Field of the invention

The present invention relates to a new coating or packaging for water-containing products such as food products or food ingredients, in particular cheese and sausage, and the use of such a coating.

Background of the invention

During and after ripening, cheeses and sausages are coated to prevent physical damage, to reduce or prevent loss of moisture, to maintain a desired shape or to protect against undesired fungi including yeasts and bacteria. Hard, semi-hard or soft cheeses and various sausages such as matured sausages like salami or chorizo can be protected in this way by a coating. The protective coating consists in general of a plastic or polymer coating (for example a (co-) polymer based on vinyl acetate) that can be applied in a single layer or multiple layers. For some types of food, the coating needs to be flexible because of volume changes of the food during ripening. A skilled person will be able to select a proper polymer regarding its flexibility, depending on the type of food to be coated. An outer layer of wax, generally on basis of paraffin, can be applied on the polymer coating to block evaporative water loss and to block further ripening.

Detailed description of the invention

According to the present invention, a coating is provided that is significantly peelable or strippable. This means that the peelable coating may be removed from the surface that it coats, simply by mechanical peeling. The coating is peelable during and after storage, without the need to pack the product in plastic foil or other packaging material. A peelable coating possesses sufficient flexibility and strength so that it does not fracture during peeling. Preferably, the adhesive ability of the coating is sufficient to keep it completely bound to the underlying surface during the period of protection and yet remains peelable at the time of removal. Preferably, the peelable coating is peeled off without being torn in pieces. Advantageously, parts of at least 5 cm ² can be peeled off; preferably parts of at least 10 cm ² , and more preferably at least parts of 20 cm ² can be

peeled off in one piece. A useful coating when removed should not remain partially unpeeled, and thus not leaving parts of coating adhering to the coated surface. By peelable coating is also preferably meant a coating, which is formed by a water-borne polymer dispersion, and whereby the polymers and/or other ingredients present in this dispersion are used to obtain the peelable effect.

By mechanical peeling is meant that it can be peeled by a suitable apparatus or by hand. In general, the present invention relates to a peelable coating for water containing products, preferably for those types of products that are respiring. More preferably, the product is a food product or a food ingredient. A food product or food ingredient that is respiring implies that it respires gasses like CO ₂ due to natural ripening and / or water vapour that evaporate from the food. Respiration depends on the speed of ripening, which is related to the temperature, moisture content and acidity. Respiration also depends on the use of ripening bacteria. Respiration of water is related to the water contents of the food, the shape of the food (surface area related to volume), and the relative humidity, temperature and air circulation of the storage facilities.

According to the present invention a peelable coating is provided. We have found that the ease of peeling is related to the barrier properties of the coating. Increasing the barrier to gas and / or water or water vapour makes the coating more peelable. The relation between barrier and peelability that we have found forms the basis of the present invention. The present invention uses this relation to provide water-borne polymer suspensions which when used as coating result in a coating that is peelable. Although this relation is used to explain this present invention, the present invention is in no way restricted or bound to this theory. The coating of the present invention results in (possibly) temporary protection of food products. After peeling off the coating, the food can be processed as if it was never coated, while having had the advantage of protection by the coating. For example, it can be sliced, ground, cooked and eaten as a whole. It will lead to higher yields through the direct effect of preventing loss caused by cutting off coating including cutting off an outer layer of the food, and through the effect of reduced labour for removing the coating. Moreover the peelability allows new applications of respiring food that were previously impossible or uneconomical. Although several times food products or food ingredients are mentioned as suitable products to be coated, in fact all water-containing products can be coated according to the present invention to obtain the peelable coating. The food

product or food ingredient will advantageously be in a solid or paste-like state. The coating is not intended for liquids.

The present invention relates to a peelable coating, which is obtained by coating the surface of a water-containing food product or food ingredient that respires water, whereby the food product or food ingredient is coated with a water-borne polymer dispersion comprising a (one or more) polymer or a (one or more) copolymer to form a peelable coating. The formed coating has better barrier properties than prior art coatings, including coatings based on dispersions containing copolymers of vinyl acetate-dibutylmaleate. According to a preferred embodiment, the polymers or copolymers used for preparing the peelable coating of the invention comprises at least one of the following polymers or copolymers: polyethylene, poly (ethylene vinyl acetate), poly (vinyl acetate-vinyl ester of carboxylic acid) or poly (acrylate), or a mixture thereof or, possibly mixed with other dispersions. Preferably, the peelable coating has a permeability of less than 12 mg/cm ² 24h of water. More preferably, the permeability of the coating is less than 10 mg/cm ² 24h of water, even more preferably more than 0.5 mg/cm ² 24h of water and most preferably between 0.5 and 10 mg/cm ² 24h of water. The preferred water-borne polymer dispersion comprises polymers or copolymers of polyethylene, poly (vinyl acetate- vinyl ester of carboxylic acid) or poly (acrylate) or mixture thereof. The coating can be used on for example food products or food ingredients.

The permeability can be observed by the weight loss of the coated respiring food product or food ingredient (expressed in mg per surface area per day). It can be determined by preparing coating films in such a way that dried films have the same thickness as used in the actual application. These dried films are attached on top of a holder that contains water. The holders are conditioned at 2OO and 60% RH (Relative Humity). Permeability is determined by measuring weight loss caused by evaporation of water through a total coating surface of 12cm ² , and is expressed in mg/cm ² 24h of water. Permeability is determined after 24 hours giving the result in mg/cm ² 24h of water.

Further ingredients may be present in the coating according to the present invention. Such ingredients can be essentially similar to all the ingredients that are applied in coatings, including dispersions of polymers such as copolymers of vinyl acetate- dibutylmaleate. A person skilled in the art will have no difficulty in selecting these further

-A-

ingredients. Further ingredients may also include fibres, for example polyester fibres, to enhance the solidity of the coating.

The present invention also relates to a peelable coating, which is obtained by coating the surface of a water-containing food product or food ingredient that respires water, with a water-borne coating, including coatings based on dispersions containing copolymers of vinyl acetate-dibutylmaleate, or a coating according to the present invention as described above, to which further compounds are added to enhance barrier properties, resulting in a permeability of less than 12 mg/cm ² 24h when applied on food products or food ingredients, preferably less than 10 and preferably more than 0.5 mg/cm ² 24h of water. These compounds comprise at least one of the following compounds: paraffin or wax or other hydrophobic substances that can be mixed with the dispersion, polymer resins with barrier properties such as (mixtures of) polyethylene, copolymers based on ethylene such as Poly (Ethylene-Vinyl Acetate) or poly(tetrafluoro-ethylene) or mixture thereof.

The present invention also relates to a peelable coating, which is obtained by coating the surface of a water-containing food product or food ingredient that respires water, whereby the food product or food ingredient is coated with a water-borne polymer dispersion, which comprises a polymer or a copolymer to form a peelable coating. Preferably, the water-borne polymer dispersion comprises at least one of the following compounds: paraffin or wax or other hydrophobic substances that can be mixed with the dispersion, polymer resins with barrier properties such as (mixtures of) polyethylene, copolymers based on ethylene such as Poly (Ethylene-Vinyl Acetate) or poly(tetrafluoro-ethylene) or mixture thereof.

The coating can be applied in one or multiple layers. A multi-layered coating can be composed of one or more layers of coating according to the present invention, possibly combined with one or more layers of coatings of different composition. A similar one- or multiple-layered coating can be applied on a different substrate, and used as a packaging material for food and food ingredients.

Accordingly, the invention also relates to a process to coat the surface of a water- containing food product or food ingredient that respires water, whereby the food product

or food ingredient is coated with a water-borne polymer dispersion, which comprises a polymer or a copolymer to form a peelable coating as defined before. Preferably, in this process, the peelable coating has a permeability of less than 12 mg/cm ² 24 h, preferably between 0.5 and 10 mg/cm ² 24h of water. According to another preferred embodiment, the water-borne polymer dispersion used in this process comprises at least one of the following polymers or copolymers: polyethylene, poly (ethylene-vinyl acetate), poly (vinyl acetate-vinyl ester of carboxylic acid) or poly (acrylate), or a mixture tiereof. More preferably, the water-borne polymer dispersion further comprises at least one of the following compounds: paraffin, wax, polymer resin with barrier properties such as (mixtures of) polyethylene, copolymer based on ethylene such as Poly (Ethylene- Vinyl Acetate) or poly(tetrafluoro-ethylene) or mixture thereof.

According to another preferred embodiment, the invention also relates to a process to coat the surface of a water-containing food product or food ingredient that respires water, whereby the food product or food ingredient is coated with a water-borne polymer dispersion, which comprises a polymer or a copolymer to form a peelable coating as defined before. Preferably, in this process, the peelable coating has a permeability of less than 12 mg/cm ² 24 h, preferably between 0.5 and 10 mg/cm ² 24h of water. More preferably, the water-borne polymer dispersion used in this process comprises at least one of the following compounds: paraffin, wax, polymer resin with barrier properties such as (mixtures of) polyethylene, copolymer based on ethylene such as Poly (Ethylene- Vinyl Acetate) or poly(tetrafluoro-ethylene) or mixture thereof.

The present invention further relates to food products and food ingredients coated with the coating as defined above. Application can be manual (e.g. with sponge or brush), semi-automatic or automatic (e.g. by brushing, dipping or spraying) depending on the number of foodstuffs to be treated. Specialised cheese coating and sausage coating machines are commercially available. Application can be done according to a procedure similar to the coating protocol for commercially available coating products such as Plasticoat ^® , Delvocoat ^® or Premicoat ^® . The skilled person in the art will have no difficulty to select the proper number / frequency of coating treatments. Machine settings can be modified in an empirical way in order to produce a specific end result in terms of coating application. In general, coating viscosity is regulated and the coating is applied in such

way that uniform coating takes place. In order to allow a regular and even distribution of the coating, it is required to individually fix treatment schemes for each kind of food.

The present invention further relates to the use of a water-borne polymer dispersion to form the peelable coating present on the surface of a food product or food ingredient as defined before. Preferably, the peelable coating has a permeability of less than 12 mg/cm ² 24h of water. According to another preferred embodiment, the water- borne polymer dispersion used comprises at least one of the following polymers or copolymers: polyethylene, poly (ethylene-vinyl acetate), poly (vinyl acetate-vinyl ester of carboxylic acid) or poly (acrylate), or mixtures thereof.

The present invention will now be illustrated by the following examples, which should not be construed as limiting the scope of the invention.

EXAMPLES

Material and methods

Materials

Base polymers used

Mowilith LDM 1481 , a copolymer from vinyl acetate and ethene, approx. 51% purchased by Celanese GmBH, Division Emulsions, D-65926 Frankfurt am Main.

Mowilith LDM 5041 , a copolymer from vinyl acetate and butyl acrylate, approx. 45% purchased by Celanese GmBH, Division Emulsions, D-65926 Frankfurt am Main.

Mowilith DV, a homo polymer from vinyl acetate, approx. 50%, purchased by Celanese GmBH, Division Emulsions, D-65926 Frankfurt am Main. - Craymul 4376, a copolymer from vinyl actate and dibutylmaleate, approx. 45% purchased by Cray Valley B.V. (Brummen, the Netherlands).

Other ingredients

Di-sodium-EDTA, purchased by Chemolanda bv, 2596 BP Den Haag, The Netherlands.

Ammonia, purchased by Gaches Chimie France, 31750 Escalquens, France.

Tylopur MHB3000P, purchased by Clariant GmBH, Division Cellulose Ethers & Polymerisates, D-65926 Frankfurt am Main.

Delvocid®, containing 50% (w/w) active natamycin, DSM Food Specialties, P.O. Box 1 , 2600 MA, Delft, The Netherlands. - Blanose 7 HF, carboxy methyl cellulose purchased by Hercules Inc, division

Aqualon, SPCI, 19 rue des Bretons, B.P.43, 93212 St-DENIS LA PLAINE CEDEX FRANCE

Keltrol BT, modified xanthan gum purchased by CP Kelco, division food, Industrieweg P.O. Box 1 , 3583 Beringen Belgium. - Plasticoat ^® AGD 322, regular cheese coating. DSM Food Specialties, P.O. Box 1 ,

2600 MA, Delft, The Netherlands.

Michem Emulsion 37135, polyethylene wax emulsion from Michelman Inc., Ohio USA, purchased by Keyser & Mackay, Leidsegracht 19, 1017 NA, Amsterdam, The Netherlands.

Example 1

This example describes a method to prepare a formulation suitable for use as a standard meat coating by dipping treatment.

The mixture was made with an electrical top stirrer, type RW 20 DZM, from Janke & Kunkel equipped with a Ruston-type stirrer.

The mixture was prepared by adding 900 gram Mowilith DV 50, 900 gram Mowilith LDM

5041 , 3 gram Delvocid ^® and 2 gram Di-sodium-EDTA together.

This crude mixture was mixed for 5 minutes to obtain a homogeneous mixture and accordingly adjusted to pH = 6.0 ± 0.5 by slowly adding ammonia. The obtained mixture was stored at 18 O in a closed bucket in the dark until the moment of usage.

Example 2

This example describes a method to prepare a formulation suitable for use as a meat coating by dipping treatment.

The mixture was made with an electrical top stirrer, type RW 20 DZM, from Janke & Kunkel equipped with a Ruston-type stirrer.

The mixture was prepared by adding 1800 gram Mowilith LDM 1481 , 195 gram demineralised water, 3 gram Delvocid ^® and 2 gram Di-sodium-EDTA together. This crude mixture was mixed for 5 minutes t> obtain a homogeneous mixture and accordingly adjusted to pH = 6.0 ± 0.5 by slowly adding ammonia. The obtained mixture was stored at 18 O in a closed bucket in the dark until the moment of usage.

Example 3

This example describes a method to prepare a formulation suitable for use as a food coating and specially a cheese coating. In order to adapt the viscosity to standard base polymers for cheese, an additional thickener was added to the base polymer Mowilith

LDM 1481.

The mixtures were made with an electric top stirrer, type RW 20 DZM from Janke &

Kunkel equipped with a planetary mixer. The mixtures were prepared by adding 34 gram thickener solution to a 166 gram Mowilith

LDM 1481 base polymer solution. Total weight was made up to 200 gram. This crude mixture was mixed for 30 minutes to obtain a homogeneous mixture. The thickener solutions were made as stock solution. Stock solutions were prepared by dispersion and hydration of the thickeners in demineralised water. The thickener mixtures were made with an electric top stirrer, type RW 20 DZM from Janke & Kunkel equipped with a planetary mixer. The mixture was mixed until a viscous clear and transparent solution was reached.

Several mixtures were made:

Coating 1 comprised 166-gram Mowilith LDM 1481 and 34 gram of a 3 % w/w Tylopur MHB 3000 P stock solution.

Coating 2 comprised 166-gram Mowilith LDM 1481 and 34 gram of a 0.5 % w/w Blanose

7 H stock solution.

Coating 3 comprised 166-gram Mowilith LDM 1481 and 34 gram of a 1 % w/w keltrol BT stock solution. Reference coating 4, comprised 182 gram Craymul 4376 and 18 grams of demineralised water.

Reference coating 5, comprising 182 gram Mowilith LDM 1481 and 18 grams of demineralised water.

Coating 6, comprising 175 gram Craymul 4376, 4 gram polyethylene Michem Emulsion 37135 and 21 grams of demineralised water.

The obtained mixtures were stored at 18 °C in closed buckets in the dark until the moment of usage.

Example 4

This example describes the method that was used to analyze the weight losses in time of sausages applied with the coatings as described in example 1 and 2.

The used sausages, dried fermented sausages type "fine cervelat" with an average weight of 600 gram, were purchased by a local sausage producer (Persoon BV at Lisse, the Netherlands).

The coatings were weight and afterwards the coating was applied by dipping. When access of coating was dripped off the sausages were hanged in a ripening room at 12 O and 82 - 85% RH. Weight loss of the coatings was followed on a regular basis.

Example 5

This example describes the method that was used to test the peelability of the coatings after application and sufficient storage. The coating surface is a closed layer and to test peelability an attachment point is made by opening the coating by a sharp subject like a knife. The ease of tearing the coating from the surface gives a good indication of the peelability. The ease of tearing is indicated by 1 , 2 or 3 in the course of which 1 means almost impossible to tear or peel the coating from the surface, 2 means possible to peel but when the coating is teared off it breaks within 1 cm, the coating can only be removed in small parts less than 1 - 5 cm ² , 3 means that it is easy to peel and that the coating can be teared off easily like a banana peel in parts of at least 5 cm ² .

Example 6

According to the method as described in example 4, a series of sausages is dipped in coatings described in example 1 and 2 and weight loss is followed. The results of the weight losses are presented in table 1

Table 1 Weight losses in time as % (w/w).

Example 7

The sausages ripened according to example 6 are tested on peelability as described in example 5. The coating prepared in example 2 was easily removed and was peelable. As to the coating prepared in example 1 , it was more difficult to make an attachment point and the coating was almost not peelable.

Example 8 This example describes the results obtained from preparing a coating film on a glass plate to evaluate the peelability. The dispersions as described in example 3 (coating 1 to 6) were drawn on glass substrates by using a pulling bar with adjustable slit height (200 μm and 635 μn) and were left to dry uncovered for at least 12 hours under normal conditions. (55 %RH, 23 ⁰ C). The dry films were tested on their peelability as indicated in example 5.

The results are presented in table 2.

Table 2: Results of the peelability of the dry films on glass as substrate.

Example 9

This example describes the results obtained from dipping cheeses in dispersions as described in example 3 (coating 1 to 6). The following mini cheeses were used as substrates: commercial available as Mini Babybel® (Groupe Bel, France). The paraffin of

these mini cheeses was removed. The mini cheeses were dipped in the formulations as presented in table 3 below and were left to dry for at least 12 hours at room temperature (55 % RH, 23 ⁰ C). Dry films were tested on their peelability as indicated in example 5. One cheese was dipped in reference coating 4 and then two times in coating 1 (coating 4+1 +1 as indicated in table 3 below), whereby the cheese was left to dry for at least 12 hours at room temperature in between the multiple applications. The results are presented in table 3.

Reference coating 4, with water vapour permeability higher than 12 mg/cm ² 24h (see Example 10) is not peelable.

Coatings 1 , 2, 3 and 6 according to our invention, can be easily peeled from cheese. Coating 1 according to our invention can be easily peeled from cheese, also when applied in combination with a coating of different composition (coating 4). Coating 5 is also peelable, but to a less extent than coatings 1 , 2, 3 and 6.

Example 10

In the following experiment, the method for determination of the water vapour permeability of coatings is demonstrated.

Coating films are prepared in such a way that the dried films have the same thickness as in the actual application. The films are attached on top of a holder that contains water.

The holders are conditioned at 2OO and 60% RH. Water vapour permeability is determined by measuring weight loss caused by evaporation of water through a total coating surface of 12cm ² , and is expressed in mg/cm ² 24h. Water vapour permeability is determined after 24 hours and after 48 or 72 hours, all giving the same result in mg/cm ² 24h.

Example 11 This example describes the results obtained from films composed from coating 1 or coating 4 as described in example 3, and applied as described in example 9.

The test was performed in threefold and the used coatings made had an average thickness of 0,5 mm, for both coatings 1 and 4, as in the application described in example 9. The found permeability was 3.0 mg/cm ² 24h (RH=60%, T=20°C) for coating 1 , and 19 mg/cm ² 24h (RH 60%, T=20 ^< O) for coating 4.

Example 12

This example describes the results obtained from a coating film prepared by applying several coating layers on cheese, to evaluate the peelability. Coatings were applied with a sponge on 4-kg Gouda cheese, to obtain a full covering of the cheese surface. The coating was dried for 1 day, after which the cheese was turned and coating was applied on the other side of the cheese. Then a second or more layers were applied all around the cheese in similar way. The several coating layers merge to form 1 coating layer. A week after applying the fifth layer, the coatings were tested for peelability according to Example 5. The results are given in Table 4. Cheese A was treated with 1 layer of the coating from Example 2, on top of which

4 layers of Plasticoat ^® AGD 322 were applied.

Cheese B was treated with 3 layers of the coating from Example 2. Cheese C was treated with 1 layer of coating 1 from Example 3, on top of which 3 layers of Plasticoat ^® AGD 322 were applied. Cheese D was treated with 1 layer of reference coating 4 from Example 3, on top of which 3 layers of Plasticoat ^® AGD 322 were applied.

Table 4 Results of the peelability of a multiple-layer coating from cheese substrate

The coatings according to our invention can be easily peeled from cheese, also when applied in multiple layers (cheese B) and when applied in combination with a coating of different composition (cheese A and C). Reference coating 4 from example 4 was not peelable according to Examples 8 and 9 and is also not peelable from cheese when combined with regular (non peelable) cheese coating Plasticoat ^® AGD 322 (cheese D).