Preparation of nano silver based anti-bacterial coating for food packaging applications

Abstract

Food packaging plays an important role in preserving food throughout the distribution chain. Food packaging can delay food deterioration, keep the favourable properties of food processing, increase the shelf life or the usable time of the food while keeping the quality and the security of food. To maintain product quality and freshness of the food attentive selection of packaging materials and technologies should be done. The conventional food packaging used in food packaging industry are glass, metals like aluminium and tin, paper and plastics. Plastics used for food packaging can be found in wide variety with the forms of rigid or flexible. Due to design flexibility of plastics they can be formed into various structural shapes. The main two important properties of plastics are heat seal-ability and printability which can be integrated in line with the process of filling food. Variable permeability to light, gas and vapour and lack of anti-bacterial activity of the packaging applications are main drawbacks of plastics. Nowadays Nano sized particles which are in between 1-100 nm in diameter become an area of intense scientific attract due to its wide range of applications in packaging, medical, optical and electronic industries. Nano particles of metals like silver and gold disclose significantly distinct properties compared to bulk properties. The objective of this research was to prepare nano silver based anti-bacterial coating for polypropylene based food packaging applications. In this research, Ag/PVA (Polyvinyl Alcohol) solution was prepared by in situ reduction method, in which silver nitrate and polyvinyl alcohol (PVA) acted as a precursor and a capping agent. AgNPs formation was tested with UV Spectrometer. Ag/PVA was cross-linked with citric acid and coated on UV treated polypropylene sheets to make a film. Prepared samples were tested for anti-bacterial activities. Nano silver coated polypropylene samples showed enhanced anti-bacterial effect. Therefore, this technique can be developed to apply in various food packaging applications to extend the shelf life.