this description refers primarily to milo , a grain sorghum , but also applies to other grains such as wheat , corn , oats , etc . as used herein , kernel means an individual grain . in the first step , bulk grain is conditioned by wetting with a solution of propionic acid in water ; this is a penetrating solution which acts to soften the grain coats . the propionic acid is mixed with sufficient water to achieve the desired rates of application per ton of grain . enough solution is applied to thoroughly wet the grain , with any excess solution allowed to drain off . a typical rate of application of the conditioning agent , for milo , is 6 - 8 oz . per ton . a commercially available solution is sold under the name &# 34 ; e - z flake &# 34 ; by loveland industries , a colorado company . after the conditioning solution is applied , sufficient time is allowed to pass for the conditioner to soften the grain coat ; during this period the grain is held in conditioning hopper 10 . the length of time to achieve a proper weakening of the grain coat varies considerably . a typical period for softening for milo is 6 - 24 hours , with an optimum range being 10 - 18 hours . softening the grain coat makes the remaining steps in the process easier and more energy efficient . the next step is heating the grain in roaster 20 ; a gas - fired roaster is preferred . a jet pro model 10 roaster is used in the prototype , but other types of roasters are equally useful . during heating , internal moisture inside grain kernels is converted to steam . if the heating is carried to a sufficiently high temperature , the kernels will pop like popcorn . a feature of the present invention is to heat the grain to a temperature just below a temperature which will make the kernels pop -- this temperature is important during the rolling step , as described below . the appropriate temperature for each grain type is based on empirical dam . temperature of the grain is monitored by measuring the temperature of the atmosphere inside the roaster 20 . for milo , the temperature is about 310 ° f ., and the residence time of the grain inside the roaster is about 70 seconds . small grain particles called fines may be separated from the grain and exhausted from the roaster with the hot exhaust air flow . the air flow passes through a centrifugal , cone - shaped separator , which separates the particulate matter from the air stream . the particulate fines are then introduced into the roller mill 40 to be reincorporated into the product . a similar procedure for recapturing fine particulate material is used for the exhaust air from the cooler , described below . when the grain has been heated to the proper temperature , i . e ., to a temperature just below that which will cause the individual kernels to burst , the grain must be quickly moved to the roller mill 40 . it is necessary to perform this transfer quickly so that the grain will not cool appreciably , because the effectiveness of the crushing step is dependent on grain temperature . an airlock 30 provides the passage between roaster 20 and roller mill 40 ; the airlock construction is necessary because the roaster is under a positive pressure relative to ambient atmospheric pressure , and the airlock prevents exhaust air from the roaster from scattering the heated grain . the airlock 30 comprises a cylindrical chamber having a wall 31 with an inlet 32 through which grain enters from the roaster , and an outlet 34 to the roller mill . inlet 32 and outlet 34 are openings in the cylindrical wall 31 which are slots or some other shape . an axial rotatable shaft 36 extends the length of the airlock cylinder , and is rotated by external means such as an electric motor . in the preferred embodiment , the airlock shaft is driven by a reduction gear which is turned by a variable - speed electric motor , so that the rotational speed of the shaft can be adjusted to accommodate different rates of grain flow . attached to the axial shaft are three or more longitudinal baffles 38 which extend the length of the airlock cylinder . the baffles 38 are sized to fit closely against the inner surface of the airlock cylindrical wall 31 so as to block the heated air from blowing into the roller mill from the roaster . a series of compartments inside the airlock are defined by the baffles 38 . as the baffles rotate , grain moves into one compartment from the roaster via inlet 32 , is moved around an inner circumference of the airlock until adjacent the airlock exit ; the grain then flows into the roller mill 40 for crushing via outlet 34 . because both time and distance between roaster and roller mill are short , the grain enters the roller mill at substantially the same temperature at which it left the roaster . vaporization of moisture inside individual kernels of heated grain produces internal pressure in the grains . the pressure is a function of the temperature of the grain and the length of time the grain has been heated . both these factors , temperature and heating time , are controlled so that the pressure inside the grains is just below the bursting pressure of the grains . when this pressure is exceeded , the grains burst like popcorn . as the kernels pass between the rollers 42 of roller mill 40 , the mechanical pressure of the rollers , added to the existing pressure inside the kernels , causes the kernels to burst . on completing its pass between the rollers , the expanded , less - dense grains are pressed into flakes . generally the rollers 42 are set at a spacing of about 1 / 32 inch , and the resulting flakes are about the same thickness . corn requires a slightly wider roller spacing . the prototype of the invention uses a ferrell - ross flaking mill ; other flaking and roller mills are also useful . the flakes are scraped from the rollers and moved via a drag conveyor 48 to a cooler 50 , in which a stream of air is used to cool the flaked grain . currently , a sprout - waldron double pass cooler is used , in which the grain makes two passes through the cooler 50 . at the end of the first pass , in the upper part of the cooler , a spray of water is applied via water spray - bar 52 to the still - warm flaked grain . the addition of water is to return the final product to a moisture content similar to that of unprocessed grain , or to a moisture content suitable for the intended use of the flaked grain . the optimum moisture content is predetermined , and is typically about 14 %. testing with moisture meters before and after processing allow the necessary amount of added water to be determined . during the second pass of the flaked grain through the cooler 50 , enzyme spray bar 54 applies a spray of enzyme solution to the grain . the enzyme increases the digestibility of the grain in the stomachs of ruminants , and is commercially available as &# 34 ; digest - m &# 34 ; ( for milo ) and &# 34 ; digest - c &# 34 ; ( for corn ) from loveland industries . as with the exhaust from the roaster , the exhaust from the grain cooler is filtered to capture fines blown off the grain . the fines are reintroduced into the final product to eliminate waste . after its final pass through the cooler 50 , the flaked , treated grain is moved to a distribution hopper 60 . from distribution hopper 60 the grain product is loaded into trucks or other means of transportation . where the grain is not shipped in bulk , it may be moved to another area of the mill for bagging . the embodiments shown and described above are only exemplary . i do not claim to have invented all the pans , elements , or steps described . various modifications can be made in the construction , material , arrangement , and operation , and still be within the scope of my invention . the restrictive description and drawing of the specific examples above do not point out what an infringement of this patent would be , but are to enable one skilled in the art to make and use the invention . the limits of the invention and the bounds of the patent protection are measured by and defined in the following claims .
an improved process for treating grain used for animal feeds includes steps of conditioning the grain to soften the grain coats , quickly heating the grain to a temperature just below a temperature sufficient to cause the grains to burst , compressing the heated grain between rollers to cause the grain to burst , further pressing the burst grains into flakes , and cooling the flaked grain . during the cooling step water is added to bring the moisture content of the final product to a desired level ; digestibility enzymes and other additives are added with the water .