Essentials of Thermal Processing. Gary Tucker S.

Чтение книги онлайн.

СКАЧАТЬ packaging types are more recent and restricted to the past 40 years or so. Rigid plastics are useful for ready meals, as they are not breakable and can be heated in the microwave oven. Pouches are flexible and during processing the flat dimensions result in faster heat penetration, therefore shorter cooking times and better quality product. Pouches and some rigid containers come with their own challenges for thermal processing as their irregular shapes make it more difficult to measure the cold spot during processing. Tetra Recart's ‘square’ format saves space when packing and stacking. All of these options have their advantages and disadvantages. None of the plastics and laminates are as good a gas barrier as glass and metal. Light can also cause deterioration in some products, requiring tinted glass or opaque metal or cardboard casing.

      The ideal packaging choice depends on the requirements of product type, processing conditions, required shelf life, and target market.

1.4 DEVELOPMENTS IN CANNERY EQUIPMENT

      1.4.1 Seaming

      The equipment used in canneries also had to develop significantly. Originally, cans were manually soldered closed, and good artisans could do about 6 an hour. Once the hermetic double seam was invented, closing of cans became much faster. Today, there are seamers that can close over 1000 cans per minute.

      1.4.2 Processing

      Processing (heating) of the sealed cans started off as being an all‐day event. Appert processed most of his products in boiling water. He did experiment with pressure processing, but at that time ‘digesters’ were quite dangerous and it was not the norm. Around 1863, processors used ‘chemical baths’, where high concentrations of calcium chloride enabled ‘water’ to boil at temperatures approaching 121 °C. This allowed for significantly shorter cooking times. By 1870, basic steam retorts were being used to temperatures up to 121 °C, but they were still quite dangerous and hand operated.

      In 1950, the first reel and spiral continuous cooker was introduced and was something very innovative. It was the first retort that did not process in batches. It was called the Anderson‐Barngrover Cooker and was taken over by FMC and is currently John Bean Technology (JBT). These enabled cans to be processed much more efficiently at higher speeds, thus reducing production costs.

      Around the same time, aseptic filling was started. In 1961, flame sterilization (using direct gas flame heating of rolling cans) was introduced in France, as was the continuous hydrostatic pressure sterilizer. Today, with computers being able to control equipment we have many more options and more precise control. There are combinations of steam and air, raining hot water, and rotation. All of these developments have the objective to optimize temperature distribution and product heating to improve product quality. Modern retorts can process at temperatures up to 145 °C, yielding faster throughput.

1.5 FOOD SAFETY

The canning process was originally developed to preserve food safely and for long periods of time. Food safety is often taken for granted with thermally processed foods; however, this understates the efforts made by food companies to ensure their products are safe for consumers to eat. Safety of thermally processed foods is closely monitored using a system called Hazard Analysis and Critical Control Point, or HACCP (Bauman 1974). HACCP is a system that identifies areas of potential contamination within the food process and builds checkpoints, or CCPs, to ensure that the product safety is maintained at all times. Validation of a thermal process and the determination of appropriate CCP levels is a challenging exercise that requires in depth product knowledge and accurate temperature measurement tools.

      HACCP originated in the 1950s, when the National Aeronautics and Space Administration (NASA), the Pillsbury Company, and the U.S. Army Laboratories (Natick) collaborated to devise a food safety system to ensure that food for upcoming space expeditions was guaranteed to be safe. Critical Control Points (CCPs) were part of NASA's engineering management requirements (used to test weapon and engineering system reliability), and it was decided to use this concept for this food safety initiative to eliminate the potentially ‘critical failure areas’ in the food processing procedures. The programme was a success and the food produced proved to be safe.

      There were many food safety incidents over the years, but in 1971 two incidents are identified as being tipping points for the food processing industry to realize that they needed a more formal food safety programme: The first was when Pillsbury had a recall on a product called Farina, a cereal used in infant food in which glass pieces were found; and the second was a botulism incident from canned vichyssoise soup made by Bon Vivant. Pillsbury was fortunate to have had direct involvement in the HACCP programme developed for the production of the space mission food and so implemented a HACCP programme to convince their customers that a similar incident would not happen again. The National Canners Association and FDA learnt about the HACCP programme while deciding how to ensure better canned food safety as a result of the soup incident and so asked Pillsbury to give some of their inspectors HACCP training and by 1973 HACCP was used as part of the low acid food regulations that were published in the USA and soon used internationally (Dick and Launius 2007).

      Today, HACCP is used throughout the food industry and is generally considered to be part of Good Manufacturing Practice. It is published by the Food And Agriculture Organization (FAO) of the United Nations World Health Organization (WHO) as part of the Recommended International Code of Practice General Principles of Food Hygiene (Codex Alimentarius 1997).

HACCP is important because it prioritizes and controls potential hazards in food production. By controlling major food risks, such as microbiological, chemical, and physical contaminants, the industry can better assure consumers that its products are as safe as good science and technology allows (http://www.safefoodalliance.com).

References

      1 Appert, N. (1810). The Book for All Households or the Art of Preserving Animal and Vegetable Substances for Many Years. Glass Container Association of America. Translated by K.G. Bitting (1920).

      2 Bauman, H.E. (1974). The HACCP concept and microbiological hazard categories. Food Technology 28 (9): 30–32. 74.

      3 Bitting, A.W. (1937). Appertizing or The Art of Canning; its History and Development. San Francisco, CA: The Trade Pressroom.

      4 Codex Alimentarius (1997). Hazard Analysis and Critical Control Point (HACCP) System and Guidelines for its Application. Annex to CAC/RCP 1‐1969, Rev. 3.

      5 Dick, S.J. and Launius, R.D. (2007). Societal Impact of Spaceflight, NASA History Series. Washington, DC. Chapter 12.

      6 Ecklund, O.F. (1949). Apparatus for the measurement of the rate of heat penetration in canned foods. Food Technology 3 (7): 231–233.

      7 Featherstone, S. (2012). A review of developments in and challenges of thermal processing over the past 200 years – a tribute to Nicolas Appert. Food Research International 47 (2): 156–160.

      8 Goldblith, S.A. (1971a). Pasteur & truth in labelling “Pro bono publico” – in the best scientific tradition. Food Technology 25: 228–229.

      9 Goldblith, S.A. (1971b). A condensed history of the science and technology of thermal processing – part 1. Food Technology 25: 1256–1262.

      10 Goldblith, S.A. (1972). A condensed history of the science and technology of thermal processing – part 2. Food Technology 26: 64–69.

      11 Knock, G.G. (1952). Survey of soils for spores of Clostridium botulinum (union of South СКАЧАТЬ