TECHNOLOGY OF CEREALS The beall degerminator finished product. Finer stocks are combined with coarser fractions of the through-stocks from the Possibly the most important innovation in dry Beall, for treatment in the milling system maize milling was the introduction of degerming stages. The Beall degerminator is unfortunately named, as it neither reverses the process of Milling germination, nor totally or exclusively removes The feed to the milling system, viz. large fU S dry milling plants today, medium and fine hominy, germ roll stock, and (TD)system. Its virtue lie ering -degerming embryo They are separated by a series of roller as an essential stage in the tem large particle size grits dried and emerging as a diverse range of final with low fat content and low fibre content(about 0.5%), suitable for manufacture of corn flakes products. They are fed to the mill, each entering The favoured feed stock to the TD system in at an appropriate point: the large and medium the U. S A is No. 2 yellow dent corn. In Africa hominy at the first break, the fine hominy and white maize is used. After cleaning and tempering to 20% moisture content, it passes to the Beall The milling is carried out on roller mills, using This machine consists of a cast iron cone, rotating futed rolls, a traditional flow containing up to at about 750 rev/min on a horizontal axis, within sIxteen distinct stages. The grindings with fluted a conical, stationary housing, partly fitted with of 1. 25:1 or 1.5: 1) fatten the embryo fragme llowing them to be removed by sieving. The outer surface. The maize is fed in at the small products are sifted on plansifters and are aspirated end and it works along to the large end, between the two elements. The protrusions on the rotor rolls. The break system releases the rest of the abrasive action, also breaking the endosperm into embryo as intact particles, and cracks the larger particles of various sizes and degrees of purity. nilling system for maize bears some resemblance The Beall discharges two types of stock: the to the earlier part of the wheat milling system tail stocks which are too large to pass through the screens, consisting mainly of fragmented (which is described more fully below--p. 141) endosperm,and the through-stock consisting as far as B2 reduction roll (2nd quality roll,in largely of bran and embryo, ne proportions of the U.S. A)viz. the break, coarse reduction and different sized particles can be controlled by the the scratch systems, but is extended and modified in comparison with this part of the wheat milling setting of the Beall(Brekke and Kwolek, 1969). to make a more thorough separation of the large Drying, cooling and grading quantity of germ present. Modern practice is to use a much shortened system Tail-stock from the Beall degerminator is dried The action of the rolls should be less severe at to 15-15.5% moisture content in rotary steam the head end of the mill than at the tail end in tubes at a temperature of 60%-70oC and cooled to order to minimize damage to the germ while 320-38C by aspiration with cold air. The dried simultaneously obtaining maximum yields of oil stock is sifted to produce a number of particle and oil-free grits size fractions. The coarsest fraction, between 3. 4 The finished coarse, medium and fine grits and 5.8 mm, consists of the flaking or hominy meal and four products are dried to 12-14% grits, originating from the vitreous parts of the moisture content on rotary steam tube driers aspirator and drier-cooler, before emerging as a s.The germ concentrate consists largely of endosperm. They may pass through a fu avily damaged embryos with an oil content138 TECHNOLOGY OF CEREALS The Beall degerm inator Possibly the most important innovation in dry maize milling was the introduction of degerming stages. The Beall degerminator is unfortunately named, as it neither reverses the process of germination, nor totally or exclusively removes the germ. It was introduced in 1906 and it is used in the majority of U.S. dry milling plants today, as an essential stage in the 'tempering-degerming' (TD) system. Its virtue lies in its potential to produce a high yield of large particle size grits with low fat content and low fibre content (about OS%), suitable for manufacture of corn flakes. the U.S.A. is No. 2 yellow dent corn. In Africa white maize is used. After cleaning and tempering to 20% moisture content, it passes to the 'Beall'. This machine consists of a cast iron cone, rotating at about 750 rev/min on a horizontal axis, within a conical, stationary housing, partly fitted with screens and partly with protrusions on the inner surface. The rotor also has protrusions on its outer surface. The maize is fed in at the small end and it works along to the large end, between the two elements. The protrusions on the rotor and the housing rub off the hull and embryo by abrasive action, also breaking the endosperm into particles of various sizes and degrees of purity. The Beall discharges two types of stock: the tail stocks which are too large to pass through the screens, consisting mainly of fragmented endosperm, and the through-stock consisting largely of bran and embryo. The proportions of different sized particles can be controlled by the finished product. Finer stocks are combined with coarser fractions of the through-stocks from the Beall, for treatment in the milling system. Milling The feed to the milling system, viz. large, medium and fine hominy, germ roll stock, and meal are mixtures of endosperm, bran and embryo. They are separated by a series of roller milling, sifting and aspiration stages before being dried and emerging as a diverse range of final products. They are fed to the mill, each entering at an appropriate point: the large and medium germ roll stock at the second roll. The milling is carried out on roller mills, using fluted rolls, a traditional flow containing up to sixteen distinct stages. The grindings with fluted rolls (15-23 cuts per cm rotating at a differential of 1.25: 1 or 1.5: 1) flatten the embryo fragments, allowing them to be removed by sieving. The products are sifted on plansifters and are aspirated. The mill is divided into a break section, a series of germ rolls and a series of reduction and quality rolls. The break system releases the rest of the embryo as intact particles, and cracks the larger grits to produce grits of medium size. The whole milling system for maize bears some resemblance to the earlier part of the wheat milling system (which is described more fully below - p. 141) as far as B2 reduction roll (2nd quality roll, in the U.S.A.) vzz. the break, coarse reduction and the scratch systems, but is extended and modified in comparison with this part of the wheat milling quantity of germ present. Modern practice is to Drying, cooling and grading use a much shortened system. Tail-stock from the Beall degerminator is dried The action of the rolls should be less severe at to 15-15.5% moisture content in rotary steam the head end of the mill than at the tail end in tubes at a temperature of 60"-70°C and cooled to order to minimize damage to the germ while 32"-38"C by aspiration with cold air. The dried simultaneously obtaining maximum yields of oil stock is sifted to produce a number of particle and oil-free grits. size fractions. The coarsest fraction, between 3.4 The finished coarse, medium and fine grits, and 5.8 mm, consists of the flaking or hominy meal and flour products are dried to 12-14% grits, originating from the vitreous parts of the moisture content on rotary steam tube driers. endosperm. They may pass through a further The germ concentrate consists largely of aspirator and drier-cooler, before emerging as a heavily damaged embryos with an oil content The favoured feed stock to the TD system in hominy at the first break, the fine hominy and setting Of the Beall (Brekke and Kwolek, 1969)' to make a mOre thorough separation of the large