A general modification method of medium-gluten wheat flour with both gluten and blood sugar reduction

Abstract

The application discloses a general modification method of medium-gluten wheat flour with both gluten and blood sugar reduction, and belongs to the technical field of grain deep processing. The medium-gluten wheat flour is tempered to moisture of 24%-26%, annealed for 9-11 minutes in a temperature window of 56-60 DEG C, and the starch gelatinization degree is controlled to be 25%-50%, so that part of the gelatinized amylose is orderly rearranged along the endogenous skeleton under the premise of guaranteeing that the gluten network is basically complete, and high-melting-point RS3 type resistant starch with a melting temperature of greater than or equal to 120 DEG C is formed; then, conventional air cooling and shaping and low-temperature drying are carried out. The application is a pure physical zero-addition process, the obtained product has a wet gluten content of greater than or equal to 26%, a GI value of less than or equal to 62, and is suitable for common steamed buns, steamed buns, ordinary noodles and other popular staple foods.

Description

Technical Field

[0001] This invention belongs to the field of deep grain processing technology, specifically relating to a purely physical modification method for medium-gluten wheat flour, which reduces the glycemic index while retaining basic processing properties. Background Technology Medium-gluten wheat flour is a basic ingredient in staple foods such as steamed buns, dumplings, noodles, and pancakes. Traditionally, medium-gluten flour has a glycemic index (GI) of 70-80, classifying it as a high-GI food. Unlike high-gluten flour, which requires complete preservation of the gluten network, medium-gluten flour can tolerate some gluten loss in exchange for higher starch modification efficiency, but it still needs to retain a basic gluten network to ensure the elasticity and texture of the finished product. Currently, research on the annealing modification of medium-gluten wheat flour lacks a systematic approach. Existing technologies typically apply the low-temperature, long-time parameters (50-55℃, 13-15 minutes) used for high-gluten flour or the high-temperature, short-time parameters (60-67℃, 8-10 minutes) used for low-gluten flour, failing to simultaneously preserve the gluten content and reduce sugar content of medium-gluten flour. The former results in insufficient starch modification efficiency and a high glycemic index (GI) due to excessively low temperatures; the latter leads to large-scale denaturation of gluten proteins, causing the finished product to lose elasticity and resulting in a crumbly texture in steamed buns. Existing technologies have never proposed a specific annealing scheme for medium-gluten flour, this "intermediate" region. Summary of the Invention Purpose of the invention The purpose of this invention is to provide an annealing method specifically for medium-gluten wheat flour, which maximizes the reduction of GI value while retaining basic processing properties, thereby meeting the needs of the mass staple food market. Technical solution The present invention includes the following steps: (1) conditioning to a moisture content of 24%-26%; (2) annealing for 9-11 minutes in a constant humidity environment of 56-60℃ and 80%-95%; (3) conventionally air-cooling to below 28℃; and (4) drying at a low temperature not exceeding 50℃. Core Mechanism Medium-gluten wheat flour has a gluten network density between that of high-gluten and low-gluten flour, allowing it to withstand slightly higher annealing temperatures than high-gluten flour, but still requiring temperatures below 60℃ to avoid large-scale denaturation of gluten proteins. 56-60℃ is the only effective window balancing gluten retention and starch modification—below 56℃, starch molecular chain mobility is insufficient, modification efficiency is low, and the GI value is high; above 60℃, large-scale denaturation of gluten proteins occurs, the wet gluten content drops below 22%, and the finished product loses its elasticity. 9-11 minutes is the optimal time range within this temperature window for achieving industrial feasibility—below 9 minutes, RS3 formation is insufficient; above 11 minutes, excessive gluten loss occurs. Unlike the gradient slow cooling of high-gluten flour, the cooling requirements of medium-gluten flour are relatively relaxed. Conventional air cooling can meet the shaping requirements, reducing the requirements for equipment precision and making it more suitable for large-scale industrial production. Beneficial effects (1) A special annealing scheme for medium-gluten wheat flour was proposed for the first time, filling the gap between high-gluten and low-gluten flour and solving the industry pain point of existing technologies "applying parameters but not matching either end". (2) It takes into account both processing performance and sugar reduction effect, with wet gluten ≥26% and GI≤62. (3) The cooling method is simple, the equipment investment is low, and it is suitable for large-scale industrial production. (4) It is purely physical with zero additives, and the ingredient list only contains wheat flour. Detailed Implementation Example 1 (annealing of medium-gluten wheat flour) Take 1000g of medium-gluten wheat flour (11.5% protein, 28% wet gluten), add water to adjust to 25%, and heat at 48℃. Anneal at 58℃ and 85% humidity for 10 minutes. After annealing, cool from 58℃ to 27℃ using conventional air cooling within 6 minutes. Dry at 45℃ until the moisture content is 12.0%, then sieve to obtain the product. The resulting product has a wet gluten content of ≥26%, a significantly reduced GI value, and an RS3 melting temperature higher than 120℃. The steamed buns made from this product are soft and elastic, with a taste that is not significantly different from those made from untreated medium-gluten flour. Comparative Example 1 (annealing temperature exceeding 60℃) The annealing temperature in Example 1 was changed to 63°C, while the other conditions remained unchanged. The resulting product had a wet gluten content below 22%, and the steamed buns had a crumbly texture and significantly reduced elasticity. This demonstrates that temperatures exceeding 60℃ cause large-scale denaturation of gluten proteins, resulting in the loss of the processing properties of medium-gluten flour. Comparative Example 2 (annealing temperature below 56℃) The annealing temperature in Example 1 was changed to 52°C, while the other conditions remained unchanged. The resulting product had a high glycemic index (GI), low resistant starch content, and insignificant blood sugar lowering effect. This indicates that excessively low temperature resulted in insufficient starch modification efficiency. Comparative Example 3 (annealing time exceeds the window) The annealing time in Example 1 was shortened to 5 minutes or extended to 16 minutes. At 5 minutes, RS3 formation was insufficient, resulting in a high GI value; at 16 minutes, excessive gluten loss led to a hard texture in the steamed buns. This demonstrates that 9-11 minutes is the optimal balance window for all-purpose flour. Detection methods The wet gluten content was 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 biaxial 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 conventional air-cooled conveyor belt, and a low-temperature airflow drying device.

Claims

1. A universal modification method for medium-gluten wheat flour that balances gluten strength and blood sugar reduction, characterized in that, Includes the following steps: a. Conditioning: Add water to medium-gluten wheat flour and condition it to a moisture content of 24%-26%, while controlling the temperature at 45-50℃; b. Isothermal annealing: The conditioned material is kept in a constant humidity environment with a relative humidity of 80%-95% for 9-11 minutes within a temperature window of 56-60℃, so that the degree of starch gelatinization is controlled at 25%-50%. The partially gelatinized amylose rearranges in an orderly manner along the intrinsic skeleton to form high melting point RS3 type resistant starch with a melting temperature ≥120℃. c. Conventional air-cooling and shaping: The annealed material is cooled to below 28°C using air cooling. d. Low-temperature drying: Dry the cooled material at a temperature not exceeding 50°C until the moisture content is below 13%.

2. The method according to claim 1, characterized in that, The medium-gluten wheat flour mentioned in step a has a protein content of 11%-12% and a wet gluten content of 26%-30%.

3. The method according to claim 1, characterized in that, The annealing temperature in step b is 58-60℃, and the annealing time is 10 minutes.

4. The method according to claim 1, characterized in that, The air cooling described in step c cools the material from the annealing temperature to below 28°C within 5-8 minutes. This can be achieved by those skilled in the art by adjusting conventional parameters such as air volume, air temperature, and material thickness.

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 medium-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 content ≥26%, GI value ≤62, RS3 type resistant starch melting temperature ≥120℃, and the ingredient list contains only wheat flour.

7. The application of the wheat flour according to claim 6 in the preparation of homemade steamed buns, dumplings, ordinary noodles, and pancakes.