GB2523271A - A conche for use in the manufacture of chocolate - Google Patents

Abstract

A conche 10 comprises a container 11 having an inner surface which is at least partially cylindrical. At least one rotatable shaft 17 is situated inside the container and extends along an axis parallel to the at least partially cylindrical inner surface. At least four shearing elements 19 extend radially from a plurality of axially spaced locations along said shaft towards said inner surface, each shearing element having a proximal end fixed to the shaft and a distal end provided with a shearing tool 21. The shearing elements are substantially uniformly circumferentially spaced around the rotatable shaft and each said shearing tool extends axially by less than about half of the length of the inner surface. At least one of the shearing tools is in the form of a substantially straight blade or wedge extending substantially parallel to the axis of the cylindrical surface. Conventional conches have shearing blades that extend the full axial length of the container. The conche of the present invention provides the shear necessary to liquefy the chocolate masse but uses less energy as the chocolate is not displaced around the conche unnecessarily.

Description

A CONCHE FOR USE IN THE MANUFACTURE OF CHOCOLATE

TECHNICAL FIELD.

The present invention relates to a conche fir use in the manufacture of chocolate. More particularly, the present invention relates to a conche which provides significant improvements in couching efficiency in terms of both time and energy consumption.

BACKGROIJNI) OF THE INVENTION A conche is used within the chocolate manufacthring inclistry to provide a means of vigorously mixing solid partieulates of chocolate with liquid fat ingredients so as to provide a smooth and flowing liquid chocolate. in the conching process, the solid particles are deagglomerated and individually coated with the fat phase. Evaporation of water during conching reduces the water content of the chocolate to the desired low level, for example less than about 1%. In addition to developing the texture of the chocolate, conching also improves the final flavour of the chocolate. This is thought to be due to loss of undesirable, volatile flavour components during couching.

The eonching process typically involves several different stages The starting material is a chocolate masse which has iypici1y been processed in a roll refiner or a hammer mill before eonehing. This masse contains a substantial amount of the fat present in the tina chocolate composdion hut the masse has a solid, crumbly paste or poder texture because of agglomeration of the solid particks, and because most of the surfaces of the non-tat sohd arc hcshly bioken and uncoated by tat The initial stage ot corehing is therefore commonly efened to a, the diy-ptiase the conche opetates, agglomerates of solid particles are broken down and the combination of rising temperature and inoement of the conil.nned rnatcnals piomotes coating of tue particles vtitli the flit At this stage moisture £ easily lost from the mixture, prouded that the conche is suitably ventilated. (ertain undesirable flavours may also he removed from the chocolate in the fonn of volatiles as the temperature increases.

In a sccond stage, sometimes referred to as the pasty-phase, the pasty chocolate becomes less viscous and the flavours are developed by shearing and thermal effects. The viscosity approaches a final, steady-state, or plateau value I he final viscosity is retated to the amount of shear or work that can be put into the chocolate, in a final stage, liquid fat and emulsifier may be added to the conche, This liquid-phase conching stage, which is relatively short, mixes in the final ingredients and allows the viscosity to stabilize, The conehing process requires the input of energy in the form of meclurnica I energy to drive the mixing and shearing elements of the conche. This mechanical energy is converted into thermal energy due to friction and shear in the chocolate, thereby heating the chocolate kddmonal heating anther cooling may he provided by suitaHe heati g and cooling elements, for example a heat exchanger in the wall of the conche.

Previous conches in the art consume a great deal of energy. Much of this energy is "wastcd' in displacing the ingredients around the conehe, with little being applied to the ingredients in the form of shear energy. As a result of this, previous conches in the art are required to operate for any thing, from 4 to 24 hours in order to achieve a free flowing liquid chocolate. These long conching times result in a large amount of energy consumption, which is costly to the chocolate manufhcturei' and also mcans that asset requirements arc greater as each machine can produce only a small number of batches of chocolate over a 24 hour period.

A further difficulty can arise because the conches are driven by electric motors. For a fixed rotation speed, the electric cm-rent drawn by these motors increases with increasing viscosity of the chocolate masse, since a higher torque is needed to move the mixing elements through a more viscous massc. There may be further fluctuations mi torque caused by the movement of the chocolate masse. However, there is a maximum current that the motors can tolerate, i'his means the motors must he operated most of the time at less than optimum power in order to avoid current surges that will result in automatic shutdon of the motors. This is one of the reasons why existing conches are relatively inefficient, in traditional couching the shear energy input fails as the chocolate becomes thinner and it is necessary to increase the shear rate to address this problem 10 increase the shear tate the speed of the mixing elements must be met eased or alterratively, the mtxmng elements themselves can be changed to decrease the gap between the mixing elements md the wall Aftei the viscosity has reached eqrnhbnurn, the chocoate becomes veiy thin and 1t is difficult to apply any furthei sneailng energy to the ehocolak There is thus a need in the art for improved conches which provide a more efficient application of energy in the form of shear energy to the chocolate mixture, resulting in less eaergy being lost in displacing the mixture inside the conche By improving the efficiency of the eonche in this way, overall energy consumption may be reduced leading 1 5 to reduced costs. Additionally, the operation time of the conche may be lowered whilst maintaining the quality and rheological properties of the chocolate. [bk is of benefit to chocolate manufacturers as it leads to reduced asset requirements, since each conehe can produce a greater mirnher of batches of chocolate in a given period. It is therefore an object of the present invention to provide a conche with improved efficiency over previous conches in the art.

DE-A-3918813 discloses a classic "elover4eaf' conehe consisting of a container comprising three parallel chambers and mixing tools disposed in each of the chambers rotating on driven shafts.

US-A-541 9635 discloses a machine for use in the treatment of chocolate paste cornpns ng a n ixrng trough with an inner surlacc that is at leasi partially cyhndncal, paddle shaped treating elements extending radially from at lcast one treatment rotor, and additionally comprising feeding means extending into said trough from a ocation at said inner surface comprising a helical feeding element and a motor means for driving said feeding element in sur h a way as to transport chocolate paste away from said porfln of the inner surface.

DEA3403 155 discloses a conche comprising a trough in which are mounted two rotator shafts each situated in erie trough section, said shafts rotatable about their axes and arranged such that the outer surfhccs each face one another, Each rotor comprises pasting tools with creaming elements extending along the length of the rotator shaft, wherein at least some of the creaming elements are positioned at different distimees from at least one torn! axis os er the axial length of the rotors, ot said eteaming elements are positioned at an angle relative to at least one rotator axis GB-A-1261909 describes a three-stage conche. Each stage has multiple mixing paddles arranged on rotating shafts. All of the paddles are helically inclincd so as to impart lateral movement on the chocolate mixtae LS-Ar36632 dcsuihcs anotbei mu]1it4ge conche iavtng anous dffferen chocolate mixing blades disposed around the rotating shafts of the each stage.

US-A-6 129008 describes a ehccoiate conehe having conching tools extending for the whole length of the conche, with intermpdons.

GB-.A-2302494 describes another conche having a plurality of short helical blades spaced around the rotation shaft. The reference is mainly concerned with adjusting the rotation speed to the chocolate viscosity so as to achieve a constant power requirement.

US-*A-57071 45 describes a eonche having a plurality of "ploughshare" mixing tools mounted on the rotating shaft. These fluxing tools can only be rotated in one direction, and will result in relatively inefficient conching since they displace large amounts of the chocolate masse laterally telatne 1o the amount of chucoate masse passing between the tool and the mde ot the con e housing.

EPA-07 ii SOS describes a continuous chocolate conche of the turbomixer 1pe which arrarge the refined chocolate paste in a thin, dynamic layer which flows in contact with au internal wall 34) of the turbomixer, This represents a radically difftrent solution to the problem of achieving rapid conching.

SUMMARY Of' THE INVENTION

The object of the present invention is to provide a conche suitable for use in the manufacture of chocolate which exhibits improved efficiency compared to conches in the art.

The present invention provides a conche comprising a container having an inner surface which is at least partially cylindrical; at least one rotatable shaft situated inside said coctaiacr extending along an axis patallel to said at least partially cylindrical inner sm face and at least tour shearing elements extending radially from a pluiahty of axially spaced locations along said shaft towards said inner surface, each said shearing element having a proximal end fixed to said shaft and a distal end provided with a shearing tool, wherein said shearing elements arc substantially uniformity eireumferentially spaced around said rotatable shaft and each said shearing tool cxtends axially by less than about half of the length of the inner surface, and wherein at least one of said shearing tools is in the tbnn of a substantially straight blade or wedge extending substantially parallel to the axis of the cylindrical surface Thus, the conche according to the invention differs from prior art conches that have relatively large shearing tools (blades) extending along the fall length of the trougit In the present invention, the shearing blade is split into a number of relatively short tools that are cucurrfeitnt1ally spaced arourd the shalt Lath tool extends ouilv a relatnely short distance axially along the inner surface. In this context, the term "axially" refers to the direction of the principal axis of the cylindrical surface and of the rotatable shaft.

Thus, axially adjacent blades are circuinferentially spaced apart on the shaft. This split blade design exhibits more consistent input of shear energy to the chocolate mixture, arid more rapid reduction in viscosity of the chocolate masse. This is thought to he because a larger fraction of the mechanical energy supplied to the shaft is used to produce shear in the mixtuit, and a smaller tracuon of the mechankal cneigy is wasted in s.mply displacing the mixture than in previously known conches.

The container may he oriented with its axis substantially vertical, or with. its axis substantially horizontal. For containers of the present invention which are arranged horizontally, the conche container is closed at the ends by walls. For containers of the present invention wherein the contamer is arranged vertically, the container is closed at its lower end by a wail.

The container may comprise a single fully cylindrical surface an-anged with the axis of S said cylindrical surface oriented substantially vertical or horizontal. More suitably. the containir may comprise a plurality of intersecting innet partial cylindrical sw faces In conches of the present rnvennon compusug a houzontwly oriented container, a plurality of uoughs may be overlapped so as to form a single container such that the width of the container is less inan tne combined diameters of each of the individual troughs, as in a conventional clover-leaf conche. In conches of the present invention comprising a vertically oriented container, a plurality of partially cylindrical smiaces may be overlapped so as to fonn a single container closed at the lower end by a wall. It will he app ccia;ed that cht, respc ctive central axe' of the ov erlaoping partial e inditeal inner surfaces arc normally substantially parallel.

The said number of overlapping internal cylindrical surfaces may be of the same size or varying in size relative to neighbouring internal cylindrical surfaces. Suitably, the present invention may comprise three partially cylindrical inner surfaces, o1flionaliy wherein the diameter of the central partially cylindrical inner surface is greater than those of the two neighbouring partially cylindrical inner surfaces.

The number of rotatable shafts may be equal to the number of overlapping internal cylindrical surfaces, Suitably, each of the rotatable shafts is equipped with shearing elements in accordance with the insentrnn The container may be held by side walls which act as a stand. Suitably, the conche may comprise a heat exchanger such as a water jacket in the container wall to control the temperature of the chocolate inside the conche, The conche comprises at least one rotatable shaft situated inside said container extending along an axis parallel to said at least partially cylindrical inner surface, Suitably, said axis is coaxial with the cylindrical inner surface. Suitably, the conche comprises two or more rotatable shafts, typically one for each of the internal cylindrical surfaces of the container. Suitably the conche may comprise 2, 3, 4, 5, or 6 rotatable shafts. Normally the at least one rotatable shaft extends along the full length of the container, Suitably the at least one rotatable shaft andior the container imier surface may be from about 40cm to about 300cm long, for example fioni about 100cm to about 250cm long in pnulucuon conches. Each rotating shaft of the present invention may rotate about an axis parallel to said at least partially cyLudrical inner surGice, which may be a honzonLj axis or a vertical axis depending cii the conche u'nstruction, hut most suital4% is horvontal For embodiments of the invention comprising at least two rotatable shafts, each rotatable 1 0 shaft may rotate in the opposite direction relatisc to the direction of rotation ot one or more neighbouring rotatable shafts. The shearing elements are disposed around the respective shafts (and the rotation of the shafts is synchronised) so that the shafts can counter4otate without bringing hearng tools on adaLent shaft', into collision [hi',, for example, the shearing elements at the same longitudinal positions on adjacent shafts are suuably offset by at least 60 degiees, for example about 90 degrees The present invention may comprise three rotatable shafts spaced apart from one another where the conche is a clover-leaf condhe wherein the container and rotatable shafts are onenttd sub'taitially vcrlical or uhstantiaIly.ioriionta1 The conche of the present invention comprises at least four shearing elements extending radially outwardly from a plurality o-f axially spaced locations along said shaft towards said inner surface, each said shearing element having a proximal end fixed to said shaft and a distal end provided with a shearing tool, wherein said shearing elements are substantially uniformly cireumferentially spaced around said rotatable shaft and each said shearing tool extends in a direction parallel to the axis of the at least partially cylindrical inner surface by less than about half of the length of the inner surface..

Each shearing element has a proximal end fixed to the at least one rotatable shaft and a distal end provided with a shearing tool, The shearing elements extend radially from a plurality of axially spaced locations along said at least one shaft towards said inner surface, and suitably said locations are positioned at regular intervals along the at least one rotatable shaft so as to ensure that the tools pass over the entire at least partial cylindrical inner surface of the container.

The at least one rotatable shaft may he provided with between 4 and 50 shearing elements, for example between about 10 and about 25 shearing elements, Suitably the at least one rotatable shaft may be piovided with 4 5,6 7, 8,9, 10, 11, 2, 13, 14 15, 16, 17, 1 8, 19, or 20 shearing elements. The at least one rotatable shaft suitably may comprise at least 8 shearirg elernerts, m.sre suitably fiom about 10 to about 20 shcarmg elements.

Swtably said sheanng elements may be arranged in opposed pairs spaced along said rotatable shaft, optionally whereby the shearing tools each extend in a direction parallel to the axis of the at least partially cylindrical inner surface to a length. of about 2L/N or more, where L is the length of said container and N is the total number of shearing elements fixed to the rotatable shaft. In any event, axiafly adjacent shearing tools suitably overlap or adjoin along the axis of the container so as to ensure that substantially the whole of the inside surface of the container is scraped by the shearing tools.

Suitably the shearing elements are arranged substantially helically around the at least one rotatable shaft, That is to say. successive shearing elements (or opposed pairs of shearing elements) are circumferentially spaced at successively increasing angles along the shaft. An advantage of the present invention having multiple shearing tools disposed along a helical path is that, unlike a continuous helical shearing tool, the split olades do not waste energy pumping the chocolate axially along the container.

It will he appreciated that in embodiments of the present invention comprising two or more rotatable shafts, the number of shearing elements fixed to each shaft may be different, or the same.

Each shearing element cornpr1ses one or more arms etendmg radial'y (1 e suitably substantially perpendicularly) from the at least one rotatable shaft. For conches of the

S

present invention comprising two or more rotatable shafts associated with respective partial cylindrical inner surfaces having different radii, the length of the at least four shearing elements on a first rotatable shaft may differ from the length of the at least four shearing elements on a neighbouring rotatable shaft. The rotatable shafts are syuchronized, and the shearing elements on neighbouring shafts are oriented, so that the shafts can rotate or counter-rotate with the shearing elements on adjacent rotatable shafts inc1ung but riot colliding Tnis has th lurther advantage that bu'ld-up of solids on each shaft is cleared by the shearing elements on an adjacent shaft as the shafts i date The length of some or all of the arms may be adjustable to vary the spacing between the shearing tools and the inside of the conche housing. Suitably, the arms are relatively narrow to minimize the energy required to drive the arms through the chocolate masse relative to the energy delivered to the shearing tools. For example, the arms may have a cross sectional area less than about 10% of the cross-sectional area (plan view) of the 1 5 shearing tools. Suitably, the arms have a mean cross-sectional area less than about 10cm2. for example less than about 5cm2, A shearing tool is provided at the distal end of each of the shearing elements. The shearing tool may be attached to the arm by suitable fixing elements such as screws, or it may bc in one picce itt the arm Suitably, the shearing tool is located in close proximity to the at least partially cylindrical inner surface in order to shear the chocolate mixture between said inner surface arid the surface of the shearing tool. For example, the minimum spacing between the shearing tool and the inner surface may be less than 25mm, suitably from about 1mm to about 20mm, more suitably from about 15mm to about 5mm, for example 1,2,3,4, 5,6,7,8,9, 10, ii, 12, 13, 14, 15, 16, 17, 18, 19 or 20mm.

The shearing tool extends for less than half the length of the inner surface in a direction parallel to the inner surface, Suitably, each said shearing tool extends along a distance of from about 3% to about 25% of the length of the inner surface, for exampie from about 4% to about 20% of the length of the inner surface. in typical embodiments, each shearing tool extends from about 5cm to about 50cm along the inner surface in the direction of the axis, for example from about 10cm to about 25cm. The use of multiple, short shearing tools cireumferentially spaced around the shaft has been found to result iii much more rapid coaching of the chocolate masse and reduced overall energy consumption. It is thought that this is because the split-blade shearing tools impart relatively more shearing energy and less displacement energy to the chocolate masse than conventional tools that extend along the whole length of the container..A further reduetio in displacement energy is achic% ed by using tools that &c substantially symm-3trical (mmnor syrnnietiy) about a plant intersecting the middle of the tool perpendicular to the said axis of the container, Suitably, the entire shearing element has the said substantial mirror symmetry. Suitably, the cross-sectional profile of the shearing tool is substantially constant along the length of the shearing tool in the longitudinal direction. Suitably, substantially all of the shearing elements have this symmetry 1 his slructme rmnimises pumping of the chocolate masse along the axis by the tools.

At least one shearing too! is substantially in the form of a substantially straight blade or wedge extending substantially parallel to the axis of the cylindrical surface. The term blade ot wedge" re*rs to a shape havag opposing straight edges on opposite sides of the tool, each edge extending substantially parallel to the axis of the cylindrical surface.

Suitably, the opposing straight edges are of substantially equal length, whereby the ends of the tool may be perpendicular to the straight edges to minimize longitudinal displacement of the chocolate masse as the tool is rotated. The mean thickness of the tool (measured radially from the axis of rotation) is suitably substantially less than the length of the straight edges, for example it may be less than about 5cm, more suitably less than about 2cm, The use of a relatively thin blade tool also helps to minimize rotational displacement of the chocolate masse as the tool is rotated. Likewise, unnecessary displacement of the chocolate masse is avoided by using a straight-edged tool that does not comprise a gui-face that would displace the chocolate masse longitudnaIly as flit tool is iotated such as a helical surtace Suitably, substantially all major surfaces of the tool(s) are oriented perpendicular or parallel to the plane defined by (i.e. perpendicular to) the axis of rotation of the eonehe in order to minimize longitudinal displacement of the chocolate masse during conehing. The term "major surface" refers to any surface making up more than about 10% of the total surfitce area of the tool. In this way, the bulk of the energy required to rotate the tool through the chocolate is directed to shearing (or elongational flow mixing) of the chocolate masse by the tool.

The opposed straight edges also allow the tool to be rotated usefully in either direction.

Suitably, the spacing and and/or the angle of attack (angle relative to the tangent at the housing) of the first edge is different from that/those at the second edge, whereby different relative amounts of longitudinal mixing sersus shear rmx1ng are achieved depeviding on the direction of rotation as explained firther belo The shearing tool is arranged with. its principal axis substantially parallel to the axis of i otation and substantially porpendieulai to the one in more arms ot each shearing element, such that, during rotation of the at least one shaft, the shearing tool displaces the chocolate. masse in directions perpendicular to the axis of rotation, with minimum displacement of the chocolate masse along the axis of rotation.

In certain embodiments, the shearing tool may be substantially wedge shaped, whereby the principal axis of the wedge shape is substantially parallel to the is of the conche.

In other embodiments, the shearing tool may be in the form of a blade having an outwardly curved or angled surface facing the container irmer wall.in these and other embodiments, the shearing tool comprises a shearing surface pointing towards the at least partially cylindrical inner surface wherein said shearing surface may be inclined at an angle of from I to 45 degrees re!ative to the tangent of the at least partially cylindrical inner surthce, more suitably from 5 to 35 degrees, even more suitably from 10 to 25 degtes relative to the tangent to the cylindrical surface under the surface.

Mine suitably, the shearmg tool may compnse tlist tnd second she?ring surfaces facmg towards said inner surface of the container and adjacent to said first and second edges, respectively. Suitably, the first shearing surface may be inclined at an angle of between I and 40 degrees relative to the tangent of said partially cylindrical inner surtitee when viewed in cross-section transverse to the axis of rotation, preferably between 1 and 30 degrees, more preferably between 5 and 15 degrees. The second shearing surface may be inclined at an angle of between 10 and 55 degrees, preferably 15 and 50 degrees, more preferably 20 and 45 dcgrcc relatiw to thc tanacnt of ad partiady cylindrical 1inei surface. Suitably, the angle of the second surface relative to the tangent may he greater than the angle of the first surface relative to the tangent. It will be appreciated that the above shearing surfaces need not be planar, but suitably they are substantially planar. It will be appreciated that the first and second shearing surfaces above may be regton of a substantially continuous, curved or angled surface of the tool facing radially outwardly towards the cylinder wall. The tool may he attached to its supporting arm(s) by a coupling that allows adjustment of the angle between the tool and the cylinder wail, i.e. tilting of the tool to optimise the angles between the tool edge surfaces and the wall. The coupling or the arm(s) may additionally or alternatively be adjustable to vary the spacing between the tool and the cylinder wall.

Suitably, the shearing tool is suitably not symmetrical about the plane encompassing the axis of rotation and the central longitudinal axis of the tool, whereby rotating the tool in different directions applies different amounts and/or type of shear to the chocolate masse in the eortche.

Suitably, the shearing tool may provide a surface suitable to apply elongational (longitudinal) flow mixing to the chocolate when the rotatable shall rotates in a first direction, Elongational flow mixing takes place when the chocolate mixture is forced through a constriction. In the conches of the invention, such elongational flow mixing is athieved by fowing the nuxture througn a conuictton formed bet'.een the sheaung tool and the container wall, Such mixing is especially effective for deagglonierating solid particles and coating the solid particles with the fat phase to lower the viscosity of the mixture, In a later stage of the conehing process where elongational flow mixing of the ingredients is no longer preferred, the direction of rotation of the shaft(s) may be reversed and the shearing tool. may provide a surface suitable for scraping the inside wall of the container and lix tumbling and mixing of the chocolate mixture. The shearing tool may also cornpn'.e a flat surface perpenthtular to Lhc tangent of the at least partially cylindrical surface and opposite to the blade like edge, which aids in the movement and tumbling of the chocolate mixture when the direction of rotation of the shaft is reversed.

The abovedescribed geometries arid features of the shearing tool are suitably present, either alone or in combinations of two or more of the features, in at least one of the shearing tools, more suitably at least two of the shearing tools, and most suitably all of the shearing tools.

In certain embodiments, the shearing elements on each shaft are arranged in groups (hereinafter called shearing units). Suitably, the shearing units are identical repeating groups of shearing elements.

In embodiments, the present invention comprises two or more such shearing units fixed iS to the an at least one rotatable shalt Suitahy, the tt o or more shearing umts fixed to the at least one rotatable shaft each comprises the same number of shearing elements.

Even more suitably one or more shearing elements of a first shearing unit may each be circumferentially located at the same position around said rotatable shaft as one or more partner shearing elements of a second or flirt er shearing unit fixed to the same said shaft.

More suitably two shearing units are fixed to the same said at least one rotatable shaft, wherein a first unit comprising at least 4 shearing elements is fixed to a first portion of the shaft and a second unit comprising at least 4 shearing elements is fixed to a second porbon of said shat Even more su tabiy.. the number of shearing e'cments in each if the two shearing units is equal. When said at least one rotatable shaft is viewed in longitudinal cross section, one or more shearing elements comprising the first shearing unit may cach overlap with at least one partner shearing element comprising the second shearmg unit fixed at a distance along the rotatable shaft, wherein s&d parinu shearing elements are elements that arc circumferentiafly located at the same position around the same rotatable shaft.

For example, 20 shearing ekments, comprised of two shearing units each having 10 shearing elements, may he arranged along the sarrie at least one rotatable shaft. Suitably, when said rotatable shall i viewed in longitudinal cross section, only 10 shcanng elements may be observed since each shearing element of the first shearing unit has a partner sheaung element eompnsng the secc'nd shearrng unit circurnferenLally positioned at the same location around the rotatable shaft and paeed furthei along me rotatable shaft Mote suitaoly saui 20 shearing e1erncnt are arranged in opposed pairs at about 36 degree inteivah cirLumfetentlall) around the intatable shaft Shearing elements of said at Least one shearing unit may he individually fixed to unique positions spaced along the rotatable shaft, such that no two shearing elements are fixed at the same distance along any one rotatable shall. Alternatively, the shearing elements of said at least one shearing unit may be arranged in opposed pairs spaced along said at least one rotatable shaft. Suitably, a first shearing element of each opposed pair is fixed at a certain distance along the rotatable shaft and the second shearing element of each pair is positioned at 180 degrees cireumferentially around the same rotatable shaft relative to the position of the first shearing element of each pair, and is fixed at said same distance along said rotatable shaft. It is to he appreciated that in conches according to the present invention comprising two or more rotatable shafts, the configuration of the at least 4 shearing elements fixed to a first rotatable shaft may differ from that of the at least four shearing elements fixed to a neighbouring rotatable shaft.

Suitably, the shearing elements of the at least one shearing unit may be helically arranged around the at least one rotatable shaft such that starting from a first shearing element in said shearing unit, each subsequent shearing element iii the order of which they are fixed to the rotatable shaft, is circumferentially positioned at intervals of about 360/n degrees, where a is the number of shearing elements in said shearing unit, around said at least one rotatable shaft in a clockwise direction relative to the previous shearing element fixed to the shaft, Alternatively a helical arrangement of shearing elements of the at least one shearing unit may be achieved by starting from a first shearing element in said shearing unit, and positioning each subsequent shearing element in the order of which they arc fixed along the rotatable shaft, at intervals of about 360/n degrees, where n is the number of shearing elements in said shearing unit. around said at least one rotatable shaft in an artticiock.wise direction relative to the previous shearing element fixed to the shalL Suitably said shearing elements arranged helically may be arranged individually along the rotatable shalt or in opposed pairs.

The shearing elements of the at least one shearing unit are substantiaHy unifOrmly circwnferentially s)aced around the at least one rotaabI shall, such that when viewed in longitudinal cross section, the angle defined by any set of two adjacent shearing elements varies by no more than 15 degrees from the angle defined by any second set of two ad2ccnt shcarrng elements More surahl, the Theanng eemcrfls may be circumferentially spaced around the at least one rotatable shaft at intervals in degrees of about 360/n where n is the number of' shearing elements in said a-i least one shearing unit either arrangee individually or m opposed pads Suitably, a sheanug unit may consist of 4 shearing elements individually spaced along the rotatable shall and an'anged at about 90 degree intervals around said shaft, More suitably, a shearing unit may consist of 10 shearing elements spaced at about 36 degree intervals around said rotatable shaft either arranged individually or in opposed pairs.

Suitably, Thr embodiments of the present invention comprising two or more rotatable shafts, each shearing element on a fit -otatable shoP ma he oriented at an angle tfor example about 90 degrees) relative to the shearing element at the same axial position on the neighbouring shaft(s), such that collision of the shearing tools of adjacent shafts is avoided. This is a further advantage of the split blade shearing tool configuration according o the present mnenlion Suitable materials for use in conches according to the present invention are any foodS safe materials such as stainless steel. Such suitable materials must also he able to withstand increases in temperature and forces such as those generated inside the conche by shearing. is

In a thither aspect, the present invention provides a method for the manufacture of a chocolate comprising couching milled chocolate ingredients in a conche according to the present invention.

[he concbing step in this aspect of the invention may rep cc tie concFirg step of any conventional choco ate n'anufactuing plOLe&, fbr example any of the pr.Lcsses described in "Choc ate Cocoa and Confectioney", Bernard Minifie, 3rd Ecitun, Spri%er-Verlah (1989), Chapter 5 "Chocolate Manufacture', the entire content ol whlLh is incorporated herein by reference The milled choco ak ingrcdiens may, for examp e, compfse, cocoa solids, suga, milk solids, and milk crumb Ft rther ingredients added in the conch ng step rna include, for xampie. emuiCtiers cocoa buffer, and othcr fats.

Othr steps of he chocoate mant factoring process accordir g to this as ect aay be any of the conventiona steps as dcscribcd by Nhnifie and well known n the art 1 5 Suitably the method according to the present invention may result in improvements in terms of energy-efficiency or time-efficiency of at least 10% relative to a standard concie. Suitably a conche according to the present invention may result in improvements in terms of energy-efficiency or time-efficiency of 10, 15, 20, 25,30, 35, -10, 45, 50, 55, 60, 65, 70, or 75 % relative to a standard conchc in the arL More suitably, a conche aecorclirg to the present invention may resuk in improvements in efficiency of from about 10% to about 60%, more suitably about 15% to about 40%, relative to a standard conche. The term "standard conche" refers to a conehe of the same size and shape but having mixing tools each extending for the full iength of the eontainei DESCRUTION OF FIGURES.

Specific embodiments of the present invention will now be described fin-ther, with reference to the accompanying drawings. in which: Figure 1 illustrates a schematic transverse cross-section through a conventional conche known in the art Figure 2 illustrates a schematic transverse cross-section through a conche of the present invention, Figure 3 illustrates a de ai side view of a shearin elen'en of the pricr in conchc ci Fig. I Figure 4 ilh.strates a chematie perspective view with the top of the housing cut way.

a conch of the pr sent unention.

ligure 5 iflu'trates a detal side view f a sh aring element of the conehe according to the mvei tion; Figure 6 illustrates the results of experimen i tests companng viscosity with total conching time for a e icco late made usng both a previoua conche n the art aid a eon lie accord ng o the present invent'o Figure 7 i lustrates fit results of experimenta terts con pirin yield with total c nch ng tIme for a chocolat made using both a previous conche in the art and a conche according o the prcseit invent rn Figure 8 illusttatcs the results of experimen I tests corn anng viscosdy with total ci ergv consumption for a choco ate made usm& 1 oi a p cvious cone. e tn tie art and a c inche acLording to the present inventiot Figure 9 illustra es the results of experimental teats comparing y cM with total energy consumpti ri for a chocolate made us ng both a pievious coiche n the ar and a conche aeco ding o the present invent on.

DFFAT..LED DESCRWTION OF THE INVENTION Figi illustrates a typical conche known in the art, for example the Frisse DtJC-6 clover-leaf conche used for the comparative experiments below. The conehe I comprises a container 2 in the fhrrn of three axially intersecting cylinders 3 with three rotatable shafts 4, 5 each associated with a respective partial cylindrical inner surface. Disposed on each shalt 4, 5 is an opposed pair of shearmg clcncnts 6, 7 Eeeh shearing elemcn 6, 7 is provided at its outside edge with a shearing tool 8 which extends longitudinally along the full length of the container 2. Each rotatable shaft 4, 5 also has at least one pair of mixing vanes 9 attached to each shaft 4, 5. The shearing elements 6 attached to the central rotating shaft 4 are longer than those shearing elements 7 fixed to neighbouring rotatable thafts 5, because of the larger radius of the central cylindrical inlier surface of the conche 1. The rotation of the shafts is synchronized so that the shearing elements on adjacent shafts are out of phase and do not collide during rotation.

Fig 3 illu'trates a cross-section e\k of one of the sheanng elements 7 of Fig 1 The shearing element 6 comprises a shearing tool 8 at the distal end of the shearing element.

l ne snearmg clement 6 also comprises an arm 50 having a proximal end (not shown) fixed to the central cotatahle shaft of the conche The sheaing tool S is substantially wedge-shaped and comprises first and seond shearing surfaces 51,52, respecthely facing towards the at least partially cylindncal inner surface of the contarnei Ihe first shearing surface 51 is inclined at a first angle relative to the tangent of the partially cylindrical inner surface. The first shearing surface tapers to a blade-like edge 53 adjacent to the inner surface. The minimum distance between the first shearing surthee 51 anil the inside wall of the housing is suitably 1-2cm. The shearing tool 8 additionally comprises a second shearing surtace 52 inclined at a second angle relative to the tangent of the partially cylindrical inner surface such that the second angle is greater than the first angle. The shearing elements depickd in Fig. 3 may be moved in either a clockwise or anticlockwise direction relative to the at least partially cylindrical inner surface. The direction shown in Fig. 3 is the direction used for the pasty phase of couching, whereby the masse is smeared between the tool and the housing wall to achieve maximum 2.0 elongational flow mixing. The direction of rotation is reversed for the final, liquid stage of conching in order to maximize turbulent mixing of the liquid.

Figs 2 and 4 illustrate an exemplary wnehe 10 01 the present invention uewcd in longitudinal cross section. The conche 10 comprises a container 11 having an inner surface 12 which is at least partially cylindrical wherein said container 11 comprises three troughs 13, 14, 15 wherein said troughs overlap 16 to form a container 11 in similar fashion to the conventional clover-leaf conche of Fig. I. The conche 10 comprises a cntial iotataolc shaft 17 and t\%o ne'ghhouring totataHe shafts 18 situated inside the container ii arid extending along an axis parallel t said at least partially cylindrical inner surface 12. Fixed to the central rotatable shaft 17 are shearing elements 19 according to the present invention. Fixed to the neighbouring rotatable shafts 1 8 are shearing elements 20 according to the present invention wherein said shearing elements 20 are shorter than the shearing elements 1 9 fixed to ilie central shall 7 due to the different radius of the outer curved inner surthees, The shearing elements 19, 20 are each provided at their respective distal ends with a shearing tool 21.

At any one time the central rotatable shaft 17 rotates in the opposite direction to ncighborrng otatahle shafts 1 8 such that the cential snaft of tne conche nny prucipally in a clokise dnectior. whilst the neighoourrng shafts pnneipally rotate in an antFclockwce direction 1 lie conehe is eontructerl so tnat the direction of rotion of each shaft may be reversed. Suitably, the conehe is provided with one or more electric motors to drive the shafts, and the direction of rotation can be reversed.

Each iotatahle shaft 17, 18 is provided with two shearing units spaced along the shall Each unit has ten shearing elements lL20 arranged iii five opposed pairs and spaced along the otatahle snaIls 17, 18 The ten heanng clemLnts 19 20 of each utut aic thus uniformly circumferentially spaced at 36 degree intervals around the rotatable shafts 17, 18. T1e distance between a neighbouring rotatable shaft 18 and the central rotatable shaft 17 is less than the combined lengths of two corresponding shearing elements 19 and 20.

Accordingly, shearing elements 19, 20 at equivalent axial positions on neighbouring rotatable shafts 17, 18 are angularly offset so that the shafis can rotate without collision of the shearing tools.

Referring to Fig. 5, the shearing elements each comprise an arm in the form of iwo spaced-apart metal bars 40,4 1. The arm is attached at its first end to the drive shaft through a coupling 43 that allows the arm to be rotated about its axis to align the shearing tool accurately parallel to the axis of the conche. The bars 40,41 have a small crosssection so as to minimize displacement of the chocolate masse by the arm during rotation. The second end of the arm is attached to the shearing tool 44 through coupling 47. Suitably, coupling 47 that allows the angle of attack of the shearing tool to be adjusted as shown in broken line in Fig, 5. Suitably, the coupling 47 is titrtber adapted to allow the spaemg oltbc shearing tool 1mm the housing wall to he adjusted The shearing tool 44 is substantially a short section of the shearing tool shown in Fig. 3.

It comprises first 45 and second 46 shearing surfaces facing towards the at least partially cylmdiical inner ur{ae of' the onLuner Suitably the first surface 45 may be inclined at an angle relative to the tangent of the at least partially cylindrical sm-face wherein said angIe is smaller than the angle at which the second surface 46 is inclined relative to the same tangent. The blade-like edge of surface 45 points in the direction of rotation of the shaft during the maw conching stage duung which shear enelgy is apphcd to the chocolate,

EXAMPLES

In the experiments outlined below, a 60 kg capacity.Frisse DUC conehe similar to that illustrated in Fig.! was modified foflowing detailed design work and bespoke manufacturing of the required hladt components to cornprie three rotatable shafts each fitted with ten individual blades, wherein the blades are arranged in five opposed pairs spaced along the shaft such that individual blades are uniformly cireumferentially spaced by 36 degrees around the shaft, and each blade (shearing tool) extends along one fifth of the length of the shaft inside the conehe. In other words, a conche as shown in Figs. 2 and 4, hut with only a si.rgle I. 04,lade shearing unit per shaft, Studies were carried out to compare this modified split blade design according to the present invention with the original design comprising three rotatable shafts, each shaft fixed to two shearing elements arranged in opposed pairs with a single shearing tool affixed to each shearing element extending longitudmally along the full length of the container.

A series of eonche cycles were performed with both blade configurations using an identical recipe chocolate and the same raw materials, Conche cycles of different duration were performed, and the energy consumption and the resultant rheology of the eocolate were meawed Other impottant tests siren as mobture and (at chcckb \CiC also performed.

A batch of milled chocolate crumb powder was soureed and stored in airtight conditions for the duration of the experiments. This one batch was used for all experiments so that consistency of particle size distribution which significantly impacts chocolate rheology could be guaranteed. Similarly, single batches of cocoa butter, vegetable fat and lecithin were used over the course of the experimeirts, Milk fat was sourced on a day-to-day basis to guarantee freshness. All conche cycles described in this report were perfonned with 45 kg batches.

Both conches of the experiment ere filled and operated according to the te outlined below and in Table 1: 1. Conche warmed to 40 °C 2. Cocoa butter, vegetable fat, milk fat and soya lecithin (shot 1) pre-rnixed in a bucket 3. Conche filled with chocolate crumb (30 kg) and 50% of the fat mixture 4. Conehe mined at 500 rpm for 2 minutes 5, Remainder of chocolate crumb and fat mixture added 6 Conche turned at 500 rpm for 2 minutes 7. Fill procedure complete, automatic program started (table 1) Table I Conehe cycle program overview Step Lime (mm) Speed (rprffl Direction Start 0 1180 Forw,ards Lecithin shot 2 T-12 1180 Forwards Hrd dry-conchc F 0 Stop titaft... tsr" Lecithin shot 3 + T+lO 2360 Backward', vamilin . End T±42 jO Stop

I

A series of experiments were run to compare a previous conche machine in the art, similar to that illustrated in Fig. 1, and the split blade conche machine according to the present invention. Table 2 outlines these experiments. Both the original and the split blade design conches were run with varying dry-conche times (T) of between 43 arid 283 minutes. The wet-eanehe (liquid phase) duration was identical in all experiments (42 minutes) as outlined in Fable I. Table 2 Overview of all experiments with the two key variables Exp J Blade Drv-concte time T (mm) New plit-biade 123 2 New split-blade 123 New split-blade *123 4 >ew split-blade 83 NLw split-blade 43 6 Origiral 123 7 Original 83 8 Original 43 9 Oal On. completion of each conche cycle, a sample of chocolate was taken for rheology analysis using both factory standard equipment and R&D laboratory equipment. Fat and moisture content measurements were also taken using NW equipment. Additionally, the conche cycle data was extracted from the hardware and analysed in order to calculate 1.0 energy consumption figures for each experiment.

A summary of the key results is shown in Table 3

Table 3 Overview of key results Fxp Dry-Energy Energy Total Moist F'it Viseoity (P s) ield (Pa) conehe dry-set-energy ure (%) I timc T coucht onthe (WhIk) (1⁄4,) I ab l ab (mm) Wh/kg) (Whlkg) nnstscmet I. rneat rernetfl has nas specs stress coreetion applied) apphd) Factoiy ab FacEciy Lab 123 837 17 i99' 13 295]42O 14o 180 j200 123 807 I80 13 296 438 Jit J2°±J 3 121 805 170 975 14 296 446 366 207 4 83 5b2 183 745 13 29o 490 464 90 214 43 308 189 497 14 294 6J0 507 263 379 rTT TTTh7 942 TT;;" T 7 8 Mo 170 (86 14 294 637 562 231 326 + t :g 43 26.4 147.1 IA 1294 9:6.39 136.4 Ho 9 253 1b9 164 1854 14 295 62 35 1174:221 This data has then been illustrated graphically in Fig.5 and Fig6 to show the relationship between total eonching time and chocolate rheology (viscosity and yield) for the two conche designs. Similarly, Fig,! and Fig.S illustrate the relationship between energy conunpuon aVid chocolate meology (\tiscoslty and yield) for both the original nd split blade designs. The results can be summarised as follows.

Rheology iw. time analysis Examination of the data obtained from the experiments outlined iii Table 2 revealed the effect of eonching duration on the final chocolate rheology for both blade designs. For the original blade design Figure 5 ind1eates that a minimum couching tme J approximately 210 minutes is required to reach the factory target viscosity. For the split-blade design, a minimum conching time of 1 00 minutes is required to reach the same factory viscosity ti gU, icpicsentmg a 50% tirnc_efheierey impiovcireni Figuic 6 shows a similar percentage time-efficiency improvement, although longer conching times are required in both eases to reach target yield about 20 minutes for the original blade design and 160 minutes thr the split-blade design.

Rheology vs. energy analysis Figure 7 indicates that for the original bade design, a minimum energy input of 120 Wliikg is required to reach the factory target viscosity, For the split-blade design, the target chocolate viscosity is reached with an energy consumption of approximately 60 Wh/kg, representing a 50% energy-efficiency improvement. Figure 8 indicates that the spIitblade design represents an approximate 45% energy-efficiency improvement in order to reach target yield -about 180 WIt/kg for the original blade design and 100 \Vhfkg for the spIitbiade design.

The moisture and fat content results were consistent across all experiments (within the boundaries of the inherent error of the measurement technique). It can therefore be stated with confidence that these parameters do not affect the resu1t Accordingly, at pilot plant scale, it has been shown that a Frisse DUC conche fitted with a novel blade design, which consists of ten individual blades mounted in a uniformly cireumferentially spaced arrangement on each shaft, can deliver chocolate with the desired rheological properties in approximately half the time and with approximately half Inc energy consumption of fhc samc conchc titttd with tiaditiona' single piece blades. Anticipated energyefficiency improvcrnenLs on a factory scale are likely to be in the range of 10% to 40%, given the inherent differences in scale parameters between a pilot plant and factory conche -specifically the far greater material volume to blade surface area ratio of a factory scale machine. Even so, it is expected that significant energy savings can be made by appiyrng Jus tcchnology to a fatory scale system -potentially in the region of 1 5%.

The improvement in energy efficiency is surprising in view of the fact that the cross-section of the blades is similar to that of conventional conches, the only difference being that the blades are split and cfrcurnferentially spaced around the shall, The energy saving h thought to be due at least in part, to reduced energy lost by surple displacement of the chocolate masse.

The above embodiments have been descnted by way of example only Many other cmbo±mcnts falling within the scope of the accompai ymg claims will be appaient to the skilled reader.