GB2526728A - Food hygiene method and food product - Google Patents

Abstract

A process is described for reducing the number of viable microorganisms, particularly Campylobacter species, present on the surface of meat, especially poultry. The process comprises the steps of rapidly cooling the surface membrane of a contaminated meat item to a given temperature, preferably between -5 and 2°C, and allowing the membrane to warm to a second temperature higher than the first temperature and preferably below 4°C. The process is sufficient to reduce the number of viable bacteria, whilst at the same time retaining in the muscle meat the organoleptic and nutritional qualities of fresh meat as monitored by the level of β-hydroxyacyl-CoA dehydrogenase (HADH) activity in the muscle tissue. The cooling may be achieved by exposure to a cryogen.

Description

Food Hygiene Method and Food Product

Summary

S The invention relates to a process for reducing the number of viable microorganisms present on the surface of meat, and to meat items so treated.

Introduction

Food-borne pathogens represent a significant and serious threat to human and animal health. Numerous species of microorganism reside naturally on many types of food, some of which are capable of causing diseases in man (and other animals) upon ingestion. Sensible precautions, such as thorough cooking at an appropriate temperature, observation of correct storage protocols for raw and cooked food, and adhering to proper hygiene standards when handling food, can all reduce but not eliminate incidence of such disease.

Amongst the disease-causing pathogens, Campylobacter is the most common bacterial cause of food poisoning. It is responsible for around 62,000 reported cases of illness in the UK every year; however, the estimated number of actual incidences is much higher, of the order of 600,000, as it is believed that most individuals affected by the pathogen do not seek medical assistance. The total number of campylobacter cases across the European Union states is calculated at 9 million cases per annum.

Campylobactor infection is also extremely common in retail poultry. The prevalence of Campylobacter in chicken at retail in the UK was 65.2%, based on the results from both methods combined, for the 927 samples tested (Food Survey Information sheet 04/0 9, A UK survey of Campylobacter and Salmonella contamination of fresh chicken at retail sale, UK Food Standards Agency).

Campylobacter is therefore one of the key organisms that health agencies are tackling in order to reduce levels of food-borne illness. Campylobacter can be found on meat, unpasteurised milk, and in untreated water; however there is strong evidence that poultry is the most common cause of illness.

Campylobacter are naturally present in many poultry birds, and is often found in the cecum. Transfer to the skin is thought to occur when the birds are slaughtered and eviscerated.

S It would be very desirable to kill or remove Campylobacter (and other pathogens) from meat, in particular poultry and poultry products, which are intended for human (or animal) consumption.

Brief Description of the Prior Art

A known method of disinfecting poultry carcasses involves spraying or immersing the carcasses with water containing antimicrobial agents. However, in Europe, legislation specifies that potable water must be used to wash carcasses.

GB 2105570 (A) discloses a method of reducing "weepage" in fresh-pack poultry that includes the steps of first washing the carcasses with jets of unrefrigerated water to pre-cool them and add pick-up moisture, then tumbling the carcasses to equalize the amount of pick-up moisture carried by each carcass, to reduce the general level of pick-up moisture content somewhat, draining the carcasses by gravity to remove surface moisture, and finally subjecting them to a supercold atmosphere, such as may be obtained by directing expanded liquid carbon dioxide in rapidly moving currents over the carcasses for a time to freeze-crust the carcasses.

The "freeze-crusting" shrinks the skin to squeeze out pick-up moisture from the fatty fascia layer under the skin to reduce the pickup moisture level to the allowable amount of 8%, and to remove sufficient body heat that when a carcass is then allowed to temper to an even temperature throughout, it will be below the freezing point of water, but above the -3.30 °C freezing point of the flesh, for a very short time.

The process is said to reduce seepage from the poultry products so treated.

The method is said to inhibit bacterial growth, and thus prolong shelf life. There is no disclosure of the method having any bactericidal effect, however.

US 3637405 discloses a process for packaging and preserving meats to give long shelf life and greater tenderness. The portioned or whole chicken is exposed to cold air at a temperature of -40 °C for 1 hour. The crust-frozen chicken is then held at 0 00 for at least 3 hours. The method is said to inhibit bacterial growth, and thus prolong shelf life. There is no disclosure of the method having any bactericidal effect, however.

WO 2004080189 discloses a method comprising rapidly cooling meat by exposure to S a rapid cooling temperature of no more than about -10 °C for sufficient time to provide a frozen crust on the meat and chilling the resultant crust-frozen meat by exposure of said crust-frozen meat to a chilling temperature greater than the rapid cooling temperature but no more than about +10 °C to raise the temperature of the surface of the meat and to maintain said surface at a temperature no higher than the freezing temperature of the meat for at least sufficient time to injure lethally and/or kill bacteria, is used to reduce the viability of bacteria on meat. The method is stated to have particular application in the processing of poultry meat to kill bacteria comprising the Campylobacter and/or Salmonella species.

Although the method disclosed in WO 2004080189 apparently achieves the objective of reducing the count of Campylobacter (and other bacterial species), the poultry treated according to the process cannot be sold in the EU as fresh". The sale of poultry either as whole birds or portions is regulated under the EC Poultrymeat Marketing Regulation 1906/90 (which has been incorporated into a combined EC Marketing Regulation 1234/2007). This Regulation categorizes poultry meat and only allows poultry to be marketed as fresh, frozen or quick-frozen. Fresh poultry is defined fresh poultry meat' means poultry meat not stiffened by the cooling process, which is to be kept at a temperature not below -2°C and not higher than +4°C at any time. It is not permitted to market chilled/fresh poultry which has been previously frozen and then thawed.

Studies have been conducted to determine rates of Campylobacterjejuni inactivation on poultry exposed to different cooling and freezing temperatures (Reduction of C. jejuni on the Surface of Poultry by Low Temperature (J. Food Prot, 66, 4, 2003, 652- 655)). A mixture of three strains of C. jejuni originally isolated from poultry was inoculated onto chicken wings. Storage of wings at -20 and -30°C for 72 h reduced the population of C. jejuni on wings by 1.3 and 1.8 log10 CFU/g, respectively.

Protocols were developed to superchill chicken wings with liquid nitrogen at -80, - 120, -160, and -196 °C such that the internal portion of each wing quickly reached - 3.3 °C but did not freeze. The study that conditions used in the poultry industry to superchill poultry to a nonfrozen-state internal temperature are not likely to substantially reduce Campylobacter populations on fresh products.

Summary of the Invention

S

In a first aspect, the invention provides a process for reducing the number of viable microorganisms present on the surface of meat, comprising the steps of: a) providing an untreated meat item having a surface membrane and muscle tissue, said untreated meat item having viable microorganisms on the surface membrane; b) exposing the surface membrane to cooling at a selected cooling rate until the surface membrane reaches a selected first temperature; c) optionally maintaining the surface membrane at the selected first temperature for a selected period of time; c) allowing the surface membrane to warm to a selected second temperature higher than the first temperature to give a treated meat item; characterized in that the selected rate of cooling, the selected first temperature, selected period of time and selected second temperature are selected such that the number of viable microorganisms present on the surface membrane is reduced, whilst the 13-hydroxyacyl-CoA dehydrogenase (HADH) activity of the muscle tissue is not significantly increased in the treated meat item compared with the untreated meat item.

According to a second embodiment, there is provided a meat item prepared by the process of the invention.

Summary of the Figures

Figure 1 is a graph.

Figure 2 is a graph.

Figure 3 is a graph.

Figure 4 is a graph.

Figure 5 is a graph.

Detailed Description of the Preferred Embodiments

The term "meat" as used herein refers to any form of edible (by human or animal) flesh, and includes, without limitation, pork, lamb, mutton, veal, beef, venison, fish, shellfish, and poultry. The methods of the invention are, however, particularly S appropriate for the treatment of poultry.

"Poultry" in this context includes edible birds of any type. Examples of poultry are chicken, turkey, pheasant, quail, duck, goose, guinea fowl and swan. Chicken and turkey are preferred.

The term "meat item" encompasses whole animal carcasses, both entire and eviscerated, as well as portions of meat (cuts), which comprise at least a proportion of muscle tissue. Examples of meat items are whole, eviscerated poultry carcasses, and poultry breasts, thighs and wings.

The term "untreated meat item" refers to a meat item as hereinbefore defined, which has not been subjected to the inventive process. It may (and preferably will have) undergone a number of preceding steps customary in the preparation of meat, such as stunning, slaughter, evisceration, scalding, removal of head and legs, defeathering, water or air chilling and jointing.

The term "microorganism" refers to any organism that is capable of causing illness or disease in humans or other animals. Examples of microorganisms include bacteria, fungi, archaea, and protists. Preferred microorganisms which are controlled by the methods of the invention include Campy/obacter spp., Clostridium perfringens, Escherichia co/i, Salmonella spp., Bacillus cerous, Shige/la spp., Staphylococcus aureus, Streptococcus, Listeria monocytogenes, Vibrio cholerae, Vibrio parahaemolyticus, Vibrio vulnificus, Yersinia enteroco/itica, Yersinia pseudotuberculosis, Coxiella burnetii, Bruce/la spp., Corynebacterium utcerans, and Plesiomonas shigelloides. Preferred microorganisms are Campylobacter spp. and Salmonella spp. Highly preferred are gram negative bacteria, especially Campylobacter species including Campylobacter jejuni and Campylobacter col, especially CampylobacterjejunL The term "viable microorganism" refers to a microorganism as hereinbefore defined, which is capable of causing illness or disease when ingested. It encompasses nonculturable bacteria that are in a state of very low metabolic activity and do not divide, but are alive and have the ability and become culturable once resuscitated, as well as culturable and reproducing microorganisms.

The term membrane" refers to any biological layer which covers or adheres to the S surface of the meat item to be treated, which is not muscle tissue. It includes, for example, skin (dermis and epidermis), as well as layers of fat or cartilage. It also includes the inner membrane of the body cavity of eviscerated poultry fowl.

The term "I3-hydroxyacyl-CoA dehydrogenase (HADH) activity" refers to the activity muscle mitochondrial enzyme, 13-hydroxyacyl-CoA-dehydrogenase, which is released into the intracellular fluid when the mitochondrial membranes are damaged during freezing and thawing.

r3-hydroxyacyl-CoA dehydrogenase (HADH) activity is measured using the protocol described in "The Effect of Superchilling and Rapid Freezing on the HADH Assay for Chicken and Turkey", J. Assoc. Pub!. Analysts, 2010, 38, 13-23, a modification of the method described in "Verification of Labelling of Previously Frozen Meat and Poultry by Measurement of HADH Activity" Hargin, K., .1 Assoc. PubI. Analysts, 1997, 33, 1- 46. These documents are incorporated herein by reference. The protocol is briefly summarised below.

A cuboid shaped portion of flesh with base dimensions of approximately 3Ox3Omm and a height of 20mm is used for the HADH test. For the poultry cuboid it is necessary to have six cut surfaces.

Preferably, the cuboid is taken from a predetermined depth below the surface of the surface membrane, such as between 1 and 10 mm below the surface.

Any excess surface liquid on the sample is wiped off with a tissue. The meat juice is expressed from the sample and diluted with a phosphate buffer. Aliquots of EDTA, phosphate buffer and NADH are added to diluted press juice, followed by acetoacetyl-Coenzyme A solution, in a quartz spectrophotometer cuvette. Using a U.V. spectrophotometer the rate of conversion of NADH to NAD + is measured by the rate of decrease in the absorption of the solution. The extinction at 340mm is read.

The difference between the two readings E is the decrease in absorption at 340mm.

HADH activity U/mI = V x AE! mm x dilution factor of meat juice Cxd xa Where V = volume of test mixture = 3m1 S C = extinction of co-efficient for NADH at 340nm = 6.3 d = light path of cell = 1cm a = volume of diluted meat juice = 0.lml T = time over which decrease in absorption is measured in minutes AE I mm = Extinction at start of reaction -extinction at T mm The equation becomes:-HADH activity U/mI = 3 x AEI mm x dilution factor of meat juice * 6.3 x 1 x 0.1 (* e.g. 200 for beef) The juice pressed from meat that has been frozen and thawed will therefore exhibit higher HADH activity than meat which has not boon previously frozen. Since some HADH may be released when the meat is cut during sample preparation the method is a comparative one, where the HADH activity is determined on the untreated meat item as received (X0), and then determined after treatment (X1). The ratio of the HADH activities (X1/X0) is referred to as the ft value. If the H1 value is less than 1.2, preferably less than 1.1, more preferably less than 1.05, then the HADH activity of the moat or poultry is regarded as not significantly increased.

Cooling may be achieved by any one of a number of methods. Meat items may be placed in a chamber containing air (or other refrigerant gas) held at an appropriate temperature to achieve the selected cooling rate. One or more gas circulation means (such as fans, blowers etc.) may be provided to increase the flow of cold air over the meat item, to increase the rate of cooling of the surface membrane.

Alternatively, and preferably, the surface membrane of the meat item may be cooled with a cryogen. Suitable cryogens include liquified gasses, such as liquid nitrogen, liquid air, liquid carbon dioxide and liquid argon, and solids, such as solid carbon dioxide ("dry ice", preferably in finely divided form), and combinations of these.

Liquid nitrogen is a preferred cryogen.

Cryogen may be applied to the surface membrane as a jet, spray or bath. It is S preferred that cryogen is applied as a spray. Various types of spray nozzle, such as roses or spraybars may be utilised, depending on the size and shape of the meat item to be treated.

Preferably, the cryogen is applied in combination with an impinging gas. Impinging gas serves to convey the cryogen to the surface membrane of the meat item and thus increases the rate of cooling. Suitable impinging gasses include nitrogen, air, and carbon dioxide, and mixtures of these. The pressure of the impinging gas, and the amount relative to the cryogen, are adjusted so as to achieve the selected cooling rate.

One embodiment of the process utilizes impingement type gas flow of cryogen, such as carbon dioxide or nitrogen gas, in a straight pass-through configuration. The meat item is loaded into one end of the apparatus, and is removed with the surface membrane at a selected first temperature opposite end. Oonveyors may be used to convey the meat item through the cooling apparatus and process.

In certain embodiments, the meat item is conveyed for surface cooling along a passage formed between a pair of impingement plates through which a cooling flow of a cryogen, such as carbon dioxide or nitrogen gas, is circulated to cool the surface membrane. In an alternative embodiment, the impingement plates may be disposed to one side, as opposed to being beneath the blower which circulates the cryogen. In embodiments where the meat item is a poultry carcass, the conveyer in these embodiments is a shackle conveyor.

In an alternative embodiment, a cryogenic food cabinet freezer is used. A suitable device is the CRYOLINE® OF, supplied by LINDE AG, Linde Gases Division, Seitnerstrasse 70 82049 Pullach, Germany. This embodiment is more appropriate for batch freezing and chilling processes where an in-line system is not appropriate.

In one embodiment, cryogen is supplied to the interior of a meat item by means of a spray nozzle connected to a cannula or probe. This embodiment is convenient for the internal sterilisation of the body cavity of eviscerated poultry carcasses, for

example.

The surface membrane of the meat is exposed to cooling conditions until the surface S membrane reaches the selected first temperature. The selected first temperature is chosen such that at least a proportion of the viable microorganisms present on the surface become non-viable when allowed to warm to the selected second temperature.

The prior art indicates that in order to achieve successful control of microorganisms present on the surface of meat, rapid cooling to a temperature of less than -10 °C for sufficient time to provide a frozen crust on the meat, followed by subsequent warming, is necessary. Surprisingly, the inventors have found that an extremely effective antimicrobial effect can be achieved by rapid surface chilling to temperatures well above -10 00. In addition, the prior art indicates that a frozen crust is necessary to achieve the sterilisation effect. Surprisingly, the inventors have found that providing a frozen crust is not a requirement, and indeed superior results are obtained in certain instances when the surface membrane remains unfrozen.

Preferably, the selected first temperature is below 2 °C. More preferably, the selected first temperature is below 1 °C. More preferably, the selected first temperature is below 0.5 00. Still more preferably, the selected first temperature is below 0 00. Still more preferably, the selected first temperature is below -0.5 °C.

Preferably, the selected first temperature is above 5 00. More preferably, the selected first temperature is above -4 00. Still more preferably, the selected first temperature is above -3.5 °C. Still more preferably, the selected first temperature is above -3 °C. Still more preferably, the selected first temperature is above -2.5 °C.

Most preferably, the selected first temperature is above -2 00 Utilising a temperature above -2 00 has the advantage that meat treated according to the process fulfils the requirement that fresh poultrymeat' is to be kept at a not below -2°C at any time Preferably, the selected first temperature being in the range of between -5 00 and 2 °C More preferably, the selected first temperature is between -3 °C and 1 00. Still more preferably, the selected first temperature is between -2 °C and 0.5 00 -10-The selected first temperature and selected second temperature refer to temperature of the surface as measured by infrared thermometer or a probe inserted within or just below the membrane.

S Prior to exposure of the surface membrane to the cooling step of the invention, the meat item may be at ambient temperature (for example, between 20 °C and 29 °C), or it may be (and preferably is) pre-chilled to below ambient temperature. In one embodiment, the meat item is pre-chilled to a temperature below ambient temperature, such that the temperature of the meat item is substantially uniform throughout the meat item. Preferably, the meat item is pre-chilled to below 15 DC, more preferably to below 10 °C, still more preferably to below 5 °C, still more preferably to below 2 00.

It may be more convenient, however, to carry out the process of the invention on meat items which arrive from the preceding steps in the processing plant without a preliminary step of refrigeration.

The cooling rate is selected such that the desired temperature reduction of the surface membrane occurs sufficiently rapidly that no substantial change in the temperature of the underlying muscle occurs. The skilled person will be able to determine a suitable cooling rate for each particular type of meat item.

In a particularly preferred embodiment, the meat item is cooled by reducing the ambient temperature (i.e. the temperature of the atmosphere surrounding the meat item) at a rate of between 0.1 DC/s and 5 0C/s more preferably at a rate of between 0.2 °C/s and 3 °C/s, most preferably at a rate of between 0.5 °C/s and 3 00/s.

Preferably, the ambient temperature of the atmosphere surrounding the meat is cooled to a temperature of between -10 DC and -150 DC more preferably between -20 °C and -100 °C, still more preferably between -30 °C and -90 00.

Preferably, the meat item is exposed to the surface cooling conditions for as short a period of time as feasible. This ensures that the temperature gradient through the meat item is high, and a large differential between the temperature of the surface membrane and the temperature of the underlying muscle is maintained. -11 -

Optionally, and preferably, the surface membrane of the meat item is maintained at the preselected temperature for a period of time. This period of time is selected such that insufficient heat is transferred from the muscle meat to cause a significant increase in the activity of HADH.

S

In one preferred embodiment, the cooling is achieved by use of a refrigerated tunnel having a predetermined temperature profile. The rate of passage of the meat items through the tunnel is adjusted so as to obtain the correct rate of cooling. This embodiment is particularly convenient when the process of the invention is part of the production line for the preparation of meat products.

Preferably, the surface membrane of the meat item is maintained at the selected first temperature for between 30 seconds and 20 minutes, preferably between 1 minute and 10 minutes, more preferably between 1.5 minutes and 7 minutes, most preferably between 2 and 6 minutes.

Alternatively, the meat item need not be maintained at the selected first temperature, but on reaching the selected first temperature may instead be warmed or allowed to warm to the selected second temperature.

The selected second temperature is higher than the selected first temperature. The differential between the selected first and selected second temperature is selected such that the number of viable microorganisms is reduced, and also to fit efficiently with subsequent steps in the processing of the meat item. Preferably, the selected second temperature is above -1 °C. Preferably, the selected second temperature is below 20 °C, more preferably below 15 °C, still more preferably below 10 00, still more preferably below 5 00, most preferably below 4 00. Very preferably, the selected second temperature is between -1 °C and 4 °C. Maintaining the temperature not higher than +4°C at any time fulfils the requirement for fresh poultry meat under European legislation.

Quantitative assessment of the number of viable microorganisms present on surface membrane is carried out in accordance with appropriate protocols. For example, Campylobacter is quantified according to ISOITS 10272-2:2006(E) "Microbiology of food and animal feeding stuffs -Horizontal method for detection and enumeration of Campylobacter spp. -Part 2: Colony-count technique". Other microorganisms may be quantified using different techniques. The term "number of viable -12-microorganisms" will be understood by the skilled person as referring to the number of such microorganisms present per unit surface area of surface tissue.

The rate of cooling, the selected first temperature and the selected second S temperature are chosen such that the reduction in the number of viable microorganisms present on the surface of the meat observed is at least statistically significant within the limits of the quantification method used. Preferably, at least a log (ten-fold) reduction in the number of microorganisms present is achieved. More preferably, at least a 2-log (hundred-fold) reduction in the number of microorganisms present is achieved.

Preferably, the R1 of the HADH activity in the treated item is less than 2. more preferably less than 1.5, more preferably less than 1.2, more preferably less than 1.1.

Because the muscle tissue remains largely unaffected by the treatment of the skin (or other surface membrane) according to the present invention, the meat item retains the organoleptic and nutritional qualities of fresh meat.

Subsequent to treatment with the inventive process, the treated meat items may be subjected to any further processes customary for the treatment of fresh meat, such as jointing, chilling (air and water chilling are contemplated), and packing or wrapping.

Preferably, the inventive process is one of the last steps on the production line prior to packing to prevent the possibility of recontamination of the treated meat item.

The process may also include further process steps such as curing, smoking, salting, pickling, or cooking.

Examples

The process involved using a CRYOLINE® CF unit which has a temperature control system with an ability to inject cryogenic gases into the unit for cooling purposes.

The cabinet has an inner chamber into which slaughtered poultry carcases were hung by their legs, which allowed the neck skin to hang clear of the bird, and the body cavity entrance to be open. -13-

The unit was set to a temperature that allowed rapid cooling of the skin of the bird and other outer or exposed membranes such that a temperature of below -2 °C was achieved, with no parts going below -3.8 °C. This was achieved via the use of a cryogenic gas spray bar which introduced liquid nitrogen into the cabinet, and a circulation fan able to deliver impingement, or rapid temperature exchange, on the exposed membranes.

The flesh of the bird was not frozen, but the skin and membranes underwent rapid cooling. This was followed by removal from the unit, and the carcass was then allowed to rise back in temperature to the normal chilled holding range of -1 °C to +4 DC.

This process was designed to rapidly cool the surface membrane and campylobacter bacteria present upon the carcass surfaces, and to render them into a cold tempered state, similar to that seen just before the product passes through the latent heat phase, thus avoiding full freezing of the poultry carcasses. The rapid cold shock administered to the bacteria on the bird renders them damaged such that during the temperature rise back to normal chill temperatures the Gampylobacter bacteria are severely damaged or killed, rendering therm unable to create infection.

The birds were rapidly chilled in the cabinet and this was completed satisfactorily without the freezing of the muscle units of the birds, in times from around 30 seconds up to a dwell time of five minutes, depending upon carcass size and ingoing temperature.

Example 1

The cabinet was set to a temperature of -SO °C (other temperatures delivered the same result but took more or less timer to deliver the cold tempered state).

In some cases the campylobacter bacteria were fully destroyed, and in all cases in excess of a two log reduction was delivered. This damage and destruction of Gampylobacter is delivered by faster and simpler means than any previous process.

Table 1 indicates the Gampy/obacter count achieved after treatment of naturally infected turkey carcasses according to this protocol. -14-

Figures 1 to 5 indicate the temperature profile of the surface of turkey carcasses exposed to rapid chilling conditions at i) the surface and ü) 5mm depth penetration of the wing and breast. -15-

Table 1

Sample Temperature/ SURFACE SURFACE Campylobacter count No Time TEMP °C IN TEMP °C Cf u/g

OUT

1 -80°C 2 mins 1-1.5°C 0.5°C 0.00E+O0 2 -80°C 2 mins 1-1.5°C 0.5°C 0.OOE+00 3 -80°C4mins 1-1.5°C -1.5°C 0.OOE+00 4 -80°C4mins 1-1.5°C -1.5°C 0.OOE+00 -80°C 6 mins 1-1.5°C 0.3 0.OOE+00 to -0.3°C 6 -80°C 6 mins 1-1.5°C 0.3 0.OOE+00 to -0.3°C 7 -80°C 5 mins 1-1.5°C -0.2°C 0.OOE+00 8 -80°C 5 mins 1-1.5°C -0.2°C 0.OOE+00 9 -80°C 5 mins 1-1.5°C -1.1 0.OOE+00 to -1.9°C -80°C 5 mins 1-1.5°C -1.1 0.OOE+00 to -1.9°C 11 CONTROL 1.OOE+02 12 CONTROL 5.OOE-i-01 13 CONTROL 5.OOE+01 14 CONTROL 3.OOE+02 CONTROL 2.OOE+01 16 CONTROL 1.OOE+01 17 CONTROL 2.OOE+02 18 CONTROL 1.OOE+01 19 CONTROL 1.OOE+01

Example 2

All birds were pre chilled to 4 °C as testing was completed externally. They were treated for between 30 seconds and for 2 minutes under the conditions used for Example 1. The reduction in campylobacter count is shown in Table 2. -16-

Table 2

____ _____________ Dayl Day7 :1111111 It: 11 a -a -° a a E 2 2 rE 0 0(0 Ow W 0(0 0(0 __________ C 00 00 4 00 00 i chicken control 710,000 500 300 12,000,000 <10 <10 2 chicken control 3,200,000 370 370 25,000,000 <10 <10 3 chicken Control 23,000,000 460 460 12,000,000 90 4 Chicken Control 1,900,000 210 210 16,000,000 <10 <10 s chicken Control 140,000 60 60 13,000,000 <10 <10 6 Chicken Control 380,000 490 490 14,000,000 <10 <10 7 Chicken Control 350,000 830 830 16,000,000 340 8 chicken Control 1,100,000 80 <10 21,000,000 <10 <10 11 Chicken Treated 130,000 <10 <10 12,000,000 <10 <10 12 chicken Treated 84,000 <10 <10 14,000,000 <10 <10 13 Chicken Treated 660,000 <10 <10 16,000,000 <10 <10 14 chicken Treated 140,000 <10 <10 14,000,000 <10 <10 Chicken Treated 140,000 <10 <10 12,000,000 <10 <10 16 Chicken Treated 740,000 110 <10 12,000,000 <10 <10 17 Chicken Treated 450,000 <10 <10 14,000,000 <10 <10 18 Chicken Treated 80,000 <10 <10 13,000,000 <10 <10 19 Chicken Treated 75,000 <10 <10 13,000,000 <10 <10 Chicken Treated 120,000 <10 <10 14,000,000 <10 <10 21 Turkey Control 26,000 50 <10 13,000,000 <10 <10 22 Turkey Control 58,000 300 60 16,000,000 50 23 Turkey Control 26,000 140 84 12,000,000 <10 <10 24 Turkey Control 51,000 300 240 19,000,000 60 27 Turkey Treated 17,000 10 10 21,000,000 10 28 Turkey Treated 17,000 <10 <10 23,000,000 <10 <10 29 Turkey Treated 15,000 20 20 16,000,000 <10 <10 Turkey Treated 35,000 90 90 18,000,000 <10 <10 31 Turkey Treated 9,900 50 30 19,000,000 20 32 Turkey Treated 52,000 90 18 23,000,000 20 _______

Claims (14)

1. -I--CLAIMSA process for reducing the number of viable microorganisms present on the surface of meat, comprising the slops of: a) providing an untreated meat item having a surface membrane and muscle tissue. said untreated meat tern having viable microorganisms on the surface membrane; h) exposing the surface membrane to coohng at a selected coohng rate unth the surface membrane reaches a selected first temperature; c) optionaUy maintaining the surface membrane at. the selected firsi temperature for a selected period of time; c) sHowing the surface membrane to warm to a selected second temperature higher than the first temperature to give a treated meat tern; characterized in that the selected rate of cooling, the selected first temperature selected period of lime and selected second temperature are selected such that the number of viable microorganisms present on the surface membrane is reduced, whilsi the B-hydroxyacyl-CoA dehydrogenase (HADH) activity of the muscle tissue is not significantly increased in the treated meat tern compared with the untreated meat item.
2. 2. A process according to claim 1 wherein the meat item is selected from a whole poultry carcass, optionally eviscerated.
3. 3. A process according to claim 1 wherein the meat item is a pouliry portion.
4. 4. A process according to any preceding claim wherein the selected first temperature is between -5 °c and 2 °C.
5. 5. A process according to any preceding claim wherein the said cooling is achieved by exposing-the surface membrane to a cryogen.
6. 6. A process according to claim 5 wherein the cryogen is selected from liquid nitrogen, liquid carbon dioxide and liquid air. -18-
7. 7. A process according to any one of daims 5 and 6 wherein the cryogen is apphed ri combination wIh an impinging gas.
8. 8. A process according to any preceding daim wherein the seecfed second temperature is b&ow 4 °C.
9. 9. A process according to any preceding claim wherein the microorganisms comprise at east Campylohacter species.
10. 10. A process according to any preceding daim comprising further steps customary in the treatment of fresh meat items.
11. 11. A process according to any preceding claim comprising at least one further step of curing, smoking, salting, picking, or cooking the treated meat tern.
12. 12. A process substantially as described herein with reference to the examples.
13. 13. A treated meat item obainabe according 10 any one of damns I to 11.
14. 14. A treated meat item substantiafly as described herein with reference to the exampes.Amendments to the claims have been 19 fHed as follows:CLAIMS1. A process for reducing the number of viable microorganisms present in the body cavity of an eviscerated poultry carcass, comprising the steps of: a) providing an untreated poultry carcass having a surface membrane and muscle tissue, said untreated poultry carcass having viable microorganisms on the surface membrane of a body cavity; b) exposing the surface membrane of the body cavity to a cryogen by means of a spray nozzle connected to a cannula or probe; c) allowing the surface membrane to warm to give a treated meat item; characterized in that the number of viable microorganisms present on the surface membrane is reduced, whilst the 13-hydroxyacyl-CoA dehydrogenase (HADH) activity of the muscle tissue is not increased by a factor of more than 2 in the treated meat item compared with the untreated meat item.LI') 2. A process according to claim 1 wherein the cryogen is selected from liquid nitrogen, liquid carbon dioxide and liquid air.3. A process according to claim 2 wherein the cryogen is applied in combination (Q with an impinging gas. (44. A process according to any preceding claim wherein the microorganisms comprise at least Campylobacter species.5. A process according to any preceding claim comprising at least one further step of curing, smoking, salting, pickling, or cooking the treated meat item.