Cereal Chemistry& QualityFinal Exam, FallSemester 2017 1.
Summarize the differentbranches of science that have relevance to dry milling of wheat. Wheat grains have to go through a number of millingprocesses so as to augment product quality and integrity. Dry milling in simpledefinition refers to the separation of the structural parts of the grain as efficientlyas possible so as to realize the desired quality products.
Wheat grains initiallyhave to pass through a rigorous meticulous cleaning process which can be up tosix steps of cleaning to get rid of all the unwanted impurities emanating fromthe farmers field such ash debris, sticks and metal objects prior to milling.The process of cleaning wheat is a continuous process throughout the milling ofthe wheat, this is evidenced by the magnetic separators that are mainly used topick up all possible available metal objects. The vibrating or rotating drum separators remove thingslike woods, wheat straw. Aspirators then take advantage of the air power toremove the dust form and other lighter impurities. Usage gravity (de-stoner)comes in handy to remove stones that could be the same weight as the wheatkernels. The grain then passes through a disc separation machine which mainlyanalyses precisely the kernel size and deliberately rejects all anomalies in termskernels with irregular size and shape. The intense scourer action then removesthe outer husk of the kernel and the dirt in the kernel crease as this isthought to be the breading point of unwanted microorganism.
The entoleter willthen use the centrifugal force to break apart the faulty kernels or insect eggsof which aspiration will then reject them from the milling flow. Recent advancemills can actually utilize electronic color separators that makes the cleaningprocess to be easy. After cleaning the wheat grains the wheat will be ready for the millingprocess but however a tempering process is needed prior to the grain being milled.Tempering is a process of adding water into the wheat grain of which water entersmostly through the wheat germ.
Tempering is done so to toughen the bran skin tohold water rather than creating bran powder which can lead to dark high mineralflours. It is carried out to ensure the separation of the dark colored branfrom the light-colored endosperm which leads to a desirably good quality flourto meet consumer needs. to ensure thedesired moisture content of finished products and to aim for consistency. Soakingcan be done for 6-24hrs depending on the wheat moisture level and also itshould be noted that temper water can be treated with either chlorine or ozoneto maintain sanitation throughout the tempering process.
After tempering the wheat grain is ready for milling. There are about 5roller meals in a typical milling system. The main of the process of milling isto successfully get as possible of the pure endosperm from the bran and thegerm. This process needs a lot of efficiency because it is standard milling practicethat the bran and the germ should not make its way into the flour as this leadsto undesirable flour quality.
The broken wheat grains coming from the corrugatedfine rolls is sent back to the top and then allowed to drop through sifters toreduce the presence of bran from the wheat granular particles. The siftingprocess is a screening process that separates the large from the top while thesmaller particles sift to the bottom.