Food Packaging Technology 3(2+1)

Lesson- 20 Disadvantages of packaging materials

20.1 Glass

Glass is one of the oldest manufactured materials and one of the first manufacturing businesses in the New World. Nonetheless, glass still serves as an important packaging material for food. The disadvantages of glass include its weight and vulnerability to fracture from thermal shock (rapid temperature change) and physical shock. In recent years, advances in the science and technology of glass have resulted in lighter, stronger glass containers. For those food products vulnerable to light-catalyzed reactions, glass’s transparency to light is another disadvantage. Use of light-absorbing colorants in the glass, as well as glass container labels and direct printing on the glass, will affect the transmission of light.

20.1.1 Disadvantages of glass

• glass is a heavy packaging material than others.

• breakage and subsequent loss of product

• hermetic seal that is more easily compromised

• the increased possibility of broken glass contaminating the finished product

• color changes of the product due to exposure of light

• expensive food packaging material

20.2   Metals

The disadvantages of metal containers include their multi-step manufacture, weight (particularly steel), and (for some foods) lack of transparency. In recent years,

 advances in the science and technology of these metals have resulted in lighter, stronger metal containers.

 20.2.1 Disadvantages of metal

• metal is corrosive material, can affect the quality of food

• metal is moderately heavy packaging material.

• Can’t see the food content after packaging

• Due to multi –step can manufacturing process, can making is time taking process

• Metal can react with the food material

 20.3   Plastic

Plastics are high molecular weight polymers that can be molded into desired shapes such as films, trays, bottles, and jars using heat and pressure. Plastics do not provide a total barrier to gases, water vapor, and aromas. The permeabilities of a given plastic material to water vapor, oxygen, carbon dioxide, and aromas depend on the particular polymer composition and structure. This must be considered when selecting a plastic for a specific application and desired shelf life. Plastics are often combined in layers, to take advantage of the unique barrier properties of each polymer. Similar to glass, plastic container transparency to light can be detrimental to foods vulnerable to light-catalyzed reactions. Pigmenting, labeling or direct printing of plastic containers can reduce this problem for sensitive food products. Plastic materials do not have the compressive strength of glass or metal, and only a few plastics have high enough heat resistance for heat processing or preparation of foods. Plastic additives and any residual monomers have potential for migrating into foods. Thus, much attention and testing are devoted to minimizing this possibility. On the other hand, food components such as aromas and flavors can sorb into plastic packaging, with resulting loss of food quality. Finally, most plastic materials used in food packaging are not recyclable. Fortunately, these are used in lower quantities than recyclable plastic containers.

20.3.1 Disadvantages of plastic

• Permeable to

• Gas

• Water vapor

• Aroma

• Monomers

• Additives

• Food components can sorb into plastic

• Low compressive strength

• Lack heat resistance (some)

• Not recyclable (some)

 20.4.   Retortable Pouches

The main disadvantage of retortable pouches, trays, tubs, and cartons is more difficult recycling. Pouch integrity and sealing have also been concerns that are addressed through vigorous package inspection and regulation. National Food Processors Association (NFPA) recommends several tests, including squeeze test, burst test, and seal tensile strength. Seals can also be tested using a dye penetration test or headspace gas composition test. Retorting of pouches and trays must include overpressure and critical control of pressure changes to prevent seal failure. Also, special racks or trays are incorporated in the retort to restrain pouches to a defined thickness for consistent heat transfer.

20.4.1. Disadvantage of retortable pouches

• to achieve equivalent cannery production efficiency, a major investment in new capital equipment for filling and processing is required
• production speed on single filler/sealer is usually less than half that of common can seamers
• new handling techniques have to be adopted and may be difficult to introduce
• heat processing is more critical and more complex
• to retain rapid heat penetration there are limitations on pouch dimensions
• some form of individual outer wrapping is usually required, adding to cost
• being non-rigid products such as some fruits lose their shape
• being a new concept, education of the consumer as to correct storage and use is required during marketing.