Читать книгу Essentials of Thermal Processing - Gary Tucker S., Gary S. Tucker - Страница 16

Other forms of packaging for ‘canned foods’ have also become popular and practical; including glass, various plastics, and composites. Although glass was not new – being the packaging that Appert used to develop his method, it was difficult to seal adequately and cans soon became the packaging of choice. Developments in the closures for glass, starting with the Mason Jar in 1858, resulted in glass becoming a popular alternate to cans. Improvements in glass making technology have resulted in bottles that don't break easily under the high heat and pressure conditions experienced during thermal processing. Improvements in lids, caps, and closures that form hermetic seals are easy to open and reclose and have tamper evident features such as buttons that ‘pop’ on first opening have helped to make glass a viable alternate.

Developments in other 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.