Edible Skin Analogues - products and processes

Field of Invention

The present invention relates to the field of animal nutrition, primarily but not limited to human nutrition. In particular, the invention relates to products and processes for their formation that may be used to provide plant-based protein. The present invention also relates to extrusion technology and products and processes that relate thereto. In specific embodiments the invention relates to edible skin analogues prepared by extrusion.

Background of the Invention

While animal tissue (mainly meat, but also offal and skin) has been a staple human food source for thousands of years, primarily as a source of protein, growing trends in human health and consumer behaviour have called for a diversified diet. Personal reasons for reducing animal tissue consumption include:

• health reasons - for example increased processed or red meat consumption has been correlated with increased incidence of certain cancers;

• ethical considerations - including animal welfare;

• environmental sustainability - including the impacts of intensive animal farming.

Many consumers now consciously strive to source a growing proportion of their protein needs from non-animal protein sources - indeed the twentieth and twenty-first centuries have seen a rise in health and consumer trends towards plant-based diets.

While there is now a growing range of plant-based dietary choices available to source protein from, there is some consumer resistance in shifting from animal tissue to plant-based options in part due to an underlying desire (perhaps primal desire) for a meaty sensorial experience (including similar taste, appearance, and/or texture). To date very few, if any, plant based offerings can faithfully reproduce the sensorial experience (taste, appearance, and/or texture) of consuming animal tissue.

For some segments of consumers, such a difference in sensorial experience (taste, appearance, and/or texture) is not problematic and can even be desirable. However for a great many people, being able to consume plant-based protein that provides a sensorial experience (taste, appearance, and/or texture) similar to animal tissue is strongly desired. While advances have been made using soy protein in creating a desirable animal tissue-like texture, soy is an allergen and hence inedible for a substantial proportion of the world's population.

The global demand for protein is expected to rise by 20% from 2018 to 2025, in part driven by a significant Asian population having access to greater consumer choice.

Associated with meeting the growing demand for plant-based protein, is the desire to offer such protein in a readily consumable form. Such readily consumable forms are highly desired by certain segments in the consumer market - such as those people participating in physical activities (including: activities without access to refrigeration like hiking; and intense activities like gym users); and those people desiring a ready to use meal ingredient.

Pork cracklings or pork scratchings are terms used to describe a meat snack that is made from pork skins. Pork crackling is a very popular snack/side dish that is consumed around the world. Each country and region have their way of cooking the crackling and have a different name for them but they are commonly pork skin that has been roasted or fried to produce a crispy layer which gives it a characteristic crunch that is desirable.

The composition of fresh pigskin is by weight roughly 35% protein, 22% fat and 43% moisture. The majority of the protein in pigskin exists as collagen which is an insoluble fibrous protein that exists in the extracellular matrix and in connective tissues. When the skin is roasted or fried, the moisture which is trapped in within the collagen matrix evaporates and bursts through the skin creating air pockets.

During the process, the fat also renders out creating lard as a by-product. Once all the moisture escapes and all the fat renders out, the skin is left with mainly just protein which is then denatured resulting in harder skin which creates the crisp texture.

Mexico is one of the largest pork crackling producer and consumer in the world. Their pork rind products are known as chicharrones. They are produced by deep frying pork skin with a small layer of fat still attached to it. In Mexico, chicharrones are served along with many dishes including soup, salsa and taco.

In New Zealand, the cracklings are usually sold in a small individual commercialised packet in supermarkets along with other snack foods and they are often consumed as an accompaniment. Object of the Invention

Singularly, or in addition to any one or more other objects, it is an object of the invention to provide a plant-based protein source having a desirable sensorial experience similar to that of pork crackling.

Singularly, or in addition to any one or more other objects, it is an object of the invention to provide a plant-based protein source having a desirable texture similar to that of pork crackling.

Singularly, or in addition to any one or more other objects, it is an object to provide a plant-based protein source having a desirable appearance similar to that of pork crackling.

Singularly, or in addition to any one or more other objects, or in addition to any other object, it is an object to provide a plant-based protein source having a desirable taste similar to that of pork crackling, such as flavour profile.

Singularly, or in addition to any one or more other objects, it is an object to provide a plant-based protein source in a readily consumable form.

Alternatively, it is an object of the invention to at least provide the public with a useful choice.

Summary of the Invention

In a first aspect the invention provides a mixture for use in the formation of an edible skin analogue, the mixture including:

(i) maize grits;

(ii) rice flour;

(iii) pea protein;

(iv) pea fibre; and

(v) salt.

In a second aspect the invention provides an edible skin analogue produced by extrusion of water and a mixture including: (i) pea protein;

(ii) maize grits and/or rice flour;

(iii) pea fibre.

In a third aspect the invention provides an extrusion process for making an edible skin analogue, the process including the step of: a) introducing into an extruder a mixture including:

(i) pea protein;

(ii) maize grits and/or rice flour;

(iii) pea fibre; b) combining the mixture with water; c) extruding the combined mixture and water through an extruder die.

In a fourth aspect the invention provides an edible skin analogue extrusion produced by the extrusion process of the third aspect.

In a fifth aspect the invention provides an extruder die for incorporation in an extruder, the extruder die having an elongate aperture having a major axis and a minor axis, the elongate aperture having a first end and a second end on the major axis, wherein the width parallel to the minor axis of the elongate aperture at some point proximate to the first end is greater than the width of the elongate aperture at its middle on the major axis.

In a sixth aspect the invention provides an extruder die for incorporation in an extruder, the extruder die having an elongate aperture having a length dimension and a width dimension, wherein the aperture is:

• between about 10 mm and about 20 mm in length, such as about 15 mm in length;

• between about 1 mm and 2 mm in width for the majority of the length of the aperture, such as about 1.5 mm in width for the majority of the length of the aperture; and wherein at each end of the elongate aperture the aperture includes a portion that is between about 2 mm and about 5 mm in width, such as about 3.0 mm in width.

In a seventh aspect the invention provides an extrusion process for making an edible skin analogue, the process including the step of: a) introducing into an extruder a mixture including: (i) pea protein;

(ii) maize grits and/or rice flour;

(iii) pea fibre; b) combining the mixture with water; c) extruding the combined mixture and water through an extruder die, the extruder die having an elongate aperture having a major axis and a minor axis, the elongate aperture having a first end and a second end on the major axis, wherein the width parallel to the minor axis of the elongate aperture at some point proximate to the first end is greater than the width of the elongate aperture at its middle on the major axis.

In an eighth aspect the invention provides an extrusion process for making an edible skin analogue, the process including the step of: a) introducing into an extruder a mixture including:

(i) pea protein;

(ii) maize grits and/or rice flour;

(iii) pea fibre; b) combining the mixture with water; c) extruding the combined mixture and water through an extruder die, the extruder die having an elongate aperture having a length dimension and a width dimension, wherein the aperture is:

• between about 10 mm and about 20 mm in length, such as about 15 mm in length;

• between about 1 mm and 2 mm in width for the majority of the length of the aperture, such as about 1.5 mm in width for the majority of the length of the aperture; and wherein at each end of the elongate aperture the aperture includes a portion that is between about 2 mm and about 5 mm in width, such as about 3.0 mm in width.

In a ninth aspect the invention provides an edible skin analogue extrusion produced by the extrusion process of the seventh or the eighth aspect.

In a tenth aspect the invention provides an extruder die having an elongate aperture having a major axis and a minor axis, the elongate aperture having a first end and a second end on the major axis, wherein the width parallel to the minor axis of the elongate aperture at some point proximate to the first end is at least 1.1 times (such as at least 1.3 times, such as at least 1.5 times, such as at least 1.7 times, such as at least 1.8 times, such as at least 2 times) greater than the width of the elongate aperture at its middle on the major axis.

In an eleventh aspect the invention provides an extruder die having an elongate aperture having a major axis and a minor axis, the elongate aperture having a first end and a second end on the major axis, wherein the shape of the portions of the aperture at the first end and the second end is substantially circular, the substantially circular shaped portions each having a diameter, and wherein the substantially circular shaped portions are interposed by a substantially rectangular shaped portion of the aperture, wherein the diameter of each substantially circular shaped portions is independently selected from being at least 1.1 times (such as at least 1.3 times, such as at least 1.5 times, such as at least 1.7 times, such as at least 1.8 times, such as at least 2 times) greater than the width of the rectangular shaped portion of the aperture across the minor axis of the aperture.

It has now been found that the texture of pork crackling can be faithfully replicated using plant-based products using the invention described herein. In particular, the combination of: pea protein; maize grits and/or rice flour; and pea fibre, provide a proteinaceous textured product that provides a desirable consumer experience and mouth feel that has not been possible before now.

Further aspects of the invention, which should be considered in all its novel aspects, will become apparent to those skilled in the art upon reading of the following description which provides at least one example of a practical application of the invention.

Brief Description of the Drawings

One or more embodiments of the invention will be described below by way of example only, and without intending to be limiting, with reference to the following drawings, in which:

Figure 1 shows a comparison between the structure of the product of Formulation 1.1 (Figure 1A) and the structure of the product of Formulation 1.2 (Figure IB) resulting from an oven drying method.

Figure 2 shows the structure of the product of Formulation 2.2, resulting from a drying method.

Figure 3 shows an extruder die used in extrusion trial 1.

Figure 4 shows extrudate puffing as it exits the extruder die used in extrusion trial 1.

Figure 5 shows an extruder die used in extrusion trial 2. Figure 6 shows the structure of products formed in extrusion trial 2 - pea protein varying as follows: 0% (top left), 10% (top right), 15% (bottom left) and 20% (bottom right).

Figure 7 shows the structure of products produced as a result of rolling, cutting, and applying Kremelta to the products from extrusion trial 3 formulation including 20% pea protein.

Figure 8 shows the structure of products produced as a result of rolling, cutting, and applying Kremelta to the products from extrusion trial 3 formulation including 20% pea protein.

Figure 9 shows a schematic of the dimensions of the elongate aperture of the extruder die used in extrusion trial 4.

Figure 10 shows a photograph of the extruder die used in extrusion trial 5.

Figure 11 shows a schematic of the side profile (Figure 11A) and the plan view (Figure 11B) of the extruder die used in extrusion trial 5, depicting the location of the stadium shaped tapering portion, the packer, and the depth of the land (10.000 mm).

Figure 12 shows an SEM image of the structure of an edible skin analogue of the invention produced during extrusion trial 5.

Figure 13 shows a Texture Analyser (TA) plot of the force as a function of time for a product from extrusion trial 4.

Figure 14 shows a Texture Analyser (TA) plot of the force as a function of time for a product from extrusion trial 5 showing an enhancement in the fracturability compared with the product from extrusion trial 4.

Figure 15 shows a representation of a typical TA plot and how to calculate numerous parameters therefrom.

Figure 16 shows a schematic in plan and side view of post-processing techniques (rolling and cutting) that can be applied to extrudate exiting an extruder.

Detailed Description of the Invention

Pea Protein Pea protein has gained a lot of interest due to its low allergenicity, high nutritional value, availability and low price associated with it. Pea is rich in protein and carbohydrates and is low in fat. They also contain important vitamins and minerals and a high amount of essential amino acids such as lysine. Pea protein is consisting of mainly two types of proteins, albumins and globulins. Albumins made up around 20% of the total protein in peas. They are considered to be water-soluble proteins and contain a higher concentration of essential amino acids compared to globulins. Albumin protein comprises of enzymes, protease inhibitors, amylase inhibitors and lectins. Albumin can be split into two major fractions, larger albumin protein and a minor one. Large albumin has a molar mass of around 25 kDa comprising of two polypeptides, while the minor albumin protein only has a molecular mass of around 6 kDa. Prolamins and glutenins are also present in pea protein but at a much lower amount.

The globulins proteins are considered to be salt-soluble storage proteins which represent around 70- 80% of total protein. They could be divided into main subgroup legumin and vicilin protein with a small amount of convicilin protein. These storage proteins contain different types of amino acids and are held together by different interactions. Legumin is a hexameric protein with acidic and basic subgroups. The acidic subgroup contains mainly glutamic acid and leucine which are covalently linked by disulfide bonds to the basic subgroup which contains more alanine, valine and leucine. On the other hand, vicilin proteins are trimers that are held together by hydrophobic interactions instead of disulfide bonds. Vicilin contains lower levels of sulfur-containing amino acids (methionine, cystine) and tryptophan and higher levels of acidic (aspartic acid, glutamic acid) and basic (arginine, lysine) amino acids. Lastly, convicilin is the third storage protein in peas which can be found in a smaller amount. Convicilin is also found as trimers with a similar structure to vicilin but they are very different in terms of amino acids profile. Convicilin protein contains higher sulfur-containing amino acids and holds an additional highly charged N-terminal extension. Depending on the method of extraction and extrinsic factors like pH and temperature, the protein structure can be altered.

Pea Protein Extraction

The most common method of pea protein extraction reported in the literature is alkaline extraction. Alkaline extraction utilises the difference between solubility of the legume proteins at different pH. The solubility of pea protein is highest under alkaline conditions and lowest close to their isoelectric point which is between pH 4 and 5. Therefore, alkaline extraction of pea protein is normally followed by isoelectric point precipitation to separate the protein from the solution. To extract the protein, defatted pea with or without the seed coat is dispersed in water. If the peas are not defatted, the protein-lipid interactions would limit the solubility protein solubility and therefore reduce the yield of the isolate. Sodium, potassium or calcium hydroxide is then added to the water to adjust the pH of the water to an alkaline pH. To maximise the protein solubility, the pea is left sitting in the reactor tank for 30-180 minutes. The temperature could also be increased to 50-60 °C to increase the solubility but any higher temperature could lead to protein denaturation. The mixture is then centrifuged, and the supernatant is collected. Hydrochloric acid or sulfuric acid is then added to the supernatant collected to adjust the pH to the isoelectric point to precipitate the protein. The precipitated protein is collected by centrifugation, then washed, neutralised and dried.

The optimal process would give protein isolate yield around 80-94%, with extraction pH being the most important factor that could affect the isolate yield, purity and functionality. The higher alkalinity has been shown to result in a greater yield of isolate, but pH values of 11 and above have shown to be associated with increased starch swelling which leads to starch contamination. Also, while higher temperature and longer standing time are associated with higher isolate yield, the isolate is more susceptible to protein denaturation.

In the present invention, the preferred pea protein used was 80% pea protein powder from Yantai TFull Biotech. Pea protein concentrate (powder) generally contains less protein compared to pea protein isolate which usually has a protein content of around 95%. However, pea protein concentrate is easier for the body to absorb and digest as it has gone through less processing. The extra processing step which further isolates the protein has been shown to destroy nutrients and enzymes, hence, pea protein concentrate is a preferred choice.

In the formulations of the present invention it has been found that a concentration of pea protein of at least 5% w/w of the dry material (non-water), such as at least 10% w/w, such as at least 15% w/w is preferred. In the formulations of the present invention it has been found that a concentration of pea protein of no more than about 40% w/w of the dry material (non-water), such as no more than about 30% w/w, such as no more than about 25% w/w is preferred. In the formulations of the present invention it has been found that a preferred concentration of pea protein is from 5 to 40% w/w of the dry material (non-water) used in the extrusion process, such as from 10 to 30% w/w, such as from 15 to 25% w/w, such as about 20% w/w, such as 20% w/w.

Alternative Proteins In some instances hemp protein may be substituted for pea protein, although the product formed using hemp protein is less crunchy than that formed using pea protein.

Rice Flour

Rice flour is a type of flour which are usually the product of finely milled rice. Different type of rice produces different type of rice flour. Generally, rice flour is made from long or medium grain rice depending on the rice availability in the area of production, but glutinous rice and brown rice can also be used to produce glutinous rice flour and brown rice flour. Rice flour is commonly used as a wheat flour substitute in gluten-free recipes due to its neutral flavour and colour. Rice flour usually contains around 80% starch and 7% protein which is slightly lower than the protein content of wheat flour. Hence, the product made from rice flour would not be able to expand and rise as much due to the lack of gluten protein which would form the internal structure network in the wheat products. On the other hand, rice flour is usually finer compared to wheat flour, this resulted in products made from rice flour will be crispier and brown easier.

In the formulations of the present invention it has been found that a concentration of rice flour of at least 1% w/w of the dry material (non-water), such as at least 5% w/w, such as at least 10% w/w, such as at least 15% w/w is preferred. In the formulations of the present invention it has been found that a concentration of rice flour of no more than about 40% w/w of the dry material (non-water), such as no more than about 30% w/w, such as no more than about 25% w/w is preferred. In the formulations of the present invention it has been found that a preferred concentration of rice flour is from 5 to 40% w/w of the dry material (non-water) used in the extrusion process, such as from 10 to 30% w/w, such as from 15 to 25% w/w, such as about 20% w/w, such as 20% w/w.

Alternative Flour

In some instances chickpea flour may be substituted for rice flour, although this is less preferred since it tends to introduce a bitter flavour.

Maize Grits

Maize Grit, or corn grits, are dried corn kernels which have been ground into a fine, medium, or coarse texture. They are typically bright yellow in colour and in the present invention that colour may not be preferred. That colour can be reduced by using maize grits in combination with pea protein. In the formulations of the present invention it has been found that a concentration of maize grits of at least 1% w/w of the dry material (non-water), such as at least 20% w/w, such as at least 40% w/w, such as at least 50% w/w is preferred. In the formulations of the present invention it has been found that a concentration of maize grits of no more than about 40% w/w of the dry material (non-water), such as no more than about 80% w/w, such as no more than about 60% w/w is preferred. In the formulations of the present invention it has been found that a preferred concentration of maize grits is from 40% to 80% w/w of the dry material (non-water) used in the extrusion process, such as from 50 to 60% w/w, such as from 53 to 58% w/w, such as about 56% w/w, such as 55.7% w/w.

Pea Fibre

Pea fibre is milled from the hull of the whole pea (Pisum Spp.) which is ground to form a fine powder which can be added to a range of food products. With an extremely high fibre content per 100g and a pleasant taste and neutral colour, it can be added to products to help boost the nutritional profile of products with minimal impact on taste and colour.

In the formulations of the present invention it has been found that pea fibre can be used to modulate (such as reduce) expansion volume resultant from extrusion and thus increase the density of the extruded products, leading to harder texture. It has been found that a concentration of pea fibre of at least 1% w/w of the dry material (non-water), such as at least 2% w/w is preferred. In the formulations of the present invention it has been found that a concentration of pea fibre of no more than about 10% w/w of the dry material (non-water), such as no more than about 5% w/w, such as no more than about 4% w/w is preferred. In the formulations of the present invention it has been found that a preferred concentration of pea fibre is from 1% to 5% w/w of the dry material (non-water) used in the extrusion process, such as from 2 to 4% w/w, such as about 3% w/w, such as 3% w/w.

Alternative Fibre

In some instances hemp fibre may be substituted for pea fibre, although the product formed using hemp protein is less crunchy than that formed using pea protein.

Salt

Table salt or sodium chloride (NaCI) is a common ingredient in food manufacturing. It has several functions when it comes to baking and cooking. The main function of salt is to provide flavour for the product. In the formulations of the present invention it has been found that a concentration of salt of at least 0.1% w/w of the dry material (non-water), such as at least 0.2% w/w is preferred. In the formulations of the present invention it has been found that a concentration of salt of no more than about 1% w/w of the dry material (non-water), such as no more than about 0.5% w/w, such as no more than about 0.4% w/w is preferred. In the formulations of the present invention it has been found that a preferred concentration of salt is from 0.1% to 0.5% w/w of the dry material (non-water) used in the extrusion process, such as from 0.2 to 0.4% w/w, such as about 0.3% w/w, such as 0.3% w/w.

The Extruder

The products of the invention are produced using an extrusion process.

As used herein "extruder" takes its standard meaning and typically refers to an instrument designed to use pressure to force a material through an aperture of an element referred to as a die. In that process, typically a fragmented material (such as a particulate material, slurry, etc) is introduced at the end of the extruder opposite to the die, and pressure is exerted on the fragmented material so that it exits the die ideally as a unitary material such as a substantially homogenous continuous mass, having a cross sectional dimension approximating the cross sectional profile of the die. The continuous mass may then be subject to one or more processes such as slicing, chopping, etc to achieve products of desired dimensions.

Preferably the extruder used in the present invention is a twin screw extruder. Examples of preferred extruders are the Clextral EVO32 twin screw extruder, Clextral BC21 twin screw extruder and the Clextral D32 twin screw extruder. The rotation of the two screws will substantially uniformly mix the fragmented material introduced to the extruder and generate pressure and also some heat.

The extruder may be configured to be supplied with additional heat. Such additional heat may be supplied using one or more heating blocks arranged along the length of the extruder in one or more regions. It has been found that the sensorial experience (taste, appearance, and/or texture) of the extruded product is enhanced when a plurality of heating blocks are used wherein the heating block(s) closest to the extruder die is maintained at a high temperature than the heating block furthest from the die. Preferably a series of three of more heating blocks is used to provide a temperature gradient that decreases from the end of the extruder closest to the die to the end of the extruder furthest from the die. Conceptually the heating block may be arranged into a series of functional zones - the first zone facilitates mixing around ambient temperature (for example 10-25 °C); the second zone serves to increase the temperature to less than 100 °C (such as by heating to about 60-90 °C, such as about 80 °C) which also functions to prevent steam backflow and serve as a cold trap; the third zone needs to be at or around 100-110 °C to facilitate water changing from liquid to gas (steam), but not so high as to facilitate excessive starch gelatinisation which can block the die. Generally the heating blocks should remain below 120 °C.

Due to the relatively low moisture content of the extrudate, and higher friction, the screws are typically generating heat through friction.

An example of an arrangement of heating blocks might provide heat along the extruder at 15/80/80/100/110/110 °C respectively, although other temperatures and combinations of temperatures are envisaged. Typically there will be a general trend to provide a temperature gradient that decreases from the end of the extruder closest to the die to the end of the extruder furthest from the die and closest to the powder feed end.

Cutting

It will be understood that there are numerous methods for portioning the extrudate into desirable product sizes, including the use of cutting members (such as a rotating blade) that portion the extrudate at an angle (such as at about 90°) to the longitudinal flow path, and also the use of cutting members (such as blades, wires) that portion the extrudate substantially parallel to the longitudinal flow path. Preferably the extrudate undergoes at least one processing step following exit from the extruder die. Examples of such processes are provided in Figure 16 in both plan view and side view. As shown, extrudate ("crackling") exits the extruder die and may be subject simultaneously to both rolling and (at least partial) cutting so as to supply the extrudate in a convenient form.

Post-extrusion processes

The extrudate of the present invention may be subject to one or more processes following extrusion. In some embodiments the processes may serve to modify the texture and/or ingredient profile and/or nutritional profile of the product.

Fat addition Despite efforts to introduce a higher fat content into the dry mixture that is subject to extrusion, the extrusion process typically led to the fat melting and leaking from the extrudate, as well as impacting on the desired texture.

One or more fats may be added to the extruded product. Examples of fats that might be suitable include: canola and sunflower oil which are two liquid fats at room temperature; coconut oil and cocoa butter which are solid fats at room temperature due to the higher saturated fat content; and margarine (table spread) and Kremelta which are also solid at room temperature as they are hydrogenated fat.

The inventors discovered that the use of a high melting point fat (such as having a melting point above 20 °C such as above room temperature), such as Kremelta (copha), applied after extrusion allowed for the fat content of the extruded product to be increased to a desired level. Kremelta (Copha) is a vegetable shortening made from hydrogenated coconut oil. Due to the high saturated fat content, Kremelta can remain stable in solid form at room temperature up to 36°C. The fat can be applied, such as brushed on the top of the extruded portion. This may also be a good opportunity to add any desired (additional) flavouring to the extruded product.

Baking/Roasting

The product may undergo an additional baking/roasting step.

The baking process may take place at an elevated temperature (above ambient) such as above 90 °C, such as above 100 °C, such as above about 110 °C. Preferably the baking process takes place at a temperature of no more than 160 °C, such as no more than 140 °C. Ideally the baking takes place between 110 °C and 130 °C.

Such a baking process may lead to the loss of a significant proportion, such as most, of the water content of the extruded product.

The product may be baked for sufficient time (such as at least 30 minutes, such as about 45 minutes) to allow the fat to be at least partially incorporated within the product, such as the kremelta melting and being at least partially absorbed into the edible skin analogue.

The product may be baked/roasted for a second time at an elevated temperature to develop roasted notes for sufficient time (such as at least 2 minutes, such as about 5 minutes) to allow the fat to be at least partially incorporated within the product, such as the kremelta melting and being at least partially absorbed into the edible skin analogue.

The roasting process may take place at an elevated temperature (above ambient) such as above 140 °C, such as above 160 °C, such as above about 170 °C. Preferably the roasting process takes place at a temperature of no more than 200 °C, such as no more than 190 °C. Ideally the drying takes place between 175 °C and 185 °C.

Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like, are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense, that is to say, in the sense of "including, but not limited to".

The entire disclosures of all applications, patents and publications cited above and below, if any, are herein incorporated by reference.

Reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that that prior art forms part of the common general knowledge in the field of endeavour in any country in the world.

The invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, in any or all combinations of two or more of said parts, elements or features.

Where in the foregoing description reference has been made to integers or components having known equivalents thereof, those integers are herein incorporated as if individually set forth.

It should be noted that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the invention and without diminishing its attendant advantages. It is therefore intended that such changes and modifications be included within the present invention.

Examples Processing method

Extrusion was proven to provide enhanced product characteristics compared with products produced by oven baking or drying techniques.

Oven Baking

The oven baking method is a common method used to make pork crackling or pork rind in western countries. They are commonly made alongside or as a by-product of roast pork. When baking with roast pork, they are usually baked at lower heat for a longer time to ensure that the meat is cooked. Whereas if it is just the skin, they could be roasted at a higher temperature for a shorter time.

To assess the properties of an edible skin analogue subjected to oven baking, pea protein was dissolved into a mixture with water, oil, starches and other ingredients (Table 1.1) to create a paste that allowed for the product to be spread into a thinner layer. The flattened mixture was then placed into a preheated Fisher & Paykel OB60SCEX1 oven and baked at 200 °C under the grill for 45 minutes. After finishing baking, the products were allowed to cool down before they were assessed.

The product produced from Formulation 1.1 was not preferred, being considered to be overly light and overly brittle to be a preferred pork crackling. The product from Formulation 1.1 could be broken very easily with very little effort. Whereas, if the product was a pork crackling, it would preferably require somewhere between 142 - 387 Newton to break the crackling. Furthermore, the product from Formulation 1.1 also had a lot of fat leaking out which is a common issue that occurs in plant-based products as they lack fibrous structure.

Hence, Formulation 1.2 was developed with rice flour incorporated into the formulation. Wheat flour generally creates a tougher crust due to the higher protein content and the gluten present, but they are often avoided due to gluten being a common allergen. Therefore, rice flour was used in this formulation. The texture created by rice flour may not be as tough compared to wheat flour, but rice flour was believed to provide a more crispy texture on the basis that it might absorb less moisture and fat during cooking. Despite those advantages, it was believed that the product made with rice flour would still struggle to rise due to the lack of structure from gluten. To address that problem, baking powder was added as a leavening agent to help the product rise and form air pockets to mimic the actual pork crackling.

The result from Formulation 1.2 showed a very significant improvement over Formulation 1.1, since the texture of the Formulation 1.2 product was much tougher and required more force to break. As seen in Figure IB, the structure in the product produced by Formulation 1.2 was more distinct compared to Formulation 1.1. The air pockets created by the leavening agent were well maintained in Figure IB. Whereas in Figure 1A, the pocket collapsed shortly after they were removed from the heat. This is due to the addition of baking powder to Formulation 1.2 and it containing rice flour which has the ability to hold the shape as it is getting cooked. Hence, Formulation 1.2 looks more structured and leavened than Formulation 1.1 which gives a more similar texture to an actual pork crackling.

Despite Formulation 1.2 showing great improvement in terms of the texture of the product, less preferably the fat was leaking out of the product after cooking. Thus, a further trial (Trial 2) was conducted to investigate the effect different types of fat have on the amount of fat leaking out after cooking the product. In order to test for this difference, six types of fat were used. They include canola and sunflower oil which are both liquid fats at room temperature, coconut oil and cocoa butter which are solids at room temperature due to the higher saturated fat content, and finally margarine (table spread) and Kremelta which are also solid at room temperature as they are hydrogenated fat. The same amount of each fat was added to a base formula as shown in Table 1.2.

Table 1.2 Increased fat content compositions

The two products made from liquid fat looked almost identical to each other, while the other products made from solid saturated and hydrogenated fat looked somewhat different from each other.

Before the products were baked, each type of fat was mixed with water and pea protein concentrate to create a paste-like structure. Canola and sunflower oil are liquid at room temperature, hence, they both are easily mixed into the paste giving a slightly sticky texture to the paste.

For other fats which are solid at room temperature, they all gave the paste a slightly different texture from each other depending on their properties. Coconut oil, cacao butter, margarine (table spread) and Kremelta are all solid at room temperature but each has different properties and melting points due to differences in the fat content. As seen in Table 1.3, Kremelta contains the highest saturated fat content of 98%, hence it is the most stable at room temperature with the highest melting point. Kremelta has such a high saturated fat content because they are hydrogenated coconut oil, which already contains a very high amount of saturated fat content even before the hydrogenation process. On the other hand, margarine (table spread) not only has a low saturated fat content but has a very low overall fat content. This is due to the majority of the product being made up of water. This low amount of fat resulted in them not having enough fat content to satisfy the FSANZ margarine regulations and thus they are called table spread. But despite the low saturated fat content and the majority of the table spread being water, they still have a high melting and smoking point. This is due to the effects of additives that were added to the products such as emulsifiers (soy lecithin, glycerine, etc).

Table 1.3 Fat content and properties of each fat

From this, the properties of each fat not only affected the properties of the paste but also the final product. Canola and sunflower oil have similar properties and hence the pastes and the final product made from these oils were almost identical. They were easy to mix and after baking, the fats were well contained within the product and would only leak out as they came into contact with something.

Coconut oil, on the other hand, created a more solid paste compared to the two liquid fats but the paste created from coconut oil was more brittle due to the fat being solid. During baking, the coconut oil melted and bubbled due to the low smoke point of the fat. This resulted in a lot of oil leaking out from the final product and also a burning taste as the baking temperature was higher than the smoke point of coconut oil.

Cacao butter was fully solid at room temperature, thus it did not mix well with the protein and water. To combine them into a paste, cacao butter was melted first by application of heat using a microwave, then the melted cacao butter was then mixed with protein and water to create a paste. The paste created by cacao butter was softer than the one made with coconut oil due to the fat being melted before mixing.

However, the texture of the paste was still quite brittle especially after the cacao butter partially cooled and started to re-solidify. The final product produced by cacao butter was also shown to have a lot of fat leaking out similar to the one made with coconut oil but since the smoke point of cacao butter is much higher than coconut oil, the product produced by cacao butter did not have the burnt taste that was present in coconut oil product.

Kremelta was another solid fat used which did not mix well with protein and water due to the high saturated fat content causing the fat to be too solid at room temperature. The fat was melted first using a microwave before being mixed with water and protein. The melted Kremelta combined well with the rest of the ingredients creating a very soft paste that can be easily spread. Furthermore, once the paste made with Kremelta was spread and allowed to sit, the fat resolidified very quickly resulting in almost a solid-like structure. The final result of the product made using Kremelta was found to be quite surprising. Bubbling and melting of Kremelta could be observed while the product was in the oven but upon removing it from the oven and letting it cool down, fat leaking was no longer observed as the fat tends to resolidify quite quickly. Finally, margarine (or table spread) was used to make a paste, which was significantly softer than any other. This is due to the high water and lower fat content compared to other types of fat. The colour of the paste and final product from margarine is more yellow than the others, this is most likely due to the additive colour added in the process of making margarine. The final product that used margarine also has very little oil leaking out, which could be due to the emulsifiers present in the fat. However, the product made from margarine is not as crispy and tough as products made from other fats and tends to form a mushy texture due to the high water content.

While at least some of the products produced in this example using oven baking were edible and had a texture and composition of, or approaching, the desired parameters, further studies were commenced using alternative processing techniques.

Drying

Drying was another method that was investigated as it was thought to have the potential to be a good method for making plant-based pork crackling snacks based. Instead of cooking the pea protein mixture in the oven, this drying method allows the protein to be cooked first before placing them into the oven.

To produce a plant-based pork crackling using the drying method, pea protein, water, oil, starches and other ingredients were mixed and heated in a pot. The mixture is heated under medium heat for around 15-20 minutes. Once cooked, the mixture is transferred to a baking tray and flattened. The flattened mix was then placed into a Fisher & Paykel OB60SCEX1 oven and baked at 95°C until the mix is dried and crispy, the drying takes around 3 hours but may vary depending on the thickness of the pea protein mixture.

Textured Vegetable Protein is generally made with soy protein and produces a stronger (larger tensile strength) and more fibrous structure than pea protein (Floor et al., 2019). Unfortunately, soy protein is a common allergen and would ideally be avoided in creating a generally tolerated edible skin analogue.

Pea protein concentrate was mixed into a solution with water and oil. Once mixed, the mixture was heated over medium heat for roughly 20 minutes until the proteins were cooked. As the mixes were getting cooked, an increase in the viscosity of the mix could be easily noticed. Especially with the addition of rice flour in Formulation 2.2, the mix formed a sticky elastic paste compared to the softer and frailer paste produced by Formulation 2.1. The mixes were then transferred to a baking tray where they are flattened to around 2 mm thick and cut into pork crackling shape and size. The mix was then dried in the oven at 95 °C for 3 hours or until the product was completely dried.

Table 2.1: Formulations for drying trial

As seen in Table 2.1, assuming that all the moisture got removed during drying, around two-thirds of Formulation 2.1 was pea protein and the rest was sunflower oil. Whereas in Formulation 2.2, rice flour was added to the formulation to improve the flavour and texture which resulted in slightly lower protein content.

The product produced using Formulation 2.1 showed great texture in terms of hardness where the hardness was somewhat similar to an actual pork crackling. However, upon consuming the product, the taste of the pea protein was not ideal, and the product tends to be flaky and leave a grainy feeling in the mouth. Thus, rice flour was incorporated into the formulation to improve the flavour. In Formulation 2.2 (Figure 2), the product showed a similar hardness to Formulation 2.1 product but without any flakes or grainy feeling. Therefore, Formulation 2.2 was preferred and more closely resembled the functional properties of actual pork crackling.

Extrusion

Extrusion was also investigated as a means of processing the composition. Low moisture extrusion, usually with a moisture content below 20% was initially targeted to provide an internal structure to give pork crackling the distinct crunch.

To extrude the product, a Clextral BC21 twin-screw extruder machine was used.

Extrusion Trial 1 - one inch slit die

The pea protein powder was mixed with other dry ingredients to create a dry mix according to the formulations provided in Table 3.1.

Table 3.1 Formulations for Extrusion trial 1

The individual dry mixes were then separately added to the extruder where it was mixed with water and extruded out at a relatively high temperature and pressure.

In particular, to start extruding the dry mix was added to the extruder through the feed hopper at a feed rate of around 8 kg/hr and the water feed rate was adjusted until the desired water content was achieved (around 15-20%).

In this trial, the extruder die (2) used included a slit (4) as shown in Figure 3 - the slit having approximate dimensions of 2.5 cm (one inch) by 2.5 mm. The extruder screws were set to rotate at 250 rpm with the extruder barrel set at the temperature gradient: ambient/50/80/90/100/100/110 °C. The extruded products were then dried in the INOXTREND XBP-120E oven at 70 °C for 30 minutes to remove substantially all of the excess moisture.

As the dry mix is fed into the extruder through the feed hopper, it enters into the extruder barrel where the rotating screws compress the material so that it is exposed to relatively high shear, temperature and pressure. During this process, the dry mix was converted from a solid into a liquid mix. The relatively high temperature and pressure in the extruder barrel causes the protein to substantially denature and starch to substantially gelatinise which initiates the formation of texture and structure. As the material moves further along the barrel, it reaches the die exit where the pressure and temperature difference causes the product to expand and create a puffed product (6) as it leaves the extruder die (2) as shown in Figure 4.

The colour of the products produced from the formulae in Table 3.1 was bright yellow primarily due to the inclusion of corn grits, and the inventors considered that this did not faithfully replicate the appearance of a pork crackling product and was not ideal. Upon adding more pea protein to the formulation, the product was browner which is closer to the appearance of an actual pork crackling and was determined to be more preferred. While the product was still edible, it was believed that the products produced from this trial were too large and were tougher than was ideal, which was believed to be the result of the dimensions of the aperture of the die and the extruded temperature and screw speed not being high enough. The one-inch die not only affected the size of the product produced but also affected the texture of the product. The inventors considered that the larger die resulted in less pressure difference between the die and the atmosphere upon egress from the extruder die and thus the expansion ratio was lower than was desired when this larger die was used. The extruder conditions such as the screw speed and the barrel temperature were also believed to have a significant effect on the texture and hardness of the product. In this case, both the screw speed and the barrel temperature were low, resulting in a less expanded and tougher product.

Extrusion trial 2 - 15 mm slit

This trial was carried out with improvements based on extrusion trial 1. It was believed that in extrusion trial 1 the screw speed and extruded temperature were not high enough, so in this trial 2, the screw speed was increased to 350 rpm and the extruder barrel temperature was set to ambient/50/80/90/100/110/120 °C. The formulation was also improved from extruder trial 1 - coarse rice flour was substituted in the formulation for some of the maize grits to give the product a more neutral colour rather than yellow as represented in Table 3.2. Pea fibre was also added to the product to reduce expansion volumes and increase the density of extruded products, so as to provide a harder texture.

Table 3.2 Formulations for Extrusion trial 2

The extruder die was also changed from a one-inch slit die to a smaller slit die (8) as seen in Figure 5. As depicted, the extruder die has an elongate aperture having a major axis and a minor axis, the elongate aperture having a first end and a second end on the major axis, wherein the width parallel to the minor axis of the elongate aperture at some point proximate to the first end is greater than the width of the elongate aperture at its middle on the major axis. In this case the extruder die has an elongate aperture having a length dimension and a width dimension, wherein the aperture is:

• about 15 mm in length;

• about 1.5 mm in width for the majority of the length of the aperture; and wherein at each end of the elongate aperture the aperture includes a portion that is about 3.0 mm in width. In particular, the portion that is about 3.0 mm in width is a substantially circular portion having a diameter of about 3.0 mm. In some embodiments, the shape of the aperture could be described as being dumb-bell shaped; dog-bone shaped; or bola shaped.

The extruded product so produced was much smaller in size compared to the ones from Extrusion trial 1 due to the smaller dial used. The colour of the product in this trial differs as the pea protein concentration changes as pea protein tends to give the product more of a brown colour. Thus, formulations with less pea protein tend to be more yellow whereas formulations with more pea protein have a darker shade of brown. Furthermore, as seen in Figure 6 (Pea protein varying as follows: 0% (top left), 10% (top right), 15% (bottom left) and 20% (bottom right)), as more pea protein has been incorporated into the product, the product tends to have finer air bubbles and less expansion. So, increasing the protein and fibre content in the product resulted in a decrease in expansion ratio but despite the finer air bubbles and less expansion, the difference in texture is not noticeable.

From the extrusion trial it was concluded that products made from the formulation with 20% pea protein had the most uniform shape which is the most suitable for a pork crackling snack product. Since they also contained the highest protein content out of all the extruded products, they were ideal candidates to be used for further development of plant-based pork crackling.

Extrusion trial 3 - optimised formulation

The following formulation was determined to provide the optimised flavour, texture, colour and nutritional composition when extruded (Table 3.3):

Table 3.3 Optimised formulation

Post processing of extruded products

In order to further improve the flavour and texture of the product, the extruded product was placed in the oven to grill for around 10 minutes to make it crispier. A mix of Kremelta and flavouring (such as liquid smoke) was brushed onto the product to add some fattiness to it as fattiness is the main aspect missing from the extruded products compared with an actual pork crackling. Since there is a limitation for the amount of fat that could be added to an edible skin analogue, it was decided that the fat would be incorporated into the product after being extruded. The Kremelta was preferred since the Kremelta fat tends to solidify quite quickly after cooking, and hence the fat doesn't leak out that much since it is hydrogenated coconut oil. The products produced as a result of the post-processing of the extrusion trial 2 formulation including 20% pea protein is shown in Figure 7 (cross section showing the internal structure) and Figure 8 (edible skin analogues that closely resemble pork crackling).

These post processing methods have been generally applied to the products of Extrusion Trial 4 and 5.

Extrusion Trial 4 - Die optimisation

Further optimisation work was conducted on the extruder die. The extruder die was changed to have a smaller length slit as shown schematically in Figure 9. As depicted, the extruder die has an elongate aperture (10) having a major axis (substantially lengthwise) and a minor axis (substantially widthwise), the elongate aperture having a first end (12) and a second end (14) on the major axis, wherein the width parallel to the minor axis of the elongate aperture at some point proximate to the first end is greater than the width of the elongate aperture at its middle on the major axis. In this case the extruder die has an elongate aperture having a length dimension and a width dimension, wherein the aperture is:

• about 10 mm in length;

• about 1.5 mm in width for the majority of the length of the aperture; and wherein at each end of the elongate aperture the aperture includes a portion that is about 3.0 mm in width. In particular, the portion that is about 3.0 mm in width is a substantially circular portion having a diameter of about 3.0 mm. In some embodiments, the shape of the aperture could be described as being dumb-bell shaped; dog-bone shaped; or bola shaped. Extrusion Trial 5 - Die optimisation

Further optimisation work was conducted on the extruder die. The extruder die was changed to have two substantially identical elongate apertures as seen in Figure 10.

Without wishing to be bound by theory, it is believed that using two elongate slits that are disposed so that their major axes are substantially horizontal is advantageous commercially compared with the use of a die having only one elongate slit since it allows for the simultaneous production of two ribbons effectively doubling production output. Those two ribbons remain separate by virtue of the side-by-side relationship of the slits.

In this embodiment, the extruder die has an elongate aperture having a major axis and a minor axis, the elongate aperture having a first end and a second end on the major axis, wherein the width parallel to the minor axis of the elongate aperture at some point proximate to the first end is greater than the width of the elongate aperture at its middle on the major axis. In this case the extruder die has an elongate aperture having a length dimension and a width dimension, wherein the aperture is:

• about 15 mm in length;

• about 1.5 mm in width for the majority of the length of the aperture; and wherein at each end of the elongate aperture the aperture includes a portion that is about 3.0 mm in width. In particular, the portion that is about 3.0 mm in width is a substantially circular portion having a diameter of about 3.0 mm. In some embodiments, the shape of the aperture could be described as being dumb-bell shaped; dog-bone shaped; or bola shaped.

Furthermore, it has been discovered by the inventors that the land of the die has an impact on the properties of the extruded product. In the field of extrusion technologies, the "land" of the extrusion die is the portion of the die through which the extruded material passes and which contains substantially straight edges along the direction of travel of the extruded material. The land length is the length of the straight section within the die. The inventors have discovered that the land length is optimally about 10 mm, and this results in optimised expansion of the material upon exit from the extruder die. The land of the die used in extrusion trial 4 was 5 mm and the product was not as good as the product from extrusion trial 5.

In addition, it has been discovered that the die may also include a tapering region (also referred to as a funnel region) so that material to be extruded is forced through a region of decreasing overall cross- sectional proportions prior to being extruded through the land of the die. As shown in Figure 10 and in Figure 11, the die of extrusion trial 5 includes a stadium-shaped (also called a discorectangle, obround, or sausage body) tapering region from the internal face of the extruder die to the face that includes two elongate apertures. The edges of the various intersecting shapes/planes may be preferably chamfered to include a curved edge of a small radius.

The die may also include a packer of approximately 2 mm as shown in Figure 11.

Water inclusion optimisation

Water (or additional water) may be added directly into the barrel of the extruder after the mixture to be extruded has been added. The water may comprise between 2 and 20% (w/w) of the total weight of the extruded product; such as between 4% (w/w) and 10% (w/w); such as approximately 6% (w/w).

Characterisation of extruded products

In order to assist with quality control, a range of techniques were adopted to help characterise and quantify the properties of the edible skin analogues of the invention.

Pore structure

Scanning Electron Microscopy (SEM) was used to qualitatively and quantitatively identify properties of the desired products of the invention. An SEM scans a focused stream of electrons over a surface to create an image. The electrons in the beam interact with the sample, thereby producing various signals that can be used to obtain information about the surface's topography and composition. As the food samples are poorly conducting specimens, the sputter coated electrically conducting metal, gold can help with the viewing and imaging under the SEM. Sputter coating prevents charging of the specimen, which would otherwise occur because of the accumulation of static electric fields. It also increases the amount of secondary electrons that can be detected from the surface of the specimen in the SEM and therefore increases the signal to noise ratio. SEM Model: Hitachi tabletop SEM model - TM3030Plus at an accelerating voltage of 15 kV. Sample preparation: the samples were sputter coated with gold at 100 angstrom thickness. As shown in Figure 12, the pores are irregularly shaped and sized, and the pore sizes may generally range from 0.6 to 1.2 mm. The thickness of the cell/void walls may be generally of the order of 0.052-0.084 mm.

Texture Crispness is the key trait of cellular, brittle and crunchy food. The crispness of a deep-fried pork rind is very different from French fries, corn chips like snacks.

In this experiment, we used texture analyser (TA. XT Plus) to compare the texture profile of a plantbased pork crackling and a corn chips like snack. Texture Profile Analysis is a popular double compression test for determining the textural properties of foods. It is occasionally used in other industries, such as pharmaceuticals, gels, and personal care. During a TPA test samples are compressed twice using a texture analyzer to provide insight into how samples behave when chewed. The TPA test was often called the "two bite test" because the texture analyzer mimics the mouth's biting action. Characteristics that can be used to qualitatively or quantiatively assess a materials physical properties, as they relate to consumption, include:

Hardness is the force required to bite through the sample using the molars (low force/ soft to high force/ hard).

Force to grind the force required to break through the sample by grinding the teeth after biting/chewing through to the skin or fibre (non to large amount).

Fracturability the force with which the sample ruptures when placing the sample between the molars and biting down at an even rate (crumbles to fractures).

Crispness the force with which a product breaks or fractures (rather than deforms) when the product is chewed with the molar teeth characterised by many small breaks (not crisp to very crisp).

Crunchiness the force with which a product breaks or fractures (rather than deforms) when a product is chewed with the molar teeth, characterised by few, large breaks (not crunchy to very crunchy)

Cohesiveness the amount the sample deforms rather than crumbles, cracks, or breaks (ruptures to deforms)

Denseness the compactness of the cross section of the sample while biting completely through with the molars (airy to dense/ compact) Flinty The degree to which the product shards into sharp slivers during the bite down similar to a hard peppermint stick candy.

A Texture Analyser methodology was also used to qualitatively and quantitatively identify properties of the desired products of the invention using the formulation from extrusion trial 4 and from extrusion trial 5.

Hardness and crispness were analyzed with a Texture analyzer TA-XT2i (Stable Micro Systems, UK), using a 3-mm diameter lance probe. The samples were compressed 25% at a speed of 1.0 mm/s. Compatible software for the texture analyzer made it possible to determine the hardness and crispness of the samples at the same time during compression. The graph generated revealed peaks when the probe pierced the samples. Every peak represented the resistance force to the probe by the measured sample. The highest peak was interpreted as the hardness of the product, expressed in Newtons (N). Crispness was interpreted as the total peak count. The analysis was run in triplicate, analysing a single rind at a time (n=10) from each pack.

The texture profile of pork crackling was also analysed by texture analyser (TAXT Plus, Stable Microsystems, Surrey, UK). The samples were cut into 10 mm ³ and the texture profile, i.e., hardness and crispiness of the samples was analysed. Each sample was compressed by a flat platen of 5 mm diameter. The crosshead speed was 20 mm/min and maximum extent of deformation 60% of the original height.

The hardness of the samples is defined as the maximum force of the first peak (Figure 15).

While the cohesiveness is defined as the area of the second compression divided by the area of the first compression, and the springiness is defined as the distance of the detected height during the second compression divided by the original compression distance (Figure 15). The chewiness is the factor of hardness, cohesiveness, and springiness (Figure 15). Texture profile analysis (TPA) was performed as a series of replicates. The results from the texture analysis are summarised in Table 4.1.

Table 4.1 Figure 13 shows that the products from extrusion trial 4 provided fewer total peaks during the first compression, whereas the product from extrusion trial 5 provided a substantial number of fracturing peaks during the first compression. These results quantitatively confirm that extrusion trial 5 produced product that had strong crack fracturability but which is subsequently not overly hard when compared with the product from extrusion trial 4. Advantageously, the product from extrusion trial 5 most closely mimics pork crackling - providing the ideal structure as a honeycomb and best customer experience / mouth feel when trialling the product.

In this case, the texture of a series of replicate products from extrusion trial 4 (data shown in Figure 13) was compared with the texture of a series of replicate products from extrusion trial 5 (data shown in Figure 14). The texture analysis confirms that the texture of the product from extrusion trial 5 had pronounced fracturability prior to the peak hardness level. That texture is desirable and indicative of a faithful replication of the texture of pork crackling. Preferably the products of the invention will be characterised as having a fracturability of at least 40% of the hardness of the sample, such as at least 50% of the hardness of the sample, such as at least 60% of the hardness of the sample, such as at least 70% of the hardness of the sample, such as at least 75% of the hardness of the sample.