The present invention relates to a milk-alternative product and a method for producing a milk-alternative product. The invention is particularly, but not exclusively, concerned with a milk-alternative product in which a portion of the oil phase is replaced by alternative substances, and more particularly a product in which the mechanical properties of normal milk are generally retained.

Milk is a common food product, and is essentially an oil- in-water emulsion. This means that it has a continuous aqueous phase into which an oil phase is dispersed. In natural milk, the oil phase consists of a large number of dispersed fat droplets whilst the aqueous phase generally also contains proteins, carbohydrates, vitamins and other minor ingredients.

Many food products on the market are milk-based, for example creams, cheeses and dairy spreads. However, natural milk, and therefore any products made from it, is generally high in fat content, and in particular high in saturated fat content.

It is well established that ingestion of saturated fat can increase blood plasma total cholesterol concentration, and that this concentration is correlated with the extent of atherosclerosis and the incidence of coronary heart disease.

Many people also seek to reduce their total fat intake as part of a balanced and/or healthy diet. Whilst skimming the fat from milk is a well know way of reducing the fat content of milk, it also changes the physical properties of the milk, and of any product or foodstuff manufactured from the milk, as there are far fewer fat droplets in the emulsion. For example, cheeses made from skimmed milk generally have an identifiable texture or "mouth feel" which is significantly different from cheese made from whole milk.

Various attempts have been made to overcome the above problems by replacing the natural or bovine fat content of the milk with a vegetable oil. However, in such products a reduced fat content is generally achieved by having a smaller number of oil droplets in the oil phase, or by having oil droplets which are smaller. This results in milk products which have different physical properties and in particular which have a significantly different texture and taste.

The present invention seeks to provide a milk-alternative product which has a lower total fat content whilst retaining many, most or all of the physical properties of natural milk. The milk-alternative compositions of the invention can be used in the manufacture of foodstuffs in the same way as natural milk.

The present invention also provides a milk-alternative product which is a carrier for an active compound. The active compound may be delivered to a person or animal through the milk-alternative product or a foodstuff manufactured from it.

A first aspect of the present invention provides a miIk- alternative product which is an emulsion of an oil phase in an aqueous phase, wherein the oil phase comprises a plurality of modified oil droplets, each modified oil droplet having an outer shell of oil and a core of a filler substance.

Preferably the filler substance is aqueous, and in particular embodiments may be entirely water. This allows the modified oil droplets to be approximately the same mass and size as the equivalent oil droplets in natural milk, whilst having a lower fat content. The filler substance may also include an emulsifier or surface active agent. Optionally the emulsifier or surface active agent may itself convey further health benefits on a consumer. For example phospholipids (such as lecithin) are known to enhance mental competence and can also act as emulsifiers.

Preferably the aqueous phase is skimmed milk.

Preferably the oil is a vegetable oil. More preferably the vegetable oil contains a blood cholesterol lowering agent, such as phytosterol, oryzanol, tocopherol, tocotrienol, polyphenol or a mixture of any two or more of the above.

As used herein, the term phytosterol covers the whole group of free phytosterols, phytosterol fatty acid esters and (acylated) phytosterol glucosides. Further description and schematic drawings of phytosterols are given in "Influence of Processing on Sterols of Edible Vegetable Oils", S.P. Kochhar, Prog. Lipid Res. 22: pp. 161-188. Oryzanol consists of a mixture of ferulic acid esters of unsaturated triterpene alcohols and is also referred to as gamma-oryzanol.

The terms tocopherol and tocotrienol are used herein to cover the whole family of molecules, including alpha, beta, gamma and delta tocopherols and tocotrienols. Further description and schematic drawings of oryzanol, tocopherols and tocotrienols are given in "Separation of Vitamin E and gamma-Oryzanols from Rice Bran by Normal- phase Chromatography", M. Diack and M. Saska, JAOCS Vol.71, no.11, p. 1211.

As used herein, the term polyphenols refers to all plant phenolic molecules derived from a plant source with an anti-oxidant activity and not covered by the terms oryzanol, tocotrienol and tocopherol, e.g. simple phenols and phenolic acids, hydroxycinnamic acid derivatives (e.g. coumaric and ferulic acids) and flavonoids.

The vegetable oil may be rice bran oil, wheat germ oil, maize germ oil, oat oil, oat bran oil, sesame seed oil, soybean oil, sheanut oil, palm oil, rape oil or a mixture of any two or more thereof. Preferably the oil may be rice bran oil, wheat germ oil, maize germ oil, oat oil, oat bran oil, sesame seed oil, soybean oil, sheanut oil or a mixture of any two thereof, as these oils all contain significant amounts of naturally-occurring phytosterol. More preferably the vegetable oil is wheat germ oil and/or rice bran oil.

As the modified oil droplets have an outer shell of oil, their physical properties are substantially the same as, or identical to, the equivalent oil droplets in natural milk. The modified oil droplets can also be made the same size as the oil droplets in natural milk, whilst reducing the overall fat content and the overall calorific content of the milk-alternative. Fat droplets in natural milk are commonly in the size range 0.1 to 10 μm. The oil droplets in the milk alternative product are typically 0.05 to 20 μm diameter and preferably 0.1 to 10 μm diameter.

Methods of producing suitable droplets and mixing them with an aqueous phase are described in more detail below.

Thus the milk-alternative product can be used to make milk-based foodstuffs, such as creams, cheeses and yoghurts which have physical properties which are substantially the same as, or identical to, the equivalent products made from natural milk.

The filler substance may alternatively be solid particle which has a low calorific value and is used as a bulking agent. Preferably such a filler substance is made from a material which would otherwise be a waste product of a foodstuff manufacturing process in which the miIk- alternative is used. For example, lactalbumin can be recycled from the whey off-stream in cheese production and used as the filler substance.

In a development of this aspect, the filler substance includes one or more active compounds. This development allows the milk-alternative product or a foodstuff made from that product to be used to deliver the active compound(s) to the consumer.

The filler substance may be aqueous and further contain an ingredient which is reactive to one or more ingredients contained in the aqueous phase of the milk- alternative product. For example the aqueous filler substance may include an enzyme, such as an enzyme to aid or enhance digestion (e.g. a protease or carbohydrase), that would normally react with components of the aqueous phase such as proteins and carbohydrates. Alternatively an aqueous filler substance may include an enzyme inhibitor, such as an anti-obesity lipase inhibitor, that would interfere with the natural maturation of dairy products made from the milk-alternative product if it were present in the aqueous phase.

In further alternatives, the filler substance may include volatile components, thereby allowing these components to be retained more effectively within the milk-alternative product during further processing such as maturation, heat treatment and storage than if the same components were simply mixed into the outer aqueous phase.

In yet further alternatives the filler substance may include one or more micro-organisms, such as bacteria, yeast or moulds and preferably bacteria that are commonly used in the dairy industry. The growth of these micro¬ organisms can then be controlled as it will only proceed until the nutrients available within the modified oil droplets have been exhausted. Thus the growth of the micro-organisms can be controlled either by control of the size of the modified oil droplets, or by control of the nutrient composition and/or concentration contained in the filler substance. The use of the filler substance also allows a nutrient composition to be included inside the oil droplets, without placing it in the aqueous phase of the milk-alternative product.

Micro-organisms cultivated in this way can be accurately controlled and can be provided in the milk-alternative product, or any foodstuff derived from it, without adversely affecting the aqueous phase of that product, for example by allowing the micro-organisms to grow in the aqueous phase, or by requiring nutrients to be provided in the aqueous phase.

The organisms contained in the filler substance can be chosen to produce a metabolic product which provides a health benefit to a consumer, or which confers improved organoleptic properties on the milk-alternative product.

Examples of micro-organisms that can be used in this way are lactobacilli, which are known to act as pro-biotics and confer benefits on the digestive system.

The filler substance may alternatively or additionally include an active ingredient that is beneficial to the health of the consumer, or which confers a physical benefit on the properties of the milk-alternative product or a foodstuff made from it.

Examples of active ingredients that may be included in this manner include: anti-oxidants (e.g. beta-carotene, polyphenols, alpha-lipoic acid); amino acids; vitamins; folic acid; pantothenic acid; minerals (e.g. selenium, calcium, magnesium, manganese, zinc) ; co-enzymes (e.g. CoA, Coenzyme QlO); glucosamine; chondroitin; and chitosan. The above list is intended to be illustrative of the types of active ingredients which can be included in the filler substance, and the skilled person will appreciate that other active ingredients can also be included.

In particular, the active ingredient may be sensitive to contact with air (for example an ingredient that is easily oxidised) . Examples of such compounds are poly¬ unsaturated omega-3 and omega-6 fatty acids. By containing such compounds inside the oil droplets, their exposure to air can be greatly reduced, or even eliminated prior to the consumption of the milk- alternative product, thereby ensuring their effective delivery to the consumer.

The filler compound may also include one or more pharmaceutically active compounds, thus making the milk- alternative product a useful delivery medium for any such pharmaceutically active compound. Examples of active ingredients that may be included in this manner include: lipase inhibitors, statins, anti-obesity agents.

A second aspect of the present invention provides a method of manufacturing a milk-alternative product, including the steps of:

mixing a filler substance with an oil to form a dispersion of filler droplets; and

mixing said dispersion into an aqueous solution to form an emulsion of oil-wrapped filler droplets in an aqueous continuous phase.

Preferably one or both of the mixing steps are performed by injecting the first mentioned substance into a stream of the second mentioned substance to atomise and disperse the first mentioned substance. This can allow a fine dispersion to be achieved in both steps without the use of an emulsifier.

A further aspect of the invention provides a milk- alternative product obtained by the process of the previous aspect. Further aspects of the present invention provide methods of delivering an active compound to an animal comprising formulating it in a milk-alternative product and administering the milk-alternative product, or a foodstuff manufactured from said milk-alternative product, to the animal.

A preferred embodiment of the method of the present invention will now be described.

A filled oil is produced by injecting an aqueous solution containing emulsifying agent such as lecithin as an emulsifier into a vegetable oil which in this example is either a refined wheat germ oil or other vegetable oil that has been supplemented with phytosterols, in the temperature range 0 - 1250C. The injection system comprises a 50 mm diameter tube along which the oil passes at a pressure of 1 to 10 bar and a flow rate of 5,000 to 30,000 litres/hour and preferably in the range 10,000 to 20,000 litres/hour. Four, to six injection nozzles of 0.7 mm diameter formed in the wall of the tube allowed the aqueous solution to be radially injected into the oil stream at a pressure in the range of 100 to 500 bar and preferably 200 - 300 bar. The nozzle orifices are covered with brass gauze to prevent any debris from blocking the nozzle exits.

With this system the aqueous solution is injected at between 250 to 10,000 litres/hour and preferably 700 - 1,200 litres/hour, thus producing a filled oil which has a maximum of 95 vol.% fat and typically 25 - 75 vol. % fat. The injection causes the aqueous phase to atomise and form a stable emulsion with a consistent water droplet size of around 0.1 - 10 μm diameter and preferably in the range 1 - 8 μm diameter. Raw milk used to produce the milk-alternative product is stored at less than 60C. The raw milk is preheated to 55°C and introduced into a centrifugal separator which separates the raw milk into 40 vol.% fat cream and 0.05 vol.% skimmed milk.

The filled oil produced by the above injection process is then heated/cooled to 45°C and injected into the skimmed milk (which is now also at 45°C) .

The injection system used for this second injection is essentially identical to that used for the first injection above. The process may be carried out using consecutive injection systems in a single process, or by storing the filled oil after the first injection process and then using it in the second injection process (which may or may not use the same system) .

Thus the skimmed milk is passed along the 50 mm diameter tube at a pressure of 1.5 bar and a flow rate of approximately 21,000 litres an hour. The filled oil is radially injected into the skimmed milk stream at a pressure in the range 200-220 bar.

With this arrangement, the filled oil is injected at between 700 to 1,000 litres per hour, producing a milk- alternative vegetable oil cream product having approximately 17 to 23 vol.% total fat. The injection causes the filled oil to atomise and form a stable emulsion with a consistent oil droplet size of around 0.1 - 10 μm diameter. By injecting the filled oil, the majority of oil droplets in the milk-alternative product will have an outer shell of oil and contain the initially injected aqueous phase as a core filler substance. Incorporation of additional substances (such as active components) in the aqueous phase is carried out using standard mixing processes prior to injection of the aqueous phase into the oil.

It will be appreciated that the above process can be varied depending on the content of the aqueous phase. In particular, the temperature and pressures of the injection processes may be varied depending on the nature of the aqueous phase and particularly of any active ingredient contained therein, for example to prevent denaturing of a protein or micro-organism.

The milk-alternative product produced may then be used to produce foodstuffs such as cheese according to standard processes for manufacturing such foodstuffs.

The foodstuffs produced from the milk-alternative product are found to have good mechanical properties due to the presence of normal sized oil droplets having an outer shell of oil in the milk emulsion. For example cheese produced from the milk-alternative product grates, slices and represses well and has a good "mouth feel".