December 4, 2007 By Jung H. Han Ph.D
An excerpt from the new book “Innovations in Food Packaging.”
Year after year, (packaging) technology becomes better. Most developments in the food technology have been oriented to process food products more conveniently, more efficiently, less costly, better in quality and higher in safety. Traditional thermal processes have offered tremendous developments in the food processing industry. These include: commercial sterilization; quality preservation; shelf-life extension; and safety enhancement. Extended shelf stable products, manufactured by retorting or aseptic processing, are available in any grocery store and do not require refrigeration. These types of products are very convenient in any place or time and are easy to handle, benefiting producers, processors, distributors, retailers and consumers. The major function of extended shelf stable food packages is barrier protection against the invasion of micro-organisms.
Extra Active Functions of Packaging Systems
Many new ‘extra’ functions have been introduced in active packaging technologies. Such ‘extra’ functions include: oxygen scavenging function; antimicrobial activity; atmosphere control; intelligent functions; edibility; biodegradability, etc. Food packaging serves beyond its conventional protective barrier property. The new active packaging systems function to increase security, safety, protection, convenience, and information delivery. Active packaging systems extend the shelf-life of food products by maintaining their quality longer, increasing their safety by securing foods from pathogens and bioterrorism, as well as enhancing the convenience of food processing, distribution, retailing and consumption.
There are many applications for active packaging technologies, and several have been commercialized and are used in the food industry. These include: oxygen scavenging systems; carbon dioxide absorbing systems; moisture scavenging systems (desiccation); and antimicrobial systems.
Oxygen scavenging systems have been commercialized in the form of a sachet that removes oxygen. An oxygen-free environment can prevent food oxidation and rancidity as well as the growth of aerobic bacteria and moulds. Carbon dioxide scavenging packaging systems can prevent the package from inflation with carbon dioxide gas that has been formed after the packaging process. For example, packaged coffee beans may produce carbon dioxide during storage as a result of non-enzymatic browning reactions. Fermented products such as kimchi (lactic acid fermented vegetables), pickles, sauces, and some dairy products can produce carbon dioxide after the packaging process. Carbon dioxide scavenging systems are also quite useful for products that require a fermentation and aging process after they have been packed. Moisture scavenging systems have been used for a very long time for dried foods, moisture sensitive foods, pharmaceuticals and electronic devices. Desiccant materials have been included in the package in the form of a sachet. Recently, the sachets contain humectants as well as desiccants to control the humidity inside the package more specifically. Moisture scavenging systems that are based on desiccation are evolving to control the moisture by maintaining a specific relative humidity inside the package by absorbing or releasing the moisture. Antimicrobial packaging applications are directly related to food microbial safety and bioterrorism, as well as to shelf-life extension by preventing the growth of spoilage and/or pathogenic micro-organisms.
Modified Atmosphere Packaging (MAP)
MAP is traditionally used to preserve the freshness of produce, meats and fish by controlling their biochemical metabolism, such as respiration. Nitrogen flushing, vacuum packaging and carbon dioxide injection have been used commercially for many years. However, current research and development has introduced new modified atmosphere technologies such as inert gas (e.g., argon) flushing for fruits and vegetables, carbon monoxide injection for red meats and high oxygen flushing for red meats. For a MAP system to effectively work, optimum packaging material selection with proper gas permeability properties must be selected. The use of MAP systems has been attractive to the food industry since there is a fast growing market for minimally processed fruits and vegetables, non-frozen chilled meats, ready-to-eat meals and semi-processed bulk foods.
MAP dramatically extends the shelf-life of packaged food products. In some cases it does not require any further treatments or any special care during distribution. However, in most cases, extending shelf-life and maintaining quality requires a multiple hurdle technology system. For example, introducing a temperature control as well as MAP is generally essential to maintain the quality of packaged foods. Hurdle technology is therefore important for MAP applications, since the modified atmosphere provides an un-natural gas environment that can create serious microbial problems such as the growth of anaerobic bacteria and the production of microbial toxins. Therefore, an included temperature control system is very important for quality preservation and microbial control.
New Food Processing Technologies
Besides the traditional thermal treatments for food preservation, many other new thermal and non-thermal processing technologies have been recently developed. These include: irradiation; high pressure processes; pulsed electric fields; UV treatments; antimicrobial packaging, etc. Some of these processes have been commercially approved by regulatory agencies for food packaging purposes. These new technologies generally require new packaging materials and new design parameters so that optimum processing efficiency occurs. For example, packages that undergo an irradiation process are required to possess chemical resistance against high energy to prevent polymer degradation. UV treatments require UV light transmittable packaging materials. Retortable pouches should resist pressure changes and maintain seal strength.
Since these new technologies possess their own unique characteristics, packaging materials should be selected with these characteristics in mind.
Future Trends of Food Packaging
Continuing trends of food packaging technologies is to study new material development that possesses very high barrier properties. High barrier materials can reduce the total amount of packaging materials to be required, since they are excellent barriers made of a thin layer or are light weight. The use of high barrier packaging materials reduces the costs in material handling, distribution/transportation and waste reduction. The development of high barrier properties of packaging materials has progressed and will continue in the future. Convenience is also a hot trend in food packaging developments.
The convenience at the manufacturing, distribution, transportation, sales, marketing, consumption and waste disposal levels is very important and competitive. Convenience parameters may be related to the productivity, processibility, warehousing, traceability, display on shelf, tamper-resistance, easy opening and cooking preparation. Thirdly, an important trend is safety, which is related to public health and security such as bioterrorism, especially due to the increase in the consumption of ready-to-eat products, minimally processed foods and pre-cut fruits and vegetables. Food-borne illnesses and malicious alteration of foods must be eliminated from the food chain. Another significant issue in food packaging is natural and environmentally friendly systems. The substitution of artificial chemical ingredients in foods and in packaging materials with natural ingredients is always attractive to the consumers. Many ingredients have been substituted with natural components. For example, many chemical antioxidants such as BHA, BHT and TBHQ have been replaced with tocopherol and ascorbic acid mixtures for food products. This trend will also continue in food packaging system design areas. To design environmentally friendly packaging systems that are more natural requires, for example, the partial replacement of synthetic packaging materials with biodegradable or edible materials, consequently, the decrease in the use of total amount of materials, and the increase in the amount of recyclable and reusable (refillable) materials. Food science and packaging technologies are linked to engineering developments and consumer studies. Consumers tend to continuously want new materials with new functions. New food packaging systems are, therefore, related to the development of food processing technologies, life-style changes and political decision-making processes as well as scientific confirmations.
Reprinted from Chapter One of “Innovations in Food Packaging,” edited by Jung H. Han, June 2005, with permission from Elsevier.
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