Wheat Blending and Annealing Processes

14 October 201614 min reading

Noyan Erik who is a renowned expert in the milling industry in Turkey has stated in an article that “the art of milling starts with finding the right wheat and purchasing it at the right price. The process continues with the cleaning and annealing the wheat in a right manner”. Just like Noyan Erik, many experts renowned for their respective works on the milling industry state that the processes such as the cleaning and annealing the wheat have a tr82kapakentryemendous impact on the production efficiency and the quality of the wheat.

Changes in people’s consumption habits and the globalization of the world lead to the continuous development of new products. Despite this, the wheat and thus, flour has preserved its grace throughout history. Well, have you ever wondered from which processes the wheat harvested on the fields goes through from the milling to their being served at our dining tables?

As the Milling Magazine, we touched upon the supply of the raw material in the production of flour and the process of wheat cleaning. In this issue, we have dwelled on the blending and annealing procedures carried out after the processing process. Based on the articles and interviews of the leading names in the industry, we tried to prepare a compilation by specifying the significance of the blending and annealing processes and the issues to be paid utmost importance. You can find in this compilation any information regarding the process to clean the wheat and prepare it for annealing, wheat blending, blending process and the factors affecting the annealing.

Noyan Erik who is a renowned expert in the milling industry in Turkey has stated in an article that “the art of milling starts with finding the right wheat and purchasing it at the right price. The process continues with the cleaning and annealing the wheat in a right manner”. Just like Noyan Erik, many experts renowned for their respective works on the milling industry state that the processes such as the cleaning and annealing the wheat have a tremendous impact on the production efficiency and the quality of the wheat.

CLEANING OF THE WHEAT The most important thing to consider in the milling industry is the classification of the wheat in terms of its color and hardness and its cleaning and blending. For this reason, the foreign materials such as the straw, waste, stones, sand and black seeds must be removed with the cleaning machinery manufactured for various purposes.

The cleaning process is as follows: the incoming raw material must be purified through the waste material purifier from the materials larger than wheat (straw, waste) and those materials smaller than the wheat (sand and small black seeds). Then, the gran lighter than wheat must be separated through the air duct. And large and small stones are separated at the stone separator machine. The wheat is sent to the peeling machines after the purification from the foreign materials. Here, wheat shells are rubbed and brushed and thus, the dust particles on the wheat are cleaned. After this procedure, the peeled shells and light grains are separated from the wheat through the air ducts. After the separation procedure, the wheat is separated from the small and round black seed mix ingredients in small and large grains trieur machines and from long grains in the long grains trieur machines.

PURPOSE, SIGNIFICANCE AND DURATION OF THE ANNEALING The purpose of the flour factories is to produce various types of flour for different practices. Various practices include flour for baklava, pastry, bread, special breads, bagel and shredded dough sweet and with additives, angelfood, cakes, pizza and similar products. The production of the desired quality of flour is possible with the separation of endosperm from the wheat shells and wheat milling, not milling of the wheat together with its shells just like traditional stone mills. For this purpose, rolls have been developed and instead of milling the wheat at once, there have been developed some ways to separate the endosperm from the wheat shells and mill the wheat. So, annealing of the wheat is compulsory.

The aim of annealing the wheat is to ensure the optimum level of water in the wheat. With the provision of the optimum level of water in the wheat, rendering the physical properties of the wheat suitable for the milling and in particular, enhancing the nutritional values is the main target. The quenching process of the grain in order to ensure the optimum level of water prior to the milling or drying up the excessive water in the grain is called annealing. The temperature and resting periods are of great importance in the successful conclusion of the annealing of the wheat, wetting the wheat and distributing the water to the overall grain.

The annealing procedure is rather a complicated and significant procedure in contrast to how it looks. Any trivial modification or change in the annealing of the wheat is directly reflected on the quality of the wheat.

Today, the wheat the cleaning procedures of which are completed at the flour factories is transferred to the angled annealing machines for the annealing procedure through elevator. The newly developed angled annealing machines ensure the more intense blending of the wheat and distribute the water throughout all the wheat. This procedure is known as the 1st annealing procedure. The resting period in the 1st annealing may be shortened and extended according to the softness or hardness of the wheat. For instance, the resting period of the 1st annealing of the red and hard wheat varies between 10 and 15 hours. After the 1st annealing procedure, the humidity of the wheat is measured and the humidity is adjusted at 15,5%-16% for the white and soft wheat and 16,5%-17% for the red and hard wheat and according to the type of the wheat, it is transferred to the 2nd annealing procedure. In the 2nd annealing procedure, just like the 1st one, the angled annealing machine is used.

The resting period in the second procedure of annealing lasts 4-5 hours for white and soft wheat and 8-10 hours for the red and hard wheat. In annealing procedures, the resting period and annealing rates of the wheat for biscuits and soft white wheat, a different type of wheat, may be reduced. The annealing period for the red and hard wheat can be up to 48 hours. The annealing period for the durum wheat (pasta wheat) is 10-15 hours for the 1st annealing and 5-6 hours for the 2nd annealing. As the removal of the barley and oats and black spots on the durum wheat is of great importance, the long grains trieur machine must be definitely used.

Transfer of the wheat with its wet shell during the annealing procedure to the B1 section will be influential in the prevention of the breakages.

Furthermore, the direct milling of the unannealed wheat may cause the wheat to break just like bulgur wheat and the failure to separate the shell from the wheat and thus, leading to the milling the wheat with its shell. The resulting milled wheat may cause the production of the black-colored flour. The importance of the annealing procedure is manifested here. The annealed and rested wheat may lead to loosening of the shell due to the humidity and the water permeates deep into the wheat essence thanks to the humectation. The annealing procedure ensures the color change of the wheat and accelerates the separation of the shell and provides advantages for the processing of the wheat.

WHEAT BLENDING The gluten, sedimentation and index values of any type of wheat must be measured in the blending procedures and these values must be as follows: Wet gluten (min): 27 1st sedimentation (min): 28 2nd sedimentation (min): 35 Index (min): 70 and the blending procedure must be concluded in accordance with these values. Carrying out the blending procedure after the 2nd annealing is of utmost importance because in case where the blending and humidity procedures are carried out at the same time, then great imbalances in humidity may be observed during the blending of two different types of wheat. While a certain type softens greatly, the other type may remain dry. Another result that may emerge in case where the blending procedure is carried out in the 1st annealing, the aforementioned values may not be secured and the result may be unqualified and imperfect production of flour at the end of the milling. But, the aforementioned values may be secured if the blending is carried out during the transition from the 2nd annealing procedure to blending. In case of a small change in these values, the blending rates can be changes and the deterioration of the product quality can be prevented.

FACTORS AFFECTING THE ANNEALING PROCEDURE • Effects of the Wheat Types on the Annealing Procedure The wheat is generally classified into three groups as durum wheat, wheat for bread and for biscuits. While the semolina factories process the durum wheat, the flour factories generally mill the wheat for bread. Some special facilities process the wheat for biscuits. For this reason, in the case of the flour factories, the first thing that comes to mind is those facilities milling the wheat for bread.

The wheat for bread includes many types in terms of its hardness, planting time and breeds. That is why their features vary considerably. In the annealing procedure, the hardness of the wheat must be taken into consideration. The period of annealing may vary between 6 and 72 hours in terms of the hardness of the wheat.

• Effects of the ambient air on the annealing procedure The humidity of flour produced in accordance with the standards must be 14.5% at most. The excessive humidity causes such effects as bitterness and speedy deterioration during the storage and waiting period. For this reason, rather than the humidity of the wheat to be milled, the humidity of the resulting flour is of significance. The wheat is provided with humidity according to the humidity of the finished product. While providing this humidity, the ambient temperature is important. The humidity which is 17% in the summer months may be decreased to 15% in the winter months. This depends on the temperature and the moisture in the air.

• Effects of the Wheat Blending on the Annealing Procedure Blending is one of the most important factors on the quality of milling. The blending of different wheat therefore requires more annealing silos given that their annealing period varies and more types of wheat are blended.

EFFECTS OF THE ANNEALING ON THE QUALITY OF MILLING AND YIELD The aim of annealing wheat is, as specified above, to ensure the wheat shall become more elastic with water. Given that unannealed wheat shell is more fragile, the wheat shell will crumble at the first rolls. At the last rolls, it is impossible to get the flour under the shell; on the contrary, the wheat shell will break up more. The crumbling of the shell causes the deterioration of the milling.

The yield is the rate of the resulting flour amount to the milled wheat amount. The annealing is the procedure that ensures the prevention of the crumbling of the shell by increasing the elasticity of the wheat shell. In the milling of the ideally-annealed wheat, the yield will be at the desired level and approximately 80-82% flour and 18-20% bran must be obtained.

The wheat with humidity levels different than these values causes significant changes on the yield. Excessive level of humidity cause the flour near the shell to stick to the shell and thus, the flour is wasted. For this reason, while the resulting flour level decreases, the amount of bran increases. On the other side, low level of humidity will cause the fragility of the shell and the resulting flour amount will increase while the amount of bran decreases. It must be noted that the increased amount of flour shows that the flour includes bran and the low quality of flour.

ANNEALING METHODS Classic Annealing (Cold Annealing) It is the annealing procedure carried out at the ambient temperature. It is thought that the resting period of the wheat varies between 24 and 72 hours according to its features and environmental conditions. With this method, while the wheat gets the required level of water in a few minutes, its distribution in the grain takes a long time.

Given that a long period of time is required for the uniform distribution of the water in the grain, there is a need for high annealing silo capacity. This is evaluated as a disadvantage as it increases the costs.

Warm and hot annealing While a 1-3 day-long-period is needed for the balanced distribution of the water in the case of the cold annealing, this time is reduced to 1-1.5 hours in the warm resting conditions carried out at a temperature between 30 °C and 46 °C. Despite that, a 24 hour-resting-period is recommended in order for the grain to regain its optimum physical features.

The hot annealing procedure is carried out through a modification of the warm annealing method. What’s different is that the annealing stage may have a temperature between 46 °C and 60 °C. Even though it is possible to increase the temperature up to 70 °C, the procedure time is quite critical at this temperature and the annealing is concluded in a shorter period of time. As the gluten and baking values of the wheat may be reduced at the excessive heat, the application of hot annealing procedure is low. This type of annealing method is mainly applied in the reduction of the proteolytic activity.

Steam Annealing In recent years, the steam annealing method that requires a short period of time and that is easy to control and a more uniform annealing has started to be adopted first in Germany followed by the United States of America and Canada. The steam annealing method includes the increase in the heat of the wheat via the steam and the loss of evaporation resulting from the cooling of the wheat till the temperature required for the milling and provision of water. Through the application of steam, the penetration of the heat into the grain takes 20-30 seconds. This period is 3 minutes for the annealing with dry air and radiator. With the steam method, the grain is dampened. The heat increases by nearly 10 °C for the 1% water condensation of the grain.

Annealing with microwave The microwave is used in the food industry for such procedures as cooking, defrosting, tempering, drying, freeze drying, pasteurization, sterilization, cooking and heating in an oven. There are a lot of researches on the use of the microwaves in the grain industry.

In a research where Elgün and Türker (1995) analyzed the shell-endosperm separation by the use of the microwaves in the annealing of the wheat and their effects on the features of the wheat, the samples of the annealed wheat were milled with and without the microwave application. It was observed that the microwave application increased the yield of flour and decreased the amount of ashes. But the increase in the yield causes an increase in the ash amount. As this means more production of flour in a unit of wheat, it may provide an economical contribution. The increase in the amount flour and the decrease in the amount of ash through the application of microwave is an indication of better shell-endosperm separation.

Annealing with Ultrasound The ultrasound method is extensively used in many fields of the food industry for the homogenization, crystallization, cleaning, extraction, foam breaking, degassing, and drying, mixing and similar applications. Its application is quite limited in the grain processing. It is also used to increase the efficiency of the drying and sieving procedures and the acceleration of the damping process and germination in the production of malt.

For further information of the annealing and blending procedures, you can obtain 50th issue of the Milling Magazine dated February 2014.

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