WO2007003760A1

WO2007003760A1 - Method and installation for improving the spreadability of butter

Info

Publication number: WO2007003760A1
Application number: PCT/FR2006/001502
Authority: WO
Inventors: Sylvain Delerue
Original assignee: Sylvain Delerue
Priority date: 2005-06-28
Filing date: 2006-06-28
Publication date: 2007-01-11
Also published as: FR2887399A1

Abstract

The invention relates to a method for the continuous transformation of a butter, known as normal butter, into a butter having improved spreadability when removed from a refrigerator, known as cold-spreadable butter. The inventive method comprises the following steps consisting in: a) treating the normal butter such as to increase the contact surface thereof; b) crystallising the butter at an initial temperature (T1) by means of accelerated cooling, with the butter being maintained at rest throughout the entire cooling process, in order to bring the temperature to a crystallisation end temperature (T2) which is lower than the initial temperature (T1); and c) decrystallising the butter by means of mechanical working in order to bring same to a final temperature (T3) which is greater than the crystallisation end temperature (T2) and, in this way, to obtain the cold-spreadable butter. The method is characterised in that the cooling process is performed until the butter reaches a temperature of at least -8 °C with the butter being maintained at rest and in that the mechanical working step reduces the crystallised solid masses to approximately 30 µm on average.

Description

Process and installation for improving the spread of butter

The present invention relates to a process for continuously processing a low spread butter, butter whose spread is improved, and an installation for the implementation of this process.

Butter is a food product obtained by maturing cream from milk and by the intensive churning of this cream. Churning aims to break the fat globules that make up the cream, and separate the aqueous phase or buttermilk, fat phase or butter.

These steps are carried out, either in a cask tumbler during a so-called "artisanal" manufacture, or in a butyrator in the case of industrial manufacture.

A butyrator makes it possible to manufacture butter continuously, that is to say that the cream penetrates at one end of the machine and the butter comes out at the other end, in the form of a bead which is then packaged into wafers. The butter thus obtained has good taste characteristics but poor spreadability at the temperature at which it is stored in a refrigerator (4 to 6 ° C).

Indeed, without special treatment, and after a passage in the refrigerator to cool it to a temperature below + 8 ° C, before its marketing, which is mandatory to meet the sanitary standards, the butter has a poor spread when the consumer pulls it out of his refrigerator. It is friable and brittle and can not be spread.

The concept of "Spreadability" is defined as the ability of butter to spread easily. It is measured using a penetrometer that determines the resistance of a body to penetration. However, butter is a consumer product which, for reasons of hygiene, must be kept in the refrigerator. As a result, when the consumer leaves the refrigerator, it is too hard to be spread immediately.

Consumption surveys show that the consumer would like to have an easily spreadable butter right out of the refrigerator, that is to say while still at a temperature between 4 and 6 ° C, without having to wait for the butter to warm up. There are already known on the market several products having a good spread at these temperatures: margarine, lightened butter and a butter easily spreadable, known under the trademark "soft butter".

Margarine is made from hydrogenated oil. It has the advantage for the consumer not to harden in the refrigerator and incidentally not to contain saturated fatty acid, but it has a taste very far from that of butter.

Light butter consists of 25% or 40% of milk fat and for the rest of water, starch and several additives. It is currently little manufactured because it requires a reorganization of the butter manufacturing plants. Although it is presented as a lighter product, it lacks taste.

Finally, the "soft butter" has the advantage of preserving the taste of "classic" butter while being unctuous and easily spreadable as soon as it leaves the refrigerator. A first technique for manufacturing this easily spreadable butter consists in modifying the proportion of the various fatty acids present in the starting cream, by adding oleic acid, which has the effect of lowering the melting point of the butter obtained. .

A second technique currently used is a batch process which consists in taking butter, hereinafter referred to as "hard butter", obtained after a common manufacturing process, to package it in cubes of about 25 kg and place these cubes in the freezer at -18 ° C for seven to eight days. During this stage, the butter crystallises. These cubes of butter are then heated to bring them to a mean temperature of between 0 and 10 ° C., so that they can be introduced into a kneader where they are kneaded until they have the spreadability characteristics of an easily spreadable butter. This mechanical action makes it possible to destroy the crystalline bonds and to soften the texture of the final butter.

This discontinuous production process has the disadvantage of being long, since it requires a storage of butter for a week and be expensive, since it involves the immobilization of freezers and a stock of goods for periods long, more improvement by this technique is not maintained over time, in fact the breaking of the cold chain causes a recrystallization that restores the product its initial texture. The cost price of "easily spreadable butter" thus obtained is high and this type of butter remains a high-end product. In addition, this batch process involves many manipulations of the butter since it left the butyrator until the packaging of the finished product and these manipulations are a potential source of bacterial contamination. In order to overcome these drawbacks, it has already been proposed, in accordance with document FR 2 865 352, a process for treating butter in post-manufacture and continuously, during which the butter undergoes a pressure drop accompanied by a drop in temperature. . However, the improvement in spreadability obtained was not satisfactory. US Pat. No. 3,017,275 already discloses a process for producing an easily spreadable butter at the outlet of the refrigerator. This document presents a method of treating butter during manufacture to produce a butter whose spread is improved. This process is carried out by cooling the fat, either after the formation of the grain of butter, or after the agglomeration of grains in a mass, in a barrel tumbler. The cooling is carried out by means of a chilled sodium chloride solution at a temperature of between minus 21 ^° C. and minus 9 ° C., in order to cool the butter to a temperature of between plus 7 ° C. and minus 4 ° C. The cooling of the butter being difficult, this document indicates that the butter must be stirred to promote heat exchange.

Finally, the document EP 1 027 824 describes a method and an installation for improving the spread of butter.

The butter is fed through a dispensing nozzle on a roll whose walls are cooled with a cooling fluid. In contact with the roll, the butter is cooled from + 16 ° C to + 4 ° C by conduction. After having traveled three quarters of a turn in contact with the roller, the butter falls by gravity on a worm, also cooled and in contact with which it is moved and stirred. Cooling and brewing continue, then the butter is discharged to a mixing plant, provided with cooling means. During this mixing, the butter fat is brought to a temperature between -2 ° C and + 6 ° C, so that the butter is only little or not warmed during this kneading step.

The present invention aims to improve the spread of butter. More precisely, it relates to a process of transformation, operating continuously, of a butter called "normal" butter, whose spreadability soon the output of the refrigerator is improved, this butter being hereinafter referred to as "butter spreadable cold".

The object of the invention is to provide a process that is faster and less expensive than those known from the state of the art. In the following description and claims, the term butter

"normal" means butter, as obtained after a conventional manufacturing process at the outlet of a butyrator, a barrel-tumbler or a temporary storage silo or as withdrawn from a production line before passing through a packaging machine. Furthermore, the term "butter spreadable cold" means a butter that is flexible enough to be spread easily, as soon as the consumer out of the refrigerator, that is to say at a temperature between 4 and 6 ⁰ C and which keeps over time this improved spreadability.

For this purpose, the invention relates to the aforementioned method, which comprises the following steps:

a) treating said normal butter so as to increase its surface intended to come into contact with cooling means,

b) crystallizing the butter at a so-called "initial" temperature by accelerated cooling, to bring it to a crystallization end temperature, lower than said initial temperature,

- Decrystallizing the butter by a mechanical kneading action to bring it to a final temperature above the end of crystallization temperature and thus obtain said butter spreadable cold.

According to the invention, the crystallization step is carried out until the butter reaches a crystallization end temperature of at least

-8 ° C, while maintaining it at rest, throughout the cooling and butter mixing is carried out so as to split the crystallized solid masses and reduce their size to an average maximum value of about 30 microns.

According to other advantageous and nonlimiting features of the invention taken alone or in combination:

the crystallization step is carried out until the butter reaches a crystallization end temperature of between -8 ° C. and -18 ° C .;

the mixing is carried out under a pressure greater than atmospheric pressure; the initial temperature of the butter is between + 10 ° C. and

+ 18 ° C; the butter is heated between steps a) and b) so that its initial temperature is between + 18 ° C and + 28 ^° C .;

the accelerated crystallization is carried out by a temperature drop of at least three degrees Celsius per minute; accelerated crystallization is effected by a temperature drop of at least ten degrees Celsius per minute;

the accelerated cooling is carried out by convection, using a flow of gas directed on the butter;

the final temperature after mixing is at most + 6 ° C; the mixing is carried out in such a way as to homogenize the distribution of the solid and liquid phases of the butter and to heat the butter with an amplitude of at least ten degrees Celsius.

The invention also relates to a continuous processing plant, a butter called "normal", butter whose spread at the outlet of the refrigerator is improved, said "butter spreadable cold".

According to the invention, the installation comprises: extrusion means making it possible to increase the contact surface of the normal butter,

crystallization means making it possible to bring the butter, which is at a so-called "initial" temperature, to an end-of-crystallization temperature lower than the initial temperature and below -8 ° C., while keeping it at rest, during any the duration of the cooling,

- Butter mixing means for breaking crystallized solid clumps and reduce their size to a maximum average value of about 30 microns.

Preferably, the crystallization means are a convection freezing tunnel comprising a conveyor on which the extruded butter is moved and a gas spray ramp on the butter.

Advantageously, the mixing means comprise means for advancing the butter and at least one row of rotating fins arranged in front of a die plate whose orifices restrict the passage of the butter and make it possible to increase the pressure to which it is subjected. up to a value greater than the atmospheric pressure.

Other features and advantages of the invention will appear from the description which will now be made, with reference to the accompanying drawings, which represent, by way of indication but not limitation, possible embodiments. On these drawings:

FIGS. 1 to 3 are graphs showing the evolution of the temperature of the butter over time in accordance with the process of the invention, and this, according to three variant embodiments thereof, FIGS. 4 and 6 are diagrams representing the installations according to the invention, capable of being used for the implementation of the aforementioned method,

FIG. 5 is a diagram, seen from above, of an installation according to FIG. 4, and FIGS. 7 and 8 are diagrammatic views respectively from the side and from the front of a rotary blade provided with a series of FIG. fins.

It is already known from the state of the art a process for making butter spread improved, which consists in particular crystallize butter, by cooling, and then decristallize by kneading. The process according to the invention consisted in selecting and optimizing the operational parameters used during the crystallization and decistallization steps, so as to obtain a butter whose spread-out at the refrigerator outlet is further improved.

In milk, fatty acids bind to each other to form triglycerides.

Butter is composed of 200 to 300 different triglycerides, depending on the diet (fodder or grass) of cows. Their difference is a function of the length of the carbon chain and the number of double and / or triple bonds of this chain. At a given temperature, the triglycerides are either in the liquid state or in the solid state. When the butter is cooled, the triglycerides in the liquid state crystallize between them, as soon as they reach their melting point.

During crystallization, the solid triglycerides bind and form a crystal lattice, in the form of sheets or clusters.

A fat crystal is formed by triglycerides which bind to each other according to their common characteristics: size, melting point, number of double and / or triple bonds.

Since there are 200 to 300 different glycerides, the crystalline combinations are numerous but we retain three large crystal structures:

o-type crystals with a hexagonal structure; the β 'tube crystals, with an orthorhombic structure, and

the β-type crystals, with a triclinic structure.

But these crystalline bonds can be formed only if the internal pressure is stable, because the internal movements of the butter move the triglycerides between them and the bonds can not be established.

The tests carried out by the applicant have shown that it is necessary not only that the crystallization of the butter be carried out at rest, that is to say without the butter being subjected to internal movements or to shear forces, during any the duration of cooling but also that the kinetics of cooling and the end of crystallization temperature had a significant impact on the type of crystal formed.

The tests have shown that the more the cooling is accelerated and homogeneous, the more α type crystallization is favored.

Finally, the tests carried out also showed that the butter should be brought to fairly low temperatures, that is to say to undergo a freezing treatment.

The different steps of the process according to the invention will now be described with reference to the graph of FIG. 1, which represents on the abscissa the duration of the treatment (time t) and on the ordinate the temperature (T).

An example of an installation allowing the implementation of this method will be described later.

In order to promote the cooling of the butter it is preferable to increase its surface intended to come into contact with cooling means. It can be passed, for example, in an extruder that can flatten it in the form of a thin film or spaghetti.

This extrusion step is schematized between the points A and B. The point B corresponds to the entry of the butter in the crystallization means and the point C corresponds to the entry of the butter in the decristallization means by kneading.

During the extrusion stage, the butter is at an initial temperature Ti of between + 10 ° C. and + 18 ° C. At the end of the cooling step, it is at point C, at an end of crystallization temperature T ₂ , lower than Ti and at least -8 ^° C., preferably between -8 ^° C. and -20 ° C, preferably between -8 ⁰ C and -18 ° C. Above -20 ° C, all triglycerides are considered to have crystallized. This cooling at rest must be carried out according to accelerated cooling kinetics, that is to say at least 30 ^° C. per minute, preferably at least 50 ^° C. per minute, more preferably at least 100 ^° C. per minute.

As mentioned above, this rapid cooling will favor o-type crystallization. However, cooling too brutal, that is to say whose kinetics is greater than ten or twelve degrees Celsius per minute generates a supercooling phenomenon harmful to the creation of α-type crystals.

In addition, the amplitude of cooling during crystallization, that is to say the difference between the initial temperature Ti and the end-of-crystallization temperature T ₂ also has an impact on the formation of α crystals. This difference is preferably at least 18 degrees Celsius, which is the case when passing from a temperature of +10 ^° C. to a temperature of -8 ^° C., more preferably still greater, for example from at least 26 degrees, which is the case when passing from a temperature of 18 ° C to -8 ⁰ C ₅ or even 36 degrees when moving from + 18 ° C to -18 ° C.

The kinetics of the cooling is not necessarily linear, as represented in FIG. 2. It can indeed comprise a bearing, here represented between the points E and F, which corresponds to a period of time during which the cooling temperature is constant. , before being lowered again to the end-of-crystallization temperature T ₂ .

The kinetics and the amplitude of the cooling make it possible to modify not only the type of the triglyceride crystals formed, but also the quantity of liquid material in the butter at a given temperature. It is thus possible to modify the melting point of the butter and to lower it. Complementary tests have shown that the butter spread could be further improved by further increasing the cooling amplitude.

According to the alternative embodiment of the method shown in Figure 3, it is possible after the extrusion step, to warm the butter to bring it to a temperature T ₅ greater than the temperature Ti. The heating takes place between points B and G in Figure 3. It can thus bring the butter at a temperature T ₅ between + 18 ° C and + 28 ° C. In the latter case, one thus reaches a cooling amplitude which can be at most 46 degrees.

When the butter is at the temperature T ₅ , it contains a maximum proportion of triglycerides in the liquid state, which, by cooling rapidly, will form more α type crystals. Mixing has the effect of destroying the crystal lattice by breaking the crystal sheets and of distributing the triglycerides in liquid form, thus acting as a lubricant "between the isolated crystals".

Preferably, it is necessary to carry out this mixing without shearing, over a temperature amplitude large enough to homogenize the distribution of the liquid material and the solid material inside the butter.

Starting from a fairly low temperature level at the end of the crystallization step, namely at least -8 ° C., it is possible to have a relatively high friction and frictional mixing range and a mixing energy sufficient to work the butter and homogenize it.

The mixing must be carried out in such a way as to avoid any shearing force inside the butter and to stir it to the maximum in order to homogenize the triglycerides in the solid state and in the liquid state.

Advantageously, it is avoided to raise the temperature T3 at the end of kneading beyond +6 ^° C. In fact, at higher values, the benefit obtained on the improvement of the butter spreadability is destroyed.

Preferably, the temperature is raised during kneading by at least 10 degrees, and at a rate of at least 1 ° C per minute.

Tests were carried out with a commercially available spreadable butter, said "control" and a butter having undergone the processing treatment according to the process of the invention.

Microscopic photos show that in the butter obtained by the treatment according to the invention, the size of the crystalline clusters decreases. The temperature rise range is large enough for the energy transmitted by the mixing to break up the crystallized solid masses and to reduce their size by 50%, without the temperature of the butter at the output of the kneader no longer exceeding 60 ^%. vs.

It was also observed after the mixing that the size of the crystallized solid masses did not exceed on average about 30 microns. This reduction in the size of the crystallized clusters makes it possible to appreciably improve the spreadability of the cold butter.

By way of comparison, the photographs taken on the control butter show that the homogenization of the butter is not obtained and that there remain inside it important crystalline clusters. If the temperature at the end of the crystallization step has reached -18 ° C or more, it is possible to carry out the kneading in a range of at least 24 degrees. We will now describe an example of installation for the implementation of the aforementioned method.

As can be seen in the diagram of Figure 4, the installation according to the invention comprises five units 1, 4, 3, 5 and 6 extending horizontally along a longitudinal axis X-X '.

The installation is fed with normal butter at its lateral end by external means. It comprises successively, from left to right, a device 1 for increasing the contact surface of the butter, a device 4 for accelerated crystallization of the butter and a device 3 for decrystallizing it. The cryogenic fluid supply is by the unit 6 at the crystallization unit 4. A speed variator 5 synchronizes the speed of arrival of the butter and the speed of movement of the support.

Figure 5 schematically illustrates in top view the aforementioned installation. The direction of movement of the butter inside the installation is represented by arrow I.

The device 1 is for example an extrusion die which makes it possible to form a thin layer of butter approximately 4 to 6 mm thick. This device makes it possible to form a strip of butter whose width is at most that of the conveyor.

This device could also be a die for forming fine spaghetti or cords of butter.

The device 4 is a freezing tunnel. It comprises a conveyor 40, activated by the motor 5 whose speed can be varied. Spray ramps of a cryogenic fluid are arranged above and vertically of the conveyor 40. They are not shown in FIG. 5. They allow the spraying of a jet of gas, such as air, nitrogen or CO ₂ , so as to obtain the convection cooling of the thin blade of butter that moves on the conveyor 40. This freezing tunnel allows to cool the butter at extremely low temperatures of -8 ° and -18 ° C in a very short time.

The spray gas vaporizes and is directed to the tunnel entrance. The gas is advancing counter-current to the butter, which favors the heat exchange. This butter is cooled to a temperature of minus 15 ° C in less than a minute. The butter leaving the cryogenic tunnel is fractionated into chips that fall into the mixer 3. According to a variant not shown in the figures, the cooling and crystallization device may be a bath of cryogenic liquid in which the butter is circulated.

The mixer 3 is equipped with two worms 30 which convey the butter to a mixing member 31. The latter is composed of an alternation of fixed obstacles (non-blunt dies 310) in front of which are placed kneading vanes 311 non-blunt. Their number is not exhaustive and is based on the peculiarities of butter butter cream (winter butter or summer butter, melting butter, ...). The dies plates allow a rise in pressure until reaching values higher than the atmospheric pressure.

The worms push the butter towards the compression zone 32 which extends from the end of the worm 30 to the die plate 310. The blades 311 in rotation allow to create successive deformations and homogenize the butter. Then the butter passes through the die plate 310. The die plate reduces the passage area to brake the butter and raise the internal pressure without reducing the flow.

Advantageously, mixing is carried out at the rate of 1 turn per millimeter of displacement of the butter. The butter undergoes several tens of successive deformations. The repetition of these deformations makes it possible to deform the crystallized clusters and to reduce the average size of these clusters, as well as to improve the distribution of the liquid phase between these solid parts.

Figures 6 and 7 illustrate an advantageous embodiment of a rotary propeller 311 having several fins 312. These fins 312 are preferably thin, for example between 2 and 5 mm. Such a device makes it possible to reduce the size of the crystallized solid masses up to an average maximum value of approximately 30 μm.

At the end of the mixer, the butter is sent to the packaging where it is packed.

To implement the alternative embodiment of the method shown in Figure 3, the installation is slightly modified to interpose between the extrusion means and the freezing tunnel 4, a heating plate, not shown in the figures. This allows to create a warming of the butter film by conduction. Advantageously, the heating soleplate does not exceed 63 ° C. According to another variant embodiment, the installation extends vertically along a longitudinal axis Y-Y '. The butter is fed upstream at its upper part.

The enclosure 1 is fed with normal butter at its upper or upstream end, by external means.

It comprises successively, from top to bottom, a means 1 for increasing the contact surface of the butter, a means 2 for accelerated crystallization of the butter, a means 3 for decrystallizing it, and a means for supplying the fluid cryogen by the unit 6 at the level of the crystallization unit 2.

Claims

1. Process for the continuous transformation, from a "normal" butter, into butter whose spreadability at the end of the refrigerator is improved, known as "cold spread butter", which comprises the following steps:

b) crystallizing the butter at a so-called "initial" temperature (Ti) by accelerated cooling, to bring it to a crystallization end temperature (T ₂ ), lower than said initial temperature (Ti),

-c) decrystallize this butter by a mechanical kneading action to bring it to a final temperature (T ₃ ) greater than the end of crystallization temperature (T ₂ ) and thus obtain said butter spreadable cold, characterized in that crystallization step is conducted until the butter reaches a crystallization end temperature (T ₂ ) of at least -8 ⁰ C, while maintaining it at rest throughout the cooling and that the Kneading of the butter is carried out so as to split the crystallized solid masses and to reduce their dimensions to a mean maximum value of approximately 30 μm.

2. Method according to claim 1, characterized in that the crystallization step is conducted until the butter reaches an end of crystallization temperature (T ₂ ) between -8 ⁰ C and -18 ° C.

3. Method according to claim 1 or 2, characterized in that the kneading is carried out at a pressure greater than atmospheric pressure.

4. Method according to one of the preceding claims, characterized in that the initial temperature of the butter (Ti) is between + 10 ° C and + 18 ° C.

5. Method according to one of claims 1 to 4, characterized in that the butter is heated between steps a) and b) so that its initial temperature is between + 18 ° C and + 28 ° C.

6. Method according to any one of the preceding claims, characterized in that the accelerated crystallization is carried out by a temperature drop of at least three degrees Celsius per minute.

7. Process according to claim 6, characterized in that the accelerated crystallization is carried out by a temperature drop of at least ten degrees Celsius per minute.

8. Method according to one of the preceding claims, characterized in that the accelerated cooling is carried out by convection, using a gas flow directed on the butter.

9. Method according to one of the preceding claims, characterized in that the final temperature after mixing is at most + 6 ° C.

10. Method according to one of the preceding claims, characterized in that the kneading is carried out so as to homogenize the distribution of the solid and liquid phases of the butter and to heat the butter with an amplitude of at least ten degrees Celsius.

11. Continuous processing plant, a butter said

"normal", butter whose spreadability at the outlet of the refrigerator is improved, said "butter spreadable cold", characterized in that it comprises:

extrusion means (1) making it possible to increase the contact surface of the normal butter, crystallization means (4) making it possible to bring the butter at a so-called "initial" temperature (Ti) to a end of crystallization temperature (T ₂ ) below the initial temperature (Ti) and below -8 ^° C., while maintaining it at rest, throughout the cooling period,

butter mixing means (3) making it possible to split the crystallized solid masses and to reduce their dimensions to a mean maximum value of approximately 30 μm.

12. Installation according to claim 11, characterized in that the crystallization means are a convection freezing tunnel comprising a conveyor (40) on which the extruded butter is moved and a gas spray ramp on the butter.

13. Installation according to claim 11 or 12, characterized in that the mixing means (3) comprise means for advancing (30) the butter and at least one row of fins (311) rotating disposed in front of a die plate ( 310) whose orifices restrict the passage of the butter and make it possible to increase the pressure to which it is subjected, up to a value greater than the atmospheric pressure.