Background to the Invention

The present invention relates to a method of manufacturing snack food chips, in particular tortilla chips.

Description of the Prior Art

The manufacture of snack food chips well known. A variety of different snack food chips is known having various shapes and configurations, and compositions.

It is known to provide tortilla chips, which are composed of a maize-based composition (maize hereinafter being called "corn" in accordance with the terminology used in the United States) which has been formed as a corn masa dough, which is sheeted, cut into individual dough pieces, which are typically triangular in plan (although other shapes are widely known), toasted in an oven and then fried. The fried chips are then seasoned. The masa dough uses fresh corn which has been subject to a nixtamalization process, in which the corn is boiled in an aqueous solution comprising lime, then allowed to soak in the solution and then the corn is washed and ground to produce corn masa.

US Patent Application Publication Nos. US 2005/0260314 A 1 and US 2008/0044534 Al , both in the name of Baker et al., disclose a method of making a masa-based dough to produce a fried tortilla chip-like product, in which starch is added to corn masa dough to help control moisture release during frying. The dough ingredients include dry corn masa which is combined with pre-hydration water and mixed to make a pre-hydrated masa, then starches and minor ingredients are mixed with the pre-hydrated masa to form a flour, and then water is added to the flour to make an aerated buoyant masa dough. In an example the added starches are potato starch (pre-gelatinized) and modified starch.

Consumers generally desire tortilla chips which have particular visual characteristics, in particular a chip without any holes extending through the thickness of the chip and a blistered surface which comprises a distribution of small blisters on the surfaces of the chip. The blisters give the tortilla chip a more natural hand-fried appearance as compared to a uniformly flat surface. However, the blisters should be uniformly distributed over the chip surface, have a regular size distribution and should not be excessively punctured. Also, the chips should not be cracked or have through-holes therein. In order to provide the blistered surface, the oven toasting step is used. This oven toasting step case-hardens the raw dough piece, i.e. creates a hard surface layer while leaving a raw dough composition in the middle of the chip. In the subsequent final cooking step, namely frying, the surface of the tortilla chip becomes uniformly blistered with an array of surface blisters. The surface blisters are bubble-like voids extending away from the body of the chip, and preferably have a continuous curved wall, which is substantially semi-spherical or semi-ovoid, above the body of the chip. Some blisters may have a punctured wall, but preferably a majority of the blisters, i. e. at least 50% by number, are unpunctured during the manufacturing process. These blisters are formed by steam which is generated by cooking the moisture-containing dough; the steam is formed in the flexible starch matrix and then expands to form the blisters. If the oven toasting step is omitted, a "pillow" would be formed from the dough piece, by separation and expansion of the opposed outer surfaces of the dough piece. However, when oven toasting is employed, the case hardened outer surfaces provide a plurality of localised weak points, which result in the formation of a plurality of blisters. Nevertheless, the known toasting process tends to cause uneven drying on the surface of the chip, which in turn tends to provide a moisture gradient which leads to uncontrolled blister sizes on the chip surfaces after frying.

There is currently no known tortilla chip manufacturing method to produce tortilla chips with a controlled level of blistering which does not employ a toasting oven to carry out a preliminary toasting step prior to final cooking or which does not use fresh corn to produce a masa dough, as described above, immediately upstream of the cooking apparatus so that the dough comprises fresh corn.

If a masa dough using fresh corn is employed using only a frying step as the cooking step, and does not employ a toasting step, typically the resultant fried chip has an expanded pillow-like structure, i.e. a large central void surrounded by the interconnected peripheral edges of two opposed layers of the tortilla chip, or the tortilla chip does not exhibit any significant blistering. The toasting step is added to form case-hardened surfaces which then are readily able to form blisters in the subsequent frying step. However, the use of fresh corn and a toasting oven both increase the cost and complexity of the tortilla chip manufacturing line.

It is known to make tortilla chips using corn masa flour and without the use of fresh corn processed upstream of the dough manufacture. However, that process suffers from the problem that an oven toasting step is required to case harden the chips to control blistering. In addition, the tortilla chips tend to have a low blister count and an undesired grainy texture. Summary of the Invention

There is a need in the art to provide a method of manufacturing snack food chips, in particular tortilla chips, that can provide a product of highly acceptable appearance and morphology to the consumer, in particular with a controlled level of blistering, and which can be produced in an efficient and cost-effective manner.

The present invention aims at least partially to meet those needs.

The present invention accordingly provides a method of manufacturing snack food chips, the method comprising the steps of: i. providing a first starch-containing component which comprises a cold water swelling starch, a second starch-containing component which comprises substantially ungelatinized starch, and a third starch-containing component which comprises corn masa flour;

ii. forming a dough from a mixture of the first, second and third starch-containing components and water, wherein the dough comprises from 35 to 75 wt% corn masa flour, from 10 to 40 wt% of the second starch-containing component, and from 5 to 30 wt% of the first starch-containing component, each based upon the weight of dry ingredients of the dough, and the dough comprises from 25 to 35 wt% added water, based on the weight of the dough, wherein the dough is formed at a temperature of up to 30 °C by mixing dry ingredients of the dough with water for a period of from 3 to 60 seconds and the cold water swelling starch forms a gel matrix in the dough;

iii. forming a dough sheet from the dough, wherein the dough sheet has a thickness of from 0.5 to 1.5 mm;

iv. cutting a plurality of dough pieces from the dough sheet; and

v. cooking the dough pieces to form a plurality of snack food chips.

In preferred embodiments of the present invention, in step i the first, second and third starch- containing components are each dry ingredients and optionally are formed as a dry mixture for forming the dough in step ii.

In preferred embodiments of the present invention, in step ii the mixing of dry ingredients of the dough with water is for a period of from 3 to less than 60 seconds. In preferred embodiments of the present invention, in step ii the dough is formed at a temperature of from 5 to 20 °C, further optionally from 10 to 15 °C.

In preferred embodiments of the present invention, the third starch-containing component further comprises at least one further corn ingredient, the further corn ingredient being selected from fresh corn masa, raw corn flour and cooked corn flour or any mixture of any two or more thereof.

In preferred embodiments of the present invention, the dough does not comprise a fresh corn masa ingredient.

In preferred embodiments of the present invention, the dough comprises from 45 to 70 wt optionally from 50 to 65 wt%, corn masa flour, based upon the weight of the dry ingredients of the dough.

In preferred embodiments of the present invention, the dough comprises from 15 to 30 wt% of the second starch-containing component, based upon the weight of the dry ingredients of the dough.

In preferred embodiments of the present invention, the dough comprises from 20 to 30 wt%, optionally about 25 wt%, of the second starch-containing component, based upon the weight of the dry ingredients of the dough.

In preferred embodiments of the present invention, the second starch-containing component is selected from tapioca starch and corn starch or a mixture thereof and optionally comprises tapioca cook-up starch and/or waxy corn cook-up starch.

In preferred embodiments of the present invention, the cold water swelling starch has a peak viscosity at a temperature of less than 50 °C, when measured by a rapid viscosity analyser (RVA) in excess water having a weight of water which is 3 times the weight of the cold water swelling starch.

In preferred embodiments of the present invention, cooking step v is carried out to cause the substantially ungelatinized starch in the second starch-containing component to gelatinize, the snack food chips comprising a starch matrix formed from the first and second starch-containing components, and corn masa particles dispersed in the starch matrix. In preferred embodiments of the present invention, in cooking step v the second starch- containing component gelatinizes to form a continuous flexible starch matrix in which entrapped steam forms bubbles which cause expansion of the continuous flexible starch matrix.

In preferred embodiments of the present invention, the second starch-containing component has a peak viscosity at a temperature of from 50 to 80 °C, optionally from 60 to 70 °C, when measured by a rapid viscosity analyser (RVA) in excess water having a weight of water which is 3 times the weight of the second starch-containing component.

In preferred embodiments of the present invention, the third starch-containing component has a peak viscosity at a temperature of greater than 80 °C, when measured by a rapid viscosity analyser (RVA) in excess water having a weight of water which is 3 times the weight of the third starch-containing component.

In preferred embodiments of the present invention, the dough comprises from 5 to 20 wt% of cold water swelling starch in the first starch-containing component, based upon the weight of the dry ingredients of the dough.

In preferred embodiments of the present invention, the dough comprises from 10 to 15 wt%, optionally about 12 wt%, of cold water swelling starch in the first starch-containing component, based upon the weight of the dry ingredients of the dough.

In preferred embodiments of the present invention, the first starch-containing component is selected from a pre-gelatinized cereal flour, a pre-gelatinized starch derivative, or any mixture thereof.

In preferred embodiments of the present invention, the first starch-containing component is at least one pre-gelatinized cereal flour selected from corn, wheat, barley, rice, spelt, or any other grain-derived product, or any mixture thereof.

In preferred embodiments of the present invention, the first starch-containing component is a pre-gelatinized corn flour.

In preferred embodiments of the present invention, the dough further comprises from 5 to 20 wt%, , based upon the weight of the dry ingredients of the dough, of at least one cereal flour selected from wheat, barley, rice, spelt, or any other grain-derived product, or any mixture thereof. In preferred embodiments of the present invention, the dough comprises from 10 to 15 wt%, based upon the weight of the dry ingredients of the dough, of at least one cereal flour selected from wheat, barley, rice, spelt, or any other grain-derived product, or any mixture thereof.

In preferred embodiments of the present invention, the cooking consists of frying and there is no oven or toasting step prior to the frying step.

In preferred embodiments of the present invention, the dough comprises from 25 to 30 wt added water, based on the weight of the dough.

In preferred embodiments of the present invention, the dough further comprises from 0.2 to 1.5 wt% of an emulsifier which is adapted to bind to free starch, based on the weight of the dough.

In preferred embodiments of the present invention, the emulsifier is a monoglyceride- diglyceride emulsifier comprising a mixture of at least one monoglyceride and at least one diglyceride, optionally the monoglyceride-diglyceride emulsifier comprising or consisting of a food additive having E-number E471.

In preferred embodiments of the present invention, the dough comprises from 0.2 to 0.5 wt% of the emulsifier, based on the weight of the dough.

In preferred embodiments of the present invention, the weight ratio of the added water: emulsifier in the dough is from 25: 1 to 200: 1.

In preferred embodiments of the present invention, the weight ratio of the added water: emulsifier in the dough is from 50: 1 to 150: 1 , optionally from 75: 1 to 125: 1.

In preferred embodiments of the present invention, the corn masa flour has a particle size falling at least partly within the range extending from a fine particle corn masa, in which at most 30 wt% of the fine particle corn masa is retained on a 500 μηι sieve and at least 25 wt% of the fine particle corn masa passes through a 250 μπι sieve, to a coarse particle corn masa, in which at least 6 wt% of the coarse particle corn masa is retained on an 850 μπι sieve and at most 35 wt% of the coarse particle corn masa passes through a 250 μηι sieve.

In preferred embodiments of the present invention, the corn masa flour is a mixture of two flours having respective particle sizes, optionally the mixture comprising from 20 to 45 wt%, typically from 30 to 40 wt%, of a first corn masa and from 55 to 80 wt%, typically from 60 to 70 wt%, of a second corn masa, each wt% being based on the weight of the corn masa flour, the first corn masa having a particle size range in which 0 wt% of the first corn masa is retained on a 2000 μπι sieve, at most 1 1 wt% of the first corn masa is retained on an 841 μηι sieve and at most 32 wt% of the first corn masa passes through a 149 μπι sieve, and the second corn masa having a particle size range in which 0 wt% of the second corn masa is retained on a 2000 μπι sieve, at most 22 wt% of the second corn masa is retained on an 841 μπι sieve and at most 26 wt% of the second corn masa passes through a 149 μπι sieve.

In preferred embodiments of the present invention, the dough sheet has a thickness of from 0.6 to 1 mm.

In preferred embodiments of the present invention, in step iii the dough sheet is formed in a sheeting apparatus at a linear speed for the sheet of from 20 to 60 linear metres/minute, optionally from 30 to 50 linear metres/minute.

In preferred embodiments of the present invention, the dough pieces are shaped against a mould during frying so that the snack food chips are three-dimensionally shaped with a preset shape.

In preferred embodiments of the present invention, the cooking comprises or consists of frying and the frying temperature is from 160 to 200 °C, optionally from 170 to 190 °C, further optionally about 180 °C.

In preferred embodiments of the present invention, the frying time is from 15 to 30 seconds, optionally from 16 to 25 seconds, further optionally from 18 to 23 seconds.

In preferred embodiments of the present invention, the dough is formed by mixing together the first, second and third starch-containing components to form a dry mix, and then mixing the dry mix with water and a monoglyceride-diglyceride emulsifier to form the dough, wherein the monoglyceride-diglyceride emulsifier comprises a mixture of at least one monoglyceride and at least one diglyceride, optionally the monoglyceride-digl yceride emulsifier comprising or consisting of a food additive having E-number E471.

In preferred embodiments of the present invention, the dry mix has a water content of from 5 to 20 wt% water, optionally from 10 to 12 wt% water, based on the weight of the dry mix.

In preferred embodiments of the present invention, when the dry mix is mixed with the water and monoglyceride-diglyceride emulsifier to form the dough the dry mix has a temperature of from 5 to 30 °C, optionally from 5 to 25 °C, and the water has a temperature of from 5 to 15 °C, optionally from 7 to 12 °C, further optionally from 8 to 1 1 °C. In preferred embodiments of the present invention, the dry mix is mixed with the water, and optional monoglyceride-diglyceride emulsifier, to form the dough for a period of from 3 to 30 seconds, optionally from 5 to 30 seconds.

In preferred embodiments of the present invention, the snack food chips comprise a starch matrix formed from the first and second starch-containing components, and corn masa particles dispersed in the starch matrix.

In preferred embodiments of the present invention, the snack food chip comprises a tortilla chip.

In preferred embodiments of the present invention, in a random population of 100 of the tortilla chips, more than 90% by number have a continuous wall without through-holes or cracks extending therethrough.

In preferred embodiments of the present invention, the cooking step is carried out to cause the snack food chip to have a plurality of blisters on opposite major surfaces each blister extending outwardly on both opposite major surfaces.

In preferred embodiments of the present invention, for a sample of 6 randomly selected chips, the blisters have a mean total number of blisters per cm ² of the opposite major surfaces of from 0.92 to 1.20, preferably from 1.00 to 1.20, with the blisters having a maximum width of 1.2 mm, optionally wherein for the sample of 6 randomly selected chips, the blisters include a mean total number of blisters having a maximum width of less than 0.5 mm of from 0.63 to 0.83, preferably from 0.68 to 0.78, blisters per cm ² , and a mean total number of blisters having a maximum width of from 0.5 to 1.2 mm of from 0.25 to 0.43, preferably from 0.30 to 0.38, blisters per cm ² .

The preferred embodiments of the present invention can provide a novel method of manufacturing a snack food chip, in particular a tortilla chip, which can exhibit a controlled level of blistering, in particular a uniform blister distribution over the chip surfaces, without employing a toasting or oven step prior to a frying step, the latter being the cooking step. Preferred embodiments of the present invention can provide that the controlled level of blistering is achieved without using fresh corn on the tortilla chip manufacturing line, i.e. without requiring a nixtamalization step carried out on fresh ground corn immediately prior to forming the dough. However, in some embodiments some fresh corn masa can be added to provide additional corn flavour and/or texture. The absence of an oven or toasting unit and the absence of a corn soaking unit in the tortilla chip manufacturing line reduces the capital costs and running costs of the manufacturing line. Also, the absence of a corn soaking unit simplifies the tortilla chip manufacturing process.

Furthermore, the dough of the preferred embodiments has been found to be cohesive and readily sheetable at high speed and the dough can be formed very quickly, even in a period as low as 3 seconds. The sheetable dough provides that after frying, without requiring a preliminary oven or toasting step, and using a prefabricated commercially available corn mas a flour, the tortilla chips do not exhibit any significant number of cracks or through-holes.

Without being bound by any theory, it is believed by the present inventors that the specific dough composition forms a continuous starch network from the initial cold water swelling starch, which has particles of corn masa distributed in the matrix. After cooking the tapioca starch expands and blisters are formed. Such a dough is cohesive and readily sheetable, and in turn permits the formation of a uniform and regular distribution of blisters during the frying process, and the absence of cracks or though-holes in the resultant tortilla chips.

The present invention is least partly predicated on the finding by the present inventors that by providing a dough comprising a first starch-containing component which includes cold water swelling starch (for example a pre-gelatinized flour), a second starch-containing component which comprises substantially ungelatinized starch (for example tapioca and/or corn starch, such as cook-up starch), and a third starch-containing component which comprises corn masa flour and other minor ingredients, some of which may be corn-based, the dough can be formed, readily sheeted, cut into pieces and then fried. No toasting step is required and the dough does not need to comprise fresh corn. A prefabricated dried corn masa flour can be employed to provide the entire corn masa component of the tortilla chip. No corn soaking steps are required in the dough and tortilla chip manufacturing lines.

The first starch-containing component includes cold water swelling starch which forms a gel matrix for the dough. The cold water swelling starch has a peak viscosity at a temperature of less than 50 °C, when measured by a rapid viscosity analyser (RVA) in excess water having a weight of water which is 3 times the weight of the cold water swelling starch. This can provide a cohesive sheetable dough that can be formed at a low temperature, for example at about room temperature or lower. The dough is formed at a temperature below the gelation temperature of both the second starch-containing component which comprises substantially ungelatinized starch (for example tapioca and/or corn starch, such as cook-up starch), and the third starch- containing component which comprises corn masa flour. The second starch-containing component has a peak viscosity at a temperature of from 50 to 80 °C, optionally from 60 to 70 °C, when measured by a rapid viscosity analyser (RVA) in excess water having a weight of water which is 3 times the weight of the second starch-containing component. The third starch- containing component has a peak viscosity at a temperature of greater than 80 °C, when measured by a rapid viscosity analyser (RVA) in excess water having a weight of water which is 3 times the weight of the third starch-containing component. When the dough is cooked, for example by frying, the dough is heated to a temperature above the gelatinization temperatures of the second starch-containing component and the peak RVA viscosity of the third starch- containing component.

Since the second starch-containing component has a peak RVA viscosity temperature below the peak RVA viscosity temperature of the corn masa, the second starch-containing component, for example tapioca and/or corn starch, rapidly absorbs water from the dough at the elevated cooking temperature, gelatinizes and expands due to the generation of steam. In the cooking step the second starch-containing component gelatinizes to form a continuous flexible starch matrix in which entrapped steam forms bubbles which cause expansion of the continuous flexible starch matrix. The water absorption of the second starch-containing component occurs preferentiallv to the water absorption of the corn masa of the third starch-containing component, which has a higher peak RVA viscosity temperature, and so the water in the dough is absorbed by the second starch-containing component, leaving the corn masa of the third starch-containing component as particles dispersed throughout the starch matrix and having little or substantially no water absorption in the corn masa.

Since the second starch-containing component is distributed homogeneously throughout the dough, the gelatinization occurs throughout the dough to form an expanded starch matrix together with the first starch-containing component. The expanded matrix forms a typical expanded and crunchy texture associated with tortilla chips. The substantially uniform gelatinization provides a plurality of nucleation sites for steam generation as the dough is rapidly dehydrated during cooking. The steam generated forms a substantially uniform array of a plurality of blisters, of substantially uniform size distribution, on opposite surfaces of the chip. Steam generation does not tend to occur at the corn masa particles, which may otherwise cause a non-uniform blister morphology and may cause local stresses in the matrix which could form through-holes or cracks in the cooked chip. The corn masa remains as particles which are substantially free of absorbed water and so does not form part of the starch matrix, but instead forms a substantially uniform distribution of particles in the matrix. The corn masa particles can provide a tortilla chip taste and crunch to the chip.

Accordingly, by providing three starch components having different peak RVA viscosity temperature characteristics, a sheetable dough can be formed at low temperature and a snack food chip with a corn taste and mouthfeel characteristics, exhibiting a substantially uniform surface blistering and substantially without through-holes or cracks, can be manufactured.

The preferred embodiments of the present invention can further provide a method for manufacturing three-dimensionally shaped snack food chips, such as tortilla chips, which exhibit the desired blistering. The shaped tortilla chips can be manufactured at low production costs as well as low capital expenditure. The dough pieces can be shaped by a mould during the frying process. The resultant tortilla chips may have any desired two dimensional plan shape, such as triangular, and any desired three dimensional shape, such as being regularly curved so that a plurality of the tortilla chips are mutually stackable.

Although the invention has particular application to the manufacture of shaped tortilla chips, the method or the present invention may be used to produce a variety of different snack food chip compositions, as well and shapes. For example, the snack food chip may comprise, in addition to corn masa, any cereal-based composition, and may comprise any of, any mixture of, or all of, wheat, barley, rice or any other grain-derived product, as well as any seasoning, either within the cereal-based composition and/or applied as a topical seasoning.

The snack food chips may be provided with other product design features to improve eating quality, for example particular flavourings or texturizing components. The snack food chips may be provided in a consumer acceptable retail format, for example a packaging such as a bag or carton, typically hermetically sealed, which is compatible with a retail sales environment.

Brief Description of the Drawings

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

Figure 1 schematically illustrates a process flow of a method for manufacturing snack food chips in accordance with an embodiment of the present invention; Figure 2 schematically illustrates a cross-section of a snack food chip in accordance with an embodiment of the present invention; and

Figure 3 is a graph illustrating the variation of viscosity with time during RVA analysis for the first, second and third starch components used in accordance with an embodiment of the present invention.

Detailed Description of the Invention

Referring to Figure 1 of the accompanying drawings, there is shown a process flow of a method for manufacturing snack food chips, in particular tortilla chips, in accordance with an embodiment of the present invention.

In the method, in a first step 2 a number of starch-containing components are provided. These comprise a first starch-containing component which includes cold water swelling starch, a second starch-containing component which comprises substantially ungelatinized starch, and a third starch-containing component which comprises corn masa flour.

The third starch-containing component may optionally further comprise at least one further corn ingredient, the further corn ingredient being selected from fresh corn masa, raw corn flour and cooked corn flour or any mixture of any two or more thereof. The fresh corn masa may be added to enhance the corn taste of the chip, although then the additional fresh corn ingredient needs to be provided in the production line. The corn masa typically has a moisture content of about 50 wt% based on the total weight of the corn masa. Typically, the dough does not comprise a fresh corn masa ingredient, because the corn masa flour can provide a good corn taste, and the desired material properties in the dough and chip, and also because the provision of fresh corn can be avoided. The raw corn flour and cooked corn flour can provide some corn taste at lower cost than corn masa and with reduced flavour as compared to corn masa. Such further corn ingredients may, individually or cumulatively, be included in the dough in a weight amount which is less than the weight of the corn masa flour.

In a second step 4 a dough is formed from a mixture of the first, second and third starch- containing components and added water. The dough is typically formed by mixing together the first, second and third starch-containing components to form a dry mix, and then mixing the dry mix with added water, and preferably an emulsifier, to form the dough. Typically, the dough is formed at a temperature of up to 30 °C, optionally from 5 to 20 °C, further optionally from 10 to 15 °C. Typically, the dry mix has a moisture content of from 5 to 20 wt% water in the dry ingredients (i.e. without addition of any added water in liquid form, which is later added to form the dough), optionally from 10 to 12 wt water, based on the weight of the dry mix. Typically, when the dry mix is mixed with the added water, and optional emulsifier, to form the dough the dry mix has a temperature of from 5 to 30 °C, optionally from 5 to 25 °C, and the added water has a temperature of from 5 to 15 °C, optionally from 7 to 12 °C, further optionally from 8 to 1 1 °C. Typically, the dry mix is mixed with the added water and emulsifier to form the dough for a period of from 3 to 30 seconds, typically from 5 to 30 seconds.

Typically, the dough comprises from 35 to 75 wt% corn masa flour, from 10 to 40 wt% of the second starch-containing component, and from 5 to 30 wt% of the first starch-containing component, each based upon the weight of the dry ingredients of the dough.

The cold water swelling starch of the first starch-containing component forms a gel matrix in the dough. The dough preferably comprises from 5 to 20 wt%, more preferably from 10 to 15 wt%, typically about 12 wt%, of cold water swelling starch in the first starch-containing component, based upon the weight of the dry ingredients of the dough.

Typically, the first starch-containing component is selected from a pre-gelatinized cereal flour, a pre-gelatinized starch derivative, or any mixture thereof. The component including cold water swelling starch may be at least one selected pre-gelatinized cereal flour selected from corn, wheat, barley, rice, spelt, or any other grain-derived product, or any mixture thereof. Preferably, the component including cold water swelling starch is a pre-gelatinized corn flour.

The dough preferably comprises from 15 to 30 wt%, more preferably from 20 to 30 wt%, typically about 25 wt%, of the second starch-containing component, based upon the weight of the dry ingredients of the dough. The second starch-containing component is selected from tapioca starch and corn starch or a mixture thereof and preferably comprises tapioca cook-up starch and/or waxy corn cook-up starch.

The dough preferably comprises from 45 to 70 wt%, more preferably from 50 to 65 wt , corn masa flour, based upon the weight of the dry ingredients of the dough.

Typically, the corn masa flour has a particle size falling at least partly within the range extending from a fine particle corn masa, in which at most 30 wt% of the fine particle corn masa is retained on a 500 μπι sieve and at least 25 wt% of the fine particle corn masa passes through a 250 μπι sieve, to a coarse particle corn masa, in which at least 6 wt% of the coarse particle corn masa is retained on an 850 μηι sieve and at most 35 wt% of the coarse particle corn masa passes through a 250 μηι sieve.

Preferably, the corn masa flour is a mixture of two flours having respective particle sizes. Typically, the mixture comprises from 20 to 45 wt%, for example from 30 to 40 wt%, of a first corn masa and from 55 to 80 wt%, for example from 60 to 70 wt%, of a second corn masa, each wt% being based on the weight of the corn masa flour. The first corn masa preferably has a particle size range in which 0 wt% of the first corn masa is retained on a 2000 μπι sieve, at most 11 wt% of the first corn masa is retained on an 841 μπι sieve and at most 32 wt% of the first corn masa passes through a 149 μιη sieve, and the second corn masa preferably has a particle size range in which 0 wt% of the second corn masa is retained on a 2000 μπι sieve, at most 22 wt% of the second corn masa is retained on an 841 ιη sieve and at most 26 wt% of the second corn masa passes through a 149 μπι sieve.

The cold water swelling starch has a peak viscosity at a temperature of less than 50 °C. The second starch-containing component has a peak viscosity at a temperature of from 50 to 80 °C, optionally from 60 to 70 °C. The third starch-containing component has a peak viscosity at a temperature of greater than 80 °C. In each case, the viscosity is measured by a rapid viscosity analyser (RVA) in excess water having a weight of water which is 3 times the weight of the third starch-containing component. In particular, it this specification the viscosity was measured on a Perten Instruments RVA 4500 rapid viscosity analyser and Thermocline for Windows (TCW) software as described at http://www.perten.com/products/rapid-visco- analyser-rva/features-and-benefits/), using a stirring speed of 960 rpm for the first 10 seconds and then 160 rpm thereafter. The sample to be tested was corrected for moisture content using the formula: Compensated Sample Weight = (actual (uncompensated) sample weight x 100)/(100 - wright % moisture content of sample) where the actual (uncompensated) sample weight is 3 grams. The weight of the water used for the rapid viscosity analysis was (28 grams - actual (uncompensated) sample weight in grams).

Figure 3 is a graph illustrating the variation of viscosity with time during RVA analysis for the first, second and third starch components used in accordance with an embodiment of the present invention.

In Figure 3, each of (i) the pregelatinized corn flour, (ii) the tapioca starch and (iii) the corn masa flour were individually subjected to RVA analysis. The viscosity (left-hand y axis) was measured over time (x-axis) and the respective sample was subjected to the temperature profile indicated (right-hand y axis).

It can be seen that (i) the pregelatinized corn flour has a viscosity peak when the temperature is below 50 °C (ii) the tapioca starch has a viscosity peak when the temperature is above 50 °C and below 80 °C and (iii) the corn mas a flour has a viscosity peak when the temperature is above 80 °C (in fact, the corn masa did not peak even when the temperature profile attained a maximum temperature of 95 °C). Each of these peaks is representative of the gelatinization temperature or peak water absorption of the respective starch.

In some embodiments of the present invention, the dough further comprises from 5 to 20 wt%, more preferably from 10 to 15 wt%, based upon the weight of the dry ingredients of the dough, of at least one cereal flour selected from wheat, barley, rice, spelt, or any other grain-derived product, or any mixture thereof. Other ingredients known for use in snack food chips, in particular tortilla chips, may be incorporated into the dough, typically into the dry mix.

In the most preferred embodiments of the present invention, the dough does not comprise a fresh corn masa ingredient.

The dough preferably comprises from 25 to 35 wt% added water, typically from 25 to 30 wt% added water, based on the weight of the dough. The dough further comprises from 0.2 to 1 .5 wt%, more preferably from 0.2 to 0.5 wt% of an emulsifier, based on the weight of the dough. Preferably, the weight ratio of the added water: emulsifier in the dough is from 25: 1 to 200: 1, more preferably from 50: 1 to 150: 1 , yet more preferably from 75: 1 to 125: 1. Typically, the emulsifier is adapted to bind to free starch and optionally comprises or is a monoglyceride- diglyceride emulsifier comprising a mixture of at least one monoglyceride and at least one diglyceride, optionally the monoglyceride-diglyceride emulsifier comprising or consisting of a food additive having E-number E471. The monoglyceride-diglyceride emulsifier may be added to the dough as a liquid or, less preferably, as a solid, and when added as a liquid is optionally melted (for example at a temperature of about 55 °C) or then mixed with a vegetable oil, such as rapeseed oil or sunflower oil, in particular high oleic acid sunflower oil (HOSO), and the liquid emulsifier/oil mixture is then added to the dough. However, it is preferred to add the monoglyceride-diglyceride emulsifier to the dough as a liquid but not in an oil vehicle, since additional oil tends to decrease sheet cohesiveness and the resultant chips may have an increase incidence of through-holes and cracks or chip breakage. In the preferred monoglyceride-diglyceride emulsifier, the monoglyceride component functions to complex to the free starch, which controls blister formation and the diglyceride component functions to reduce the melting temperature of the monoglyceride-diglyceride emulsifier so that it can more readily be added in the form of a liquid. The monoglyceride component is provided in a concentration which is sufficiently high to control blister formation but not so high that so much free starch has been complexed that there is insufficient free starch remaining in the dough for expansion of the second starch-containing component, for example tapioca starch, to cause expansion of the starch matrix during frying.

After formation of the dough, in a third step 6 a dough sheet is formed from the dough and then in a fourth step 8 a plurality of dough pieces are cut from the dough sheet. Preferably, the dough pieces have a thickness of from 0.5 to 1.5 mm, typically from 0.6 to 1 mm. In preferred embodiments of the invention, the dough sheet is formed in a sheeting apparatus at a linear speed for the sheet of from 20 to 60 linear metres/minute, optionally from 30 to 50 linear metres/minute. High speed sheeting to form a thin dough sheet is possible because the dough has high cohesiveness, and does not rip, tear or form holes during sheeting. This is a very high speed sheeting operation as compared to the typical manufacture of tortilla chips of similar sheet thickness since traditional tortilla chip dough, including a high proportion of fresh corn masa, has low cohesion, and so linear sheet speeds are typically only 15 linear metres/minute or less.

The dough pieces are two-dimensionally pre-shaped, and cut into desired two-dimensional shape and dimensions. Initially the dough pieces are typically substantially planar and flexible. The dough pieces may be regularly shaped, for example being triangular, square, rectangular, elliptical, etc., or be irregularly shaped. Typically, the dough pieces have a surface area of from 1000 to 2500 mm ² and a maximum dimension of from 30 to 100 mm.

Subsequently, in a fifth step 10 the dough pieces are cooked to form a plurality of snack food chips. Preferably, the cooking comprises or consists of frying and the frying temperature is from 160 to 200 °C, optionally from 170 to 190 °C, further optionally about 180 °C. The frying time is from 15 to 30 seconds, optionally from 16 to 25 seconds, further optionally from 18 to 23 seconds.

Most preferably, the cooking consists of frying and there is no toasting step prior to the frying step. Alternatively, other cooking techniques apart from frying, such as baking, microwaving, etc. may be used instead of frying. The dough pieces may be shaped against a mould during frying so that the snack food chips are three-dimerisionally shaped with a preset shape, for example as disclosed in US-A- 2008/0044534. The snack food chips made according to the present invention may be shaped and dimensioned so as to be suitable for use together with a dip, such as a salsa composition, cream cheese, avocado composition, etc. which are well known in the snack food art.

For the manufacture of tortilla chips, it is known to prove the dough prior to frying. In alternative embodiments therefore, the shaped dough pieces may be conveyed through a proving chamber in which the shaped dough pieces are subjected to controlled temperature and humidity to prove the dough prior to cooking, as is generally known to those skilled in the art of making tortilla chips.

The first starch-containing component includes cold water swelling starch which forms a gel matrix for the dough to provide a sheetable dough that can be formed at a low temperature, for example at about room temperature or lower.

In the preferred embodiments an emulsifier is present in the dough which is adapted to bind to free starch. For example, the emulsifier comprises or is a monoglyceride-diglyceride emulsifier comprising a mixture of at least one monoglyceride and at least one diglyceride, optionally the monoglyceride-diglyceride emulsifier comprising or consisting of a food additive having E- number E471. The emulsifier can mop up and bind to free starch in the dough. The lower the free starch, the lower the expansion on frying and the lower the blister formation. The monoglyceride-diglyceride emulsifier therefore can control the level of expansion and blistering. The second starch-containing component, for example, tapioca starch, is uniformly distributed throughout the starch matrix, which in turn enhances the uniform formation of blisters during cooking.

The cold water swelling starch is the only starch component of the first, second and third starch components which absorbs water prior to cooking of the dough. At the start of cooking, the second, cook-up, starch, for example tapioca starch, starts to absorb water because it has a higher peak viscosity RVA temperature than the cold water swelling starch but a lower peak viscosity RVA temperature than the corn masa. The corn masa therefore does not absorb water because the water is preferentially absorbed by the tapioca starch. When the dough is cooked, the dough is heated to a temperature above the peak viscosity RVA temperatures of both of the second and third starch-containing components. When the second starch-containing component has a peak viscosity RVA temperature below the peak viscosity RVA temperature of the corn masa, the second starch-containing component, for example tapioca and/or corn starch, rapidly absorbs water from the dough at the elevated cooking temperature, gelatinizes and expands in volume due to the generation of steam. The gelatinization of the second starch-containing component occurs preferentially to the viscosity increase of the corn masa of the third starch- containing component, which has a higher peak viscosity RVA temperature, and so the water in the dough is absorbed by the second starch-containing component, leaving the corn masa of the third starch-containing component substantially unincreased in viscosity and with low water absorption. The corn masa forms a substantially uniform distribution of particles in the starch matrix. The corn masa particles can provide a tortilla chip taste and crunch to the chip.

Since the second starch-containing component is distributed homogeneously throughout the dough, the gelatinization occurs throughout the dough to form an expanded starch matrix together with the first starch-containing component. The expanded matrix forms a light and crunchy texture. The substantially uniform gelatinization provides a plurality of nucleation sites for steam generation as the dough is rapidly dehydrated during cooking. The steam generated forms a substantially uniform array of a plurality of blisters, of substantially uniform size distribution, on opposite surfaces of the chip. Steam generation does not tend to occur at the corn masa particles, which may otherwise cause a non-uniform blister morphology and may cause local stresses in the matrix which could form through-holes or cracks in the cooked chip.

As illustrated in Figure 2, which is not to scale, the resultant snack food chip 20, preferably a tortilla chip, comprises a starch matrix 22 composed of at least one gelatinized and expanded starch, and a plurality of particles 24 distributed in the starch matrix 24. The particles 24 are composed of a third starch-containing component which comprises corn masa which is substantially ungelatinized. The starch matrix 22 forms a continuous wall 26 without through- holes or cracks extending therethrough. The snack food chip 20 has a wall thickness of from 0.5 to 1.5 mm. The snack food chip 20 has having opposite major surfaces 28, 30 which have a plurality of blisters 32 thereon, each blister 32 extending outwardly on both opposite major surfaces 28, 30.

The blisters can readily be detected visually using the naked eye, because of their size. The blisters are aesthetically pleasing on the surfaces of a tortilla chip. For the blisters, the maximum width dimension is typically 1.2 mm and the minimum width dimension is typically 0.5 mm (any smaller sized blisters are essentially not visible to the naked eye). The total number of the various sizes of blisters can readily be detected using a 3-D scanner and a blister number per unit area can be calculated. Since each blister extends outwardly on both surfaces, the blister number per unit area is the number per unit area of one surface of the chip.

In preferred embodiments, for a sample of 6 randomly selected chips, the blisters 32 have a mean total number of blisters per cm ² of the opposite major surfaces 28, 30 of from 0.92 to 1.20, preferably from 1.00 to 1.20, with the blisters 32 having a maximum width of 1.2 mm. Typically, for the sample of 6 randomly selected chips, the blisters 32 include a mean total number of blisters 32 having a maximum width of less than 0.5 mm of from 0.63 to 0.83, preferably from 0.68 to 0.78, blisters per cm ² , and a mean total number of blisters 32 having a maximum width of from 0.5 to 1.2 mm of from 0.25 to 0.43, preferably from 0.30 to 0.38, blisters per cm ² .

In a random population of 100 of the tortilla chips produced according to preferred embodiments of the present invention, more than 90% by number have a continuous wall 26 without through-holes or cracks extending therethrough.

Examples

The present invention is now illustrated further with reference to the following non-limiting Examples.

Example 1

Example 1 produced a tortilla chip using the ingredients listed in Table 1.

Table 1

In Example 1, as listed in Table 1 the ingredients of the dry mixture, namely the flour components comprising corn masa flour and, as a cold water selling starch, the pregelatinized corn flour, the dry additives comprising tapioca starch, black bean flake and dry sunflower lecithin, were mixed to form a dry mixture.

Separately, an emulsifier ingredient was formed by melting a monoglyceride-diglyceride emulsifier, in particular E471 , by heating the solid emulsifier at a temperature of 55 °C, and then mixing the molten emulsifier with rapeseed oil. The emulsifier ingredient comprised 50 wt% monoglyceride-diglyceride emulsifier and 50 wt% in rapeseed oil, each based on the weight of the emulsifier ingredient.

The dry mixture and the emulsifier ingredient were mixed together with the added water to form a dough. The dry mixture has a temperature of 20 to 25 °C, the added water had a temperature of 2 to 10 °C, and the resultant dough mixture was formed at a temperature of 10 to 15 °C. The dough was mixed for less than 5 seconds.

The resultant dough was sheeted through a dough sheeter to a thickness of 0.7 mm. The dough sheet was formed in a sheeting apparatus at a linear speed for the sheet of from 30 to 50 linear metres/minute.

The dough sheet was cut into triangular tortilla chip-shaped dough pieces which were then fried in sunflower oil at 185 °C for a period of about 25 seconds, and then topically seasoned. The resultant tortilla chips had a moisture content of 1.5 to 2.0 wt%, based on the total weight of the tortilla chips.

The resultant tortilla chips had a crispy and crunchy texture. In particular, the opposite surfaces of the tortilla chips had a uniform distribution of blisters. The blisters are formed by steam which is rapidly generated during the frying process. Without being bound by any theory, it is believed that the steam is formed substantially uniformly throughout the dough matrix because the ungelatinized corn masa particles act as initiation points from steam formation. Since there is a uniform distribution of corn masa particles throughout the dough, the steam generation is correspondingly uniform, and a large number of substantially similar-sized blisters is formed on the surfaces of the chip. Also, the pregelatinized corn flour and the tapioca starch provide a starch matrix which is gelatinized in the frying process, and the starch matrix can be substantially uniformly deformed to form the distribution of blisters. The liquid emulsifier in the starch matrix is also believed to assist in achieving a uniform blister distribution and an expanded starch matrix in the resultant tortilla chip. The tortilla chip also did not exhibit any holes or cracks extending through the thickness of the tortilla chip. There was a continuous expanded starchy matrix, with a distribution of substantially unexpanded corn masa particles throughout the matrix. The tortilla chips had a good corn taste.

The corn masa flour was a mixture of two flours having respective particle sizes. In this recipe the corn masa comprised 65% of finer corn masa flour, the US #2 corn masa flour, and 35% of coarser corn masa flour, the US #9 corn masa flour, each based on the weight of the corn masa flour. The finer corn masa flour had a particle size range in which 0 wt% of the corn masa is retained on a 2000 μπι sieve, at most 1 1 wt% of the corn masa is retained on an 841 μηι sieve and at most 32 wt% of the corn masa passes through a 149 μιη sieve. The coarser corn masa flour had a particle size range in which 0 wt% of the corn masa is retained on a 2000 πι sieve, at most 22 wt% of the corn masa is retained on an 841 μπι sieve and at most 26 wt% of the corn masa passes through a 149 μπι sieve.

In this recipe the weight ratio of added water: liquid emulsifier was 30: 1.

The corn masa flour and the liquid emulsifier were both found to control the amount and uniformity of blistering on the surface of the tortilla chips. It was found that increasing the proportion and amount of coarse corn masa flour particles tended to increase the uniformity of blistering and a reduction in the occurrence of individual large blisters. The liquid emulsifier tended to increase the uniformity of blistering on the surface of the tortilla chips.

The black bean flake component, which is known for use in tortilla chips, was added to provide a distribution of fine back particles in the tortilla chips to provide increases texture and visual contrast. The dry sunflower lecithin was added to assist release of the sheet from the sheeting rolls.

Example 2

Example 2 produced a tortilla chip using the ingredients listed in Table 1. The processing was as set out above for Example 1. The tortilla chip had a good level of blistering, but slightly less uniform, generally larger and with a reduced number per unit area as compared to Example 1. It is believed that the reduced concentration of the coarser corn masa flour led to the reduced blister uniformity in size and distribution.

Example 3 Example 3 produced a tortilla chip using the ingredients listed in Table 1. The processing was as set out above for Example 1. The tortilla chip had a good level of blistering, but less uniform, generally larger and with a reduced number per unit area as compared to Example 1.

Example 4

Example 4 produced a tortilla chip using the ingredients listed in Table 1. The processing was as set out above for Example 1. The tortilla chip had a uniform mid-size blisters, but less uniform, generally larger and with a reduced number per unit area as compared to Example 3. Also, the chip matrix was less expanded as compared to Example 3, which is believed to result from a lower concentration of tapioca starch in the dough.

Example 5

Example 5 produced a tortilla chip using the ingredients listed in Table 1. The processing was as set out above for Example 1. The tortilla chip had some blisters, but reduced as compared to Example 3. Also, the chip matrix was less expanded as compared to Example 3, even with a slightly higher concentration of liquid emulsifier in the dough, which lower expansion is believed to result from a lower water: liquid emulsifier weight ratio of 25: 1 as compared to 33: 1 for Example 3.

Comparative Example 1

Comparative Example 1 produced a tortilla chip using the ingredients listed in Table 1. The processing was as set out above for Example 1. The recipe excluded tapioca starch. The tortilla chip had a poorly expanded matrix, which was unacceptable.

Thus there was no component comprising a "cook-up" starch which was substantially ungelatinized in the dough but during frying gelatinizes and expands in volume. This Comparative Example illustrate that such a "cook-up" starch provides the required expanded starch matrix in the tortilla chip.

Various other modifications to the present invention will be readily apparent to those skilled in the art.