GB2035360A

GB2035360A - Fat-continuous emulsions

Info

Publication number: GB2035360A
Application number: GB7939471A
Authority: GB
Original assignee: Unilever PLC
Current assignee: Unilever PLC
Priority date: 1978-11-16
Filing date: 1979-11-14
Publication date: 1980-06-18
Also published as: GB2035360B

Abstract

A process for preparing fat- continuous emulsions, containing 15 to 35% of fat, comprises spraying an aqueous phase, until 65 to 85% is reached, into a liquid fatty phase while maintaining conditions of sufficient shear to increase the viscosity without giving rise to phase inversion, e.g. by spraying the aqueous phase into a pool of liquid fatty phase, after which the emulsion is pumped through a static mixer until a viscous emulsion is obtained, which is subsequently worked and cooled, thereby to obtain a droplet size of 4 to 20 mu m of at least 80% of the droplets.

Description

SPECIFICATION Fat-continuous emulsions The present invention relates to a process of preparing fat-continuous emulsions and to emulsions so prepared.

Conventionally, emulsions of the fat-continuous type contain at least about 35% of fat; such emulsions are generally prepared by gradually adding small amounts of the aqueous phase to the molten fatty phase containing the emulsifier, and cooling and mechanically working the resulting emulsion until a homogeneous emulsion is obtained containing fat crystals in the continuous phase.

The phase volume ratio (fat/aqueous phase) is a limiting factor in the preparation of fat-continuous emulsions by conventional techniques. The process of the present invention allows the preparation of fat-continuous emulsions containing no more than about 15 to 20% of fat.

According to the present invention a fat-continuous emulsion of a fat content of 15-35% is prepared by spraying an aqueous phase into a fatty phase, steadily increasing the content of aqueous phase until a percentage of 65-85% has been reached while maintaining conditions of sufficient shear to increase the viscosity to such an extent that upon cooling and working the emulsion so obtained a droplet size of 4-20 um of at least 80% of the droplets is achieved.

The viscosity required during processing is dependent on the required phase volume ratio of fatty and aqueous phases and the average size of the dispersed phase. Conditions of sufficient shear may be achieved by e.g. a mixing process either in the vessel in which the aqueous phase is sprayed or in an external loop fitted to that vessel. An adequate viscosity can e.g. be achieved by spraying the aqueous phase into a pool of liquid fatty phase which may contain an emulsifier, e.g. a partial glyceride, while the emulsion is pumped through a static mixer until a viscous emulsion is obtained. The degree of viscosity can e.g. be influenced by adjusting the stress of the flow in the static mixer and/or by adding viscosity increasing ingredients.

A suitable final viscosity of an emulsion containing 80% of dispersed phase is e.g. about 18000 cP at a shear rate of 13 sex.~' and 2700 cP at a shear rate of 134 sex. 1, measured at 380C with a Ferranti portable viscometer.

In this Specification the terms "oils" and "fats" are used as synonyms, unless otherwise indicated; a fatty phase is within the scope of the present invention the continuous phase of an emulsion and contains triglyceride oils and fats.

Preferably the emulsion is prepared by spraying the aqueous phase into a vessel containing the liquid fatty phase and by recirculating the emulsion through an external loop fitted with a static mixer while the spraying process continues, after which the emulsion is cooled and worked. Cooling and working can, e.g., take place in a surface-scraped heat exchanger of a Votator A-unit type, to a temperature of about 1 0-20"C. Further crystallisation can, e.g., be effected in a stirrer uncooled crystallizer unit, after which the product is finally packed.

Alternatively, part of the aqueous phase can be added in a conventional margarine manufacturing process and the remainder by the spraying process of the invention.

In this way a fully continuous process can be carried out in which in the steady state the level in the vessel is kept constant by the supply of melted fat and the spray of aqueous phases on the one hand and the take-off of emulsion on the other hand.

The emulsions may contain dispersed droplets of aqueous phase varying in size and composition.

This can e.g. be achieved by spraying into the fatty phase two or more aqueous phases of different compositions and/or by spraying into the fatty phase one or more aqueous phases but in at least two different spray sizes.

By effecting different droplet sizes and/or providing dispersed aqueous phase of different nature, the presence of a not or only slightly releasing part and a well releasing part can be realised, which will increase the flexibility of the product in respect of the degree of flavour release during mastication. It has also been observed that in products containing one gelled and one ungelled aqueous phase subsequent coalescence is inhibited, which will give enhanced resistance to microbiological deterioration.

Generally droplets of 1-2 microns do not release, whereas droplets of 8 or more microns easily release in the mouth. The upper limit of the droplet size is essentially determined by microbiological constraints and should in general not exceed 20 microns. If the emulsion prepared by the invention is intended for bakery purposes, excessive release of the dispersed aqueous phase at temperatures above 10"C should be avoided, since thereby the aeration of the emulsion in the presence of sugar may detrimentally be affected.

By control of the droplet size and/or the nature of the dispersed phase optimal creaming properties can be achieved.

The nature and viscosity of the aqueous phase can easily be influenced by the presence of absence of certain thickening agents and/or the presence or absence of different types of thickening agents in two or more aqueous phases to be sprayed into the fat. Generally the coarser droplets contain the thickening agents.

In principle there are no limitations to the fat or fat blend to be used in the emulsions of the present invention.

Fats that are liquid at room temperature can be used in preparing pourable fat-continuous emulsions and fats that are plastic at room temperature are useful for the preparation of plastic emulsions, e.g. low-fat spreads.

When liquid oils are used together with an aqueous phase containing freezing point depressants, fat-continuous emulsions can be prepared that are spoonable at temperatures below freezing point.

Preferably the fat-continuous emulsions contain a fatty phase of a dilatation value at 10"C of at least 150, preferably at least 250, and at 350C of no more than 100, preferably no more than 25.

The invention will now be illustrated by the following Examples (in which all percentages are by weight).

Example 1 a W/O type emulsion was prepared from the following ingredients: Aqueous phase wt. % Water 77.650 Salt 1.750 Lactic acid to pH 4.5 0.100 Fatty Phase wt. % Fat blend of the following dilation values: at 10"C 640 20 15"C 425 20"C 248 25"C 130 30"C 48 35"C 25 Hymono Sf 44 0.550 Vitamins and colour 0.0425 Flavours 0.0075.

The process was carried out as follows: 1) The aqueous phase was sprayed onto the fatty phase contained in a vessel at 38do. The droplet sizes from the spray were approx. 150-220 um.

2) During the addition of the sprayed aqueous phase the emulsion was recirculated through an external loop attached to the vessel and fitted with a static mixer (the maximum viscosity 18000 cP at shear rate 13.0 sec.-'; and 2700 cP at shear rate 134 sec.-l measured at 38 C, was reached at the completion of the addition ofthe aqueous phase).

3) The emulsion obtained was subsequently cooled to 13"C in a Votator A-unit and further crystallized in an uncooled stirred crystallizer unit and packed at 21"C. The average droplet size of the dispersed aqueous phase was 5 y Example lI Another fat-continuous emulsion was prepared from the following ingredients: lsf Aqueous phase wt.% Water 30.00 Salt 2.500 Lactic acid to pH 4.8 0.003 2ndAqueousphase wt.% Water / 45.780 Carageenan 0.619 Locust bean gum 0.316 Potassium chloride 0.148 Lactic acid to pH 4.8 0.003 Fatty phase Fat blend (same as that of Example 1) 20.00 Hymono Sf 44 0.600 Colour 0.015 Flavours 0.016.

The process was carried out as follows: 1) The aqueous phase (1) was sprayed onto the fatty phase at 38"C. The droplet sizes from the spray were approx. 150-220 um. The emulsion was further thickened by recirculation through a static mixer (18000 cP/13.0 sex71; 2700 cP/134 sex.~1) measured at 38"C.

2) The aqueous phase (2) was sprayed onto the emulsion at 38"C with controlled shear to get water droplets in final product of approx. 7 um.

3) The emulsion obtained was further treated as described in Example I. The average size of the ungelled droplets was 4 u and the gelled droplets 10 u Example Ill To improve palate response an emulsion having larger water droplets was formulated. An aqueous phase, which gelled rapidly on contact with the fatty phase, was used; this resulted in a stable suspension of gelled droplets in oil. A product with a satisfactory organoleptic response resulted. The emulsion was prepared from: Aqueous phase wt.% Water 75.179 Salt 2.750 Potassium sorbate 0.134 Lactic acid to pH 4.8 0.006 Carageenan 0.800 Locust bean gum 0.544 Potassium chloride 0.256 Fatty phase Fat blend (same as that of Example I) 20.00 Hymono Sf 44 0.300 Colour 0.015 Flavours 0.016.

The process was carried out as follows: 1) The aqueous phase was made up and held at 90"C.

2) The fatty phase was made up and held at 38"C.

3) The aqueous phase was sprayed onto the fatty phase keeping the bulk temperature at 38do.

4) The emulsion was recirculated through an external static mixer to give a stable emulsion. The product was further treated as described in Example 1. The average droplet size was 6 u

Claims

1. Process for preparing a fat-continuous emulsion of a fat content of 15-35% by spraying an aqueous phase into a liquid phase, steadily increasing the content of aqueous phase until a percentage of 65-85% has been reached while maintaining conditions of sufficient shear to increase the viscosity to such an extent, that upon cooling and working the emulsion so obtained, a droplet size of 4-20 um of at least 80% of the droplets is achieved.

2. Process according to claim 1 in which the emulsion is prepared by spraying the aqueous phase into a vessel containing the liquid fatty phase and by recirculating the emulsion through an external loop fitted with a static mixer while the spraying process continues, after which the emulsion is cooled and worked.

3. Process according to claim 1 or 2, with particular reference to the Examples.

4. Fat-continuous emulsions obtained by the process of any one of the claims 1-3.