Researchers at the Indian Institute of Technology (IIT) in Hyderabad have succeeded in keeping tomatoes fresh for 30 days using special food packaging material. A team of two members led by Dr Mudrika Khandelwal developed the food packaging material, which is made from bacterial cellulose impregnated with silver nano particles.

The bacterial cellulose is prepared using Gluconacetobacter xylinus bacteria in order to produce semi-crystalline cellulose nano fibres from a standard substance that contained glucose. “We can use every type of fruit juice that is rich in sugar to produce bacterial cellulose”, explains Dr Khandelwal.

Smaller is better

The nano-sized pores in the bacterial cellulosic matrix restrict the growth of nanoparticles, thus controlling their growth. Dr Khandelwal: “We discovered that if the silver nanoparticles are smaller the antimicrobial activity will be greater.”


To measure the exact antibacterial activity of the bacterial cellulose the material was first tested on isolated bacteria and fungi that occur on rotting tomatoes. The test showed that the bacterial cellulose killed 99% of the bacteria up to 72 hours after the test was initiated. What’s even more remarkable in this experiment is that the food packaging material also demonstrated fungus-combating activity.

Retarding the aging process

Another test revealed that tomatoes wrapped in the bacterial cellulose packaging material remained fresh for up to 30 days when stored at room temperature. Even after 30 days, the tomatoes demonstrated neither wrinkles nor microbial spoilage. Researcher Shivakalyani Adepu indicated that this is because, in addition to the antimicrobial activity, the composite also facilitates a favourable exchange of gases and moisture. “The material ensures that the fruit ages more slowly.”

Other applications

The research team aims to test the food packaging material on exotic fruit to see if the material will also keep this fruit for a longer period of time. Dr Khandelwal says that she would also like to test the same principle on medical products. “The composite can be used as an antimicrobial lining in sanitary napkins and disposable clothing and covering in hospitals.”

Source: The Hindu.