GB1580442A - Production of biscuits - Google Patents

Description

(54) IMPROVEMENTS RELATING TO THE PRODUCTION OF BISCUITS (71) We, BAKER PERKINS HOLDINGS LIMITED, a British Company, of Westfield Road, Peterborough, PE3 6TA, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: During or shortly after the cooling of biscuits subsequent to leaving the oven in which they are baked, there is a tendency for cracks to appear in the biscuits which will cause them to break during subsequent handling. This is most undesirable, particularly when such breakage takes place after the biscuits are enclosed in their package wrapping so that upon opening of the package the consumer finds the contents broken.

Tests have shown that the cracking, or as it is called in the trade "checking", is induced by shrinkage of the centre of the biscuit as moisture remaining in the biscuit after baking migrates to the dryer areas at the edges of the biscuit.

Two of the main factors which can influence the incidence of checking are the biscuit ingredient specification, i.e. the recipe for the dough and the mixing and biscuit forming process. For any particular type of biscuit these two factors are largely predetermined and little, if anything, can be done in this respect to reduce the incidence of checking.

In situations where a biscuit recipe and production conditions combine to produce a biscuit which is prone to checking, we have now found that cooling is a very critical factor and according to the present invention this is controlled by conveying the biscuits from the oven through a region of circulating air at predetermined temperature and humidity.

The common and traditional method of cooling biscuits after they leave the baking oven is to expose them to ambient conditions for relatively long periods, usually on band conveyors which are run over head in order to save space. This results in gentle cooling but requires long conveyor runs, often twice the length of the oven, which can be of the order of from four hundred to six hundred feet. The resultant slow cooling action is usually fairly satisfactory in holding down the incidence of biscuit checking, but it is generally necessary for the biscuits to be lying flat on the conveyors which is a main reason for the amount of space required.

If, in an attempt to reduce the length of cooling conveyor the biscuits are cooled in stacked form, this is found to lead to an unacceptable degree of checking and even when lying flat, the variation of ambient air conditions with climatic changes can lead to unacceptable results. These disadvantages are overcome by means of controlled cooling in accordance with the invention which not only speeds up the process of cooling, but makes it possible to carry out the cooling with the biscuits in stacked form, i.e. resting on their edges. As a consequence, the total area of cooling conveyor is greatly reduced while at the same time ensuring an acceptably low level of checking.

Whereas it is not uncommon to employ controlled cooling in the bread industry so as to cool loaves under conditions which prevent hardening, breaking and cracking of the crusts, such controlled cooling has never previously been used in the production of biscuits. With bread, the moisture content after baking is commonly about 37% and the main purpose of the control during cooling is to prevent an excessive moisture loss which adversely affects the crust. In biscuits, by contrast, the moisture content is commonly only about 3% so that there is no problem of moisture loss and thus no appear ent need for controlled conditions of humidity during cooling. It is a surprising outcome of a process in accordance with the present invention that the controlled con-.

ditions during cooling tend to stabilise the distribution of moisture throughout the biscuit so that a state of equilibrium can be established without causing excess strain leading to checking.

The conditions to be applied during cooling may vary quite widely, depending on the type of biscuits, the type of conveyor on which they are supported and also on whether the biscuits are lying flat or are in stacked form. Generally speaking, at least a proportion of the cooling air needs to be cooled below ambient temperature. Under some circumstances all the air may be cooled and under other circumstances the air may be at ambient temperature in some part or parts of the travel of the conveyor and refrigerated at another part or parts. Thus ambient air can be used where the biscuits are hottest when leaving the oven and refrigerated air with forced circulation used when the initial heat has been removed from the biscuits. Whatever the temperature of the air, the biscuits are most conveniently conveyed on a conveyor band of open-work construction through which the cooling air is blown. For this purpose the air may be supplied through a plenum chamber from a fan and, after passing through the conveyor may then travel in a closed circuit back to the fan.

An example of apparatus suitable for use in a method in accordance with the invention will now be described with reference to the accompanying drawing which is a diagrammatic elevation.

The biscuits to be cooled pass from the oven in which they have been baked on a conveyor band 2, preferably in a stacked configuration. The conveyor band 2 is of open-work construction so as to allow the passage through it of cooling air. As seen in the drawing, the conveyor band 2 travels to the right through a closed chamber 3, the return run shown as 4 travelling in a space beneath the chamber 3, which is supported by legs 5. As made clear by the vertical divisions, the chamber is of unit construction so that it can be assembled to any required length. The upper part 7 of the chamber constitutes a plenum chamber supplied with air under pressure from a fan 8.

The air passes downwardly from the plenum chamber 7 through a row of outlet nozzles 10, as indicated by the vertical arrows. It then passes over the surface of biscuits supported on the conveyor band 2, through the conveyor and into a lower space 11. The air then flows horizontally along the space 11 to the centre of the assembly from where it passes upwardly through ducting on either side of the chamber 3, in the region shown as 12. It then flows through a filter 13 fitted with a manometer 14 to detect any loss of pressure across the filter and hence incipient clogging and thence passes back to the fan 8 to complete a closed circuit.

The fan 8 is enclosed within an insulated enclosure 15 formed in two parts mounted above corresponding units making up part of the main chamber 3. The fan is driven by a motor 16 and flow through the fan in controlled by a damper arrangement 17.

The air drawn into the fan is humidified by a steam injector 18 which is controlled by a hygrometer 20 which measures the humidity of the air after it has passed through the fan 8. This air also passes over cooling coils shown diagrammatically as 21 which are thermostatically controlled so as to maintain the air at any desired temperature.

Consequently, the air supplied by the fan 8 to the plenum chamber 7 is at a controlled temperature and humidity thus tending to stabilise the distribution of moisture throughout the biscuits supported on the conveyor band 2, thus reducing checking of the biscuits to a very low level.

As explained previously, the conditions under which biscuits are cooled depend on a number of factors including particularly the type of biscuits involved and the apparatus just described is capable of adjustment to suit any particular set of requirements. A factor which is common to all the different types is the need to cool the biscuits from something about 100"C, the temperature after baking, down to a temperature below 50"C, at which they can be wrapped. With the traditional gentle cooling described earlier, a large volume of ambient, still air is heated and the relative humidity is low in relation to air outside the bakery, e.g. about 35%. Forced circulation of air within an enclosed system leads to an even greater rise in the temperature of the air passing over the biscuits and without humidity control this would have the effect of lowering the relative humidity even more.

As a result of controlled humidification by means of a steam or water spray, the relative humidity may be kept in a range between 75% to 80% which is found to be ideal for the purposes of the present invention the cooling air being kept generally within a range of 40"C to 450C. Not only is the checking very materially reduced, but there is also an appreciable economy of space in the bakery.

WHAT WE CLAIM IS: 1. A method of producing biscuits with a low level of checking including the step of conveying the biscuits from an oven and through a region of circulating air at predetermined temperature and humidity whereby to obtain controlled cooling of the biscuits.

2. A method according to claim 1, in which the biscuits are conveyed in a stacked configuration.

3. A method according to claim 1 or

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. biscuit so that a state of equilibrium can be established without causing excess strain leading to checking. The conditions to be applied during cooling may vary quite widely, depending on the type of biscuits, the type of conveyor on which they are supported and also on whether the biscuits are lying flat or are in stacked form. Generally speaking, at least a proportion of the cooling air needs to be cooled below ambient temperature. Under some circumstances all the air may be cooled and under other circumstances the air may be at ambient temperature in some part or parts of the travel of the conveyor and refrigerated at another part or parts. Thus ambient air can be used where the biscuits are hottest when leaving the oven and refrigerated air with forced circulation used when the initial heat has been removed from the biscuits. Whatever the temperature of the air, the biscuits are most conveniently conveyed on a conveyor band of open-work construction through which the cooling air is blown. For this purpose the air may be supplied through a plenum chamber from a fan and, after passing through the conveyor may then travel in a closed circuit back to the fan. An example of apparatus suitable for use in a method in accordance with the invention will now be described with reference to the accompanying drawing which is a diagrammatic elevation. The biscuits to be cooled pass from the oven in which they have been baked on a conveyor band 2, preferably in a stacked configuration. The conveyor band 2 is of open-work construction so as to allow the passage through it of cooling air. As seen in the drawing, the conveyor band 2 travels to the right through a closed chamber 3, the return run shown as 4 travelling in a space beneath the chamber 3, which is supported by legs 5. As made clear by the vertical divisions, the chamber is of unit construction so that it can be assembled to any required length. The upper part 7 of the chamber constitutes a plenum chamber supplied with air under pressure from a fan 8. The air passes downwardly from the plenum chamber 7 through a row of outlet nozzles 10, as indicated by the vertical arrows. It then passes over the surface of biscuits supported on the conveyor band 2, through the conveyor and into a lower space 11. The air then flows horizontally along the space 11 to the centre of the assembly from where it passes upwardly through ducting on either side of the chamber 3, in the region shown as 12. It then flows through a filter 13 fitted with a manometer 14 to detect any loss of pressure across the filter and hence incipient clogging and thence passes back to the fan 8 to complete a closed circuit. The fan 8 is enclosed within an insulated enclosure 15 formed in two parts mounted above corresponding units making up part of the main chamber 3. The fan is driven by a motor 16 and flow through the fan in controlled by a damper arrangement 17. The air drawn into the fan is humidified by a steam injector 18 which is controlled by a hygrometer 20 which measures the humidity of the air after it has passed through the fan 8. This air also passes over cooling coils shown diagrammatically as 21 which are thermostatically controlled so as to maintain the air at any desired temperature. Consequently, the air supplied by the fan 8 to the plenum chamber 7 is at a controlled temperature and humidity thus tending to stabilise the distribution of moisture throughout the biscuits supported on the conveyor band 2, thus reducing checking of the biscuits to a very low level. As explained previously, the conditions under which biscuits are cooled depend on a number of factors including particularly the type of biscuits involved and the apparatus just described is capable of adjustment to suit any particular set of requirements. A factor which is common to all the different types is the need to cool the biscuits from something about 100"C, the temperature after baking, down to a temperature below 50"C, at which they can be wrapped. With the traditional gentle cooling described earlier, a large volume of ambient, still air is heated and the relative humidity is low in relation to air outside the bakery, e.g. about 35%. Forced circulation of air within an enclosed system leads to an even greater rise in the temperature of the air passing over the biscuits and without humidity control this would have the effect of lowering the relative humidity even more. As a result of controlled humidification by means of a steam or water spray, the relative humidity may be kept in a range between 75% to 80% which is found to be ideal for the purposes of the present invention the cooling air being kept generally within a range of 40"C to 450C. Not only is the checking very materially reduced, but there is also an appreciable economy of space in the bakery. WHAT WE CLAIM IS:

1. A method of producing biscuits with a low level of checking including the step of conveying the biscuits from an oven and through a region of circulating air at predetermined temperature and humidity whereby to obtain controlled cooling of the biscuits.

2. A method according to claim 1, in which the biscuits are conveyed in a stacked configuration.

3. A method according to claim 1 or

claim 2 in which at least a proportion of the air is cooled below ambient temperature.

4. A method according to any one of the preceding claims in which the biscuits are conveyed on a conveyor band of openwork construction through which the cooling air is blown.

5. A method according to claim 4 in which the air is supplied to a plenum chamber from a fan and, after passing through the conveyor, travels in a closed circuit back to the fan.

6. A method according to any one of the preceding claims in which the air is humidified by steam or an atomized water spray blown through a nozzle.