≤4%, with excellent sensory quality, breaking through the technical bottleneck of existing similar products that must be stored in a cold chain.

[0024] (3) This invention provides a new and effective approach to solving the contradiction between textural stability and taste richness in room temperature cheese snacks, and has significant technological progress and broad market potential. Attached Figure Description

[0025] Figure 1 This is an appearance drawing of the product prepared in Example 1 of the present invention. Detailed Implementation

[0026] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0027] The following examples are for illustrative purposes only and are not intended to limit the scope of the invention. All raw materials used in the preparation method are conventional raw materials used in the food industry and can be purchased through conventional market channels. To ensure process stability and final product quality, some key raw materials underwent the following pretreatment before feeding:

[0028] Natural cheese pretreatment: Place the natural cheese in a 40°C water bath to soften to a degree of softening of not less than 80%, and then pass it through an 80-mesh sieve to ensure uniform texture and remove potential impurities.

[0029] Pretreatment of powdered raw materials: Glutinous rice flour, tapioca starch, and whole milk powder are dried at 60℃ for 2 hours to ensure that their moisture content is not higher than 8%, so as to prevent the dispersion and mixing uniformity from being affected by moisture absorption and clumping during subsequent processing.

[0030] Emulsifier pretreatment: Emulsifiers such as glyceryl monostearate and polyglycerol fatty acid esters are premixed with maltitol to prepare a premix, so as to improve its dispersion efficiency and stability in subsequent emulsification and mixing processes.

[0031] Example 1: A three-layer composite molten cheese snack and its preparation

[0032] This embodiment provides a three-layer composite structure of a molten cheese snack, including an outer soft cheese layer, a middle molten mochi skin layer, and an inner molten cheese layer.

[0033] The outer soft cheese layer contains the following components by weight: 45.0 parts cream cheese (50% milk fat content), 18.0 parts whole milk powder (25% milk fat content), 15.0 parts maltitol (purity ≥99%), 3.0 parts polyglycerol fatty acid ester (food grade), and 19.0 parts deionized water;

[0034] The middle layer of the mochi skin contains the following components by weight: 35.0 parts glutinous rice flour (90% amylopectin content), 18.0 parts tapioca starch (≥98% purity), 9.0 parts cheese powder (40% milk fat content), 4.0 parts hydroxypropyl starch phosphate (food grade), 1.5 parts glyceryl monostearate (food grade), and 42.5 parts deionized water;

[0035] The inner molten cheese layer contains the following components by weight: 55.0 parts natural cheese (35% milk fat content), 6.0 parts whey protein (≥90% purity), 4.0 parts edible gelatin (Bloom 250), 1.0 part glyceryl monostearate (food grade), 2.0 parts polyglycerol fatty acid ester (food grade), 12.0 parts maltitol (≥99% purity), and 10.0 parts deionized water.

[0036] The specific preparation method is as follows:

[0037] (1) Preparation of the molten cheese filling: Softened natural cheese, whey protein, and maltitol were added to a vacuum emulsifying homogenizer and premixed for 5 minutes at 300 r / min. Then, edible gelatin, a compound emulsifier (premixed glyceryl monostearate and polyglycerol fatty acid esters), and deionized water were added. The mixture was heated to 62°C and homogenized at a vacuum of -0.09 MPa, a homogenization pressure of 20 MPa, and a rotation speed of 1500 r / min for 25 minutes. After emulsification, the material was rapidly cooled to 25°C and placed in a 4°C environment for 1 hour to set, forming a stable semi-liquid gel-like filling.

[0038] (2) Preparation of the middle stretchy mochi skin: Mix glutinous rice flour, tapioca starch, cheese powder, and hydroxypropyl starch phosphate evenly. Add deionized water and glyceryl monostearate, and stir into a smooth dough without lumps. Steam the dough in 100℃ steam for 18 minutes to ensure complete starch gelatinization (gelatinization degree ≥95%). Then, immediately transfer the steamed dough to a constant temperature kneading machine at 40℃ and knead at 50 r / min for 10 minutes. Finally, press the dough into round thin sheets with a thickness of 2.5 mm and a diameter of 5 cm for later use.

[0039] (3) Preparation of the outer soft cheese layer: Place cream cheese, whole milk powder and maltitol in a planetary mixer. At 50°C, first mix at a low speed of 200 r / min for 5 minutes to ensure even mixing. Then add polyglycerol fatty acid ester and deionized water, increase the speed to 500 r / min, and continue beating for 15 minutes. After beating, cool to 30°C and let stand for 10 minutes.

[0040] (4) Three-layer composite molding: Take 30 g of the prepared middle stretchy mochi skin, put 10 g of the shaped inner flowing cheese layer in the center, and tightly wrap it by hand or mechanical "pleating wrapping method" to form a spherical middle blank. Then, immerse the middle blank in the soft cheese layer liquid, and use "rolling wrapping method" to evenly wrap it with 60 g of soft cheese layer to form a primary product with a total weight of 100 g. Place the primary product in a constant temperature and humidity chamber at 25℃ and 50% relative humidity for 30 minutes to solidify and make the structure of each layer tightly bonded.

[0041] (5) Room temperature stabilization treatment and packaging: The cured product is vacuum-packed using a PET / AL / PE composite film (oxygen permeability ≤ 5 cm³ / (m²·24h·0.1 MPa)). Each bag contains 5 g of a composite desiccant made from a 1:1 mass ratio of silica gel and montmorillonite. The packaged product is then pasteurized in a 60°C water bath for 15 minutes. After sterilization, it is rapidly cooled to 25°C to obtain the finished product (see...). Figure 1 (See appearance diagram), can be stored at room temperature (25±2℃).

[0042] The water activity (Aw) of each layer of the product was measured using a high-precision water activity meter and met the design gradient: the Aw of the outer layer was 0.62 (≤0.65), the Aw of the middle layer was 0.73 (0.70-0.75), and the Aw of the inner layer was 0.82 (0.80-0.85).

[0043] Example 2: A three-layer composite molten cheese snack and its preparation

[0044] This embodiment provides a three-layer composite molten cheese snack, which is prepared using the same method as in Example 1. The formula is adjusted by finely modifying the amount of water added to each layer and the amount of maltitol used, as follows:

[0045] The outer soft cheese layer contains the following components by weight: 45.0 parts cream cheese (50% milk fat content), 18.0 parts whole milk powder (25% milk fat content), 18.0 parts maltitol (purity ≥99%), 3.0 parts polyglycerol fatty acid ester (food grade), and 21.0 parts deionized water;

[0046] The middle layer of the mochi skin contains the following components by weight: 35.0 parts glutinous rice flour (90% amylopectin content), 18.0 parts tapioca starch (≥98% purity), 9.0 parts cheese powder (40% milk fat content), 4.0 parts hydroxypropyl starch phosphate (food grade), 1.5 parts glyceryl monostearate (food grade), and 40.0 parts deionized water;

[0047] The inner molten cheese layer contains the following components by weight: 55.0 parts natural cheese (35% milk fat content), 6.0 parts whey protein (≥90% purity), 4.0 parts edible gelatin (Bloom 250), 1.0 part glyceryl monostearate (food grade), 2.0 parts polyglycerol fatty acid ester (food grade), 10.0 parts maltitol (99% purity), and 12.0 parts deionized water.

[0048] The product was tested using the same Aw measurement method as in Example 1, and the Aw values ​​were 0.63 for the outer layer, 0.72 for the middle layer, and 0.83 for the inner layer.

[0049] Example 3

[0050] This embodiment provides a three-layer composite molten cheese snack, which is prepared using the same method as in Example 1. The formula is adjusted by finely modifying the amount of water added to each layer and the amount of maltitol used, as follows:

[0051] The outer soft cheese layer contains the following components by weight: 45.0 parts cream cheese (50% milk fat content), 18.0 parts whole milk powder (25% milk fat content), 21.0 parts maltitol (purity ≥99%), 3.0 parts polyglycerol fatty acid ester (food grade), and 12.0 parts deionized water;

[0052] The middle layer of the mochi skin contains the following components by weight: 35.0 parts glutinous rice flour (90% amylopectin content), 18.0 parts tapioca starch (≥98% purity), 9.0 parts cheese powder (40% milk fat content), 4.0 parts hydroxypropyl starch phosphate (food grade), 1.5 parts glyceryl monostearate (food grade), and 36.0 parts deionized water;

[0053] The inner molten cheese layer contains the following components by weight: 55.0 parts natural cheese (35% milk fat content), 6.0 parts whey protein (purity ≥90%), 4.0 parts edible gelatin (Bloom 250), 1.0 part glyceryl monostearate (food grade), 2.0 parts polyglycerol fatty acid ester (food grade), 8.0 parts maltitol (purity ≥99%), and 14.0 parts deionized water.

[0054] The product was tested using the same Aw measurement method as in Example 1, and the Aw of the outer layer was 0.65, the Aw of the middle layer was 0.70, and the Aw of the inner layer was 0.85.

[0055] Example 4

[0056] This embodiment provides a three-layer composite molten cheese snack, which is prepared using the same method as in Example 1. The formula is adjusted by finely modifying the amount of water added to each layer and the amount of maltitol used, as follows:

[0057] The outer soft cheese layer contains the following components by weight: 45.0 parts cream cheese (50% milk fat content), 18.0 parts whole milk powder (25% milk fat content), 16.0 parts maltitol (purity ≥99%), 3.0 parts polyglycerol fatty acid ester (food grade), and 17.0 parts deionized water;

[0058] The middle layer of the mochi skin contains the following components by weight: 35.0 parts glutinous rice flour (90% amylopectin content), 18.0 parts tapioca starch (≥98% purity), 9.0 parts cheese powder (40% milk fat content), 4.0 parts hydroxypropyl starch phosphate (food grade), 1.5 parts glyceryl monostearate (food grade), and 44.0 parts deionized water;

[0059] The inner molten cheese layer contains the following components by weight: 55.0 parts natural cheese (35% milk fat content), 6.0 parts whey protein (purity ≥90%), 4.0 parts edible gelatin (Bloom 250), 1.0 part glyceryl monostearate (food grade), 2.0 parts polyglycerol fatty acid ester (food grade), 12.0 parts maltitol (purity ≥99%), 10.0 parts deionized water, and 5.0 parts glycerol.

[0060] The product was tested using the same Aw measurement method as in Example 1, and the Aw values ​​were 0.61 for the outer layer, 0.74 for the middle layer, and 0.84 for the inner layer.

[0061] Example 5: A three-layer composite molten cheese snack and its preparation

[0062] The only difference between this embodiment and Example 1 is the starch ratio in the middle layer of the mochi skin. The mass ratio of glutinous rice flour to tapioca starch is adjusted to 1:1. Specifically, the ratio is 26.5 parts glutinous rice flour, 26.5 parts tapioca starch, and 32.5 parts deionized water. The remaining components and their masses remain unchanged. The total mass of the product and the formulas for the outer and inner layers are exactly the same as in Example 1. The preparation method is the same as in Example 1.

[0063] The product was tested using the same Aw measurement method as in Example 1, and the Aw values ​​were 0.62 for the outer layer, 0.73 for the middle layer, and 0.82 for the inner layer.

[0064] Example 6: A three-layer composite molten cheese snack and its preparation

[0065] The only difference between this embodiment and Example 1 is that the emulsification and homogenization temperature of the inner lava cheese layer is adjusted, increasing it from 62°C in Example 1 to 70°C. All other formulations and preparation methods are the same as in Example 1.

[0066] The product was tested using the same Aw measurement method as in Example 1, and the Aw values ​​were 0.62 for the outer layer, 0.73 for the middle layer, and 0.82 for the inner layer.

[0067] Example 7: A three-layer composite molten cheese snack and its preparation

[0068] The only difference between this embodiment and Example 1 is that the constant temperature kneading temperature of the middle stretchy mochi skin layer is adjusted, reducing it from 40℃ in Example 1 to 35℃. All other formulas and preparation processes are the same as in Example 1.

[0069] The product was tested using the same Aw measurement method as in Example 1, and the Aw values ​​were 0.62 for the outer layer, 0.73 for the middle layer, and 0.82 for the inner layer.

[0070] Comparative Example 1

[0071] The difference between this comparative example and Example 1 is that the formulation was adjusted so that the water activity (Aw) of the outer, middle, and inner layers of the product is approximately 0.75. The preparation method is the same as in Example 1. The specific formulation is as follows:

[0072] The outer soft cheese layer contains the following components by weight: 45.0 parts cream cheese (50% milk fat content), 18.0 parts whole milk powder (25% milk fat content), 5.0 parts maltitol (purity ≥99%), 3.0 parts polyglycerol fatty acid ester (food grade), and 34.0 parts deionized water;

[0073] The middle layer of the mochi skin contains the following components by weight: 35.0 parts glutinous rice flour (90% amylopectin content), 18.0 parts tapioca starch (≥98% purity), 9.0 parts cheese powder (40% milk fat content), 4.0 parts hydroxypropyl starch phosphate (food grade), 1.5 parts glyceryl monostearate (food grade), and 38.5 parts deionized water;

[0074] The inner molten cheese layer contains the following components by weight: 55.0 parts natural cheese (35% milk fat content), 6.0 parts whey protein (purity ≥90%), 4.0 parts edible gelatin (Bloom 250), 1.0 part glyceryl monostearate (food grade), 2.0 parts polyglycerol fatty acid ester (food grade), 5.0 parts maltitol (purity ≥99%), and 12.0 parts deionized water.

[0075] Comparative Example 2

[0076] The product in this comparative example has a double-layer structure, with a soft cheese layer directly wrapping a molten cheese filling layer. The total weight is 100g, with the molten cheese filling layer accounting for 30% and the soft cheese layer accounting for 70%. All steps related to the intermediate layer were removed from the preparation process; the rest is the same as in Example 1. Details are as follows:

[0077] The outer soft cheese layer contains the following components by weight: 70.0 parts cream cheese (50% milk fat content), 28.0 parts whole milk powder (25% milk fat content), 23.0 parts maltitol (purity ≥99%), 4.7 parts polyglycerol fatty acid esters (food grade), and 34.3 parts deionized water;

[0078] The inner molten cheese layer contains the following components by weight: 165.0 parts natural cheese (35% milk fat content), 18.0 parts whey protein (purity ≥90%), 12.0 parts edible gelatin (Bloom 250), 3.0 parts glyceryl monostearate (food grade), 6.0 parts polyglycerol fatty acid esters (food grade), 36.0 parts maltitol (purity ≥99%), and 30.0 parts deionized water.

[0079] The product was tested using the same Aw measurement method as in Example 1, and the outer layer Aw was 0.68 and the inner layer Aw was 0.82.

[0080] Comparative Example 3

[0081] The formulation and preparation method of this comparative example are basically the same as those of Example 1. The only difference is that in step (5), the packaging material is replaced with ordinary polyethylene (PE) film, and no desiccant is added.

[0082] Comparative Example 4

[0083] This comparative example cites the closest prior art (taking published patent CN117044788B as an example), whose product has a double-layer structure (outer cheese shell + inner molten filling) and claims a shelf life of 6 months at room temperature.

[0084] Test case

[0085] The products prepared in the above examples and comparative examples were stored at room temperature (25±2℃). Comparative Example 4 (existing technology product) was tested after 6 months of storage, while the remaining samples were tested uniformly after 9 months of storage. The test indicators and specific methods are as follows:

[0086] Test metrics:

[0087] ①Water activity determination: AquaLab 4TE water activity meter was used. 5g of sample was equilibrated at 25℃ for 30 minutes and then measured. The mean value was taken from three parallel measurements.

[0088] ② Sensory evaluation: A judging panel of 10 professional sensory evaluators will score the samples based on four dimensions: texture (30 points), stringiness (25 points), flowability (25 points), and flavor retention (20 points), and calculate the average total score (out of 100 points). See Table 1 for specific scoring criteria.

[0089] ③ Fiber length measurement: After breaking the sample apart, use a ruler to measure the maximum length (cm) of the continuous fiber formed in the middle layer, and take the average value after 5 parallel measurements. Fiber retention rate = (length after storage / initial length) × 100%.

[0090] ④ Determination of the amount of filling flowing out: Using a TA.XT Plus texture analyzer, a P / 50 probe was used to apply a pressure of 10 N to the center of the sample at a speed of 1 mm / s and hold for 5 seconds. The flowing filling was collected and weighed, and the percentage of flowing out mass was calculated (%).

[0091] ⑤ Leakage rate determination: Store the samples in an environment of 25℃ and 60% RH, and observe and record the surface leakage periodically. Leakage rate = (number of leaking samples / total number of samples) × 100%, with 30 samples per group.

[0092] ⑥ Microbiological index determination: The total number of colonies and the number of molds and yeasts were determined according to GB 4789.2-2022 and GB 4789.15-2016, respectively, and the average value was taken from two parallel determinations.

[0093] Table 1 Sensory Evaluation Dimensions and Scoring Criteria

[0094]

[0095] The sensory evaluation scores of each embodiment and comparative product after storage are summarized in Table 2.

[0096] Table 2 Summary of Sensory Evaluation Scores for Examples and Comparative Products

[0097]

[0098] The key performance test results of each embodiment and comparative product after storage are summarized in Table 3. "No exceedance detected" means that the detected value meets the limit requirements of relevant food safety standards such as GB 7099-2015 "Pastries and Bread".

[0099] Table 3 Comparison of performance test results of each embodiment and comparative example after room temperature storage.

[0100]

[0101] Table 3 shows that the products of Examples 1-4, which utilize the three-layer structure and water activity gradient design of this invention, exhibit excellent overall performance after 9 months of storage, with a string length ≥4.3 cm, a core outflow rate ≥80%, a leakage rate ≤4%, a sensory score ≥88 points, and a shelf life ≥8.5 months. Changing the starch ratio (Example 5) significantly weakens stringability; increasing the emulsification temperature (Example 6) affects the fineness of the core; and decreasing the kneading temperature (Example 7) directly damages the stringability, confirming that the specific process parameters in Example 1 are necessary conditions for achieving optimal overall performance. Eliminating the water activity gradient (Comparative Example 1) leads to a surge in leakage rate and a shortened shelf life; removing the intermediate layer (Comparative Examples 2 and 4) completely eliminates the stringability of the product; and using conventional packaging (Comparative Example 3) results in excessive microbial levels and a significantly shortened shelf life. These results collectively demonstrate that the water activity gradient, three-layer composite structure, and high-barrier stabilization system are indispensable core technical features of this invention.

[0102] In summary, this invention, through the synergistic effect of a three-layer composite structure, water activity gradient, specific formulation and process parameters, and an integrated stabilization system, successfully achieves the product's comprehensive quality of "excellent stringiness, stable flow, and rich taste" while maintaining long-term storage at room temperature, effectively solving a long-standing technical contradiction in the industry.

Claims

1. A multi-layered composite molten cheese snack, characterized in that, The molten cheese snack consists of an outer cheese layer, a middle molten glutinous rice skin layer, and an inner molten cheese layer, from the outside to the inside. The outer cheese layer has a water activity (Aw) ≤ 0.65, the middle stretchy glutinous rice skin layer has a water activity of 0.70-0.75, and the inner flowing cheese layer has a water activity of 0.80-0.85, thus forming a water activity gradient system from the outside to the inside.

2. The molten cheese snack according to claim 1, characterized in that, The mass ratio of the outer cheese layer, the middle stretchy glutinous rice skin layer and the inner flowing cheese layer is (55-65):(25-35):(8-12).

3. The molten, stretchy cheese snack according to claim 1, characterized in that, The middle glutinous rice skin layer comprises glutinous rice flour, tapioca starch, hydroxypropyl starch phosphate and glyceryl monostearate, wherein the mass ratio of glutinous rice flour to tapioca starch is (1.5-2.5):

1.

4. The molten, stretchy cheese snack according to claim 1, characterized in that, The inner molten cheese layer comprises natural cheese, whey protein, edible gelatin, sugar alcohol, and emulsifiers; the emulsifiers include glyceryl monostearate and / or polyglycerol fatty acid esters.

5. The molten, stretchy cheese snack according to claim 1, characterized in that, The outer cheese layer comprises cream cheese, whole milk powder, sugar alcohols, and polyglycerol fatty acid esters.

6. A method for preparing a molten, stretchy cheese snack as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Preparation of the molten cheese filling: Mix natural cheese, whey protein, sugar alcohol, edible gelatin, emulsifier and water, and perform vacuum homogenization and emulsification at 60-65℃ and 15-25 MPa pressure to obtain a molten cheese filling with a water activity (Aw) of 0.80-0.85, and cool it for later use; S2. Preparation of the middle stretchable glutinous rice skin material: Mix glutinous rice flour, tapioca starch, hydroxypropyl starch phosphate, glyceryl monostearate and water to form a dough, steam and gelatinize it, knead it at a constant temperature of 38-42℃, and press it into a skin. The water activity (Aw) of the skin is 0.70-0.

75. S3. Preparation of outer cheese base: Mix cream cheese, whole milk powder, sugar alcohol, polyglycerol fatty acid ester and water, stir and whip at 45-55℃ to prepare a cheese base with a water activity (Aw) ≤0.65; S4. Composite molding and packaging: The glutinous rice skin material obtained in S2 is wrapped with the molten cheese paste obtained in S1 to form a sandwich core. The sandwich core is then wrapped with the outer cheese base material obtained in S3 to form the product. The formed product is vacuum-packed with high-barrier material and a composite desiccant is added inside the packaging. Then, pasteurization is performed.

7. The method according to claim 6, characterized in that, The temperature of vacuum homogenization emulsification in step S1 is 62°C and the pressure is 20 MPa.

8. The method according to claim 6, characterized in that, The temperature for constant temperature kneading in step S2 is 40°C.

9. The method according to claim 6, characterized in that, The high-barrier material mentioned in step S4 is a PET / AL / PE composite film; the composite desiccant is a mixture of silica gel and montmorillonite.

10. The method according to claim 6, characterized in that, The pasteurization conditions described in step S4 are a 60°C water bath for 15-20 minutes.

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