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Nowadays, food packaging demands that consumers be provided with packaging of high-quality standards which can be done by working towards enhancing the material performance and shelf life. The role of food packaging is to contain the food in an economical manner as much as possible and to be able to fulfill the desires of the consumers by ensuring that the food stays protected from any external damage or influence. Packaged foods may have a shelf life starting from a day and could go upto a period of 12 months. However, the selection of an apt packaging material would also require increasing dependence on several aspects that include physical, chemical, mechanical barrier, printability, cost-effectiveness and optical properties.

Glass

Glass

Glass is one of the oldest materials to be used to preserve food stuffs such as pickles. It is a popularly favoured packaging material, owing to its inert, reusable and recyclable properties. Glass is an excellent oxygen and moisture barrier when it comes in contact with food. Therefore, it can maintain the flavour and taste of food for a longer duration of time.

Glass containers can be reused by sterilizing them. As per each one’s requirement, it can be moulded into different sizes & shapes such as jars, bottles, containers, ampoules, etc. Due to the transparency of glass, consumers can easily see the food inside. Yet, there are some coloured bottles and containers as well for light-sensitive food products. The one demerit of glass packaging is its brittleness, which needs to be handled with care. Packaging of alcoholic beverages is an important application in the global market for glass containers.

Other than that, glass is used in milkshakes, juices, soft drinks and baby food packaging. There is about 8% linear growth observed in the production of glass containers once in five years.

Metal

MetalMetals are impermeable to light and have excellent mechanical strength, good thermal conductivity and resistance to relatively high temperatures. The last two properties make metal packages suitable for in-package thermal processing. Aluminum, tin, steel and chromium are extensively used metals for packaging.

Metal packaging includes cans, caps & lids for glass jars, bottles, wraps, foils, etc. Aluminum is used as an alloy which makes it more resistant to corrosion. This metal is abundantly used in making soft and hard drinks cans, as it is light in weight and comparatively cheaper than other metals. Aluminum foil is used to wrap chapatis, including some fast food items such as pav bhaji, papdi chaat, etc.

Tin and chromium are used as composite materials with steel. Tin-free steel, also called chromium oxide coated steel is coated with organic matter to make it resistant to corrosion completely. Large drums, oil cans, trays and bottle caps are made up of tin-free steel.

Plastic

Plastic JarNearly 70% of plastic production takes place by seven different types of plastic polymers. These are explained below and a serial number is also given to them which indicate their symbol on the food packaging or storing material:1. Polyethylene Terephthalate (PET) is produced by poly condensation of monomers, which is obtained either by esterification (terephthalic acid+ethylene glycol) or by trans-esterification (ethylene glycol+dimethyl terephthalate) reaction. It acts as a barrier to moisture, O2 and CO2. It is cost-effective, heat resistant, chemical resistant and shatterproof. Its weight is low and is colourless & odourless. In comparison to other plastics, PET is more inert. It is used to make bottles for water, juice, vegetable oil, alcoholic drinks and soft drinks.

2. High-Density Polyethylene (HDPE) is hard but light in weight with opaque texture. Butter and food storage containers, bottles for vinegar & chocolate syrup are made up of HDPE.

3. Polyvinyl Chloride (PVC) is made by adding more monomers in vinyl chloride. It possesses good heat sealability as well as excellent resistance to gases, moisture and oily substances. The application includes blister packaging used in strawberry boxes, chewing gums, mint and packaging tray, including its usage in meat, poultry, tea and coffee.

4. Low-Density Polyethylene (LDPE) is not too rigid, making it perfect for making flexible/squeezable bottles and flexible lids. It is chemical resistant and stable at variable temperatures. Hence, it is also used in the packaging of frozen foods, fruit & vegetable bags and bread.

5. Polypropylene (PP) is tough but weighs less. It is used in yogurt bottles, salad dressing bottles, cheese & margarine tubs, plastic bottle caps, etc. It is thermal resistant and hence it is also used in the production of microwave containers.

6. Polystyrene (PS) is a light weight and cost-effective material. Its properties include thermal insulation, moisture, air and water resistance. It is used in making disposable plastic bottles, plates, cups, bakery trays, egg cartons, etc.

7. Others – All plastics other than the six types mentioned above come under this category. These plastics may contain Bisphenol A.

Paper

Disposable cupsThe usage of paper, being the traditional mode of packaging material is commonly used at homes and it includes usage of newspaper, book paper, etc. It is 100% recyclable and eco-friendly. Various types of paper that are used in food packaging include:

Unbleached Kraft paper is formed by sulphate treatment process and looks light brown in terms of appearance. It is the strongest paper when compared to the rest of the papers. It is basically used as an outer packaging layer to prevent dust, moisture and shock. It is used in the packaging bags of sugar, flour, vegetables and dry fruits.

Bleached Kraft paper is also formed by the sulphate treatment process, but is bleached to make it whiter and bright. It is the strongest when we talk about white papers. It is generally used where appearance, printability and strength are important. It is used in envelopes, labels, flour and sugar packaging.

Sulphite paper is lighter and softer than kraft paper and the polished surface makes it water and oil-resistant. It can be coated for better printing and is also used for lamination with plastic or aluminum foil. Wrappers of biscuits and confectionery are made up of these laminated papers.

Greaseproof paper is produced by hydration of paper, due to which cellulose fibres break and make it more gelatinous to provide resistance to oil, fat and grease. This paper looks translucent in appearance. It is used to wrap snack foods, butter, cheese, cookies, including a few more oily foods.

Glassine paper formation is the result of an improved version of greaseproof paper. It has a very smooth, transparent and shiny texture. It is resistant to air and water. To separate the pieces, glassine is used as liners/ barriers between meat, fast foods, baked foods, etc.

Waxed paper prevents the entry of any type of liquid and vapour. The more the wax amount, more will be the barrier strength. It is used in the packaging of milk, milk cream, cakes, etc.

Parchment paper is formed by acid-treated pulp, which makes cellulose more impervious to oil and moisture. It is used in baking due to its heat-resistant and non-sticky nature and is therefore also known as bakery paper.

Only plain paper would not be sufficient to preserve food for a longer time period, due to its low heat sealability, less barrier property and low strength. Therefore, paper is laminated with polyethylene or aluminum to enhance its barrier properties and heat-sealability. Sometimes, paper laminates are also used to pack spices, soups and herbs.

Conclusion

The vital role that is played by food packaging is basically to maintain the wholesomeness, safety and quality of food products.

References:

• Siracusa, V. (2016). Packaging Material in the Food Industry. Antimicrobial Food Packaging, 95–106. doi:10.1016/b978-0-12-800723-5.00007-3

• Marsh, K. & Bugusu, B. (2007). Food Packaging—Roles, Materials, and Environmental Issues. Journal of Food Science, 72(3). doi:10.1111/j.1750-3841.2007.00301.x

About the Authors:

Komal Soni
M.Sc. (Nutrition Biology)
School of Interdisciplinary and Applied Sciences
Central University of Haryana, Mahendergarh, Haryana, India.
Mrinal Samtiya
Ph.D. Scholar
Department of Nutrition Biology
School of Interdisciplinary and Applied Sciences
Central University of Haryana, Mahendergarh, Haryana, India.
Email ID: mrinalsamtiya@gmail.com

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Author

An up-&-coming bloody creative professional passionately involved with both print and digital media; constantly trying to be an irritating perfectionist and surviving solely on inspiration (sometimes from the most inert objects)… Currently, staying busily engaged with producing mouth-watering content for the much anticipated and less explored Indian Food Processing Sector...

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