A method for the manufacture of a processed cheese

Abstract

There is provided a method for the manufacture of a processed cheese, the method comprising: (i) providing a dairy concentrate having: (a) a dry matter content of from 20 to 49wt% based on the weight of the concentrate; (b) a fat content of 30 to 70wt%, based on the dry matter content; and (c) a casein to fat ratio of from 1:2 to 2:1; (ii) pasteurising and homogenising the dairy concentrate to form an emulsion; (iii) adding ingredients to the emulsion which comprise at least: (A) milk fat, and (B) one or more emulsifying salts, wherein at least the (A) milk fat is added using an inline venturi dosing inlet; (iv) heating the emulsion after step (iii) to a first emulsion temperature, without steam addition, by ohmic heating and / or cavitation treatment; and (v) creaming the emulsion after step (iv) at a second emulsion temperature of at least 70⁰C to form a processed cheese; wherein the first emulsion temperature is at least 5⁰C higher than the second emulsion temperature.

Description

[0001] A method for the manufacture of a processed cheese

[0002] The present invention relates to an improved method for the manufacture of a processed cheese. In particular, the inventive method is capable of providing a processed cheese more quickly, more reliably / consistently and with a lower process complexity.

[0003] Processed cheese (also known as process cheese) is a well-known class of cheese-based products which was first developed back in 1911 and was first described in US1186524 (James Lewis Kraft). Processed cheeses typically have a longer shelf-life and a wider utility than conventional cheeses. They tend to have better melting properties (they melt better and heating them does not tend to alter the taste or the texture) and a more consistent appearance (compared to the variance in natural cheeses). Given that processed cheese is mass-produceable, it also typically has a lower cost.

[0004] Consumers are already very familiar with cheese slices as an embodiment of processed cheese. These often take the form of an individually wrapped cheese having a consistent colour and thickness, and may also be referred to as "singles" or "burger cheese". Other forms of processed cheese include dips, spreads and individually portioned products (such as metal-wrapped triangles). While specific recipes will vary between these products, especially the solids levels necessary to achieve the right consistency, all of these products demonstrate the flexibility of processed cheese.

[0005] Processed cheese is a product made from cheese mixed with an emulsifying agent. It typically includes additional ingredients such as vegetable oil, salt, colouring, flavourings and sugar. In general, processed cheese typically contains around 50-60wt% cheese and the balance of other ingredients.

[0006] Emulsifying agents (also known as emulsifying salts) are key to the product being meltable without the fat separating from the protein. A traditional cheese consists of individual fat globules trapped in a network of casein, with calcium holding the casein molecules together. With prolonged heating, the typical result is a lumpy combination of protein gel and liquidfat on top. Processed cheese adds the emulsifying salts as a calcium-sequestering agent to stop calcium from being able to hold this casein network together. Smaller groups of linked casein molecules are then able to better mix into the fat when melted, forming microscopic droplets instead of large lumps. Common calcium-sequestering agents include sodium phosphate, potassium phosphate, tartrate, and citrate.

[0007] The book "Processed Cheese Science and Technology" (Woodhead Publishing 2022), edited by Mamdouh El-Bakry et al. provides a solid foundation to the technology of processed cheese.

[0008] W02020 / 051527 discloses methods of making a gas-containing food product. In particular, it focuses on methods of making a dairy product over multiple seasons when the supply of fresh milk varies 40% over the course of the seasons. Some embodiments include methods of making processed cheese.

[0009] There remains a need for a faster and more consistent approach to the manufacture of a wide range of processed cheese products. Accordingly, it is an object of the present invention to provide an improved method for a production of a range of processed cheese products, or at least to tackle problems associated therewith in the prior art or provide a commercially viable alternative thereto.

[0010] According to a first aspect the present invention provides a method for the manufacture of a processed cheese, the method comprising:

[0011] (i) providing a dairy concentrate having:

[0012] (a) a dry matter content of from 20 to 49wt% based on the weight of the concentrate;

[0013] (b) a fat content of 30 to 70wt%, based on the dry matter content; and (c) a casein to fat ratio of from 1:2 to 2:1;

[0014] (ii) pasteurising and homogenising the dairy concentrate to form an emulsion;

[0015] (iii) adding ingredients to the emulsion which comprise at least:

[0016] (A) milk fat, and(B) one or more emulsifying salts,

[0017] wherein at least the (A) milk fat is added using an inline venturi dosing inlet;

[0018] (iv) heating the emulsion after step (iii) to a first emulsion temperature, without steam addition, by ohmic heating and / or cavitation treatment; and

[0019] (v) creaming the emulsion after step (iv) at a second emulsion temperature of at least 70°C to form a processed cheese;

[0020] wherein the first emulsion temperature is at least 5°C higher than the second emulsion temperature.

[0021] The present disclosure will now be described further. In the following passages different aspects / embodiments of the disclosure are defined in more detail. Each aspect / embodiment so defined may be combined with any other aspect / embodiment or aspects / embodiments unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.

[0022] The inventors have found that the invention provides an improved method of reliably producing an equivalent processed cheese product more quickly and with lower complexity. Consequently, the production can be more efficiently achieved. The method avoids the need to pre-make cheese as a qualifying product (i.e. meeting statutory definitions) - instead this can be made during the process directly through a concentration step, preferably microfiltration. Venturi addition of the powder ingredients gives an improved faster formation of the intermediate. Heating without the conventional steam addition gives a more reliable product quality as there is no variable water addition that leads to product inconsistencies.

[0023] The method of the invention relates to the manufacture of a processed cheese, in particular a dairy-based processed cheese. As discussed above, processed cheese is a well-known class of product, with a range of different embodiments ranging from cheese slices to dips and spreads.The method comprises a first step (i) of providing a dairy concentrate. The dairy concentrate is obtained from dairy ingredients and has been subjected to concentration steps such that it is more concentrated than a standard dairy product, i.e. whole milk. The concentrate can be defined by its dry matter content, its fat content and its casein to fat ratio. These features define the nature of the concentrate and also limit how it can be obtained. They also contribute to ensuring that the intermediate steps of the process can involve the formation of a material meeting a statutory cheese definition (which will vary depending on the jurisdiction) and, hence, that the final product is considered to be a processed cheese.

[0024] The method can advantageously be adapted for a wide range of processed cheeses. The type of the final product can be achieved just by controlling the dry matter of the starting concentrate (in particular, with different product rheologies). The dry matter content changes through the process as further ingredients are added, but starting with a higher dry matter content inevitably leads to a final product also having a higher dry matter content. The dairy concentrate comprises has a dry matter content of from 20 to 49wt% based on the weight of the concentrate. Specific preferred ranges are provided below for each different type of conventional processed-cheese product, but it should be appreciated that the preferred sub-ranges can also be used for other processed-cheese product forms and are not inextricably linked to the preferred types exemplified.

[0025] In one embodiment the processed cheese is a cheese slice and the dry matter content of the dairy concentrate is from 35 to 40wt%. This is towards the higher end of the broader range of dry matter content and this provides the more resilient structure necessary to provide a self-supporting cheese slice. That is, a cheese-slice product can be readily handled without falling apart or smearing. A cheese-slice product may be individually wrapped, or may be stacked together and wrapped in bulk.

[0026] In one embodiment the processed cheese is a self-supporting spread shape and the dry matter content of the dairy concentrate is from 30 to 35wt%. As the dry matter content of the starting material decreases the processed cheese being produced becomes softer. An example of a self-supporting spread shape is a cheese triangle. These are filled into pre-folded aluminium packaging shapes. If the aluminium is removed, the spread retains its shape. However, if spread with a knife onto a surface it will plastically yield.

[0027] In one embodiment the processed cheese is a spread and the dry matter content of the dairy concentrate is from 25 to 30wt%. A spread is typically provided in a tub and is scraped out and used with a knife. Such spreads tend to be shape-retaining out of the fridge, in that they do not slosh around in the container.

[0028] In one embodiment the processed cheese is a dip and the dry matter content of the dairy concentrate is from 20 to 25wt%. The lowest dry matter provides the least shape-retaining product. A dip may still be shape-retaining but may also flow over time. By having a sticky flowable material it is easy to use as a dip and it will cling to any dipped food article.

[0029] It should be noted that the description of "self-supporting" or "shape-retaining" relates to the final product at its storage temperature. For these products and especially spreads and dips this will typically be at fridge to room temperature (e.g. 5-20°C, preferably 5-8°C). It will be appreciated that during manufacture and before cooling, the processed cheese in the creaming process will be liquid and hot-fillable.

[0030] The dairy concentrate has a fat content of 30 to 70wt%, based on the dry matter content. Preferably the fat content of the dairy concentrate is from 40 to 60wt%. The fat content varies with the type of cheese that is being used or emulated. For example, Gouda has a fat content of about 30wt%, Edam and Mozzarella of about 40wt% and Emmental of about 45wt%. The fat content is therefore selected depending on the nature of the desired final product.

[0031] The dairy concentrate has a casein to fat ratio of from 1:2 to 1:0.5 (by weight). Preferably the casein to fat ratio is from 1:0.6 to 1:1.8. The casein to fat ratio is distinct from a protein to fat ratio which is also used in the industry to define cheeses. However, the casein to fat ratio is more critical to defining the nature and structure of the final processed cheese product. Theprecise ratio will vary depending on the cheese type that is being used or emulated. For example, when making an Emmental-type product a casein to fat ratio of 1:1 is desirable.

[0032] The dairy concentrate is preferably provided by microfiltration (MF) of non-skimmed milk (i.e. dairy milk from cows, goats or sheet and preferably cows), optionally with diafiltration and / or ultrafiltration. Preferably the dairy concentrate is provided by microfiltration of whole milk, as the non-skimmed milk, preferably using an MF membrane having a pore size of less than 1pm, preferably less than 0.5pm and more preferably less than 0.1pm (while still being an MF filtration process). It is the retentate or concentrate that is used as the concentrate of the invention. In the case that the process also uses ultrafiltration, the molecular weight cut-off (MWCO) is between 10 and 150 kDa. The preferred size is 10 kDa to concentrate the whey proteins, too. If this is not the case, the cutoff is bigger and is between 25 and 150 kDa.

[0033] It is unusual to perform MF of whole milk. This is because, while MF is routinely used for removing bacterial load in skimmed milk, it cannot be done with whole milk on a suitable scale because the milk fats clog the pores (even at the conventional larger 1.4pm sizes) - this cannot be sustained on the volume that needs to be treated for handling commercial milk volumes. MF is desirable in the present invention because it reduces the whey protein content, lactose and minerals which pass into the permeate, i.e. the MF removes those dairy components in the retentate which are not normally in cheese. We are therefore able to achieve a qualifying cheese composition more quickly from the retentate (or concentrate). There is no need to screen out bacteria in this step, due to the other pasteurisation and heat-treatment steps. If necessary, the fat levels can then be supplemented with added dairy fat, such as anhydrous milk fat and / or cream.

[0034] Alternatively the dairy concentrate is preferably provided by microfiltration of skimmed milk, optionally with diafiltration and / or ultrafiltration, and subsequent addition of dairy cream. In the same way the MF step helps to reduce the whey protein content, lactose and minerals into the permeate which are not normally in cheese. The retentate is then supplemented with dairy cream in order to establish the necessary levels of fat.In a second step the dairy concentrate is subjected to (ii) pasteurising and homogenising to form an emulsion. These steps ensure that the dairy concentrate forms an emulsion having a suitable microbial stability. The steps of pasteurising and homogenisation can be performed simultaneously or in either order. Both are conventional steps in the production of dairy ingredients and suitable pasteurising conditions can be readily selected, such as heating to at least 72°C for at least 15 seconds. Higher temperatures will be associated with shorter times and lower temperatures require longer treatment times.

[0035] Homogenisation may be performed in one or more pressure reductions steps (typically two). A conventional homogenisation performed in the dairy industry might, for example, have a first step at 200-300 Bar and then a second step at 40-60 Bar. The exact nature of this step is not critical and many different approaches to homogenisation are known, provided that an emulsion is formed. In general, the second step of a two-step homogenisation is 0.2-times the total pressure drop. Exemplary homogenisation steps include a 200 Bar first step, a 50 Bar second step (often reported as 250 Bar homogenisation).

[0036] There follows a step of (iii) adding ingredients to the emulsion, at least some of the ingredients being added using an inline venturi dosing inlet. The milk fat is added at least using the inline venturi dosing inlet. The use of an inline venturi dosing system allows for the quick introduction of ingredients into the emulsion and is able to work for the addition of liquid or powder ingredients. The ingredients are drawn into the emulsion and readily disperse. Depending on the nature of the ingredients it may be possible to pass the emulsion through more than one venturi dosing inlet (or the same one in batches) to introduce each of a number of different ingredients. Preferably the ingredients are premixed, such that they can be added in a single step (or multiple steps using the same feed powder). The fewer steps required the simpler the process.

[0037] Preferably step (iii) is performed at a temperature (herein the third emulsion temperature) of 15 to 30°C. That is, preferably the ingredient addition occurs at or about roomtemperature. When the dairy fat is added as a liquid it may have been preheated to soften and liquefy it.

[0038] Preferably at least some of the ingredients are pre-blended (such as dry mixing of powders) and the addition is performed in one or two dosing steps, preferably in one dosing step. One step is desirable, but may not always be possible to meet statutory requirements about preforming the cheese before addition of the emulsifying salts. Hence, these may need to be added in a second ingredient addition step. A dsing may take place with continual cycling of the emulsion past the inlet. Preferably all addition is on a batch basis and all using the presence of the magnetic field.

[0039] Preferably the inline venturi dosing inlet further comprises a magnetic field generator within a powder-dosed-emulsion flow path. Preferably the magnet is a permanent magnet. The benefit of having the magnet present is seen in the average size of the droplets of the emulsion and the greater the magnetic field strength the better. Commercial magnets are typically limited to about 10,000 gauss. Preferably the field strength is at least 2000 gauss, more preferably at least 4000 gauss, and in most instances up to 10,000 gauss. This has been found to improve the product structure, compared to conventional high-shear mixing. This gives improved functionality to the proteins and is much faster (on a minutes or seconds basis, compared to hours of blending). The structural differences can be seen by conformal laser scanning microscopy in a qualitative sense. The product differences are improved sensory and cohesiveness.

[0040] The ingredients comprise at least (A) milk fat and (B) one or more emulsifying salts. The milk fat is preferably butter or anhydrous milk fat (AMF). The emulsifying salts are preferably selected from phosphates, tartrates and citrate salts. Preferably the one or more emulsifying salt comprises calcium phosphate. The emulsifying salts are preferably added as a liquid.

[0041] Further ingredients may be added at this point in the process. These are discussed below and each may be used alone or in a combination of one or more from the list. These include ground natural cheese. This is a common ingredient in processed cheese addition and helpsto provide a cheesy flavour. The cheese may be of any conventional cheese type, including for example, Gouda, Emmental, Cheddar and the like. This is made in a separate conventional process, ground to obtain a fine powder and added as described herein.

[0042] Other additions also include a cheese flavouring, such as EMC (Enzyme modified cheese) and / or EMDI (Enzyme modified dairy ingredients). These can assist with any flavour losses arising from the process, particularly if there is no (or low levels of) addition of grinded cheese.

[0043] Further dairy ingredients may be desirably added. These include skimmed milk powder, casein, whey, whey protein, and lactose. These may be obtained as filtration fractions, such as a permeate powder, which can then be used in the process. These can, for example, be obtained by further processing the MF permeate from earlier in the process or can be used as by-products from other dairy processes such as natural cheese manufacture.

[0044] Dairy products are a common source of salt and it may be desirable to supplement the processed cheese product. Typically salt addition involves NaCI, but KCI or other low-sodium salt additives may also desirably be used.

[0045] The ingredients may additionally include one or more pH regulators, preferably lactic acid and / or citric acid. Other stabilisers, buffers and the like that are common in processed cheese manufacture may also be added at this point.

[0046] The majority of ingredients except the emulsifying salts and, in some embodiments, the dairy fat, are provided in powdered form.

[0047] The method then involves (iv) heating the emulsion after step (iii) to a first emulsion temperature, without steam addition, by ohmic heating and / or cavitation treatment. It should be noted that the high shear of the cavitation leads to significant heating of the treated material. Although steam heating is ubiquitous in processed cheese manufacture because of the speed and efficacy of the heating achieved, the inventors have found thatthis should be avoided. The steam heating leads to the addition of water which may need to be removed and this leads to undesirable variation within and between batches of the processed cheese. Furthermore, high temperature pressurised steam treatments have been found to lead to a loss of protein functionality which should desirably be avoided.

[0048] Preferably the temperature in the heating step (iv) (herein the first emulsion temperature) is at least 90°C, preferably 95 to 150°C, more preferably 95 to 140°C and most preferably 95 to 110°C. This range of temperatures achieves a good activation of the emulsifying salts. The duration of the heating step will be selected based on the temperature, with higher temperatures requiring shorter holding times. By way of example, a treatment at 135 °C may be performed for only a few seconds, whereas a treatment at 98 °C could be performed for around 40 seconds. In general, the heating step will be performed for less than 2 minutes, preferably less and 1 minute. Preferably more than 2 seconds, more preferably more than 10 seconds.

[0049] The process can involve ohmic heating or cavitation treatment, but preferably comprises a combination of the two. The inventors have found that the optimum balance of ohmic and cavitation treatment depends on the target temperature. In particular, for higher temperatures such as up to UHT temperatures (i.e. up to 150°C), it is difficult to have sufficient heat input by the cavitation process and therefore it is desirable to initially cavitate the material and then provide the final heating energy by ohmic heating. This is the desirable approach in the region of from 100 to 150°C. For temperatures below 100°C, such as 75-100°C, it may be desirable to perform the steps in the other order. Performing cavitation and then ohmic heating is, however, generally preferred for control of the final temperature.

[0050] The method then comprises (v) creaming the emulsion after step (iv) at a second emulsion temperature of at least 70°C to form a processed cheese. The first emulsion temperature is at least 5°C higher than the second emulsion temperature - that is, there is always a temperature drop of at least 5°C, preferably at least 10°C and most preferably at least 15°C between the heat-treatment step (iv) and the creaming step. Preferably the emulsion is notcooled down below 70°C between steps (iv) and (v). Creaming is a known step in processed cheese manufacture and is used to build texture of the final emulsion containing the emulsifying salts. Significant increases in the viscosity can be achieved.

[0051] Rennet is a desirable addition for some processed cheese products. This may be particularly desirable for countries and products where the rennet is part of the definition of the cheese product to be made. When rennet is added, preferably it is added to the dairy concentrate emulsion before step (iii), preferably to the dairy concentrate before step (ii).

[0052] Preferably in step (iv) the emulsion after step (iii) is pre-warmed to a temperature of from 50 to 70°C before the cavitation treatment, preferably using a heat-exchanger recovering heat from the product of step (v). This helps to improve the efficiency of the process. The prewarming may be followed by the cavitation and followed by ohmic heating.

[0053] Preferably step (v) is performed at a temperature of 75 to 90°C for at least 30 minutes, preferably at least 1 hour. Preferably step (v) comprises monitoring the rheology of the emulsion to determine an end-point achieving a desired final texture. This acts as a safety check, since a batch which does not build in texture can be discarded. The texture building typically provides a significantly greater firmness during this step.

[0054] Preferably the processed cheese is hot-filled into final packaging. This ensures microbial safety and particularly applies to triangles, slices, dip and spread.

[0055] The present method rests on four key innovation pillars that together provide an optimised and versatile method for the production of a range of processed cheeses.

[0056] The first pillar is to use a dairy concentrate such as a milk concentrate with high total solids. This is ideally produced by microfiltration (MF) or MF combined with ultrafiltration (UF) as a major ingredient instead of natural cheese. Usually, green (non-ripened) as well as ripened natural cheese is used as an ingredient for process cheese. The green natural cheese isimportant to deliver casein for a good network formation and the ripened natural cheese is delivering the typical cheese taste coming from the ripening process.

[0057] For the present invention the milk concentrate can be used only as a replacement of green natural cheese together with an amount of ripened natural cheese as a source of typical cheese flavor. In this embodiment the cheese still contains genuine cheese ingredients. In another embodiment it is possible to use only the dairy / m i I k concentrate and fully replace natural cheese from the cheese formula. Then, it would be desirable to use cheese flavouring, such as Enzymatically Modified Cheese (EMC) or Enzymatically Modified Dairy Ingredients (EMDI).

[0058] The second pillar lies in the new venturi mixing technologies, especially those with a magnetic field generated to improve the emulsion. These approaches are optimal as they were found to give excellent mixing at a high speed. The design of the venturi powder feeding system is optimal because it is a simple part which has a low complexity and high reliability.

[0059] The third pillar lies in the replacement of the industry standard direct steam injection. The principle of Ohmic heating technology is that heat is produced by the passage of an electric current through a conductor, whereas cavitation is highly energetic mixing that leads to heating of the mixed material. Replacing steam with Ohmic heating technology and / or cavitation is desirable because there is no dilution of the product by a condensate as it is the case for the steam injection. Thus, the totals solids of the cheese are not affected, as it is by variations in the line speed during pumping processed cheese through a steam-injection cooker. This is a typical issue of which the inventors have practical experience. In addition, when present, the cavitation can functionalise the protein content further.

[0060] The fourth pillar is rheological profiling and monitored creaming of the process cheese. Rheological profiling can be done using Rapid Visco Analysers (RVA) that are able to heat and shear the respective product at very precisely defined conditions. During these measurements the hot viscosity of the product is monitored and a creaming reaction of theprocess cheese can be determined. The RVA measurements allows the operator to learn how the product behaves under controlled heat and shear conditions and enable processing the cheese under adjusted setings to receive a finished product with the desired rheological properties. Moreover, the monitoring allows a further safety check in the process, since a batch where the texture does not correctly develop can be discarded as unsuccessful.

[0061] The invention will now be described further in the following figures. In which:

[0062] Figure 1 shows a conventional processed cheese manufacturing process.

[0063] Figure 2 shows a flowchart of the key process steps.

[0064] Figure 3 shows the venturi powder addition system.

[0065] Figure 4 shows CLSM images of processed cheese made from milk concentrate with new and standard mixing devices.

[0066] Figure 5 shows Processed Cheese Slices with different heat treatment: A) Ohmic heating and b) Direct steam injection. The dark arrowed marks are protein and the rounded balls and globules are fat.

[0067] Figure 6A shows Cryo-SEM image of a processed cheese slice heated by the standard steam. Figure 6B shows Cryo-SEM image of a processed cheese slide by Ohmic heating.

[0068] Figure 7A shows viscosity development of standard processed cheese during creaming at 82°C and 80rpm.

[0069] Figure 7B shows viscosity development of processed cheese manufactured according to the new principle (milk concentrate, mixing, cavitation technology) during creaming at 82°C and 80rpm.Figure 7C shows viscosity development of processed cheese manufactured according to the new principle (milk concentrate, mixing, Ohmic technology) during creaming at 82°C and 80rpm.

[0070] A conventional method for the production of a processed cheese product is shown in Figure 1. This process begins with the production of a natural cheese 105 which requires ageing for more than 60 days to arrive at a matured cheese product. The matured cheese is then subjected to a cheese grinding step 110. The ground cheese is then passed to a mixing step 120 where preprepared additives 115 are added. The preprepared additives include powder ingredients, such as fats, acidity regulators and emulsifying salts, as well as water.

[0071] The mixing step 120 typically involves both high shear mixing and low shear blending. After thorough mixing there is a cooking step 125 involving direct steam injection. The cooked process cheese is then filled 130 into packaging and cooled 135.

[0072] The method of the invention relates to the manufacture of a processed cheese product. The method involves a first step 205 of providing a dairy concentrate. The dairy concentrate is selected based on the product desired, in particular ensuring that the dry matter content matches the desired firmness of the final product. The dairy concentrate has at least a dry matter content of from 20 to 49wt% based on the weight of the concentrate, a fat content of 30 to 70wt%, based on the dry matter content, and a casein to fat ratio of from 1:2 to 2:1.

[0073] In a second step 210 the dairy concentrate is subjected to pasteurising and homogenising. These steps ensure that the dairy concentrate forms an emulsion having a suitable microbial stability. The steps of pasteurising and homogenisation can be performed simultaneously or in either order. Both are conventional steps in the production of dairy ingredients and suitable pasteurising conditions can be readily selected, such as heating to at least 72°C for at least 15 seconds. Higher temperatures will be associated with shorter times and lower temperatures require longer treatment times.Homogenisation may be performed in one or two pressure reductions steps. A conventional homogenisation performed in the dairy industry might, for example, have a first step at OOBOO Bar and then a second step at 40-60 Bar.

[0074] Ingredients are separately provided in a third step 215. These include at least milk fat, which may be butter or anhydrous milk fat, for example, and one or more emulsifying salt. These ingredients may be pre-mixed. These are then added to the emulsion in step 220 using an inline venturi dosing inlet. This ensures thorough mixing in a short process time period. Water may be added at this stage, if desired, i.e. after forming the concentrate and before cooking). The emulsifying salt may be added in a separate conventional mixing step.

[0075] In a fifth step 225 the emulsion comprising the added powder ingredients is subjected to a heating step, without steam addition, by ohmic heating and / or cavitation treatment. This process step is performed at a temperature higher than that of the subsequent creaming, such that the temperature after this step is allowed to subside for the creaming.

[0076] In a sixth step 230 the mixture is subjected to creaming. This is a heat-treatment step which is performed at a temperature of at least 70°C to form a processed cheese. Desirably the creaming involves slow stirring or agitation of the emulsion. During this step the rheology of the creamed emulsion is monitored until a desired texture has developed. While creaming steps are known in the manufacture of certain cheeses, such as cream-cheeses, it is not a conventional step in producing processed cheeses.

[0077] The creamed emulsion is then filled into a container in a seventh step 235. This is desirably a hot-filing step, since that ensures microbial stability. The packaging will vary depending on the product type. For cheese-slices, the creamed emulsion will be cast as a sheet, cut, stacked and wrapped. For cheese triangles, the creamed emulsion is filled into pre-formed foil moulds and wrapped. For cheese spreads, the creamed emulsion is filled into tubs and sealed.As shown in Figure 3, the concentrate is passed through a flow restriction. This increases the speed of the concentrate flow and decreases its pressure. This has a consequential venturi effect, drawing powder quickly in through the powder inlet and ensuring good mixing with the concentrate. Immediately after the introduction of the powder there is an optional magnetic field generator arranged within the duct. This has been found to improve the thoroughness of the mixing process and allow a product to be obtained more quickly.

[0078] Examples

[0079] The inventions will now be described further in relation to the following non-limiting examples.

[0080] Example 1 - manufacture the product using the new methods

[0081] a. Milk handling and preparation

[0082] Raw milk is separated into skimmed milk and cream using a clarifier separator after milk reception. This is followed by a pasteurization step at 72°C for 15 to 45 seconds. Both products can then be buffered in their respective tanks. The standardization of the fat to casein level can take place on the next step. In this example the ratio between fat and casein is 1:1. Alternatively, the standardization can take place directly after the pasteurization. This standardized milk goes in a separated buffer tank. Preferably the milk is not homogenized during these processing steps.

[0083] b. Filtration step

[0084] The concentrate is obtained with a microfiltration at an inlet temperature of around 50°C. The standardized milk is brought to this process temperature via a pre-heater (plate heat exchanger with heat recovery sections for cooling the permeate stream on the way back). The used filtration unit uses ceramic multitube elements with a pore size of 0.1pm and longitudinal permeability gradient (Pall Membralox GP membrane, material alpha-alumina-oxide). The useddiameter is 4mm. After a pre-concentration of the milk, diafi Itration steps with reverse osmosis are performed with the permeate serving to flush the whey proteins, lactose and minerals out. In parallel the level of fat and casein increase to the target level. The chemical compositions of permeate and concentrate are checked over time to guarantee the final composition of the cheese-similar product. If the quality is the right one, the concentrate is pre-heated to temperature (60-65°C) and homogenized around 150bar / 30bar. A high heattreatment to stabilize the microbiological status with temperatures around 75 to 85°C for 15 to 45 seconds may follow. The last step before storage is a cooling step. The product can be stored between 4 and 8°C.

[0085] c. Ingredients preparation

[0086] Before powders and liquids can be mixed in, they must be prepared. In this example all powder excluding the emulsifying salts can be pre-mixed to a blend. Powders for a final batch size are skim milk powder (medium heat; approx. 16kg), Inulin (7kg), sodium chloride (2.8kg) and rennet casein (to adjust the final casein level; 2kg). AMF (0.3kg) to stabilize the final fat level must be melted. The temperature of the molten AMF should be higher than 50°C. The emulsifying salts (5kg) are added in liquid form. They are therefore pre-dissolved in a further batch of water (25kg). A continuous stirrer helps to release the powder.

[0087] d. Cheese preparation

[0088] For this batch approx. 50 kg of matured cheese is needed. The source is Emmental cheese. For a good mixing result, this cheese must be grated into 3 to 6mm pieces.

[0089] e. Mixing step

[0090] The concentrate with a target dry matter of 38g / 100g (87kg) is added to the empty mixing unit without any pretreatment. The mixer operates in a batch mode. In the system of this unit a certain volume of water is inside. This mustconsider to create the right final composition. The pump should be set not too low to ensure the Venturi effect is observed.

[0091] After the milk concentrate has been added, it is pumped into circulation. Then the ground cheese has been added in the buffer of the mixing unit directly. If the process conditions are constant, the powder blend is added. The speed of the feed should not be too fast to ensure a uniform mixing process. After a short additional stabilization phase of 30s, the melted AMF is added. Before the emulsifying salt solution is added, half of the lactic acid (1.2 kg) is incorporated. With the other half the is used for adjusting the target pH-value of 5.45. The mix is immediately pumped into the next processing step.

[0092] f. Heating steps

[0093] The first unit used for the heating is a tubular heat exchanger, which heat the product from the mixing temperature up to 60°C. The subsequent step is carried out with a Cavitator, which heats the product to a final temperature of 98.5°C. The product temperature is held for at least 40s. The tubular heat exchanger cools the temperature down to a temperature between 80 and 85°C for the next processing step.

[0094] g. Creaming step

[0095] The last step before filling is the creaming step. This takes place in a tank with an appropriate agitator and indirect temperature correction options. Approximately 80kg of the product is in such a tank. The texture of the product will change as a result of the temperature, shear and time exposure. The texture building is controlled by offline methods like Rapid Visco-Analyzer.

[0096] h. Filling

[0097] After reaching a certain viscosity the product is pumped to the filling machine. In this case it is a single- slice-packaging machine. In this machine the packed product is cooled down to a temperature lower than 8°C. The final cooling to 4°Cis done in a cooling room.

[0098] Illustrative Examples

[0099] Example: Mixing

[0100] The positive effect of the venturi missing device can be seen, for example, in the distribution and size of the fat globules (Figure 4). The samples consisted of fat droplets and aggregates of proteinaceous material. The sample made with the new mixing unit contained much smaller fat droplets (up to 25pm) and protein aggregates. The sample made with a standard batch mixing device contained much larger fat droplets up to 60pm and protein aggregates.

[0101] In addition, centrifugal stability measurements (Setings: 40000xg for 20min at 30°C) were taken on the sample using conventional mixing and the venturi addition. The % serum for the new method was less than 1.5% compared to over 10% for the conventional mixer. The venturi addition therefore has a positive effect on the serum holding capacity of processed cheese even with a high moisture level.

[0102] Example: Benefit of Ohmic heating

[0103] In Figure 5 the Confocal laser scating microscopy images are shown for processed cheese slices with different heat treatment technologies. The product was produced with the described method without any ground cheese. The heat treatment was the same. The used equipment was different. Figure 5-A shows the protein and fat distribution, and status of a treated milk concentrate with Ohmic heating. The concentrate in figure 5-B was treated with direct steam injection. In principal both samples look similar. There may have been a higher degree of fat droplet coalescence in the samples made using the direct steam injection than 'Ohmic'.

[0104] The Cryo-SEM analytics confirm the differences between the two different heating technologies (Figure 6). In both cases, the processed cheese was produced from milk concentrate.It is not only the microstructure that shows differences between the two technologies used. These can also be recognized in the application. In horizontal toasting applications (slice on toast) the ohmic heated product tasted slightly more cheesy and had a more elastic and chewy texture. In oven melting tests (slice on toast) the ohmic heated product showed more elastic properties when disturbed with a spoon compared to the steam-heated sample.

[0105] Example: Effect of Cavitation technology

[0106] The hydrodynamic cavitation technology alone also produces an improved micro-structure. CLSM images of the standard processed cheese technology show a coarser population of fat droplets compared with ohmic and cavitation heated samples.

[0107] A further comparison shows the positive effect of the cavitation technology on the microstructure. The coarser structure of the processed cheese from grinded cheese is gone. The differences to the milk concentrate samples are smaller.

[0108] Example: Creaming

[0109] Due to the texture and structure modifications during the creaming treatment the viscosity changes in case of the new process. The curve in Fig.7A shows the behaviour of the processed cheese treated by the standard technology units. In contrast, the two diagrams below show an increase in viscosity over time and in a significant higher viscosity range (Fig.

[0110] 7B and 7C).

[0111] The term "comprising" as used herein can be exchanged for the definitions "consisting essentially of" or "consisting of". The term "comprising" is intended to mean that the named elements are essential, but other elements may be added and still form a construct within the scope of the claim. The term "consisting essentially of" limits the scope of a claim to the specified materials or steps and those that do not materially affect the basic and novel characteristic(s) of the claimed invention. The term "consisting of" closes the claim to the inclusion of materials other than those recited except for impurities ordinarily associated therewith.It will be understood that, although the terms "first", "second", etc. may be used herein to describe, for example, various features (e.g. the first and second emulsion temperatures), the features should not be limited by these terms. These terms are only used to distinguish one oil fraction, for example, from another or further oil fraction.

[0112] The foregoing detailed description has been provided by way of explanation and illustration and is not intended to limit the scope of the appended claims. Many variations in the presently preferred embodiments illustrated herein will be apparent to one of ordinary skill in the art and remain within the scope of the appended claims and their equivalents.

[0113] For the avoidance of doubt, the entire contents of all documents acknowledged herein are incorporated herein by reference.

[0114] All percentages herein are by weight unless indicated to the contrary.

Claims

Claims:

1. A method for the manufacture of a processed cheese, the method comprising:(i) providing a dairy concentrate having:(a) a dry matter content of from 20 to 49wt% based on the weight of the concentrate;(b) a fat content of 30 to 70wt%, based on the dry matter content; and (c) a casein to fat ratio of from 1:2 to 2:1;(ii) pasteurising and homogenising the dairy concentrate to form an emulsion;(iii) adding ingredients to the emulsion which comprise at least:(A) milk fat, and(B) one or more emulsifying salts,wherein at least the (A) milk fat is added using an inline venturi dosing inlet;(iv) heating the emulsion after step (iii) to a first emulsion temperature, without steam addition, by ohmic heating and / or cavitation treatment; and(v) creaming the emulsion after step (iv) at a second emulsion temperature of at least 70°C to form a processed cheese;wherein the first emulsion temperature is at least 5°C higher than the second emulsion temperature.

2. The method according to claim 1, wherein:(i) the processed cheese is a cheese slice and the dry matter content of the dairy concentrate is from 35 to 40wt%; or(ii) the processed cheese is a self-supporting spread shape and the dry matter content of the dairy concentrate is from 30 to 35wt%; or(iii) the processed cheese is a spread and the dry matter content of the dairy concentrate is from 25 to 30wt%; or(iv) the processed cheese is a dip and the dry matter content of the dairy concentrate is from 20 to 25wt%.

3. The method according to any preceding claim, wherein the dairy concentrate is provided by:(i) microfiltration of non-skimmed milk, optionally with diafiltration and / or ultrafiltration; or(ii) microfiltration of skimmed milk, optionally with diafiltration and / or ultrafiltration, and subsequent addition of dairy cream.

4. The method according to claim 3, wherein the dairy concentrate is provided by microfiltration of whole milk, as the non-skimmed milk, using an MF membrane having a pore size of less than 1pm.

5. The method according to any preceding claim, wherein:(a) the fat content of the dairy concentrate is from 40 to 60wt%; and / or (b) the casein to fat ratio of the dairy concentrate is from 1:0.6 to 1:1.8.

6. The method according to any preceding claim, in which the inline venturi dosing inlet further comprises a magnetic field generator within a powder-dosed-emulsion flow path.

7. The method according to any preceding claim, wherein at least some of the ingredients added in step (iii) are pre-blended together and the addition is performed in one or two dosing steps, preferably in one dosing step.

8. The method according to any preceding claim, wherein step (iii) is performed at a third emulsion temperature of 15 to 30°C.

9. The method according to any preceding claim, wherein the ingredients in step (iii) further comprise:(C) cheese flavouring; and / or(D) natural cheese; and / or(E) casein; and / or(F) skimmed milk; and / or(G) salt; and / or(H) a pH regulator, preferably lactic acid and / or citric acid.

10. The method according to any preceding claim, wherein rennet is added to the dairy concentrate before step (iii), preferably before step (ii).

11. The method according to any preceding claim, wherein:(A) the milk fat is anhydrous milk fat;(B) the one or more emulsifying salt comprises calcium phosphate.

12. The method according to any preceding claim, wherein the first emulsion temperature is at least 90°C, preferably 95 to 110°C.

13. The method according to any preceding claim, wherein in step (iv) the emulsion after step (iii) is pre-warmed by cavitation treatment and then reaches the first emulsion temperature by ohmic heating.

14. The method according to claim 12, wherein in step (iv) the emulsion after step (iii) is pre-warmed to a temperature of from 50 to 70°C before the cavitation treatment, preferably using a heat-exchanger recovering heat from the product of step (v).

15. The method according to any preceding claim, wherein step (v) is performed at a temperature of 75 to 90°C for at least 30 minutes, preferably at least 1 hour.

16. The method according to any preceding claim, wherein step (v) comprises monitoring the rheology of the emulsion to determine an end-point achieving a desired final texture.

17. The method according to any preceding claim, wherein the processed cheese is hot-filled into final packaging.

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