Frozen pizzas are a popular consumer food product which may be conveniently stored in a home freezer until consumption is required. Typically, the pizza is then removed from the freezer and cooked directly (reheated) from frozen in an oven. This avoids an inconvenient delay for defrosting. However, because of the low temperature of the pizza when it is removed from the freezer, a relatively long cooking time is required compared to a fresh pizza in order to bring the centre of pizza up to the necessary temperature for palatability and bacteriological safety. This effect is exacerbated with heavily topped deep pan pizzas. The disadvantage of this is that the outside of the pizza tends to dry out or burn, leaving a texture that is inferior to that of a fresh or chilled product.

Frozen pizzas are typically prepared by a method based on the following steps. A dough ball is first formed and then divided into individual balls of an appropriate size. A rounder is often used to form a neat ball. A dough ball of 200 to 250 grams might typically be used for a deep pan pizza of 9"diameter. The dough ball is then dropped onto a pan or tray having depressions designed to contain each individual pizza base. Oil is sprayed onto the tray and the dough ball as a release agent. The dough balls are then allowed to relax, typically for 10-15 minutes at 25-40°C, during which time the tension in the elastic gluten protein caused by dividing and rounding is allowed to subside. Some proving takes place due to the growth of yeast in the dough. Relaxation may take place at the room temperature of the bakery, but is liable to take longer for an equivalent result and may be less controlled. Relaxation may alternatively be carried out in a pocket prover before placement on a baking tray. In some circumstances the dough balls may be relaxed without proving (i. e. at room temperature).

Following relaxation, typically the dough ball is pressed on the tray to form a flat disc in a mechanical press. Usually, the pressing step is followed by another proving step and a further pressing step and a final proof to achieve the required diameter and depth, before baking at 180 to 280°C for around 5 minutes. The pizza base can then be removed from the pan or tray, cooled, and a topping may then be added before the product is frozen and packaged for distribution.

Although frozen pizzas made according to a method similar to that described above make up a large proportion of the market for packaged pizzas, the quality of the product differs in a number of ways from freshly prepared pizzas such as those served in high street restaurant chains. In particular, the restaurant pizza base is typically more moist and softer than the frozen product following reheating. This is not only because of the extended cooking time required for the frozen product, but also because the frozen product is normally baked twice, once before and once by the consumer after freezing.

Furthermore, the tray used to bake the product before it is frozen is only lightly oiled to assist in the release of the baked pizza from the tray or pan. Certain major restaurant products are baked in a tray containing much more oil, which results in a better flavour and a golden, crispy base. Furthermore, certain restaurant pizzas have a raised edge which is produced by applying toppings to the unbaked dough which suppresses the rising of the central portion of the dough disc.

Some products have an unbaked base in an attempt to emulate restaurant pizzas.

However, such products are not especially satisfactory since they have a less crisp base.

This results from the base being both frozen and uncooked when placed in a domestic oven.

For a number of years, manufacturers of frozen pizzas have sought to replicate the above properties of such major restaurant pizzas in a frozen product, but with limited success.

The present invention therefore aims to overcome many of the main disadvantages of the prior art methods for frozen pizza production, and in particular to provide an improved method for producing a frozen pizza, wherein following reheating the pizza has properties which are more similar to those of freshly prepared restaurant pizzas.

The present invention therefore provides a process for producing a frozen pizza base, comprising forming a dough disc to at least 50% of the final surface area of the pizza, adding the dough disc to a pan allowing the dough disc to prove or relax in the pan, baking the dough disc in the pan to form the pizza base and freezing the baked pizza base.

In a further aspect, the present invention provides use of a pan having a radiused edge in a method for preparing a frozen pizza base, wherein the pan is used to form a raised edge in the pizza base.

In a further aspect, the present invention provides a frozen pizza base or a frozen pizza obtainable by a method as defined above.

The present invention advantageously allows the production of a frozen pizza base which following reheating is more similar in quality to a freshly-prepared restaurant pizza than typical frozen pizzas. In the present method, a dough disc is formed before addition to the pan, in contrast to the prior art methods in which a rounded dough ball or'puck', which has been only lightly compressed (to fix its position), is added to the pan. Thus according to the present invention, the characteristic morphology of a pizza base is assumed before the dough is placed in its baking vessel. A number of advantages flow from the formation of a dough disc prior to addition to the pan.

Firstly, the present invention avoids the need to press the dough in the pan. Because in the prior art methods the pizza is pressed into a disc shape after addition of a dough ball to the pan, the pan can only be relatively lightly oiled. The addition of too much oil would lead to its expression from the depressions in the pan. The result of the low amount of oil used in the prior art methods is that the flavour and texture of the pizza base is diminished in comparison to certain restaurant products, which are cooked in a larger volume of oil.

In contrast, according to the present invention a larger volume of oil can be added to the pan prior to baking. This allows the underside of the dough to develop a crisp, lightly fried or golden patterned base similar to that of a pan-baked restaurant product. The greater degree of oiling also prevents the base tasting dry following reheating, adds to its flavour and its appeal to consumers.

Secondly, because the dough does not need to be pressed in the pan, the proving step of the present invention is more effective. Pressing typically exerts very high pressures (often around 600 psi) on the dough, which means that a significant proportion of the proving time is required for elastic recovery. According to the present invention, the dough disc is already relatively relaxed at the start of the proving step, and thus is capable of increased expansion. Moreover, in certain embodiments the proving step may be carried out in a single stage, in contrast to the prior art methods where a proving step is typically required after each pressing, and the duration of the proving step may optionally be extended. Thus the enhanced proof of the method of the present invention contributes to producing a pizza base having a lighter, fluffier, crumb texture than that of the prior art products. Not only is this in itself more appealing to consumers than the heavy texture of typical frozen pizzas, but it also reduces the cooking time required. This means that the base tends to burn and dry out less during reheating and also makes the product more appealing as a convenience food.

The enhanced proof also provides a further advantage which may be applied in certain embodiments to controlling the profile of the pizza. Because of the increased expansion of the dough in the present method, a radiused pan can be used to form a raised edge to the pizza base.

The present method involves forming a dough disc to at least 50% of the final surface area of the pizza. It is advantageous that the dough disc is formed prior to addition to the pan, in order that a pressing step is not required. The dough is typically formed by mixing flour, water, yeast, salt and optionally a fat or oil, and kneading using, typically, a high speed mixer or a slower spiral mixer. Dough relaxants such as L-cysteine hydrochloride or deactivated yeast may optionally be included. In certain embodiments, dough strengtheners such as diacetyltartaric esters of mono-and diglycerides of fatty acids (DATEM) or sodium steroyl-2-lactylate (SSL) are added. Both DATEM and SSL are dough conditioners due to their emulsifying properties and are obtainable from suppliers of food grade emulsifiers such as Danisco Ingredients, Arkady Craigmillar and Puratos.

The ingredients of the dough may be varied in order to vary the texture of the product as required. In particular, the water: flour ratio may be varied in order to adjust the texture of the base. From the above it will be clear that this may affect other attributes, such as the cooking time of the frozen product.

Preferably a weaker flour is used as this results in a light shorter texture and reheats more quickly. The flour used has typically a total protein content of about from 8-14% by weight. Preferably the protein content is from 9.5 to 11.5%. Where no gluten is added to the flour, the flour most preferably has a total protein content of 10.1 to 10.7%. In some embodiments the protein content of the flour is boosted by adding gluten whilst in other embodiments no gluten needs to be added.

Up to 1.25% by weight of the flour can be made up of added gluten, such as vital wheat gluten. Added gluten is typically less effective than natural flour protein at producing the required properties of the base. When the flour comprises added gluten, the protein content is preferably measured as an effective protein content rather than a total protein content. Nevertheless, the preferred effective protein content of the flour is within the ranges referred to above.

The effective protein content is given by the content of non-added gluten protein, plus the added gluten content multiplied by a factor taking into account the effectiveness of the gluten. This factor is dependent upon the effectiveness of the particular gluten that is added and is a number between zero and one. Typically the factor has a value of from 0.3-0. 5 and preferably a value of about 0.4. The effective protein content can be calculated using the following formula: Ps=Pnat + EPglu Where Pg is the effective protein content, Pnat is the natural protein content, Pglu is the added gluten content and s is the factor taking into account the effectiveness of the added gluten.

The initial and final protein content of the flour may suitably be adjusted to achieve the required strength, taking into account the reduced effectiveness of the added gluten. Thus where the flour comprises 1% added gluten, the added gluten will only be as effective as 0.4% of natural wheat protein. In order to achieve an effective protein content within the most preferred range of 10.1 to 10.7%, the initial protein content of the flour before addition of gluten would suitably be 9.7 to 10.3%, and the final protein content following addition of gluten would be 10.7 to 11.3%. Where the flour comprises 0.5% added gluten, the initial protein content would suitably be 9.9 to 10.5% and the final protein content would be 10.4 to 11%.

The method of forming the dough disc is not particularly limited. In a preferred embodiment, a rounded dough ball is first formed in a mechanical rounder. The dough ball is then relaxed or preferably proved, for instance in a pocket prover. The rounded dough ball is preferably deposited onto a surface and pinned out. Pinning involves the use of mechanical reduction rolls to flatten the dough balls to a substantially planar morphology.

It is preferable to pin out the dough ball in two steps. In this embodiment, the direction of rolling in the horizontal plane in the second pinning step is substantially orthogonal to the direction of rolling in the first pinning step, in order to achieve an approximately circular dough disc of the correct diameter for further processing.

Alternatively, the dough disc may be made by cutting discs of dough from a sheet formed by a continuous sheeting plant, preferably of the so-called low stress type.

The dough disc is typically cut or shaped to form the substantially planar, circular shape characteristic of pizzas. However, the term"disc"is intended to encompass pizza base shapes other than the traditional circular shape, such as square or irregularly shaped bases.

The dough disc is formed to at least 50% of the final surface area of the pizza base, which is the surface area determined after the baking step. Preferably the dough disc is formed to at least 70% of the final surface area, more preferably at least 90% of the final surface area and most preferably at least 95% of the final surface area. The dough disc may be formed to substantially 100% of the final surface area in certain embodiments. For a pizza product for consumption by say 1 to 4 people, the final surface area of the top of the disc is typically 180 to 800 cm2 for pizzas from about 15cm (6") through to about 30cm (12") in diameter and therefore the dough disc is formed to a surface area of 90 to 800 cm2. For a pizza base of final surface area of 400 cm2, the dough disc is formed to a surface area of 200 to 400 cm2, whereas for a pizza base of final surface area of 800 cm2, the dough disc is formed to a surface area of 400 to 800 cm2.

Typically a pizza base of diameter 12. 5cm (5") is suitable for preparing a pizza for consumption by a child as a main meal or an adult as a snack. A diameter of 15 to 18cm (6"to 7") is typically chosen for a main meal for a single adult, whereas 23cm (9") is suitable for two people. A diameter of 30cm (12") is appropriate for four or more people.

The thickness of the dough disc is not particularly limited. However if the disc is too thick, the product will not be well suited to freezing and reheating, as the cooking time will be too long leading to a burnt exterior and may lose the restaurant-style quality. The dough disc is typically 5 to 30 mm in thickness. The thickness of the dough disc may be controlled by the extent of the pinning or sheeting process and the quantity of dough in the ball.

Once the dough disc has been formed, it is transferred to a pan. The dough disc may be transferred to the pan by any suitable method, preferably by the use of a retracting conveyor apparatus. In this embodiment, the dough disc is formed on a surface which may be positioned substantially vertically above the pan. The surface is then retracted allowing the dough disc to drop onto the pan. Alternatively, the dough disc may be transferred by the use of a mechanised pick and place apparatus, or may be transferred using any suitable hand-held tool.

The pan may be any vessel suitable for baking the dough disc to form the pizza base. The pan may hold a single dough disc, or in a typical commercial production process a sheet may be employed having a number of depressions or indentations, wherein each depression or indentation is suitable for holding a single dough disc. In this embodiment, each depression or indentation is regarded as a pan. In a preferred embodiment, the surface area of each depression is substantially equal to the final surface area of the pizza.

Thus the surface area of each depression will typically be 0 to 100% greater than the surface area of the dough disc prior to proving. The dough disc is preferably deposited substantially into the centre of the depression such that during the proof, the dough expands towards the outer circumference of the depression. The profile of the depression is then capable of limiting and determining the shape of the pizza base, in particular the shape of the external circumference of the pizza.

Preferably the depression in the pan is 5 to 50 mm in depth, more preferably 14 to 40 mm in depth. The depth of the depression is preferably substantially constant over at least 95% of the surface area of the depression, so that the pizza base which is formed has an even lower surface.

The pan preferably has a radiused edge, as shown in a particular embodiment illustrated in Figure 1. The edge referred to is the curved portion of the pan between the base of the pan and the side wall of the pan. The edge radius is preferably 5 to 20 mm, more preferably 5 to 9 mm, and most preferably about 7mm. The radiused edge guides the dough as it expands during the proof. As the dough flows up the sides of the pan, this particular shape favours the formation of a raised edge to the pizza base. If the radius is too high the dough becomes too mobile and flows too far up the sides of the pan. Within the preferred range above, the flow of dough is sufficient to provide a raised edge without being too vigorous.

Preferably the raised edge comprises an annulus at the outer circumference of the pizza base of 5 to 50 mm width, wherein the upper surface of the pizza base between the inner and outer circumferences of the annulus is 2 to 20 mm above the upper surface of the pizza base within the inner circumference of the annulus.

In embodiments where a radiused edge is required, it is important that the rheological properties of the dough are compatible with the method and the starting size of the dough disc, such that the dough is capable of flowing up the sides of the pan to form the raised edge. This may be achieved through the inclusion of an appropriate level of water in the recipe in relation to the water absorption capability of the relatively weak flour, the proof time and temperature, the oil level in the pan as a lubricant and through the inclusion of suitable levels of dough relaxants and dough strengtheners as mentioned above.

The method preferably further comprises adding oil to the surface of the pan prior to the addition of the dough disc. The surface of the pan referred to here is the surface of the pan which comes into contact with the dough disc. Where the pan comprises a sheet having one or more depressions, the surface of the pan referred to is the base area of the pan or of the depression or indentation in the baking tray or baking sheet. The oil is preferably sprayed across the full surface area of the pan which comes into contact with the dough disc.

0.013 to 0.04 g of oil is preferably added per cm2 of the surface of the pan, more preferably 0.02 to 0.03 g per cm2. Typically 6 to 14 grams of oil would be added to a pan of surface area of around 410 cm2, or 10 to 25 grams to a pan of surface area of around 730 cm2. The oil may be any suitable animal or vegetable oil, typically soya, rapeseed (canola), corn or cottonseed oil, or any blend and/or emulsion of any such oil.

In a preferred embodiment, oil is also added to the rim of the dough disc. The dough disc may suitably be oiled prior to the addition of the dough disc to the pan, or alternatively after the addition of the dough disc to the pan. Oiling the dough disc helps to give a fried dough taste to the rim, protects the rim from drying out during baking and reheating and gives a smooth glossy appearance similar to that of a restaurant pizza.

After addition of the dough disc to the pan, the dough disc is allowed to prove or relax.

Proving involves allowing the dough disc to expand due to the anaerobic fermentation of the yeast in the dough. The proving step may typically be carried out at a temperature from ambient (15-20°C) to 45°C, preferably at a temperature which enhances the flow characteristics of the dough due to the direct effect of the temperature itself, the relaxation of the gluten structure and to the enhanced biochemical effects of fermentation by the yeast. More preferably the proving step is carried out at 30 to 40°C. Proving is generally required when the surface area of the dough disc before proving is substantially smaller than the final surface area of the pizza base.

Alternatively, in certain embodiments the dough disc is allowed to relax without proving.

Relaxing involves allowing the dough disc to expand due to the elastic properties of the dough, and may be assisted by the addition of dough relaxants. The relaxing step is typically carried out at room temperature (generally 15-25°C). A relaxing step may suitably be used instead of proving if the surface area of the dough disc before relaxing is similar to the final surface area of the pizza base, in particular when the surface area before relaxing is at least 95% of the final surface area. This type of process leads to a crisper base having a more cracker-like texture.

The relative humidity during the proving or relaxing step is suitably 70 to 100%, in order to minimise drying and"skinning"of the dough surface which can impede flow in the pan. Preferably the dough disc is proved in a single step. By a single step it is meant that that the proving process occurs in a single period with no substantial interruption.

However, in this embodiment the single step may take place in a single prover, or may take place in two or more provers, provided that the interval occurring as the dough discs emerge from one prover to enter the next prover is short enough such that it does not substantially interrupt the proving process.

The duration of the proving step may be determined according to the nature of the product required (in particular its lightness and cooking time) and the desired degree of expansion of the dough disc. The proving time is preferably within the range of 10 to 60 minutes, more preferably 20 to 40 minutes. The precise proving time required is dependent on the initial dough disc diameter and thickness, the proof temperature, the dough rheology, the quantity of oil added to the pan and the style of the final product required.

Following proving or relaxing, the dough disc is baked to form the pizza base. Baking is typically performed in an oven at 150 to 350°C, preferably from 180 to 250°C. The baking time in a forced convection oven is preferably 2 to 10 minutes or more preferably around 5 minutes.

The baked product may then be frozen and optionally packaged for sale as a pizza base.

Alternatively, after baking a topping may be added. Suitable toppings include typically a tomato-based sauce followed by cheese, pepperoni, salami, tomato, mushroom, pineapple, ham, bacon, spinach, egg, peppers, tuna, olives, sausage, or baked beans or any combination of the above. It is important that the topping is distributed evenly over the surface of the base. If the topping is unevenly distributed (for instance if it is deposited only into the centre of the base), the pizza may cook unevenly. Parts covered by too much topping may be undercooked while uncovered parts of the base may become overcooked.

The topping may be added before the freezing step, or alternatively the topping may be added after the base has been frozen. In the latter case, the pizza comprising the base and topping is preferably subsequently re-frozen following addition of the topping.

Example-Preferred type of baking tray.

Figure 1 shows a diagram of a suitable baking tray for use in the present invention. The tray is shown as viewed from above and in cross-section.

The overall dimensions of the tray (A) are 825 mm square. The tray has 9 depressions, each of which constitutes a pan for accommodating a single dough disc to form a pizza base. The distance between the centres of the pans is 247.5 mm (B). The diameter of each pan (C) is 228 mm measured across the upper edge of the tray, and 190 mm measured across the flat part of the base of the tray (D). The depth of each pan is 28 mm (E) and the radius of the corner of each pan is 17 mm (F). The tray also comprises a strengthening bar around the sides of the tray of height 14.5 mm (G).