Miller Magazine Issue: 132 December 2020

59 COVER STORY MILLER / december 2020 cles and enable the endosperm to separated more effi- ciently from the bran. Shattered small pieces of bran con- taminate the clean, white endosperm, produce flour with high ash content. Therefore, wheat conditioning process gives high flour extraction with lower ash content. 2- To toughen up the germ to separate it from the en- dosperm more easily. The germ is rich in fat. Germ con- tamination of flour shortens the shelf life of flour. 3- To gives the endosperm optimal mellowness that minimizes energy consumption during grinding. In other world to achieve optimal milling conditions. If the wheat is wetter or drier in relation to its optimum milling condi- tions, the system will be out of optimum balance, which results in reduction of flour extraction and nonuniform flour characteristics. 4- To maintain enough endosperm hardness to pro- duce desired amount of starch damage, and optimal par- ticle size distribution. 5- To achieve optimal sieving. Appropriate amounts of the kernel fractions flow to all grinding stages gives opti- mally balanced milling system. 6- To secure the correct percentage of moisture in the finished product. Dry flour also will decrease baking qualities. The gluten matrix will take much longer to de- velop and not be fully hydrated. The result is dry, crum- bly, tough bread dough. MOISTURE CONTENT Generally, the optimum wheat moisture content be- fore first milling machine optimum milling moisture is between 15 and 17%. Moisture distribution among the kernel parts have to be optimum too. For example, if the bran has about 14% moisture and the endosperm have 17% may result dark flour color. On the other hand, if the endosperm moisture at 14.5% and the bran at 18.5% would affect flour yield and the balance of the mill. The optimum milling moisture depend on the following factors: • Type of wheat (soft, hard, semi hard), recommended milling moisture for hard wheat 16.0-17.0%, semi-hard wheat 15.5-16.0%, semi soft wheat 15.0-15.5% soft wheat 14.5-15.0%. • The loss of moisture during milling process because of water evaporation. Moisture loss must be monitored by the miller and compensated for by controlling the amount of added water during conditioning. The mill environment temperature and relative humidity, heat generated during milling are among of the factors which influence the amount of moisture loss. • The desired flour yields. As desired flour extraction increase the optimum moisture content decrease. • The desired moisture content of the final products. The rate of conditioning water can be calculated by following equation: where: “W” is equal to the rate of water required (l/h); “C” is equal to the capacity of grain (kg/h); “Mf” is equal to the target moisture content; and “Mi” is the initial moisture content. CONDITIONING EQUIPMENT One of the main goals of wheat conditioning systems before tempering is to distribute the added water uni- formly in all the kernels of the wheat mix. Generally, tempering mixers can be categorized according to mix- ing speed and its chamber incline. Chamber of tempering mixer can be horizontal and inclined. In each of temper- ing mixer position, the mixing speed could be low-speed and high -speed. Low speed tempering mixer are actually a screw conveyor but with angled paddles. Capacity of mixer and retention time can be adjusted by the angle of paddles on the shaft. High-speed mixers, commonly referred to as inten- sive dampeners. Intensive dampener and inclined inten- sive dampener are the common tempering systems used nowadays. Intensive dampeners disperse the water in the grain mass by an intensive mixer in which the wheat is tumbled with the added water very rapidly. Intensive dampener secure uniform distribution of the added water over all parts of each kernel. As a result of using intensive dampener the addition of up to 7% can be achieved in one step with very uniform water dispersion which de- crease the necessary tempering bins capacity than multi- step methods. Intensive dampener process increases the water penetration rate into kernel by scouring the wheat bran and reducing water surface tension. Since intensive damping system reduces tempering time and makes no need for second conditioning pro- cess it reduces bacterial growth and considered as highly sanitary. MODERN DAMPENING EQUIPMENT Reducing tempering time was the aim of modern dampening equipment, which based on the increasing the rate of water penetration by reducing water surface tension by generating high frequency vibration. Reduc- ing water surface tension enhance the efficiency of wa- ter dispersion over the grain mass and water penetration into the kernel. This equipment does not break the kernel because it does not include scouring process. Debranning “stripping” or “peeling” of wheat kernel can be used to enhance the water penetration rate which reduces the tempering time. These techniques remove or damage the wheat kernel bran layers using high abrasion and friction machines just before milling. Higher flour ex-