OA12196A - Flouring process. - Google Patents

Abstract

Flouring process and equipment comprising surface moistening (1) cereal grains or legume seeds by treating them with vaporized superheated water, impact milling (2) the surface moistened grains or seeds and sieving (3) the milled grains or seeds.

Description

-1- 012196

The présent invention relates to a flouring process and equipment. 5

Traditional wheat flouring equipments are known to beheavy, complicated and costly as they comprise numerous,interconnected milling machines and screening machines. 10 EP0218012 discloses a wheat flouring pretreatment System consisting of a plurality of friction type wheal polishingmachines disposed in sériés, moisture being supplied to thepolishiiig chamber of at least one of the polishing machinesto moisten and soften the entire pericarp of each grain inorder to increase a frictional concact force between cnegrc-ins. EP0218012 however discloses a flouring equipmentwhich, in addition to this ••'heac flouring pretreatmentSystem, still comprises numerous, interconnected millingmachine3 and screening machines. 20 US 3979375 refers to a process for f ract ionatmg the whole-wheat kernel into its bran, germ and endosperm. Thisprocess comprises the steps of tempering the grains inwater and pin milling the wheat kernel. It is stated that. 25 the tempering step allows to increase the whole moisturecontent of the grains and that increasing the watertempérature can accelerate the tempering step. However, itis also stated that care must be exercised to maintain thetempérature below a limit value of about 60°C in order to 30 avoid any damages to the gluten. DE830604 discloses an impact mill which may be used foimilling wheat and other cereal grains which hâve beenprewetted in such a way that the bran gets slightly 35 leathery. DE830604 however discloses a flouring equipmentwhich comprises several such impact mills in sériés. 2 012196 A first object of the présent invention is to provide aflouring process and equipment which not only are light,simple and economical but also are actually efficient. A second object of the présent invention is to provide aversatile flouring process and equipment which may be usedfor milling any kind of cereal grains or legume seeds.

To this end the présent process comprises the steps ofsurface moistening cereal grains or legume seeds bytreating them with vaporized superheated water, impactmilling the surface moistened grains or seeds and sievingthe milled grains or seeds.

Similarly, the présent equipment comprises means forsurface moistening cereal grains or legume seeds bytreating them with vaporized superheated water, these meansbeing connectée! to an impact mill itself connected to asieving machine.

It has surprisingly been found that it is possible withsuch a simple, light and economical process and equipmentto préparé, with a relatively high extraction degree, fromany kind of cereal grains or legume seeds, a flour whichhas a relatively high purity or quality and a relativelywell defined granulometry.

It has also surprisingly been found that, in the case ofwheat flouring, it is possible in this way not only to workvery efficiently but also to take care of wheat gluten,because the grains are only heated to températures up to45°C, for example.

Throughout the présent description the expression "vaporized superheated water" means "water heated to a 3 012196 température well above 100°C, especially at from 135°C to175°C, preferably at from 140 to 160°C, vaporized orsprayed under a pressure well above atmospheric pressure,especially under a pressure of from 3 to 8 bar, preferablyunder from 3.3 to 6 bar, through a spraying nozzle whichopens into a space under atmospheric pressure and which iscapable of holding the pressure différence between sprayingpressure and atmospheric pressure".

The expressions "particle size d' " and "regularity n"correspond to the "particle size index (d')" and the"uniformity index (n) " according to the International NormISO 2395 which are defined by interpreting sieving trialswhile applying the logarithmic form of the Rosin, Ra.nmlerand Sperling (FRS) équation and using the diagram of baffe.

For carrying ont the présent process it is thus possible tostart witb dry grains of every kind of cereals sucn aswheat, rice, oat, barley o:r millet, or with dry seads ofevery kind of legumes such as pea, bean or lent il, forexample A starting superheated water may be tap water superheatedby steam injection, for example.

The step of surface moistening the grains or seeds bytreating them with vaporized superheated water may becarried out by means of an adéquate screw conveyor and/ormixer of the food industry equipped with adéquate sprayingmeans, for example.

The adéquate screw conveyor and/or mixer may be an

Archimedean screw, a screw or twin screw of a traditionalfood extruder or mixer, or a hollow helical screw, in otherword a hélix, for example. 4 012196

The adéquate spraying means may comprise one or morespraying nozzles capable of holding the pressure différencebetween spraying pressure and atmospheric pressure. Suchnozzles may comprise a cylindrical conduct having acircular opening of relatively small diameter positionedbeneath or within a flow of grains or seeds to be treatedwithin a screw conveyor and/or mixer, for example.

In a preferred case where the screw conveyor and/or mixeris a hollow helical screw or hélix, one or more suchspraying nozzles may be provided for at a down stream endor along the wall of a feeding tube positioned coaxiallywithin the hélix at an upstream end of the hélix, forexample.

The step of impact miJling the surface moistened grains orseeds may be carried ouf by any adéquate impact mill,especially good results being obtainable by using a pinmill, fer example

The step of sieving the mi lied grains or seeds may becarried out by an adéquate sieving machine of the foodindustry such as an air stream classifier, an air jet sieveor a rotating and/or swingable group of superposed sievesor screens.

Preferably, the sieving step is carried out with a sievingmachine at least one sieve of which has a mesh size of from0.2 to 0.3 mm.

It has surprisingly been found that it is possible in thisway to obtain, with a relatively high extraction rate,namely an extraction rate of from 65 to 90%, a flour whichhas a relatively high purity, namely an ash content of from0.73 to 1.75% and which has a relatively well defined 5 012196 granulometry, namely a regularity n of from 1.0 to 3.0 fora particle size d' of from 0.04 to 0.10 mm, for example.

The présent equipment thus comprises means for surface5 moistening cereal grains or legume seeds by treating them with vaporized superheated water, these means beingconnected to an impact mill itself connected to a sievingmachine. 10 The means for surface moistening cereal grains or legume seeds by treating them with vaporized superheated water maycomprise an adéquate screw conveyor and/or mixer of thefood industry equipped with adéquate spraying means, forexample. ’.5

The adéquate screw conveyor and/or mixer may be anrcb\medean screw, a screw or twin screw of a traditional focd extrader or mixer, or a hélix, for exemple- 20 The adéquate spraying means may comprise one or more spraying nozzles capable of holding the pressure différencebetween spraying pressure and atmospheric pressure.

Such nozzles may comprise a cylindrical conduct having a 25 circular opening of relatively small diameter positioned atone or more locations along the screw conveyor, forexample.

In a preferred case where the screw conveyor and/or mixer 30 is a hollow helical screw or hélix, one or more such spraying nozzles may be provided for at a down stream endor along the wall of a feeding tube positioned coaxiallywithin the hélix at an upstream end of the hélix, forexample. 35 012196

The impact mill may be any adéquate impact mill of the foodindustry, namely any impact mill capable of milling surfacemoistened cereal grains or legume seeds, with a relativelyhigh extraction rate, especially an extraction rate of from65 to 90%, to a flour having a relatively high purity,especially an ash content of from 0.73 to 1.75% and arelatively well defined granulometry, especially a regularity n of from 1.0 to 3.0 for a particle size d' offrom 0.04 to 0.10 mm, for example.

An adéquate impact mill may especially be a pin mill, forexample.

Such a mill may especially be capable of milling surfacemoistened soft wheat grains to a flour having an ashcontent of from 0.60 to 0.85, with an extraction rate oftrom 65 to 90%, for example.

Adéquate i.npact mills, especially pin mills are ccrrentlymanufactured and/'or sold by companies such as HosokawaAlpine in Augsburg (DE), Atritor in Gentry (GB),Bauermeister in Norderstedt (DE), Denver in Salq (SE),Jehmlich in Nossen (DE), Kinematica in Littau (CH),Netzsch-Condux in Hanau (DE) or Pallmann in Zweibrücken(DE), for example.

The sieving machine may be any adéquate sieving machine ofthe food industry, namely a sieving machine capable ofeasily separating the bran from the flour obtained bymilling the surface moistened cereal grains or legumeseeds.

An adéquate sieving machine may especially be an air streamclassifier, an air jet sieve or a rotating and/or swingablegroup of superposed sieves or screens, for example. 7 01 2 Ί 9 6

Preferably, at least one sieve of the sieving machine has amesh size of from 0.2 to 0.3 mm.

The equipment according to the présent invention is described in greater detail below with reference to theaccompanying drawing given by way of example and in which:

Figure 1 is an overall schematic représentation of apreferred embodiment of the equipment.

In the preferred embodiment represented in Figure 1, theprésent equipment comprises means 1 for surface moisteningcereal grains or legume seeds by treating them withvaporized superheated water, these means 1 being connectedko an impact mill 2 itself connected to a sieving machine3 .

The means for surface moistening cereal grains or legumeseeds by treating them with vaporized superheated watercomprise a hélix screw conveyor and/or mixer 4 equippedwith spraying means 17.

The spraying means 17 are a spraying nozzle provided for ata down stream end of a feeding tube 5 positioned coaxiallywithin the hélix at an upstream end 6 of the hélixconveyor.

The feeding tube 5 passes through a hollow shaft of a motor 18 driving the hélix 4. The feeding tube 5 is itself fed through a valve 19 with superheated water 20 the température (T) and pressure (p) of which are checked by measuring means 21.

The impact mill 2 is a pin mill. 8 012196

The sieving machine 3 is a group of rotatable and orswingable, superposed sieves 7.

During operation, grains or seeds are fed from a hopper 9into the hélix conveyor 1 through an inlet opening 8provided for at the top of the upstream end 6 of theconveyor.

Superheated water is vaporized into the hélix conveyorthrough the spraying nozzle 17 from which it escapes andexpands at atmospheric pressure in form of a vapor or steamjet which immédiatly condenses on the surface of the grainsor seeds.

The surface moistened grains or seeds are pushed out fromthe conveyor through an outlet opening 10 provided for inthe bottom of a down stream end 11 of the conveyor, thisoutlet opening 10 being connected to the pin mill 2 throughar. inlet pipe 12.

The miiled grains or seeds coming from an outlet pipe 13 ofthe pin mill are fed to a first sieve of the sievingmachine 3 through an inlet pipe 14. Flour comming from thedifferent sieves 7 is collected in a main container 15while bran coming from a last sieve 22 is collected in asecondary container 16.

The process according to the présent invention is describedin greater detail in the examples presented below by way ofillustration and in which the percentages are given byweight.

Example 1

An equipment corresponding to the preferred embodimentrepresented in Figure 1 is used, in which: 9 012196 - the hélix conveyor has a diameter of 80 mm and a lengthof 1600 mm, the hélix itself has an inner diameter of 56 mmand an outer diameter of 76 mm, - the single spraying nozzle is a TG type-UniJet spraying5 opening or nozzle having a flow rate index of 0.3, a nominal opening of 0.51 mm, a free passage of max 0.41 mmin diameter, a flow rate of from 0.25 to 0.28 1/min for aspraying pressure of from 4 to 5 bar, and a dispersionangle of about 50°, 10 - the impact mill is an UPZ 315 type-ALPINE pin mill, and - the sieving machine is a MPAR ROTOSTAR type-BUEHLER"Kleinplansichter" equipped with eight superposed sieves. 300 kg/h of soft wheat grains having a water content of 15 10.55% and an ash content of 1.62% were continuousiy heat

Lreated along the hélix conveyor by 17.5 kg/h of tap waterpreviouslv steam heated to 156°C, ttiis water being sprayedor vaporized under 4.4 bar into the hélix rotating at 513rpin. 20

The surface moistened grains coming out from the hélixconveyor had a moisture content of 17.4% and a températureof 31°C before entering into the pin mill which rotated at8040 rpm. 25

The flour coming out from the mill was conducted onto thesieving machine each sieve of which had a mesh size of 0.20mm. 30 The flour separated from the bran by the sieving machine had a moisture content of 13.27%, an ash content of 0.73%,a mean particle size d' of 0.06 mm, a regularity n of 1.18and it was extracted at a rate or efficiency of 84.9%. 35 This means that the flour thus obtained was extracted at arelatively high rate and had a normal moisture content, a 10 012196 relatively high purity and a relatively well definedgranulometry.

Examples 2 to 5 5

In a way similar to the way disclosed in Example 1,different flours were manufactured from different grainsunder different conditions. 10 The corresponding characteristics of the raw materials,intermediate products, process parameters and floursobtained are shown in table 1 herafter: 11 012196

Table 1

Example No 1 2 3 4 5 grains soft wheat soft wheat durum wheat whole millet soft wheet amount of grains (kg/h) 300 300 372 300 300 water content of grains (%) 10.55 11.69 10.9 10.3 10.11 ash content of grains (%) 1,62 1.59 1.64 1.70 1.61 amount of vaporizedwater (kg/h) 17.5 13.8 6 12 12 water température (CC' 156 153 150 150 150 spraying pressure lûar) 4.4 4.4 3.8 3.8 4.2 hélix speed (rpm) 513 209 213 228 228 moisture content of moistened grains (%) 17.4 15.94 12.92 3 4.07 14 . température of moistened grains (°C) 31 41 39 37 38 pin mill speed (rpm) 8040 8960 8970 8980 8980 mesh size of sieves (mm) 0.20 0.20 0.25 0.25 0.25 moisture content of flour (%) 13.27 12.76 10.44 10.81 11.20 ash content of flour (%) 0.73 0.79 1.24 1.74 0.74 d' (mm) 0.06 0.05 0.10 0.11 0.05 12 012196 n 1.18 1.05 1.46 2.01 1.65 extraction rate (%) 84.9 79.8 87.5 87.7 82.8

Table 1 shows that, as it was the case in Example 1, theflours obtained in Examples 2 to 5 were extracted at a 5 relatively high rate and had a normal moisture content, arelatively high purity and a relatively well definedgranulometry.

Claims (13)

13 012196 Claims

1. A flouring process, comprising the steps of surfacemoistening cereal grains or legume seeds by treating themwith vaporized superheated water, impact milling thesurface moistened grains or seeds and sieving the milledgrains or seeds.

2. A process as claimed in claim 1, wherein the cerealgrains or legume seeds are choosen from a group comprisingwheat, rice, oat, barley and millet or pea, bean andlentil.

3. A process as claimed in claim 1, wherein the superheatedwatel· has a tempe?'ature oi from 135 to 175°C and it isvaporized under a pressure of from 3 to 8 bar.

4. A process as claimed in claim 1, wherein the superiieatedwater has a température of from 140 to 16O°C and it isvaporized under a pressure of from 3.3 to 6 bar.

5. A process as claimed in claim 1, wherein a flour isobtained, with an extraction rate of from 65 to 90%. whichhas an ash content of from 0.73 to 1.75% and a regularity nof from 1.0 to 3.0 for a particle size d1 of 0.04 to 0.10mm.

6. A process as claimed in claim 1, wherein the cerealgrains are soft wheat grains and a soft wheat flour isobtained, with an extraction rate of from 65 to 90%, whichhas an ash content of from 0.60 to 0.85.

7. A flouring equipment, comprising means for surfacemoistening cereal grains or legume seeds by treating themwith vaporized superheated water, these means being 14 012196 connected to an impact mill itself connected to a sievingmachine.

8. An equipment as claimed in claim 7, in which the meansfor surface moistening cereal grains or legume seeds bytreating them with vaporized superheated water comprise ascrew conveyor and/or mixer equipped with spraying means.

9. An equipment as claimed in claim 8, in which the screwconveyor and/or mixer is choosen from a group comprising anArchimedean screw, a screw or twin screw of an extruder ormixer and a hollow helical screw or hélix.

29. An equipment as claimed in claim 8, in which the screwconveyor and/or mixer is a hollow helical screw or hélix, aspraying nozzle being provided for at an upstream end ofthe conveyor, coaxially wj th the hélix.

11. An equipment as claimed in claim 7, in which the impactmill is a pin mill.

12. An equipment as claimed in claim 7, in which thesieving machine is choosen from a group comprising an airstream classifier, an air jet sieve and a rotating and/orswingable group of superposed sieves.

13. An equipment as claimed in claim 7, in which at lastone sieve of the sieving machine has a mesh size of from0.2 to 0.3 mm.