TITLE
Method for producing an improved packaged cooked meat product
FIELD OF THE INVENTION
The present invention relates to a method for producing packaged meat products with improved characteristics relative to those currently available. More particularly, it relates to a method of producing a bacteria free packaged meat product with an extended shelf life. The invention also relates to the packaged meat products produced according to the method.
BACKGROUND ART
In the packaged food industry there is an over-riding requirement to provide products that are free from dangerous contaminants such as bacteria including those found commonly in chicken i.e. Listeria sp, Salmonella sp, Pseudomonas sp, coagulase positive Staphylococci sp, E. coli, Campylobacter sp, Shigella sp and Yersinia sp.
In the cooked chicken meat market, manufacturers depend on manufacturing practices established using tools to assess the critical parts of the production processes such as the Hazard Analysis and Critical Control Point ("HACCP") system. However, whilst use of tools such as HACCP and the like assist in avoiding the production of contaminated food products they do not provide any particular process that can be employed to ensure the production of safe packaged meat products.
At present, there is no suitable process available for the production of packaged meat products that guarantees freedom from bacteria such as Listeria sp, Salmonella sp, Pseudomonas sp, coagulase positive Staphylococci sp, E. coli, Campylobacter sp, Shigella sp and Yersinia sp. The present invention seeks to overcome this problem or at the very least offer an alternative to the currently available methods.
DISCLOSURE OF THE INVENTION
The present invention provides a method for producing an improved packaged cooked meat product comprising the steps of:
(i) placing the meat into a heat resistant packaging means to form a packaged meat product;
(ii) removing substantially all the air from within the packaged meat product and sealing it; and
(iii) heating the packaged meat product to render the meat bacteria free.
The packaged meat product produced according to the present invention is bacteria free. For the purposes of the present invention the term "bacteria free" is defined as a level of Listeria sp such as Listeria monocytogenes, Salmonella sp such as Salmonella salford, Pseudomonas sp such as Pseudomonas aeruginosa, coagulase positive Staphylococcus sp, Campylobacter sp such as Campylobacter jejuni, Shigella sp such as Shigella sonnei, Yersinia sp such as Yersinia enterocilitica and E. coli that renders the meat safe for human consumption and includes a level where one or more of the listed bacteria are entirely absent.
The present invention may be applied to various types of meat including beef, lamb and ham and other smallgoods. Preferably, the meat is chicken.
The meat may be substantially fat free and have a fat content of less than about 2%. Alternatively, the meat may have greater than 2% fat content.
When the meat has greater than about 2% fat, undesirable fat deposits may appear during the method deposits. The fat in the deposits is liberated from the meat during the processing steps of the method. To address this problem the method of the present invention may further comprise a pre-treatment step in
which the cooked meat is mixed with an agent that prevents the appearance of the fat deposit.
Thus, the present invention also provides a method for producing an improved packaged cooked meat product comprising the steps of:
(i) mixing the meat with an agent adapted to prevent the appearance of a fat deposit during the method;
(ii) placing the meat into a heat resistant packaging means to form a packaged meat product;
(iii) removing substantially all the air from within the packaged meat product and sealing it; and
(iv) heating the packaged meat product to render the meat bacteria free.
The agent may be varied and includes substances that absorb liberated fat. When the agent is a fat absorbing agent then it may be a protein rich additive such as a soy based additive. One particular soy based additive that may be used in the method of the present invention is a powdered soy isolate containing at least 70% protein and 5% water. It will be appreciated that the level of protein in the additive may be adjusted in accordance with the amount of fat in the meat. The higher the fat content, the higher the protein content required in the additive.
The product of the present invention is adapted for storage over extended periods of time. When it is desired to produce a product with maximum shelf life, the method of the present invention may further comprise the step of cooling the packaged meat product to at least limit the growth of other bacteria. It will be appreciated that the other bacteria are those that survive the heat treatment step of the method.
Thus, the present invention also provides a method for producing an improved packaged cooked meat product comprising the steps of:
(i) placing the meat into a heat resistant packaging means to form a packaged meat product;
(ii) removing substantially all the air from within the packaged meat product and sealing it;
heating the packaged meat product to render the meat bacteria free; and
(iv) cooling the packaged meat product to at least limit the growth of other bacteria.
The temperature of the cooling step may be varied and preferably is about 5°C or lower. The time taken to achieve the cooling may also be varied and preferably is 60 minutes or less. Thus, in one particularly preferred form of the invention the packaged meat product is cooled to 5°C in less than or equal to 60 minutes.
The cooling may be achieve by any means apparent to those skilled in the art and includes submersion in iced water and refrigeration.
The meat may be placed into the packaging means by any means readily apparent to those skilled in the art and includes by hand and automated means.
The heat resistant packaging means may be varied provided it is capable of withstanding the heat treatment step. The packaging means may be a transparent laminated bag with at least one of the characteristics set out in Table 2 and preferably all of the listed characteristics. However, it will be appreciated that based on the information herein, those skilled in the art will be able to routinely determine alternative bags for use in the method of the present invention.
The air may be removed from the packaged meat product by any convenient means and preferably is removed using a vacuum means such as a vacuum packing machine. For the purposed of the present invention "substantially all the air" is defined as the amount of air that must be removed to endure the later method steps are not compromised. Preferably, at least 95% of the air is removed and more preferably at least 99% of the air is removed.
The packaged meat product may be heated by conventional means apparent to those skilled in the art provided such means is compatible with the rest of the method steps. Preferably, the heating is achieved by submersing the meat product in heated water tank or by placing the meat product in a steam oven. In one particular form of the invention the meat product is heated in a specialised superheated retort specially adapted for food preparation.
The heating parameters may be varied. Preferably, the meat product is heated such that all the meat achieves at least 80°C and this temperature is maintained for at least 5 minutes. However, the heating temperature and the time it is maintained at the temperature may be varied as deemed appropriate by one skilled in the art depending on the particular meat product and the intended end use.
The method of the present invention allows for the convenient preparation of bacteria free packaged food product that is adapted for long shelf life and thus has considerable advantages over presently available food products that may contain dangerous bacteria and/or may develop dangerous levels of such bacteria whilst on the shelf.
The present invention also provides a packaged meat product produced according to any one of the methods described herein.
The present invention will now be described with reference to the following non- limiting examples.
EXAMPLES
Example 1: Preparation of a chicken meat product according to the present invention
A packaged chicken meat product according to the present invention was prepared as follows:
1. the chicken meat is cooked and prepared according to standard processes and then thoroughly mixed with 2% of powdered soy isolate A (see Table 1);
2. the mixture resulting from 1 is placed in a laminated barrier bag (see Table 2);
3. 99% of the air in the bag is removed using vacuum packaging equipment and double sealed;
4. the sealed bag from 3 are placed in either a submersible water tank or steam oven until all the chicken in the bag achieves 80°C for 5 minutes; and
5. the bag and its contents is submersed in iced water or refrigerated to bring the complete item to 5°C within 60 minutes of the completion of step (4).
Table 1
Table 2
Example 2 - Microbial testing of a chicken meat product
A cooked chicken meat product was spiked with bacteria and then treated according to the method set out in Example 1. The levels of particular bacteria before and after treatment were then assessed using standard microbiological techniques (Australian standards no 1766) and the results are detailed in Table 3 hereunder.
Table 3
Example 3 - Microbial testing of a chicken meat product
A cooked chicken meat product was spiked with additional bacterial species from those used in example 2 and then treated according to the method set out in Example 1. The levels of particular bacteria before and after treatment were then assessed using standard microbiological techniques (Australian standards no 1766) and the results are detailed in Table 4 hereunder.
Table 4
Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.