GB2395418A

GB2395418A - Heating the surface of cheese

Info

Publication number: GB2395418A
Application number: GB0227365A
Authority: GB
Inventors: Ian William Mcdonald
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-11-23
Filing date: 2002-11-23
Publication date: 2004-05-26
Also published as: GB0227365D0

Abstract

A process for inhibiting the growth of mould on the cut surfaces of cheese comprises heating the surfaces of the cheese at an elevated temperature for a period of time sufficient to effect such inhibition. The heating can be effected before or after the cheese has been packaged.

Description

- 1 Cheese Processing This invention concerns packaging and more

particularly the packaging of cheese.

Many cheeses produced throughout the world are intentionally produced with a surface mould growth, moulds being largely aerobic organisms. Such moulds give a characteristic appearance to the particular type of cheese and the metabolism of the mould adds distinctive flavours to the cheese, brie and camembert being examples of such cheeses.

Cheeses having surface moulds are often manufactured in larger sizes than are desired by the consumer, for example finished cheeses can each be lkg or more whereas consumers often require pieces of 200g or less. Such cheeses therefore have to be cut into smaller portions for retail sale, and for supermarket sale they will often be wrapped in polymeric film or foil for display in refrigerated cabinets.

- 2 In addition to producing smaller pieces of cheese, the mechanical process of cutting, for example using wires or knives, transfers mould spores from the outer surface of the uncut cheese to the cut surfaces of the portions. These spores can then grow on the cut surfaces of the cheese now exposed to oxygen in the air and the freshly cut surface of the cheese.

Although this mould growth is not deleterious to the consumability of the cheese, the cut surfaces soon loose their fresh cut appearance due to patchy mould growth which makes the cheese visually less appealing to potential customers, which in turn can lead to lost sales and wastage. As a result of this problem cheese producers and retailers generally reduce the shelf life of packages of cut cheeses.

The problem can in general be overcome by packaging the cut cheese in airtight packages. However, cheeses having desired surface moulds require aerobic conditions in order to continue the ripening and maturation of the cheese, and indeed wrapping materials for mould ripened cheeses are often perforated to allow access of air or are made of oxygen permeable polymeric materials. It has also been proposed to treat the cut surfaces of cheese with mould inhibiting agents. CA2307416, for example, describes spraying the cut surfaces of cheese with a suspension of natamycin in an aqueous saline solution, and W096/39877 describes the use of mixtures of azodicarbonamide with various organic acids and salts thereof to achieve a similar effect.

The present invention seeks to enable mould ripened cheeses to be packaged in oxygen permeable packages whilst mould growth on the cut surfaces of the cheese is inhibited.

According to the present invention there is provided a process for inhibiting the growth of mould on the cut surface of cheese which comprises heating the surface of the cheese at an elevated

l - 3 - temperature for a period of time sufficient to effect such inhibition. Using the present invention a considerable reduction in the rate of growth of mould on the cut surfaces of cheese can be achieved. Furthermore, the treatment can be effected prior to or subsequent to wrapping or packaging of the cheese.

The length of time and the temperature used to effect the heat treatment of the cut surface of the cheese can be varied within wide limits, and will often be selected according to the type of cheese being treated.

The length of time used for the treatment can be varied subject to its being sufficient to effect inhibition of the growth of the mould on the treated surface at the temperature which is used. Too short a period will be insufficient to bring about the desired inhibition of mould growth. However, excessively long treatment periods will either unnecessarily slow down the packaging process, or require larger packaging machinery, leading to increased costs, or the temperature to which the cut surface is heated will have an adverse effect on the cheese. In general, treatment times will be at least 3 seconds, However they will usually be not more than 15 seconds, a preferred range being from 4 to 10 seconds.

Heating of the cut surface can be effected using a hot surface, a hot air flow or radiant heat.

The temperature of hot surfaces and hot air flows should be sufficiently high to inhibit mould growth after heating the cut surface for relatively short periods of time such as are indicated above.

In general, heat treatment using a hot surface will be effected by contacting the cheese with or without its packaging with a surface at a temperature of at least 50 C. Higher temperatures will usually enable shorter treatment times to be used, but in

- 4 general they should not be so high as to have a deleterious effect on the cut surface, for example leading to permanent colour changes or even to deep melting, and in the case of packaged cheese additionally not to have an adverse effect on the packaging material used. The temperature of the surface with which the cheese, with or without its packaging, is contacted will usually be not more than 140 C. A preferred temperature range is from 65 to 90 C, particularly preferred temperature being about 80 C.

If the cut surface of the cheese is to be heated using hot air, the temperature of the air will usually be higher than that of hot surfaces used for the heat treatment. For example, temperatures of at least 140 C will usually be used, but it is generally preferred to use air flows having temperatures of not more than 220 C. In addition to using higher temperatures for hot air flows compared with hot surfaces, the treatment times may need to be adjusted.

Treatment times using radiant heat will in general be adjusted to allow the cut surface to be heated sufficiently to produce the desired inhibition of mould growth and will therefore depend on the energy output of the source of the radiant heat.

Although existing machines for packaging cheese often rely on heating of the packaging materials, for example heat sealable polymeric films, to effect heat sealing of the packages, the heat required to effect heat sealing is either intentionally not applied directly to the cheese or is only applied to the cheese for a period of time sufficient to seal the film but insufficient to effect mould inhibition. The dwell times used to effect heat sealing of polymeric packaging films are, therefore, selected to be as short as possible consistent with forming a good heat seal and therefore are in general less than one second.

The present invention can be used to inhibit mould growth on the cut surfaces not only of surface moulded cheeses, for example

- 5 brie and camembert, but also on the cut surfaces of cheeses which ripen within cavities in the cheese, for example gorgonzola and stilton. The present invention can also be used to inhibit the growth of moulds on the surfaces of non-moulded cheeses, for example cheddar.

Embodiments of the present invention will now be described with reference to the accompanying drawings in which: Figs. la-e show different types of cheese in cut and uncut states; Figs. 2a-d show methods of heat treating cut surfaces of wedge shaped pieces of cut cheese; and Fig. 3 shows a method of heat treating the cut surfaces of cylindrical cheeses.

Referring to Figs. la-e, Fig. la shows a whole "brie-type" cheese having mould growth on its upper and lower surfaces 1, and also on its cylindrical surface 2.

Figs. lb-c show two wedge-shaped portions which have been cut from the cheese of Fig. la. These portions have two cut surfaces 3 in addition to portions of the upper and lower moulded surfaces 1 and a portion of the curved cylindrical surface 4.

Fig. Id shows a wedge shaped portion of cheese cut from a cylindrical cheese which is significantly taller than "brie-type" cheeses, and so is cut into circular slices before being cut into wedges. Such cut portions have a curved moulded face 5 plus two cut faces 6 defining the wedge, and two further faces 7 and 8, one of which possibly being moulded as shown at 8. Typical of such cheeses are gorgonzola and stilton where mould growth in cavities within the cheese is deliberately encouraged during maturation, but mould growth on cut surfaces of the cheese is undesirable. Heat treatment of such cut

- 6 portions will therefore be effected both on the cut surfaces forming the cut wedge, as shown in Fig. Id, and also on any other cut surfaces such as those which reduced the height of the original cheese to form circular slices. These other cut surfaces can be heat treated using hot air or by contact with a hot surface.

Fig. le is a perspective view of a "Soignon-type" cheese having mould over its outer surface. This type of cheese is usually cut into individual portions in the shape of rounds 9 all having a moulded cylindrical surface 10, the two outer rounds 11 also having one flat moulded surface 12, the remaining rounds 13 having two cut faces 14.

Fig. 2a shows heating of the cut surfaces of the portions shown in Figs. lb-c using hot air flows or radiant heat directed at the cut surfaces forming the wedge, and alternative method is shown in Fig. 2b in which the cut surfaces are carried on a hot conveyor 15. If cut surfaces are left untreated following such heat treatment, the untreated surfaces are preferably subjected to a heat treatment in accordance with the present invention.

Fig. 2c shows the use of two heated conveyor belts 16 set at an angle to conform to that of a wedge of cheese 17 so that the faces forming the angle of the wedge are heat treated simultaneously. Fig. 2d shows an alternative to the embodiment of Fig. 2c, heated blocks 18 being pivotally connected at 19. The angle between the blocks 19 is adjusted to match the wedge angle of the piece of cheese 20, the piece of cheese 20 being pushed between the blocks by a pusher (not shown).

Fig. 3 shows apparatus for heat treating rounds of cheese 9 by passing them between two heated conveyor belts 21.

Alternatively the cut surfaces could be subjected to heat treatment in accordance with the present invention using hot air or radiant heat.

- 7 As will be appreciated, heating of the cut surface can be effected by other methods, for example using hot knives or hot wires r

Claims

1. A process for inhibiting the growth of mould on the cut surface of cheese which comprises heating the surface of the cheese at an elevated temperature for a period of time sufficient to effect such inhibition.

2. A process according to claim 1, wherein the heat treatment is effected for a period of at least 3 seconds.

3. A process according to either of the preceding claims/ wherein the heat treatment is effected for a period of not more than 15 seconds.

4. A process according to any of the preceding claims, where) the heat treatment is effected for a period of from 4 to 10 seconds.

5. A process according to any of the preceding claims, wherein the heat treatment is effected using a hot surface, a hot air flow or radiant heat.

6. A process according to claim 5, wherein the heat treatment is effected using a surface at a temperature of at least 50 C.

7. A process according to claim 5 or claim 6, wherein the heat treatment is effected using a surface at a temperature of not more than 140 C.

8. A process according to any of claims 5 to 7, wherein the heat treatment is effected using a surface at a temperature of from 65 to 90 C.

9. A process according to any of claims 5 to 8, wherein the heat treatment is effected using a surface at a temperature of about 80 C.

10. A process according to any of claims 1 to 4, wherein

heating is effected using an air flow at a temperature of not more than 220 C.

11. A process according to any of the preceding claims, wherein the cheese has been packaged prior the heat treatment.

12. A process according to claim 11, wherein the packaging is permeable to oxygen.

13. A process according to claim 12, wherein the packaging is inherently substantially impermeable to oxygen and is apertured to impart permeability thereto.

14. A process for inhibiting the growth of mould on the cut surface of cheese, the process being substantially as herein described.

15. Cheese which has been subjected to a process according to any of the preceding claims.