DK202001012A1 - A flash-heat treatment method for conducting thermal shock-treatment of meat products - Google Patents

Abstract

The present invention relates to a system comprising an especially designed flash-heat treatment system for conducting thermal shock-treatments of vacuum-packed meat products, and a method for conducting thermal shock-treatments for reducing surface contamination of vacuum-packed meat products.

Description

DK 2020 01012 A1 1 A FLASH-HEAT TREATMENT SYSTEM AND A METHOD FOR CONDUCTING THERMAL SHOCK-TREATMENT OF MEAT PRODUCTS

TECHNICAL FIELD The present invention relates to a system comprising an especially designed flash- heat treatment system for conducting thermal shock-treatments of vacuum-packed meat products, and a method for conducting thermal shock-treatments for reducing surface contamination of vacuum-packed meat products.

BACKGROUND ART Heat treatment is used to in the food industry to avoid multiplication of bacteria during storage and transportation of products. Pasteurization leads to increased food safety for the consumer, increased shelf life of the product and at the same time reduces the need for applying preserving additives acting as growth inhibitors for bacteria.

Inactivation of bacteria as early as possible in meat processes, where bacterial count is small, is preferred. Microbes such as spores of Clostridium botulinum, Listeria monocytogenes, and other heat resistant bacteria are notoriously difficult to inactivate.

Also, due to formation of a severe toxin, growth of C. botulinum must be avoided, especially in vacuum packed and chilled meat products. Additionally, bacteria responsible for spoilage of meat products, especially psychotropic bacteria capable of growing at low storage temperatures in vacuum and with little or no access to oxygen, must be controlled by the pasteurisation process.

Conventional decontamination/sterilisation methods are usually performed at 121°C for e.g. 15 to 30 minutes. These procedures completely alter the nature of the meat product, leaving it fully or partially cooked, and are therefore not well suitable for use on a wide range of products.

In this respect, WO2001026488, US2005123435 and US20120258228 describe examples of conventional autoclaving methods using especially designed autoclaves.

Some pasteurisation procedures utilize micro-wave heat treatment systems using short wavelength microwaves. These systems suffer from the fact that it is very difficult to avoid cold spots on the surface of the items being auto-clavated. These cold spots will act as sanctuaries for microorganisms.

In this respect, US5066503, US5389335, US2007065551 and WO2009029731 describe examples of methods of pasteurizing or sterilizing foodstuffs utilizing microwaves.

Finally, WO2012067626 describes an example of a method for treating a surface of intact meat while leaving a portion of an interior of the piece of intact meat uncooked,

DK 2020 01012 A1 2 which method includes e.g. thermal treatment, irradiating the surface with ionizing or non- ionizing radiation, and treating the surface with an antimicrobial substance.

However, none of these techniques effectively ensures a rapid heat treatment of the product surface exclusively. There is a need for reliable pasteurisation methods, capable of reducing the number of spores, viable pathogenic bacteria, and spoilage bacteria, and at the same time are gentle to the meat product.

SUMMARY OF THE INVENTION Pasteurisation is achieved by applying heat to the product, and it is, within certain limits, the combination of temperature and time that represent a major factor for an effect. However, prolonged heat treatment may affect the characteristics of the meat products and negatively influence the visual appearance (e.g. colour), texture and taste. Therefore, the applied level of heat treatment to any meat product will often be a balance between allowing for a reasonable product shelf life and, simultaneously, not compromising the food palatability.

A prominent feature of the present invention resides in the use of an air pressure supply device/back pressure channel (i.e. a pressure-on/pressure off channel), for adjusting the temperature, thereby determining the treatment time. This ensures a rapid heat treatment of the product surface exclusively. This feature also allows for a safe control of the water flow to/from the external water reservoir/hydrophore and the heat treatment chamber.

In its first aspect, the invention provides a system comprising an especially designed system, as described in the claims, intended for conducting thermal shock- treatments of vacuum-packed meat products.

The system of the invention is designed to provide an instant heat-shock following treatment of meat cut products with hot water in a pressurized chamber. This chock- treatment, directed exclusively to the surface of vacuum-packed cut meat products, increases the effect of the inactivation compared to slow heating. In pilot experiments, filling of the treatment chamber and covering the products with pressurised hot water takes approximately 7 seconds.

In another aspect, the present invention provides a method for rapid surface decontamination of vacuum-packed meat products, as described in the claims. The present invention may be performed using pressurized hot water at a temperature of above 120°C and a pressure of above e.g. 2 bar, applied over a period for as short as 0.5 minutes.

The method of the invention is particularly useful as a pre-treatment step or as a post-treatment step to conventional meat processing, for use e.g. in connection with repacking of large, spherical, cut meat products.

DK 2020 01012 A1 3 Other objects of the invention will be apparent to the person skilled in the art from reading the following detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is further illustrated by reference to the accompanying drawing, in which: Fig. 1 shows the essential elements of the system of the invention, i.e. Heat treatment chamber (2); Door for introduction and removal of meat products (2A); Aqueous space of the treatment chamber (2B); Air space of the treatment chamber (2C); Water level of treatment chamber (2D); Pressure gauge/manometer (2E); External hot water reservoir/hydrophore (3); Aqueous space of water reservoir (3A); Air phase of water reservoir (3B); Water level of reservoir (3C); Inter-connection channel/flow-valve (4); Channel for pressure supply/back pressure channel (Pressure-on/pressure off channel) (5); Treatment chamber pressure-off valve/excess-pressure valve (5A); Water supply channel (6); Reservoir pressure-off valve/excess-pressure valve (6A); Energy supply/heating device (7); Vacuum-packed meat products (8); Drain for draining excess water from the heat treatment chamber (2) (9); Turbidity meter/turbidometer/nephelometer (9A); Fig. 2 shows a graphic presentation of a phase diagram (temperature-pressure) for water, showing the pressure/temperature ranges in which the process of the invention should be performed, i.e. at temperatures of above approximately 120°C, and a pressure of above approximately 2 bar; Fig. 3 shows a graphical presentation of the varying temperature/pressure levels (of from about 20°C to about 135°C, of from about 1 to about 7.5 bar) and over time (of from 0 to 700 seconds) during two heat treatment cycles performed according to the method of the invention; Fig. 4A shows another embodiment of the system of the invention: Heat treatment chamber (2), Aqueous space of treatment chamber (2B), Air phase of treatment chamber (20), Treatment chamber pressure gauge/manometer (2E), Grate for supporting the meat product (2F), Water level indicator (2G), External hot water reservoir/hydrophore (3), Aqueous space of water reservoir (3A), Air phase of water reservoir (3B), Inter-connection channel/flow-valve: Pressurised hot water supply to treatment chamber (4A), Pressurised hot water reflux to reservoir or to drain (4B), Channel for pressure supply/back pressure channel (Pressure-on/pressure off channel) (5), Treatment chamber pressure-off valve/excess-pressure valve (5A), Reservoir pressure-off valve/excess-pressure valve (6A), Reservoir safety valve/excess-pressure valve (6B), Reservoir pressure

DK 2020 01012 A1 4 gauge/manometer (6C), Energy supply/heating device (7), Vacuum-packed meat products (8), and Drain for draining excess water from the heat treatment chamber (9); Fig. 4B shows yet another embodiment of the system of the invention: Heat treatment chamber (2), Aqueous space of treatment chamber (2B), Air phase of treatment chamber (2C), Treatment chamber pressure gauge/manometer (2E), Grate for supporting the meat product (2F), Water level indicator (2G), External hot water reservoir/hydrophore (3), Aqueous space of water reservoir (3A), Air phase of water reservoir (3B), Inter-connection channel/flow-valve: Pressurised hot water supply to treatment chamber (4A), Pressurised hot water reflux to reservoir or to drain (4B), Channel for pressure supply/back pressure channel (Pressure-on/pressure off channel) (5), Treatment chamber pressure-off valve/excess-pressure valve (5A), Reservoir pressure-off valve/excess-pressure valve (6A), Reservoir safety valve/excess-pressure valve (6B), Reservoir pressure gauge/manometer (6C), Energy supply/heating device (7), Vacuum-packed meat products (8), Drain for draining excess water from the heat treatment chamber (9), and Heat exchanger (10); Fig. 5 shows an example of an industrial design of the system of the invention: Heat treatment chamber (2), External hot water reservoir/hydrophore (3); Drain(9) for draining excess water from the heat treatment chamber (2), and Processing operator (12); Figs. 6A-6C illustrates different stages of the meat products contemplated according to the process of the invention: Fig. 6A: Meat product with germ on its surface; Fig. 6B: Vacuum-packed meat product with germ on its surface, but underneath the foil, and where the foil remains tight and envelops the product; and Fig. 6C: Vacuum-packed meat product with germ on its surface, but underneath the foil, and where water on the surface of the meat product has started boiling, allowing the foil to expand, as a consequence of the pressure inside the heat treatment chamber (2) being too low.

DETAILED DISCLOSURE OF THE INVENTION The system of the invention In its first aspect, the present invention provides a system for conducting a thermal shock-treatment of one or more vacuum-packed meat products. The system (1) of the invention may be characterised by comprising the following essential elements: a. a heat treatment chamber (2), which heat treatment chamber is dimensioned to enclose the vacuum-packed meat products (8) in question, and capable

DK 2020 01012 A1 of closing tightly and withstanding a large internal overpressure, e.g. of 2-6 bar, and which heat treatment chamber (2) comprises: al. a gate/door (2A) for the supply and withdrawal of one or more vacuum- packed meat products (8); 5 a2. an air pressure supply device/back pressure channel (5), for delivering an overpressure, e.g. of 3-6 bar, sufficient to withstand the corresponding pressure (of typically 3-6 bar) in the external hot water reservoir (3), which air pressure is adjustable and allows for regulating the water flow between the external water reservoir/hydrophore (3) and the heat treatment chamber (2); a3. and which heat treatment chamber (2) is connected to an inter-connection channel (4), for implementing a water flow between, i.e. to and/or from, the external water reservoir/hydrophore (3) and the heat treatment chamber (2), i.e. by supplying and discharging of the pressurised, hot water; and b. an external hot water reservoir/hydrophore (3), for storing and supplying pressurized hot water, which external hot water reservoir/hydrophore (3) comprises: bl. a water supply channel (6), which allows for water supply to the external hot water reservoir/hydrophore (3); b2. an energy supply/heating device (7), which can provide sufficient energy to maintain the intended pressure/temperature level; b3. and which external hot water reservoir/hydrophore (3) is also connected to the inter-connection channel (4), for implementing a water flow between, i.e. to and/or from, the external water reservoir/hydrophore (3) and the heat treatment chamber (2), i.e. by supplying and discharging of the pressurised, hot water.

A prominent feature of the present invention resides in the use of an air pressure supply device/back pressure channel (i.e. a pressure-on/pressure off channel) (5), for adjusting the temperature, thereby determining the treatment time. This feature also allows for a safe control of the water flow to/from the external water reservoir/hydrophore (3) and the heat treatment chamber (2).

It is currently believed that a heat treatment temperature in the range of from about 120 to about 150°C will be sufficient for most surface decontamination purposes. For obtaining such temperatures, a pressure of from about 3 to about 5 bar may be needed (see Fig. 2).

The current design goals revolve around reaching temperatures of up to 140°C (3.6 bar absolute pressure) with submersion times of 30-300 seconds in the treatment chamber. This is not considered a maximum temperature, and the treatment temperature can increase with increased pressure. The maximum possible temperatures

DK 2020 01012 A1 6 depend on pressure vessel regulations and practicalities revolving heat source temperature, etc.

Therefore, the system of the invention comprises an inter-connection channel (4), for implementing a water flow to/from the external water reservoir/hydrophore (3) and the heat treatment chamber (2), which inter-connection channel (4) can supply and discharge of the necessary pressurised, hot water.

In one embodiment, the inter-connection channel (4) consists of two channels, i.e. an input/supply channel (4A) and an output/diversion channel (4B), as shown on Figs. 5A and 5B.

In view of the high pressure applied during processing of the meat products, the system should be equipped with a safety valve.

In one embodiment, the air pressure supply device/back pressure channel (5) constitute a heat treatment chamber pressure-on and/or pressure off channel (5), i.e. also include excess-pressure valve.

In another embodiment, the heat treatment chamber (2) comprises a separate heat treatment chamber pressure-off valve/excess-pressure valve (5A).

In analogy herewith, the the external hot water reservoir/hydrophore (3) may also comprise a pressure-off valve/excess-pressure valve (6A).

In the interest of securing a sufficient supply of pressurised, hot water, the system of the invention may also comprise one or more water level meters.

In one embodiment, the system of the invention comprises a treatment chamber water level indicator (2G).

In another embodiment, the system of the invention comprises a water reservoir water level of reservoir (3C).

Another prominent feature of the invention resides in preserving maximal energy by reuse of hot water. This may take place by reflux of the process-water from the heat treatment chamber (2) after concluded processing. Reflux of the process-water from the heat treatment chamber (2) back to the water reservoir/hydrophore (3) may take place via the inter-connection channel (4).

In one embodiment, reflux of the process-water from the heat treatment chamber (2) back to the water reservoir/hydrophore (3) may take place via a separate channel (4B).

Another way of conserving energy from the system of the invention may be by help of a heat exchanger (10), that can extract the energy from the process-water when itis being refluxed from the from the heat treatment chamber (2).

Therefore, in one embodiment, the system of the invention also comprises a heat exchanger (10), capable of extracting the energy from the from the process-water when it is being refluxed from the from the heat treatment chamber (2).

DK 2020 01012 A1 7 In a further embodiment, however, the process-water is neither being refluxed back to the water reservoir/hydrophore (3), nor being subjected to the heat exchanger (10) but is simply diverted to a drain (9). This drain may lead water to the ordinary sewer. Heat processing of the vacuum-packed meat products (8) involves the risk of the vacuum packing being spoiled, thereby allowing leakage of its content, or parts hereof. Although no major microbiological issue to the decontamination process, leakage of the vacuum-packed meat products (8) may be monitored for the sake of detecting and separating leaky products from the production. Leakage of the vacuum-packed meat products (8) may cause the process water becoming turbid and may possibly be detected by a turbidity meter. Therefore, in a further embodiment, the system of the invention may also comprise a turbidity meter/turbidometer/nephelometer (9A) for checking for turbid water, for control of leaks from the vacuum-packed meat products (8). This turbidity meter/turbidometer/nephelometer (9A) may preferably be placed in connection to the drain (9), that drains excess water from the heat treatment chamber (2). The water for use in the system of the invention and supplied by the water supply channel (6), may originate from ordinary tap-water. The pressure and temperatures applied during processing in the system of the invention places great demands on the equipment. The material from which the system is made must be able to withstand high temperatures and at the same time a very high pressure. Useful materials include steel compositions, and in particular stainless-steel compositions. In a further embodiment, the heat treatment chamber (2) of the system of the invention may comprise an interior non-adhesive surface for preventing packaging material of being damaged during and after the heat treatment, e.g. a net made from Teflon or similar material The material of the heat treatment chamber (2) also should allow for rapid heating and/or cooling of the treatment chamber. Therefore, the heat treatment chamber (2) may comprise equipment for local heating/cooling of the treatment chamber. This may be achieved by supplying the heat treatment chamber (2) with a dedicated heating/cooling device, e.g. by enclosing the treatment chamber in a heating/cooling jacket. Therefore, in a further embodiment, the heat treatment chamber (2) comprises a heating device and/or a cooling device (11).

The heat treatment chamber In the interest of saving energy, the heat treatment chamber (2) of the invention should be dimensioned according to the batch size in question. Therefore, the heat

DK 2020 01012 A1 8 treatment chamber should the able to enclose the one or more vacuum-packed meat products (8) in question, while leaving space for a sufficient circulation of the pressurised, hot water during the processing. Therefore, in one embodiment, the haat treatment chamber (2) comprises a grate (2F) for supporting the mest product, and for securing an adequate water distribution around the meat products {8). For securing adequate water distribution around the meat product these products may be placed in one layer only. Preliminary thermodynamic calculations indicating the approximations of relevant parameters in terms of envisioning equipment size are presented in Table 1.

Table 1 | treatedpers. || — massjkg] | massikgl | nominal operation ye 2 | se | 4m | 16 | The method of the invention In another aspect, the invention provides a method for rapid decontamination of the surface of a vacuum-packed meat product by performing a thermal shock treatment to the surface of the meat product. The method of the invention is based on the use of the above described system. The method of the invention may be regarded an additional process, used e.g. in connection with repacking of large, spherical, cut meat products, and the method may in particular be used as a pre-treatment step, e.g. for low temperature cooking, e.g. sous vide processing, or before brine injection, in order to minimize contamination of the interior of the product, or as a post-treatment step, e.g. for fully-processed/ cooked meat products after re-packaging, in order to minimize risk of recontamination. The method of the invention may be characterised by comprising the subsequent steps of: a. vacuum-packing the meat product (8) in a heat resistant, food-grade material: b. placing the vacuum-packed meat product (8) in a heat treatment chamber (2), dimensioned to enclose the vacuum-packed meat products (8) in question, and capable of withstanding a large internal overpressure, e.g. of 2-6 bar; ¢. initiating the build-up of a back pressure, e.g. of 3-5 bar, in the heat treatment chamber (2) corresponding to the pressure, of e.g. 2-5 bar, in the external hot water

DK 2020 01012 A1 9 reservoir/hydrophore (3), by gently opening the channel for pressure supply/back pressure channel/pressure-on channel (5), for a subsequent controlled supply of pressurised, hot water; d. initiating the supply of pressurised, hot water from the external water reservoir/hydrophore (3) to the heat treatment chamber (2) by gently opening the inter- connection channel/flow-valve (4), and gently regulating the transport/filling time by adjusting the back pressure through the channel for pressure supply/back pressure channel (5); e. initiating thermal shock treatment of the vacuum-packed meat product (8), by maintaining the desired pressure/temperature, e.g. 3-5 bar/120-140°, for the desired time-period, e.g. 30-300 seconds: f. discharging the pressurised, hot water from the heat treatment chamber (2) back to the external water reservoir/hydrophore (3), or by discharge to a drain (9), by gently increasing the back pressure, to e.g. 6 bar, through the channel for pressure supply/back pressure channel (5); g. when emptied, maintaining the pressure in the heat treatment chamber (2) until the meat product (8) has cooled sufficiently in order to prevent boiling of water inside the vacuum pack; and h. decreasing the pressure within the heat treatment chamber (2) by gently opening the channel for pressure supply/back pressure channel (5) and release of the over-pressure, and removal of the heat-treated meat product (8).

The method of the invention may be carried out as an additional process in connection with repackaging of meat products, and optionally in a combination with other heat treatment processes.

In one embodiment, the method of the invention further comprises the step of subjecting the surface decontaminated meat product of step b to a sous vide process, e.g. at 55-85 C for 1-72 hours.f The actual pressure/temperature setting may depend on the equipment used and on the tolerability of the packaging material.

A prominent feature of the present invention resides in the use of an air pressure supply device/back pressure channel (i.e. a pressure-on/pressure off channel) (5), for adjusting the temperature, thereby determining the treatment time. This feature also allows for a safe control of the water flow to/from the external water reservoir/hydrophore (3) and the heat treatment chamber (2).

In this respect it is of utmost importance that the meat product remains tightly enclosed by the foil of the vacuum pack. This is controlled by carefully adjusting the pressure inside the heat treatment chamber during processing, and especially during

DK 2020 01012 A1 10 termination of the process and cooling of the vacuum-packed meat product (8), where it is important that the water inside the vacuum-pack never boils and causes the foil to rise.

It is currently believed that a heat treatment temperature in the range of from about 120 to about 150°C will be sufficient for most surface decontamination purposes.

For obtaining such temperatures, a pressure of from about 3 to about 5 bar may be needed (see Fig. 2). Such settings can lead to process times of between 0.5 to 5 minutes, depending on the product chosen and the intended purpose.

After being treated according to the method of the invention, the decontaminated meat product may e.g. be determined for storage, e.g. at a storage temperature of about 0 to 8°C, or the product may e.g. be determined for being subjected to a subsequent sous vide process, where a temperature of about 55 to 80°C may be desired.

The system may also comprise further meat processing, such as sous vide bath(s), multi needle injector(s) device(s) and/or mechanical tenderizer(s).

The meat products The meat product to be subjected to the method of the invention may in particular be a meat product having a non-processed (raw) interior, or it may be an already fully processed meat product with no need for further heat-treatment in the core of the product.

The meat product processed according to the invention shall be properly vacuum- packed in a heat resistant, food-grade material.

The meat product to be subjected to the method of the invention may in particular be a meat product having a non-processed (raw) interior, and may be of beef or poultry, e.g. pork neck or pork loin.

Vacuum-packing and heat-resistant materials The meat product processed according to the invention shall be properly vacuum- packed in a heat resistant, food-grade material.

Heat resistant, food-grade materials for use according to the invention include a plastic boilable pouch like CN400 heat stable cooking bags of size 230x500 mm, Sealed Air, Herlev, made of a film laminate PETP 12/PEP LDPE 75.

EXAMPLES The invention is further illustrated with reference to the following examples, which are not intended to be in any way limiting to the scope of the invention as claimed.

DK 2020 01012 A1 11 Example 1 Time to a 6-log reduction A challenge trial has been performed, to document the effect of thermal shock treatment with Flash autoclave using 130°C hot water. This experiment showed that, at 130°C, C. botulinum spores can be eliminated from a raw meat surface nine times faster than in 90°C hot water.

The challenge experiments were performed on meat samples inoculated with C. botulinum spores and Listeria monocytogenes, vacuum-packed and treated with a 130°C flash autoclave, using a 90°C water bath as reference method.

Table 2 Calculated D-values (with standard deviation} and time to obtain a 6-log reduction for different target bacteria and spores using water at 130%C =... + {1 7 logimin] ron [omens | ow | os | 20 Example 2 Pathogen challenge test The study was divided into 6 batches, batch 1-4 were a pathogen challenge study, and batch 5-6 were a shelf life study. The batches were treated over a period of & days.

Pork necks with pH 5.8-6,0 were collected on the same day at a Danish abattoir and stored at 0% until sample preparation. Pork necks were trimmed and cut into three samples each weighing 500 g + 10 g with a thickness of approx. 8 cm. The samples were marked as 1, 2, and 3 for randomisation purposes, Samples for batch 1-4 were dried in a LAF bench {Laminar Flow Cabinet) for 15 minutes, and 1 mi spore cocktail of non-proteolytic (non-toxigenic and gas producing} C. botulinum strains (DMRICC 3760PX, 3778 PX, 3779PX, and 3780PX) was added to the samples, which corresponds to about 105 spores per cm? of the meat surface.

DK 2020 01012 A1 12 The samples were vacuum-packed in plastic boilable pouch (CN400 heat stable cooking bags of size 230x500 mm, Sealed Air, Herlev) made of a film laminate PETP 12/PEP LDPE 75.

Thermal shock treatment Prior to treatment TrackSense Pro Data Loggers (Ellab, Hillerod) were fixed on the top wire mesh in order to record temperature and pressure during treatment. The equipment was heated without any sample in the chamber and two water level measurements were performed to ensure sufficient coverage of the sample during treatment.

Half of the samples were shock treated in order to achieve a 6-log?? reduction of Clostridia spores (D130%C = 0.62) by exposing the surface to a treatment of 130%C for

3.7 min. (3 min. and 43 s.) at 3.5 bar. After treatment, the samples were placed carefully in an ice bucket for approx. 3 min. before checking for leakage and were put back in the ice bucket until sufficiently cooled. Sous vide treatment These sous vide treatments were performed in a 40 kg sous vide (SV) vessel (Classic Gastro A/S, Langeskov) corresponding to a D70%C = 0.52 minutes and z = 7 min. with the aim of providing a 6-log'” reduction of a 95% predictive interval of L. monocytogenes.

After heat treatment, the samples were cooled to 5% in the SV vessel. Samples from batches 1-3 and 5 were stored at 0-1 %C after sous vide-treatment and moved to 5°C and 8%C storage containers on day 0, along with the samples from batch 4 and 6.

Temperature was monitored by TESTO loggers (Testo, West Chester) located in the two cold rooms, and stored at 5°C and 8°C.

Trial designs of the Pathogen challenge test and Shelf life study 1 are shown in Tables 3-4.

Table 3 Pathogen challenge test , Variable = Pathogenchallengetest = Fr

EEE Inoculation Co botulinum em | Packaging... Vacuum packaging in boilable pouch | Thermal shock i 1. None : Lez EA shock (130°C for 3,7 min). | Sous vide cooking | Batch 1-4. 6 log reduction on L. : i mønocytogenes (D70=0,52 min, z = 7): RE = BA min | Replicates IX 3 mmm Table 4 Shelf life study 1 18 Variable — Shelflife study 4 | Packaging | Vacuum packaging in boilable pouch +... | Thermal shock inone meme | Sous vide cooking Batch 5-6. 6 log reduction on i. : | monocytogenes {D7=0,52 min, z = 7) at | meeen 00°C holding time = B4 min | Storage | 5% and 8°C for up to 120 days for TS treated | mmm | SEM PTES and 57 days for un-treated samples. | Replicates KS mmm Sensory analysis For this analysis, samples were taken from each of the storage containers (5%C and B%C) and put in the laboratory for a minimum of 30 minutes equalization before analysis. Gas production was initially evaluated. Vacuum packages were placed in a plastic bag and cut open, and outer bag was closed with a clip. Samples rested for 5 min. before further evaluation. Seven experienced {untrained} odour assessors whore masks as a safety precaution when evaluating odor and appearance on a 4 point structured scale from 1-4 {1 = not deviating from fresh, 2 = slightly deviating, but acceptable, 3 = considerable deviating, not acceptable, 4 = distinctly deviating, not acceptable). Samples were subsequently sent to microbiological testing,

DK 2020 01012 A1 14 Microbiological analysis Aerobic total viable count (TVC) and anaerobe Clostridia were only determined on samples from the pathogen challenge test. Only aerobic TVC was determined in the shelf life study. Collected results were multiplied by the dilution (0.357) in order to go from cfu/ml to cfu/g. Aerobic total viable count Samples were transferred to stomacher bags, and no liquid was applied. 250 ml PCP (physiological cooking salt, 0.9%, with peptone) was added to each stomacher bag before being massaged. Samples were assumed to be 10-1 diluted. Aerobic TVC was determined after 5 days at 20°C, using plate count agar (PCA) (Oxoid CM 0325). Clostridia spores and vegetative cells For spore determination, dilutions were collected in 5 ml tube and placed in a water bath (75%C for 20 min.) in order to remove the background flora, before spread on SFP agar (Shahidi Ferguson Perfringens agar) with 5% egg yolk (no antibiotics) and RCM agar (Reinforced Clostridia Medium agar) for comparison. They were anaerobically incubated for either three days at 30°C or four days at 25°C, depending on the weekday. For vegetative cell determination dilutions were spread directly and only on the SFP-agar before incubated. Subsequent shelf life study The study was divided into 4 batches, batch 1-2 treating pork necks and batch 3-4 treating pork loin samples. The batches were treated over a period of 4 days.

43 pieces of both pork necks and loins with pH 5.8-6.0 and 5.4-5.6, respectively, were collected the same day at a Danish abattoir and stored at 0°C until sample preparation. All pieces were trimmed and cut before divided into three samples, marked as 1, 2, and 3. Neck samples had a thickness of 8 cm and while loin sample 1 and 2 were 14 cm and sample 3 was 16 cm thick. A total of 129 samples were made from neck and loin, respectively, each weighing 600 g + 20 g.

Thermal shock treatment and sous vide-treatment were performed as described above.

Table 5 Trial design | Product i 1. Pork neck : mm Ef POE IOI | Packaging | Vacuum packaging in bollablepouch +... | Thermal shock | 1. None ; Fee Æt Thermal shock (130%€ for 3,7. min) mms | Sous vide cooking | 6 log reduction on L. monocytogenes (D70=09,52 ; | min, z = 7) : \ | 1. Pork neck: at 60°C with a holding time of 84 min | er, OTK loin: af 58°C with a holding time of 161 min | Storage | 5% for up to 90 days for TS treated samples and 48 | Fm | 59 YS fOr UN-Ereated samples, ld | Replicates XXS mmm Example 3 45 Time to a &-log reduction In challenge tests on vacuum packed meat samples surface inoculated with spoilage bacteria, the fash-autoclaving has proven to more than double the time to which the mest was rendered unacceptable by consumer panellists judging both odour and appearance compared with normal hot water treatment. The method can thus double conventional shelf-life of vacuum backed meat products without using chemical inhibitors such as by adding salt, sodium nitrite, sodium lactate, sodium acetate or by lowering pH.

On two different processed meat products the invention's flash-autodaving provided shelf-life extensions from 57 to 126 days and 80 to 150 days respectively without measurable degradation of odour, texture or appearance as compared with normal hot water treatment.

Correspondingly, on vacuum packed fresh meat samples, the invented surface autoclavation increased shelf-life from roughly 50 days {conventional hot water treated samples} to roughly 110 days.

From the literature it is known that the average time Dret required to reduce the number of Clostridium botulinum spores by 90% (i.e. a 1 log unit reduction) at 120°C is

0.034 min. The corresponding z-value {the temperature-change necessary for changing the D-value time by a factor 10) is also provided as 18.6°C {van Asselt et al, 2006), From these figures the D values at neighbouring temperatures can be calculated from the following equation: . , . F—-IZ8

DK 2020 01012 A1 16 In order to achieve a 2 sigma (95%) reduction the prediction interval, corresponding to eliminating 95% of all Clostridium botulinum spores on the product surface, a D value of 0.85 min at 120°C must be applied to the above equation.

Treatment times to achieve a 6-log reduction of the non-proteolytic C. botulinum spores based on these data by Asselte et al. 2006, are presented in Table 6, below.

Table 6 Time to a 6-log reduction of C. botulinum spores botulinum value Asselt et min al, 2006 (4 sec) (12 sec.) | (42 sec) (144 sec) interval In Table 6, the D-value is the time required to reduce the spore count by 90% (i.e. a 1-log reduction). The z-value is the temperature change necessary for changing the D- value time by a factor 10.

The invented surface flash heat treatment (e.g. 130°C for 6-12 seconds) applied after vacuum packaging facilitates a doubling of the products shelf-life compared to no additional heat treatment for both processed and fresh meats products and at the same time gives an astonishing reduction of surface pathogen bacteria and spores. Applying the invented method to fresh meat does not alter the product texture or colour apart from a very thin layer (1-3mm) at the surface of the item (se figures 6) which will be unnoticed after additional treatment e.g. as sous vide. For already cooked products the flash heat treatment after vacuum packing does not leave visible traces.

The invented flash heat treatment involves an apparatus for rapidly loading vacuum packed meat to a pressurized chamber (4-5 bar), covering the products in the chamber with water at e.g. 130°C, maintaining the products submerged in the water for 6 - 30 seconds recycling the water to a pressurized hot water reservoir and emptying products from the treatment chamber. When necessary products can be rapidly cooled down by applying spray with cold water after the product.

DK 2020 01012 A1 17 List of reference signs This is a listing of various elements relating to the present invention and shown in the appended figures. Alternative/synonymous designations are separated by slashes.

1. System of the invention

2. Heat treatment chamber 2A. Gate/door for introduction and removal of meat products 2B. Aqueous space of the treatment chamber 2C. Air space of the treatment chamber 2D. Water level of the treatment chamber 2E. Treatment chamber pressure gauge/manometer 2F. Grate for supporting the meat product 2G. Treatment chamber water level indicator

3. External hot water reservoir/hydrophore 3A. Aqueous space of the water reservoir 3B. Air phase of the water reservoir 3C. Water reservoir water level of reservoir

4. Inter-connection channel/flow-valve 4A. Pressurised hot water supply to treatment chamber 4B. Pressurised hot water reflux to reservoir (3), or to drain (9)

5. Air pressure supply device/back pressure channel (pressure-on/pressure off channel) 5A. Treatment chamber pressure-off valve/excess-pressure valve

6. Water supply channel 6A. Reservoir pressure-off valve/excess-pressure valve 6B. Reservoir safety valve/excess-pressure valve 6C. Reservoir pressure gauge/manometer

7. Energy supply/heating device

8. Vacuum-packed meat products

9. Drain for draining excess water from the heat treatment chamber (2) 9A. Turbidity meter/turbidometer/nephelometer

10. Heat exchanger

11. Heating/cooling device for rapid heating/cooling of the meat products

12. Processing operator

Claims (10)

DK 2020 01012 A1 1 CLAIMS

1. A system (1) for conducting a thermal shock-treatment of one or more vacuum-packed meat products (8), which system is characterised by comprising the following elements: a. a heat treatment chamber (2), which heat treatment chamber is dimensioned to enclose the vacuum-packed meat products (8) in question, and capable of closing tightly and withstanding a large internal overpressure, and which heat treatment chamber (2) comprises: al. a gate/door (2A) for the supply and withdrawal of one or more vacuum- packed meat products (8); a2. an air pressure supply device/back pressure channel (5), for delivering an overpressure sufficient to withstand the corresponding pressure in the external hot water reservoir (3), which air pressure is adjustable and allows for regulating the water flow between the external water reservoir/hydrophore (3) and the heat treatment chamber (2); a3. and which heat treatment chamber (2) is connected to an inter-connection channel (4), for implementing a water flow between the external water reservoir/hydrophore (3) and the heat treatment chamber (2); and b. an external hot water reservoir/hydrophore (3), for storing and supplying pressurized hot water, which external hot water reservoir/hydrophore (3) comprises: bl. a water supply channel (6), which allows for water supply to the external hot water reservoir/hydrophore (3); b2. an energy supply/heating device (7), which can provide sufficient energy to maintain the intended pressure/temperature level; b3. and which external hot water reservoir/hydrophore (3) is connected to an inter-connection channel (4), for implementing a water flow between the external water reservoir/hydrophore (3) and the heat treatment chamber (2).

2. The system of claim 1, wherein the heat treatment chamber (2) comprises an air pressure supply/back pressure channel/pressure on valve (5), and a treatment chamber pressure-off valve/excess-pressure valve (5A).

3. The system of claim 1, wherein the inter-connection (4) consists of two channels, i.e. an input/supply channel (4A) and an output/diversion channel (4B).

DK 2020 01012 A1 2

4. The system of claim 1, wherein the external hot water reservoir/hydrophore (3) comprises a pressure-off valve/excess-pressure valve (6A).

5. The system of claim 1, wherein the heat treatment chamber (2) and/or the external hot water reservoir/hydrophore (3) comprise a water level meter.

6. The system of claim 1, wherein the heat treatment chamber (2) further comprises a drain (9) for draining excess water from the heat treatment chamber (2).

7. The system of claim 6, which system further comprises a turbidity meter (nephelometer) (9A) for checking for turbid water, for control of leaks from the vacuum- packed meat products (8).

8. The system of claim 1, wherein the heat treatment chamber (2) further comprises a heating device and/or a cooling device (11).

9. A method for rapid decontamination of the surface of a vacuum-packed meat product (8) by performing a thermal shock treatment of the meat product, which method comprises the subsequent steps of: a. vacuum-packing the meat product (8) in a heat resistant, food-grade material; b. placing the vacuum-packed meat product (8) in a heat treatment chamber (2), dimensioned to enclose the vacuum-packed meat products (8) in question, and capable of withstanding a large internal over-pressure; c. initiating the build-up of a back pressure in the heat treatment chamber (2) corresponding to the pressure in the external hot water reservoir/hydrophore (3), by opening the channel for pressure supply/back pressure channel/pressure-on channel (5); d. initiating the supply of pressurised, hot water from the external water reservoir/hydrophore (3) to the heat treatment chamber (2) by opening the inter- connection channel/flow-valve (4), and regulation of the transport/filling time by adjusting the back pressure through the channel for pressure supply/back pressure channel (5); e. initiating thermal shock treatment of the vacuum-packed meat product (8), by maintaining the desired pressure/temperature for the desired treatment-period: f. discharging the pressurised, hot water from the heat treatment chamber (2) back to the external water reservoir/hydrophore (3), or by discharge to a drain (9), by increasing the back pressure through the channel for pressure supply/back pressure channel (5);

DK 2020 01012 A1 3 g. when emptied, maintaining the pressure in the heat treatment chamber (2) until the meat product (8) has cooled sufficiently in order to prevent boiling of water inside the vacuum pack; and h. decreasing the pressure within the heat treatment chamber (2) by opening the channel for pressure supply/back pressure channel (5) and release of the over- pressure, and removal of the heat-treated meat product (8).

10. The method of claim 9, which method is carried out as an additional process in connection with the repackaging of meat products, and optionally in a combination with other heat treatment processes.