A method for the gluten preservation gradient slow cooling shaping of high gluten wheat flour

Abstract

The application discloses a high-gluten wheat flour gluten-retaining gradient slow-cooling shaping method and belongs to the technical field of grain deep processing. In the application, the high-gluten wheat flour is tempered to a moisture content of 25%-30%, annealed in a temperature window of 50-55 DEG C for 13-15 minutes, and the gluten protein network is completely retained; then, the section gradient slow-cooling shaping is adopted: the first section is cooled to 40-42 DEG C at a rate of 3-5 DEG C / min, the second section is cooled to below 35 DEG C at a rate of 1-2 DEG C / min, the gluten network is fully relaxed in the cooling process, and the elasticity and ductility are maintained; and finally, low-temperature drying is carried out. The application is a pure physical zero-addition process, the obtained product has a wet gluten retention rate of greater than or equal to 85%, a GI value of less than or equal to 65, and a RS3 melting temperature of greater than or equal to 120 DEG C, and the industry problem that the reduction of the GI value and the retention of the gluten cannot be achieved simultaneously is perfectly solved.

Description

Technical Field

[0001] This invention belongs to the field of deep grain processing technology, specifically involving a purely physical gradient slow cooling and shaping method for high-gluten wheat flour, which is used to reduce the glycemic index while retaining the high gluten processing performance of the flour. Background Technology High-gluten flour is a fundamental ingredient in high-end flour products such as toast, ramen, and dumpling wrappers. Traditional high-gluten flour typically has a glycemic index (GI) between 70 and 85, classifying it as a high-GI food. Existing methods for reducing GI all come at the cost of sacrificing gluten processing performance. The applicant's prior art discloses annealing at temperatures below the critical thermal denaturation temperature of gluten proteins (approximately 55°C) to preserve the gluten network and generate RS3 resistant starch. However, the cooling and setting process after annealing is equally crucial to the quality of the final product. Conventional rapid cooling causes the gluten protein network to shrink drastically, generating internal stress, which reduces gluten elasticity and deteriorates its drawing properties. While natural cooling can protect the gluten network, excessively low cooling rates can cause RS3 lattice regression and a rebound in the GI value. How to precisely control the cooling rate to protect both the gluten network and the RS3 lattice remains an unsolved technical challenge in this field. Summary of the Invention Purpose of the invention The purpose of this invention is to provide a gradient slow cooling and shaping method for high-gluten wheat flour. By precisely controlling the cooling rate in segments, the RS3 lattice structure is locked while protecting the elasticity of the gluten network, thus simultaneously achieving high gluten content and low GI. Technical solution The present invention includes the following steps: (1) conditioning to a moisture content of 25%-30%; (2) annealing in a constant humidity environment of 50-55℃ and 80%-95% for 13-15 minutes; (3) using segmented gradient slow cooling for shaping - the first stage is cooled to 40-42℃ at 3-5℃ / min, and the second stage is cooled to below 35℃ at 1-2℃ / min; (4) drying at a low temperature not exceeding 45℃. Those skilled in the art can achieve the cooling rate control based on conventional parameters such as material thickness and airflow, which is a common technique in the field of food engineering. Core Mechanism After annealing, the material is at a high temperature, requiring the gluten protein network to relax slowly, while the RS3 lattice needs to be quickly locked to prevent retrogradation. 40-42℃ is the critical transition temperature range for RS3 locking and gluten relaxation: above this range, RS3 lattice retrogradation may occur; below this range, the gluten network fluidity is significantly reduced, preventing sufficient relaxation. This invention simultaneously satisfies these two requirements through segmented gradient cooling: the first stage cools at a relatively rapid rate to 40-42°C, quickly moving away from the dangerous temperature range of starch retrogradation and locking in the RS3 lattice; the second stage cools at a slower rate to below 35°C, providing the network with sufficient relaxation time within the critical temperature range of gluten protein's transition from a rubbery to a glassy state, maintaining its elasticity and extensibility. The precise coordination of these two rate windows is the key difference between this invention and conventional cooling methods, and also the fundamental guarantee for achieving both high gluten strength and low GI. Those skilled in the art will understand that a cooling rate of 2-6℃ / min for the first stage and 0.5-3℃ / min for the second stage can achieve some effect, but 3-5℃ / min and 1-2℃ / min are preferred. Beneficial effects (1) It perfectly solves the industry problem of reducing GI and preserving gluten in high-gluten flour, and achieves the simultaneous achievement of the two contradictory goals of "high gluten" and "low GI" for the first time. (2) The gradient slow cooling parameters are precisely controllable and suitable for industrial continuous production. (3) It is purely physical with zero additives, and the ingredient list contains only wheat flour. Detailed Implementation Example 1 (Gradual slow cooling of high-gluten wheat flour) Take 1000g of hard red winter wheat flour (14.2% protein, 33% wet gluten), add water to adjust to 28%, and heat at 48℃. Anneal at 51℃ and 85% humidity for 14 minutes. After annealing, perform gradient slow cooling: the first stage cools from 51℃ to 40℃ with cold air at 3.5℃ / min over 3 minutes; the second stage cools from 40℃ to 33℃ with cold air at 1.5℃ / min over 8 minutes. Dry at 42℃ until the moisture content is 12.0%, then sift to obtain the product. The resulting product exhibits high wet gluten retention, a significantly reduced GI value, and an RS3 melting temperature exceeding 120℃. The resulting toast demonstrates excellent stretching properties, showing no significant difference from untreated high-gluten flour, and remains soft even after being left at room temperature for 48 hours. Comparative Example 1 (Rapid Cooling and Shaping) The cooling method of Example 1 was changed to forced cooling: 2°C cold air was used, and the surface temperature of the material dropped sharply from 51°C to below 40°C within 30 seconds and to 25°C within 3 minutes. The average cooling rate exceeded 10°C / min (far higher than 5°C / min in the initial stage), while the other conditions remained unchanged. The resulting product showed a significant decrease in wet gluten retention, a significant reduction in the length of the gluten strands, and bread collapse. This demonstrates that rapid cooling causes severe contraction of the gluten network, leading to a deterioration in the product's processing performance. Comparative Example 2 (Natural Cooling and Shaping) The cooling method in Example 1 was changed to natural cooling (the average cooling rate was about 0.3℃ / min, and it took about 50 minutes to drop from 51℃ to below 35℃), while the other conditions remained unchanged. The resulting product showed no significant reduction in GI value, and the melting temperature of RS3 was below 120°C. This demonstrates that the excessively low natural cooling rate led to lattice reversion in RS3, resulting in the loss of the GI-reducing effect. Comparative Example 3 (annealing temperature exceeds 55℃ red line) The annealing temperature of Example 1 was changed to 58°C, which exceeds the critical temperature of 55°C for thermal denaturation of gluten protein, while the other conditions remained unchanged. The resulting product exhibited a significant decrease in wet gluten retention and loss of fiber-drawing properties. This demonstrates that even with gradient slow cooling above the 55°C threshold, the irreversible degradation of the gluten network cannot be reversed. Detection methods The wet gluten content and retention rate were determined according to GB / T 14608, the GI value was determined according to the standard method of ISO 26642:2010, and the RS3 melting temperature was determined by differential scanning calorimetry. Industrial applications This invention can be implemented on existing continuous grain conditioning-annealing-cooling-drying production lines. The core equipment includes a dual-shaft differential atomizing continuous conditioning tank, a closed mesh belt continuous annealing tower with a temperature control accuracy of ±0.5℃ across the entire range, a multi-stage air-cooled conveyor belt (first-stage air cooling and second-stage air cooling connected in series), and a low-temperature airflow drying device.

Claims

1. A method for gradient slow cooling and shaping of high-gluten wheat flour to preserve gluten, characterized in that, Includes the following steps: a. Conditioning: Add water to high-gluten wheat flour and condition it to a moisture content of 25%-30%, and control the temperature at 45-50℃. This allows the starch to absorb water and swell, while preserving the natural three-dimensional network structure of gluten protein. b. Isothermal annealing: The conditioned material is kept in a constant humidity environment with a relative humidity of 80%-95% for 13-15 minutes within a temperature window of 50-55℃, so that the partially gelatinized amylose molecules attach in an orderly manner and rearrange the lattice along the intact three-dimensional network of gluten protein to form high melting point RS3 type resistant starch. c. Gradient slow cooling and shaping: The annealed material is cooled to below 35°C in a segmented gradient slow cooling method. The first segment is cooled to 40-42°C at a rate of 3-5°C / min, and the second segment is cooled from 40-42°C to below 35°C at a rate of 1-2°C / min. This allows the gluten protein network to fully relax during the cooling process, maintaining its elasticity and extensibility. d. Low-temperature drying: Dry the cooled material at a temperature not exceeding 45°C until the moisture content is below 13%.

2. The method according to claim 1, characterized in that, The high-gluten wheat flour mentioned in step a has a protein content of ≥13.5% and a wet gluten content of ≥30%.

3. The method according to claim 1, characterized in that, The annealing temperature in step b is 51-52℃, the annealing time is 14 minutes, and the temperature at any temperature measuring point in the annealing equipment does not exceed 54℃ during the annealing process.

4. The method according to claim 1, characterized in that, In step c, the first stage of cooling reduces the material temperature from the annealing temperature to 40-42°C within 2-4 minutes, and the second stage of cooling reduces the material temperature from 40-42°C to 32-35°C within 5-10 minutes.

5. The method according to claim 1, characterized in that, The annealing process in step b is carried out in an environment with a relative humidity of 82%-88%.

6. A high-gluten, low-glycemic index wheat flour, characterized in that, The wheat flour prepared by the method according to any one of claims 1-5 simultaneously satisfies the following conditions: wet gluten retention rate ≥85%, GI value ≤65, RS3 type resistant starch melting temperature ≥120℃, and the ingredient list contains only wheat flour.

7. The wheat flour according to claim 6, characterized in that, RS3 resistant starch grows orderly along the intact three-dimensional network of gluten proteins.

8. The application of the wheat flour according to claim 6 or 7 in the preparation of high-gluten, low-glycemic index flour products, wherein the flour products include, but are not limited to, toast, ramen, dumpling wrappers, frozen pizza bases, and frozen dough.