CAC_RCP 60-2005 CODE OF PRACTICE FOR THE PREVENTION AND REDUCTION OF INORGANIC TIN CONTAMINATION IN CANNED FOODS
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ID： |
0C60EF56FB7743BB82B9BBC846FC04CD |
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文件大小(MB)： |
0.05 |
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页数： |
10 |
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文件格式： |
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日期： |
2006-7-3 |
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购买： |
文本摘录（文本识别可能有误，但文件阅览显示及打印正常，pdf文件可进行文字搜索定位）：
CAC/RCP 60-2005 Page 1 of 10,CODE OF PRACTICE FOR THE PREVENTION AND REDUCTION OF INORGANIC TIN,CONTAMINATION IN CANNED FOODS,CAC/RCP 60-2005,INTRODUCTION,HISTORY OF USE OF TIN,1. Tin is a soft, white, lustrous metal with an atomic weight of 118.7 and the chemical symbol Sn,after its Latin name, Stannum. It has a relatively low melting point (231.9oC) and is highly resistant to,corrosion, which makes it an ideal element for the protective coating of metals. Over 50% of the,world’s tin production is used for plating steel or other metals.,2. Today some 15 million tonnes of tinplate are produced each year using rapid and highly,sophisticated production methods. These methods are able to control steel thicknesses and tin coating,masses to within the extremely fine tolerances required for modern can making processes such as high,speed welding.,TIN AS PACKAGING FOR CANNED FOOD,3. Tin is used to protect the steel base from corrosion both externally (aerobic conditions) and,internally when in contact with foods (anaerobic). Under the anaerobic conditions expected inside an,internally plain processed food can, tin will normally behave as the sacrificial anode, dissolving very,slowly whilst protecting the steel base from corrosion and creating a reducing environment in the can.,It is this mechanism that has enabled the plain tinplate can to maintain its long history and proven,track record of providing wholesome food on a year round basis and safe storage for long periods of,time.,4. The later development of can linings (lacquers) enabled different types of food products to be,satisfactorily packed. For example, some highly pigmented foods (beetroot, berry fruits) have their,colours bleached by tin dissolution and are best protected from contact with tin by use of linings. A,small number of food products (e.g. sauerkraut) have a different corrosion mechanism, in which the tin,does not behave sacrificially and direct corrosion of the steel base can occur. These products should,also have the additional protection of an internal lacquer system.,5. The uses of tin have changed considerably over the years. Humans have, however, been,exposed to tin for centuries, through the food they eat, with no known negative long term effects.,Only limited data is available on the toxicological effects of inorganic tin as present in canned foods,resultant from dissolution of the tin coating. The main potential hazard from acute ingestion seems to,be gastric irritation in some individuals from exposure to high levels.,6. Hence the canning industry worldwide and government regulators consider it both desirable and,in accordance with good manufacturing practice that measures be adopted to minimise the levels of tin,in canned foods, whilst continuing to allow for the functional use of plain tinplate cans.,TECHNOLOGICAL AND COMMERCIAL IMPLICATIONS,7. Metal packaging faces strong competition from glass and plastics. Even with innovations such,as easy opening tear top cans, metal containers are below the average growth of market share for,packaging products.,8. The best solution to prevent or reduce detinning of cans by aggressive foods is internal,lacquering. The use of lacquers has permitted the extension of the use of cans to additional products,including highly aggressive ones.,9. The coating thickness greatly affects the performance of the lacquered food can. Nonaggressive,products such as apricots and beans require a thickness of 4-6μm while tomato concentrate,needs layers of 8-12μm to prevent interaction between the can and its contents.,CAC/RCP 60-2005 Page 2 of 10,10. Adhesion is required to prevent reactions between the can and its contents. Currently adhesion,is tested by measuring the force required to lift a dry lacquer coating from the metal in a peel test.,While this test readily identifies films which are unsuitable there is no guarantee that those which pass,would give satisfactory long term results when in contact with specific foods.,11. Toxicologically significant contamination of canned food from tin dissolution may arise as a,result of poor manufacturing practices or prolonged/incorrect storage or both.,12. Although lacquering of cans significantly reduces the risk of tinplate corrosion, the use of,lacquer coatings is not always practicable or cost effective.,13. It could be argued that “since lined cans are readily available, then why not use them for all,canned foods and thus prevent any tin uptake?” There are, however, very valid technical and,marketing reasons why some products require to be packed into plain cans.,FLAVOUR AND COLOUR,14. The need for tin dissolution to maintain the ……
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