Hence the different spellings such as bulgur (Germany/Europe), bulgar / burgal / burghoul (Turkey), burghol / borgol (Arabia), Pourgouri (Greece). In the Bible, bulgur is mentioned under the name arisah.
It is a particularly important staple food in the Middle East, the Balkans and Asia. Due to its long shelf life and good flow properties, its high nutritional value and easy preparation, Bulgur is very popular in many parts of the world. In comparison with other wheat products, bulgur is one of the nutritionally valuable dishes. Depending on the type of preparation or use, different bulgur varieties and fraction sizes are used.
In the plant installed by Amandus Kahl / Schule, cooking times of 3 to 7 minutes are achieved, depending on the product size.
Process for the Production of Bulgur
An important factor in the production of bulgur are the wheat varieties that are used. The protein, ash, vitamin and mineral contents must be determined first before deciding on the corresponding process. Nutrient losses should be as low as possible. The plant for the production of bulgur can be divided in the following groups: Cleaning, soaking, cooking, drying, cooling, tempering, whitening, groating, classifying, bagging.
In order to determine soaking time, soaking temperature, starch modification degree, thiamine losses, swelling factor, water absorption, cooking time, cooking temperature, and drying parameters of the corresponding wheat type, on the basis of which the plant was designed, tests were carried out at the pilot plant (Fig. 2) in Reinbek.
Canadian durum and durum wheat (type CWRS) with a bulk density of 0.82 kg/l were processed in the pilot plant of Amandus Kahl / Schule. The soaking time was about 40 - 60 minutes at a soaking temperature below the gelatinization temperature of the wheat starch. Depending on the product, the cooking time was between 15 - 20 minutes at a cooking time that could be set from 110 - 130°C. The moisture content after soaking is 38 - 45% H20, depending on the type of product; and the starch modification degree is between 40 and 50 %, measured using to the AMG method. It is important not to add too much water during the soaking process so that the caryopsis will not swell too much and damage the grain. Otherwise, substances contained in the grain will escape (vitamin losses).
Since the soaking water was reused in the industrial plant, it had already been tested for suspended solids, odour, COD value, BOD5 value, conductivity and pH value, nitrogen, ammonium, nitrite, nitrate etc. during the tests in the pilot plant before the appropriate water treatment plant was planned.
Putting the test results into practice
After evaluation of all parameters tested in the pilot plant, the industrial plant to be installed in an existing eight-storey building could be designed.
A plant for an input capacity of 2.5 t/h was projected on the assumption that cleaned raw material without shrivelled grain, chalky grain, foreign seeds and impurities would be available, i.e. a homogeneous input product. During the planning process of the plant, it had to be taken into account that an existing maize mill would continue to be in operation during the installation of the bulgur plant. That was quite a challenge for the local staff as the maize mill was located in the same building.
The plant works automatically and is monitored and controlled by the operators in the control room using the installed monitoring devices.
The cooker with a diameter of 2.5 m and a length of approx. 10 m had to be lifted by 30 m and transported into the building. The product contacting parts in the wet and dry section are made of stainless steel. Filter systems ensure the discharge of the exhaust air. In order not to fall below the dew point in the drying plant, the exhaust air of the fluidised bed drier and that of belt drier were mixed.