GB2257345A

GB2257345A - Process for prepaing a food dressing

Info

Publication number: GB2257345A
Application number: GB9115908A
Authority: GB
Inventors: David Alexander Simpson; Robin Henry Simpson
Original assignee: Elsner Ltd
Current assignee: Elsner Ltd
Priority date: 1991-07-10
Filing date: 1991-07-23
Publication date: 1993-01-13
Anticipated expiration: 2011-07-23
Also published as: IE66897B1; GB2257345B; BE1003150A6; GB9115908D0; IE912411A1

Abstract

A process for preparing a food dressing emulsion in which a discontinuous phase such as oil is finely dispersed in an aqueous continuous phase. The discontinuous phase is added to the continuous phase in a controlled manner in a colloid mill 18 having a relatively large emulsifying gap. A vacuum is applied to mixing vessel 10 and continuous phase liquid water is sucked in. Then other ingredients such as tomato puree and vinegar are sucked in. The contents of the mixing vessel are circulated through colloid mill 18 while other ingredients are added through valve 48 at inlet 19. The entire mixture is circulated through the colloid mill to homogenise it and form the dressing. <IMAGE>

Description

"A Process for Preparing a Food Dressing This invention relates to a process for preparing a food dressing, and in particular sauces for flavouring food.

The term food dressing as used throughout this patent specification is taken to include real mayonnaise, salad mayonnaise, salad cream, salad dressings and other flavoured sauces such as tomato ketchup, brown sauce and the like.

Many dressings are emulsions made with vegetable oil. An emulsion is made from two liquids which do not dissolve in each other, like oil and water for example, but normally exist as two separate phases. An emulsion is formed when one of these two liquids is finely dispersed as droplets in the other liquid. The droplets are called the discontinuous or dispersed phase; the liquid in which they are dispersed is called the continuous phase. To make an emulsion stable an emulsifier is necessary to stop the discontinuous phase recombining.

Mayonnaise and salad creams are emulsions consisting of an oil phase (discontinuous phase) and an aqueous phase (continuous phase). The aqueous phase may typically comprise water, vinegar, egg and flavouring. The quantities of oil used depend on the product, and for a good quality product the oil content may be somewhat as follows; Real mayonnaise minimum 75% oil Salad mayonnaise minimum 50% oil Salad dressings minimum 35% oil Salad cream minimum 25% oil The above percentages are given on a weight/weight basis, the percentage of oil including the fat content of egg yolk used.

To produce a stable emulsion with egg yolk (i.e. an emulsion which does not easily separate), the oil phase must be provided as the dispersed phase. That is, the oil phase in droplet form is finely dispersed in the continuous aqueous phase. This even applies to mayonnaise with 84% oil content.

Emulsions of this type are referred to as oil in water types.

An emulsifier, such as egg yolk, reduces interfacial tension between the two phases by reinforcing the contact surface between them.

When adding the oil to the aqueous phase great care must be taken as if the oil is added too fast then inversion can occur. An inverted mayonnaise is where the water is dispersed in the oil phase and it is unstable and will finally separate into two layers. Egg yolk only functions as an emulsifier when the oil is dispersed in the water phase. Therefore to avoid inversion care must be taken particularly at the start of the mix of the oil and aqueous phases.

In producing a mayonnaise emulsion it is important to provide a consistent product that is a homogenous blend of an aqueous phase (water, vinegar, egg, flavour) and an oil phase (vegetable oil). There are a number of difficulties in producing a high quality product. To produce the emulsion the aqueous phase and oil phase may be mixed in a colloid mill by passing them through a relatively narrow emulsifying gap, formed between a stator and a rotor of the colloid mill. The shear forces induced by the emulsifying gap ensure dispersion of the oil in the aqueous phase thus forming the emulsion.

However a disadvantage is that the shear forces also caus the temperature of the emulsion to rise. High temperatures adversely affect the product. Emulsion failure can result from excessive temperatures. Further, production output is limited due to the relatively narrow emulsifying gap which restricts the throughput of the product.

A further problem is that any air inclusions in the product can adversely affect the product. For example the product may discolour or become rancid.

The present invention is directed towards overcoming these problems.

According to the invention there is provided a process for preparing a food dressing comprising the steps; (a) preparing preset quantities of ingredient materials, (b) applying a vacuum to a mixing vessel, (c) sucking a preset quantity of a continuous phase liquid into the mixing vessel, (d) sucking a selected portion of the ingredient materials into the mixing vessel, (e) circulating the contents of the mixing vessel through a colloid mill and back to the mixing vessel whilst adding the remaining ingredient materials in a controlled manner at an inlet to the colloid mill to form a mixture of the continuous phase liquid and ingredient materials, the colloid mill having an emulsifying gap in the order of 2.6 - 4.5 mm, (f) circulating the mixture through the colloid mill for a preset time period to fully blend and homogenise the mixture thus forming the food dressing, (g) delivering the food dressing to a holding tank, and (h) discharging the food dressing from the holding tank into containers and sealing the containers.

Preferably the process includes the step of chilling the continuous phase liquid prior to delivering the continuous phase liquid to the mixing vessel.

In a particularly preferred embodiment of the invention the food dressing is mayonnaise and the process comprises; (a) preparing preset quantities of ingredient materials including a discontinuous phase liquid, the discontinuous phase liquid being chilled, (b) applying a vacuum to a mixing vessel, (c) sucking a preset quantity of a continuous phase liquid into the mixing vessel, chilling the continuous phase liquid before delivery to the mixing vessel, (d) sucking additional continuous phase ingredients int the mixing vessel, the additional ingredients including egg, sugar, salt, mustard and vinegar, the vinegar being added last, (e) circulating the continuous phase liquid and additional ingredients through a colloid mill and back to the mixing vessel for a preset period to mix the continuous phase liquid and ingredients, (f) circulating the mixed continuous phase through the colloid mill whilst adding the chilled discontinuous phase liquid in a controlled manner to the continuous phase at an inlet to the colloid mill to disperse the discontinuous phase liquid as droplets in the continuous phase thus forming a mayonnaise emulsion, (g) circulating the mayonnaise through the colloid mill for a preset time period, (h) delivering the mayonnaise to a holding tank, and (i) discharging the mayonnaise from the holding tank into containers and sealing the containers.

In another aspect the invention provides an apparatus for carrying out the process described above.

The invention will be more clearly understood by the follcwing description of an embodiment thereof given by way of example only, with reference to the accompanying drawing which is a schematic illustration of a food dressing production system according to the invention.

The apparatus comprises a cylindrical mixing vessel 10 with a conical lower portion 11 terminating in an outlet 12. A vacuum pump 13 is connected to the mixing vessel 10 by a vacuum line 14. An outlet pipe 16 communicates between the outlet 12 and a colloid mill 18 having an inlet 19 and an outlet 20. A discharge line 21 connected to the outlet 20 leads to a three-way valve 22 which is operable to connect outlets of the three-way valve 22 - with either the mixing vessel 10 or a dressing holding tank 24. Mounted at an outlet of the holding tank 24 is a discharge pump 25.

A pair of discontinuous phase liquid storage tanks 30 are provided, in this case the discontinuous phase liquid comprising vegetable oil. A discontinuous phase supply line 31 communicates between the storage tanks 30 and a discontinuous phase dosing tank 32. Mounted in the discontinuous phase supply line 31 are a chiller 33, a filter 34 and pumps 35. An outlet of the dosing tank 32 communicates by a dosing pipe 36 with the outlet pipe 16 adjacent the inlet 19 of the colloid mill 18. An orifice plate 37 and valve 38 are mounted in the dosing pipe 36.

A continuous phase liquid, in this case water, is supplied through a continuous phase liquid line 40 connected to the mixing vessel 10. A continuous phase inlet valve 41, counter 42 and a chiller 43 are provided in the continuous phase liquid line 40.

A starch gum dosing line 45 connects through a valve 46 with the outlet pipe 16 adjacent the inlet line 19 of the colloid mill 18. Dosing lines 47 for additional ingredients such as vinegar, egg, sugar and salt connect through a valve 48 with the outlet pipe 16 adjacent to the inlet 19 of the colloid mill 18.

Use of the apparatus will now be described for the production of a salad mayonnaise. The vacuum pump 13 is operated to set and maintain a vacuum of about 500 mbar in the mixing vessel 10. Discontinuous phase liquid from one of the storage tanks 30 is metered into the dosing tank 32. The temperature of the discontinuous phase liquid is cooled in the chiller 33 prior to delivery to the dosing tank 32. Continuous phase liquid is metered into the mixing vessel 10, the temperature of the continuous phase liquid being reduced in the water chiller 43.

A thickening agent such as starch is dispersed in a small amount of vegetable oil and delivered to a starch dosing hopper (not shown) which connects with the starch dosing line 45.

With the mixing vessel 10 under vacuum the valve 48 is opened and additional continuous phase ingredients including egg, sugar, salt, mustard and vinegar are sucked into the mixing vessel 10. It will be noted that the vinegar is the last ingredient to be added. The valve 48 is then closed.

The colloid mill 18 is started and the continuous phase liquid and ingredients are circulated from the mixing vessel 10 through the colloid mill 18 and back through the three-way valve 22 into the mixing vessel 10 to mix the continuous Phase ingredients. After approximately 15-30 seconds, the valve 46 is opened to mix in the starch. When all the starch is added the valve 46 is closed. The continuous phase mixture is circulated through the colloid mill 18 for approximately 15 seconds to homogenise the mixture.

The valve 38 is then opened and discontinuous phase liquid from the dosing tank 32 is introduced to the circulating continuous phase mixture adjacent the inlet 19 of the colloid mill 18. The discontinuous phase liquid can be added at a rate of approximately 50/60 1 per minute. When all the discontinuous phase liquid has been added the valve 38 is shut and the mayonnaise emulsion is circulated through the colloid mill 18 for 15-30 seconds. Then the vacuum within the mixing vessel 10 is broken and the three-way valve 22 is switched over to deliver the mayonnaise into the holding tank 24. On reaching the holding tank 24 the mayonnaise should be at approximately ambient temperature. The mayonnaise is then discharged from the holding tank 24 by the pump 25 into containers which are subsequently sealed.

A process for producing real mayonnaise is largely similar to the process described above for preparing salad mayonnaise, however in this case no thickening agents are used and the real mayonnaise contains a higher proportion of the discontinuous phase liquid. The discontinuous phase liquid in this case is added to the continuous phase at a rate of approximately 20 - 30 1 per minute initially, increasing to 40 - 60 1 per minute.

The improved mayonnaise production process according to the invention has a number of advantages. Firstly with regard to the colloid mill, while an enlargement of the emulsifying gap might be expected to produce a less homogenous and consistent product, it has been found in practice that a high quality blending of the discontinuous phase liquid and continuous phase liquid can still be achieved even with the enlarged emulsifying gap. Advantageously less heat is generated in the product by passage through the enlarged emulsifying gap.

Further, flow resistance is reduced and the product can be circulated more quickly through the colloid mill thus reducing overall processing time and allowing increased production.

The maximum temperature of the product during the process is also advantageously limited by pre-chilling the continuous phase liquid and discontinuous phase liquid. By regulating the initial temperature of these liquids depending on ambient conditions and by regulating the blending times the temperature of the mayonnaise produced can advantageously be limited to the ambient temperature.

Elimination of air from the product by production under vacuum conditions give a more stable product which is less susceptible to discolouration or becoming rancid.

The process and apparatus can also be used to prepare other food dressings such as tomato based sauces, for example tomato ketchup. In this case when the vacuum has been applied to the mixing vessel 10 water is sucked into the mixing vessel 10.

Tomato puree and vinegar are then sucked into the mixing vessel 10, the vinegar being added last. Dry ingredients such as spices and flavourings are prepared and mixed. The colloid mill 18 is started and the contents of the mixing vessel 10 are circulated through the colloid mill 18 and back to the mixing vessel 10 whilst adding the dry ingredient materials in a controlled manner through the valve 48 at the inlet 19 of the colloid mill 18 to form a mixture of the water and ingredient materials. This mixture is circulated through the colloid mill 18 for a preset period, depending on the quality and nature of the ingredients to fully blend the mixture forming a smooth homogenous ketchup. The three-way valve 22 is then operated to direct the ketchup into the holding tank 24 from where it is pumped into containers which are subsequently sealed.

The invention is not limited to the embodiments hereinbefore described which may be varied in detail.

Claims

1. A process for preparing a food dressing comprising the steps; (a) preparing preset quantities of ingredient materials, (b) applying a vacuum to a mixing vessel, (c) sucking a preset quantity of a continuous phase liquid into the mixing vessel, (d) sucking a selected portion of the ingredient materials into the mixing vessel, (e) circulating the contents of the mixing vessel through a colloid mill and back to the mixing vessel whilst adding the remaining ingredient materials in a controlled manner at an inlet to the colloid mill to form a mixture of the continuous phase liquid and ingredient materials, the colloid mill having an emulsifying gap of between 2.6 mm and 4.5 mm, (f) circulating the mixture through the colloid mili for a preset period to fully blend and homogenise the mixture thus forming the food dressing, (g) delivering the food dressing to a holding tank, and (h) discharging the food dressing from the holding tank into containers and sealing the containers.

2. A process as claimed in claim 1 including the step of chilling the continuous phase prior to delivering the continuous phase liquid to the mixing vessel.

3. A process as claimed in any preceding claim wherein the food dressing is mayonnaise and the process comprises; (a) preparing preset quantities of ingredient materials including a discontinuous phase liquid, the discontinuous phase liquid being chilled, (b) applying a vacuum to a mixing vessel, (c) sucking a preset quantity of a continuous phase liquid into the mixing vessel, chilling the continuous phase liquid before delivery to the mixing vessel, (d) sucking additional continuous phase ingredients into the mixing vessel, the additional ingredients egg, sugar, salt, mustard and vinegar, the vinegar being added last, (e) circulating the continuous phase liquid and additional ingredients through a colloid mill and back to the mixing vessel for a preset period to mix the continuous phase liquid and ingredients, (f) circulating the mixed continuous phase through the colloid mill whilst adding the chilled discontinuous phase liquid in a controlled manner to the continuous phase at an inlet to the colloid mill to disperse the discontinuous phase liquid as droplets in the continuous phase thus forming a mayonnaise emulsion, (g) circulating the mayonnaise through the colloid mill for a preset time period, (h) delivering the mayonnaise to a holding tank, and (i) discharging. the mayonnaise from the holding tank into containers and sealing the containers.

4. A process substantially as hereinbefore described with reference to the accompanying drawings.

5. A food dressing whenever produced by a process as claimed in any preceding claim.

6. An apparatus substantially as hereinbefore described with reference to the accompanying drawings for carrying out the process as claimed in any preceding claim.