RELATED APPLICATIONS

This application derives priority from New Zealand provisional patent application number 779809 filed on 6 September 2021 with WIPO DAS code D49B incorporated herein by reference.

TECHNICAL FIELD

Described herein are dissolved air flotation (DAF) stream and DAF-like stream processes and products including offal processes and product. More specifically, a method of producing a non-aqueous DAF product, a free fat composition and protein complex from a raw DAF stream and products therefrom are described. Processing of DAF-like streams such as DAF-like streams comprising offal, bone meal, meat, or fish/marine are also described. DAF or DAF-like stream processing plants, an associated vacuum dryer and an animal feed ingredient are also described.

BACKGROUND ART

Dissolved air flotation (DAF) streams are typically streams resulting from dairy or meat processing factories made up of a variety of components but typically a mix of proteins, fats and water (80-90%). DAF streams are common from dairy factories but may also result from other food processing environments such as abattoirs. DAF-like streams may have similar compositions to DAF streams hence are discussed together with DAF streams below. Examples of DAF-like streams are offal, bone meal, meat, or fish/marine origin materials. Aspects of DAF stream or DAF-like stream background and features may be interchangeable and reference to one or the other should not be seen as limiting unless otherwise specifically noted.

DAF streams are currently largely treated as waste from processing factories since these streams often contain high water volumes and contaminants such as clean-in-place (CIP) fluids, microbes and other low levels of contaminants. These contaminants may make DAF streams unsuitable for human food consumption. This limits the ability to use this waste DAF stream often leading to dumping despite the presence of potentially valuable components in the DAF stream such as protein and fat. Dumping also creates further expense to the processing factories and may be environmentally undesirable as well.

Some attempts have been made to treat DAF streams via centralised processing facilities. Whilst there are efficiencies in use of one large facility to treat significant volumes of DAF stream, the high cost associated with transport of DAF stream waste due to the high-water loading means that centralised facilities are rarely or barely economic. This inefficiency and higher transport cost is of particular concern when the raw DAF streams need to be collected and transported from diversely spread out processing facilities to the centralised DAF processing plant noted above.

A further drawback of art methods that aim to process DAF streams is that the methods typically add compounds such as flocculants and emulsifiers to the raw DAF stream. This is done to assist with separation of components like proteins and fat from the water and other compounds in the raw DAF stream. Use of additional compounds such as flocculants and emulsifiers is however undesirable, particularly at the concentrations required. Additional compounds like flocculants and emulsifiers add to processing expenses and may cause handling issues e.g. excessive foaming or wear/corrosion of processing equipment. A further drawback of flocculants and emulsifiers is that they are not ideal if the final product is to be used in an animal feed since there may be health risks to the animals associated with ingesting the flocculants and emulsifiers used.

Another common characteristic of art DAF stream treatment processes is the use of heating. Heat in itself is not problematic at least to some extent however, art processes tend to heat DAF streams well beyond the DAF stream boiling point. This high level of heat used may have a significant impact on the energy costs of processing the DAF streams and make art processes less economic. Another problem of heating equal to or above boiling point is that increased hazard risk and steam management. High levels of heating beyond the boiling point may also have the potential to compromise the bioactivity / bioavailability of compounds in the DAF stream such as protein denaturing. Protein compounds in particular represent a high proportion of the value of a DAF stream hence it is not ideal to potentially degrade such compounds during processing.

Protein degradation can be reduced by drying at a lower temperature by using a vacuum dryer and therefore, vacuum drying of food streams is not unusual in the art. However, this technique has not, in the inventor's experience, been employed with art DAF stream processes perhaps due to the high water content making vacuum drying uneconomic. In addition, the high protein and fat content of the solid matter in a DAF stream are difficult to manage in a vacuum dryer as during drying the mix may tend to agglomerate and form a bolus or mass causing blocking of machinery, slow or uneven drying, clumping and other handling issues.

Despite the above, there is a growing need to minimise waste from processing operations for environmental reasons, and also to optimise plant efficiency and operations or at least provide the public with a choice.

Further aspects and advantages of the DAF stream and DAF-like stream processes and products and the vacuum dryer and an animal feed ingredient will become apparent from the ensuing description that is given by way of example only.

SUMMARY

A method of producing a non-aqueous DAF product, a free fat composition and protein complex from a raw DAF or DAF-like stream and products therefrom are described. DAF or DAF-like stream processing plants and an associated vacuum dryer are also described along with an animal feed ingredient.

In a first aspect, there is provided a method of producing a substantially non-aqueous DAF product from a raw DAF stream comprising: heating a raw DAF stream and allowing fractionation to occur to produce a fractionated heated DAF stream; separating the fractionated heated DAF stream into a sludge solid fraction and fat fraction from a separated predominantly water fraction; and vacuum drying the separated sludge solid fraction and fat fraction to form the non-aqueous DAF product.

In a second aspect, there is provided a method of producing a substantially non-aqueous DAF product from a raw DAF-like stream comprising: mincing or otherwise reducing a particle size of a raw DAF-like stream to produce a reduced particle size stream and storing the reduced particle size stream for at least 10 minutes; and vacuum drying the reduced particle size stream to form the non-aqueous DAF product.

The non-aqueous DAF product may under go a further separation step to separate free fat and protein in the non-aqueous DAF product, forming a free fat composition and separate protein complex.

In a third aspect, there is provided a substantially non-aqueous DAF product manufactured from a raw DAF or DAF-like stream via the method substantially as described above, the substantially non-aqueous DAF product characterised by being a mixture of a protein complex and free fat composition.

In a fourth aspect, there is provided a free fat composition and separate protein complex manufactured from a raw DAF or DAF-like stream via the method substantially as described above, with the additional step of separating free fat and protein in the non-aqueous DAF product, to form the free fat composition and the separate protein complex.

The free fat composition may be characterised by being substantially anhydrous. The free fat composition may be further characterised by having one or more of the following characteristics: a moisture level less than 0.2%; a water activity less than 0.6; a peroxide value less than 4.2 mEq/kg; a hexanal value less than 1 ppm after 4 months; and/or a decadienol reading less than 15 ppm after 4 months.

The protein complex may be characterised by comprising (when separated from any free fat composition): a particle/granule size of approximately 0.01 to 10mm; and

30-45% fat, 50-65% protein; and a water activity less than 0.6.

In a fifth aspect, there is provided a DAF stream processing plant comprising: a heating and separation unit configured to receive and heat a raw DAF stream and in which separation occurs between a sludge solid fraction, a fat fraction and a predominantly water fraction; a vacuum dryer configured to dry the sludge solid fraction and/or fat fraction; and wherein the DAF stream processing plant is mobile and moved to or near a raw DAF stream producing site for DAF stream processing.

In a sixth aspect, there is provided a DAF-like stream processing plant comprising: a storage vessel for a raw DAF-like stream, the raw DAF-like stream having been minced or otherwise reduced in particle size; a vacuum dryer configured to dry the reduced particle size raw DAF-like stream; and wherein the DAF-like stream processing plant is mobile and moved to or near a raw DAF- like stream producing site for DAF-like stream processing.

In a seventh aspect, there is provided a vacuum dryer comprising: a material drying interior configured to attain and hold a vacuum pressure of less than 1 atmosphere; and a dryer body or dryer interior that moves during drying of a material therein to cause movement of the material being dried during a drying operation.

The method described may be characterised by not requiring the use of additives. For example, unlike art processes, flocculants or emulsifiers are optionally not added to the DAF or DAF-like stream or at any other part of the process. This reduces processing costs, avoids unwanted handling issues and avoids having any unwanted compounds present in the final product meaning the final product is well suited to animal feed applications.

Also, no boiling occurs at atmospheric pressure and hence energy requirements for the process may be lower than might be the case for art methods. Steam or other heat sources are not added directly to the DAF stream hence avoiding a possible contamination source. The volume of steam and in turn heat required during processing may also be minimised by the above process compared to art methods, particularly through use of a vacuum to reduce the temperature at which any water present boils. Further, the lower heat and potentially faster processing time/vacuum pressure may also act to reduce loss of bioactivity / bioavailability of compounds in the final product.

A yet further advantage is that the method of production may act to standardise the final product components.

BRIEF DESCRIPTION OF THE DRAWINGS

Further aspects of DAF stream and DAF-like stream processes and products and the vacuum dryer and an animal feed ingredient will become apparent from the following description that is given by way of example and with reference to the accompanying drawings in which:

Figure 1 illustrates a perspective view from one side of one example of a modular DAF stream processing plant;

Figure 2 illustrates a front elevation view of one example of a modular DAF stream processing plant;

Figure 3 illustrates a detail front elevation view of one example of two vacuum dryers used in the described DAF stream processing plant;

Figure 4 illustrates a detail perspective view from above and to one side of one example of two vacuum dryers used in the described DAF stream processing plant;

Figure 5 illustrates a detail end view of one example of two vacuum dryers used in the described DAF stream processing plant;

Figure 6 illustrates a first example of a process flow diagram for a processing method;

Figure 7 illustrates a second example of a process flow diagram for a processing method;

Figure 8 illustrates a graph showing how the process standardises varying inlet material concentrations in this example comparing the raw DAF stream fat content relative to the final product fat content.

DETAILED DESCRIPTION

As noted above, a method of producing a non-aqueous DAF product, free fat composition, and protein complex from a raw DAF stream and products therefrom are described. Processing of DAF-like streams such as DAF-like streams comprising offal, bone meal, meat, or fish/marine origin materials are also described. DAF or DAF-like stream processing plants and an associated vacuum dryer are also described along with an animal feed ingredient.

For the purposes of this specification, the term 'about' or 'approximately' and grammatical variations thereof mean a quantity, level, degree, value, number, frequency, percentage, dimension, size, amount, weight or length that varies by as much as 30, 25, 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1% to a reference quantity, level, degree, value, number, frequency, percentage, dimension, size, amount, weight or length.

The term 'substantially' or grammatical variations thereof refers to at least about 50%, for example 75%, 85%, 95% or 98%.

The term 'comprise ¹ and grammatical variations thereof shall have an inclusive meaning - i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements.

Methods of Production

In a first aspect, there is provided a method of producing a substantially non-aqueous DAF product from a raw DAF stream comprising: heating a raw DAF stream and allowing fractionation to occur to produce a fractionated heated DAF stream; and separating the fractionated heated DAF stream into a separated sludge solid fraction and fat fraction from a separated predominantly water fraction; and vacuum drying the separated sludge solid fraction and fat fraction to form the non-aqueous DAF product.

In a second aspect, there is provided a method of producing a substantially non-aqueous DAF product from a raw DAF-like stream comprising: mincing or otherwise reducing a particle size of a raw DAF-like stream to produce a reduced particle size stream and storing the reduced particle size stream for at least 10 minutes; and vacuum drying the reduced particle size stream to form the non-aqueous DAF product.

Raw DAF Stream

Based on the inventor's experience, the raw DAF stream may comprise approximately 10-20% by weight of a fat/protein/ash and approximately 80-90% by weight water. In one example the raw DAF stream may comprise approximately 15-20% by weight of a fat/protein/ash and approximately 80-85% by weight water.

On a dry basis, the fat/protein/ash of a typical raw DAF stream may comprise 45-90% by weight fat, 7- 50% by weight protein, and 1-4% by weight ash.

The raw DAF stream may contain clean in place (CIP) compounds including acids (inorganic or organic) and caustic soda.

The raw DAF stream may have a pH equal to or less than 4.6. This may be a standard pH in food applications to halt and prevent microbial growth. Prior to DAF stream treatment via the methods described herein, the pH of a raw DAF stream may be lowered to 4.6 or lower should the raw stream be above this level. This may be completed via known techniques using acids and/or buffer solutions. Similarly, if during performance of the methods described herein, the pH were to rise above 4.6, acid/buffer addition may be completed to the processing stream(s) to maintain a food safe pH level.

The raw DAF stream may be sourced from a dairy factory, a rendering factory, an abattoir or a fish/marine processing factory or facility.

Raw DAF-like Stream

The term 'DAF-like' is used herein to refer to streams with similar compositions (especially water, fat and protein) as DAF streams. Examples of DAF-like streams may be those from abattoirs comprising organs/offal or bone meal, or meat. DAF-like streams may also result from fish/marine material processing.

A DAF-like stream may for example, on a wet basis, comprise 20-35% dry matter, 7-25% protein, and 2- 18% fat. A DAF-like stream such as bone meal for example, on a wet basis, may comprise 55-80% dry matter, 32-33% protein, 1-30% fat and 28-55% ash.

As noted above, fat or water may be added to the DAF-like stream should this be necessary to better replicate the method of processing DAF streams.

The raw DAF-like stream may have a pH equal to or less than 4.6 or a pH adjusted to this level prior to processing the DAF-like stream as described herein. This may be completed via known techniques using acids and/or buffer solutions. Similarly, if during performance of the methods described herein, the pH were to rise above 4.6, acid/buffer addition may be completed to the processing stream(s) to maintain a food safe pH level.

Heating

Heating of the DAF stream may be to a point below the DAF stream boiling point. Typically a DAF stream boiling point may be around that of water i.e. 100°C at atmospheric pressure however, some variation to this boiling point may result from the presence of other compounds in the DAF stream.

In one example, the raw DAF stream may be heated to approximately 65-80°C, or 70-75°C, or 72-75°C. In one example, the heated DAF stream may be held in a heated state for at least 10 minutes. In a further example, the heated DAF stream may be held in a heated state for at least 10, or 15, or 20, or 25, or 30, or 35, or 40, or 45, or 50, or 55, or 60 minutes, or between 1-5 hours, or between 1-6, or 1-5, or 1- 4, or 2-4 hours. This extent of heating may be better suited to the first aspect method described above.

In an alternative example, heating may be restricted to a lower level e.g. 25-45C°, or 30-40°C. This extent of heating may be better suited to the second aspect method described above.

The DAF-like stream may be heated as above in a similar manner.

Separation

Separation as described above may occur via gravity. For example, the residence time during heating of at least 10 minutes or more may result in separation of different fractions by gravity. Other methods could be used to cause or urge separation however gravity separation provides a simple low interference and low cost processing option. In the inventor's experience the separated fractions comprise an upper fat fraction, a mid-layer comprising a water fraction and a base layer comprising a solid/semi-solid fraction. This may be an emulsion in one example but may also be predominantly fat or water and hence not always an emulsion with an even mix of both phases.

The fat may float nearer to the top of the separation vessel. In one example, the fat may comprise a mixture of water, free fat and protein bound to fat all mixed together as an emulsion. The fat content of the fat may be at least approximately 90% fat by weight.

The mid-layer may comprise a water fraction may comprise greater than 95% by weight water. The water fraction may comprise at least 95, or 96, or 97, or 98, or 99% water by weight.

The lower solid/semi-solid fraction (also termed herein as a 'sludge solid fraction') may comprise approximately 20-30%, or 24-28%, or 26-27% by weight solids. The fat and/or sludge solid fraction may contain more than 50% by weight protein and fat compounds.

Part of the separated predominantly water fraction may be recycled with the raw DAF stream. In this case, part may refer to around 5-15% by weight of the water fraction collected being recycled, the rest being discarded. The recycled water fraction may then be heated again to cause further separation and collection of any residual protein/fat content.

Fat Addition

Fat may be added to the raw DAF or DAF-like stream. Fat may be added to the raw DAF stream or raw DAF-like stream, to the heated DAF stream and/or to the fraction(s) described above prior to drying.

The fat added may be from a separate source or may be recycled from the separated heated DAF stream. Where a separate fat source is used, the sourced fat or fat compounds may have a carbon chain length predominantly of a Cis to Cis chain length. The use of a separate fat source may be useful during processing start up in order to help standardise the fat content at least to some extent in the raw DAF or DAF-like stream to be processed. As processing progresses the use of a separate source may no longer be required, for example due the recycled fat stream being sufficient to help standardise the process. The DAF or DAF-like stream itself may have an optimum fat content as well either at the very start of processing or as processing progresses hence limiting or eliminating the requirement for a separate source. As may be appreciated, fat sources of this carbon chain length are inexpensive and usually easily obtained and usually food safe hence easily integrated into the process if required without cause for concern about processing efficiency or end product characteristics.

In one example, fat may be added sufficient to have a fat content in the raw DAF stream or raw DAF-like stream of between 50-70% or 55-65%, or approximately 60% by weight on a dry matter basis. Simple variations in process parameters and conditions may cater for alternative fat concentrations and hence these figures are provided by way of example only.

The addition of fat may be useful to assist with drying. As will be described in more detail below, drying of a DAF sludge solid fraction (comprising fat) may be complicated by clumping and/or bolus formation during drying leading to non-homogenous drying. Through the addition of extra fat, this problem may be avoided as the higher concentration of fat results in a more mobile or pourable non-aqueous DAF product than might be the case were free fat not added. The extent to which additional fat is helpful may depend on the fat content of the fractionated stream(s) to be dried, the design of the dryer itself, and conditions used for drying.

Further Processing Steps

As noted above, the raw DAF-like stream may optionally be minced or otherwise broken down into a smaller size or smaller particle size. The term 'mincing' is used hereafter for ease of reference but this may encompass other methods of reducing the raw stream particle size e.g. cutting, maceration etc. Mincing may be a useful method of standardising DAF-like stream size, increasing the surface area of the raw material and optionally to release any retained water. Using offal as an example of the raw DAF-like stream, the offal may be minced to a uniform size, mincing in turn breaking down the offal and potentially releasing retained water in the organs.

During storage and fractionation noted above, the mixture may be agitated or mixed.

Enzyme digestion may also occur before or during storage of the raw DAF-like stream. Enzyme digestion may be useful to breakdown the raw DAF-like stream in a way that then optimises the final product or protein complex. The enzymes used may be selected from lipases, proteases or amylases.

Optionally, water may be added to the raw DAF-like stream. Typically, this might be done to raise or maintain the temperature of a raw DAF-like stream usually before or during storage and/or to create an optimum water to solids ratio prior to drying. Vacuum Drying

Vacuum drying as noted may occur at a pressure of 0.05-0.2bar or at 0.05, or 0.06, or 0.07, or 0.08, or 0.09, or 0.1, or 0.11, or 0.12, or 0.13, or 0.14, or 0.15, or 0.16, or 0.17, or 0.18, or 0.19, or 0.2bar. In one example vacuum drying may occur at a pressure of approximately O.lbar.

Vacuum drying may take place for 1 to 12, or 3 to 6 hours.

In one example, sufficient heat may be applied during vacuum drying to the separated sludge solid fraction and fat fraction to cause the separated sludge solid fraction and fat fraction to heat to a temperature equal to or above the boiling point of water at the respective vacuum. Per normal laws of thermodynamics, the boiling point of water will reduce from 100°C at atmospheric pressure to as low or lower than 45°C based on the inventor's experience when under vacuum. In one example the dryer contents may heat to a temperature in the range of 40-85°C whilst under vacuum although this temperature may vary considerably dependent on the material density, moisture content, pressure used, heat source temperature used and so on.

The heat source used during vacuum drying may in one example be sourced from a processing plant nearby the DAF processing plant. Examples of heat sources common about processing plants that produce waste DAF streams are heat sources such as steam lines, hot water lines or other already heated processing streams. In this example, the vacuum dryer essentially acts as one side of a heat exchanger cooling another heat source stream.

Heating of the contents inside the dryer may be caused by heat transfer through conduction and/or convection. Heating of the dryer contents may occur indirectly - that is, the heat source does not directly touch or interact with the dryer contents.

The dryer contents may remain within the dryer and under vacuum for sufficient time to reduce the water activity of the dryer contents to below 0.6. Alternatively, drying may be complete when the separated sludge solid fraction and fat fraction or non-aqueous DAF product have a water activity below 0.6. In practice, the water activity achieved using the methods and apparatus described may be equal to or lower than 0.5, or 0.4, or 0.3.

Once the desired water activity of the contents is reached, the vacuum may be released and the resulting dry product removed from the dryer.

Free fat remaining in the final product may be removed, for example by vacuum filtration of the final product.

Fat and Protein Separation

Optionally, the non-aqueous DAF product may undergo a further separation step to separate free fat and protein in the non-aqueous DAF product, forming a free fat composition and separate protein complex. The term 'protein complex' and grammatical variations thereof as used herein refers to protein compounds alone and protein compounds chemically or physically linked to fat compounds. The protein complex may exclude free fats not associated with protein compounds.

The free fat composition may be removed from the non-aqueous DAF product using a vacuum filter. This may be useful for certain further applications for the resulting protein complex.

The protein complex may comprise protein compounds bound to fat compounds. These fat compounds may not be free fats that separate to the free fat composition.

The protein complex may be characterised by having (when separated from any free fat composition): a particle/granule size of approximately 0.01 to 10mm; and

30-45% fat, 50-65% protein; and a water activity less than 0.6.

The fat content may be from 30-45, or 35-45, or 40-45% by weight in the protein complex.

The protein content may be 50-65, or 50-60, or 50-55% by weight in the protein complex.

The protein complex when separated from the free fat composition may be a flowing powder. Flowing in the context of the powder noted may be akin to the way raw sugar particles flow when poured from a container.

The free fat composition may comprise a substantially pure anhydrous fat product. This anhydrous fat product may be very stable.

Further characteristics of the free fat composition may be selected from one or more of the following characteristics: a moisture level less than 0.2%; a water activity less than 0.6; a peroxide value less than 4.2 mEq/kg; a hexanal value less than 1 ppm after 4 months; and/or a decadienol reading less than 15 ppm after 4 months.

Particle Size

The protein complex when separated from the free fat composition may be a flowing powder or flowing granules which may in one example have a particle size of approximately 0.01 to 10mm. The particle size may be 10-500 micron and resemble a powder in form. The particle size may be from 1mm to 10mm and resemble granules in form. The inventor has found that no milling is required post drying and separation to achieve this particle/granule size. The final protein complex inherently has this particle/granule distribution once the moisture is removed and free fat composition separated. The final size distribution of the protein complex may be related to the raw material used. Raw DAF streams that are processed may tend to form finer particle distributions. Raw DAF-like streams such as offal may tend to form larger granules. Milling of the protein complex may be completed irrespective of final inherent particle/granule size should a uniform and particular size be required.

A Non-aqueous DAF Product

In a third aspect, there is provided a substantially non-aqueous DAF product manufactured from a raw DAF stream via the method substantially as described above, the substantially non-aqueous DAF product characterised by being a mixture of a protein complex and free fat composition.

A Separated Free Fat Composition and Protein Complex

In a fourth aspect, there is provided a free fat composition and separate protein complex manufactured from a raw DAF or DAF-like stream via the method substantially as described above, with the additional step of separating free fat and protein in the non-aqueous DAF product, to form the free fat composition and the separate protein complex.

Separated Protein Complex

The separated protein complex may substantially comprise: a particle/granule size of approximately 0.01 to 10mm;

30-45% fat, 50-65% protein; and a water activity less than 0.6.

In one example, the separated protein complex may substantially comprise 30-45% fat and 50-65% protein. The remainder of this separated protein complex may comprise ash and water. This fat/protein content and ratio in the separated protein complex was found to be unexpectedly consistent post processing despite varying raw DAF or DAF-like stream fat/protein content.

Separated Free Fat Composition

The separated free fat composition may comprise a substantially pure anhydrous fat product. This fat product may be very stable.

Further characteristics of the free fat composition may comprise: a moisture level less than 0.2%; a water activity less than 0.6; a peroxide value less than 4.2 mEq/kg; a hexanal value less than 1 ppm after 4 months; and/or a decadienol reading less than 15 ppm after 4 months.

Pourable

The non-aqueous DAF product noted above may be pourable. The word 'pourable' or grammatical variations thereof in the above context refers to the non-aqueous DAF product moving freely when subjected to a shear force undergoing pouring behaviour akin to how melted butter would pour or flow when poured from a bowl or container. Flowing may be in a Newtonian manner.

Water Activity

The water activity of the non-aqueous DAF product, or free fat composition, or protein complex may be at or less than 0.6. In practice, the inventor has found that the water activity may be lower than or equal to 0.5, or 0.4, or 0.3. As may be appreciated, this low water activity is well below levels that might support microbial growth hence the final product is very stable when stored in a sealed container even under ambient temperature and pressure.

Fatty Acid Profile

Assuming no additional fat is added to the process, the fatty acid profile of the non-aqueous DAF product may be proportional to the raw DAF or DAF-like stream fatty acid profile e.g. the fatty acid profile of the non-aqueous DAF product may be proportional to the fatty acid profile of a dairy DAF stream assuming the raw DAF stream is from a dairy factory. As may be appreciated, the addition of other fat material to the process may have an impact on the final fatty acid profile of the non-aqueous DAF product.

Protein Type

The predominant proteins in the protein complex may be proportional to the raw DAF or DAF-like stream predominant proteins. For example, in a raw dairy DAF stream the predominant protein would likely be casein, this being the predominant protein in a raw dairy DAF stream. Hygroscopic / Hydrophobic Nature

In the inventor's experience, the protein complex once separated from the free fat composition in the non-aqueous DAF product is neither particularly hygroscopic nor hydrophobic. The extent of hygroscopic or hydrophobic properties of the protein complex once separated from free fat composition may be akin to whole milk powder albeit with a somewhat coarser particle size distribution. This relatively stable nature in terms of hygroscopic and hydrophobic properties may be helpful from a storage perspective as no special handling conditions are needed bar typical methods e.g. storage in a sealed bag or container.

Stability

Aside from low water activity and hence low likelihood of microbial growth, the non-aqueous DAF product, free fat composition or protein complex have a very high stability, i.e. similar to that observed for dried milk powder. For example, stability as measured via other factors such as separation, resistance to temperature variations, maintenance of flowability and so on remain the same as the original product even after storage for 3 months (or well longer as envisaged by the inventor).

Absence of Lactose

One further characteristic of the non-aqueous DAF product or protein complex where a dairy DAF stream is used is that lactose is not present. Lactose is a milk sugar present in many dairy products. The absence of lactose in the non-aqueous DAF product or protein complex may be an advantage for some final food ingredient uses where lactose intolerance is a concern.

Animal Supplement or Animal Feed

The non-aqueous DAF product, or protein complex, or free fat composition produced from the DAF or DAF-like stream may be an animal feed supplement in itself or an ingredient in a formulated animal feed. Supplements may for example be food treats for animals. One specific example may be a food treat such as a dosed amount of roll or lozenge fed to an animal in conjunction with a normal diet. The nature of the protein and/or fat content may be such that the supplement is highly desirable to certain types of animal. Animal feeds may be more complex and formulated to provide a full balance of nutrients to an animal, the products described herein forming one part of the wider formulation e.g. a portion or all of the protein content for a meal.

Animals envisaged for these end products, be they supplements or animal feed products, may be selected from livestock or companion animals. The animals may be of porcine, bovine, cervine, or ovine origin. The animals may be pigs, calves/cattle/cows, deer or lambs/sheep. Companion animals may include those of canine or feline origin including domestic dogs and cats. Further animals to which the supplement or animal feed may be useful for include horses and farmed fish feeds e.g. as part of a salmon farm feed supplement or formulation. This application may be a useful and valuable protein and/or fat source for animals and comparatively inexpensive given that the raw material may be a waste stream.

DAF Stream Processing Plant

In a fifth aspect, there is provided a DAF stream processing plant comprising: a heating and separation unit configured to receive and heat a raw DAF or DAF-like stream and in which separation occurs between a sludge solid fraction, a fat fraction and a predominantly water fraction; a vacuum dryer configured to dry the sludge solid fraction and/or fat fraction; and wherein the DAF stream processing plant is mobile and moved to or near a raw DAF or DAF-like stream producing site for DAF or DAF-like stream processing.

DAF-Like Stream Processing Plant

In a sixth aspect, there is provided a DAF-like stream processing plant comprising: a storage vessel configured to store a raw DAF-like stream, the raw DAF-like stream having been minced or otherwise reduced in particle size to a reduced particle size raw DAF-like stream; a vacuum dryer configured to dry the reduced particle size raw DAF-like stream; and wherein the DAF-like stream processing plant is mobile and moved to or near a raw DAF-like stream producing site for DAF-like stream processing.

Use and Mobility

The DAF or DAF-like stream processing plants may be located during DAF or DAF-like stream processing about or near a raw DAF or DAF-like stream source. For example, the plant as noted above may be mobile and temporarily or permanently installed adjacent or near a raw DAF or DAF-like stream source such as a dairy factory, a rendering factory, or an abattoir or offal or fish/marine producing factory. Placement of the plant near a raw DAF or DAF-like stream source may eliminate or at least minimise transport costs associated with moving raw DAF or DAF-like streams (mainly water). This may make the plant described far more cost effective than art centralised installations.

The DAF or DAF-like stream processing plant may be manufactured in modules, the modules being linked together to form the DAF or DAF-like stream processing plant. For example, the plant may be installed on platforms (modules), the separate platforms and parts being linked together onsite to form the overall DAF or DAF-like stream processing plant. Different platforms/modules may comprise different parts of the process e.g. heating, separation and drying operations. This modular design may be useful to increase the mobility of the DAF or DAF-like stream processing plant and allow it to easily be installed and uninstalled and the plant moved between locations and/or positioned in different configurations to suit a land area available for the plant. Assuming each module is designed appropriately, it is the inventor's experience that the modules may be transported on a truck between locations. A truck bed in this example may define the ideal footprint of each module.

In one example, the plant or modules positioned together to form a plant may have a comparatively small footprint. For example, each module in one example may fit within the footprint of a 40-foot shipping container and a total of two 40 foot containers stacked on each other may be sufficient footprint area for the plant as a whole. A processing plant of this nature and size may, in the inventor's experience, process a volume of DAF or DAF-like stream product of around 5-15m ³ per day. As should be appreciated this style of design and the figures noted are provided by way of example only for context and should not be seen as limiting.

The DAF or DAF-like stream processing plant may comprise multiple heating and separation units. The DAF or DAF-like stream processing plant may comprise multiple vacuum drying units.

Vacuum Dryer

In a seventh aspect, there is provided a vacuum dryer comprising: a material drying interior configured to attain and hold a vacuum pressure of less than 1 atmosphere; and a dryer body or dryer interior configured to move during drying of a material therein configured to cause movement of material to be dried in the dryer during a drying operation.

Vacuum Pressure

The vacuum dryer material drying interior may be configured to attain and hold a vacuum pressure of: 0.05-0.2bar or approximately 0.05, or 0.06, or 0.07, or 0.08, or 0.09, or 0.1, or 0.11, or 0.12, or 0.13, or 0.14, or 0.15, or 0.16, or 0.17, or 0.18, or 0.19, or 0.2bar. In one example, the vacuum dryer may attain and hold a pressure of approximately O.lbar.

A vacuum of this nature may be achieved via known means such as through use of one or more sealed chambers (dryer interior), the sealed chambers in communication with at least one evacuation pump drawing air from the chamber(s). Reference to this means of achieving a vacuum should not be seen as limiting as other methods may be used. Movement during Drying

The vacuum dryer body or vacuum dryer interior may move during drying as noted above.

Movement of the vacuum dryer body or vacuum dryer interior may be configured so that material to be dried in the dryer moves about a vertical plane by approximately 1-15 degrees, or 2-10 degrees.

Movement may be in a rocking manner back and forth about a vertical plane. The dryer or dryer interior may rock about a pivot point. The pivot point may be located at a dryer or dryer interior centre point. Alternatively, the pivot point may be located at an end or intermediate point along the dryer or dryer interior length or width.

Alternatively, the dryer body or dryer interior may move rotationally during drying. For example, the dryer or dryer interior may rotate about a horizontally aligned axis (or axis offset from a horizontal plane). In this case the same function may be achieved of material within the dryer interior being moved about during drying.

Movement of the material being dried was found by the inventor to be an important aspect of correct drying operation. The material being dried may have significant fat and protein concentrations and these compounds may inherently can become sticky or bind together. In worst circumstances, the mixture may clump together to form a bolus during drying and prevent the bolus interior from drying i.e. uneven or poor drying results. Removal of the bolus formed from the dryer interior may also be difficult. Movement of the material being dried, even in a relatively gentle manner such as by rocking or rotation noted above, may assist with heat transfer and drying. The final product may be uniformly dry and of a pourable consistency.

Air Pulsing

Air may be pulsed into the vacuum dryer interior during drying. Air pulsing may disturb or move material being dried inside the vacuum dryer interior. Air pulsing may be completed to assist with material movement within the dryer interior. The inventor has found that this may be useful to help urge movement during drying, avoid clumping and encourage even drying.

Whilst reference is made to use of air for the pulsing, other gases may be used that are ideally inert relative to the material being dried.

The term 'pulsing' refers to the air (or other gas) being injected into the dryer interior intermittently and for short time periods. In one example, the inventor found that a dryer comprising 8 tubes may use a total of 10 litres of air pulsed every 5 seconds to the 8 tubes, each pulse may have a duration of approximately 150 milliseconds. As should be appreciated this extent of pulsing and the figures noted are provided by way of example only for context and should not be seen as limiting. Air pulsing may also be completed using one or more directing nozzles that direct the airflow in a manner that urges material within the dryer to move or be transported from a position of settling e.g. directed from the base of the dryer interior upwards or directed from one end of a dryer interior towards an opposing end.

Heat Source

The dryer may comprise a heat source to heat the material drying interior during vacuum drying to a temperature equal to or above the boiling point of water at the vacuum pressure to which the dryer is reduced to. The heat source may be a heated fluid that indirectly transfers heat to the dryer interior or a part thereof. As the dryer interior heats, material in the dryer also heats. The heated fluid may be selected from: hot water, a hot processing liquid or gas stream, or steam. The heated fluid may heat the dryer interior or a part thereof to a temperature above 40°C, or approximately 45-85°C, the exact temperature corresponding to the boiling point of water at the vacuum pressure of the dryer.

Stirrer

The, or each, dryer interior may comprise an agitation means such as a stirrer. The function of an agitation means may be to assist with even heat transfer assuming an indirect heating means is used.

Tubes

In one example, the dryer comprises multiple elongated tubes. The volume inside each elongated tube may be the material dryer interior which is under a vacuum during material drying. The term 'tube' is used for ease of description and which may comprise a generally circular cross-section. Alternate elongated tube shapes may also be used with differing cross-section shapes, e.g. elliptical, square, random curved, polygonal and so on and, reference to the term tube should not be seen as limited to only circular cross-sections. Similarly, the term 'elongated' is used to refer to a generally straight tube of common cross-section and common longitudinal axis. Again, this should not be seen as limiting since the tube may not be straight or have a common longitudinal axis throughout the tube length. Similarly, the tube cross-section may vary along the longitudinal length of the tube as well.

In one example, an elongated tube used in the vacuum dryer may have a diameter of approximately 150- 500, or 200-450, or 200-400, or 200-300, or 250mm. As should be appreciated, the elongated tube diameter may vary depending on the plant or dryer size, volumes processed and other design factors hence these dimensions should not be seen as limiting.

In one example the elongated tube length may be at least 500mm to 5m long, or l-4m long, or l-3m long, or l-2m long, or 2-3m long. Each elongated tube may define a volume of approximately 0.1 to 0.2 m ³ .

Multiple Tubes

As noted above, the vacuum dryer may comprise multiple elongated tubes. A dryer may comprise 2-20 elongated tubes. The vacuum dryer may comprise 2, or 3, or 4, or 5, or 6, or 7, or 8, or 9, or 10, or 11, or 12, or 13, or 14, or 15, or 16, or 17, or 18, or 19, or 20 elongated tubes.

The tubes may be mounted and fixed on a rack or frame so that all tubes are rigidly connected together and collectively form the vacuum dryer. The rack or frame may move and, in doing so, also may move the tubes. The rack or frame may be mounted on a motor or ram that drives the movement described.

The tubes may have individual openings at each tube end for product feed at one end and discharge at the opposing end. Alternatively, product feed and discharge may occur via one or more common points linking to two or more tube openings.

The tubes may be linked either individually, as a set or all collectively to a vacuum pump. The vacuum pump may be located about one end of the tube(s).

Air pulsing if completed may occur about or at a tube exit end.

The tube vacuum may be drawn about a tube inlet end.

Tube Charge and Discharge

The tube or tubes used to form the dryer may be charged or filled partly or fully with material to be dried by pumping the sludge solid fraction into the tubes. As noted above, the sludge solids may comprise 20- 30%, or 24-28% solids on a wet basis. The sludge solid fraction may be substantially protein and fat compounds on a dry matter basis. Given this composition, the sludge solid fraction may be pumped relatively easily.

As noted above, after drying, the non-aqueous DAF product may be pourable. A tube may therefore be discharged or emptied by opening the tube end and tilting the tube about the tube longitudinal axis to cause the dried non-aqueous DAF product to pour from the tube interior.

Advantages

As may be appreciated from the above, the method described may be characterised by not requiring the use of additives. For example, unlike art processes, no flocculants or emulsifiers may be added to the DAF stream or at any other part of the process. This may reduce processing costs, avoid unwanted handling issues such as foaming and may avoid having any unwanted compounds present in the final product. As a result, the final product may be well suited to manufacture and use as an animal supplement or as an ingredient in animal feed applications.

Also, no boiling occurs at atmospheric pressure and hence energy requirements for the process may be lower than might be the case for art methods. Steam or other heat sources may not be added directly to the DAF stream hence avoiding a possible contamination source. The volume of steam, and in turn heat, needed during processing may also be minimised by the above process compared to art methods, particularly through use of a vacuum to reduce the temperature at which any water present boils.

Further, the lower heat and potentially faster processing time/vacuum pressure may also act to reduce loss of the bioactivity / bioavailability of compounds in the final product.

A yet further advantage may be that the method of production may act to standardise the final product components. The inventor unexpectedly found that the process was able to produce a relatively standardised final product from quite variable raw DAF or DAF-like stream compositions. For example, the inlet raw DAF stream fat and water levels and the final non-aqueous DAF product produced by the method provides a consistent (less than 10% variation) final fat and protein content. Inlet concentrations of fat for example that may vary as much as 30% between raw DAF stream sources may after processing via the method described above result in a consistent final fat content with less than 10, or 9, or 8, or 7, or 6, or 5, or 4, or 3, or 2, or 1% variation between batches. This may be a useful advantage in that raw DAF streams inherently comprise varying levels of components such as water, fat and protein and any process that treats such streams needs to be versatile enough to address these variations and still operate consistently. The final end product having very consistent final concentrations was particularly unexpected and a useful benefit of the process as it avoids extra processing and provides consistency of product standard and quality.

The details and examples described above 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, and any or all combinations of any two or more said parts, elements or features.

Further, where specific integers are mentioned herein which have known equivalents in the art to which the details and examples relate, such known equivalents are deemed to be incorporated herein as if individually set forth.

WORKING EXAMPLES

The above described dissolved DAF stream and DAF-like stream processes and products and the vacuum dryer and an animal feed ingredient are now described by reference to specific examples. EXAM PLE 1

An example is shown in Figures 1 and 2 of a modular processing plant. As shown, the DAF stream processing plant generally shown by arrow 1 comprises one heating and two separation chambers 2 and a series of four vacuum dryers 3 in the example shown. Fewer or more chambers 2 may be used. Fewer or more vacuum dryers 3 may be used. The chambers 2 may heat and hold a charge of raw DAF stream.

The raw DAF stream may separate during heating in the chamber into an upper fat fraction, a mid-level water fraction (not shown) and a lower sludge solid fraction (not shown). The sludge solid fraction and a fat fraction may then be pumped to the vacuum dryers 3 and the water fraction may be discarded or a small amount optionally recycled back with raw DAF stream for further processing. In the inventor's experience only approximately 10-15% by weight of the total volume of water fraction might be recycled (or recycling not completed at all).

Alternatively, the chamber 2 may hold the raw DAF stream for a period of time and/or used to complete additional optional processing, for example being hot water addition and/or enzyme addition and digestion. After storage, all of the chamber 2 contents in this example may be transferred to the dryers 3.

The extent of fractionation may be a function of the 'free' water i.e. the amount of extra cellular water present in the raw DAF stream. A raw DAF stream from a dairy factory may be almost entirely made up of extra-cellular water while a raw DAF-like stream comprising offal from an abattoir may comprise a similar degree of water but this is bound up as intracellular water.

As can be seen, the drawings show an example where the DAF stream processing plant is built around two 40 foot shipping containers 4 and 4' stacked on top of each other. Note that the container walls are removed in Figure 1 to view the contents and the upper container 4' is removed completely in Figure 2. The shipping containers 4, 4' form separate modules that together form the DAF stream processing plant 1. One shipping container 4 or 4' effectively presents a footprint for the DAF stream processing plant 1 and this footprint is equivalent to the load space on a truck deck. The DAF stream processing plant 1 is therefore mobile and able to be transported to different sites, in this example via two trucks/truck loads. Smaller designs may fit into two 20 foot containers for example and be transportable on a single truck/truckload. Larger DAF stream processing plants may use two sets or more containers.

Figures 3 to 5 illustrate two vacuum dryers 3 in more detail. The vacuum dryers indicated generally by arrow 3 comprise a frame 5 that acts to hold a series of tubes 6 in place. In the example shown in Figures 3-5, two dryers 3 are shown mounted side by side, each dryer 3 comprising a frame 5 and a total of eight tubes each. The vacuum dryers 3 pivot up and down about a vertical plane the movement direction indicated by arrow 7 about pivot point 8. Movement occurs during drying to avoid clumping or bolus formation inside the tubes 6 of dried material (not shown). The tubes 6 comprise one end 9 for material charging and an opposing end for discharging 10. Vacuum pump evacuation may also occur about the inlet end 9 of the tubes 6. In the example shown, each tube 6 has an individual charging and discharging opening while all of the tubes 6 have a common link to the vacuum pump. The tubes 6 may comprise air injection inlets (not shown) that allow for the pulsing of air into the tubes during drying.

EXAMPLE 2

One example of the way the process works is described below and with reference to the flow diagram shown in Figure 6. This process may be suited to a raw DAF stream from a dairy factory.

1. Locate the DAF stream processing plant by a DAF stream processing factory such as a dairy factory and provide a raw DAF stream to the DAF stream processing plant.

2. Heat the raw DAF stream to a temperature of 65-80°C and pump the heated raw DAF stream to a separation vessel.

3. Optionally, add fat as required to attain a desired raw DAF stream fat concentration of 50-70% by weight.

4. Hold the heated DAF stream in the separation vessel for 1-4 hours with the heated DAF stream at a temperature of 65-80°C.

5. Once three fractions result, separate the sludge solid fraction (20-30% solids by weight) from the base of the vessel and the floating fat from the top of the vessel from the water mid-level fraction.

6. Optionally, recycle some of the water fraction (typically 10-15% by weight) with further raw DAF stream for a further heating and separation step.

7. Pump the separated sludge solid and fat as a mixture into the dryer tubes.

8. Seal and evacuate the tubes using a vacuum pump to a pressure of 0.05-0.2bar, optionally commence tube heating so that the tube interior temperature and/or material in the tube reaches a temperature equal to or above the boiling point of water at the vacuum pressure at which the dryer operates.

9. Commence dryer movement using the ram and pivot which rocks the tubes up and down.

10. Optionally, pulse air into the dryer during drying.

11. Continue vacuum drying until the water activity of the sludge solid fraction reaches 0.6 or below.

12. Unseal the tubes and remove the dried pourable non-aqueous DAF product from the tubes.

13. Optionally, separate the free fat composition (circle 14) from the protein complex (circle 13) in the pourable non-aqueous DAF product to form a powdered protein complex. This may be completed using a vacuum filter. EXAMPLE 3

An alternative example of the way the process works is described below and with reference to the flow diagram shown in Figure 7. This process may be suited to a raw DAF or DAF-like stream comprising offal or bone meal, or meat.

1. Locate the DAF stream processing plant by a DAF-like processing factory such as an abattoir and provide a raw DAF-like stream comprising offal to the DAF-like processing plant.

2. Optionally mince the offal.

3. Optionally add acid to the offal.

4. Collect the offal in a storage vessel and maintain the offal at or around body temperature (30- 40°C) during storage.

5. Optionally add hot water to the stored offal.

6. Optionally add enzyme to the stored offal. This may be in the form of a kiwifruit pulp.

7. Optionally, add fat as required to attain a desired fat concentration of 50-70% by weight.

8. Transfer the stored offal into the dryer tubes.

9. Seal and evacuate the tubes using a vacuum pump to a pressure of 0.05-0.2bar, optionally commence tube heating so that the tube interior temperature and/or material in the tube reaches a temperature equal to or above the boiling point of water at the vacuum pressure at which the dryer operates.

10. Commence dryer movement using the ram and pivot which rocks the tubes up and down.

11. Optionally, pulse air into the dryer during drying.

12. Continue vacuum drying until the water activity of the sludge solid fraction reaches 0.6 or below.

13. Unseal the tubes and remove the dried pourable non-aqueous DAF product from the tubes.

14. Optionally, separate the free fat composition (circle 14) from the protein complex (circle 13) in the pourable non-aqueous DAF product to form a powdered protein complex. This may be completed using a vacuum filter.

EXAMPLE 4

As noted above, one of the advantages of the process is that it can take as a feed a varied DAF stream composition and provide a relatively standardised final product.

Figure 8 illustrates this aspect, in this example focussing on the fat content. Multiple processing runs were completed using the above described DAF stream processing plant using different raw DAF streams. The fat content was measured in both the raw DAF stream and the non-aqueous DAF product produced by the DAF stream processing plant. As can be seen from the graph in Figure 8, the raw DAF stream fat content was quite variable ranging from around 55 to 75% by weight on a dry basis in the seven different raw DAF streams processed. By contrast the fat content in the resulting non-aqueous DAF product was highly consistent at around 45% by weight on a dry matter basis plus or minus only 2-3% between the seven final products. These findings were unexpected as greater variation was anticipated based on raw DAF stream contents. The process is able to standardise key aspects of the flowable product despite variation at entry leading to a useful additional characteristic of the product produced from the DAF stream processing plant particularly when the product is to be used in formulation of subsequent products where standardisation is desirable. Aspects of the DAF stream and DAF-like stream processes and products and the vacuum dryer and an animal feed ingredient have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope of the claims herein.