DE2704880B2 - Process for extruding cereals - Google Patents

Description

The invention relates to a method for extruding cereals in an extrusion chamber

Hill CIIIUI 1 BUiai., Ill "J * .l \ .IJIW I W. uvijwiillvvnv uiiiihw," with the density of the extrudate controlled independently of the wear of the sleeve.

A known digester extruder for corn semolina has an inlet for the cereal grains which leads into an extrusion chamber which has a sleeve within which a screw conveyor rotates. The outlet end of the extrusion chamber has a housing forming a narrowed outlet. Corn meal which is introduced into the extrusion chamber is exposed to a high pressure, and the friction that entsieht between the conveyor screw and the sleeve, holds a temperature of about 150 ⁰ C upright in the gelatisiert of corn. As the corn is extruded through the mouths in the mold plate, it expands due to the pressure drop. A rotating knife cuts the extrudate into specific lengths.

Because of the friction of the worm in the sleeve, the sleeve will wear. The density of the extrudate depends on various factors, in particular on the condition of the core, but also on the feed speed in the chamber, the speed of the screw, the temperature in the chamber, the The mouth area and the moisture content of the grains. Has when using a new sleeve the extrudate is usually high density and hard texture, and often contains small particles of not expanded grain. As the sleeve wears, the density of the extrudate decreases and eventually becomes unusable for the finished product, d. H. that the density of the product is no longer controllable by the wear of the extruder sleeve is influenced. When the density is high. is the weight of the raw Cereal grains required are correspondingly high and this affects the raw material cost.

For economical production, the lowest permissible density is desired, so that a minimum of excess weight is achieved in the bags or corresponding containers in which the extruded product comes onto the market. However, if the feed rate or the .Schncckendreh / ühl is reduced in order to achieve a product of low density / u , the volumetric output of the extruder is reduced accordingly. If there is another cable, the die plate is changed so that the mold openings are changed, or if a different sleeve is used to change the neck size, the extruder must be temporarily shut down, whereby production

is interrupted.

The object of the invention is, in a method of the generic type, the extrusion process for cereal grains perform so that a controlled

■> Change in the density of the extrudate is achieved without the volumetric discharge from the extruder is adversely affected, and in particular density changes in the extruded cereal grains due to wear of the jacket in the extrusion

Turn off the ki chamber.

According to the invention it is proposed that the material to be extruded depending on the Wear of the sleeve already extruded and ground cereals to a grain size of less than 1400 μm

i> be added, with the addition at a new Sleeve is 15% and goes towards O with wear of the sleeve

The temperature in the extrusion chamber is increased by cooling to a value between 115 and 165 ° C

controlled

The expanded cereal grains are z. B. ground in a rotary sieve, being in a mesh cylinder be introduced, in which a rotating shovel the grains against the mesh screen

2 ~ j presses. The resulting particle size, which can be varied by changing the cylinder, is not uniform, but does not exceed the value of 1400 μm.

_{i ()} example!

In this example, the machines used have a Kocher extruder and a rotating screen of the type described above, as well as a ribbon blade mixer. The mixer is used to mix water with the

r> cereal grains and then the addition with the moist Mixing cereal grains.

The raw grains are corn kernels and the additional grains are corn kernels that are in one previous extrusion process expanded and then

4M to a particle size of not more than 1400 μm have been ground. The additional cereal grains can be waste material from a previous one Be or contain an extrusion process. A test container of known size and capacity is used to periodically take a sample of the extrudate.

The extruder is ^{heated to about 150 °} C. (but not above 165 " ¹ ° C.), then started and the extrusion chamber is fed with raw cereal grains alone. The extrudate is collected and a sample with the

Vi sample container taken. Whom the extrudate is one unacceptably high density, an estimated amount of grain additive will be with the raw cereal grains mixed in a ribbon blade mixer. Since the grain addition is drier than raw geire grains, a compensatory

Vi sating amount of water in the raw cereal grains Mixer added before the grain additive is introduced. The resulting mixture with a Moisture content of about 13 to 15 weight percent is then introduced into the extrusion chamber. That

wi extrudate now shows a decrease in density when a sample is taken from the test container. If the decrease in density is too great, the additive will Reduce the addition of grains until a usable extrudate is obtained. The original exirudal higher

h-, density, made from the grains alone is. and also extrudate with too low a density are collected and then ground in a sieve to rinse more usable (cereal grain / usat / is obtained.

As the expanded cereal kernels are produced, the extrusion chamber sleeve continues to wear, and as the expanded cereal wears, the density of the extrudate decreases. This decrease in density is indicated using the test container and the amount of granule additive to keep the extrudate within usable predetermined density limits is immediately reduced. The density of the extrudate continues to decrease until the extrudate density becomes unusable. Then the operation of the extruder is stopped and the worn sleeve is replaced. Then the grain additive is added to the cereal grains in the mixer. When a new sleeve is inserted, the extrudate density is highest. To reduce this density, a maximum of 15 weight percent additive is required in order for the density to be reduced to a useful level.
The cut lengths of the extrudate will be

Tabel

baked until crispy, flavored and filled into bags, containers or the like.

Example 2

Ί The machines used are the same as for Example I. The procedure is also the same as in Example 1, except that in the mixer ordinary potato powder is mixed with the moist raw corn. The weight percentage

ίο Potato powder is 10%. The one controlling the density Addition remains the same, i.e. H. Corn kernel that has been expanded by a previous extrusion process is and then has been ground to a particle size below 1400 μm. Accordingly, the maximum The proportion of added grains does not exceed 15% by weight of the maize / potato mixture.

In the table below, which refers to the same extruder, typical extrudates are the only maize (Example 1) contain products A, while typical extrudates contain maize and potato (Example! 2) Products B are.

product Extrusion mix density machinery Extruda exit consumption in g / l in kg / h in m ³ / h default 47 82 1.68 (i.e. without grains additive) A. mil S percent by weight 44 82 1.83 Grain assortment " Λ with 7 percent by weight 37 70 1.86 Grain addition default 65 95 1.49 (i.e. without grains additive) B. with 3 percent by weight 62 95 1.51 Grain addition B. with 6 percent by weight 55 88 1.57 Grain addition B. with 9 percent by weight 51 82 1.58 Grain salt B. with 12 percent by weight 47 82 1.71 KOmCrZUSaI /

It has been found that every product has a useful range of densities. The table shows that for products A and B, the amount of mixture that is required with increasing grain addition and as the continuous volumetric output of the extruder increases. As a result, there is a more efficient use of raw material and a reduced weight content per container or sachet is obtained, which in turn reduces the use of flavors per container content results.

Claims (1)

Claim: Method for extruding cereals in an extrusion chamber with a sleeve in which a The screw conveyor revolves around the controlled density of the sleeve regardless of the wear and tear of the sleeve Extrudates, characterized in that the material to be extruded depending on the Wear of the sleeve already extruded and ground to a grain size of less than 1400 μπι Cereals are added, the addition being 15% for a new pod and with wear and tear the sleeve goes to 0.