MIXING DEVICE AND METHOD

This invention is directed to the mass manufacture of baking mixes, and in. particular to raw crumb baking mixes comprising a base of fresh fat combined with flour to produce a loose mixture of loose separate crumbs to which additional ingredients can be added.

Conventional domestic science commonly identifies three processes for making baked goods: creating a creamed mixture or batter where dry ingredients or eggs are vigorously beaten together with fats oils or fluids; creating a dough by mixing dry ingredients with fats, oils or fluids until they bind together into one solid block; or creating a rubbed-in mixture by combining fresh (as opposed to dried) fat with flour by rubbing the fat and flour together between the thumb and fingertips until a loose crumb mixture is produced. Other ingredients can then be added to this rubbed in mixture.

In response to the demand for fresh part-made goods, which the consumer can finish baking at home, raw creamed mixtures, batters and doughs have been produced in volume.

However, mass-produced raw rubbed-in crumb mixes requiring a base of fresh fat rubbed into flour have not yet been achievable. Attempts at volume production have resulted in emulsifϊcation of the fat and flour mixture, and clogging of the machines.

Manufacturers attempting to solve these problems have resorted to the production of dry cake, muffin, scone and pastry mixes by combining flour with dried fat flakes, or in the case of ready-made crumble mixes, by creating doughs, which are part-baked and then crushed. Neither of these processes satisfactorily replicates the rubbed-in fresh crumb mixtures that can be created by hand in the home kitchen.

The present invention aims to address these problems and provide improvements upon the known devices and methods.

Aspects and embodiments of the invention are set out in the accompanying claims.

In general terms, aspects of the invention comprise producing a rubbed fat and flour mixture on an industrial scale, using the steps of: adding flour to a mixing container; adding fat to the mixing container; mixing the fat and flour using one or more motorised mixing implements or arms; and manipulating or managing the temperature of the mixture, thereby reducing or preventing emulsifϊcation of the mixture.

This enables the successful mass production of raw crumb mixes containing fresh fat, to which additional ingredients can then be added to produce fresh crumb baking mixes from which the consumer can make cakes, scones, crumbles, pastries, muffins, biscuits and a variety of other baked goods in the home.

The inventor has recognised that such raw crumb mixes require fat combined with flour, within which the fat content is high - commonly 30% or more. This high fat content, coupled with the heat generated by the action of high-volume processing, makes the molecular structure of the fat unstable. Solid fats used in baking are comprised of fat globules, solid fat crystals and water droplets embedded in a continuous mass of semi- solid 'free' fat that coats them all. The energy required for mixing together large quantities of fat and flour generates excessive heat, which causes the structure of the fat to break down and the water to separate out resulting in emulsification.

Controlling or influencing the temperature of the mixture during mixing therefore prevents the breakdown of the fat structure, thereby reducing or preventing emulsification of the mixture. Preferably, the step of manipulating the temperature of the mixture comprises reducing heat generation during mixing, and more preferably the temperature of the mixture is maintained below a threshold.

Industrial scale, mass manufacture and high-volume processing are terms intended to denote a scale sufficiently large that emulsification of the mixture is or would

otherwise be caused. The terms high-volume and large scale refer to the amount of mixture being processed at once, these amounts being high or large relative to the amounts used in a single home kitchen rubbing-in process.

In one embodiment, the industrial scale production uses a three-phase power supply, as opposed to a lower power supply (such as a single-phase supply) that could be used on a smaller scale.

hi one embodiment, the step of manipulating the temperature of the mixture comprises controlling the timing of the mixing implements.

The inventor has recognised that the use of timing control in mixing fat and flour greatly reduces the build up of heat in the mixture, thereby reducing or preventing emulsification of the mixture.

Preferably, the mixing implements are operated at low speed, such as 1500rpm or less, or the mixing implements operate during a fixed period, or in timed bursts, such as bursts of 5 seconds with 5 second breaks, or at variable speeds. This prevents the shattering of the surface tension of the fat as occurs when energy pours into the fat during continuous high speed blending, and also allows any heat built up to disperse to a sufficient extent during any breaks to ensure heat levels do not get high enough to cause emulsification.

hi one embodiment, the step of manipulating the temperature of the mixture comprises mixing the mixture with a cutting action, rather than a stirring or paddling action, thereby reducing the shearing force applied to the fat.

The inventor has recognised that the use of a cutting action in this manner in mixing fat and flour greatly reduces the build up of heat in the mixture, thereby reducing or preventing emulsification of the mixture.

Preferably, one or more thin cutting elements, such as thin blades or wires or discs, are used as the mixing implements. Suitably, a plurality of mixing implements are evenly spaced on a support shaft. The use of such thin elements helps to keep temperatures down unlike paddles which have a greater surface area and therefore a higher likelihood of producing and retaining heat. Such thin elements also lessen the breaking down of fat globules, embedded in the continuous mass of semi-solid "free" fat which coats them, into smaller droplets, and prevents the water held in the fat separating out, both of which would otherwise lead to emulsification.

In one embodiment, the step of manipulating the temperature of the mixture comprises chilling the fat before mixing, preferably to between 2 and 8 degrees Celsius. This reduces the heat generated during mixing, and the energy required to mix the fat in.

Preferably, fat which has been cut into portions is used, or the fat is cut into portions before mixing, for example portions of 25Og or less. This is because large blocks take more energy to be mixed, creating more heat which warms and softens the fat, making it unstable. Suitably, further ingredients are added only after the fat and flour have been mixed.

In general terms, other aspects of the invention comprise producing a rubbed fat and flour mixture on an industrial scale, using the steps of: adding flour to a mixing container; adding fat to the mixing container; mixing the fat and flour using one or more motorised mixing implements; and sealing the container during mixing, thereby reducing or preventing intake of air into the mixture and retarding activation of gluten in the flour.

The inventor has recognised that if the flour contains gluten, the action of oxygen from the air drawn in to the bowl during mixing causes gluten molecules in the flour to bond end to end and form long viscous chains, resulting in the mixture clogging.

Preferably, the means for manipulating the temperature of the mixture comprises a material having a heat conductive property from which any of: the container; the

mixing implements; and the lid are fabricated. The heat conductive property may be high, low or zero heat conduction. This helps to prevent heat build up or disperse any heat to other areas of the apparatus. Suitably, the material is adapted to be chilled, preferably by means enabling chilled water to circulate around it.

Suitably, the fat content of the mixture as a ratio of fat to flour is at least 1 :4 (25%), preferably greater than 3:10 (30%), and more preferably 42%, by weight or by volume.

The above aspects and embodiments may be combined to provide further aspects and embodiments of the invention.

The invention will now be described by way of example with reference to the accompanying drawings, in which:

Figure 1 is diagram illustrating an example mixer configuration for a vertical mixer according to an embodiment of the invention;

Figure 2 is diagram illustrating the stages, optimum mixing speeds and timings for the processing of the raw crumb baking mix, according to an embodiment of the invention;

Figures 3a, 3b and 3c are diagrams illustrating the mixer blade attachment of Figure 2;

Figure 4 is diagram illustrating the spacing of the blades on the blade shaft according to an embodiment of the invention; and

Figures 5 a and 5b are diagrams illustrating alternatives for the configuration of the blades, according to embodiments of the invention.

Figure 1 illustrates a mixer configuration for a vertical mixer according to an embodiment of the invention. The timing controls 1, 2 and 3 serve individually or in combination to reduce the heat which would otherwise build up in mixing the fat and flour, for example by slowing the process, or providing breaks to allow any excess heat to disperse. This helps to reduce or prevent ernulsification.

The Mixer Timer Control 1 operates the mixer in short timed bursts, such as 5 seconds with 5 second breaks, so that heat build-up disperses in the rests between bursts of mixing, helping to reduce or prevent emulsification. The mixture is hence broken down more slowly.

Mixer Speed Control 2 operates the mixing at low speeds, such as 1500rpm or less, so that the surface tension of the fat is not shattered in the same way as occurs when energy pours into the fat during continuous high speed blending.

Mixer Pulse Control 3 is optionally provided, and may operate the mixing with an automatic mix-rest operation, to ensure heat levels do not get high enough to cause emulsification.

Reverse mixing action control 4 is optionally provided, and operates a reverse function implemented after the fat and flour have been mixed. Additional ingredients, such as dried fruit may hence be folded in without being cut up.

Mixing bowl lid 5 is made of material that has a heat conductive property, for example a low heat conductive material such as stainless steel to reduce the heat build up during mixing. The material may also be highly heat conductive, to allow transfer of heat away from the mixture, or of extremely low heat conductivity, to localise any heat generated.

The lid may provide a seal for the mixing bowl, in order to prevent air being drawn in during mixing, thereby retarding activation of gluten in the flour by oxygen.

Mixing bowl 6 is made of the material that has a heat conductive property.

The material with the heat conductive property which makes up certain components is, in another embodiment, adapted to be chilled, for example by an enclosing jacket enabling chilled water to circulate around it.

Mixing blades 7 are thin cutting blades or wires or discs, rather than paddles, which are also made of the material having a heat conductive property. Thin blades or wires or discs have a much lower surface area, which creates less heat and less shearing force dragging on the fat, meaning that the fat globules embedded in the continuous mass of semi-solid 'free' fat that coats are not broken down into smaller droplets and the water held in the fat does not separate out, which results in the prevention of emulsification of the mixture

The mixing blades 7 are attached to mixing blade shaft 8. These may be evenly spaced along the shaft.

In an alternative embodiment, the key elements of the mixer of Figure 1 are applied in configuration of a trough mixer.

The mixer may incorporate a cooling section for chilling the fat before mixing. The mixer may also incorporate a pre-cutting section, for chopping the fat into portions before mixing.

Figure 2 is a flow diagram defining the stages, optimum mixing speeds and timings for the processing of the raw crumb baking mix according to embodiments of the invention.

In an embodiment, the fat is cut up into portions before mixing, for example into portions of 25Og or less. In another embodiment butter or fat already broken down into small pieces nibs, pellets or granules is used. These take less energy to mix in.

The flour is added to the bowl first and then the fat is added. The fat may be chilled, for example to between 2 and 8 degrees Celsius. The bowl lid is closed to seal the mixture in the container and reduce or prevent intake of air. The timer is set for 5 second periods, and the mixing action is started at 1500rpm for 5 seconds. Mixing is then paused, for example for 5 seconds. This mix and rest cycle is then repeated, up to a total mixing time of 40 seconds. The mixer lid is then opened, and any additional ingredients can be added in an optional reverse operation function. A blunt edge opposite the cutting edge on each blade allows additional ingredients, such as dried fruit to be folded in without being cut up. Other ingredients, such as sugar, baking powder, dried fruit and chocolate chips may be added at this stage.

After mixing, the mixture may be put through a sieve to ensure uniformity of crumb size.

The mixer of this embodiment is run from a three-phase power supply, as commonly used in mass manufacture. The mixer may of course be adapted to be run from other power supplies.

The mixture typically has a fat content as a ratio of fat to flour, by weight or volume, of at least 1:4 (25%), and may be greater than 3:10 (30%), and in a particular embodiment is 42%.

Figures 3 a, 3b and 3 c show that the mixer blade attachment may include single or multiple blades. These blades may be evenly spaced around the blade shaft. The same principle applies for wire cutters.

Figuxe 4 shows that where multiple blades are used they may be evenly spaced along the blade shaft for optimum performance.

Figures 5a and 5b shows that the front edge 9 of the blades may be the cutting edge, but the back edge 10 of the blade is flat, similar to a paddle, to enable slow reverse mixing in of other ingredients without cutting them up.

The device may include a heat sensor for checking the temperature of the mixture. The output of the sensor may be used to control any of the described components of the device in order to lower the temperature. The sensor may set a threshold below which the temperature of the mixture is to be kept.

Although the use of flour has been described herein with reference to embodiments of the invention, this should not be interpreted as being limited to the use of wheat flour. Indeed, any variety of flour, such as potato, Soya or rice flour, may be employed in embodiments of the invention, and indeed any variety of finely ground or powdered foodstuff.

As the above described methods and devices involve no additional processing such as part baking or crushing of ingredients, and no adaptation of ingredients such as the dehydration of fats, the end product can use the types of ingredients consumers would choose themselves if baking from scratch, and fully retains the flavour and texture of the original ingredients, making it indistinguishable from what the consumer might make by hand in their own kitchen.

The various methods and devices described herein which reduce or prevent emulsification and clogging in mass production of a rubbed fat and flour mixture may, of course, be implemented individually to those effects. These methods and devices may also be combined in order that their reducing or preventative effects may be combined, thereby more effectively countering emulsification and clogging. For example, very high

fat content mixtures might only be achieved by employing two or more of the methods and devices described in combination.

It will be appreciated by those skilled in the art that the invention has been described by way of example only, and that a variety of alternative approaches may be adopted without departing from the scope of the invention, as defined by the appended claims.