PREPARATION OF SNACK FOOD PELLETS.

Abstract

A method for preparing a starch-based snack pellet for the production of an expanded snack food, the method comprising the steps of: feeding a first starch ingredient into a cooking device; introducing mechanical and thermal energy into the cooking device in order to cook and gelatinize the first starch ingredient in the cooking device, thereby providing a processed starch component; adding a potato starch ingredient comprising potato starch sourced from potato to the processed starch component to provide a starch mixture; and forming the starch mixture into pellets by extrusion. As stated, this is a starch-based snack pellet for the production of an expanded snack food.

Description

PREPARATION OF SNACK FOOD PELLETS FIELD OF INVENTION The present invention relates to a method of making a starch-based snack pellet to produce an expanded snack, a starch-based snack pellet to produce an expanded snack, and an expanded snack produced from a starch-based snack pellet. BACKGROUND OF THE INVENTION The use of starch-based pellets to produce snack foods, typically in the form of chips, is well known in the field. The pellet is produced by extrusion. In subsequent cooking, whether by frying, baking, microwaving, extruding, or popping, the pellet expands to produce a porous, low-density, expanded snack food. The pellets contain a high proportion of starch. It is essential that, when subjected to rapid cooking at high temperature, the starch expands to produce a light and highly porous structure in the expanded snack food, which is substantially homogeneous and substantially avoids the presence of unexpanded glassy regions. Many snack food products are produced from pellets that have a starch content comprising a mixture of starches to provide the desired properties in the resulting expanded snack food. For example, many pellets include a significant proportion, up to 100% by weight, of starch in the total starch content. Potato starch can provide characteristic properties to the expanded snack food, related to sensory experience, mouthfeel, crispness, crunchiness, degree of expansion, cell size, and cell wall thickness, etc. When a mixture of starches is used, for example to provide a modified sensory experience, or to use a mixture of a potato starch and a non-potato starch to provide a less expansive pellet or a pellet that is preferred for processing in a country where potatoes are not locally grown by using a high proportion of locally grown ingredients, the mixture may combine potato starch and starch from cereals (such as wheat, corn, barley, rice, etc.) and / or roots (such as tapioca or sweet potato) and / or pulses (such as peas or beans). One problem in making pellets from a mixture of potato starch and non-potato starch is that, during pellet production, to ensure the mixture is processed sufficiently to allow for uniform expansion during subsequent expansion, the potato starch may be annealed. The effect of such annealing is that the desired potato characteristics are partially or completely lost in the resulting expanded snack food. Furthermore, such annealing can inhibit or prevent the pellet from producing an expanded snack food, such as a chip, with the light, fluffy expanded structure required by consumers. BRIEF DESCRIPTION OF THE INVENTION The present invention aims to solve this problem of the production of known expanded snack foods produced from pellets that have a mixture of potato starch (starches) and starch (starches) that are not from potato. Accordingly, the present invention provides a method for preparing a starch-based snack food pellet for the production of an expanded snack food, the method comprising the steps of: a. feed a first starch ingredient into a cooking device; b. introduce mechanical and thermal energy into the cooking device in order to cook and gelatinize the first ingredient starch in the cooking device, thereby providing a processed starch component; c. adding a potato starch ingredient comprising sourced potato starch to the processed starch component to provide a starch mixture; and d. form the starch mixture into pellets by extrusion. Typically, the first starch ingredient comprises or consists of 25 originating cereal starch, optionally in combination with one or more originating root starches (such as tapioca or sweet potato) and an originating legume starch (such as pea or bean). The present invention further provides a starch-based snack food pellet for making an expanded snack food, the pellet comprising a starch matrix formed from a mixture of starches, wherein the mixture comprises 40 to 70% by weight of a gelatinized starch that is not potato, 20 to 40% by weight of an original potato starch and 20 to 70% by weight of a gelatinized potato starch, wherein each weight percentage (% wt) is based on the weight of the starch mixture. Typically, non-potato starch comprises or consists of cereal starch, optionally in combination with one or more root starches (such as tapioca or sweet potato) and a native legume starch (such as pea or bean). The present invention further facilitates an expanded snack food produced from the starch-based snack food pellet according to the present invention. The expanded snack food can optionally be fried, baked, microwaved, extruded, or popped directly. Preferred attributes of all these aspects of the present invention are defined in the dependent claims. The modalities of the present description will now be described, by way of example only, with reference to the attached figures, in which: BRIEF DESCRIPTION OF THE FIGURES Figure 1 is a schematic process flow of a method for making a snack food pellet for making an expanded snack food of 5 according to an embodiment of the present invention; Figure 2 is a schematic side view of an apparatus for carrying out the process flow of the method in Figure 1; Figures 3a to 3d are photomicrographs of a cross-section through pellets that have the same starch-based composition, but with different proportions of the original potato starch processed directly by the former / extruder and the cooking device in the method of Figure 1: Figure 4 is a bar graph showing the relationship between the enthalpy during a starch gelatinization test of pellet compositions that have a starch-based composition, but with different proportions of the original potato starch being processed directly by the former / extruder and the cooking device in the method of Figure 1; and Figure 5 is a graph showing the relationship between heat flow and temperature during a starch gelatinization test of pellet compositions that have a starch-based composition but with different proportions of the original potato starch being processed directly by the former / extruder and cooking device in the method of Figure 1. DETAILED DESCRIPTION OF THE INVENTION With reference to Figure 1, a schematic flow diagram of the process for a method of preparing a starch-based snack food pellet for the production of an expanded snack food according to a preferred embodiment of the present invention is shown. Figure 2 schematically shows the apparatus used in the method of Figure 1. As shown in Figures 1 and 2, in a first step 2 of the method, a first starch ingredient 4 is fed into the cooking device 6. The first starch ingredient preferably comprises or consists of source starch. Preferably, the first starch ingredient comprises or consists of source cereal starch, optionally in combination with one or more source root starches (such as tapioca or sweet potato starch) and a source legume starch (such as pea or bean starch). Typically, the cooking device Θ is a mixer having an inlet for thermal and mechanical energy, or a thermal cooking apparatus adapted to introduce a jet of steam into the cooking chamber. Both devices are known in the art of making snack food pellets. In a second stage 10, mechanical and thermal energy is introduced into the cooking device 6 to cook and gelatinize the first ingredient, starch 4. Mechanical energy is provided by mechanical mixing. Thermal energy is provided by steam. Preferably, both mechanical mixing and steam are applied to the first ingredient, starch 4. Typically, mechanical energy is provided by mixing the cereal starch ingredient 4 at a shear rate of 40 to 100 s⁻¹. Typically, the steam is at a temperature of 157 to 172°C and / or a pressure of 6 to 8 bar. This stage 10 yields a processed starch component 12. Typically, the processed cereal starch component 12 comprises cereal starch in which 40 to 80% by weight of the cereal starch has been gelatinized, as measured by an enzymatic method, for example, the Kansas method, which is known in the art. During step 10, the average molecular weight of the original starch is reduced. After step 10, the original starch in the processed starch component 12 typically has a viscosity of 100 to 150 Pa. sy / o a melting point less than 150 °C, for example, from 50 to 100 °C, according to measurements by differential scanning calorimetry (DSC). Therefore, in a third stage 20, a potato starch ingredient originating 22 15 is added to the processed starch component 12 to provide a starch mixture 24. The potato starch ingredient 22 preferably comprises or consists of a first potato starch originating 26. The addition can be made inside or outside the cooking device 6, but the potato starch ingredient 22 is not processed inside the cooking device 6 as described for the first starch ingredient 4. Before ingredients 12 and 22 enter extrusion / forming, they are preferably mixed with water in a mixer 36, such as a paddle mixer, during a mixing stage 38 to form a starch / water mixture having a moisture content of 30 to 50% by weight, based on the total weight of the starch / water mixture. Finally, in a fourth stage 30, the starch mixture 24 is formed into pellets by extrusion in a former / extruder 34. Typically, the starch mixture is mixed and extruded within a temperature range of 50 to 80 °C and / or at a pressure of 20 to 130 bar. Typically, the starch mixture is mixed and extruded at a shear rate of 3000–5000 s⁻¹ in the press / barrel region of the screw extruder press and 500–700 s⁻¹ at the nozzle of the extruder. After the fourth stage 30, the pellets 32 typically have an apparent bulk density of 200 to 800 kg / m³. Preferably, the pellets 32 have a water content 10 of from 9 to 13% by weight based on the pellet weight. With regard to the starch mixture in pellets 32... pellets 32 comprise from 40 to 70% by weight of a gelatinized non-potato starch derived from the first ingredient starch 4, for example, cereal starch, from 10 to 40% by weight of a potato starch originating from 15 and from 20 to 70% by weight of a gelatinized potato starch, each % by weight being in weight of the starch mixture. According to the illustrated embodiment of the present invention, in the first stage 2, a second potato starch originating from 8 is introduced into the cooking device 6, 20 in addition to the other ingredient, cereal starch 4. Typically, the second potato starch originating from 8 comprises from 10 to 30% by weight of the starch mixture produced in the fourth stage 30, by weight of the starch mixture. When the second starch originating from 8 is used, the first and second potato starches originating from 26, 8 are supplied from a single common source and are divided between being added, respectively, at the outlet and upstream 25 of the cooking device 6 and are in a weight ratio of from 1:3 to 4:1. Furthermore, according to the illustrated embodiment of the present invention, in the third stage 20 the potato starch ingredient 22 further comprises a pregeiatinized potato starch 28. The pregeiatinized potato starch typically comprises dehydrated potato 5, for example, as potato granules and / or potato flakes, but may be present in the form of a powder or flour semolina. The pregeiatinized potato starch 28 can be added to the former / extruder 34 or to the mixer 36. The starch-based snack food pellet 32 ​​produced by the method comprises a starch mixture formed from a starch mixture. According to the illustrated embodiment of the present invention, the starch mixture comprises, wherein each % by weight is based on the weight of the starch mixture: a. 40 to 70% by weight of a gelatinized starch that is not potato starch, which has been produced from the first ingredient starch 4 and has been cooked and gelatinized in the cooking device 6; b. 10 to 40% by weight of an originating potato starch, which has been provided by the first originating potato starch 26, in the outlet line of the cooking device 6 and thus has not gelatinized in the cooking device and remains substantially crystalline; and c. 20 to 70% by weight of a gelatinized potato starch, which has been produced from the combination of the second originating potato starch 8 added to, and gelatinized in, the cooking device 6 and the pregelatinized potato starch 28 which is added to the former / extruder 34 in the outlet line of the cooking device When the first and second originating potato starch 26, 8 has been added as described above, typically with respect to the starch mixture in the pellets 32, and has been produced in the fourth stage 30, the starch mixture comprises 40 to 70% by weight of gelatinized non-potato starch, derived from the first starch ingredient 4, for example cereal starch, give 10 to 40% by weight of a parent potato starch, derived from the first parent potato starch, 10 to 30% by weight of a first gelatinized potato starch, derived from the second parent potato starch, and 10 to 40% by weight of a second gelatinized potato starch, derived from pregelatinized potato starch, each % by weight being by weight of the starch mixture. The 32 pellets can be used to make a snack food that expands when fried. Baking, microwaving, popping. Each of these methods of expanding pellets is known per se to people skilled in the technique of preparing snack food. The present invention is based at least in part on the inventors' finding that when different starches are processed to form a starch-based snack food pellet, the starches tend to have different original properties prior to processing to form a pellet, different processing parameters to form a pellet, and different materials and structural properties in the resulting pellet, the pellet properties of which are manifested in the properties of the resulting expanded snack food. In particular, potato starch originates tend to gelatinize easily, compared to cereal starch originates, when subjected to heat and moisture, and potato starch originates is frequently used as a starting ingredient in pellet extrusion in a pregelatinized form. When potato starch originates are subjected to low thermal energy / low shear mechanical extrusion, the molecular weight of the potato starch is substantially preserved. Potato starch tends to have a relatively low melting point, and thus when the starch is subjected to high cooking temperatures, for example, in a fryer, the potato starch undergoes material transformation, specifically melting to provide a starch melt which provides some degree of expansion.The fusion of potato starch provides a characteristic combination of size, shape, and cell void space distribution, and cell wall thickness, which provides a typical sensory characteristic for expanded snacks incorporating high concentrations of potato starch. In contrast to potato starch, some non-potato starches, such as cereal (or legume or root) starch, when subjected to the same heat and moisture conditions, tend to become less gelatinized. Specifically, cereal starch, compared to potato starch, tends to require high thermal energy / high-shear mechanical extrusion to achieve a corresponding proportion of gelatinized starch. The molecular weight of cereal starch is typically damaged, or significantly reduced, by high-shear mechanical extrusion. During frying, the processed, low-molecular-weight cereal starch fuses and exhibits low viscosity, resulting in a high degree of expansion.This produces a very fluffy and light expanded texture, with very large empty cell spaces and thin cell walls. If cereal starch with a relatively high melting point is present in a pellet, there is a chance that the starch may not fuse when subjected to high cooking temperatures, for example, in a deep fryer, leaving unexpanded starch in the snack food, which is undesirable. When both potato starch and cereal starch are combined as ingredients to produce a pellet for subsequent expansion into a snack food, it is difficult to process the ingredients to provide the typical sensory characteristics of expanded snacks incorporating high concentrations of potato starch. Specifically, it is challenging to achieve the desired combination of size, shape, cell void space distribution, and cell wall thickness associated with a high-viscosity potato starch melt. The potato and cereal starch mixture is difficult to process in a common manufacturing sequence that can produce a composite starch melt whose expansion provides a uniform and controlled cell microstructure, and in particular, a uniform combination of size, shape, cell void space distribution, and cell wall thickness. These different behaviors of potato and non-potato starches have been used in the method of the present invention to achieve desired control over the processing of the starch from a mixture of potato and non-potato starches to form a pellet. The properties of the pellet can be easily controlled, and consequently, the properties of the resulting expanded snack food produced from the pellet can also be controlled. According to preferred embodiments of the present invention, the pellets are produced from a mixture of a cereal (or a selection or combination of one or more cereals and / or legumes) and potato. At least one portion of each type of starch ingredient 5 can be processed individually and separately from at least one portion of the other type of starch ingredient and then combined into a starch mixture that is subsequently commonly extruded.This overcomes the problem that some source starches, such as those from cereals and legumes, require much more cooking than source potato starch in order to pre-process their constituent starch 10 prior to extrusion, and the problem that if a starch mixture comprising both potato and non-potato starch is cooked as a whole, if the cereal portion is processed correctly then the potato portion tends to become overcooked and the desired characteristics of the potato in the expanded snack food are lost. According to preferred embodiments of the present invention, instead of processing the starch-containing recipe as a whole using a common cooking and extrusion process, which potentially leaves at least one of the starch components undercooked and / or at least one of the other starch components overcooked, with a consequent negative impact on the quality of the snack food, the different starch ingredients can be processed individually or separately during cooking and then combined before extrusion and shaping of the product. The inventors have found that processing individual starch ingredients, or groups of starch ingredients, can provide greater control over the characteristics of the resulting snack food. In preferred embodiments of the method of the present invention, by adding a mixer with thermal and mechanical energy input and / or a thermal cooking apparatus adapted to introduce a jet of steam into a cooking chamber to a standard pellet processing line, and by incorporating an extruder, greater control over product quality and the characteristics of the snack food produced from the pellets can be achieved. The pellet is produced by a process in which the first ingredient, starch, for example, comprising or consisting of cereal starch, is processed in a cooking device. Mechanical and thermal energy are applied to cook and gelatinize the cereal starch, thereby providing a processed cereal starch component. Following this, a potato starch ingredient is added to the processed cereal starch component to provide a starch mixture, which is then formed into pellets by extrusion. The potato starch is not cooked but rather formed into a pellet by extrusion, and the starch is retained as starch granules within the extruded pellet. In this way, it is substantially unchanged in terms of crystallinity and retains a high molecular weight.In the potato pellet, the original potato starch provides local crystalline regions distributed within the amorphous, and / or minimally crystalline starch formed from gelatinized and cooked potato / cereal starch. Some or all of the total original potato starch is fed directly into the former / extruder, and optionally, a proportion of the total original potato starch can be fed into the cooking device. By controlling the proportion of original potato starch fed directly into the former / extruder, the microstructure of the resulting starch mixture in the pellet can be controlled to provide the desired properties in the resulting expanded snack food. Regarding the total original potato starch supplied to form the pellet, from more than 0 to 100% by weight of the original potato starch is fed directly into the former / extruder, and from 0 to less than 100% by weight of the original potato starch is fed into the cooking device. Figures 3a to 3d are photomicrographs of a cross-section through pellets that have the same starch-based composition, but with different proportions of the original potato starch processed directly by the former / extruder and the cooking device in the method of Figure 1. In Figure 3a, 100% of the original potato starch was processed directly by the former / extruder, and 0% of the original potato starch was processed by the cooker. The resulting microstructure has a high level of potato starch crystallinity and minimal cereal starch crystallinity, with potato starch crystalline regions 50 distributed within the amorphous potato / cereal starch 52. This microstructure is characteristic of a potato starch pellet. In Figure 3d, 0% of the original potato starch was processed directly by the former / extruder, and 100% of the original potato starch was processed by the cooking device. The resulting microstructure has minimal potato starch crystallinity and some cereal starch crystallinity, and the resulting structure is a substantially amorphous, low-crystallization microstructure 54 with a substantially homogeneous composition. During processing in the cooking device, the potato starch was preferentially hydrated and gelatinized compared to the cereal starch, leaving regions 56 with low cereal starch crystallinity within a generally amorphous potato / cereal starch combination 58. In Figure 3b, 67% of the original potato starch was processed directly by the former / extruder, and 33% was processed by the cooking device. In Figure 3c, 20% of the original potato starch was processed directly by the former / extruder, and 80% was processed by the cooking device. These 10 micrographs show that by progressively reducing the proportion of original potato starch processed directly by the former / extruder and increasing the proportion of original potato starch processed through the cooking device, the crystallinity of the potato starch is reduced, which modifies the texture of the pellet and its behavior during expansion. Figure 4 is a bar graph showing the enthalpy relationship during a starch gelatinization test of pellet compositions with a starch-based composition but different proportions of the original potato starch being processed directly by the conformer / extruder and the cooking device 20 in the method of Figure 1. When starch is heated in the presence of water, if the starch gelatinizes, then heat is required to achieve the starch transformation. In Figure 4, for the bar labeled A, all the original cereal starch and the original potato starch have been processed through the cooking device, and thus the starch has gelatinized. When the pellet is tested by heating in the presence of excess water, there is minimal additional gelatinization. The measured enthalpy of the starch is low. In contrast, for bar marked D, all of the original cereal starch and 33% by weight of the original potato starch have been processed through the cooking device, and 67% by weight of the original potato starch has been added directly to the inlet of the former / extruder, and thus a majority of the original potato starch is crystalline in the pellet. When the pellet is tested by heating in the presence of water, there is significant additional gelatinization of the starch from the original potato starch, and the measured enthalpy of starch transformation is high, along with a measured enthalpy of the cereal starch.For bars marked B and C, respectively, 50% or 66% by weight of the original potato starch has been processed through the cooking device, and 50% or 33% by weight of the original potato starch has been added directly at the inlet of the former / extruder. In each case, all of the original cereal starch has been processed through the cooking device. For these graphs, approximately half or a small portion of the original potato starch is crystalline in the pellet. When these pellets are checked by heating in the presence of water, they are compared to the bar. There is additional significant gelatinization of the starch progressively reduced from the original potato starch and the enthalpy measured from the transformation of the starch is progressively reduced, along with a measured enthalpy of the cereal starch. Figure 5 is a graph showing the relationship between heat flow and temperature during a starch gelatinization test of pellet compositions that have a starch-based composition, but with different proportions of the original potato starch being processed directly by the former / extruder and the cooking device in the method of Figure 1. When a starch is heated in the presence of water, if the starch gelatinizes then heat is required to achieve the transformation of the starch, and the gelatinization of the starch is represented by a peak in the heat flow.In Figure 5, for the graph marked A, all the original cereal starch and potato starch have been processed through the cooking device, and thus the starch has gelatinized. When the pellet is tested by heating in the presence of water, there is minimal additional starch gelatinization, and there is a very small peak in the heat flow at a relatively high temperature (above 80 °C), which represents cereal starch gelatinization. In contrast, for the graph marked D, all the original cereal starch and 33% by weight of the original potato starch have been processed through the cooking device, and 67% by weight of the original potato starch has been added directly to the former / extruder inlet, and thus a majority of the original potato starch is crystalline in the pellet.When the pellet is tested by heating in the presence of water, there is significant additional gelatinization of the original potato starch, and there is a large peak in the heat flow at a relatively low temperature (below 80°C), which represents potato starch gelatinization. There is almost no peak in the heat flow at a relatively high temperature (above 80°C), which represents cereal starch gelatinization, because potato starch gelatinization occurs preferentially to cereal starch gelatinization. For graphs labeled B and C, respectively, 50% or 66% by weight of the original potato starch has been processed through the cooking device, and 50% or 33% by weight of the original potato starch has been added directly to the former / extruder inlet. In each case, all of the original cereal starch has been processed through the cooking device.For these graphs, approximately half or a minority of the original potato starch is crystalline in the pellet. When these pellets are tested by heating in the presence of water, they are compared to the graph. There is a progressively reduced peak in heat flow at a relatively low temperature (below 80 °C) which represents gelatinization of potato starch, and there is almost no peak in heat flow at a relatively high temperature (above 80 °C) which represents gelatinization of cereal starch. When the pellet is cooked, during the expansion phase, the pellet components in the starch mixture heat up. The high molecular weight and highly crystalline original potato starch melts to form a high-viscosity melt, while the low molecular weight, low-crystallinity or amorphous gelatinized potato / cereal starch melts to form a low-viscosity melt. The water in the starch evaporates to form steam, which in turn forms the cell voids or pores. The high-viscosity melt tends to provide low expansion and results in a uniform distribution of small cell voids with thick cell walls, whereas the low-viscosity mixture tends to provide high expansion and results in a less uniform distribution of large cell voids with thin cell walls.Crystalline regions have a high glass transition temperature Tg and tend to reduce bubble collapse and coalescence. When a mixture of low- and high-crystallinity starches is present in the pellet, the proportions of crystalline starch and the combination of low-crystallinity / amorphous starch can be varied to modify the resulting expanded microstructure. This can be achieved by gelatinizing the original cereal starch in the cooking device and selecting the proportion of original potato starch that is either added as an input to the cooking device, thus gelatinizing there, or added at the outlet, thus remaining present as original crystalline starch in the pellet. Therefore, the starch crystallinity in the pellet, and the cell structures in the snack food, can be modified independently of the transformation of the cereal starch in the cooking device. The starch matrix in the pellets of the preferred embodiments of the present invention therefore comprises a first relatively crystalline starch composition, consisting solely or primarily of sourced potato starch, and a second relatively amorphous starch composition, comprising cereal starch and optionally potato starch, the amorphous starch component being more amorphous than the crystalline starch and the crystalline starch being more crystalline than the amorphous starch component, which have been combined together to form the starch matrix. The first starch composition typically comprises 10 to 40% by weight based on the weight of the starch matrix, and the second starch composition typically comprises 10 to 30% by weight based on the weight of the starch matrix. Various modifications to the present invention will be readily apparent to those skilled in the art.

Claims

1. A method for preparing a starch-based snack food pellet for the preparation of an expanded snack food, the method comprising the steps of: a, feeding a first starch ingredient into a cooking device; b, introducing mechanical and thermal energy into the cooking device in order to cook and gelatinize the first starch ingredient in the cooking device, thereby providing a processed starch component; c. adding a potato starch ingredient comprising sourced potato starch to the processed starch component to provide a starch mixture; and d. forming the starch mixture into pellets by extrusion.

2. A method according to claim 1 wherein the ooooion device includes a mixer.

3. A method according to claim 1 or claim 2, wherein the cooking device is a thermal cooking apparatus adapted to introduce a jet of steam into the cooking chamber 4. A method according to any of claims 1 to 3 wherein in step b the mechanical energy is provided by mechanical mixing and / or the thermal energy is provided by steam.

5. A method according to claim 4 wherein the steam is at a temperature from 157 to 172 °C and / or at a pressure from 6 to 8 bar.

6. A method in accordance with any of claims 1 to 5 wherein after step b the processed starch component comprises cereal starch with a gelatinization of from 40 to 80%.

7. A method according to any of claims 1 to 6 wherein during step b the average molecular weight of the first starch ingredient is reduced.

8. A method according to any of claims 1 to 7 wherein in step a the first starch ingredient comprises or consists of cereal starch originating therefrom, optionally in combination with one or more originating root starches and a originating legume starch.

9. A method according to any of claims 1 to 8 wherein the first starch ingredient comprises 40 to 70% by weight of the starch mixture produced in step c, by weight of the starch mixture.

10. A method according to any of claims 1 to 9 wherein in step c the potato starch ingredient comprises or consists of a first originating potato starch. 25 11. A method according to claim 10 wherein the first originating potato starch comprises from 10 to 40% by weight of the starch mixture produced in step c, by weight of the starch mixture.

12. A method according to claim 10 or claim 11 wherein, in step a, a second potato starch is introduced into the cooking device, in addition to the first starch ingredient. 5 13. A method according to claim 12 wherein the second originating potato starch comprises from 10 to 30% by weight of the starch mixture produced in the fourth step d, by weight of the starch mixture.

14. A method according to claim 12 or claim 13 wherein the first and second originating potato starch are in a weight ratio of from 1:3 to 4:1, 15. A method conforming to any of claims 10 to 14 wherein in step c the potato starch ingredient further comprises or consists of 15 a pregelatinized potato starch.

16. A method according to claim 15 wherein the pregelatinized potato starch comprises dehydrated potato, optionally in the form of granules and / or flakes.

17. A method according to claim 15 or claim 16 wherein the pregelatinized potato starch comprises from 10 to 40% by weight of the starch mixture produced in step e. 25 18. A method according to any of claims 1 to 17 wherein in step d the starch mixture is mixed and extruded within a temperature range of 50 to 80 °C and / or at a pressure of 20 to 130 bar absolute.

19. A method according to any of claims 1 to 18 wherein the first starch ingredient comprises a corn, wheat, oat, rice or barley ingredient, or a mixture of any two or more of the same.

20. A method according to any of claims 1 to 19 wherein the pellets have an apparent bulk density of from 200 to 800 kg / m3 21. A method according to any of claims 1 to 20 wherein the pellets have a moisture content of from 9 to 13% by weight based on the weight of the pellet.

22. A starch-based snack pellet produced by the method according to any one of claims 1 to 21.

23. The present invention further provides a starch-based snack pellet for the manufacture of an expanded snack food, the pellet comprising a starch matrix formed from a mixture of starches, wherein the mixture comprises 40 to 7.0% by weight of a gelatinized non-potato starch, 20 to 40% by weight of a potato starch originating from potato, and 20 to 70% by weight of a gelatinized potato starch, wherein each weight percent (% by weight) is based on the weight of the starch mixture. A starch-based snack pellet according to claim 23 wherein the pellet has a water content of 9 to 13% by weight.

23. 25 based on the weight of the pellet.

25. A starch-based snack food pellet according to claim 23 or claim 24 wherein the non-potato starch optionally comprises or consists of a cereal starch in combination with one or more root starches and a legume starch.

24.

26. A starch-based snack food pellet according to claim 25 wherein the cereal starch comprises or consists of corn, wheat, oat, rice, or barley starch, or a mixture of any two or more of the same. 10 25.

27. An expanded snack food produced from starch-based snack food pellet in accordance with any of claims 21 to 26.

26.

28. An expanded snack food according to claim 27, which is fried, baked, microwaved, extruded or directly popped.