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New anti-bacterial packaging doubles shelf-life of perishable food, packaging with Zinc reduces bacteria by 97%

New anti-bacterial packaging doubles shelf-life of perishable food, packaging with Zinc reduces bacteria by 97%

29-Jul-16

A new food wrap made from crustacean shells and fortified with grapefruit seed extract doubles the shelf life of perishable food, say researchers. Thian Eng San, an associate professor at the National University of Singapore, and PhD student Tan Yi Min developed the material with food safety and environmental sustainability in mind.
Covering leftovers with plastic wrap/cling film is a good way of keeping food fresher for longer. However, they mainly prevent spoilage by sealing everything off from oxygen, hence have fairly limited scope. Now a new kind of natural packaging wrap derived from the shells of shrimp and other crustaceans could go significantly beyond the preservation potential of today's plastic wrap. The researchers from National University of Singapore have spent three years developing their new composite material, which they say can double the shelf-life of perishable food such as bread.
The film's main constituent is chitosan, a polymer synthesised from the exoskeletons of crustaceans. According to the team, chitosan is an ideal material for use in food technology applications, as it is bio-degradable and possesses an excellent film-forming ability and is also non-toxic. Chitosan also has antimicrobial and antifungal properties, and the researchers have fortified the polymer with grapefruit seed extract (GFSE), which is antioxidant and possesses antiseptic, anti-bacterial and fungicidal properties. The resulting composite is comparable in strength and flexibility to regular food wrapping, but its molecular makeup means it can also prevent the growth of fungi and bacteria in foods it is used to cover. "Increasing attention has been placed on the development of food packaging material with antimicrobial and antifungal properties, in order to improve food safety, extend shelf-life and to minimise the use of chemical preservatives," said mechanical engineer Thian Eng San. "Consumers are also demanding that packaging materials be formulated from natural materials that are environmentally friendly and biodegradable while improving food preservation."
The findings of the team and their claims have not yet been peer-reviewed or published, but the team says in their initial testing, the shelf-life of bread samples packaged with the chitosan-based GFSE composite films was twice as long as those wrapped in synthetic packaging films. When the chitosan-based wrap without grapefruit seed extract was used on bread, fungi appeared after five days instead of three. Fungal growth was further delayed to 10 days if GFSE was incorporated into the chitosan film, the scientists discovered. The next-generation wrap also blocks out ultraviolet light, which degrades food due to oxidation and photochemical deterioration reactions. The researchers added a food-grade plasticizer to the chitosan-based wrap to make it less brittle. The fabrication process, which takes less than a day, involves mixing a solution of powdered chitosan and GFSE, filtering it, and then syringing a thin layer onto a petri dish. After drying in an oven, the solution turns into a transparent film. Larger sample sizes may take longer to produce, Yi Min adds. Presently, the researchers estimate that the film costs about 30% more than normal food wrap to produce, but they anticipate that a commercialized product will be priced similarly to its plastic counterparts. The biodegradable wrap is about three to five years away from being sold on supermarket shelves. "Extending the shelf-life of food products also means reducing food waste, and as a result, reducing the rate of global food loss," said one of the researchers, Tan Yi Min. "This will bring about both environmental and economic benefits."

The most basic and essential purpose of food packaging, especially when used for items like raw meat, fish and dairy products, is to protect the packaged food from any type of contamination that will alter its microbial and physiochemical qualities. A Dutch start up has created a material that can reduce the amount of harmful bacteria growing inside food packaging by 97%. Environmental conditions favorable to bacterial growth, such as sufficient nutrition, high humidity and suitable ambient temperature, are found on package trays. This eases the spread of dangerous bacteria like Salmonella, Listeria, E.Coli and Staphylococcus Aureus. Until now, packaging companies fought these microbes with silver or nano-silver. Nano-particles are particularly hazardous, as they can easily become loose and be inhaled or digested by humans. Moreover, these materials are usually only used as a coating, whose function degrades over time. Parx Plastics has come up with a solution to create an antibacterial tray for meats, poultry and fish, that does not contain any harmful elements. On the contrary, it uses the natural trace mineral Zinc, which is essential for the proper functioning of the human body. The company's invention - an antibacterial polymer, called Sanipolymers - securely incorporates Zinc within the material itself, which means that it cannot exit the material or wear out. Zinc prevents the cells of bacteria from multiplying, which eventually leads to cellular death. This is why the packaging was found to have 93-97% less bacteria on its surface after 24 hours, compared to conventional packaging.

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