Preparation method of baked frozen-to-fresh soft-keeping anti-freezing dough

Abstract

The invention discloses a preparation method of baked frozen-to-fresh soft-keeping anti-freezing dough, relates to the technical field of food processing, and aims to solve the problems that in the prior art, anti-starch aging and anti-freezing components are antagonistic in performance, and a product is not natural in taste and insufficient in softness after being reheated. According to the method, four types of emulsified, thickened, wiredrawing and anti-freezing modified starch, two types of sugar, four types of colloids and soya bean lecithin are selected and compounded; and specific multi-stage thermal-mechanical coupling processing technologies such as ultrahigh-temperature gelatinization, steaming refining, homogeneous emulsification, high-temperature disinfection and the like are adopted. By the adoption of the technical scheme, starch aging and ice crystal formation can be effectively inhibited, the anti-freezing performance is remarkably improved, it is ensured that the product is soft and fluffy in taste after being frozen, stored and reheated, and the quality comparable with that of an on-site baked product is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and in particular relates to a method for preparing baked frozen dough that is fresh-keeping soft and anti-freezing. Background Art

[0002] In the modern food industry, with the rapid changes in supply chain management, standardized production, and consumption patterns, the technology of frozen dough and pre-baked frozen baked products has made great progress. This technology uses centralized and standardized pre-processing or full cooking of bread and other baked products in the factory, and then uses rapid freezing technology for storage and transportation. Finally, it can be eaten at the retail terminal or the consumer's home with just a simple reheating step. This model greatly improves production efficiency, reduces store operating costs and technical barriers, and effectively extends the shelf life of the product. Therefore, it shows broad application prospects in the chain restaurant, supermarket retail and household consumption markets. However, in order to achieve a final quality comparable to freshly baked products, this technical route places extremely high demands on the physical and chemical stability of the product during frozen storage and reheating.

[0003] To address these challenges, existing technologies generally focus on two core issues: inhibiting starch retrogradation and controlling the formation and growth of ice crystals. Specifically, starch retrogradation is the root cause of bread's dry, hard, and crumbly texture after storage and reheating. Under low temperatures, the amorphous amylose and amylopectin chains, once gelatinized, rearrange themselves into an ordered, crystalline double helix. This process is accompanied by the migration and release of water molecules, manifesting macroscopically as a tightening and hardening of the bread crumb structure. A commonly used solution in the industry is the addition of emulsifiers, such as glyceryl monostearate. The mechanism of action lies in the fact that the hydrophobic end of the emulsifier forms a complex with the helical structure of amylose, effectively inhibiting the reassociation and crystallization of starch molecules and, to a certain extent, slowing the retrogradation process. Furthermore, during freezing, internal moisture crystallizes to form ice crystals. The size, morphology, and distribution of ice crystals directly determine whether the microstructure of the dough or bread will suffer irreversible physical damage. Slow freezing or temperature fluctuations can cause small ice crystals to melt and accumulate toward larger ones, forming coarse ice crystals that pierce the gluten network and starch granules, leading to structural collapse and severe water loss after reheating. To this end, existing technologies often introduce hydrophilic colloids (such as xanthan gum, guar gum, etc.) or specific sugars (such as trehalose) as antifreeze agents. These substances can combine with free water, raising the glass transition temperature of the system and increasing the viscosity of the unfrozen water phase, thereby physically hindering the formation and growth of ice crystal nuclei and protecting the structural integrity of the product.

[0004] However, as market demands for sensory quality in pre-baked products increasingly approach "freshly baked" quality, the inherent principles of the aforementioned technical solutions, based on the simple addition of single functional components, have gradually revealed profound limitations in meeting these new challenges. These limitations stem not from the functional deficiencies of individual additives, but rather from the inherent performance antagonism and functional interference within the complex system composed of multiple functional components. This is due to the fact that the emulsifiers added to achieve the desired anti-starch retrogradation effect, through complexation with starch molecules, not only alter the starch's conformation but also subtly alter the distribution of the water environment surrounding the starch granules. This alteration can affect the binding efficiency of antifreeze agents (such as hydrocolloids) with water molecules, compromising their effectiveness in binding free water and inhibiting ice crystals. Furthermore, to achieve adequate antifreeze protection, technicians often need to increase the amount of hydrocolloid added. While high concentrations of colloids do build a strong hydration network, effectively controlling ice crystals, this strong network can become an obstacle to achieving an ideal mouthfeel after the product is reheated. It will cause the bread crumb to have an unnatural wet and sticky feeling or an overly tough and elastic texture after reheating, which is far from the fluffy, soft and melt-in-the-mouth sensory profile of freshly baked bread. This phenomenon that the component introduced to improve performance A (antifreeze resistance) sacrifices performance B (restoring taste) in the final application scenario constitutes the core contradiction of current technology. This strategy of "functional superposition" rather than "system synergy" results in the final product only avoiding the worst result (dry and hard), but it is difficult to achieve the optimal goal (freshly baked feeling). Its taste is often the product of a compromise between "dry and hard" and "wet and sticky".

[0005] Therefore, how to break through the traditional mindset of simple compounding of single-functional components and develop a new compound system that can not only effectively inhibit starch retrogradation and ice crystal growth at the molecular level, but more importantly, avoid performance antagonism between functional components, ensuring that while achieving excellent antifreeze properties, it can synergistically reconstruct a porous, soft and elastic internal structure close to that of freshly baked products after reheating. This has become a key challenge and a technical problem that needs to be solved urgently by technicians in this field. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for preparing a frozen dough that can be baked and turned into fresh, soft and antifreeze dough, aiming to overcome the performance antagonism between the anti-starch aging component and the antifreeze component in the prior art. The prior art simply compounded an emulsifier with a hydrophilic colloid, which often resulted in the final product sacrificing the sensory quality after reheating while pursuing antifreeze protection, presenting an unnatural wet and sticky or tough and elastic texture, and failing to achieve a soft and fluffy taste comparable to freshly baked products. The present invention aims to achieve, on the basis of efficiently inhibiting ice crystal formation and starch retrogradation, ensuring that the dough can reconstruct an ideal microstructure and macroscopic sensory characteristics close to freshly baked products after undergoing a freeze-thaw-reheating cycle.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] A method for preparing a frozen, fresh-keeping, and frost-resistant dough involves compounding four types of modified starch (emulsifying, thickening, stringing, and antifreeze) with two types of sugar (seaweed and glucose) and four types of colloids (xanthan gum, carrageenan, gum arabic, and locust bean gum) to enhance viscosity. Soy lecithin is then added to enhance its overall emulsifying properties, and the dough is neutralized with water. The dough undergoes an ultra-high temperature gelatinization process, followed by a steaming and refining process, followed by a homogenizing emulsification process. The dough is then sterilized, packaged, cooled, air-dried, and packed in boxes for refrigerated storage.

[0009] The present invention, through the above-mentioned technical solution, is used to improve and slow the aging of wheat starch in frozen, fully cooked pre-made bread products, blocking the formation of ice crystals within the bread structure, thereby giving the products excellent antifreeze properties. The technical solution of the present invention effectively restores the taste of pre-made baked products that have been frozen and stored after reheating, achieving sensory quality that is highly consistent with freshly baked bread products. The soft-keeping antifreeze composition obtained by the preparation method is added to frozen-to-fresh fully cooked frozen products in an amount set to 10% to 20% of the total product mass, and under specified refrigerated conditions, its shelf life is 180 days.

[0010] As a specific implementation of the technical solution of the present invention, the preparation method comprises the following ordered process steps, aiming to construct a stable colloidal dispersion system with specific molecular structure and physical properties.

[0011] First, the raw materials are pretreated and accurately weighed. The four types of modified starch, two types of sugar, four types of colloid, soy lecithin and process water are accurately weighed according to the preset formula ratio.

[0012] Specifically, the emulsified modified starch is octenyl succinate starch ester, the degree of substitution of which is 0.015 to 0.020, and the Brookfield viscometer value of a 5% concentration paste thereof at 25° C. is 50 to 150 mPa·s.

[0013] The thickening modified starch is acetylated distarch phosphate, which has an acetyl content of 1.5% to 2.5%, a gelatinization starting temperature of 60° C. to 65° C., and has the characteristics of high viscosity, high transparency and shear resistance.

[0014] The stringy modified starch is a cross-linked esterified starch with a high amylose content, wherein the amylose content is greater than 50%, and the starch has significant film-forming property and ductility after gelatinization.

[0015] The antifreeze modified starch is hydroxypropyl distarch phosphate, the hydroxypropyl substitution molar number of which is 0.05 to 0.15, and has excellent freeze-thaw stability. After multiple freeze-thaw cycles, the water separation rate of the paste is less than 5%.

[0016] Among the two types of sugars, trehalose is dihydrated trehalose connected by α,α-1,1-glycosidic bonds, with a purity greater than 99.0%; and glucose is monohydrated D-glucose, with a purity greater than 99.5%.

[0017] Among the four types of colloids, the xanthan gum is 80 mesh food grade xanthan gum, and the viscosity of its 1% saline solution is not less than 1200mPa·s; the carrageenan is κ-type refined carrageenan, and its gel strength is not less than 1000g / cm at a concentration of 1.5% and in the presence of 0.2% potassium chloride. 2 The gum arabic is spray-dried Acacia gum with a molecular weight distribution between 250,000 and 600,000 Daltons. The locust bean gum is 100 mesh food-grade locust bean gum with a 1% aqueous solution viscosity of 2,500 to 3,500 mPa·s.

[0018] The soybean lecithin is deoiled and purified powdered soybean lecithin, and its phosphatidylcholine (PC) content is not less than 30%.

[0019] The water is purified water that has been treated with reverse osmosis and has an electrical conductivity of less than 5 μS / cm.

[0020] Furthermore, the core of the preparation method lies in a multi-stage, synergistic preparation process. This process is not a simple physical mixing, but through the precise control of thermodynamic conditions and fluid dynamics, it induces the ordered self-assembly of each component at the molecular scale to form a hierarchical supramolecular network structure. The preparation process specifically includes the following sequential unit operations:

[0021] Phase 1: Primary Complex Construction. The formulated amount of soy lecithin and emulsified modified starch (octenyl succinate starch ester) are first mixed with a portion of the process water (20% to 30% of the total water usage) in a premix tank equipped with a jacket and high-shear agitation. High-shear agitation is initiated, the speed set to 3000 to 5000 rpm, and the jacket temperature raised to 65°C to 75°C. Shear dispersion is maintained under these conditions for 15 to 25 minutes. This step aims to utilize the amphiphilic structure formed by the hydrophobic octenyl groups on the starch octenyl succinate molecular chains and the hydrophilic starch backbone as a molecular chaperone to highly disperse and encapsulate the soy lecithin molecules, forming primary starch-lipid complex micelles with a phospholipid core and a modified starch shell. The formation of this complex is the first barrier to inhibit starch retrogradation. It stabilizes and encapsulates lipid molecules that would otherwise readily form complexes with amylose, preventing them from undesirably interfering with other functional components in the subsequent dough system.

[0022] The second stage: pre-formation of the polymer hydration network. In another independent dissolution tank with stirring and heating functions, the four colloids of xanthan gum, carrageenan, gum arabic and locust bean gum are dry-mixed with the formulated amounts of trehalose and glucose to prevent the colloids from agglomerating when entering the water. The dry-mixed powder is slowly added to the remaining process water (accounting for 70% to 80% of the total water consumption) and stirred continuously at medium speed (300 to 500 rpm) for 30 to 40 minutes until all the powders are completely dispersed without agglomerates. Subsequently, the temperature in the tank is slowly raised to 80°C to 85°C and kept warm for 20 minutes to ensure that all colloidal molecular chains are fully hydrated and stretched. During this process, xanthan gum and locust bean gum molecules interact synergistically, forming the initial framework of a thermoreversible gel network. Under heating and the presence of ions (triggered by trace ions in the raw materials), kappa-carrageenan forms a double helical structure, further enhancing the network's rigidity. Gum arabic, a highly branched polysaccharide-protein complex, provides steric stabilization and emulsification within the network. This step creates a macroscopically uniform, hydrated polymer network with high water-holding capacity.

[0023] Phase 3: Integration of functional starches and matrix construction. After dry-mixing the formulated amounts of thickening modified starch, stringing modified starch, and antifreeze modified starch, slowly add them to the polymer hydrated network system prepared in the second phase. While maintaining a temperature of 80°C to 85°C and stirring at medium speed, continue mixing for 15 to 20 minutes. The purpose of this step is to evenly disperse and embed the three types of functional starch particles into the pre-formed colloidal network. The thickening modified starch begins to gelatinize at this temperature, filling the voids in the colloidal network and further improving the viscosity and stability of the system. After gelatinization, the high-amylose molecules of the stringing modified starch will interpenetrate with the colloidal network, providing the necessary ductility and chewiness for the texture of the final product after reheating. The antifreeze modified starch, with its excellent hydrophilicity and steric hindrance effect, together with trehalose, secondary binds the bound water and free water in the colloidal network, greatly increasing the glass transition temperature of the system.

[0024] Stage 4: Ultrahigh Temperature Sterilization and Molecular-Level Homogenization. The primary starch-lipid complex micellar suspension prepared in Stage 1 is precisely pumped into the composite polymer matrix prepared in Stage 3 via a metering pump. Initial mixing is performed in-line using a static mixer. The mixture is then immediately pumped into an ultrahigh temperature (UHT) sterilization system. This UHT system utilizes a shell-and-tube or plate heat exchanger coupled with a steam injection heater. The material is first preheated to 90°C to 95°C. Then, using direct steam injection, it is rapidly heated to 138°C to 145°C within 0.1 to 0.3 seconds and maintained at this temperature for 3 to 5 seconds. This step not only achieves commercial sterility but also, crucially, utilizes ultrahigh temperature and high turbulence to force all polymer chains (including starch and colloids) to instantaneously achieve complete dissolution and maximum extension, breaking down any remaining aggregates and crystalline structures and creating a uniform, high-energy molecular melt for subsequent orderly reconstruction.

[0025] Stage 5: Steaming-Flash Cooling and Initial Network Structure Formation. The high-temperature material, after UHT treatment, is immediately flash-evaporated into a vacuum retort at a vacuum level of -0.06 to -0.08 MPa. The sudden drop in pressure instantly lowers the material temperature to 85°C to 95°C, evaporating some of the water and removing any odor molecules that may have been generated during processing. This "steaming" process is accompanied by slow, large-blade agitation within the retort. This controlled, rapid cooling process is a key step in inducing the formation of the supramolecular network structure. At this cooling rate, polymers of varying molecular weights, based on their thermodynamic properties, begin to undergo orderly molecular rearrangement and association. A synergistic network of xanthan gum and locust bean gum preferentially forms, forming the primary backbone of the system. The double helix structure of κ-carrageenan stabilizes within this temperature range. The gelatinized starch chains (including modified starch and starch from flour in subsequent applications) are physically separated and fixed within this complex colloidal network, their rearrangement and crystallization potential (i.e., retrogradation) being significantly limited by steric hindrance.

[0026] Stage 6: High-pressure homogenization and final stabilization of the emulsified system. The material, still at 85°C to 90°C, is immediately pumped into a two-stage high-pressure homogenizer. The first-stage homogenization pressure is set at 25 to 35 MPa, and the second-stage homogenization pressure is set at 3 to 5 MPa. High-pressure homogenization has multiple functions: First, it further breaks up and disperses the primary starch-lipid complex introduced in the fourth stage, uniformly distributing it at nano- or submicron-scale throughout the polymer network matrix, forming an extremely stable O / W emulsified system. Second, the strong shear force and cavitation effect further promote the interpenetration and entanglement of polymer chains, making the resulting composite network structure more dense and uniform. Third, the lower pressure of the second-stage homogenization is primarily used to prevent the reaggregation of fine particles after homogenization, ensuring the long-term physical stability of the system.

[0027] Stage 7: Aseptic Filling and Controlled-Rate Cooling. After high-pressure homogenization, the final product—the baked frozen-to-fresh, soft-soft antifreeze composition slurry—is conveyed to an aseptic filling system, maintained at a temperature of no less than 80°C. Under a Class 100 cleanroom environment, it is quantitatively filled into multi-layer composite film bags that have been sterilized with hydrogen peroxide or irradiation and heat-sealed. The sealed bags immediately enter a multi-stage, countercurrent spray cooling tunnel. By precisely controlling the cooling water temperature in different zones, the product temperature is steadily lowered from over 80°C to 25°C to 30°C over 30 to 40 minutes. This controlled-rate cooling process avoids thermal stress caused by large temperature differences and allows the polymer network to anneal to its lowest energy, most stable state, thereby locking in the fine microstructure formed after homogenization.

[0028] Finally, the cooled products are dried on the surface of the packaging, quality inspected, and coded before being packed and stored in a cold storage with a temperature controlled between 2°C and 8°C.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] First, through systematic process design, the problem of performance antagonism is fundamentally solved. The present invention does not simply mix the emulsifier and antifreeze agent, but rather spatially isolates the two functional systems by constructing a "primary starch-lipid complex" and embedding it as the dispersed phase into the "composite colloid-functional starch" continuous phase matrix. This allows soy lecithin to focus on interacting with starch and delaying its aging without interfering with the water-holding function of the colloid system; at the same time, the composite colloid network can also maximize its role in binding water and inhibiting ice crystal growth. The two perform their respective functions and synergize to enhance their effectiveness.

[0031] Second, a multi-layered, multi-dimensional antifreeze and water-retention barrier is constructed. The antifreeze mechanism of this invention is three-dimensional: macroscopically, a three-dimensional gel network composed of xanthan gum, locust bean gum, and carrageenan serves as the first barrier, physically hindering the formation of large ice crystals. Microscopically, the antifreeze-modified starch, trehalose, and glucose filling this network form a second molecular barrier by increasing the viscosity of unfrozen water, reducing water activity, and raising the glass transition temperature. Furthermore, highly dispersed gum arabic and starch-lipid complexes after homogenization act as tiny "hydration centers," further segmenting and refining the aqueous phase. This multi-layered protection system ensures that the product maintains its microstructural integrity during long-term storage at temperatures of -18°C or even lower.

[0032] Third, the "freshly baked level" restoration of the taste after reheating is achieved. In the prior art, high amounts of colloids added often cause the bread to become sticky and tough after reheating. The present invention introduces wire-drawn modified starch and precisely controls the colloid network structure, so that the network exhibits high water retention and structural strength at room temperature and in a frozen state. However, at the baking and reheating temperature (such as 150°C-180°C), part of the network structure (such as the xanthan gum-locust bean gum synergistic network) will undergo thermoreversible partial dissociation, thereby releasing an appropriate amount of water to form steam, which makes the bread crumb fluffy, moist but not sticky. At the same time, the amylose molecules fixed by the network are effectively isolated and cannot be regenerated in large quantities, thereby ensuring the softness of the bread. Ultimately, the reheated product presents a comprehensive quality that is very similar to freshly baked bread, such as being porous, soft, elastic, and having a good taste in the mouth.

[0033] Fourth, precise control of the process ensures the high stability and uniformity of the product. The present invention organically integrates modern food engineering technologies such as ultra-high temperature instantaneous sterilization, vacuum flash cooling, and high-pressure homogenization into a continuous, controlled processing flow. Each step not only serves its traditional purpose (such as sterilization and cooling), but is also endowed with the key function of regulating the microstructure of the product. This design based on process engineering principles ensures that each batch of products has the same, preset molecular network structure and physicochemical properties, ensuring the high consistency and reliability of its application effect in industrial large-scale production. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. What the present invention aims to achieve is a method for preparing a baked frozen dough that is fresh and soft and anti-freeze. The core of the method is to construct a composite colloidal system composed of specific components that are self-assembled in an orderly manner at the molecular scale through a multi-stage, precision process coupled with thermal and mechanical forces. When applied to frozen dough and prefabricated baked products, this system can synergistically exert the dual effects of resisting starch aging and inhibiting ice crystal growth, thereby giving the final product, after undergoing a complete freeze-thaw-reheat cycle, the ideal sensory quality and microstructure close to that of freshly baked food.

[0035] The preparation method disclosed herein begins with the rigorous screening and precise proportioning of a series of functional raw and auxiliary materials with specific physicochemical properties. These raw and auxiliary materials are not simply a superposition of functions; rather, they serve as the fundamental building blocks for constructing the final hierarchical supramolecular network structure, each playing an essential or irreplaceable role. In one specific embodiment, the raw material system and technical specifications involved in the preparation method are precisely defined.

[0036] Specifically, the raw material system contains four types of modified starches that have undergone special modification treatments. The first type is emulsified modified starch, whose chemical nature is octenyl succinate starch ester. In order to ensure that it can efficiently coat lipid molecules in subsequent processes to form a stable starch-lipid complex, its degree of substitution is strictly controlled within the range of 0.015 to 0.020. This degree of substitution range can give the starch molecular chain sufficient hydrophobic octenyl groups to anchor lipid molecules while maintaining the good water solubility of its hydrophilic starch backbone. Its physical properties are characterized by the Brookfield viscometer value of its 5% concentration paste at 25 degrees Celsius. The viscosity value is set between 50 and 150 mPa·s. This viscosity range not only ensures its good fluidity and dispersibility in the premixing stage, but also indicates its appropriate molecular size and conformation in the aqueous phase.

[0037] The second category is thickening modified starch, which uses acetylated distarch phosphate. The core function of this type of starch is to fill the gaps in the colloidal network skeleton and provide basic viscosity and texture for the entire system. Its acetyl content is controlled at 1.5% to 2.5%, and this indicator is directly related to its transparency and anti-aging properties after gelatinization. At the same time, its cross-linked structure gives it excellent shear and acid resistance, ensuring that the molecular chain is not easily broken during subsequent high-temperature and high-shear processing. Its gelatinization starting temperature is set at 60°C to 65°C, and this feature enables it to be precisely activated at a specific process stage.

[0038] The third category is stringy modified starch, which is essentially a cross-linked esterified starch with a high amylose content. Its amylose content is required to be greater than 50%. This high amylose ratio is key to its ability to form a network structure with remarkable ductility and film-forming properties after gelatinization. In the final baked product, it is these starch chains interspersed within the colloidal network that impart the excellent toughness and ductility perceived during chewing, simulating the unique texture of toasted bread.

[0039] The fourth category is antifreeze modified starch, which uses hydroxypropyl distarch phosphate. Its core function is to introduce hydroxypropyl groups through molecular modification, which greatly enhances the hydrophilicity and steric hindrance effect of starch molecules, thereby effectively binding water and inhibiting its migration and formation of large ice crystals during the freezing process. Its hydroxypropyl substitution molar number (MS) is controlled within the range of 0.05 to 0.15, which is a guarantee for achieving excellent freeze-thaw stability. Its performance is quantified by the water separation rate of the paste after multiple freeze-thaw cycles, which is required to be less than 5%, which directly proves its strong water-holding and antifreeze capabilities.

[0040] In addition to the four types of functional starches mentioned above, the raw material system also includes two specific types of sugars, which act as small molecule cryoprotectants and water activity regulators, synergistically acting with high molecular weight polymers. The first is trehalose, specifically α,α-1,1-glycosidically linked dihydrate trehalose with a purity greater than 99.0%. Trehalose, with its unique molecular structure, can form an amorphous glassy matrix near the freezing point of water, effectively fixing water molecules in its hydration layer, thereby significantly increasing the glass transition temperature of the system and thermodynamically inhibiting the formation and growth of ice crystals. The second is glucose, specifically D-glucose monohydrate with a purity greater than 99.5%. Glucose, as a monosaccharide, can effectively reduce the water activity of the system and serve as a cost-effective filler and sweetness regulator.

[0041] Furthermore, the core components of constructing the macroscopic three-dimensional network skeleton are four types of carefully selected hydrophilic colloids. The first is xanthan gum, and 80-mesh food-grade xanthan gum is selected. Its key performance indicator is that the viscosity of its 1% saline solution is not less than 1200mPa·s. This high viscosity characteristic is the basis for it to form a stable pseudoplastic fluid network at extremely low concentrations. The second is carrageenan, and specifically κ-type refined carrageenan is selected. Its ability to form a thermoreversible rigid gel in the presence of specific ions (such as potassium ions) is its key function, and its gel strength is required to be not less than 1000g / cm at a concentration of 1.5% and in the presence of 0.2% potassium chloride. 2 To ensure that the network skeleton has sufficient mechanical strength. The third type is gum arabic, which is made from spray-dried Acacia gum. Its molecular weight distribution ranges from 250,000 to 600,000 Daltons. This highly branched polysaccharide-protein complex not only acts as an emulsifier and stabilizer in the system in conjunction with soybean lecithin, but also plays a filling and stabilizing role in the colloidal network with its huge steric hindrance effect. The fourth type is locust bean gum, which uses 100 mesh food-grade locust bean gum. The viscosity of its 1% aqueous solution is required to be in the range of 2500 to 3500 mPa·s. Its most important characteristic is that it can have a significant synergistic effect with xanthan gum, forming a composite network with gel strength and elasticity far exceeding what can be achieved when either is used alone.

[0042] The system also includes a key emulsifier, soy lecithin. To ensure maximum emulsification efficiency and affinity with starch molecules, deoiled and purified powdered soy lecithin is used, with a minimum content of its core functional ingredient, phosphatidylcholine (PC), of 30%.

[0043] Finally, the dispersion medium for all the above components is process water, which must be purified water treated by reverse osmosis and have a conductivity requirement of less than 5 μS / cm to eliminate the uncontrollable effects of inorganic salt ions on colloidal behavior and system stability.

[0044] Based on this precisely defined raw material system, the core of this invention lies in a meticulously designed, interconnected, multi-stage preparation process. This process goes beyond simple physical mixing, but rather, through precise control of thermodynamic parameters and fluid dynamics, guides the orderly self-assembly of the components at the molecular level, ultimately forming a structurally stable, functionally synergistic, hierarchical network system.

[0045] The first stage of the preparation process is the construction of the primary complex. The goal of this step is to pre-stabilize the functional lipid molecules. The total amount of powdered soy lecithin and emulsified modified starch (octenyl succinate starch) is placed in a stainless steel premixing tank equipped with a jacket and high-shear agitation system. Purified water, representing 20% ​​to 30% of the total process water, is added. The high-shear agitator is then started and set to a high turbulence state, specifically 3,000 to 5,000 rpm. Simultaneously, steam or hot water is introduced into the tank through the jacket to precisely raise the material temperature to 65°C to 75°C. Under this temperature coupled with shear forces, dispersion is continued for 15 to 25 minutes. During this process, the molecular chains of the octenyl succinate starch are fully extended by the action of thermal and mechanical energy. The hydrophobic octenyl groups on the chains spontaneously align with and coat the similarly hydrophobic soy lecithin molecules, while the hydrophilic starch backbones align with the aqueous phase. Ultimately, a primary starch-lipid complex micelle with a submicron particle size is formed, with phospholipid molecules or their micelles as the core and modified starch molecules as the shell. This pre-encapsulated structure lays the foundation for the subsequent construction of a stable O / W emulsification system and avoids unintended reactions that may be caused by free phospholipid molecules in subsequent processes.

[0046] The second stage is the pre-formation of the polymer hydration network. In a separate dissolution tank equipped with a jacket and a medium-speed impeller (such as an anchor or frame impeller), the formulated amounts of xanthan gum, kappa-carrageenan, gum arabic, and locust bean gum are first thoroughly dry-premixed with the formulated amounts of trehalose and glucose. This operation is a key pretreatment step to prevent the polymer colloids from forming difficult-to-disperse clumps due to rapid surface hydration when in contact with water. Subsequently, the remaining 70% to 80% of the process water is added to the dissolution tank, and medium-speed stirring is started, with the speed controlled at 300 to 500 rpm to form a vortex that can effectively entrain the powder. The dry-mixed powder is then sprinkled into the vortex using a Venturi feeder or slowly manually, and stirring is continued for 30 to 40 minutes until all powder is completely dispersed and no visible particles or lumps are confirmed by visual inspection and wall scraping. The tank contents are then slowly heated via the jacket, raising the temperature to 80°C to 85°C and maintaining this temperature for 20 minutes. This heat treatment ensures that all polymer chains, particularly the xanthan gum and locust bean gum, are fully hydrated and achieve a fully extended conformation, creating the conditions for their synergistic interaction. During this stage, a macroscopically uniform, hydrated polymer network with high water-holding capacity is initially formed.

[0047] The third stage of the process is the integration of functional starch and matrix construction. While maintaining the material temperature in the second-stage dissolution tank at 80°C to 85°C and continuous stirring, the three types of functional starches, namely, thickening modified starch, drawing modified starch and antifreeze modified starch, which have been pre-dry mixed, are slowly added to the already formed polymer hydrated network system. Continue mixing at this temperature and medium-speed stirring for 15 to 20 minutes. The purpose of this step is to use the already formed high-viscosity colloidal network as a dispersion medium to evenly suspend and embed the functional starch particles therein to prevent the starch particles from settling or agglomerating. At this temperature, the thickening modified starch (acetylated distarch phosphate) begins to gelatinize, and its dissolved molecular chains fill the gaps in the colloidal network, further improving the viscosity and stability of the entire system. The drawing modified starch and antifreeze modified starch are evenly dispersed and fixed in the form of particles, preparing for subsequent ultra-high temperature treatment.

[0048] The fourth stage, a core component of the entire process, involves ultrahigh temperature instantaneous sterilization (UHT) and molecular-level homogenization. The primary starch-lipid complex prepared in suspension form in the first stage is precisely pumped into the pipeline carrying the composite polymer matrix prepared in the third stage via a precision metering pump at a preset flow rate. A static mixer is installed in the pipeline to ensure initial, uniform mixing of the two streams before entering the UHT system. The mixture is then immediately pumped into an ultrahigh temperature instantaneous sterilization (UHT) system, which preferably combines a shell-and-tube heat exchanger with a direct steam injection heater. The material is first preheated to 90°C to 95°C in the shell-and-tube heat exchanger before entering the steam injection chamber. High-pressure clean steam is injected directly into the material stream, rapidly raising the temperature to the sterilization temperature of 138°C to 145°C in a very short time (0.1 to 0.3 seconds). This high temperature is maintained in a holding tube for 3 to 5 seconds. This step is far more significant than commercial sterilization. The ultra-high temperature and the accompanying violent turbulence provide the system with a huge energy input, which is enough to forcibly break the crystal structure of all starch granules, causing all polymer chains including modified starch and colloids to instantly reach a state of complete dissolution and maximum extension, forming a molecular melt that is physically highly uniform and chemically in a high-energy activated state.

[0049] The next fifth stage involves steaming, flash cooling, and the initial formation of the network structure. The high-temperature, high-pressure UHT material is immediately introduced into a vacuum retort connected to a vacuum system. The vacuum level in the retort is precisely controlled within the range of -0.06 to -0.08 MPa. When the high-temperature material enters this low-pressure environment, a violent flash evaporation occurs, instantly reducing the material temperature to 85°C to 95°C. This process not only removes the excess moisture introduced by the steam injection, restoring the product solids content to the formulated target, but also removes any odor molecules that may have been generated during processing. Simultaneously with the flash evaporation, a low-speed (e.g., 15-30 rpm) large-blade scraping agitator within the retort gently stirs the material, promoting uniform heat and mass transfer and preventing coking on the retort walls. This controlled, rapid, rather than slow, cooling process is key to inducing the orderly formation of the supramolecular network. Within this cooling rate and temperature range, polymers of different molecular weights begin to rearrange and associate according to their thermodynamic properties. The dissolved xanthan gum and locust bean gum chains work synergistically to preferentially form a gel network that constitutes the system's macroscopic skeleton. The double helix structure of κ-carrageenan also stabilizes at this temperature. The fully gelatinized, freely extended starch chains are separated, encapsulated, and fixed by this rapidly formed, physical, composite colloidal network. Consequently, the tendency of these chains to approach each other and rearrange and crystallize (i.e., starch retrogradation) is significantly limited by steric hindrance.

[0050] The sixth stage of the process involves high-pressure homogenization and final stabilization of the emulsified system. The hot material, still maintained at 85°C to 90°C, is immediately pumped into a second-stage high-pressure homogenizer via a high-pressure pump before it cools significantly. The homogenization process parameters are precisely set: the pressure of the first-stage homogenizer valve is set at 25 to 35 MPa, and the pressure of the second-stage homogenizer valve is set at 3 to 5 MPa. This high-pressure homogenization step has multiple crucial functions. First, the strong shear forces, cavitation, and impact effects generated by the high pressure in the first stage further break down and disperse the primary starch-lipid complex introduced in the fourth stage, which may have undergone some changes during UHT. Ultimately, the starch-lipid complex is dispersed extremely uniformly throughout the polymer network matrix in nano- or submicron-sized droplets, forming an O / W emulsion system with extremely high long-term stability. Secondly, this strong mechanical energy input further promotes the interpenetration and physical entanglement of all polymer chains (starch and colloid) within the system, making the final composite network structure more dense, uniform, and strong. Thirdly, the lower homogenization pressure in the second stage is mainly used to break up the instantaneous reaggregation of small emulsion droplets that may occur after the first stage of homogenization, ensuring that the dispersion state of the emulsion system is permanently fixed.

[0051] The seventh and final stage is aseptic filling and controlled-rate cooling. After high-pressure homogenization, the final product—the baked frozen-to-fresh, soft-soft antifreeze composition slurry—is conveyed to a fully automated aseptic filling system, maintained at a temperature of no less than 80°C via a plate heat exchanger. Under a Class 100 cleanliness level, the slurry is metered into multi-layer composite film packaging bags (e.g., PET / AL / PA / PE composites) that have been sterilized by spraying with hydrogen peroxide solution or electron beam irradiation and immediately heat-sealed. The sealed bags then enter a multi-stage countercurrent spray cooling channel. This channel is divided into multiple temperature zones. By precisely controlling the spray water temperature in each zone, the product cooling rate is programmably controlled, allowing the product temperature to be smoothly and linearly reduced from above 80°C to room temperature of 25°C to 30°C over a period of 30 to 40 minutes. This controlled cooling process avoids the uneven structure inside the product caused by thermal stress due to excessive temperature differences between the inside and outside, and allows the polymer network structure to undergo a final "annealing" during the cooling process, relaxing to the equilibrium state with the lowest energy and most stable structure, thereby perfectly "locking" the fine microstructure formed after high-pressure homogenization.

[0052] Finally, the cooled product is packaged in bags that have been blown dry with powerful air knives to remove any moisture. After undergoing quality control and labeling procedures such as online weighing, metal detection, and coding, it is packed into outer packaging and immediately stored in a cold storage facility maintained at a strictly controlled temperature of 2°C to 8°C. The composition prepared through this complete process is recommended for addition to frozen-to-fresh, fully cooked products at a rate of 10% to 20% by weight. Under these refrigerated conditions, its physical and chemical properties remain stable, with a shelf life of up to 180 days.

[0053] To further illustrate the technical effects of the present invention, a specific embodiment and comparative example are given below.

[0054] Example 1

[0055] The present embodiment aims to prepare a large amount of a baked frozen freshness-maintaining and antifreeze composition.

[0056] The raw material formula is as follows:

[0057] Octenyl succinate starch ester (degree of substitution 0.018, viscosity 100 mPa·s): 15.0 kg

[0058] Acetylated distarch phosphate (acetyl content 2.0%): 50.0 kg

[0059] High-amylose cross-linked esterified starch (amylose content 55%): 25.0 kg

[0060] Hydroxypropyl distarch phosphate (MS 0.10, water separation <4%): 40.0 kg

[0061] Trehalose dihydrate (purity 99.5%): 50.0 kg

[0062] D-glucose monohydrate (purity 99.8%): 50.0 kg

[0063] Xanthan gum (80 mesh, viscosity 1300 mPa·s): 8.0 kg

[0064] κ-carrageenan (gel strength 1200g / cm 2 ): 3.0kg

[0065] Gum Arabic (spray dried, molecular weight about 400,000 Da): 5.0 kg

[0066] Locust bean gum (100 mesh, viscosity 3000 mPa·s): 2.0 kg

[0067] Powdered soybean lecithin (PC content 35%): 4.0 kg

[0068] Reverse osmosis purified water (conductivity <3μS / cm): 748.0kg

[0069] The preparation process strictly follows the above seven stages:

[0070] Primary complex construction: 4.0 kg of soy lecithin, 15.0 kg of octenyl succinate starch and 224.4 kg (30% of the total water volume) of purified water were added to a high shear premix tank, heated to 70°C and sheared for 20 minutes at 4000 rpm.

[0071] Preformation of a Hydrated Polymer Network: Dry-blend 8.0 kg of xanthan gum, 3.0 kg of carrageenan, 5.0 kg of gum arabic, and 2.0 kg of locust bean gum with 50.0 kg of trehalose and 50.0 kg of glucose. Add this dry-blend powder to a dissolution tank containing the remaining 523.6 kg of purified water. After stirring at 400 rpm for 35 minutes, heat to 82°C and maintain for 20 minutes.

[0072] Functional starch integration: Add a dry mixture of 50.0 kg of acetylated distarch phosphate, 25.0 kg of high-amylose cross-linked esterified starch, and 40.0 kg of hydroxypropyl distarch phosphate to the dissolution tank in step 2 and continue stirring at 82°C for 20 minutes.

[0073] UHT treatment: The complex suspension of step 1 and the composite matrix slurry of step 3 were pumped into a static mixer in proportion, and then pumped into the UHT system and maintained at 142°C for 4 seconds.

[0074] Distillation-flash cooling: The UHT treated material is flashed into a vacuum distillation tank at -0.07MPa, the temperature is reduced to 90℃, and the wall is scraped and stirred at a low speed.

[0075] High-pressure homogenization: The material at 90°C is pumped into the two-stage homogenizer. The first-stage pressure is set to 30MPa and the second-stage pressure is set to 4MPa.

[0076] Aseptic filling and controlled-rate cooling: The homogenized slurry is filled into sterile bags at 85°C and cooled to 28°C within 35 minutes through a spray cooling channel. It is then transferred to a 4°C cold storage for storage.

[0077] Comparative Example 1

[0078] The raw material formulation of this comparative example is exactly the same as that of Example 1.

[0079] The preparation process is as follows: 748.0 kg of purified water is added to a jacketed and stirred mixing tank and heated to 85°C. All dry raw materials (all starches, sugars, colloids, lecithin) are pre-dry mixed. This mixed powder is slowly added to 85°C hot water at one time and stirred continuously at high speed (1000 rpm) for 60 minutes to ensure that all materials are dissolved and gelatinized. Subsequently, the mixture is sterilized through a plate heat exchanger (95°C, 30 seconds), then cooled to 30°C, packaged and stored. This method represents the conventional idea of ​​simple physical mixing of all components.

[0080] The compositions prepared in Example 1 and Comparative Example 1 were each added at a 15% dosage (based on the weight of flour) to prepare fully cooked frozen bread of a standard recipe. After bread production, the bread was frozen and stored at -18°C for 30 days. After removal, the bread was thawed at room temperature for 2 hours and then reheated in a microwave oven (medium-high heat) for 60 seconds. The performance of the reheated bread samples and an unfrozen control sample was evaluated.

[0081] Test indicators include:

[0082] Crumb hardness: The hardness (N) of the center slice of bread was measured 1 hour and 24 hours after reheating using a Texture Analyzer.

[0083] Freeze-thaw water loss rate: Take 100g of dough and measure the mass percentage of precipitated water after one freeze-thaw cycle (-18℃ for 24h -> 25℃ for 4h).

[0084] Specific volume of bread: The volume of bread (mL) was measured by the rapeseed displacement method and divided by its mass (g) to obtain the specific volume (mL / g).

[0085] Sensory evaluation: Ten trained assessors conducted a double-blind scoring (10-point scale) on the bread one hour after reheating, evaluating its softness, moistness, resilience and overall acceptance.

[0086] The test results are summarized in Table 1:

[0087] Table 1

[0088]

[0089] It can be clearly seen from the above data comparison that the composition prepared by the method of the present invention (Example 1) has an application effect significantly better than the composition prepared by a simple mixing method (Comparative Example 1). Specifically, the hardness of the bread prepared in Example 1 is significantly lower than that of Comparative Example 1 after long-term freezing and reheating, and its aging rate (hardness growth rate) is closer to that of freshly baked products. The extremely low freeze-thaw water loss rate directly proves that the composite network system constructed by the present invention has excellent water holding and antifreeze capabilities. In terms of macroscopic morphology, the bread of Example 1 maintains a good specific volume and a fluffy tissue structure, while Comparative Example 1 shows obvious volume shrinkage. Most importantly, in the sensory evaluation, Example 1 obtains high scores close to freshly baked products in multiple dimensions such as softness, moistness, resilience and comprehensive acceptance, while Comparative Example 1 shows obvious texture deterioration, such as hardness, dryness, lack of elasticity, and even localized wet and sticky taste, which fully demonstrates the technical problems solved by the present invention and the significant beneficial effects brought about by it.

[0090] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing a baked frozen dough that is fresh, soft and antifreeze, characterized in that: The following steps are involved: a) Formation of a primary complex: Soy lecithin as an emulsifier, starch octenylsuccinate as an emulsified modified starch, and the first portion of process water are mixed and dispersed at a predetermined temperature and high shear force to form a primary starch-lipid complex micelle suspension having a phospholipid core and a modified starch shell. b) Pre-forming a hydrated polymer network: Pre-mixing a plurality of hydrophilic colloids and a saccharide by dry method, then adding the dry mixed powder to the remaining second portion of process water, stirring and dispersing the mixture, and then heating and heat-insulating the mixture to fully hydrate and extend the hydrophilic colloid molecular chains, thereby forming a macroscopically uniform hydrated polymer network system with high water-holding capacity; c) Integration of functional starch: adding a plurality of functional modified starches to the polymer hydrated network system prepared in step b), and mixing them while maintaining a specific temperature to uniformly disperse and embed the functional starch particles into the preformed colloidal network, thereby constructing a composite polymer matrix; d) ultrahigh temperature treatment and molecular homogenization: the primary starch-lipid complex micelle suspension prepared in step a) is mixed with the composite polymer matrix prepared in step c), and the mixture is immediately pumped into an ultrahigh temperature instantaneous sterilization system for treatment, where ultrahigh temperature and high turbulence are used to force all polymer chains to reach a state of complete dissolution and maximum extension, forming a uniform molecular melt state; e) Steaming-Flash Cooling and Initial Network Structure Formation: The ultra-high temperature material is immediately introduced into a vacuum steaming tank and flash-cooled under vacuum conditions. The controlled rapid cooling induces orderly molecular rearrangement and association of the polymer chains, forming a network structure with a composite colloidal network as the skeleton and physically separating and fixing the gelatinized starch molecular chains; f) Final stabilization of the high-pressure homogenization and emulsification system: The steamed and flash-cooled material is immediately pumped into a high-pressure homogenizer for multi-stage high-pressure homogenization to further break up and refine the primary starch-lipid complex, and distribute it evenly throughout the polymer network matrix in a submicron size, while promoting the interpenetration and entanglement between polymer chains to form a dense and uniform composite network structure; and g) Aseptic filling and controlled-rate cooling: The final product after high-pressure homogenization is aseptically filled while maintaining high temperature, and the sealed packaged product is programmed to undergo controlled-rate cooling to stabilize and lock the fine microstructure formed after high-pressure homogenization.

2. The preparation method according to claim 1, characterized in that The emulsified modified starch in step a) is octenyl succinate starch; the functional modified starch in step c) includes thickening modified starch, stringing modified starch and antifreeze modified starch; the thickening modified starch is acetylated distarch phosphate; the stringing modified starch is a cross-linked esterified starch with a high amylose content; the antifreeze modified starch is hydroxypropyl distarch phosphate; and the soybean lecithin in step a) is deoiled and purified powdered soybean lecithin.

3. The preparation method according to claim 2, characterized in that The degree of substitution of the octenyl succinate starch ester is 0.015 to 0.020, and the viscosity of its 5% concentration paste at 25°C is 50 to 150 mPa·s; the acetyl content of the acetylated distarch phosphate is 1.5% to 2.5%, and the gelatinization starting temperature is 60°C to 65°C; the amylose content of the cross-linked esterified starch with a high amylose content is greater than 50%; the hydroxypropyl substitution molar number of the hydroxypropyl distarch phosphate is 0.05 to 0.15, and the water separation rate of its paste after multiple freeze-thaw cycles is less than 5%; the phosphatidylcholine content of the powdered soy lecithin is not less than 30%.

4. The preparation method according to claim 1, characterized in that The hydrophilic colloid in step b) includes xanthan gum, carrageenan, gum arabic and locust bean gum; the sugar in step b) includes trehalose and glucose; the process water used in the method is purified water treated by reverse osmosis, and its conductivity is less than 5 microsiemens / cm.

5. The preparation method according to claim 4, characterized in that The xanthan gum is 80 mesh food grade xanthan gum, and the viscosity of its 1% concentration saline solution is not less than 1200 mPa·s; the carrageenan is κ-type refined carrageenan, and its gel strength at a concentration of 1.5% and in the presence of 0.2% potassium chloride is not less than 1000 g / cm2; the gum arabic is spray-dried Acacia gum, and its molecular weight distribution is between 250,000 and 600,000 Daltons; the locust bean gum is 100 mesh food grade locust bean gum, and the viscosity of its 1% concentration aqueous solution is between 2500 and 3500 mPa·s; the trehalose is α,α-1,1-glycosidic bond dihydrate trehalose with a purity greater than 99.0%; and the glucose is D-glucose monohydrate with a purity greater than 99.5%.

6. The preparation method according to claim 1, characterized in that The specific process parameters of step a), step b) and step c) are as follows: In step a), the first portion of process water accounts for 20% to 30% of the total water used; the high shear force is provided by an agitator with a rotation speed set at 3000 to 5000 rpm; the preset temperature is 65° C. to 75° C.; and the duration of the dispersion treatment is 15 to 25 minutes; In step b), the stirring and dispersing is carried out under medium speed stirring at a speed of 300 to 500 rpm for 30 to 40 minutes; the heating and heat preservation treatment is to raise the material temperature to 80° C. to 85° C. and keep it at this temperature for 20 minutes; In step c), the mixing is performed while maintaining a temperature of 80° C. to 85° C. for 15 to 20 minutes.

7. The preparation method according to claim 1, characterized in that The specific process parameters of step d), step e) and step f) are as follows: In step d), the ultra-high temperature instantaneous sterilization system heats the mixed material to 138° C. to 145° C. within 0.1 to 0.3 seconds and maintains this temperature for 3 to 5 seconds; In step e), the vacuum degree of the vacuum refining tank is set to -0.06 to -0.08 MPa, and the material temperature is instantly reduced to 85° C. to 95° C. by flash evaporation; In step f), the high-pressure homogenizer is a two-stage high-pressure homogenizer, wherein the first-stage homogenization pressure is set to 25 to 35 MPa, the second-stage homogenization pressure is set to 3 to 5 MPa, and the temperature of the material to be processed is maintained at 85°C to 90°C.

8. The preparation method according to claim 1, characterized in that The specific process parameters of step g) are as follows: the aseptic filling is carried out under the condition that the material temperature is not less than 80°C; the controlled rate cooling is carried out by using a multi-stage spray cooling channel to steadily reduce the product temperature from above 80°C to 25°C to 30°C within 30 to 40 minutes.

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