FR2663510A1 - Process for the treatment of poultry for plucking them and plant for implementing the process - Google Patents

Abstract

The invention relates to a process for the treatment of poultry for plucking them as well as to a plant for implementing the process. The latter comprises the various steps consisting in: a) prewashing the poultry with water; b) removing fat from the feathers of the poultry by soaking them in a bath containing surfactants; c) soaking the poultry in a bath containing a hydrating agent such as glycerol.

Description

PROCESS FOR TREATING POULTRY FOR THEIR FEATHER
AND INSTALLATION FOR IMPLEMENTING THE PROCESS
The present invention relates to a method for treating poultry with a view to plucking them, as well as an installation for implementing this method.

 Although it can be applied to all kinds of poultry, in particular palmipedes, the method of the invention is particularly suitable for the treatment of Muscovy ducks, prior to their plucking.

 While the plucking of many poultry takes place after scalding (soaking the animal in a hot water bath) which facilitates the removal of feathers, the plucking of ducks, especially Muscovy, continues to be done dry because the feathers of these animals are covered with a fatty coating which prevents water from penetrating to the skin. The wettability of the skin could probably be increased by using very hot water or steam, but this treatment would have disastrous consequences on the appearance of the skin of poultry.

 Dry plucking is essentially about plucking the feathers using rotary disc pluckers. The work is completed by traditional pluckers with rubberized fingers.

 However, the plucking remains incomplete so that, to tear down the down still in place on the skin, it is necessary to carry out a treatment with hot wax. To do this, each animal is immersed in a wax bath at a temperature of the order of 600C; after cooling, it is wrapped in a shell which is peeled, the wax then causing the downs still in place on the skin.

 This technique has serious drawbacks. Indeed this kind of treatment sometimes leaves traces on the skin due to burns, bruises or other injuries. In addition there remains on the skin remnants of wax, down, or even feathers. The animal is therefore difficult to sell. However, it was found that at the time of purchase the consumer was very sensitive to the surface appearance of poultry.

 In addition, the implementation of this technique is very expensive, very painful and noisy for the staff.

 The present invention aims to remedy these drawbacks. To do this, it proposes a method for treating poultry which makes it possible to "prepare" them for plucking. This process aims to modify the natural characteristics of feathers and skin so that plucking can be done easily, without the skin being damaged, which is particularly important when poultry is marketed as a fresh product.

 It is a simple process to implement and can be easily integrated into a slaughter and plucking chain.

This process is essentially characterized in that it comprises the stages which consist in
a) prewash poultry with water
b) degrease poultry feathers by soaking them in a bath containing surfactants
c) soak the poultry in a bath containing a moisturizing agent.

According to other advantageous but non-limiting characteristics:
- the hydrating agent is glycerol
- the glycerol concentration is around 1%
- between steps b) and c), the poultry is rinsed with water
- the prewash is carried out by spraying the poultry
- rinsing is done by spraying poultry
- the degreasing bath includes
- an alkyl-sulfate or an alkyl-phenyl sulfonate
- a polyglycolic alkylphenol ether
- water-soluble mineral additives, at least of which
a sequestering agent and at least one electrolyte
whose role is to lower the value of the concen
critical micellar bath tration
- the alkyl sulphate is sodium dodecyl sulphate and the alkyl phenyl sulphonate is sodium dodecyl benzene sulphonate
- in step a), the prewash is carried out with water whose temperature is between 30 and 540C and for at most 1.5 minutes
- in step b), degreasing is carried out in a bath whose temperature is between 30 and 540C and for 30 seconds to 3 minutes
- in step c), the hydration is carried out in a bath whose temperature is between 49 and 550C and for three minutes at most
The invention also relates to an installation for implementing this method. It is characterized by the fact that it includes different stations where the poultry are brought successively and subjected to the different stages of the process.

 Other characteristics and advantages of the invention will appear from the description and the appended drawing (FIG. 1) which very schematically represents an embodiment of the installation for the implementation of the invention. In this figure, the lower part of the drawing (which has been cut to fit into the format of sheet 1/1) normally extends to the right the upper part of the drawing.

The installation shown diagrammatically in FIG. 1 essentially comprises four different stations
- a prewash station 1
- a degreasing station 2
- a rinsing station 3
and finally, a hydration station 4.

 Animals C, for example Muscovy ducks, are intended to be suspended from the hooks of a conveying installation 6 which circulates the animals from post to post. The drive means of the installation are of known type and not shown. It is for example an electric motor. The direction of movement of the conveyor is shown by the arrow f.

 The prewash station 1 essentially comprises two vertical ramps 10 on which are installed nozzles 11 for spraying liquid. Contrary to what is shown in FIG. 1 (for the sake of better understanding), these ramps are installed on either side of the conveyor installation so that the poultry pass between the two series of nozzles of projection 11 as they move to station 1.

Evacuation means not shown equip the station 1 so that the liquid projected by the nozzles 11 can be easily recovered.

 The degreasing station 2 essentially consists of a reservoir 20 of liquid 21. At this level, the conveying installation comprises a descending branch 60 which makes it possible to gradually immerse the animals C in the liquid. The descending branch 60 is continued by a horizontal branch 61 then by an ascending branch 62.

 Immediately after the degreasing station 2 is located the rinsing station 3. It should be noted that this station, as well as the following (which are described below), are equipped with a thermally insulating cover 70 fitted at its ends with swing shutters 71, so that heat exchanges with the outside of these stations are very limited.

 The cover 70 is combined with an air conditioning system which diffuses air through nozzles 72.

 The structure of station 3 is similar to that of station 1.

In fact, it comprises two ramps 30 for spraying liquid, equipped with nozzles 31 and arranged on either side of the conveying installation.

 The station 4 includes, like the station 2, a reservoir 40 of liquid 42 into which the animals descend progressively. It is also equipped with devices 9 for blowing air inside the tank, as well as mechanical means for stirring the liquid, not shown, of a type known per se.

 Finally, the installation is completed by a known plucking device 6 and not shown, located downstream.

 We will now explain how the processing of poultry is carried out.

 The first step in the process is to pre-wash the poultry. This operation is carried out at station 1 by spraying (showering) the animals, using water diffused in the form of jets by the nozzles 11. The purpose of this prewash is essentially to rid the body of the poultry of droppings and of 'other defilements. Preferably, the temperature of the water used for this treatment is between 30 and 540C. The length of the prewash station and the speed of advancement of the hooks along the conveyor installation are calculated so that the spraying of the ducks does not exceed 1.5 minutes and is preferably between 5 and 45 seconds.

 This prewashing operation can also be carried out by soaking the poultry in water. However, in this case, the stains removed from the animals' bodies remain suspended in the bath so that it is necessary to change it from time to time. On the contrary, by spraying poultry, this drawback is not encountered, the prewash water being discharged by gravity.

 The second stage of the process consists in degreasing the feathers of poultry. This treatment is carried out at station 2 by soaking the poultry in the tank 20, after they leave station 1.

 The purpose of this operation is to remove the fatty coating that covers the feathers so that, later, you can hydrate the skin for more effective plucking.

This degreasing operation is carried out using surfactants. Good degreasing results are obtained from a mixture comprising
- some water ;
- an anionic surfactant chosen from
- alkyl sulfates,
- alkylphenyl sulfonates
- a nonionic surfactant chosen from polyglycolic alkylphenol ethers
- additives chosen from mineral salts such as
- sodium carbonate
- sodium chloride.

 Particularly preferred surfactants are sodium dodecyl sulfate (hereinafter referred to as SDS) and sodium dodecylbenzene sulfonate.

 Likewise, as nonionic surfactant, polyglycolic nonylphenol (hereinafter referred to as NP7) containing approximately 6 to 8 molecules of ethylene oxide per mole is preferred, as well as polyglycolic octylphenol containing 9 to 10 molecules of ethylene oxide per mole.

 The additives are chosen so as to provide at least one sequestering agent and at least one electrolyte whose role is to lower the value of the critical micellar concentration of the bath. By this expression is meant the limit value of micellization of surfactants in water.

Thus, good degreasing results are obtained by soaking the poultry in the bath 21 which has the following characteristics
- composition: - water
- 0.1% SDS
- NP7 at 0.1%
- NaCl = 0.1 M
- Na2CO3 = 80 mg / l
- bath temperature: 44 C
- soaking time: 30 seconds to 2 minutes.

 The soaking time must be adjusted so as to avoid the solubilization of epidermal lipids which retain, inside the skin, the highly hydrosoluble natural hydrating elements, favorable to good elasticity of the skin, which might be entrained.

 The results relating to this degreasing operation will be found in the table incorporated in the present description.

 The third step of the process consists in rinsing the poultry so as to prevent the active products of the bath 21 from mixing with those of the following station. This rinsing is carried out at station 3 by spraying the poultry with water. Preferably, this treatment must be carried out in an atmosphere that is as isolated as possible from the outside. It is for this reason that the installation described with reference to FIG. 1 comprises a thermally insulating cover 70. The nozzles 72 diffuse air at a temperature between 49 and 550C with 90 to 100% humidity. The water used for rinsing is itself at a temperature between 49 and 550C.

 At the exit of this rinsing station, the poultry are sent to station 4 for the hydration of their skin. To do this, they are soaked in a bath 42 containing glycerol.

The purpose of this treatment is to cause an increase in the elasticity of the skin of poultry, with a view to easier plucking. Glycerol can easily come into contact with the skin due to the fact that it as well as the feathers have been freed of their fatty substances beforehand. This operation is further facilitated by the air intake generated by the devices 9, favoring the creation of micro-bubbles inside the bath which tend to stir the feathers and the liquid with a view to better hydration of the epidermis. In a possible alternative embodiment, submerged rotary brushes stir the feathers of poultry during their passage through the bath.

Good hydration results are obtained with the following parameters
- composition: aqueous glycerol solution at one
0.1% concentration
- temperature: 49 to 550C;
- soaking time: from 30 seconds to 3 minutes.

 Other moisturizers such as sodium lactate and sorbitol can also be used.

 At the exit of this degreasing station, the poultry are transported to a known plucking installation. As an indication, machines which can be used for plucking are described in EP-A-O 294 870.

 In the example below, results are given relating to the appearance of the skin and the plucking of Muscovy ducks, after treatment.

 The numbers 1 to 5 relating to the nets, rump and wings reflect the ease of plucking (1 = very difficult plucking; 5 = easy and effective plucking).

 The figure relating to the skin reflects the appearance of the skin of plucked poultry (1 = very damaged skin; 5: intact skin).

Example
Step a): nature of the liquid = water at 400C;
prewash time = 0.25 minutes.

Step b): nature of the bath = 0.1% SDS
NP7 at 0.1%
0.1 M NaCl
Na2CO3 80 mg / l
water
soaking time = 1 minute
bath temperature = 400C.

Step c): nature of the bath = water
glycerol
soaking time: 2 minutes
bath temperature = 540C.

Results: Nets = 5
Rump = 5
Wings = 4
Skin = 5

Claims (16)

 1. Process for treating poultry, in particular Muscovy ducks with a view to plucking them, which comprises the various stages which consist in  a) prewash poultry with water;  b) degrease poultry feathers by soaking them in a bath containing surface-active agents  c) soak the poultry in a bath containing a moisturizing agent.  2. Method according to claim 1, characterized in that the hydrating agent is glycerol.  3. Method according to claim 2, characterized in that the concentration of glycerol in the bath is approximately 0.1%.  4. Method according to one of claims 1 to 3, characterized in that between steps b) and c), the poultry is rinsed with water.  5. Method according to one of claims 1 to 4, characterized in that the prewash is carried out by spraying the poultry.  6. Method according to one of claims 4 and 5, characterized in that the rinsing is carried out by spraying the poultry.  7. Method according to one of claims 1 to 6, characterized in that the degreasing bath comprises  - an alkyl-sulfate or an alkyl-phenyl sulfonate  - a polyglycolic alkylphenol ether  - water-soluble mineral additives including at least one sequestering agent and at least one electrolyte whose role is to lower the value of the critical micellar concentration of the bath.  8. Method according to claim 7, characterized in that the alkyl sulphate is sodium dodecyl sulphate and the alkyl phenyl sulphonate is sodium dodecyl benzene sulphonate.  9. Method according to one of claims 1 to 8, characterized in that in step a), the prewash is carried out with water whose temperature is between 30 and 540C and for at most 1.5 minutes.  10. Method according to one of claims 1 to 9, characterized in that in step b), degreasing is carried out in a bath whose temperature is between 30 and 540C and for 30 seconds to 3 minutes.  11. Method according to one of claims 1 to 10, characterized in that in step c), the hydration is carried out in a bath whose temperature is between 49 and 550C and for three minutes at most.  12. Installation for implementing the method according to one of claims 1 to 11, characterized in that it comprises  - pre-wash (1) and degreasing (2) stations for poultry (C)  - a post (4) for hydration of poultry skin  as well as a conveyor installation (6) for post-to-post poultry.  13. Installation according to claim 12, characterized in that it further comprises, between the degreasing stations (2) and hydration (4), a rinsing station (3).  14. Installation according to claim 13, characterized in that the prewash (1) and rinsing (3) stations are provided with nozzles (11, 31) for spraying liquid on poultry.  15. Installation according to one of claims 12 to 14, characterized in that each of the degreasing stations (2) and hydration (4) is equipped with a tank (20, 40) in which the poultry are immersed.  16. Installation according to one of claims 13 to 15, characterized in that the rinsing (3) and hydration (4) stations are equipped with a thermally insulating cover (70).