Crispy toast and preparation method thereof

Abstract

The invention relates to the technical field of food processing, and particularly discloses crisp toast and a preparation method thereof. The shortening toast is prepared from the following raw materials in parts by weight: 90 to 120 parts of flour, 13 to 17 parts of improved fresh yeast, 0.5 to 1.5 parts of a compound enzyme preparation, 10 to 15 parts of sugar, 0.5 to 1.5 parts of salt, 0.5 to 1.5 parts of an acidity regulator, 30 to 45 parts of water, 3 to 5 parts of eggs, 7 to 10 parts of dairy products and 7 to 10 parts of milk fat, the improved fresh yeast is prepared from the following raw materials: fresh yeast, pullulan, beta-cyclodextrin, an antioxidant and thermo-sensitive liposome. According to the preparation method of the crispy toast, the improved fresh yeast is adopted, the fermentation activity and the fermentation uniformity in the fermentation process after multiple times of refrigeration and unfreezing are guaranteed, the outer layer of the finished product is crispy and uniform, the inner layer is soft and porous, the consistency of the appearance and the taste of the crispy toast is guaranteed, and the shelf life is also prolonged.

Description

Technical Field

[0001] This application relates to the technical field of food processing, and more specifically, it relates to a flaky toast and its preparation method. Background Art

[0002] In the field of bread baking, flaky toast, as a baked food with both a crispy outer crust and a soft inner core, is deeply loved by consumers for its distinct layers, crispy taste, and convenient consumption. Fresh yeast, as a natural leavening agent, plays an important role in the preparation of flaky toast due to its low cost, high activity, strong fermenting power, and good flavor contribution ability. Compared with dry yeast, fresh yeast can promote dough fermentation more effectively, making the internal structure of flaky toast softer and the outer crust more crispy, thus enhancing the overall aesthetic appearance and taste flavor of flaky toast.

[0003] In the preparation process of flaky bread, in order to form uniform crispy layers, multiple freezing and thawing processes are usually involved to improve the dough structure, control the fermentation speed, and solidify the oil. However, during multiple freezing processes, the free water in fresh yeast cells forms ice crystals, which directly damages the structure of yeast cells, resulting in a decrease in yeast activity. After thawing, it is prone to cause out-of-control fermentation due to insufficient activity recovery, resulting in problems such as crispy layer breakage or finished toast collapse.

[0004] In addition, in the complex process of flaky toast, the activity of fresh yeast is also affected by other components in the dough such as sugar, salt, and acidic substances, resulting in uneven fermentation. This uneven fermentation also causes significant differences in the expansion of the crispy layers of the toast, affecting the appearance and taste consistency of flaky toast.

[0005] In view of the above related technologies, the inventor found that in the prior art, the method of increasing the amount of yeast is usually adopted to make up for the insufficient fermenting power of yeast caused by multiple freezing and thawing. However, an increase in the amount of yeast is likely to produce a yeast odor, and glutathione with reducing properties will also be produced during refrigeration, weakening the gluten network of the dough and affecting the appearance and taste flavor of flaky toast. Summary of the Invention

[0006] In order to enhance the fermentation vitality and fermentation stability of fresh yeast in the preparation process of flaky toast, and improve the aesthetic appearance and taste flavor of flaky toast, this application provides a flaky toast and its preparation method.

[0007] In the first aspect, this application provides a flaky toast, adopting the following technical solution: A flaky toast, by weight, the raw materials include 90-120 parts of flour, 13-17 parts of improved fresh yeast, 0.5-1.5 parts of compound enzyme preparation, 10-15 parts of sugar, 0.5-1.5 parts of salt, 0.5-1.5 parts of acidity regulator, 30-45 parts of water, 3-5 parts of eggs, 7-10 parts of dairy products and 7-10 parts of milk fat; the raw materials of the improved fresh yeast include fresh yeast, pullulan, β-cyclodextrin and thermosensitive liposome.

[0008] By adopting the above technical solution, the inventors found that by improving the fresh yeast into a microcapsule structure, the stress resistance of the fresh yeast can be effectively improved by means of wall material protection, the fermentation vitality of the fresh yeast can be guaranteed, and the product shelf life can be extended.

[0009] Using the improved fresh yeast ensures that in the complex process of preparing flaky toast, the fresh yeast can reduce the influence of low temperature and environmental osmotic pressure and maintain good activity after multiple freeze-storage thawings, promote the generation of fermentation reaction, ensure the uniformity of fermentation. Further, the compound enzyme preparation supplements the endogenous enzyme activity in the later stage of dough fermentation, synergizes with the improved fresh yeast, further promotes the refinement of the gluten network, enables the dough to form a uniform flaky layer and a soft and porous structure inside, and at the same time promotes the release of flavor aroma substances to enhance the flavor of the toast.

[0010] In addition, the combined use of dairy products and milk fat, the interaction between milk fat globule membrane protein and gluten protein, forms a fat and protein composite network, further improving the fluffiness and milk flavor of the toast, and ensuring the appearance and taste consistency of the flaky toast.

[0011] Optionally, the raw materials of the improved fresh yeast further include an antioxidant and sodium carboxymethylcellulose.

[0012] Optionally, by weight, the raw materials of the improved fresh yeast include 7-15 parts of fresh yeast, 5-7 parts of pullulan, 2-4 parts of β-cyclodextrin, 0.1-0.3 parts of antioxidant, 0.8-1.2 parts of sodium carboxymethylcellulose and 1-1.5 parts of thermosensitive liposome.

[0013] Experiments show that when pullulan polysaccharide is used as the wall material to prepare fresh yeast microcapsules, compared with fresh yeast microcapsules prepared with seaweed polysaccharide and chitosan as wall materials, the appearance of the final flaky toast is the most beautiful and the taste and flavor are the best, and the shelf life is also significantly extended compared with fresh yeast microcapsules prepared with other wall materials. This may be because the flexibility of the film formed by pullulan polysaccharide as the wall material is the best, the film brittleness of chitosan increases under freezing conditions, and the protective effect decreases. The linear structure of pullulan polysaccharide endows it with high crystallinity, and after being compounded with sodium carboxymethyl cellulose, it can form a dense film layer, tightly wrap the yeast cells, and inhibit the destruction of the cell structure caused by the formation of ice crystals from the free water inside the fresh yeast. The gel structure of seaweed polysaccharide may easily form large ice crystals directly piercing the yeast cells due to its relatively high water content during freezing.

[0014] Furthermore, the inventors found that using β-cyclodextrin to encapsulate antioxidants through hydrophobic cavities as an auxiliary wall material not only further enhances the mechanical strength and stability of the wall material and improves the protection effect on the core material, but especially, it can continuously release antioxidant substances during the thawing process, neutralize free radicals generated by freeze-thaw cycles, reduce oxidative stress damage to yeast cells, continuously promote the rapid recovery of the activity of fresh yeast, and at the same time ensure the taste and flavor of the flaky toast.

[0015] By adopting the above technical solution, the freeze resistance of fresh yeast is significantly improved, ensuring that the fresh yeast maintains its fermentation vitality after multiple freeze-storage and thawing, while ensuring the uniformity of the fermentation reaction, preventing fermentation out of control, reducing the phenomenon of dough structure collapse, flaky layer fracture caused by concentrated gas production in the initial stage of fermentation or insufficient activity in the later stage resulting in incomplete fermentation, and ensuring the appearance beauty and flavor of the flaky toast.

[0016] Optionally, the antioxidant is selected from any one of tea polyphenols, rosemary extract, resveratrol, vitamin E, vitamin C, ε-polylysine, and curcumin.

[0017] Optionally, the thermosensitive liposome is dipalmitoyl phosphatidylcholine and lecithin with a mass ratio of (1.5 - 3):1.

[0018] Optionally, the acidity regulator is selected from any one or a combination of two of vinegar powder and citric acid powder.

[0019] Optionally, the flour includes high-gluten wheat flour and low-gluten wheat flour with a mass ratio of (3 - 5):1.

[0020] Optionally, the dairy product includes milk powder and condensed milk.

[0021] Optionally, the complex enzyme preparation includes α-amylase, xylanase, cellulase, and glucose oxidase.

[0022] Second aspect, the present application provides a method for preparing puff toast, adopting the following technical solution: A method for preparing puff toast, comprising the following steps: S1: Dissolve β-cyclodextrin in water, add antioxidant after heating and stirring evenly, centrifuge and dry after stirring to obtain β-cyclodextrin inclusion antioxidant particles; dissolve pullulan in water, add β-cyclodextrin inclusion antioxidant particles after heating and stirring evenly, add sodium carboxymethylcellulose and thermosensitive liposomes after ultrasonic stirring, and stir evenly to obtain wall material liquid; add fresh yeast to the wall material liquid, stir at 500 - 1000 rpm for 10 - 15 min, and dry to obtain modified fresh yeast; S2: Weigh ingredients according to the proportion of each raw material, then knead, divide, relax, and press into blocks, and then quick-freeze at (-22 ± 2) °C for 20 - 25 min, and perform primary frozen storage at (-16 ± 5) °C for 12 - 16 h and then thaw to obtain the first dough; S3: Oil the first dough and then fold and roll it, then perform secondary frozen storage at (-16 ± 5) °C for 4 - 16 h and then warm up for shaping and thawing to obtain the second dough; S4: Let the second dough proof, bake, and cool to obtain the puff toast.

[0023] By adopting the above technical solution, first use β-cyclodextrin to wrap the antioxidant to form β-cyclodextrin inclusion antioxidant particles, and then mix with raw materials such as pullulan to form a multi-layer composite wall material, which promotes the dispersion uniformity and stability of the antioxidant in wall materials such as pullulan, has stronger bioavailability, ensures the survival rate and activity of fresh yeast during multiple freezing and thawing processes, and guarantees the fermentation uniformity and stability in the subsequent fermentation process. The combination of the secondary freezing and thawing process helps to promote the regulation of the gluten network, maintain the layered structure of the dough, ensure the puffing effect, effectively improve the layering of the puff toast, form a more uniform puff layer, and enhance the overall appearance beauty and taste flavor of the puff toast.

[0024] Optionally, the proofing conditions in step S4 are: temperature 34 - 36 °C, humidity 75 - 85%, and proofing time 0.5 - 1.5 h.

[0025] Optionally, the baking in step S4 is divided into three-stage baking: The upper fire temperature in the first stage is 180 - 190 °C, the lower fire temperature is 225 - 235 °C, and the time is 14 - 16 min; The upper fire temperature in the middle stage is 180 - 190 °C, the lower fire temperature is 215 - 225 °C, and the time is 10 - 12 min; The upper fire temperature in the last stage is 180 - 190 °C, the lower fire temperature is 235 - 245 °C, and the time is 14 - 16 min.

[0026] In summary, the present application has the following beneficial effects: 1. Since the present application uses pullulan as the main wall material and β-cyclodextrin-included antioxidant particles as the auxiliary wall material to prepare the improved fresh yeast with a microcapsule structure, the frost resistance of fresh yeast during the rapid freezing, multiple refrigerations and thawing processes in the complex process is significantly enhanced, and the reduction in activity caused by the influence of low temperature and environmental osmotic pressure during the preparation process is reduced, effectively ensuring the fermentation activity and fermentation uniformity during the thawing and proofing processes, reducing the phenomena of dough structure collapse, flaky layer fracture caused by concentrated gas production in the initial stage of fermentation, or insufficient fermentation caused by insufficient activity in the later stage, ensuring the appearance beauty and flavor of the flaky toast, and helping to extend the shelf life.

[0027] 2. In the present application, β-cyclodextrin is preferably used to include antioxidants through hydrophobic cavities as the auxiliary wall material, which can continuously release antioxidant substances during the thawing process to neutralize free radicals generated by the freeze-thaw cycle, continuously promote the rapid recovery of the activity of fresh yeast, reduce the oxidative stress damage to yeast cells and the weakening of the dough gluten network, and further improve the taste and flavor of the flaky toast.

[0028] 3. The method of the present application effectively regulates the gluten network by using the improved fresh yeast and performing the processes of quick-freezing the dough, secondary frozen storage and gradient proofing and baking, maintaining the layered structure of the dough, so that a uniform flaky layer is formed on the outer layer of the flaky toast, and the inner layer is soft and porous, ensuring the appearance and taste consistency of the flaky toast. Specific Embodiments

[0029] The following examples further illustrate the present application in detail.

[0030] Raw Materials Unless otherwise specified, the raw materials used in the preparation examples, examples and comparative examples of the present application are all commercially available food-grade products, all of which meet the requirements of GB 2760-2024. Specifically: Both the high-gluten wheat flour and the low-gluten wheat flour meet the requirements of GB 8607-1988 and GB 8608-1988; Fresh yeast, selected from SAF-Instant Fresh Yeast, 0746; Pullulan, selected from Jinan Dongxuan Biotechnology Co., Ltd., asfgasf; β-Cyclodextrin, selected from Shaanxi Ranken Biotechnology Co., Ltd., β-cyclodextrin; Dipalmitoyl phosphatidylcholine, CAS: 2797-68-4; Lecithin, selected from Shanxi Qingye Biotechnology Co., Ltd., QYSW-1024-154; Sodium carboxymethyl cellulose, selected from Henan Zhongxing Food Source Biotechnology Co., Ltd., zcj003; Vinegar powder, with a total acid content of 19 g / 100 g (calculated as acetic acid) and a moisture content of 4.8 g / 100 g; Tea polyphenols, selected from Shanxi Qingye Biotechnology Co., Ltd., QYSW - 1023 - 115; Rosemary extract, selected from Xi'an Zhuorui Biotechnology Co., Ltd., ZR - 3544; Resveratrol, selected from Shaanxi Junkang Biotechnology Co., Ltd., jk - bllc; α - amylase, xylanase, cellulase and glucose oxidase, all selected from Novozymes; Seaweed polysaccharide, which is sodium alginate, selected from Qingdao Mingyue Seaweed Group, food - grade sodium alginate, with the molecular formula (C6H7O6Na) n ; Chitosan, CAS: 9012 - 76 - 4.

[0031] Preparation examples of improved fresh yeast Preparation example 1 Improved fresh yeast, with the raw materials and dosages shown in Table 1. Among them, the antioxidant is tea polyphenols, and the thermosensitive liposome is a mixture of dipalmitoyl phosphatidylcholine and lecithin with a mass ratio of 2:1.

[0032] Table 1 Component / g Preparation Example 1 Preparation Example 2 Preparation Example 3 Preparation Example 4 Fresh yeast 10 7 12 15 Pullulan polysaccharide 5.8 5 6 7 β - Cyclodextrin 3 2 3 4 Antioxidant 0.2 0.1 0.2 0.3 Sodium carboxymethyl cellulose 1 0.8 1 1.2 Thermosensitive liposome 1 1.2 1.2 1.5 The preparation method of the above - mentioned improved fresh yeast includes the following steps: S1: Dissolve β - cyclodextrin in deionized water at a material - to - liquid ratio of 1:10, heat to 60 °C and stir evenly. Then add the antioxidant, stir, centrifuge, and obtain β - cyclodextrin - encapsulated antioxidant particles through spray drying; S2: Dissolve pullulan polysaccharide in deionized water at a material - to - liquid ratio of 1:10, heat to 45 °C and stir evenly. Then add the β - cyclodextrin - encapsulated antioxidant particles, stir ultrasonically at 40 kHz and 300 W for 10 min, and then add sodium carboxymethylcellulose and the thermosensitive liposome, and stir evenly to obtain the wall material solution; S3: Add fresh yeast to the wall material solution, stir at 1000 rpm for 10 min, and obtain the improved fresh yeast through spray drying.

[0033] Preparation example 2 Improved fresh yeast, different from Preparation example 1 in that the raw materials and dosages are shown in Table 1. Among them, the thermosensitive liposome is a mixture of dipalmitoyl phosphatidylcholine and lecithin with a mass ratio of 1.5:1; The preparation method of the above - mentioned improved fresh yeast includes the following steps: S1: Dissolve β - cyclodextrin in deionized water at a material - to - liquid ratio of 1:10, heat to 60 °C and stir evenly. Then add the antioxidant, stir, centrifuge, and obtain β - cyclodextrin - encapsulated antioxidant particles through spray drying; S2: Dissolve pullulan polysaccharide in deionized water at a material-liquid ratio of 1:10, heat to 45 °C and stir evenly, then add β-cyclodextrin to encapsulate antioxidant particles, and after ultrasonic stirring at 40 kHz and 300 W for 10 min, add sodium carboxymethylcellulose and thermosensitive liposomes, and stir evenly to obtain the wall material solution; S3: Add fresh yeast to the wall material solution, stir at 500 rpm for 15 min, and obtain the modified fresh yeast after spray drying.

[0034] Preparation Example 3 The modified fresh yeast, different from Preparation Example 1, is that the raw materials and dosages are as shown in Table 1, wherein the thermosensitive liposome is dipalmitoyl phosphatidylcholine and lecithin with a mass ratio of 3:1; The preparation method of the above-mentioned modified fresh yeast includes the following steps: S1: Dissolve β-cyclodextrin in deionized water at a material-liquid ratio of 1:10, heat to 60 °C and stir evenly, then add the antioxidant, stir, centrifuge, and obtain β-cyclodextrin-encapsulated antioxidant particles after spray drying; S2: Dissolve pullulan polysaccharide in deionized water at a material-liquid ratio of 1:10, heat to 45 °C and stir evenly, then add β-cyclodextrin-encapsulated antioxidant particles, and after ultrasonic stirring at 40 kHz and 300 W for 10 min, add sodium carboxymethylcellulose and thermosensitive liposomes, and stir evenly to obtain the wall material solution; S3: Add fresh yeast to the wall material solution, stir at 600 rpm for 15 min, and obtain the modified fresh yeast after spray drying.

[0035] Preparation Example 4 The modified fresh yeast, different from Preparation Example 1, is that the raw materials and dosages are as shown in Table 1, wherein the thermosensitive liposome is dipalmitoyl phosphatidylcholine and lecithin with a mass ratio of 2:1; The preparation method of the above-mentioned modified fresh yeast includes the following steps: S1: Dissolve β-cyclodextrin in deionized water at a material-liquid ratio of 1:10, heat to 60 °C and stir evenly, then add the antioxidant, stir, centrifuge, and obtain β-cyclodextrin-encapsulated antioxidant particles after spray drying; S2: Dissolve pullulan polysaccharide in deionized water at a material-liquid ratio of 1:10, heat to 45 °C and stir evenly, then add β-cyclodextrin-encapsulated antioxidant particles, and after ultrasonic stirring at 40 kHz and 300 W for 10 min, add sodium carboxymethylcellulose and thermosensitive liposomes, and stir evenly to obtain the wall material solution; S3: Add fresh yeast to the wall material solution, stir at 800 rpm for 12 min, and obtain the modified fresh yeast after spray drying.

[0036] Preparation Example 5 Improved fresh yeast, different from Preparation Example 1 in that the antioxidant in the raw materials is rosemary extract, and other steps are the same as those in Preparation Example 1.

[0037] Preparation Example 6 Improved fresh yeast, different from Preparation Example 1 in that the antioxidant in the raw materials is resveratrol, and other steps are the same as those in Preparation Example 1.

[0038] Preparation Example 7 Improved fresh yeast, different from Preparation Example 1 in that no antioxidant is added, and its preparation method includes the following steps: S1: Dissolve β-cyclodextrin in deionized water at a solid-liquid ratio of 1:10, heat to 60 °C and stir evenly to obtain the first solution; S2: Dissolve pullulan in deionized water at a solid-liquid ratio of 1:10, heat to 45 °C and stir evenly to obtain the second solution; S3: Mix the first solution and the second solution in equal volumes and stir evenly, then add sodium carboxymethylcellulose and thermosensitive liposomes, and stir evenly to obtain the wall material solution; S4: Add fresh yeast to the wall material solution, stir at 1000 rpm for 10 min, and obtain the improved fresh yeast after spray drying.

[0039] Preparation Example 8 Improved fresh yeast, different from Preparation Example 1 in that no sodium carboxymethylcellulose is added, and other steps are the same as those in Preparation Example 1.

[0040] Preparation Example 9 Improved fresh yeast, different from Preparation Example 1 in that the pullulan in the raw materials is replaced with an equal mass of seaweed polysaccharide, and other steps are the same as those in Preparation Example 1.

[0041] Preparation Example 10 Improved fresh yeast, different from Preparation Example 1 in that the pullulan in the raw materials is replaced with an equal mass of chitosan, and other steps are the same as those in Preparation Example 1.

[0042] Preparation Example 11 Improved fresh yeast, different from Preparation Example 1 in that the pullulan in the raw materials is replaced with a mixture of an equal mass of seaweed polysaccharide and chitosan, and the mass ratio of seaweed polysaccharide to chitosan is 2:1, and other steps are the same as those in Preparation Example 1. Example

[0043] Example 1 A puff toast, the raw materials and their dosages are shown in Table 2, wherein the improved fresh yeast is obtained from Preparation Example 1, the complex enzyme preparation is α-amylase, xylanase, cellulase and glucose oxidase with a mass ratio of 5:6:2:2, and the acidity regulator is vinegar powder.

[0044] Table 2 The preparation method of the above-mentioned flaky toast includes the following steps: S1: Weigh the ingredients according to the proportion of each raw material. After mixing the ingredients, knead the dough, divide it, relax it, and press it into blocks to obtain a preformed dough; S2: Place the preformed dough at (-22±2)°C for rapid freezing for 20 min, then store it at (-16±5)°C for the first freezing storage for 16 h, and then thaw it to a predetermined temperature of (-5.5±2)°C to obtain the first dough; S3: After oiling the first dough, fold and roll it, then store it at (-16±5)°C for the second freezing storage for 8 h, and then thaw it back to (-6.5±2)°C for shaping, and continue to thaw for 3 h to a predetermined temperature ≥15°C to obtain the second dough; S4: Let the second dough proof at 34°C and a humidity of 80% for 1 h. After proofing, cover it with a mold and bake it in a gradient manner. The upper fire temperature in the front stage is 180°C, the lower fire temperature is 230°C, and the time is 14 min; the upper fire temperature in the middle stage is 180°C, the lower fire temperature is 225°C, and the time is 10 min; the upper fire temperature in the latter stage is 180°C, the lower fire temperature is 235°C, and the time is 14 min. After baking, the product enters an automatic demolding machine. After turning out the toast, it flows into a cooling tower for cooling to obtain the finished product.

[0045] Example 2 A flaky toast, which is different from that in Example 1 in that the types and dosages of each raw material are shown in Table 2, wherein the improved fresh yeast is obtained from Preparation Example 2. The preparation method of the above-mentioned flaky toast includes the following steps: S1: Weigh the ingredients according to the proportion of each raw material. After mixing the ingredients, knead the dough, divide it, relax it, and press it into blocks to obtain a preformed dough; S2: Place the preformed dough at (-22±2)°C for rapid freezing for 25 min, then store it at (-16±5)°C for the first freezing storage for 12 h, and then thaw it to a predetermined temperature of (-5.5±2)°C to obtain the first dough; S3: After oiling the first dough, fold and roll it, then store it at (-16±5)°C for the second freezing storage for 16 h, and then thaw it back to (-6.5±2)°C for shaping, and continue to thaw for 3.5 h to a predetermined temperature ≥15°C to obtain the second dough; S4: Proof the second dough at 35°C and 75% humidity for 1.5 h. After proofing, cover the mold and perform gradient baking. The upper fire temperature in the first stage is 185°C, the lower fire temperature is 225°C, and the time is 16 min; the upper fire temperature in the middle stage is 185°C, the lower fire temperature is 215°C, and the time is 121 min; the upper fire temperature in the last stage is 185°C, the lower fire temperature is 235°C, and the time is 16 min. After baking, the product enters the automatic demolding machine. After the toast is turned out, it flows into the cooling tower for cooling to obtain the finished product.

[0046] Example 3 A flaky toast, different from Example 1 in that the raw materials and their dosages are shown in Table 2, and the improved fresh yeast is obtained from Preparation Example 3. The preparation method of the above flaky toast includes the following steps: S1: Weigh the ingredients according to the proportion of each raw material. After mixing the ingredients, knead, divide, relax, and press them to obtain a preformed dough; S2: Place the preformed dough at (-22±2)°C for rapid freezing for 20 min, then store it at (-16±5)°C for the first freezing storage for 14 h, and then thaw it to the predetermined temperature of (-5.5±2)°C to obtain the first dough. S3: After wrapping the first dough with oil, fold and roll it, then store it at (-16±5)°C for the second freezing storage for 4 h, and then thaw it back to (-6.5±2)°C for shaping, and continue to thaw for 2.5 h to the predetermined temperature ≥15°C to obtain the second dough. S4: Proof the second dough at 36°C and 85% humidity for 0.5 h. After proofing, cover the mold and perform gradient baking. The upper fire temperature in the first stage is 190°C, the lower fire temperature is 235°C, and the time is 15 min; the upper fire temperature in the middle stage is 190°C, the lower fire temperature is 225°C, and the time is 11 min; the upper fire temperature in the last stage is 190°C, the lower fire temperature is 245°C, and the time is 15 min. After baking, the product enters the automatic demolding machine. After the toast is turned out, it flows into the cooling tower for cooling to obtain the finished product.

[0047] Example 4 A flaky toast, different from Example 1 in that the raw materials and their dosages are shown in Table 2, and the improved fresh yeast is obtained from Preparation Example 4. The preparation method of the above flaky toast includes the following steps: S1: Weigh the ingredients according to the proportion of each raw material. After mixing the ingredients, knead, divide, relax, and press them to obtain a preformed dough; S2: Place the preformed dough at (-22±2)°C for rapid freezing for 25 min, then store it at (-16±5)°C for the first freezing storage for 15 h, and then thaw it to the predetermined temperature of (-5.5±2)°C to obtain the first dough. S3: After oiling and folding and rolling the first dough, it is secondarily frozen and stored at (-16 ± 5)°C for 10 h, then thawed and warmed to (-6.5 ± 2)°C for shaping, and further thawed for 3 h to a predetermined temperature ≥ 15°C to obtain the second dough; S4: The second dough is proofed at 35°C and 80% humidity for 1 h. After proofing, cover it with a mold and perform gradient baking. The front-stage top-fire temperature is 180°C, the bottom-fire temperature is 230°C, and the time is 15 min; the middle-stage top-fire temperature is 180°C, the bottom-fire temperature is 220°C, and the time is 10 min; the rear-stage top-fire temperature is 180°C, the bottom-fire temperature is 240°C, and the time is 15 min. After baking, the product enters an automatic demolding machine. After the toast is turned out, it flows into a cooling tower for cooling to obtain the product.

[0048] Example 5 A flaky toast, different from Example 1 in that the improved fresh yeast in the raw materials is obtained from Preparation Example 5, and the other steps are the same as those in Example 1.

[0049] Example 6 A flaky toast, different from Example 1 in that the improved fresh yeast in the raw materials is obtained from Preparation Example 6, and the other steps are the same as those in Example 1.

[0050] Example 7 A flaky toast, different from Example 1 in that the improved fresh yeast in the raw materials is obtained from Preparation Example 7, and the other steps are the same as those in Example 1.

[0051] Example 8 A flaky toast, different from Example 1 in that the improved fresh yeast in the raw materials is obtained from Preparation Example 8, and the other steps are the same as those in Example 1.

[0052] Comparative Example Comparative Example 1 A flaky toast, different from Example 1 in that the fresh yeast is not improved, and the improved fresh yeast in the raw materials is replaced with 6.7 g of fresh yeast, and the other steps are the same as those in Example 1.

[0053] Comparative Example 2 A flaky toast, different from Example 1 in that the microcapsule structure of the fresh yeast is not prepared, and the improved fresh yeast in the raw materials is replaced with a mixture of fresh yeast, pullulan polysaccharide, β-cyclodextrin, antioxidant, carboxymethyl cellulose sodium, and thermosensitive liposome with a mass ratio of 10:5.8:3:0.2:1:1 and an equal mass, wherein the thermosensitive liposome is a mixture of dipalmitoyl phosphatidylcholine and lecithin with a mass ratio of 2:1, and the other steps are the same as those in Example 1.

[0054] Comparative Example 3 A flaky toast, which is different from Example 1 in that the improved fresh yeast in the raw materials is obtained from Preparation Example 9, and other steps are the same as those in Example 1.

[0055] Comparative Example 4 A flaky toast, which is different from Example 1 in that the improved fresh yeast in the raw materials is obtained from Preparation Example 10, and other steps are the same as those in Example 1.

[0056] Comparative Example 5 A flaky toast, which is different from Example 1 in that the improved fresh yeast in the raw materials is obtained from Preparation Example 11, and other steps are the same as those in Example 1.

[0057] Performance detection test Test Example 1 Specific volume and hardness detection The hardness and specific volume of a flaky toast obtained by the preparation methods of Examples 1-8 and Comparative Examples 1-5 were detected after just being prepared, after being placed for 3 days, after being placed for 5 days, and after being placed for 7 days.

[0058] 1. The hardness was measured by using a TA.XT physical property tester to measure the hardness inside the flaky toast. The flaky toast was cut into uniform thin slices with a thickness of 15 mm along the vertical direction by a slicing machine. The middle two slices were taken, and a P36R probe was used for hardness testing. The specific parameters were: distance 20 mm, pre-test rate 2 mm / s, test rate 1 mm / s, post-test rate 1 mm / s, depression degree 50%, test force 0.05 N, time interval between two compressions 3 s. Each sample was repeatedly measured 5 times, the maximum and minimum values were excluded, and the average value was taken as the final result and recorded in Table 3.

[0059] 2. According to the relevant regulations of GB / T 20981-2021, the volume V (mL) of the flaky toast was measured by the rapeseed replacement method, and the mass M (g) of the flaky toast was measured by an electronic balance. The specific volume (mL / g) of the flaky toast = V / M. Each group of tests was carried out 3 times, and the average value of the 3 results was calculated as the final result and recorded in Table 3.

[0060] Table 3 It can be seen from the performance detection results of Examples 1-8 in Table 3 that the specific volume of a flaky toast of the present application is ≥5.1 mL / g, and the hardness is ≤336 g. This shows that during the preparation process of a flaky toast of the present application, the fresh yeast exhibits excellent fermentation activity, ferments sufficiently, promotes the expansion of the dough and the retention of gas, makes the inner layer of the finished toast soft and porous, enhances the gas-holding ability of the bread, makes the taste rich, soft, elastic and chewy, and ensures the appearance and taste consistency of the flaky toast.

[0061] According to the performance test results of Examples 1-6 and Comparative Examples 1-2, it can be seen that compared with the unmodified fresh yeast group, the puff pastry prepared by fermentation with modified fresh yeast has a higher specific volume and lower hardness, which indicates that the fresh yeast is affected by complex environmental factors during the processing technology, resulting in a decrease in yeast activity and uneven fermentation or insufficient fermentation. The present application uses pullulan as the main wall material and β-cyclodextrin-encapsulated antioxidant particles as auxiliary wall materials to prepare a modified fresh yeast with a microcapsule structure. Compared with directly mixing raw materials such as pullulan, β-cyclodextrin and antioxidants, it more effectively enhances the resistance of fresh yeast to the influence of low temperature and environmental osmotic pressure during complex process rapid freezing, multiple refrigeration and thawing, effectively ensures the fermentation activity and fermentation uniformity during the proofing process after thawing, prevents the problem of concentrated gas production in the early stage of fermentation leading to collapse of the dough structure, rupture of the crisp layer or insufficient fermentation due to insufficient activity in the later stage, and ensures the appearance and flavor of the puff pastry.

[0062] According to the performance test results of Example 1 and Comparative Examples 3-5, it can be seen that the present application uses pullulan as the main wall material for improving fresh yeast. Compared with the fresh yeast microcapsules prepared by using traditional seaweed polysaccharides and chitosan or a combination of the two as wall materials, the protection ability for fresh yeast is stronger, and the appearance and taste of the finished toast are better. This shows that pullulan has stronger flexibility, cold resistance and ability to inhibit free water from forming ice crystals to damage yeast cells when used as a wall material, ensuring that the fresh yeast maintains fermentation activity after multiple frozen storage and thawing while ensuring the uniformity of the fermentation reaction, preventing fermentation from getting out of control, ensuring the appearance and taste of the crispy toast, and the toast has a stronger gas holding capacity.

[0063] It can be seen from the performance test results of Example 1 and Example 7 that the use of β-cyclodextrin as an auxiliary wall material by enclosing an antioxidant through a hydrophobic cavity not only helps to enhance the mechanical strength and stability of the wall material and improve the protection effect on fresh yeast, but also can continuously release antioxidant substances during the thawing process, neutralize free radicals generated by freezing and thawing cycles, reduce oxidative stress damage to yeast cells, and continuously promote the rapid recovery of the activity of fresh yeast, thereby ensuring the taste and flavor of the puff pastry and extending the shelf life of the product.

[0064] According to the performance test results of Example 1 and Example 8, it can be seen that when pullulan is used as the wall material and sodium carboxymethyl cellulose is added as an auxiliary, the straight chain structure of pullulan gives it a high degree of crystallinity. After being compounded with sodium carboxymethyl cellulose, it can form a dense membrane layer that tightly wraps the yeast cells, and can enhance the inhibition of ice crystals formed by free water in fresh yeast cells to damage the cell structure.

[0065] Test Example 2 Sensory Evaluation 10 professionally trained tasters were selected to conduct sensory evaluation on the crispy toasts obtained by the preparation methods of Examples 1-8 and Comparative Examples 1-5, respectively. The average of the scores given by the 10 tasters was taken as the final result and recorded in Table 5. Table 4 is the scoring standard for the sensory evaluation.

[0066] Table 4 Table 5 Group Appearance / score Flavor / score Taste / score Total score / score Example 1 28 19 29 76 Example 2 27 18 28 73 Example 3 27 19 28 74 Example 4 28 18 28 74 Example 5 28 18 26 72 Example 6 27 17 27 71 Example 7 22 12 23 57 Example 8 25 17 25 67 Comparative Example 1 13 14 17 44 Comparative Example 2 19 14 19 52 Comparative Example 3 21 16 21 58 Comparative Example 4 22 16 22 60 Comparative Example 5 22 17 22 61 According to the sensory evaluation test result data of Examples 1-6 in Table 5, it can be seen that the puff pastry toast of the present application has uniform crisp layers, complete and full structure, soft taste and rich chewing layers, and can be loved by most consumers.

[0067] According to the performance test results of Example 1 and Comparative Examples 1-5, it can be seen that the puff pastry prepared by using the improved fresh yeast with a microcapsule structure prepared using pullulan as the main wall material and β-cyclodextrin-encapsulated antioxidant particles as the auxiliary wall material significantly improves the environmental resistance of fresh yeast in a complex process environment, effectively reduces the phenomenon of concentrated gas production in the early stage of fermentation leading to dough structure collapse, crisp layer breakage, or insufficient fermentation due to insufficient activity in the later stage, thereby ensuring the aesthetic appearance and flavor of the puff pastry.

[0068] According to the performance test results of Example 1 and Example 7, it can be seen that the appearance, taste and flavor of the prepared crispy toast in the group without using antioxidants are significantly reduced. This is because β-cyclodextrin not only protects the antioxidant itself by enclosing the antioxidant in the hydrophobic cavity as an auxiliary wall material, but also continuously releases antioxidant substances during the thawing process to neutralize the free radicals generated by the freezing and thawing cycle, continuously promote the rapid recovery of the activity of fresh yeast, reduce the oxidative stress damage to yeast cells and the weakening of the dough gluten network, and improve the taste and flavor of the crispy toast.

[0069] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A flaky toast, characterized in that, By weight, the raw materials include 90 - 120 parts of flour, 13 - 17 parts of improved fresh yeast, 0.5 - 1.5 parts of compound enzyme preparation, 10 - 15 parts of sugar, 0.5 - 1.5 parts of salt, 0.5 - 1.5 parts of acidity regulator, 30 - 45 parts of water, 3 - 5 parts of eggs, 7 - 10 parts of dairy products and 7 - 10 parts of milk fat; the raw materials of the improved fresh yeast include fresh yeast, pullulan, β - cyclodextrin, antioxidant and thermosensitive liposome.

2. The flaky toast according to claim 1, wherein, The raw materials of the improved fresh yeast further include antioxidant and sodium carboxymethyl cellulose.

3. The flaky toast according to claim 2, wherein, By weight, the raw materials of the improved fresh yeast include 7 - 15 parts of fresh yeast, 5 - 7 parts of pullulan, 2 - 4 parts of β - cyclodextrin, 0.1 - 0.3 parts of antioxidant, 0.8 - 1.2 parts of sodium carboxymethyl cellulose and 1 - 1.5 parts of thermosensitive liposome.

4. The flaky toast according to claim 2, characterized in that, The antioxidant is selected from any one of tea polyphenols, rosemary extract, resveratrol, vitamin E, vitamin C, ε - polylysine and curcumin.

5. The flaky toast according to claim 1, characterized in that, The thermosensitive liposome is dipalmitoyl phosphatidylcholine and lecithin with a mass ratio of (1.5 - 3):

1.

6. The flaky toast according to claim 1, wherein, The flour includes high - gluten wheat flour and low - gluten wheat flour with a mass ratio of (3 - 5):

1.

7. A method for preparing a flaky toast according to any one of claims 1-6, characterized in that, It includes the following steps: S1: Dissolve β - cyclodextrin in water, heat and stir evenly, then add antioxidant, stir, centrifuge and dry to obtain β - cyclodextrin - encapsulated antioxidant particles; dissolve pullulan in water, heat and stir evenly, then add β - cyclodextrin - encapsulated antioxidant particles, stir ultrasonically, then add sodium carboxymethyl cellulose and thermosensitive liposome, and stir evenly to obtain wall material liquid; add fresh yeast to the wall material liquid, stir at 500 - 1000 rpm for 10 - 15 min, and dry to obtain improved fresh yeast; S2: Weigh the raw materials according to the proportion, then knead the dough, divide, relax, press the dough, and quick - freeze it at (-22 ± 2)°C for 20 - 25 min, and freeze - store it at (-16 ± 5)°C for 12 - 16 h and then thaw to obtain the first dough; S3: Oil the first dough, then fold and roll it, and then freeze - store it at (-16 ± 5)°C for 4 - 16 h, then warm it up, shape it and thaw it to obtain the second dough; S4: Let the second dough proof, bake and cool to obtain the product.

8. The preparation method of the flaky toast according to claim 7, characterized in that, The proofing conditions in step S4 are: temperature 34 - 36°C, humidity 75 - 85%, and proofing time 0.5 - 1.5 h.

9. The preparation method of the flaky toast according to claim 7, characterized in that, The baking in step S4 is divided into three - stage baking: In the first stage, the upper - fire temperature is 180 - 190°C, the lower - fire temperature is 225 - 235°C, and the time is 14 - 16 min; In the middle stage, the upper - fire temperature is 180 - 190°C, the lower - fire temperature is 215 - 225°C, and the time is 10 - 12 min; In the last stage, the upper - fire temperature is 180 - 190°C, the lower - fire temperature is 235 - 245°C, and the time is 14 - 16 min.

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