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Process for preparing nutritional compositions

Process for preparing nutritional compositions description/claims

This invention relates to a process for preparing nutritional compositions by extrusion and to nutritional compositions so prepared.

Powdered nutritional compositions containing the macronutrients protein, fat and carbohydrate are well known. They are intended to be reconstituted prior to consumption with a liquid which is usually water but may alternatively be liquid milk or fruit juice. Such products include infant formula, growing up milks and compositions used in clinical nutrition, for example for enteral feeding. Conventionally, such products are manufactured by mixing all the ingredients with water, subjecting the liquid mixture to a thermal treatment to reduce bacterial loads, homogenising the mixture and then spray drying it.

It may be seen that in the manufacturing process described above, water is added only to be removed again by the spray drying process. It will be appreciated that removal of water requires energy in the form of heat and the equipment required takes up a considerable amount of space. In addition, care is required in order to avoid microbial contamination or cross-contamination from other products produced in the same equipment. Accordingly, there is a need to develop an alternative method to produce such compositions which has lower energy requirements and for which the equipment is more compact.

Surprisingly, the present inventors have found that it is possible to extrude a mixture comprising an oil in water emulsion without leading to coalescence or inversion of the emulsion. The emulsion is stable under high shear, high temperatures, high pressures and minimal amount of water in the extruder.

Accordingly, the present invention provides a process for preparing a nutritional composition including protein, fat and carbohydrate which process comprises emulsifying the fat in water with an emulsifier to form an emulsion having a solids content of at least 70%, homogenising the emulsion and extruding the emulsion together with a solid matrix comprising the protein and the carbohydrate in a ratio between 1 part emulsion:0.5 parts matrix to 1 part emulsion:5 parts matrix into a vacuum chamber at a temperature at or above the melting point of the mixture of emulsion and matrix to obtain a solid product having a maximum water content of 10%.

The process of the invention provides a solid product that is easily dispersible upon addition to water or another liquid to give a homogeneous liquid mixture of protein, fat and carbohydrate with no discernible separation of aqueous and non-aqueous phases.

Preferably the nutritional composition is an infant formula.

The process may additionally include a drying step to remove any remaining moisture from the extruded product.

The process may optionally include a milling step whereby the extruded product, which is typically in the form of porous pellets, is reduced to a powder with a higher density.

In the present specification, the following words are given a definition that must be taken into account when reading and interpreting the description, examples and claims.

The term “stable” used to describe the emulsion means that the emulsion is stable with respect to coalescence and/or inversion, both visually determined.

The term “solid matrix” means a mixture of solid ingredients without added liquids

The term “easily disperses” means disperses with a minimum of agitation or stirring.

All percentages are percentages by weight unless otherwise stated.

The properties and constitution of the emulsion are crucial in order to achieve the desired result with respect to dispersibility. Accordingly, the emulsion has a water content of at the most about 30% w/w. It is stable towards coalescence and inversion when extruded with a solid matrix of protein and carbohydrate in a weight ratio of from 1:0.5 to about 1:5 at a temperature at or above the melting point of the mixture of the emulsion and the solid matrix. The thus obtained extruded product is expanded into a vacuum chamber to obtain a solid product having at the most about 10% water content.

The emulsifier may be water soluble or fat soluble. Suitable water soluble emulsifiers include caseinates such as sodium caseinate and potassium caseinate, acid caseinate, other milk fractions that are commonly used as emulsifiers and sugar esters. Suitable fat soluble emulsifiers include lecithins and mono- and diglycerides such as CITREM®. Preferably both water soluble and fat soluble emulsifiers are used. In this case, preferably both the water soluble emulsifier and the fat soluble emulsifier are added to the fat prior to emulsification. The weight ratio between fat and emulsifier may be in the range of from about 10:1 to about 18:1 depending on the amount of water employed. For example, a preferred ratio between fat and emulsifier is about 14:1 at 26% water (ideally 69% fat, 5% emulsifier and 26% water). If the ratio is too low, there is a risk that the emulsion inverts during homogenisation. If, however, the ratio is too high, it is difficult to stabilise small fat particles during the extrusion step.

The fat component may constitute from 50 to 75% w/w of the emulsion. Any fat or mixture of fats generally suitable for nutritional compositions may be used. For example, if the composition is an infant formula, palm olein, coconut oil, canola oil, milk fat and mixtures thereof may be used. Long chain polyunsaturated fatty acids may also be incorporated such as docosahexaenoic acid (from fish oil) and arachidonic acid (from fungal oils such as that obtained from Mortierella alpina). Oil soluble vitamins such as Vitamin E may also be included in the emulsion if desired.

The content of fat in the nutritional composition will vary according to the type of composition and is generally expressed in terms of the contribution made by fat to the overall energy of the composition. For example, in an infant formula, fat generally provides from 30 to 55% of the total energy of the composition depending upon the type of product and the age group for which it is intended.

The emulsion may be homogenized by any method known in the art to reach a mean particle size D[0.5] in the range from 0.2 to 10 μm. A multi-step homogenisation is preferred. In practice, the preferred mean particle size after homogenisation will depend upon the emulsifier being used and the composition of fats which form the emulsion. For example, for a mixture of vegetable fats emulsified with sodium caseinate, D[0.5] preferably lies in the range from 0.2 to 1.5 μm.

• Provisional Patent
• Utility Patent

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