Food Products This application claims priority from Australian Provisional Patent Application No. 2021902751 filed on 25 August 2021, the contents of which are to be taken as incorporated herein by this reference. Technical Field The present invention relates to food products and processes for their preparation. More particularly, the present invention relates to plant-based meat analogue food products and processes for their preparation. Background of Invention Plant-based diets are increasingly being pursued by consumers as the global demand for sustainable diets is growing. The role which animal products play in global warming and other environmental impacts has led to an increased interest in plant-based substitutes to traditional meat and dairy products. For example, meat analogues (also known as plant-based meat, vegan meat, meat substitutes, meat mimetics, mock meat, meat alternatives, imitation meat, or vegetarian meat) are meat-like substances made from vegetarian ingredients. Many consumers are keen to reproduce the experience of cooking and eating meat so there is a desire for meat analogues which approximate the aesthetic qualities (such as texture, flavour and appearance) and/or chemical characteristics of different types of meat. Haemoglobin and myoglobin are sarcoplasmic oxygen-binding proteins which are predominantly responsible for the red colour of blood and meat, respectively. Depending on the redox state of heme iron and the ligand on the sixth coordination site within the myoglobin molecule, meat will appear purple/red (deoxymyoglobin, Fe ²⁺ , no ligand), bright red (oxymyoglobin, Fe ²⁺ , O ₂ ) or brown (metmyoglobin, Fe ³⁺ , H ₂ O). In red meat, upon cooking, myoglobin is oxidised to metmyoglobin, thus a typical visual colour change from red to brown occurs. In the case of meat from species with low intrinsic myoglobin concentrations, e.g., chicken, this colour change appears visually as pink to white due to protein coagulation. This colour change provides a visual indicator, aiding to guide cooking time required to achieve the desired flavour and/or texture of the cooked product. It also provides an indicator to the consumer that meat maybe under- or over-cooked. While meat analogues have sought to mimic the red colour of raw meat, there are few successful analogues for the colour change provided by the cooking of haemoglobin and myoglobin. For example, many meat analogue products use colouring from beetroot, burnt sugar, or black cacao extract to provide a desired colour. These products do not, however, change colour upon normal cooking temperatures. One previously described example of a plant-based meat analogue product uses a recombinant form of haemoglobin derived from soy to provide colour to the product and a colour change process during cooking. Such examples, however, are rare. There is therefore an ongoing need for improved plant-based substitutes to traditional meat and dairy products, which at least partially addresses one or more of the above-mentioned shortcomings, or provides a useful alternative. Particularly, there is an ongoing need for improved meat analogue products, which at least partially addresses one or more of the above-mentioned shortcomings, or provides a useful alternative. A reference herein to a patent document or other matter which is given as prior art is not to be taken as an admission that the document or matter was known or that the information it contains was part of the common general knowledge as at the priority date of any of the claims. Summary of Invention In a first aspect the invention provides the use of at least one colour-change protein for preparing a food product, wherein the colour-change protein imparts a colour to the food product and loses or changes said colour on cooking. In a further aspect the invention provides a food product comprising at least one colour-change protein, wherein the colour-change protein imparts a colour to the food product and loses or changes said colour on cooking. In a further aspect the invention provides a method of preparing a food product comprising the step of including at least one colour-change protein in the food product, wherein the colour-change protein imparts a colour to the food product and loses or changes said colour on cooking. Further aspects of the invention appear below in the detailed description of the invention. Brief Description of Drawings Embodiments of the invention will herein be illustrated by way of example only with reference to the accompanying drawings in which: Figure 1 is an absorbance spectrum of AmilCP-Pink at different protein concentrations. Figure 2 is a set of absorbance spectra showing the absorbance at 490, 524 and 558 nm of AmilCP-Pink at different protein concentrations during heating. Figure 3 is an absorbance spectrum of Spis-pink at different protein concentrations. Figure 4 is a set of absorbance spectra showing the absorbance at 490, 524 and 564 nm of Spis-pink at different protein concentrations during heating. Figure 5 is a plot showing the derivative calculation of the thermal denaturation temperature (Tm) of Spis-Pink at varying protein concentration at 564 nm. A linear model was fitted to the data (solid line) with the standard error shown around the fit line as the shaded area. Figure 6 is an absorbance spectrum of PaxPink at different protein concentrations. Figure 7 is a set of absorbance spectra showing the absorbance at 480, 515 and 550 nm of PaxPink at different protein concentrations during heating. Detailed Description Before describing the present invention in detail, it is to be understood that the terminology used herein is for the purpose of describing embodiments only and is not intended to be limiting. Unless specifically defined otherwise, all technical and scientific terms used herein shall be taken to have the same meaning as commonly understood by one of ordinary skill in the art. As used in this specification and the appended claims, the singular forms “a”, “an” and “the” include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to a “a colour change protein” includes a combination of two or more such proteins. Throughout the description and claims of the specification the word “comprise” and variations of the word, such as “comprising” and “comprises”, is not intended to exclude other additives, components, integers or steps. As used herein, “comprises” means “includes”. Thus, “comprising A or B,” means “including A, B, or A and B,” without excluding additional elements. The term "and/or" as used herein is to be taken as specific disclosure of each of the two specified features or components with or without the other. For example "A and/or B" is to be taken as specific disclosure of each of (i) A, (ii) B and (iii) A and B, just as if each is set out individually herein. As used herein, the term “a food product” refers to a substance that can be used or prepared for use as food, which is any nutritious substance that humans or animals (preferably mammals) eat or drink in order to maintain life and growth. As used herein, the term “meat analogue food product” refers to a food product that approximates the aesthetic qualities, nutritional and/or chemical characteristics of animal- sourced meat such as texture, flavour, mouthfeel, appearance, structure, and composition. A skilled person will appreciate that meat analogue food products are generally plant-based. In some embodiments of the present invention, meat analogue food products contain substantially no ingredients from animal sources; while in other embodiments, however, meat analogue food products may contain ingredients from animal sources where required. In some embodiments of the present invention, the food product comprises texturised vegetable protein, preferably from soy. It will be understood that the colour-change protein for use in the present imparts a colour to the food product, meaning that it alters the colour of the food product. Upon cooking at a desired colour-change temperature, the colour-change protein changes colour, likely due to the protein denaturing, meaning that the food product also changes colour. In one embodiment, the present invention relates to the use of at least one colour- change protein for preparing a food product, wherein the colour-change protein imparts a colour to the food product and changes said colour on cooking. In another embodiment, the present invention relates to a food product comprising at least one colour-change protein, wherein the colour-change protein imparts a colour to the food product and changes said colour on cooking. In a further embodiment, the present invention relates to a method of preparing a food product comprising the step of including at least one colour-change protein, wherein the colour-change protein imparts a colour to the food product and changes said colour on cooking. As used herein the term “cooking” refers to various methods of using heat to prepare food for consumption and includes all cooking techniques such as frying, steaming, grilling, baking, roasting, boiling and smoking. It will be understood that the colour-loss or colour-change temperature of the colour-change protein can be modified by several factors such as the structure of the protein and the cooking environment. Preferably, the colour-loss or colour-change temperature of the food product is greater than around 50 ºC, more preferably between around 50-85 ºC. In a preferred embodiment, the colour-change temperature of the food product is greater than around 50 ºC. In some embodiments, the colour-change temperature of the food product is around 60 ºC. In some embodiments, the colour-change temperature of the food product is around 70 ºC. In some embodiments, the colour-change temperature of the food product is around 80 ºC. In some embodiments, the colour-change temperature of the food product is around 90 ºC. In some embodiments, the colour-change temperature of the food product is around 100 ºC. In some embodiments, the colour-change temperature of the food product is between around 50-100 ºC. In some embodiments, the colour-change temperature of the food product is between around 50-90 ºC. In some embodiments, the colour-change temperature of the food product is between around 50-80 ºC. In some preferred embodiments, the colour-change temperature of the food product is between around 50-85 ºC. Preferably, the colour-change protein changes colour on cooking the food product at a temperature of greater than around 50 ºC, more preferably between around 50-85 ºC. In a preferred embodiment, the colour-change protein changes colour on cooking the food product at a temperature of greater than around 50 ºC. In some embodiments, the colour- change protein changes colour on cooking the food product at a temperature of greater than around 60 ºC. In some embodiments, the colour-change protein changes colour on cooking the food product at a temperature of greater than around 70 ºC. In some embodiments, the colour-change protein changes colour on cooking the food product at a temperature of greater than around 80 ºC. In some embodiments, the colour-change protein changes colour on cooking the food product at a temperature of greater than around 90 ºC. In some embodiments, the colour-change protein changes colour on cooking the food product at a temperature of greater than around 100 ºC. In some embodiments, the colour-change protein changes colour on cooking the food product at a temperature of between around 50-100 ºC. In some embodiments, the colour-change protein changes colour on cooking the food product at a temperature of between around 50-90 ºC. In some embodiments, the colour-change protein changes colour on cooking the food product at a temperature of between around 50- 80 ºC. In some preferred embodiments, the colour-change protein changes colour on cooking the food product at a temperature of between around 50-85 ºC. The skilled person will appreciate that the present invention is applicable to a range of different food products where it is desirable to impart a colour change upon cooking. In some preferred embodiments, the food product is a meat analogue food product. In these embodiments, preferably, the colour that the colour-change protein imparts to the food product is a pink/red colour. In other embodiments, the food product may be, for example, a dairy substitute or a beverage and the preferred colour is one that mimics the analogous animal-sourced product. As used herein, the term “colour-change protein” refers to proteins from the protein family of green fluorescent protein (GFP)-like proteins and related fluorescent proteins (FP) and non-fluorescent chromoproteins (CP) that all share a homologous β-barrel tertiary structure (known as a “β-can” type structure) made up of an 11-stranded β-barrel with an α- helix running through the β-barrel. It will be appreciated that the colour change is observable in the visible light spectrum, that is from about 380 nm to about 750 nm. For the purposes of the present invention, “colour-change protein” does not encompass haemoglobin and myoglobin, the proteins in meat that impart a pink/red colour that is lost upon cooking. Green fluorescent protein (GFP)-like proteins are a family of proteins from marine species that all share the “β-can” type structure comprising a homologous β-barrel tertiary structure made up of an 11-stranded β-barrel with an α-helix running through the β-barrel. GFP-like proteins are either fluorescent proteins (FP) or non-fluorescent chromoproteins (CP). The light absorption and emission characteristics of these proteins span most of the visible spectrum. From emission properties, these groupings generally comprise fluorescent proteins with cyan, green, yellow and red emission, whilst the chromoproteins intensely absorb visible light to give strong colours in ambient light, ranging from blue to red to purple (and all colours in between) in colour. The chromophore is located in the centre of the barrel and is protected from bulk solvent by lids composed of short helices. The chromophore is encoded by the primary amino acid sequence and results from the autocatalytic post-translational modification of the conserved -X-Tyr-Gly- tripeptide, where X represents any amino acid, without any co-factor or substrate involved. Even though GFP-like proteins are derived from completely unrelated species and can have very little primary amino acid sequence homology, they exhibit very little variation in the tertiary protein structure. The quaternary structure of the protein depends on the individual protein but is either a monomer, homodimer or homotetramer. The skilled person will appreciate that colour-change proteins suitable for use with the present invention are selected from the protein family of green fluorescent protein (GFP)- like proteins and/or from proteins having a “β-can” type structure. In a preferred embodiment of the present invention, the colour-change protein is selected from the protein family of green fluorescent protein (GFP)-like proteins. In another preferred embodiment, the colour-change protein has a “β-can” type structure. It will be appreciated that colour-change proteins suitable for use with the present invention are fluorescent proteins (FP) or chromoproteins (CP) which have a colour change which is observable in the visible light spectrum, that is from about 380 nm to about 750 nm. In some preferred embodiments, the colour-change protein is a fluorescent protein (FP) or chromoprotein (CP) with a maximum fluorescence emission wavelength at 450-700 nm, preferably 500-600 nm. In other preferred embodiments, the colour-change protein is a fluorescent protein (FP) or chromoprotein (CP) with a maximum absorption wavelength at 450-700 nm, preferably 480-600. In some embodiments of the present invention, the colour-change protein is a green fluorescent protein (GFP)-like protein that has been genetically modified to enhance properties suitable for use with the present invention, such as colour, colour change or to modify the colour loss temperature. Examples of colour-change protein that are suitable for use with the present invention include amilCFP, anobCFP1, anobCFP2, meffCEP, mmilCFP, meleCFP, efasCFP, psamCFP, aacuGFP1, aacuGFP2, aeurGFP, afraGFP, amilGFP, anobGFP, eechGFP1, eechGFP2, eechGFP3, efasGFP, fabdGFP, gfasGFP, meffGFP, plamGFP, pporGFP, sarcGFP, stylGFP, amilRFP, meffRFP, pporRFP, eechRFP, meleRFP, scubRFP, eforCP/RFP, aacuCP, ahyaCP, amilCP, gfasCP, gdjiCP, meffCP, stylCP, spisCP, CP-560, CP-562, mOrange, tdTomato, mTangerine, mStrawberry, mCherry, scOrange, eforRed, asPink(asCP), meffRed, tsPurple, spisPink, amilCP_Pink, PaxPink, and combinations thereof. Preferably, the colour-change protein is selected from the list consisting of amilRFP, meffRFP, pporRFP, eechRFP, meleRFP, scubRFP, eforCP/RFP, aacuCP, ahyaCP, amilCP, gfasCP, gdjiCP, meffCP, stylCP, spisCP, CP-560, CP-562, mOrange, tdTomato, mTangerine, mStrawberry, mCherry, scOrange, eforRed, asPink(asCP), meffRed, tsPurple, spisPink, amilCP_Pink, PaxPink, and combinations thereof. More preferably, the colour-change protein is chromoprotein spisPink, from the coral Stylophora pistillata. More preferably, the colour- change protein is chromoprotein amilCP_Pink. More preferably, the colour-change protein is chromoprotein PaxPink. In a preferred embodiment, the colour-change protein suitable for use with the present invention comprises the following amino acid sequence, mOrange (fluorescent): In a preferred embodiment, the colour-change protein suitable for use with the present invention comprises the following amino acid sequence, tdTomato (fluorescent): In a preferred embodiment, the colour-change protein suitable for use with the present invention comprises the following amino acid sequence, mTangerine (fluorescent): In a preferred embodiment, the colour-change protein suitable for use with the present invention comprises the following amino acid sequence, mStrawberry (fluorescent): In a preferred embodiment, the colour-change protein suitable for use with the present invention comprises the following amino acid sequence, mCherry (fluorescent): In a preferred embodiment, the colour-change protein suitable for use with the present invention comprises the following amino acid sequence, eforRed(CP) (fluorescent): In a preferred embodiment, the colour-change protein suitable for use with the present invention comprises the following amino acid sequence, asCP562 (asulCP562) (fluorescent): In a preferred embodiment, the colour-change protein suitable for use with the present invention comprises the following amino acid sequence, meffRed(RFP) (fluorescent): In a preferred embodiment, the colour-change protein suitable for use with the present invention comprises the following amino acid sequence, amilCP_Pink (fluorescent): In a further preferred embodiment, the colour-change protein suitable for use with the present invention comprises the following amino acid sequence, spisPink(spisCP) (non- fluorescent): In a further preferred embodiment, the colour-change protein suitable for use with the present invention comprises the following amino acid sequence, PaxPink (non- fluorescent): In a further embodiment, the colour-change protein suitable for use with the present invention will impart a colour to a food product and changes said colour on cooking, and wherein the colour-change protein has at least 80% sequence identity, preferably at least about 85% sequence identity, more preferably at least about 90% sequence identity, most preferably at least about 95% sequence identity to the one of the following amino acid sequences: mOrange (fluorescent): tdTomato (fluorescent): mTangerine (fluorescent): mStrawberry (fluorescent): mCherry (fluorescent): eforRed(CP) (fluorescent): asCP562 (asulCP562) (fluorescent): meffRed(RFP) (fluorescent): amilCP_Pink (fluorescent): spisPink(spisCP) (non-fluorescent): PaxPink (non-fluorescent): Examples The invention will now be further explained and illustrated by reference to the following non-limiting examples. Chromoprotein molecular biology and small-scale screening Table 1 Chromoproteins overview The genes for the proteins in Table 1 were codon optimised for E. coli, synthesized and cloned into the pET-28a(+) plasmid using the Ndel/Xhol cloning site by the commercial company GenScript®. The lyophilized plasmid was resuspended in Milli-Q water and transformed into competent E. coli T7 Express lysY using the heat shock method. The transformed E. coli were then streaked on LB agar containing 50 μg/mL kanamycin and grown for 24 h at 37 °C to select for strains containing the plasmid of interest. Five individual colonies for each strain were then selected and grown in 10 mL LB broth containing 50 μg/mL kanamycin for 6 h at 37 °C before induction with 1 mM IPTG overnight.1mL cells were harvested by centrifugation and the cell pellets investigated for colour. The estimated RGB of the cell pellets shows a small subset of available colours from GFP-like proteins (Table 2) applicable to plant-based meat applications. Table 2 Chromoprotein colour estimates from cell pellets The cell pellets were then subjected to heating in a dry heat block, from 40-100 °C increasing in 5 °C increments and being held at each temperature for 5 mins before being photographed. Table 3 provides an overview of colour changes during heating. From this heating experiment it was decided to upscale constructs 8 and 9 as the two extremes in thermal stability with SpisPink (construct 8) losing colour at 70 °C, whilst AmilCPpink (construct 9) didn’t lose colour even at 100 °C. Table 3 E.coli pellets containing chromoproteins thermal denaturation temperature *✓ = Maintained colour, X = Lost colour AmilCP-Pink Upscale and product testing Example Once protein expression was established, 10 X 1L cultures were in LB broth containing 50 μg/mL kanamycin and grown at 37 °C with shaking until a OD600 = 0.6-0.8 when protein induction was induced with 0.2 mM IPTG at 18 °C overnight. The cells were then harvested by centrifugation and resuspended in 5mL/g cell pellet Ni-NTA lysis buffer containing 20 mM Tris, 150 mM NaCl, 5 mM imidazole pH 8.0. Cell lysis was performed using high pressure homogenisation. The lysate was clarified by centrifugation at 15,000 x g for 20 mins before collection and passing through a 0.2 μm PES syringe filter. The AmilCP- Pink protein was then purified using a HisPrep column connected to Cytiva Äkta purification system by elution with buffer containing 20 mM Tris, 150 mM NaCl, 250 mM imidazole pH 8.0. Fractions containing the eluted AmilCP-Pink protein were pooled and buffer exchanged into MilliQ water containing 10 mM NaCl, pH 7.5 using a HiPrep desalting column. The AmilCP-Pink was re-pooled, frozen, and lyophilized for later use. UV-vis and Thermal denaturation measurements of AmilCP-Pink The UV-visible spectrum of AmilCP-pink was first measured using a to understand the λ _max of the protein. Absorbance of 0.25-2 mg AmilCP-pink in buffer containing 20mM sodium phosphate, 50 mM NaCl, pH 7.0 was measured between 250-700 nm using a Shimadzu UV-1900i spectrophotomer equipped with a TMSPC-8 Tm analysis system. A 1 cm ^-1 pathlength multi-cell (8) quartz cuvette was used for the measurement. As can be seen in Figure 1, the λ _max = 558nm with a secondary shoulder at 524nm and a much smaller broad shoulder at 490nm. To confirm the precise thermal denaturation temperature of AmilCP-pink, absorbance of 0.25-2 mg of AmilCP-pink in buffer containing 20mM sodium phosphate, 50 mM NaCl, pH 7.0 was monitored at 490nm, 524nm and 558nm whilst heating of the sample using a Shimadzu UV-1900i spectrophotomer equipped with a TMSPC-8 Tm analysis system. The setup of the experiment was: 1) Start Temperature 25 °C 2) Start wait 10 sec 3) Ramp rate 2.0 °C/min 4) Measure wait 10 sec 5) Interval 2.5 °C 6) End temp 95 °C The absorbance of AmilCP-Pink at the three different wavelengths with increasing temperature is shown in Figure 2. What can be seen is that whilst there was some change in absorbance with increasing temperature, there was no loss in absorbance which shows the protein did not lose its pink/red colour. This was confirmed visually after the thermal denaturation experiment whereby the protein in the cuvette was still coloured. Because the protein colour remained a Tm analysis was not calculated. Burger trials containing AmilCP-Pink: Dry powdered ingredients, including binders, salt, flavours, and preservatives are combined with texturised vegetable protein (TVP). AmilCP-pink (0.2 %w/w final) was dispersed in water and then added to the dry ingredients and allowed to hydrate for 10 min. After hydration, canola oil emulsion is added and combined into the burger mixture. Finally, coconut emulsion particles are combined into the burger mixture. After chilling for a 30 mins, burger patties (113 - 125 g) are formed using a manual burger press or using burger fabricating equipment. Burgers are packed and frozen (-18 °C) until use. Cooking instructions: Cooked from frozen. Burger patties are placed on a hot grill (~220 °C) and cooked 4-5 minutes on each side until evenly browned and an internal temperature of 71 °C is reached. Cooked from thawed: burger patties are placed on a hot grill (~220 °C) and cooked 2.5- 3 minutes on each side until evenly browned and an internal temperature of 71 °C is reached. Cooking observations: The burger patties containing the AmilCP-Pink were cooked from thawed as above and noticeable blood-like water release occurred before the patty was flipped. After cooking until the patty reached an internal temperature of 71 °C, the outside of the burger patty had a distinct browning whilst the inside of the patty had some red colour loss but still some red/pink colour. Spis-Pink Upscale and product testing Example Once protein expression was established, 10 X 1L cultures were in LB broth containing 50 μg/mL kanamycin and grown at 37 °C with shaking until a OD600 = 0.6-0.8 when protein induction was induced with 0.2 mM IPTG at 18 °C overnight. The cells were then harvested by centrifugation and resuspended in 5mL/g cell pellet Ni-NTA lysis buffer containing 20 mM Tris, 150 mM NaCl, 5 mM imidazole pH 8.0. Cell lysis was performed using high pressure homogenisation. The lysate was clarified by centrifugation at 15,000 x g for 20 mins before collection and passing through a 0.2 μm PES syringe filter. The Spis-Pink protein was then purified using a HisPrep column connected to Cytiva Äkta purification system by elution with buffer containing 20 mM Tris, 150 mM NaCl, 250 mM imidazole pH 8.0. Fractions containing the eluted AmilCP-Pink protein were pooled and buffer exchanged into MilliQ water containing 10 mM NaCl, pH 7.5 using a HiPrep desalting column. The AmilCP-Pink was re-pooled, frozen, and lyophilized for later use. UV-vis and Thermal denaturation measurements of Spis-Pink The UV-visible spectrum of Spis-pink was first measured using a to understand the λ _max of the protein. Absorbance of 0.25-2 mg Spis-pink in buffer containing 20mM sodium phosphate, 50 mM NaCl, pH 7.0 was measured between 250-700 nm using a Shimadzu UV- 1900i spectrophotomer equipped with a TMSPC-8 Tm analysis system. A 1 cm ^-1 pathlength multi-cell (8) quartz cuvette was used for the measurement. As can be seen in Figure 3, the λ _max = 564nm with a slight secondary shoulder at 524nm and a much smaller broad shoulder at 490nm. To confirm the precise thermal denaturation temperature of Spis-pink, absorbance of 0.25-2 mg of Spis-pink in buffer containing 20mM sodium phosphate, 50 mM NaCl, pH 7.0 was monitored at 490nm, 524nm and 564nm whilst heating of the sample using a Shimadzu UV-1900i spectrophotomer equipped with a TMSPC-8 Tm analysis system. The setup of the experiment was: 1) Start Temperature 25 °C 2) Start wait 10 sec 3) Ramp rate 2.0 °C/min 4) Measure wait 10 sec 5) Interval 2.5 °C 6) End temp 95 °C The absorbance of Spis-pink at the three different wavelengths with increasing temperature is shown in Figure 4. What can be seen at 564 nm is a slow decrease in absorbance until ~50-60 °C followed by a dramatic increase in absorbance. This change in absorbance is due to a loss in colour followed by a precipitation of Spis-Pink until all the protein is precipitated and finally this precipitate falls out of solution causing a loss in the absorbance. This was confirmed visually after the thermal denaturation experiment whereby the protein in the cuvette had lost all starting colour and a protein precipitate was formed in the cuvette. A thermal denaturation analysis (Tm) analysis using the in-built software using the derivate method was then performed for 564 nm (Figure 5). The Tm is calculated as the temperature where there is a 50% change in the absorbance of the protein. The Tm for Spis- Pink at 0.25 mg/mL was calculated to be 66 ± 0.60 °C and decreased with increasing protein concentration. This temperature is ideal for replicating the loss of colour with safe cooking temperature. Burger trials containing Spis-pink: Dry powdered ingredients, including binders, salt, flavours, and preservatives are combined with texturised vegetable protein (TVP). Spis-pink (0.2 %w/w final) was dispersed in water and then added to the dry ingredients and allowed to hydrate for 10 min. After hydration, canola oil emulsion is added and combined into the burger mixture. Finally, coconut emulsion particles are combined into the burger mixture. After chilling for a 30 mins, burger patties (113 - 125 g) are formed using a manual burger press or using burger fabricating equipment. Burgers are packed and frozen (-18 °C) until use. Cooking instructions: Cooked from frozen. Burger patties are placed on a hot grill (~220 °C) and cooked 4-5 minutes on each side until evenly browned and an internal temperature of 71 °C is reached. Cooked from thawed: burger patties are placed on a hot grill (~220 °C) and cooked 2.5- 3 minutes on each side until evenly browned and an internal temperature of 71 °C is reached. Cooking observations: The burger patties containing the Spis-pink were cooked from thawed as above and noticeable blood-like water release occurred before the patty was flipped. After cooking until the patty reached an internal temperature of 71 °C, the outside of the burger patty had a distinct browning and the inside of the burger has completely lost the starting pink/red colour. PaxPink Upscale and product testing Example from Pichia pastoris PaxPink (non-fluorescent): Estimated RGB (Cell pellet): 174-67-63 The plasmid CPB-53-902 (ATUM) containing the PaxPink gene was digested with PmeI to linearise the plasmid. One µg of linearised plasmid was transformed into Pichia pastoris BG11 (ATUM) by electroporation. Positive colonies were selected on YPD+ zeocin (400 µg/mL) agar. One hundred colonies were streaked on minimal media with 1% (v/v) methanol as the only carbon source. The colonies that showed the brightest shade of pink were chosen to perform 250 mL cultures. Briefly, the colonies were inoculated in YPD+zeocin (400 µg/mL) broth and the cultures were grown overnight at 28 °C. The overnight cultures were used to inoculate 250 mL of SYN6 autoinduction medium (2 % (w/v) glucose and 2 % methanol) to an OD ₆₀₀ of 0.2. The cultures were grown for 120 h at 28 °C. To maintain the induction of the AOX1 promoter the cultures were spiked with methanol (final concentration 2%) at 72 h. The cells were then harvested by centrifugation and resuspended in 10mL/g cell pellet buffer A containing 50 mM MES, pH 6.1. Cell lysis was performed using high pressure homogenisation. The lysate was clarified by centrifugation at 38,000 x g for 20 mins before collection and passing through a 0.2 μm PES syringe filter. The PaxPink protein was then purified using a HiPrep SP FF column connected to Cytiva Äkta purification system by elution with buffer containing 50 mM MES, 1M NaCl, pH 6.1. A 0-50 % B elution over 8 CV was used and the absorabce at 280 and 550nm was monitored. Fractions containing the eluted PaxPink protein were pooled and buffer exchanged into 50 mM MES, 100nm NaCl, pH 6.1 using an Amicon 10kDa PES centrifuge filter. The PaxPink solution was then heated to 65 °C for 5 mins to precipitate any remaining P, pastoris proteins, which were then removed by centrifugation at 20,000 x g. The sample was then frozen for later use. UV-vis and Thermal denaturation measurements of PaxPink The UV-visible spectrum of PaxPink was first measured using a to understand the λ _max of the protein. Absorbance of 0.25-2 mg PaxPink in buffer containing 50 mM MES, 100nm NaCl, pH 6.1 was measured between 250-700 nm using a Shimadzu UV-1900i spectrophotomer equipped with a TMSPC-8 Tm analysis system. A 1 cm ^-1 pathlength multi- cell (8) quartz cuvette was used for the measurement. As can be seen in Figure 6, the λ _max = 550nm with a secondary shoulder at 515nm and a much smaller broad shoulder at 480nm. To confirm the precise thermal denaturation temperature of Spis-pink, absorbance of 0.25-2 mg of Spis-pink in buffer containing 20mM sodium phosphate, 50 mM NaCl, pH 7.0 was monitored at 480nm, 525nm and 550nm whilst heating of the sample using a Shimadzu UV-1900i spectrophotomer equipped with a TMSPC-8 Tm analysis system. The setup of the experiment was: 1) Start Temperature 25 °C 2) Start wait 10 sec 3) Ramp rate 2.0 °C/min 4) Measure wait 10 sec 5) Interval 2.5 °C 6) End temp 95 °C The absorbance of PaxPink at the three different wavelengths with increasing temperature is shown in Figure 7. At 550 nm, there was a slow decrease in absorbance until ~65 °C followed by an increase in absorbance, a drop in absorbance at 80 °C and then a dramatic increase in absorbance. This initial change in absorbance is due to a loss in colour followed. The drop in absorbance at 80 °C indicates a transition phase whereby the colour of the protein has been lost and precipitation starts to occur. This was confirmed visually after the thermal denaturation experiment whereby the protein in the cuvette had lost all starting colour and a protein precipitate was formed in the cuvette. A thermal denaturation analysis (Tm) was not performed as the drop in absorbance at 80 °C makes the calculation incorrect. From the data, it appears that PaxPink has a Tm of colour loss of ~65 °C and a full protein precipitation Tm of ~87 °C. The colour loss temperature is optimum for replicating the loss of colour with safe cooking temperature. *** Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is understood that the invention includes all such variations and modifications which fall within the spirit and scope of the present invention.