ABSTRACT
Retortable pouch packaging is receiving renewed interest in thermal processing of foods. The retort pouch is replacing the conventional metallic can to a great extent because of the ability of the pouch to withstand thermal processing and the convenience associated in handling the product. Food-canning companies are increasingly using pouches to replace the metallic can, glass jar, or aluminum foil, with a view to appeal modern generations of customers. The pouch, which is lighter in weight than the can offers better convenience in food handling. Unlike the metallic cans, the boil-in-bag facility offers warming the food in the pouch immediately before consumption.1 The concept of the retort pouch dates back to the 1940s, when shelf-stable packaging was examined for military rations, although it lost its appeal until recent events, which include changes in consumer lifestyles, progress in packaging technology and shortage in metal cans brought it back to a position of prominence.2 In the present times, retort pouches and trays are gradually penetrating the food markets as an option for convenient shelf-stable products.2-5 The advent of the retort pouch-processing technology has also made availability of shelf-stable ready-to-eat (RTE) foods a reality. A variety of RTE foods are being manufactured by several multinational companies world over. In India, for example, production of RTE foods has reached an annual value of about US$20 million.3 These products, as home meal replacement options, have high acceptability among middle-class consumers in the country. Some of these products, include vegetable curries, pudding in tubes, as well as coffee and dairy beverages in plastic bottles.3 Developments in retort pouch technology have also helped advances in aseptic packaging.2,3
Retort pouches are extensions of conventional pouches making them capable of withstanding thermal inputs required to achieve sterility and consequent ambient temperature shelf stability. Basically, a retort pouch is a flexible, laminated pouch (or tray, dish, bowl, or cup). The packaging material is a laminate of three materials, an outer layer of polyester, a middle aluminum foil, and an inner layer of polypropylene. The outer polyester layer gives the pouch strength, abrasion resistance, and a surface for printing information about the contents. The aluminum layer functions as a moisture, light, and gas barrier, while the inner layer is the heat-seal and food-contact material. For a prolonged shelf life of processed
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must provide superior barrier properties, seal integrity, toughness, and puncture resistance and must also withstand the rigors of thermal processing. The thinner retort pack allows shorter thermal processes to retain flavors in the final product.
