How to Measure the Gluten Index

How to Measure the Gluten Index

In flour production, a very important test item is to use a gluten index meter to measure the gluten index of flour. The gluten index represents a value of flour gluten degree, generally between 0-100%, and the instrument for measuring the gluten index is the gluten index meter. Generally speaking, the larger the percentage, the higher the flour’s gluten. According to this data, it can be judged which type of flour (high-gluten, medium-gluten, and low-gluten) the flour belongs to so that the flour can be selected in a targeted manner when making flour products.

What Is The Gluten Index?

The gluten index refers to the percentage of the gluten mass and the total gluten mass that the wet gluten of wheat flour passes through a certain aperture sieve plate under the action of centrifugal force and remains on the sieve plate. The gluten index is proportional to the strength of the gluten.

Use a gluten quantity and quality tester to add 10g of flour or whole wheat flour to 5ml of saltwater, mix in a washing cup with a sieve for 20 seconds to form a dough, and wash with salt water for 5 minutes to obtain gluten. Under centrifugal action, the wet gluten content and gluten index can be calculated according to the prescribed method for gluten measurement.

How to Measure the Gluten Index

Wet gluten is a substance mainly composed of gliadin and glutenin, which is viscous, extensible, and similar to rubber. In evaluating flour quality, the content of wet gluten in the flour is one of the important evaluation indicators. In the flour quality inspection, the gluten tester is a widely used measurement to measure this data accurately. The instrument has a fast measurement speed, high accuracy, saving time, labor, and labor. In addition, it is close to the real value and can be used to judge the flour quality in a real and effective way.

The gluten index instrument is a special instrument used to measure the gluten content and quality (gluten index) in flour. The gluten index is used to evaluate the strength of gluten. It consists of the gluten washing instrument, an index measuring instrument, and a drying instrument. This gluten index meter is suitable for determining wheat flour and whole wheat flour. It is widely used in food and gluten processing, grain and oil scientific research institutions, grain storage, and other departments.

Principle of Gluten Tester

Wheat gluten is composed of gluten protein and gluten protein, insoluble in water, and can swell with water to form an elastic-plastic colloidal hydrate. A certain amount of flour or whole wheat flour and salt water are mixed in a washing cup with a screen for the 20S to form a dough and then washed with salt water to remove water-soluble substances such as starch in the dough, and gluten can be obtained.

Under centrifugal force, the gluten is centrifuged out of the water, adhering to the surface, and part of the wet gluten passes through the perforated plate of the sieve box. After weighing and calculation, the wet gluten content and gluten index in the flour or whole wheat flour can be obtained. After drying the moisture of wet gluten, the content of dry gluten and gluten water holding rate can be obtained by weighing and calculation.

To quickly and effectively complete mixing, washing, centrifugation, weighing, etc., during the measurement process, the gluten measurement instrument mainly includes:

  • A gluten washing machine.
  • A centrifuge.
  • A dryer.
  • A capacity for holding sodium chloride buffer solution.

In addition, it is composed of a cylinder, a beaker used for washing water and starch for mobile phones, a gluten washing room for holding wheat flour samples, etc. Together, these components form a gluten analyzer, which cooperates to complete the gluten measurement.

Why Choose a Gluten Meter

The gluten meter is mainly used to measure the quality and quantity of gluten. Therefore, it is an important quality indicator in determining flour quality. In the past, it was measured by hand washing, which is also the manual method. With the development of science and technology, Most of them are measured by gluten meter, that is, the instrument method. The main reasons for the final decision to use the gluten meter are as follows:

Accurately Assess The Quality Of Gluten.

The manual determination of gluten quality is based on the stretching method, which is judged according to the length of gluten stretching and the human feeling of “force.” The gluten meter is used to measure the quality of gluten because it adopts the centrifugal method to measure gluten quality. It can correctly evaluate gluten quality and has the advantages of reliable results and quantitative representation.

Difference between a Single-Headed Gluten Meter and a Double-Headed Gluten Meter

What’s the difference between a gluten meter and a double-headed gluten meter? As the name suggests, the double-head gluten meter has two measuring heads, which have a wider measurement range and can be operated individually or simultaneously, which saves a lot of time and effectively improves the test efficiency.

What Are The Reasons Why The Gluten Analyzer Cannot Wash Out Gluten Normally?

The gluten measuring instrument comprises a gluten washing machine, a centrifuge, and a drying machine. It has the advantages of fast, stable, accurate, and convenient operation. Therefore, what are the reasons the measurement work cannot be carried out normally, and the gluten analyzer cannot wash out the gluten normally?

In measuring the gluten index, the gluten measuring instrument has a process of kneading the noodles. Adding too much liquid during the kneading process will cause the instrument not to wash out the gluten normally.

The failure of the liquid supply system to supply liquid normally can also cause this situation to occur.

Usually, maintenance and cleaning are not in place, resulting in clogging of the screen.

The kneading time is too short, or the deterioration of the flour causes it.

When the room temperature is too low, below 15°C, the NaCl buffer solution should be heated to about 22°C.

From the above reasons, we can see that a large part of the gluten tester cannot wash out gluten normally due to improper operation and inadequate maintenance. The correct operation method and steps of the gluten tester, and in the test process, operate in strict accordance with the regulations, and secondly, do maintenance and cleaning work. After the test, wash the washing cup, screen, etc., with water. If the above situation occurs in using the gluten tester, it can be solved one by one according to the above reasons.

Gluten Assay System Preparation before Use

Although it is said that using a gluten measurement system to determine the gluten index of flour has many advantages, to obtain accurate test results, there are still many details that need to be paid attention to in the actual operation process.

Generally speaking, a gluten measurement system determines the wet gluten content. The usual practice is to pour the powder sample into a metal sieve equipped with a fine mesh, add sodium chloride solution, start the instrument, and mix the dough. 

However, in the process of the manufacturer’s operation, due to some reasons, in many operations, the phenomenon of netting often occurs soon after the washing starts, failing the measurement. Furthermore, through analysis, it is found that the over-wetting of the fine mesh generally causes meshing. Therefore, in the process of preparing the dough with the gluten measurement system, to avoid this phenomenon and improve the success rate of the measurement.

Gluten Tester Application: Gluten Meter to Know the Protein Content in Wheat Flour

Why can you use a gluten meter to measure wheat flour’s gluten index and know the protein content of wheat flour? Studies have shown that insoluble protein accounts for about 90% of the total protein content. Therefore, using a gluten meter to measure the gluten content in wheat flour reflects the protein content in wheat flour to a certain extent. Therefore, the application of the gluten meter is a rough understanding of the protein content in wheat flour.

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