A method for preparing pretzel bread

Abstract

A method for preparing pretzel bread, comprising the following ingredients: high-gluten flour, water, low-gluten flour, fresh yeast, salt, oil, pure milk, whole milk powder, baking powder, sugar alcohol, sugar substitute, food preservative, and glycerin. The method omits the "freezing setting" step, optimizing the process into a continuous "shaping-lye sprinkling-cutting-oil spraying-baking" flow. This application optimizes the formula and preparation method of pretzel bread. By omitting the "freezing setting" step in existing methods, the resulting pretzel bread has a more fluffy and soft texture, a moist mouthfeel, effectively delays aging and hardening, and improves excessive chewiness. Furthermore, the use of a combination of sugar alcohol and glycerin to reduce water activity, combined with surface spraying of polylysine solution for antibacterial purposes, successfully extends the product's shelf life significantly from the traditional 3-5 days to over 90 days through this dual preservation strategy of "internal and external integration."

Description

Technical Field

[0001] This invention belongs to the field of pretzel bread preparation technology, specifically relating to a method for preparing pretzel bread. Background Technology

[0002] Pretzels are breads that are soaked or brushed with a dilute sodium hydroxide (NaOH) solution before baking. This unique "pretzel bath" process is how they get their name. They are loved for their distinctive flavor and deep brown, glossy crust. However, traditional German pretzels have the following significant drawbacks in their production and sales: 1. Formula defects: Traditional formulas are usually health-oriented with "0 sugar and low oil", but this results in poor product moisturizing properties, dense internal structure and insufficient fluffiness, which accelerates the product aging and hardening and shortens the shelf life. 2. Short shelf life: Because bread needs to be soaked in strong alkaline water (such as sodium hydroxide solution) before baking, the pH value of the product surface is extremely high, and the internal water activity is difficult to control. This environment provides favorable conditions for the growth of microorganisms (especially molds), which makes the shelf life of traditional alkaline bread usually only 3-5 days. It is very easy to become moldy, which limits its sales radius and channels. 3. Production Process Defects: Traditional processes typically involve freezing the dough after shaping, followed by lye treatment, and finally baking. This process has the following problems: ① Poor product quality: Freezing easily causes ice crystals inside the dough, damaging the gluten structure, resulting in a product that ages quickly, has a dry and hard texture, is overly chewy, and lacks a fluffy and soft internal structure; ② Poor process continuity: The freezing process is time-consuming, interrupting production continuity and failing to meet the high-efficiency, continuous production requirements of modern industrial production lines, resulting in low capacity; ③ Reliance on manual labor and low automation: The lye treatment process is the core step determining the color and flavor of the finished product. Currently, lye treatment mainly uses manual brushing or overall soaking. Manual brushing is inefficient, and it is difficult to ensure the uniformity of lye distribution. Prolonged contact with lye also poses safety hazards to operators. While overall soaking can achieve full coverage of the dough surface, it requires a large amount of lye. Prolonged soaking can easily cause the surface to soften, deform, or even loosen, affecting subsequent baking, shaping, and the appearance quality of the finished product. Therefore, there is an urgent need in this field for a new technological solution that can comprehensively solve the above problems and achieve high-quality, long-shelf-life, and industrialized automated production of pretzel bread. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing lye bread.

[0004] The present invention adopts the following technical solution: A method for preparing pretzel bread, wherein the pretzel bread comprises the following ingredients in parts by weight: 100 parts high-gluten flour, 34-36 parts water, 10-15 parts low-gluten flour, 3-4 parts fresh yeast, 1.5-2.5 parts salt, 5-10 parts oil, 10-15 parts pure milk, 3-5 parts whole milk powder, 0.05-0.2 parts baking powder, 5-15 parts sugar alcohol, 5-10 parts sugar substitute, 0.3-0.6 parts food preservative, and 0.5-1.5 parts glycerin; Its preparation method specifically includes the following steps: Step 1: Put the weighed pretzel bread ingredients into a horizontal mixer and mix until the dough surface is smooth to obtain the basic dough. Then, send the shaped basic dough into a dough forming machine to obtain multiple pretzel doughs of uniform size. Step 2: The obtained alkaline dough is transported to the alkaline spraying device. The alkaline solution is sprayed onto the top surface of the alkaline dough and the bottom of the alkaline dough is immersed at the same time. The alkaline solution treatment time is controlled at 15-20 seconds. Step 3: The alkaline dough that has been treated with alkali solution is sent to the proofing device for proofing, and then the top surface of the proofed alkaline dough is cut using the cutting device. Step 4: After the alkaline dough has been cut, it enters the oil spraying device so that the oil is evenly sprayed on the surface of the alkaline dough. Step 5: After the oil spraying treatment, the alkaline dough is put into the baking device for baking. After cooling, polylysine solution is sprayed on the surface of the shaped bread to obtain the alkaline bread. The polylysine mixture is obtained by mixing 6 grams of polylysine with 1000 grams of 75% alcohol.

[0005] Furthermore, in step 3, the conditions for proofing the alkaline dough are as follows: relative humidity of 60-65%, temperature of 37±1℃, and proofing time of 20-30 minutes.

[0006] Furthermore, in step 5, when the baking device bakes the lye dough, the top heat of zone one is 120℃ and the bottom heat is 100℃; the top heat of zone two is 145℃ and the bottom heat is 110℃; and the temperature of zone three is 210℃, with a total baking time of 22-30 minutes. The temperature of the cooling zone is 22-26℃ and the humidity is 55±5%, so that the finished bread cools to a center temperature of 35±1℃.

[0007] Furthermore, the diameter of the alkaline dough is 15±0.5cm.

[0008] Furthermore, in step 3, the length of the incision is 5-5.5cm, the depth is 2±0.3cm, and the width is 1±0.3cm.

[0009] Furthermore, in step 1, when mixing the bread ingredients, proceed as follows: First stage: Stir at 60 rpm for 240 seconds; Second stage: Increase speed to 75 rpm, stir for 800 seconds until the stage of lifting up, then maintain the speed and continue stirring for another 500 seconds; Third stage: Increase the speed to 80 rpm, mix for 60 seconds, then open the lid and scrape the oil from the edges into the dough; Fourth stage: Control the speed to 75 rpm and stir for 120 seconds until the gluten is developed. At this time, the surface of the basic dough is smooth, the oil is fully absorbed, and the temperature of the basic dough is controlled at 27±1℃. After mixing, let it rest for 10-15 minutes before putting it into the dough forming machine.

[0010] Furthermore, step 6 involves packaging the obtained pretzel bread, which requires the addition of nitrogen gas and the inclusion of a dual-effect deoxidizer.

[0011] Furthermore, the food preservative is composed of calcium propionate and potassium sorbate in a mass ratio of 1.7:1.

[0012] Furthermore, the sugar alcohol is selected from one or more of sorbitol and maltitol; the fat is selected from one or more of butter and shortening; and the sugar substitute is selected from one or more of maltitol and erythritol.

[0013] Furthermore, the alkali spraying device includes a conveyor frame, a mesh conveyor belt mounted on the conveyor frame, a drive mechanism for driving the mesh conveyor belt, an alkali spraying mechanism for spraying alkali onto the top surface of the alkali dough, an alkali soaking mechanism for soaking the bottom of the alkali dough in alkali, and a supply mechanism for supplying alkali to the alkali spraying mechanism and the alkali soaking mechanism. The alkali soaking mechanism soaks the bottom of the alkali dough conveyed on the conveying mechanism with alkali solution. It includes an alkali tank supported on the conveyor frame and located below the alkali dough, multiple inlet pipes extending into the alkali tank, and multiple outlet holes spaced apart on the inlet pipes. The outlet holes are arranged opposite to the bottom of the alkali dough and their openings face upward, so that the alkali solution flowing out of the outlet holes gushes upward to form a fountain phenomenon. The gushes out alkali solution can overflow the mesh conveyor belt and contact the bottom of the alkali dough. During alkali treatment, the alkali spraying mechanism sprays alkali onto the top surface of the alkali dough from above, while the alkali impregnation mechanism gushes out alkali through its inlet pipe and upward-facing outlet, creating a fountain-like phenomenon. The gushes-out alkali overflows the mesh conveyor belt and comes into contact with the bottom of the alkali dough, thus achieving simultaneous top spraying and bottom impregnation.

[0014] As can be seen from the above description of the present invention, compared with the prior art, the beneficial effects of the present invention are as follows: The present application optimizes the formula and preparation method of pretzel bread. By omitting the "freezing and shaping" in the existing preparation method, the resulting pretzel bread has a more fluffy and soft texture, a moist mouthfeel, effectively delays aging and hardening, and improves excessive chewiness. Furthermore, by using a combination of sugar alcohol and glycerin to reduce water activity, and by spraying polylysine solution on the surface for antibacterial purposes, this "internal and external" dual preservation strategy successfully extends the product shelf life significantly from the traditional 3-5 days to more than 90 days. At the same time, the method steps omit the "freezing and shaping" and optimize the method into a continuous "shaping-alkali rinsing-cutting-oil spraying-baking" process, which greatly shortens the production cycle, improves equipment utilization and capacity, and perfectly meets the requirements of modern food industrial production lines. Attached Figure Description

[0015] Figure 1 Schematic diagram of the alkaline water spraying device Figure 1 ; Figure 2 Schematic diagram of the alkaline water spraying device Figure 2 ; Figure 3 This is a schematic diagram of the conveying mechanism; Figure 4 Schematic diagram of the structure of the alkali spraying mechanism and the alkali impregnation mechanism Figure 1 ; Figure 5 Schematic diagram of the structure of the alkali spraying mechanism and the alkali impregnation mechanism Figure 2 ; Figure 6 This is a schematic diagram of the fuel injection device. Figure 7 This is a schematic diagram of the conveying mechanism; Figure 8 This is a schematic diagram of the first fuel injection mechanism; Figure 9 This is a partial structural diagram of the first fuel injection mechanism; Figure 10 This is a schematic diagram of the swinging vertical rod. Figure 11 This is a schematic diagram of the swing crossbar. Figure 12 for Figure 11 A partial structural diagram; In the diagram, 1. Alkali spraying device; 2. Oil spraying device; 11. Conveyor frame; 12. Mesh conveyor belt; 13. Drive mechanism; 131. Drive motor; 132. Drive roller; 133. Driven roller; 134. First positioning roller; 135. Second positioning roller; 136. First transmission assembly; 1361. First drive gear; 1362. First driven gear; 1363. First transmission toothed belt; 137. Second transmission assembly; 1371. Second drive gear; 1372. Second driven gear; 13 73. Second transmission toothed belt; 138. Third transmission assembly; 14. Alkali spraying mechanism; 141. Main spray pipe; 142. Spray branch pipe; 143. Spray head; 144. Spray switch valve; 15. Alkali impregnation mechanism; 151. Alkali tank; 1511. First tank body; 1512. Second tank body; 1513. Return pipe; 152. Inlet pipe; 1521. Connecting section; 1522. Extension section; 1523. Main inlet section; 153. Outlet hole; 154. Inlet switch valve; 16. Liquid supply Mechanism; 161. Alkali tank; 162. Supply pipe; 163. Pump; 164. Circulation pipe; 17. Waste liquid tank; 21. Conveying mechanism; 211. Frame; 212. Dough conveyor belt; 22. First oil spraying mechanism; 221. Oil spraying base; 222. Swing frame; 2221. Swing base; 2222. Swing vertical rod; 22221. Swing part; 22222. Extension rod; 2223. Swing horizontal rod; 22231. Connecting block; 22232. Perforation; 2224. Fixing component; 22 241. Fixing screw hole; 22242. Fixing bolt; 2225. Swing shaft; 223. Injector; 224. Oil inlet assembly; 2241. Mounting block; 2242. Main oil inlet pipe; 2243. Branch oil inlet pipe; 2244. Oil delivery pipe; 225. Swing assembly; 2251. Swing motor; 2252. Reducer; 2253. Coupling; 226. Connecting rod; 23. Image detection mechanism; 231. Detection frame; 232. Detection block; 233. Detection camera; 24. Second oil injection mechanism. Detailed Implementation

[0016] The present invention will be further described below through specific embodiments.

[0017] A type of pretzel bread comprises the following ingredients in parts by weight: 100 parts high-gluten flour, 34-36 parts water, 10-15 parts low-gluten flour, 3-4 parts fresh yeast, 1.5-2.5 parts salt, 5-10 parts fat, 10-15 parts pure milk, 3-5 parts whole milk powder, 0.05-0.2 parts baking powder, 5-15 parts sugar alcohol, 5-10 parts sugar substitute, 0.3-0.6 parts food preservative, and 0.5-1.5 parts glycerin; wherein the food preservative is composed of calcium propionate and potassium sorbate in a mass ratio of 1.7:1; the sugar alcohol is selected from one or more of sorbitol and maltitol; the fat is selected from one or more of butter and shortening; and the sugar substitute is selected from one or more of maltitol and erythritol.

[0018] Its preparation method specifically includes the following steps: Step 1: Put the weighed ingredients for the lye bread into a horizontal mixer and mix until the dough surface is smooth to obtain the basic dough. Then, put the shaped basic dough into a dough forming machine to obtain multiple lye doughs of uniform size, wherein the diameter of the lye dough is 15±0.5cm. Step 2: The obtained alkaline dough is transported to the alkaline spraying device 1. The alkaline solution is sprayed onto the top surface of the alkaline dough and the bottom of the alkaline dough is immersed at the same time. The alkaline solution treatment time is controlled at 15-20 seconds. The alkaline solution used is a 4% sodium hydroxide solution. Step 3: The alkaline dough that has been treated with alkali solution is sent to the proofing device for proofing, and then the top surface of the proofed alkaline dough is cut using the cutting device. Step 4: The alkaline dough that has been cut is put into the oil spraying device 2, so that the oil is evenly sprayed on the surface of the alkaline dough. Step 5: After the oil spraying treatment, the alkaline dough is put into the baking device for baking. After cooling, polylysine solution is sprayed on the surface of the shaped bread to obtain the alkaline bread. The polylysine mixture is obtained by mixing 6 grams of polylysine with 1000 grams of 75% alcohol. Step 6: Package the obtained pretzel bread. Nitrogen gas and a double-effect oxygen absorber are required during packaging.

[0019] Specifically, in step 1, when mixing the bread ingredients, follow these steps: First stage: Stir at 60 rpm for 240 seconds; Second stage: Increase speed to 75 rpm, stir for 800 seconds until the stage of lifting up, then maintain the speed and continue stirring for another 500 seconds; Third stage: Increase the speed to 80 rpm, mix for 60 seconds, then open the lid and scrape the oil from the edges into the dough; Fourth stage: Control the speed to 75 rpm and stir for 120 seconds until the gluten is developed. At this time, the surface of the basic dough is smooth, the oil is fully absorbed, and the temperature of the basic dough is controlled at 27±1℃. After mixing, let it rest for 10-15 minutes before putting it into the dough forming machine.

[0020] In step 3, the conditions for proofing the alkaline dough are as follows: relative humidity of 60-65%, temperature of 37±1℃, and proofing time of 20-30 minutes; and when making the cuts, the length of the cuts is 5-5.5cm, the depth is 2±0.3cm, and the width is 1±0.3cm.

[0021] In step 5, when the baking device bakes the lye dough, the top heat of zone one is 120℃ and the bottom heat is 100℃; the top heat of zone two is 145℃ and the bottom heat is 110℃; and the temperature of zone three is 210℃, with a total baking time of 22-30 minutes. The temperature of the cooling zone is 22-26℃ and the humidity is 55±5%, so that the finished bread cools to a center temperature of 35±1℃.

[0022] In the above embodiments, reference is made to Figures 1 to 5 As shown, the alkaline water spraying device 1 includes a conveyor frame 11, a mesh conveyor belt 12 mounted on the conveyor frame 11, a drive mechanism 13 for driving the mesh conveyor belt 12, an alkaline water spraying mechanism 14 for spraying alkaline solution onto the top surface of the alkaline dough, an alkaline water soaking mechanism 15 for soaking the bottom of the alkaline dough in alkaline solution, and a supply mechanism 16 for supplying alkaline solution to the alkaline water spraying mechanism 14 and the alkaline water soaking mechanism 15. The mesh conveyor belt 12 is made of corrosion-resistant stainless steel or food-grade plastic mesh conveyor belt, and its mesh aperture is preferably 10-20mm so that the alkaline solution can pass through the mesh conveyor belt 12 smoothly and contact the bottom of the alkaline dough.

[0023] The drive mechanism 13 includes a drive motor 131, a drive roller 132 rotatably mounted on the conveyor frame 11 and connected to the output shaft of the drive motor 131, a driven roller 133 rotatably mounted on the conveyor frame 11 opposite to the drive roller 132, a first positioning roller 134 disposed on one side of the drive roller 132, a second positioning roller 135 disposed on one side of the driven roller 133, a first transmission assembly 136 disposed between the drive roller 132 and the driven roller 133, a second transmission assembly 137 disposed between the drive roller 132 and the first positioning roller 134, and a driven roller 133 disposed on the driven roller 133. A third transmission assembly 138 is provided between the second positioning roller 135 and the first positioning roller 134. The first positioning roller 134 and the second positioning roller 135 are respectively positioned above the driving roller 132 and the driven roller 133. The mesh conveyor belt 12 is arranged around the driving roller 132, the driven roller 133, the first positioning roller 134 and the second positioning roller 135. By setting the first positioning roller 134 and the second positioning roller 135, the wrap angle between the mesh conveyor belt 12 and the driving roller 132 and the driven roller 133 can be increased to prevent the conveyor belt from slipping and to keep the mesh conveyor belt 12 stable when carrying dough.

[0024] In this embodiment, the first transmission component 136 includes a first driving gear 1361 disposed at the end of the driving roller 132, a first driven gear 1362 disposed at the end of the driven roller 133 opposite to the first driving gear 1361, and a first transmission toothed belt 1363 meshing between the first driving gear 1361 and the first driven gear 1362. During alkaline water spraying, the drive motor 131 drives the driving roller 132 to rotate, and the driving roller 132 drives the driven roller 133 to rotate synchronously through the first transmission component 136. In conjunction with the second transmission component 137 and the third transmission component 138, the first positioning roller 134 and the second positioning roller 135 rotate synchronously, thereby driving the mesh conveyor belt 12 to run and realize the conveying of alkaline water dough.

[0025] In this embodiment, the second transmission assembly 137 includes a second driving gear 1371 disposed at the end of the driving roller 132, a second driven gear 1372 disposed at the end of the first positioning roller 134 opposite to the second driving gear 1371, and a second transmission toothed belt 1373 meshing between the second driving gear 1371 and the second driven gear 1372. The second driving gear 1371 and the first driving gear 1361 are coaxially arranged. When the driving roller 132 rotates, it drives the first positioning roller 134 to rotate synchronously via the second transmission assembly 137. Since the first positioning roller 134 is located above the driving roller 132, its rotation helps the mesh conveyor belt 12 smoothly transition to the upper plane after passing around the driving roller 132, reducing friction between the mesh conveyor belt 12 and the conveyor frame 11.

[0026] In this embodiment, the third transmission component 138 has the same structure as the second transmission component 137, and will not be described further here.

[0027] The alkali spraying mechanism 14 sprays alkali solution onto the top surface of the alkali dough conveyed on the mesh conveyor belt 12. It includes a main spray pipe 141, multiple spray branch pipes 142 connected to the main spray pipe 141, and multiple spray heads 143 spaced apart on each spray branch pipe 142. The spray branch pipes 142 are located above the alkali dough and are spaced apart along the conveying direction of the alkali dough. Specifically, the spacing between adjacent spray branch pipes 142 can be adjusted according to the size of the alkali dough and the conveying speed to ensure that the alkali solution evenly covers the top surface of the dough. Furthermore, the spray heads 143 are trumpet-shaped spray heads, and the spray heads 143 are commonly used components in the field of liquid spraying technology; their specific structure and working principle will not be further elaborated here.

[0028] The alkali soaking mechanism 15 soaks the bottom of the alkali dough conveyed on the mesh conveyor belt 12 with alkali solution. It includes an alkali tank 151 supported on the conveyor frame 11 and located below the alkali dough, multiple inlet pipes 152 extending into the alkali tank 151, and multiple outlet holes 153 spaced apart on the inlet pipes 152. The outlet holes 153 are positioned opposite the bottom of the alkali dough, with their openings facing upwards, causing the alkali solution flowing from the outlet holes 153 to gush upwards, forming a fountain effect. The gushing alkali solution can overflow the mesh conveyor belt 12 and contact the bottom of the alkali dough. During operation, the flow rate and pressure of the inlet pipes 152 are controlled to maintain the height of the alkali fountain between 5-30 mm, ensuring that the bottom of the alkali dough is fully in contact with the alkali solution without causing the dough to float or shift due to excessive height.

[0029] In this embodiment, the alkali solution tank 151 includes a first tank body 1511, a second tank body 1512 disposed within the first tank body 1511, and a return pipe 1513 connecting the first tank body 1511 and the supply mechanism 16. The second tank body 1512 is higher than the first tank body 1511, allowing the alkali solution flowing upwards from the outlet 153 to overflow into the first tank body 1511. By defining the structural composition of the alkali solution tank 151, this double-layered tank structure effectively maintains a relatively stable liquid level in the second tank body 1512, ensuring the continuity and uniformity of the gushing phenomenon. Furthermore, the alkali solution overflowing into the first tank body 1511 returns to the supply mechanism 16 via the return pipe 1513, achieving alkali solution recycling and reducing alkali solution consumption. Specifically, in practical applications, the first tank body 1511 and the second tank body 1512 can be integrally formed or separately welded; furthermore, a drain outlet can be provided at the bottom of the second tank body 1512 for easy cleaning and maintenance.

[0030] In this embodiment, the inlet pipe 152 includes an upwardly extending connecting section 1521 connected to the supply mechanism 16, an extension section 1522 connected to the upper end of the connecting section 1521 and extending downward into the second tank 1512, and a main inlet section 1523 connected to the lower end of the extension section 1522 and located in the second tank 1512. Multiple outlet holes 153 are provided on the main inlet section 1523. By defining the structure of the inlet pipe 152, the alkaline solution in the inlet pipe 152 first flows upward and then downward, effectively mitigating supply pressure fluctuations and making the pressure of the alkaline solution entering the main inlet section 1523 more stable, thereby forming a stable bubbling effect. Specifically, the main inlet section 1523 is horizontally arranged in the second tank 1512.

[0031] In this embodiment, the inlet pipe 152 also includes an inlet switch valve 154 disposed on the connecting section 1521. The inlet switch valve 154 is used to control the flow rate of alkali solution entering the relative inlet pipe 152. During operation, the opening degree of each inlet switch valve 154 can be adjusted according to the distribution position of the alkali dough on the grid conveyor belt 12 to achieve zoned control of the gushing intensity and avoid waste of alkali solution.

[0032] In this embodiment, a spray switch valve 144 is provided on the spray main pipe 141, wherein the spray switch valve 144 is used to control the flow rate of alkali solution entering the spray main pipe 141. By providing a spray switch valve 144 on the spray main pipe 141, on the one hand, the top spray volume can be flexibly adjusted according to the process requirements of different lye doughs, realizing precise control of alkali solution supply and avoiding waste; on the other hand, it is convenient to quickly cut off the alkali solution supply during equipment cleaning or maintenance, improving operational convenience. At the same time, the spray switch valve 144 and the liquid inlet switch valve 154 on the liquid inlet pipe 152 are independent of each other, so that the top spray and the bottom spring soaking can be adjusted separately, achieving the optimal balance of the overall alkali solution adsorption of the dough, thereby effectively improving the color uniformity and flavor quality of the lye bread after baking.

[0033] The supply mechanism 16 is connected to the main spray pipe 141 and multiple inlet pipes 152 respectively to supply alkaline solution to the main spray pipe 141 and the multiple inlet pipes 152. It includes an alkaline solution tank 161 for storing the alkaline solution, a supply pipe 162 connected to the alkaline solution tank 161, and a pump 163 connecting the alkaline solution tank 161 and the supply pipes 162. Specifically, the pump 163 is selected as a corrosion-resistant centrifugal pump.

[0034] In this embodiment, the liquid supply mechanism 16 further includes a circulation pipe 164 disposed between the liquid supply pipe 162 and the alkali tank 161. The pump 163 and the circulation pipe 164 are respectively disposed at both ends of the liquid supply pipe 162. The circulation pipe 164 transports excess alkali solution from the liquid supply pipe 162 that has not entered the main spray pipe 141 and the inlet pipe 152 to the alkali tank 161. By setting up the circulation pipe 164, excess alkali solution from the liquid supply pipe 162 that has not been used by the main spray pipe 141 and the inlet pipe 152 is transported back to the alkali tank 161, thereby realizing the recycling of alkali solution, avoiding waste, and maintaining stable system pressure.

[0035] Waste liquid tank 17, located below alkali tank 151, is used to collect alkali liquid dripping from mesh conveyor belt 12. During the conveying of alkali dough, a small amount of alkali liquid may drip from the edge of the dough or mesh conveyor belt 12. Waste liquid tank 17 can effectively collect this part of the alkali liquid, avoiding pollution of the ground and equipment. Specifically, the bottom of waste liquid tank 17 can be provided with a drain port connected to alkali tank 161 or independent waste liquid collection bucket.

[0036] Reference Figures 6 to 12 As shown, the oil spraying device 2 includes a conveying mechanism 21, a first oil spraying mechanism 22, an image detection mechanism 23, a second oil spraying mechanism 24, and a control mechanism.

[0037] The conveying mechanism 21 allows the alkaline dough, after proofing and slitting, to pass sequentially through the first oil spraying mechanism 22, the image detection mechanism 23, and the second oil spraying mechanism 24 to complete the oil spraying treatment on the surface of the alkaline dough. Specifically, the conveying mechanism 21 includes a frame 211 and a dough conveyor belt 212 mounted on the frame 211 for conveying the alkaline dough. Multiple alkaline doughs can be arranged in a row and conveyed forward by the dough conveyor belt 212, allowing the first oil spraying mechanism 22 to spray multiple alkaline doughs simultaneously. The surface of the dough conveyor belt 212 can be provided with anti-stick or anti-slip textures as needed to ensure that the dough maintains a stable posture during conveying and does not roll or deviate. Furthermore, the dough conveyor belt 212 is a commonly used conveying structure in the food preparation field, and its specific structure and working principle will not be further elaborated here.

[0038] The first oil spraying mechanism 22 sprays oil onto the passing alkaline dough. It includes two oil spraying seats 221 positioned opposite each other on the conveying mechanism 21, a swing frame 222 pivotally positioned between the two oil spraying seats 221, multiple oil spray nozzles 223 spaced apart on the swing frame 222, an oil inlet assembly 224 communicating with the multiple oil spray nozzles 223, a swing assembly 225 mounted on the oil spraying seats 221 to drive the swing frame 222 to swing, and two connecting rods 226 connecting the two oil spraying seats 221. The multiple oil spray nozzles 223 are located above the conveying surface of the conveying mechanism 21. During the oil spraying process, the swing assembly 225 drives the swing frame 222 relative to the conveying surface. Mechanism 21 oscillates up and down, ensuring even spraying of grease onto the surface of the alkaline dough. Multiple oil nozzles 223, driven by the oscillating component 225, oscillate back and forth, significantly expanding the coverage and spraying angle of the dough surface. Compared to a fixed spraying method, this method effectively adapts to the curved shape of the alkaline dough surface, ensuring a uniform and continuous oil film on the dough surface and cuts, avoiding localized missed sprays or oil accumulation. This provides a reliable guarantee for the integrity of the cuts and the aesthetic appearance of the product after baking. Specifically, two oil spray seats 221 are located on both sides of the frame 211, and two connecting rods 226 are located below the dough conveyor belt 212. Furthermore, the oil nozzles 223 employ atomizing nozzles, and since atomizing nozzles are existing technology, their specific working principle will not be further elaborated here.

[0039] The swing frame 222 includes two swing seats 2221 respectively disposed on two oil injection seats 221, two swing vertical rods 2222 respectively disposed on the two swing seats 2221, a swing horizontal rod 2223 connected between the two swing vertical rods 2222, and two fixing members 2224 respectively disposed between the two swing vertical rods 2222 and the swing horizontal rod 2223. The swing vertical rods 2222 are swingably disposed on the opposite swing seats 2221 via a swing shaft 2225. Multiple oil injection nozzles 223 are spaced apart on the swing horizontal rod 2223. During oil injection, the swing assembly 225 drives the swing shaft 2225 to rotate, thereby causing the swing vertical rods 2222 and the swing horizontal rod 2223 to swing, and thus causing the multiple oil injection nozzles 223 to swing together with the swing horizontal rod 2223. Specifically, the swing crossbar 2223 is vertically movable between the two swing vertical bars 2222. Each end of the swing crossbar 2223 has a connecting block 22231 that connects to the opposite swing vertical bar 2222. Two fixing parts 2224 fix the connecting blocks 22231 to the swing vertical bars 2222. The swing crossbar 2223 is adjustable vertically. Through the cooperation of the connecting blocks 22231 and the fixing parts 2224, the spraying height of the oil nozzle 223 can be flexibly adjusted according to the size and curved surface characteristics of the dough, ensuring that the oil nozzle 223 is always at the optimal spraying distance, further improving the uniformity of oil coverage on the curved surface and cut edges. This structure allows the first oil spraying mechanism 22 to be applicable to alkaline dough of different specifications while ensuring the stability of the spraying quality, exhibiting good versatility and practicality.

[0040] The swinging vertical rod 2222 includes a swinging part 22221 connected to the relative swinging shaft 2225 and two extension rods 22222 that are disposed opposite to each other and extend upward on the swinging part 22221. A connecting block 22231 is movably disposed on the two extension rods 22222, and a fixing member 2224 is disposed between the connecting block 22231 and the extension rods 22222. Specifically, the connecting block 22231 is provided with two through holes 22232 for the extension rods 22222 to pass through.

[0041] The fixing component 2224 includes a fixing screw hole 22241 that extends inward on the connecting block 22231 and is opposite to the extension rod 22222, and a fixing bolt 22242 that is threaded into the fixing screw hole 22241. By cooperating with the fixing screw hole 22241 and the fixing bolt 22242, the swing crossbar 2223 that has completed the height position adjustment can be locked. The height adjustment process is simple and quick and does not require disassembly of other parts.

[0042] The oscillating assembly 225 includes an oscillating motor 2251 mounted on the oil spray base 221, a reducer 2252 connected to the oscillating motor 2251, and a coupling 2253 connecting the output shaft of the reducer 2252 and the oscillating shaft 2225. Specifically defining the structure of the oscillating assembly 225, the reducer 2252 converts the high-speed rotation of the oscillating motor 2251 into a low-speed, high-torque output suitable for oil spraying oscillation. With the connection between the coupling 2253 and the oscillating shaft 2225, it effectively absorbs installation errors and impact vibrations during operation, ensuring that the oscillating frame 222 swings smoothly and at precise angles, thereby improving the consistency and repeatability of the oil spray nozzle 223 spraying the dough surface.

[0043] The oil inlet assembly 224 includes two mounting blocks 2241 mounted opposite each other on the swing frame 222, an oil inlet main pipe 2242 supported between the two mounting blocks 2241, a plurality of oil inlet branch pipes 2243 spaced apart on the oil inlet main pipe 2242, and an oil delivery pipe 2244 connected to one end of the oil inlet main pipe 2242. Specifically, the plurality of oil inlet branch pipes 2243 are respectively connected to a plurality of fuel injectors 223; one end of the oil delivery pipe 2244 extends outward and connects to an oil source, wherein the oil source can be an oil storage tank containing grease, and an oil pump connected to the oil delivery pipe 2244 is installed in the oil storage tank to deliver the grease in the oil storage tank to the plurality of fuel injectors 223. Furthermore, the grease can be vegetable oil or other greases that can achieve the above-mentioned effects.

[0044] The image inspection mechanism 23, located behind the first oil spraying mechanism 22, performs visual inspection on the alkaline dough after one oil spraying cycle to determine whether the surface of the alkaline dough is evenly coated with oil. Specifically, the image inspection mechanism 23 includes an inspection frame 231 mounted on the conveying mechanism 21, multiple inspection blocks 232 spaced apart on the inspection frame 231, and multiple inspection cameras 233 respectively mounted on the multiple inspection blocks 232. The multiple inspection cameras 233 are located above the conveying surface of the conveying mechanism 21 and are used to acquire surface images of the alkaline dough on the conveying mechanism 21 after one oil spraying cycle. Furthermore, the inspection cameras 233 are industrial cameras.

[0045] The second oil spraying mechanism 24 is located behind the image detection mechanism 23. Based on the signal fed back by the image detection mechanism 23, it performs a second oil spraying on the alkaline dough with uneven oil spraying. Specifically, the structure of the second oil spraying mechanism 24 is the same as that of the first oil spraying mechanism 22. Its specific structural composition and working principle will not be described in detail here.

[0046] The control mechanism connects to and controls the operation of the first oil spraying mechanism 22, the image detection mechanism 23, and the second oil spraying mechanism 24. The detection camera 233 feeds back the acquired image information to the control mechanism. The control mechanism processes the signals from the detection camera 233 and controls the operation of the second oil spraying mechanism 24 based on the processing results. Specifically, it controls one or more nozzles 223 in the second oil spraying mechanism 24 to work in conjunction with the oscillating component 225 to achieve targeted re-spraying of the alkaline dough after the first oil spraying, ensuring the uniformity of oil spraying on the surface of the alkaline dough. Specifically, a photoelectric sensor can be installed on the frame 211. The control mechanism controls the operation of the first oil spraying mechanism 22 based on the data fed back from the photoelectric sensor, specifically controlling the operation of multiple nozzles 223 and the oscillating component 225. Furthermore, the control mechanism can employ a programmable logic controller (PLC). Example

[0047] A type of pretzel bread comprises the following ingredients by weight: 45 kg high-gluten flour, 15 kg water, 5 kg low-gluten flour, 1.39 kg fresh yeast, 0.8 kg salt, 2.5 kg butter, 1.5 kg shortening, 5 kg pure milk, 1.5 kg whole milk powder, 0.03 kg baking powder, 2 kg sorbitol, 1 kg maltitol, 0.5 kg glycerin, 10 kg maltitol, 0.5 kg erythritol, 0.085 kg calcium propionate, 0.05 kg sorbic acid, and 1.2 kg fructose syrup.

[0048] Its preparation method specifically includes the following steps: Step 1: Put the weighed ingredients for the lye bread into a horizontal mixer and mix until the dough surface is smooth to obtain the basic dough. Then, put the shaped basic dough into a dough forming machine to obtain multiple lye doughs of uniform size. The diameter of the lye dough is 15±0.5cm, the total weight of the lye dough is 75g, and the weight of its filling is 10g. Step 2: The obtained alkaline dough is conveyed to the alkaline spraying device 1. The alkaline solution is sprayed onto the top surface of the alkaline dough and the bottom of the alkaline dough is immersed at the same time. The alkaline solution treatment time is controlled within 18 seconds. The alkaline solution used is a 4% sodium hydroxide solution. Step 3: The alkaline dough that has been treated with alkali solution is sent to the proofing device for proofing, and then the top surface of the proofed alkaline dough is cut using the cutting device. Step 4: The alkaline dough that has been cut is put into the oil spraying device 2, so that the oil is evenly sprayed on the surface of the alkaline dough. Step 5: After the oil spraying treatment, the alkaline dough is put into the baking device for baking. After cooling, polylysine solution is sprayed on the surface of the shaped bread to obtain the alkaline bread. The polylysine mixture is obtained by mixing 6 grams of polylysine with 1000 grams of 75% alcohol. Step 6: Package the obtained pretzel bread. Nitrogen gas and a double-effect oxygen absorber are required during packaging.

[0049] Specifically, in step 1, when mixing the bread ingredients, follow these steps: First stage: Stir at 60 rpm for 240 seconds; Second stage: Increase speed to 75 rpm, stir for 800 seconds until the stage of lifting up, then maintain the speed and continue stirring for another 500 seconds; Third stage: Increase the speed to 80 rpm, mix for 60 seconds, then open the lid and scrape the oil from the edges into the dough; Fourth stage: Control the speed to 75 rpm and stir for 120 seconds until the gluten is developed. At this time, the surface of the basic dough is smooth, the oil is fully absorbed, and the temperature of the basic dough is controlled at 27±1℃. After mixing, let it rest for 12 minutes before putting it into the dough forming machine.

[0050] In step 3, the conditions for proofing the alkaline dough are as follows: relative humidity of 62%, temperature of 37±1℃, and proofing time of 25 minutes; and when making the cut, the length of the cut is 5.2cm, the depth is 2±0.3cm, and the width is 1±0.3cm.

[0051] In step 5, when the baking device bakes the lye dough, the top heat of zone one is 120℃ and the bottom heat is 100℃; the top heat of zone two is 145℃ and the bottom heat is 110℃; and the bottom heat of zone three is 210℃, with a total baking time of 25 minutes. The temperature of the cooling zone is 24℃ and the humidity is 55±5%, so that the finished bread cools to a center temperature of 35±1℃. This application optimizes the formula and preparation method of pretzel bread. By omitting the "freezing and setting" step in existing methods, the resulting pretzel bread has a more fluffy and soft texture, a moist mouthfeel, effectively delays aging and hardening, and improves excessive chewiness. Furthermore, it uses a combination of sugar alcohol and glycerin to reduce water activity, combined with surface spraying of polylysine solution for antibacterial purposes. This dual preservation strategy, combining internal and external methods, significantly extends the product's shelf life from the traditional 3-5 days to over 90 days. Simultaneously, by omitting the "freezing and setting" step and optimizing the process into a continuous "shaping-alkali spraying-cutting-oil spraying-baking" flow, the production cycle is greatly shortened, equipment utilization and capacity are improved, perfectly meeting the requirements of modern food industry production lines. Moreover, an oil spraying device 2 is installed to spray the pretzel dough after cutting, ensuring a uniform oil coating on the cut surface. This effectively solves the problem of dough shrinkage causing the cut to stick together, ensuring the integrity of the product's shape and the clarity of its texture after baking, significantly improving the finished product's aesthetics and quality consistency.

[0052] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made in accordance with the scope of the present invention and the contents of the specification should still fall within the scope of the present invention.

Claims

1. A method for preparing pretzel bread, characterized in that: The alkaline bread comprises the following ingredients by weight: 100 parts high-gluten flour, 34-36 parts water, 10-15 parts low-gluten flour, 3-4 parts fresh yeast, 1.5-2.5 parts salt, 5-10 parts oil, 10-15 parts pure milk, 3-5 parts whole milk powder, 0.05-0.2 parts baking powder, 5-15 parts sugar alcohol, 5-10 parts sugar substitute, 0.3-0.6 parts food preservative, and 0.5-1.5 parts glycerin. Its preparation method specifically includes the following steps: Step 1: Put the weighed pretzel bread ingredients into a horizontal mixer and mix until the dough surface is smooth to obtain the basic dough. Then, send the shaped basic dough into a dough forming machine to obtain multiple pretzel doughs of uniform size. Step 2: The obtained alkaline dough is transported to the alkaline spraying device. The alkaline solution is sprayed onto the top surface of the alkaline dough and the bottom of the alkaline dough is immersed at the same time. The alkaline solution treatment time is controlled at 15-20 seconds. Step 3: The alkaline dough that has been treated with alkali solution is sent to the proofing device for proofing, and then the top surface of the proofed alkaline dough is cut using the cutting device. Step 4: After the alkaline dough has been cut, it enters the oil spraying device so that the oil is evenly sprayed on the surface of the alkaline dough. Step 5: After the oil spraying treatment, the alkaline dough is put into the baking device for baking. After cooling, polylysine solution is sprayed on the surface of the shaped bread to obtain the alkaline bread. The polylysine mixture is obtained by mixing 6 grams of polylysine with 1000 grams of 75% alcohol.

2. The method for preparing pretzel bread according to claim 1, characterized in that: In step 3, the conditions for proofing the alkaline dough are as follows: relative humidity of 60-65%, temperature of 37±1℃, and proofing time of 20-30 minutes.

3. The method for preparing pretzel bread according to claim 1, characterized in that: In step 5, when the baking device bakes the lye dough, the top heat of zone one is 120℃ and the bottom heat is 100℃; the top heat of zone two is 145℃ and the bottom heat is 110℃; and the temperature of zone three is 210℃, with a total baking time of 22-30 minutes. The temperature of the cooling zone is 22-26℃ and the humidity is 55±5%, so that the finished bread cools to a center temperature of 35±1℃.

4. The method for preparing pretzel bread according to claim 1, characterized in that: The diameter of the alkaline dough is 15±0.5cm.

5. The method for preparing pretzel bread according to claim 1, characterized in that: In step 3, the incision is 5-5.5cm long, 2±0.3cm deep, and 1±0.3cm wide.

6. The method for preparing pretzel bread according to claim 1, characterized in that: In step 1, when mixing the bread ingredients, follow these steps: First stage: Stir at 60 rpm for 240 seconds; Second stage: Increase speed to 75 rpm, stir for 800 seconds until the stage of lifting up, then maintain the speed and continue stirring for another 500 seconds; Third stage: Increase the speed to 80 rpm, stir for 60 seconds, then open the lid and scrape the oil from the edges into the dough; Fourth stage: Control the speed to 75 rpm and stir for 120 seconds until the gluten is developed. At this time, the surface of the basic dough is smooth, the oil is fully absorbed, and the temperature of the basic dough is controlled at 27±1℃. After mixing, let it rest for 10-15 minutes before putting it into the dough forming machine.

7. The method for preparing pretzel bread according to claim 1, characterized in that: It also includes step 6, which involves packaging the obtained pretzel bread. Nitrogen gas and a double-effect oxygen absorber are required during packaging.

8. The method for preparing pretzel bread according to claim 1, characterized in that: The food preservative is composed of calcium propionate and potassium sorbate in a mass ratio of 1.7:

1.

9. The method for preparing pretzel bread according to claim 1, characterized in that: The sugar alcohol is selected from one or more of sorbitol and maltitol; the fat is selected from one or more of butter and shortening; the sugar substitute is selected from one or more of maltitol and erythritol.

10. The method for preparing pretzel bread according to claim 1, characterized in that: The alkaline spraying device includes a conveyor frame, a mesh conveyor belt mounted on the conveyor frame, a drive mechanism for driving the mesh conveyor belt, an alkaline spraying mechanism for spraying alkaline solution onto the top surface of the alkaline dough, an alkaline soaking mechanism for soaking alkaline solution into the bottom of the alkaline dough, and a supply mechanism for supplying alkaline solution to the alkaline spraying mechanism and the alkaline soaking mechanism. The alkali soaking mechanism soaks the bottom of the alkali dough conveyed on the conveying mechanism with alkali solution. It includes an alkali tank supported on the conveyor frame and located below the alkali dough, multiple inlet pipes extending into the alkali tank, and multiple outlet holes spaced apart on the inlet pipes. The outlet holes are arranged opposite to the bottom of the alkali dough and their openings face upward, so that the alkali solution flowing out of the outlet holes gushes upward to form a fountain phenomenon. The gushes out alkali solution can overflow the mesh conveyor belt and contact the bottom of the alkali dough. During alkali treatment, the alkali spraying mechanism sprays alkali onto the top surface of the alkali dough from above, while the alkali impregnation mechanism gushes out alkali through its inlet pipe and upward-facing outlet, creating a fountain-like phenomenon. The gushes-out alkali overflows the mesh conveyor belt and comes into contact with the bottom of the alkali dough, thus achieving simultaneous top spraying and bottom impregnation.

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