The invention relates to stable milk compositions based on wheat gluten. The invention further relates to a method for preparing such stable compositions.

Due to a growing intolerance toward cow's milk, a growing interest in non-dairy milk substitutes is observed in the market. Soya-based milks have become quite popular, and also other non-dairy vegetable milk compositions can be found on the market. Typical examples of such vegetable milk compositions are almond, rice, quinoa, hazelnut and oat based milks.

Typical methods for preparing such plant milks consist in milling the substrate and, when needed, removing solid materials. Several methods for preparing soya milk have been disclosed in the prior art (e.g. EP334057, EP521331 , US4241100, US4885185). US4894242 and WO2007011685 disclose processes for preparing rice milk and WO9604800 pertains to a method for preparing almond milk. Compared to cow's milk, these compositions do not contain lactose or cholesterol. On the other hand, when consuming such plant based milks, problems may arise due to the presence of specific allergens and/or because of taste problems and/or because of stability issues (Hydrocolloids, 2003, p.671-678).

Apart from the above cited vegetable milk compositions, also wheat based milk substitutes have been described in the patent and technical literature. Already in 1913 an artificial milk composition based on wheat gluten is described in GB18382. Thereby wet wheat gluten, freshly extracted from wheat flour, is dispersed in a slightly alkaline medium. To this dispersion sugar is added and the mixture is heated to a temperature of about 70-100°C Fat is then emulsified into this base liquid under very energetic mechanical treatment. In a preferred embodiment the emulsification is performed at about 100°C, thereby providing a sterilised milk substitute. Because of the high temperatures, quite long processing times, and the alkaline conditions, off-taste an off-flavours are formed. The storage stability of the end product is also limited. In CN1065977 (1992) an alternative method is described for producing a wheat milk. Thereby a wet wheat gluten composition is added to an aqueous medium containing a selection of organic acids including citric acid, lactic acid, ascorbic acid, and/or glucono-delta-lactone, or mixtures thereof, in order to obtain a dispersion containing 4-10% protein. This composition is violently mixed to prepare a suspension with relatively low surface tension. To this suspension vegetable oil is added and violently stirred for 5-15 minutes in order to obtain a stable emulsion. Then a proper amount of sugar(s) is added. This wheat milk composition has a pH of 5,0-5,2 and is heated and sterilised.

Also here the wheat milk product is directly prepared from a side stream of wheat flour processing. Here the wet gluten fraction is acidified in order to increase its dispersibility. Quite intense mixing is needed in order to obtain a homogenised composition. The product thereby obtained has a pH different from natural milk, and a reduced storage stability is observed. In both cases, limited storage stability is due to the high molecular weight of the protein fractions in wheat gluten, and of the low number of charges present in the protein backbones.

Use of modified wheat gluten as an alternative protein source in calf milk replacer formulations is widely known. EP446987 describes calf milk replacer compositions wherein at least part of the vegetable proteins consist of soluble wheat gluten. The soluble wheat gluten cited in this application were obtained by deamidation or by partial enzymatic hydrolysis of vital wheat gluten. EP934700 discloses a process for preparing calf milk replacer compositions wherein part of the proteins consist of a mixture of hydrolysed soya protein and hydrolysed wheat gluten. Also here the hydrolysed wheat gluten can be obtained by the processes cited above.

The modified wheat gluten used in calf milk replacers are always incorporated together with other vegetable and/or milk proteins in order to have a balanced amino acid composition in these CMR's. If necessary, essential amino acids can be added. CMR's containing only modified wheat gluten are not used. Special requirements, as in the case of consumer products, regarding organoleptic properties and storage stability are less relevant for CMR's.

In J. of Agricultural and Food Chemistry (1965) p.407-410, a method for preparing enzyme modified wheat gluten is disclosed. The method consists in an enzymatic hydrolysis using pepsin. These modified wheat gluten are used for preparing skimmed milk-like products which are composed of the modified wheat protein, a starch hydrolysate and a stabiliser. These ingredients are spray dried together using conditions whereby well dispersible compositions are obtained. The protein fraction was first neutralised to pH=6, 5-6,6. The spray dried compositions are typically composed of about 30% protein, 70% carbohydrate and 0,7-1% stabiliser. The milklike products prepared therewith contain about 13% d.s..

The milk-like products disclosed in this document contain no fat but still they need a quite substantial quantity of a stabiliser in order to keep the protein fraction in suspension. Thereby the protein hydrolysate was neutralised, thus increasing the salt content of the composition while at the same time reducing the solubility of the protein hydrolysate.

The different wheat protein based vegetable milk compositions cited above show a number of shortcomings mainly to their storage stability and consumer acceptability (flavour, taste, organoleptic properties), and also to their preparation. Thereby the applicant observed that all these shortcomings were related, in one or another way, to the nature of the wheat gluten proteins used in these compositions. It is therefore a purpose of the present invention to provide suitable wheat protein compositions showing improved organoleptic properties and improved storage stability. It is also a purpose of the present invention to allow the preparation of wheat protein based vegetable milk compositions in a technically more feasible way. The above cited problems have now been solved by the compositions of the invention. The invention provides a wheat based milk composition which comprises a carbohydrate source, a lipid fraction and a wheat protein fraction, characterised in that the wheat protein fraction is composed of:

a first modified wheat gluten having a solubility of at least 55% NSI at pH 7 and a degree of hydrolysis between 1 and 4,

and a second modified wheat gluten having a deamidation degree of at least 50%, a solubility of at least 85% NSI at pH 7, and a degree of hydrolysis lower than 0,5. The deamidation degree was determined according to the method described in J. Agric. Food Chem. (1976) p.504-510. The NSI (Nitrogen Solubility Index) is measured according to AACC standard methods at pH=7. The degree of hydrolysis (DH) was determined with the Sorenson formol titration method.

The first modified wheat gluten is an enzyme hydrolysed wheat gluten. The enzyme selected for performing the hydrolysis typically is an endoprotease acting at neutral or slightly alcaline pH, such as e.g. alcalase, corolase, proteinase T. In a preferred embodiment the degree of hydrolysis of the first modified wheat gluten is from 1 ,5 to 2,5. Typical examples of such modified wheat proteins are commercialised under the name of a.o. Meripro 500, Meripro 810, Gempro, GBS- P51 , or Hyfoama. The second modified wheat gluten is a chemically modified wheat gluten obtained by acid or alkaline deamidation, acid deamidation being preferred. Thereby the deamidation degree is at least 50%, preferably at least 55%. Typical examples of such second modified wheat proteins are a.o. Meripro 711 , or GemTec 300 and GemTec 1160.

The ratio of the first modified wheat gluten over the second modified wheat gluten is between 80/20 to 99/1 , preferably between 90/10 and 96/4.

The wheat based milk composition of the invention shows a clear improvement in stability. Furthermore the composition is pH neutral and therefore does not need additional treatment for adapting said pH.

The wheat based milk compositions of the invention contain between 5 and 15% dry matter. This dry matter comprises:

- a carbohydrate fraction representing 1 ,0-7%, preferably 2-4% by weight of the wheat milk composition,

a lipid fraction representing 0,1-5%, preferably 1-2% by weight of the wheat milk composition, a protein fraction representing 1-5%, preferably 2-4% by weight of the wheat milk composition.

The carbohydrate fraction may contain sucrose, invert sugar, HFCS, glucose, fructose, or starch hydrolysates including maltodextrins, and mixtures thereof. Thereby it was found advantageous to combine a maltodextrin with one or more of the other carbohydrate sources.

The lipid fraction is selected among the wide range of vegetable oils, provided they do not induce off flavours. Thereby vegetable oils containing unsaturated or polyunsaturated fatty acids are preferred. Typical examples are rapeseed, sunflower, peanut, maize or sesame oil, or mixtures thereof.

Minor ingredients present in the wheat milk compositions of the invention include an emulsifier and a stabiliser composition, and further a flavouring agent. The emulsifier used typically has an HLB value varying between 8 and 15. Thereby preferably lecithin or a derivative thereof is used. The stabilisers used are selected among a series of hydrocolloids such as xanthan gum, carrageenan, gum acacia, guar gum, gellan gum or mixtures thereof. Suitable quantities of stabiliser used vary between 0,05 and 0,5% by weight of the milk composition. In a preferred embodiment xanthan gum is used in a quantity varying between 0,1 and 0,25% by weight of the milk composition.

The wheat based milk compositions of the invention can be flavoured from a selection of flavours including a.o. vanilla, cocoa, strawberry, orange, banana, as the more popular flavours.

This application further discloses a process for preparing wheat based milk compositions. Thereby the carbohydrate fraction, the stabiliser fraction and the protein fraction are mixed together and dissolved in water in a first mixing vat, and heated up. In a second mixing vat the lipid fraction, together with the emulsifier are mixed together and heated up. Finally both fractions are mixed together in the correct ratios and pressure homogenised, using pressures of between 50 and 300 bar, in a first stage and about 20 bar in a second stage. In a preferred embodiment, the pressure in the first stage is from 100 to 200 bar.

The homogenised wheat-based milk compositions are then pasteurised or submitted to an UHT-treatment. Homogenisation is typically performed by high pressure homogenisation equipment used in the dairy industry, but also mechanical homogenisation can be performed using e.g. Ultra Turrax or Ystral dispersing equipment. The invention will now be further illustrated by the examples hereafter. Example 1 :

This example describes the preparation of wheat-based milk compositions of the reduced fat milk type. The compositions thus obtained are evaluated organoleptically and for their stability against phase demixing over time. The compositon of the wheat-based milks is presented in table 1. The reference products Ref1 and Ref2 only contain enzyme modified wheat gluten and no chemically modified wheat gluten. Table 1 : Compositon of wheat-based milks

Ingredients

Compl Comp2 Ref1 Ref2

(g d.sJIOO ml)

Wheat protein 3,70 3,70 3,70 3,70

Meripro 500 / Meripro

96/4 96/4 100/0 100/0

711 ratio

Carbohydrate

Sugar 2,2 2,2 2,2 2,2

Maltodextrin DE12 0 2 0 2

Rapeseed oil 1 ,4 1 ,4 1 ,4 1 ,4

Xanthan gum 0,2 0,2 0,2 0,2

Lecithin 0,08 0,08 0,08 0,08

Flavour 0,17 0,17 0,17 0,17

Water 92,25 90,25 92,25 90,25 Meripro 500 is an enzyme modified wheat gluten having a degree of hydrolysis of 1 ,5 to 2 and a solubility of at least 60% NSI at pH=7, commercialised by SYRAL SAS. Meripro 711 is a chemically modified wheat gluten having a deamidation degree of about 60% and a solubility of at least 90% NSI at pH=7, commercialised by SYRAL SAS.

The wheat-based milk compositions are prepared as follows:

In a first mixing vessel, protein, carbohydrate and stabiliser are dispersed in water and heated to about 70°C (phase 1 ). In a second mixing vessel oil is heated to 70°C and lecithin is added until homogeneous (phase 2). Then phase 2 is slowly added to phase 1 and mixed with an IKA blender until the temperature is below 60°C. This mixture is then pre-heated to 75°C and homogenised using a high pressure pump from Niro-Soavi using a two step homogenisation procedure. Homogenisation pressures used are 100 and 20 bar. The thus prepared compositions are pasteurised at 90°C and one part is stored at 6°C for 3 weeks. The second part is used for an organoleptic evaluation.

In the sensory analysis represented in Fig. 1 the products Compl and Comp2 were compared with a commercial soya drink which was sweetened and flavoured to a level equal to that of products Compl and Comp2.

The stability over time of the wheat based milk compositions is determined by measuring the aqueous supernatant formed during storage over 3 weeks. The wheat based milks were stored in 1 liter round flasks, which were filed to a height of about 12-13 cm. Stability was expressed as a function (X - Y)/X, whereby, X = the height of the milk composition in the recipient, and Y = height of the aqueous supernatant formed during storage over 3 weeks. Results are given in table 2. Table 2: Storage stability of wheat-based milks

Storage stability Compl Comp2 Ref1

( X-Y)/X 0,88 0,88 0,72 The storage stability of the combined products enzyme modified and chemically modified wheat gluten (Compl and Comp2) is clearly better than the enzyme only modified wheat gluten product (Rett ). From these values it is clear that the combination of a first modified wheat gluten having a solubility of at least 60% NSI at pH 7 and a degree of hydrolysis between 1 and 4, and a second modified wheat gluten having a deamidation degree of at least 50%, a solubility of at least 90% NSI at pH 7, and a degree of hydrolysis lower than 0,5 provides a clear stability improvement over compositions containing only the enzyme modified wheat gluten. Example 2:

In this example wheat based milk compositions having varying protein ratios, varying protein content and varying lipid content are described. The wheat based milk compositions described in this example were prepared using the procedure disclosed in example 1. All formulations thus obtained were homogeneous and showed a milk-like appearance. The composition of the wheat-based milks is provided in table 3.

Example 3:

As a comparative example, the enzymatically hydrolysed wheat gluten (Meripro 500) in example 1 , was replaced by native wheat gluten and processed according to the procedure disclosed in example 1. The dispersions thus obtained were not stable and separated on standing.

Example 4:

In this example, a wheat-based milk composition, containing the same ingredients as for composition 1 (Example 1 ) was prepared using a mechanical homogenisation step, thereby using an IKA high shear mixer. Homogenisation was performed for 10 minutes at 24000 rpm. The resulting composition was homogeneous and showed a milk-like appearance. There was no dephasing after 14 days. Table 3: Wheat-based milk compositions containing varying protein mix ratios, varying protein content and varying lipid content