Introduction Our tray sealing machines (table top series, rotary and conveyor type) support gas flushing process to produce a Modified atmosphere packaging (MAP) in a rapid period of time without the need to use of vacuum pump (with the exemption of VG machines).  Modified atmosphere packaging (MAP) is an increasingly popular food preservation technique whereby the composition of the atmosphere surrounding the food is different from the normal composition of air. The modification process often tries to lower the amount of oxygen (O2), moving it from 20% to 0%, in order to slow down the growth of aerobic life forms and the speed of oxidation reactions. The removed oxygen can be replaced with nitrogen (N2), commonly acknowledged as an inert gas, or carbon dioxide (CO2), which can lower the pH or inhibit the growth of bacteria.   What is MAP? MAP is food packaging in which the earth’s normal breathable atmosphere has been modified in some way. Usually combined with lowered temperatures, it is a highly effective method for extending the shelf-life of food. Shelf-life is prolonged in some applications by creating a simple vacuum in the package (vacuum packaging) and in these cases there is almost a complete absence of gas. In others, special permeable films allow naturally respiring produce to form its own atmosphere without the addition of external gases. Once a fruit, vegetable or animal product is harvested or slaughtered it remains a suitable environment for bacteria which continue to function using the available carbohydrate, protein, fat and nutrients. These continuing processes lead to degradation including undesirable colour changes, loss of flavour and poor texture. The action of enzymes also causes deterioration of foods. In Europe, MAP mainly involves the use of three gases - carbon dioxide, nitrogen and oxygen, although other gases are used where regionally acceptable. Products are packed in a single gas or a combination of these three gases depending on the physical and chemical properties of the food. History of MAP The use of gases in the preservation of food products is by no means a new process. Much of the original work was carried out in the early 1930s with the shipment of beef and lamb carcasses from Australia and New Zealand to the UK under carbon dioxide storage. During the 1940s and 1950s, sealed controlled atmosphere storage warehouses were constructed to prolong the effective shelf-life of fresh apples under refrigeration. Hence the commercial applications of gas preservation were largely confined to the controlled atmosphere storage and transport of bulk commodities such as meat and fruit. Now you see MAP used to package anything from fresh salads and individual meat portions, to sandwiches and snacks. Today it is a sophisticated technique with ever-increasing benefits to both supplier and customer. MAP – adding value to food Food, glorious food - in all its natural, eye-catching colour - is what the customer expects from the food industry. And week in, week out, Modified Atmosphere Packaging techniques help the retailer to deliver. Extended shelf-life, greater choice and a reduction in food-related health hazards are some of the valuable benefits of MAP but are not so apparent to the shopper as the presentation of the food itself. This is where MAP adds even more value for the retailer enabling food to look better for longer.   Why use MAP? In the last 25 years, the change from an industrialised base to a service economy has seen the emergence of new family structures and work patterns which, in turn, has led the demand for more convenient food. The creation of nationwide, European and international supermarket chains, has led to a highly competitive trading environment, forcing quality up and operational costs down For the food industry, one of the important effects of these significant social, economic and business changes has been to open the door to MAP. Hundreds of food businesses have stepped through, using MAP to form valuable new trading relationships with the multiples and other, smaller chains and independents. Because Modified Atmosphere techniques are ever changing and improving, that door of opportunity remains open. There is a great deal of advice and support available from equipment and film manufacturers, specialist gas suppliers such as BOC and Air Liquide in Australia and research bodies such as Food Science Australia.   Extension of shelf-life Depending on product, shelf-life can be usefully extended by between 50% and 500% using MAP techniques. This means that waste is minimised and re-stocking and ordering can become more flexible. As an example, a store turning over 100% of its shoppers every 10 days will be able to offer a non-MAP food item with a shelf-life of three days to just 30% of its customers. But the same food item packaged with a suitable Modified Atmosphere to give it a 10-day shelf-life will be available for purchase by ALL the store’s shoppers. Minimisation of waste If there is a greater chance that a product will be sold, there is obviously less chance of it being thrown away. Even with today’s sophisticated management systems it is still not possible to accurately predict a supermarket's daily throughput. So having a greater shelf-life available enables a store to order more efficiently and to reduce wastage. Quality There are obvious quality advantages for both retailer and consumer in having food that deteriorates at a much slower rate on its journey from production area to store, and then onward to the domestic kitchen, refrigerator or freezer. Presentation is another vital quality aspect. Because MAP products cannot just be wrapped in cling film (they have to be encased, usually in a tray which lends itself to an element of design on its surface) retailers have taken the opportunity to package their food stuffs more attractively. The visual appeal of food is another key quality area and here the industry’s experience with red meat makes an interesting case study. After slaughter and ageing, red meat quickly becomes a dullish, brown colour which is unattractive to customers. Fresh, red colour is maintained longer using a mixture of between 70% and 80% oxygen, (depending on the meat), and carbon dioxide for the balance. Its remarkable effect on red meat is undeniable. In the early days it was the introduction of this technique by Marks & Spencer to its range of red meats that kick-started the use of MAP in the UK. Today, with red meat coming under scrutiny by some consumers actively pursuing a healthier lifestyle, the role of MAP is central to its survival on store butchery shelves. Reduced need for artificial preservatives In a world which is becoming increasingly “green” in its outlook, a world where every consumer is a watchdog for the environment, there are points to be earned by the retailer who can get rid of as many additives as possible and show that its food is basically fresh and natural. In some cases, MAP means that artificial preservatives are no longer required to achieve a reasonable shelf-life. Increased distribution possibilities Because of the extended product shelf-life, increased distribution is one of those areas in which the introduction of MAP is more than just “another benefit”. For companies with the right product, the potential to increase the range of delivery can produce exciting changes and opens the door to a global market.   MAP gases – the basics Carbon dioxide (CO2) Carbon dioxide inhibits the growth of most aerobic bacteria and moulds. Generally speaking, the higher the level of CO2, the longer the achievable shelf-life. However, CO2 is readily absorbed by fats and water - therefore, most foods will absorb CO2. Excess levels of CO2 in MAP can cause flavour tainting, drip loss and pack collapse. It is important, therefore, that a balance is struck between the commercially desirable shelf-life of a product and the degree to which any negative effects can be tolerated. When CO2 is required to control bacterial and mould growth, a minimum of 20% is recommended. Nitrogen (N2) Nitrogen is an inert gas and is used to exclude air and, in particular, oxygen. It is also used as a balance gas (filler gas) to make up the difference in a gas mixture, to prevent the collapse of packs containing high-moisture and fat-containing foods, caused by the tendency of these foods to absorb carbon dioxide from the atmosphere. For modified atmosphere packaging of dried snack products 100% nitrogen is used to prevent oxidative rancidity. Oxygen (O2) Oxygen causes oxidative deterioration of foods and is required for the growth of aerobic micro-organisms. Generally, oxygen should be excluded but there are often good reasons for it to be present in controlled quantities including: Maintain fresh, natural colour (in red meats for example) To maintain respiration (in fruit and vegetables) To inhibit the growth of anaerobic organisms (in some types of fish and in vegetables)   Tray lidding to achieve MAP A traysealer uses ready-made trays that are sealed in much the same way as a thermoformer. The top web of packaging material (lid film) covers the filled pockets/trays. The air is evacuated from the sealing die and protective gas is added. Then the pack is sealed by the application of heat and pressure. Tray lidding machines are available from tabletop (manual) for the small producer, to fully automatic inline versions for larger processors.   HACCP - The hazard analysis and critical control point concept Hazard analysis and critical control point (HACCP) was developed in the 1960’s primarily by the Pillsbury Company to assure the safety of food manufactured for astronauts. It uses a proactive preventative approach to all stages of food manufacture including storage, distribution and retail. This is potentially much more effective than traditional end product testing in assuring safe food. Internationally it has become the pre-eminent food safety management system. It has become a legal requirement in many countries, particularly for fish and meat products. Systems based on the principles of HACCP have been incorporated into the EC food Hygiene directives. New regulations from the EU come into force on 1st January 2006; these will make systems based on HACCP a legal requirement for all food businesses except those in primary production. HACCP is a basic requirement of food standards, such as the BRC Global Standard-Food. Prior to developing a HACCP system a food business must have in place effective prerequisite programmes, based upon Good Manufacturing Practice (GMP) and Good Hygiene Practice (GHP). These will provide a firm foundation for the HACCP and will manage the low risk food safety hazards as well as legal, quality and commercial issues. These will be of site-wide relevance and not specific to a particular step of the process, specific food safety hazards will be managed through the HACCP system. Typical prerequisites would include cleaning procedures, personal hygiene rules, pest control and maintenance procedures. Effective prerequisite programmes enable the HACCP system to focus on significant food safety hazards, particularly at the critical points of the process. Guidance on HACCP produced by the Codex Alimentarius Commission in their Food Hygiene Basics Texts is widely used. Codex defines 7 principles that should be followed by food businesses developing and maintaining HACCP systems. HACCP Principles PRINCIPLE 1 Conduct a hazard analysis. Prepare a flow diagram of the steps in the process. Identify and list the hazards with their causes and specify the control measures. PRINCIPLE 2 Determine the critical control points (CCPs). A decision tree can be used. PRINCIPLE 3 Establish critical limit(s) which must be met to ensure that each CCP is under control. PRINCIPLE 4 Establish a system to monitor control of the CCP by scheduled testing or observations. PRINCIPLE 5 Establish the corrective action to be taken when monitoring indicates that a particular CCP is not under control or is moving out of control. PRINCIPLE 6 Establish procedures for verification to confirm that the HACCP is working effectively, which may include appropriate supplementary tests, together with a review. PRINCIPLE 7 Establish documentation concerning all procedures and records appropriate to these principles and their application. N.B. The wording given in italics is not included in the principles of HACCP as documented by the Codex Alimentarius Commission but is included here as additional explanatory notes. Key Stages of application Codex also provides guidance on how to apply these principles following a number of key stages. It has been suggested that there are 14 key stages STAGE 1 Define terms of reference/scope of the study STAGE 2 Select the HACCP team STAGE 3 Describe the product STAGE 4 Identify intended use STAGE 5 Construct a flow diagram STAGE 6 On-site confirmation of flow diagram STAGE 7 List all potential hazards associated with each process step, conduct a hazard analysis and consider any measures to control STAGE 8 Determine CCPs STAGE 9 Establish critical limits for each CCP STAGE 10 Establish a monitoring system for each CCP STAGE 11 Establish a corrective action plan STAGE 12 Verification including validation STAGE 13 Review the HACCP system STAGE 14 Establish documentation and record keeping A food manufacturer will need to identify and analyse potential and realistic hazards at all stages of their operation, typically from intake of raw materials to at least despatch. Where relevant biological, chemical and physical hazards should be considered. The business will need to determine the measures it uses to control the significant food safety hazards. Critical Control Points (CCPs) will be determined using professional judgement and experience. Critical limits must be set for the controls at the CCPs, these must be monitored at an appropriate frequency. A corrective action plan must be developed to enable effective management of situations where critical limits are not achieved. Procedures must be in place to ensure the HACCP systems are working effectively and this must include review. The business must prepare and use appropriate procedures and records.   Summary of the achievable shelf life with and without MAP as advices by BOC (on storage temperature of  0oC to +3oC)   Food Products without MAP With MAP Ready Meals, Pasta Dishes, Goulash, Casseroles, Sauces, Soups containing meat, fish and poultry... 2-5 days 5-21 days Filled Pasta, breaded poultry, meat or fish, pizzas, meat pies, stuffed pitta bread, quiche, sausages, rolls, bouchee, chinese rolls... 4-7 days 7-21 days Summary of the achievable shelf life with and without MAP as advices by Air Products (on storage temperature of  0oC to +3oC) Food Products without MAP With MAP Ready Meals and Other Cook-Chill Products 2-5 days 5-10 days Fresh Whole and Prepared Fruit and Vegetable Products 2-7 days 5-35 days Dairy Products 1-4 weeks 2-12 weeks Cooked, Cured and Processed Meat Products Cooked and cured meats in 1-3 weeks, salami etc. 3-6 month Cooked and cured meats in 3-7 weeks, salami etc. 4-8 month Raw, low fat white Fish and Seafood / Crustaceans and Molluscs 2-3 days 4-6 days Cooked and Dressed Vegetable Products 3-14 days 7-21 days Useful Links Food Science Australia (CSIRO) - Active Packaging http://www.foodscience.afisc.csiro.au/actpac.htm